JPH02201029A - Supercharge pressure control device for engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent the overshoot and the undershoot of the supercharger pressure at the moving time of the operated condition of an engine by setting the guard value of the feedback value relatively small when the engine load is small. CONSTITUTION:When the supercharge pressure is controlled, that is when the operation duty of a duty solenoid valve provided in a pressure passage through which the supercharge pressure is taken out is decided, first, the base duty, the target supercharge pressure and the real supercharge pressure are respectively computed in each computing unit 30-32. Next, a computing unit 33 computes the feedback duty on the basis of each output from each computing unit 31, 32. Continuously, a judging unit 34 judges whether it is the acceleration or not, while respectively correcting to accelerate the base duty and the feedback duty at the acceleration time. And the computing unit 35 computes the output duty based on outputs of each computing unit 30, 33. At this stage, when the engine load is small, the guard value of the feedback value is set small.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a boost pressure control device for a supercharged engine.

(Prior art) As such a boost pressure control device, for example, Japanese Patent Application Laid-open No. 6
As disclosed in Japanese Patent No. 1-16240, an overcharging system for a supercharged engine equipped with a feedback means for feedback controlling the supercharging pressure to a target supercharging pressure set in advance according to the operating state of the engine, etc. Supply pressure control devices are known.

In such a boost pressure control device, when the engine load is low, the output of the engine is usually small, so there is a tendency to increase the target boost pressure, and therefore the amount of feedback also tends to increase.

(Problem to be solved by the invention) In the above state, for example, engine load,
When transitioning from low load to high load, at the beginning of the transition, a large amount of feedback as mentioned above at low load is reflected, resulting in the problem of overshoot of boost pressure. . On the other hand, when the engine load shifts from low load to high load, undershoot tends to occur.

Therefore, it is an object of the present invention to provide a supercharging pressure control device for a supercharged engine that can prevent overshoot and undershoot of the supercharging pressure when the operating conditions of the engine change as described above. This is the purpose.

(Means for Solving the Problems) The present invention has been made by focusing on the fact that in feedback control, guards are provided as upper and lower limits of the feedback value, and the boost pressure is set in advance. In a boost pressure control device for a supercharged engine, the boost pressure control device for a supercharged engine is provided with a feedback means for performing feedback control on a target boost pressure set by a target boost pressure, and a guard value of a feedback value of the feedback means is set such that a guard value of a feedback value of the feedback means is set when the engine load is small and when the engine load is large. In contrast, it is characterized by being set relatively small.

(Operations and Effects of the Invention) In the supercharging pressure control device for a supercharged engine of the present invention, as described above, the guard value of the feedback value of the feedback means is set when the engine load is small and when the engine load is large. Since the feedback value is set to be relatively small, when the engine load is small, the feedback value will also be below the predetermined small value.
When the target boost pressure shifts to a different operating state book, it is possible to prevent overshoot or undershoot of the boost pressure due to the feedback value before the shift being reflected. Note that when the engine load is large, the guard value is left as is, so a sufficient feedback value can be obtained and good feedback control can be performed.

(Embodiments) Hereinafter, a supercharging pressure control device for a supercharged engine according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a supercharging pressure control device for a supercharged engine according to an embodiment of the present invention. In this figure, reference numeral 1 indicates a blower 3 interposed in an intake passage 2, 4
This figure shows a rotary piston engine that is a supercharged engine that pressurizes and supplies intake air by a turbine 5 installed in the engine. A mechanical gamma cleaner 6 and an air flow meter 7 are installed on the upstream side of the blower 3 in the intake passage 2, and an intercooler 8 and a throttle valve 9 are installed on the downstream side.
, and primary and secondary fuel injectors 10.1
1 is provided. This fuel injection valve 1O111 is communicated with a fuel tank 12 via a fuel passage 13,
The fuel in the fuel tank 12 is supplied by the fuel pump 14. In addition, the fuel injection valve 10.1
1 is connected to a control unit 15 consisting of a microcomputer, and this control unit 15 receives the output signal from the air flow meter 7 and calculates the fuel supply amount according to the intake air amount based on this signal. It also controls the opening time of the fuel injection valves 10.11. The fuel passage 13 is provided with a pulsation prevention damper 16 for preventing pulsation in the fuel supply, and a pressure regulator 17 for adjusting the pressure of the fuel to a predetermined pressure.

