JP3083686B2 - Supercharging pressure control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to supercharging pressure control in an internal combustion engine having a supercharger.

[0002]

2. Description of the Related Art An example of controlling the supercharging pressure of a supercharger by switching the control mode between feedback control and open control has already been proposed.

In the feedback control, a target supercharging pressure is set when the internal combustion engine is in a predetermined operating state, and the actual supercharging pressure is controlled so as to approach the target supercharging pressure. The supercharging pressure is controlled at times other than the above.

There is an example in which hysteresis is provided at the boundary of such control mode switching (Japanese Patent Laid-Open No. 4-175422). For example, a threshold value is provided at a value lower than a target supercharging pressure by a predetermined pressure, and actual supercharging is performed. When the pressure falls below this threshold, the feedback is stopped and the control is switched to the open control.

[0005]

The target supercharging pressure is successively set depending on the operation state. However, the switching of the control mode may be repeated in a short time due to the processing timing and the response delay of the change of the actual supercharging pressure.

That is, if the target boost pressure is changed to a high load side while the response of the boost pressure change is delayed while the feedback control is being performed, the threshold value also increases at the same time, and the boost pressure increases the threshold value. In this case, the feedback control is stopped and the open control is switched.However, if the boost pressure change immediately thereafter is upward, the control mode switching hunting is caused by, for example, entering the feedback control again. become.

Further, even when the target supercharging pressure temporarily rises for some reason during operation at a stable supercharging pressure during the feedback control, hunting of the control mode switching easily occurs.

In particular, when the control mode switching process is fast and the range of the upper and lower thresholds (hysteresis) is narrow, hunting of the control mode switching is likely to occur. However, it is desirable that the control mode be switched promptly during the transition of the acceleration / deceleration state.

[0009] The present invention has been made in view of such a point,
The purpose thereof is to provide a supercharging pressure control device capable of preventing hunting of the switching of the control mode and promptly switching at the time of transition.

[0010]

In order to achieve the above object, the present invention sets a target supercharging pressure when the internal combustion engine is in a predetermined operating state, and reduces the actual supercharging pressure to the target supercharging pressure. The supercharging pressure is detected by a supercharging pressure control device that switches between two types of control modes: feedback control for controlling the pressure to approach the pressure, and open control for controlling the supercharging pressure when the internal combustion engine is not in the predetermined operating state. Pressure detection means, a throttle opening change detection means for detecting a change in the opening of the throttle valve, and whether or not the internal combustion engine is in a transient state based on the throttle opening change detected by the throttle opening change detection means. Transient state determining means for determining whether or not, a switching threshold value setting means for setting a control mode switching threshold value in accordance with a target supercharging pressure, and an actual supercharging pressure detected by the supercharging pressure detecting means. Switching determining means for comparing the control mode switching thresholds set by the switching threshold setting means to determine switching of the control mode, and performing control mode switching when a switching signal from the switching determining means continues for a predetermined time. A supercharging pressure control device for an internal combustion engine, comprising: switching executing means; and limiting means for limiting a predetermined time in the switching executing means when the transient state determining means determines that the internal combustion engine is in a transient state. And

In steady operation, even if the actual boost pressure crosses the control mode switching threshold, the control mode switching is not executed unless the switching signal continues for a predetermined time. Switching hunting can be prevented.

In a transient state, the limiting means limits the predetermined time in the switching executing means, so that the control mode can be switched as soon as the actual supercharging pressure crosses the control mode switching threshold, and the response is accelerated. Sometimes they can respond immediately.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention shown in FIGS. 1 to 5 will be described below. FIG. 1 is a control configuration diagram of an intake system of an internal combustion engine according to the present embodiment.

An intake passage 1 and an exhaust passage 2 are connected to the engine main body E. The intake passage 1 is provided with a mechanical supercharger SC, an intercooler IC, and a throttle valve in order from an air cleaner A at an upstream end thereof to a downstream side. 4 are interposed. A bypass passage 3 bypassing the mechanical supercharger SC and the intercooler IC is connected to the intake passage 1, and a bypass valve 5 is provided in the bypass passage 3.

A control chamber 6 for changing the internal compression ratio is integrally provided with the mechanical supercharger SC.
Extends and is connected to the electromagnetic switching valve 8. On the other hand, a conduit 9 branches from a junction of the intercooler IC with the bypass passage 3 and is connected to the electromagnetic switching valve 8.

The electromagnetic switching valve 8 is connected not only to the conduit 9 but also to a passage 11 communicating with the atmosphere via an air cleaner 10.
The state in which atmospheric pressure is introduced from the air cleaner 10 through the passage 11 to the conduit 7 communicating with the control chamber 6 of the mechanical supercharger SC and the state in which the supercharging pressure in the intake passage 1 is introduced through the conduit 9 are switched. be able to.

When atmospheric air is introduced into the control chamber 6, the mechanical supercharger SC has a low compression ratio, and when supercharging pressure is introduced, the mechanical supercharger SC has a high compression ratio. Switching operation of the electromagnetic switching valve 8 and bypass valve driving means for opening and closing the bypass valve 5
The operation of 12 is controlled by control means C including a microcomputer.

The control means C receives detection signals from various sensors for judging the operating state of the engine.