The exhaust passage 4 has a bypass passage that bypasses the turbine 5 and relieves the exhaust pressure upstream of the turbine 5 downstream of the turbine! 20 are provided.

This bypass passage 20 is provided with a waste gate valve 21 for adjusting the passage area of this bypass passage 20, controlling the amount of exhaust gas flowing through the bypass passage, and controlling the supercharging pressure.

This waste gate valve 21 is of a normal diaphragm type structure, and although not shown in the drawings, its pressure chamber contains a pressure for taking out the intake pressure downstream of the turbine 3 having an intake air amount ia2, that is, the supercharging pressure. A passage 22 is in communication.

A pressure relief passage 23 is communicated with this pressure passage v&22 at one end thereof, and the pressure relief passage 23
The other end is the air flow meter 7 of the intake passage 2 and the blower 3.
It is connected to the part between. In this pressure passage 22,
A duty solenoid valve 24 is provided to open and close a portion in the middle. The duty solenoid valve 24 has its operation duty ratio controlled by the control unit 15, and relieves the boost pressure from the pressure passage 22 according to the duty ratio.
Thereby, the pressure acting on the pressure chamber of the diaphragm type waste gate valve 21 is controlled, the opening degree of this waste gate valve 21 is adjusted, and as described above,
It is designed to adjust the boost pressure.

The control unit 15 includes a throttle opening sensor 25, an atmospheric pressure sensor 26, and an engine rotation speed sensor 2.
7. Sensors for detecting the operating state of the engine, such as a vehicle mileage sensor 28 and a boost pressure sensor 29, are connected.

The control unit l-15 is configured to:
While calculating the target boost pressure, the actual boost pressure is detected by the boost pressure sensor 29, and feedback control is performed so that the actual boost pressure becomes the target boost pressure.

Next, the control of supercharging pressure by the control unit 15 will be explained with reference to FIG. 2 and subsequent figures.

FIG. 2 shows the control of the boost pressure by the control unit 15, that is, the duty solenoid valve 24.
FIG. 2 is a block diagram for explaining an outline of control for determining the operating duty of the controller.

In this figure, reference numeral 30 denotes a pace duty calculating section for calculating the basic pace duty FB from the engine speed and throttle opening, and numeral 3I similarly calculates the basic pace duty FB from the engine speed and throttle opening. , a target boost pressure calculation section that calculates the target boost pressure PO, and a reference numeral 32 that calculates the actual boost pressure by averaging the output signals from the boost pressure sensor 29. Department.

The target boost pressure calculation unit 31 and the actual boost pressure calculation unit 32 receive output signals from these calculation units 31 and 32,
Feedback duty PF based on these signals
Feedback duty calculation unit 3 for calculating B
3 is connected.

The feedback duty calculation unit 33 stores in advance a guard map showing the maximum and minimum values of the feedback duty as shown in FIG. This guard map includes a first maximum guard ll and a first minimum guard I12 that are used when the engine load, that is, the throttle opening is below a predetermined value, and a second maximum guard that is used when the engine load, that is, the throttle opening is above a predetermined value. It has a guard 13 and a second minimum guard 14. 1st Max Guard 11
The values of the second maximum guard 13 and the second minimum guard f2 are set, for example, to +10% and -10% as the duty ratio, respectively.
For example, the value of 4 is +30%, -3 as a duty ratio.
Each is set to 0%. That is, the values of the first max guard 11 and the first minimum guard 12 are set smaller than the values of the second max guard 13 and the second minimum guard 14. In this feedback duty calculating section 33, the calculated feedback duty value is compared with the guard according to the throttle opening degree, and if it is within that value, the calculated feedback duty is used as is, and if it is more than that, the calculated feedback duty value is used as is, and if it is more than that, the calculated feedback duty value is used as is. The value is used to limit the feedback duty so that it does not exceed a predetermined value.

An acceleration determination unit 34 is connected to the pace duty calculation unit 30 and the feedback duty calculation unit 33, and the acceleration determination unit 34 determines whether or not acceleration is occurring. This causes the duty to perform acceleration correction.

The pace duty calculation section 30 and the feedback duty calculation section 33 include an output duty calculation section 35.
is connected, and the output duty FD, that is, the operation duty of the duty solenoid valve 24 is calculated by adding the pace duty PB calculated by the calculation units 30 and 33 and the feedback duty PFB, and the control is performed. finish.

Next, details of the control for each block in the control explained above will be explained with reference to FIG. 4 and subsequent figures.

Pace-knee In the calculation section 30, first, in step S1, it is determined whether the fuel being used is regular based on the regularity determination flag REG. This judgment is YES
, that is, when the fuel is regular, in step S2, the pace duty FB2 is calculated based on the quadratic interpolation map (regular pace duty map) MBPBREG with the engine speed NE and throttle opening TVO as parameters. On the other hand, when the above judgment is NO, that is, when the fuel is high-octane, in step S3, a quadratic interpolation map (
High-octane pace duty map) MBPB) (10
Pace duty PB2 is calculated based on.

Next, in step S4, the regularity determination flag R
EG is off, flag MLG2 indicating that the mileage of the vehicle is greater than or equal to a predetermined value is off, that is, flag PI indicating that the mileage is less than or equal to a predetermined value and the intake manifold pressure is greater than or equal to a predetermined value. Determine whether it is on. When this determination is YES, in step S5, the primary ? i
! Interval table (constant/rotary table for mileage correction) T
A mileage correction coefficient PBMLG is calculated based on BPBMLG. On the other hand, when the above determination is NO, step S
In step 6, the mileage correction coefficient PBMLG is set to O. Note that in step S5 above, the mileage correction coefficient PBMLG
The table used for the calculation can be, for example, as shown in FIG.

Next, in step S7, the atmospheric pressure correction coefficient P is calculated based on the linear interpolation table (atmospheric pressure correction constant/atmospheric pressure table) TBPBA which uses the atmospheric pressure ATP as a parameter.
Calculate BATP. Note that in this step S7, for example, a table as shown in FIG. 6 can be used. Thereafter, in step S8, the throttle opening degree TVOAH for acceleration determination is calculated based on the linear interpolation table (constant/rotation table of throttle opening degree for acceleration determination) TBTVOAH, which uses the engine rotation speed NE as a parameter. Note that in this step S8, for example, a table as shown in FIG. 7 can be used.

Next, in step S9, the actual throttle opening TVO
The current acceleration state is determined by determining whether A is larger than the acceleration determination throttle opening TVOAH or whether the acceleration determination flag PCTVOA is on. This judgment is YES
In this case, in step S10, it is determined whether the actual boost pressure PN is smaller than the value obtained by subtracting a predetermined constant KBPK from the target boost pressure PO, and when this determination is YES, in step 311, acceleration correction is performed. A predetermined constant KBPBC is set as an acceleration correction coefficient PBC, and on the other hand, when this determination is NO,
In step $12, in order to perform attenuation processing, the acceleration correction coefficient PBC is determined by subtracting the constant KBPBCDEC from the previous acceleration correction coefficient PBC(i-1). Step S above
If the judgment in step 9 is NO, the vehicle is not accelerating, so
In step S13, the acceleration correction coefficient PBC is set to 0. Finally, the pace duty PB is calculated using the formula shown in step 314, and the control is ended.

In the calculation unit 31, first, in step S21, it is determined whether the fuel being used is regular based on the regularity determination flag REG. This judgment is YES
When S, that is, when the fuel is regular, in step 322, a quadratic interpolation map (regular base target boost pressure map) MBPOREG is created using the engine speed NE and throttle opening TVO as parameters.
On the other hand, when the above determination is No, that is, when the fuel is high-octane, in step S23, a quadratic interpolation map is calculated based on the engine speed NE and throttle opening TVO. (High-octane base target boost pressure map) MBOBH
Base target boost pressure POB is calculated based on I○. These calculations of the base target boost pressure POB can be performed using, for example, a base target boost pressure map as shown in FIG.

Next, in step 324, the regularity determination flag REG is off, and the flag MLG2 indicating that the mileage of the vehicle is greater than or equal to a predetermined value is off, that is, the mileage is less than or equal to a predetermined value, and the intake manifold pressure is a predetermined value. It is determined whether the flag Pi indicating the above is on. If this determination is YES, step S25
, a linear interpolation table (constant/rotation table for mileage correction) T with the engine speed NE as a parameter.
Based on BPOMLG, mileage correction coefficient POMLC;
On the other hand, when the above judgment is No, the above-mentioned mileage correction coefficient PBMLC is set to 0 in step S26. In addition, in step S5 above, the mileage correction coefficient PO
Examples of tables used for MLG calculations include:
It may be as shown in FIG.

Next, in step 327, the engine speed NE
A linear interpolation table (coefficient constant of Maxguard, which is the highest limit of the target boost pressure, see Figure 11) with TBPON as a parameter, is applied to the maximum value based on the atmospheric pressure ATP shown in Figure 12. By multiplying the max guard value obtained from the guard POMAX calculation map, the max calculates the value of the single guard POMAX.

Next, in step 32g, the base target boost pressure PO
The value obtained by subtracting the mileage correction body @POMLG from B is greater than (or equal to) the Max Guard POMAX above.
Determine whether When this determination is YES, the Max Guard POMAX is set to the target boost pressure PO in step S29, and when this determination is No, step S30
Then, the subtracted value is set as the target supercharging pressure PO, and the control is ended.

In this calculation section, the average value of the past three detected values and the current detected value of the intake manifold pressure P is set as the value of the actual boost pressure PN using the formula %().

In the calculation section of the food engine, first, in step 331, the actual throttle opening TVOA is smaller than the throttle opening TVOAH for acceleration determination, or the acceleration determination flag PCTVOA is off, or the actual supercharging By determining whether pressure PN is larger than (or equal to) a value obtained by subtracting a predetermined constant KBPK from target boost pressure PO, it is determined that acceleration is not being performed and whether acceleration correction value PBC is zero.

When this determination is No, the feedback duty PFB is set to 0 in step S32, and the control is terminated.On the other hand, when the above determination is YES, in step S333,
Subtract PO from actual boost pressure PN to calculate the difference ΔP.

After that, in step 334, the above difference ΔP is converted into a linear interpolation table using parameters (constant of feedback control gain/table of ΔP) TBDPFB (see FIG. 14).
Based on this, the feedback control gain DPFB is calculated. By the way, in conventional boost pressure feedback control, the control gain of the feedback means is set to a relatively small value both when the actual boost pressure is higher and lower than the target boost pressure. Even when the actual boost pressure is higher than the target boost pressure, there is a problem in that the convergence to the target boost pressure is slow and the engine is exposed to high load for a long time.

Therefore, in this embodiment, a feedback control gain characteristic map as shown in FIG. 14 is stored in advance in the control unit 15, and feedback control of the boost pressure is performed according to this control gain characteristic map. There is. In this control gain characteristic map, the horizontal axis shows the difference ΔP obtained by subtracting the target boost pressure from the actual boost pressure, and the actual boost pressure increases as you go to the right, and the vertical axis shows the control of feedback control. Gain DPFB is shown.

As can be seen from this figure, the control gain DPFB of the feedback control is set to increase as the actual boost pressure is larger than the target boost pressure and the difference ΔP between them increases. When the actual boost pressure is higher than the target boost pressure, the actual boost pressure is quickly reduced to the target boost pressure.

Next, in step S35, the actual throttle opening TV
It is determined whether OA is larger than the throttle opening degree TVOAH for acceleration determination, and when this determination is YES, step S36
, the constant KBPFBMXHSKB is a relatively large value.
Feedback duty PF for each PFBMNH
Max Guard P F BMA that determines the upper and lower limits of B
X, minimum guard PFBMIN (line 13 in Figure 3)
and 14). On the other hand, if the determination in step 334 is NO, step 33
In step 7, it is determined whether the actual boost pressure PN is larger than the target boost pressure PO. If this determination is YES, it is determined that there is an abnormality, so in step 338, the
Let X be a relatively small constant KBPFBMXL (line 11 in Figure 3), and set the minimum guard PFBMI on the down side.
N is a constant KBPFBMNH (third
Let it be line 14) in the figure. Here, the actual throttle opening T
Even when the VOA is small, that is, the engine load is small, when the actual boost pressure PN is larger than the target boost pressure PO, the minimum guard PFBMIN is set to a relatively large value (the third
By setting If 4) in the figure, it is possible to secure a wide control range for reducing the boost pressure, and to ensure the reliability of the engine.

On the other hand, when the determination in step S37 is NO, in step S39, the constant KB, which is a relatively small value, is
PFBMXL, KBPFBMNL (line 11 in Figure 3).
12) respectively Maxguard P F BMA X,
Set the minimum guard to PFBMIN.

Next, in step S40, the sum of the previous feedback duty PFB (i-1) and DPFB (calculated as the current feedback duty PFB) is smaller than the Max Guard PFBMAX (
If the determination is No, in step S41, the current feedback duty PFB
is set as the value of Max Guard P F B MA X and the control is terminated.

On the other hand, when this determination is YES, in step S42, the previous feedback duty PFB (
i-1) plus DPFB (calculated as the current feedback duty PFB) is greater than (or equal to) the above minimum guard PFBMIN
If this determination is NO, step S4
In step 3, the current feedback duty PFB is set as the value of the minimum guard PFBMIN and the control is terminated.
When this determination is YES, the sum of the previous feedback duty PFB (i-1) and DPFB (calculated as the current feedback duty PFB) is calculated as the current feedback duty PFB.
Terminate control as .

In the determination unit 34, first, in step S51, it is determined whether the acceleration determination flag PCTVOA is currently 1, that is, whether it is in the on state. This judgment is Y
At the time of ES, in step S52, it is determined whether the actual throttle opening TVOA is smaller than the throttle opening TVOAH for acceleration determination, or the actual boost pressure PN is smaller than the target boost pressure PO.
If the determination is NO, in step 353, the acceleration determination flag PCT is
The control is ended by setting VOA to 11, that is, the on state, and when this determination is YES, in step S54, the acceleration determination flag PCTVOA is set to 0, that is, the off state, and the control is ended.

Further, when the determination in step S51 is NO, whether the difference between the current actual throttle opening TVOA (i) and the previous actual throttle opening TVOA (i-1) is greater than (equal to) a predetermined constant KBTVOA. is determined, and when this determination is YES, the above step S53
At step 354, the acceleration determination flag PCTVOA is set to 1, that is, turned on, and the control is terminated.If this determination is NO, the acceleration determination flag PCTVOA is set to 1, that is, the ON state.
The control is ended by setting A to 0, that is, the off state.

In this calculation section, the feedback duty PFB is added to the base duty PB, and the output duty F
D is calculated, but if this output duty PD is 95% or more or 5% or less, it is not a desirable state, so according to the flowchart shown in Fig. 15, PB + PFB When the value of is 95% or more, this 95% is set as the output duty FD, and P
B+ P F When the value of B is 5% or less, this 5%
is the output duty FD, and only at other times, F
The value of B+PFB is set as the output duty FD.

[Brief explanation of the drawing]

FIG. 1 shows the entire supercharging pressure control device 4REti for a supercharged engine according to an embodiment of the present invention, and FIG. 2 explains the state of supercharging pressure control in the supercharging pressure control device. Figure 3 is a diagram showing a guard map of feedback values used in the boost pressure control device, Figure 4 is a flow chart diagram for explaining control in the base duty calculation section, and Figure 5 is a diagram showing the block factors for the above. 6 is a diagram showing the characteristics of mileage correction, FIG. 6 is a diagram showing the characteristics of atmospheric pressure correction, and FIG. 7 is a diagram showing the characteristics of atmospheric pressure correction.
8 is a flowchart for explaining the control in the target boost pressure calculating section. FIG. 9 is a diagram showing the target boost pressure characteristic map. , FIG. 10 is a diagram showing the characteristics of the traveling path a correction in the target boost pressure calculation section, FIG. V11 is a diagram showing the characteristics of the max guard coefficient in the target boost pressure calculation section, and FIG. FIG. 13 is a flowchart for explaining the control in the feedback duty calculation section, and FIG. 14 is a diagram showing the characteristics of Max Guard in the supply pressure calculation section.
A diagram showing a feedback control gain characteristic map used in the boost pressure control device, FIG. 15 is a flowchart diagram for explaining the control in the acceleration determination section, and FIG. 16 is a diagram for explaining the control in the output duty calculation section. It is a flowchart figure for doing. l Supercharged engine 15 Control unit 30 Base duty calculation section 31 Target boost pressure calculation section 32 Actual boost pressure calculation section 33 Feedback duty calculation section 35 Output duty calculation section Fig. 2 Fig. 3

Claims (1)

[Claims] In a supercharging pressure control device for a supercharged engine, which includes a feedback means for feedback-controlling the supercharging pressure to a preset target supercharging pressure, a guard value of the feedback value of the feedback means is set when the engine load is small. A supercharging pressure control device for a supercharged engine, characterized in that the boost pressure is set to a relatively small value when the engine load is large.