[0019] First, the engine body E sends a detection signal to the detection to the control means C to the engine rotational speed N _E is provided the engine speed sensor 20 along the crankshaft 13, a throttle opening provided in the throttle valve 4 A detection signal of the throttle opening θ _TH is sent from the degree sensor 21 to the control means C, and a detection signal of the bypass opening θ _BP is sent to the control means C from the bypass opening sensor 22 provided in the bypass valve 5. Can be Also on the downstream side of the throttle valve 4 an intake passage 1 is sent to the control unit C detects the supercharging pressure P _B is provided with the supercharging pressure sensor 19.

The control means C controls the engine speed N _E , the throttle opening θ _TH , the supercharging pressure P _B and the bypass opening θ _BP.
Is input and processed, and the supercharging pressure control is performed by operating the electromagnetic switching valve 8 and the bypass valve driving means 12.

FIG. 2 is a flow chart for explaining a control mode for determining whether the supercharging pressure control is performed by feedback control or open control.

First, in step 1, the present target supercharging pressure P _OBJn set from the operating state is _changed to the previous target supercharging pressure P _OBJn.
It is determined whether or not it is equal to _OBJn-1, and if not, the process proceeds to step 2 where the previous value P _{OBJn-1 of} the target supercharging pressure is compared with the current value P _OBJn to compare the target supercharging pressure _POB. Determine whether _OBJ has risen or fallen, and when it rises, timer
Set tmPBL (step 4) and proceed to step 7,
On the other hand, when the timer is lowered, the timer tmPBL is set to 0 and the timer is not set (step 3), and the process proceeds to step 6.

Here, the setting of the timer tmPBL in step 4 is based on the present value θ _THn of the throttle opening as shown in FIG.
And the previous value θ _THn−1 , that is, the fluctuation range of the throttle opening, and the larger the fluctuation range of the throttle opening, the shorter the time counted by the timer tmPBL.

If there is no change in the target supercharging pressure in step 1 (P _OBJn = P _OBJn-1 ), the routine proceeds to step 5, where it is determined whether the timer tmPBL is 0 or 0.
If not 0, the process proceeds to step 7 jump over step 6, by subtracting the predetermined value D _P from the target supercharging pressure P _OBJ proceeds to step 6 when the 0, the lower threshold P _OBJl charging pressure for switching the control mode Is calculated, and the routine proceeds to step 7.

That is, in steps 1 to 6 above, when the target supercharging pressure P _OBJ decreases as shown in FIG. 4, the timer tmPBL is not set (step 3), and the lower limit threshold P _OBJL is set to the target supercharging. When the target boost pressure P _OBJ increases immediately following the pressure P _OBJ and decreases to a value obtained by subtracting the predetermined value D _P (step 6), a timer tmPBL is sequentially set (step 4). Target boost pressure P
_{When OBJ} is rising, the lower limit threshold value P _OBJL is maintained at the previous value without passing through step 6, and the target supercharging pressure P _OBJ becomes constant and the timer tm is set.
Lower threshold P value obtained by subtracting the predetermined value D _P first time Step 6 from the street target boost pressure P _OBJ when PBL becomes 0
_OBJL .

Therefore, even if the target boost pressure P _OBJ temporarily rises for some reason during the feedback control and the actual boost pressure P _B is in a constant and stable operation state, the lower limit threshold value P _OBJL is immediately set. Since the control does not follow up, the control is not switched to the open control, and the hunting of the control mode switching due to the target boost pressure returning to the original state can be prevented.

[0027] Also, when the variation of the throttle opening is large supercharging pressure P _B increases due the timer tmPBL set time shorter immediately lower threshold when raised stops by P
_The responsiveness is improved by making the _OBJL follow the target boost pressure P _OBJ .

If the lower limit threshold P _OBJL is controlled so as not to follow while the target boost pressure P _OBJ is increasing,
As shown in FIG. 6, after the target boost pressure P _OBJ increases, the lower limit threshold value P _OBJL may be controlled so as to gradually approach and follow the target boost pressure P _OBJ .

[0029] Thus Proceeding been determined lower threshold P _OBJl in step 7, selects the throttle opening threshold value TH _BPFB changing the control mode performs a table search from the target supercharging pressure P _OBJ and the engine speed N _E.

Then, in the next step 8, the throttle opening θ _THn actually detected by the throttle opening sensor 21 is compared with the throttle opening threshold TH _BPFB, and _if it is larger than the threshold TH _BPFB , the process proceeds to step 9; In step 19, the feedback flag _{FFB is set} to "0" to start the open control.

As long as the throttle opening θ _THn is smaller than the throttle opening threshold TH _BPFB, open control is always performed. Thus, the throttle opening threshold TH for switching the control mode is set.
Since _BPFB is selected based on the target supercharging pressure P _OBJ, the throttle opening threshold value TH with the increase of the target supercharging pressure P _OBJ
By appropriately setting the _BPFB , it is possible to quickly switch to the open control at the time of deceleration or the like, improve the response, and improve the drivability.

When the throttle opening θ _THn is larger than the throttle opening threshold TH _BPFB and proceeds to step 9, the absolute value of the difference between the current value θ _THn and the previous value θ _THn-1 of the throttle opening, that is, the throttle opening The variation range of θ _TH is the predetermined value D _TH
It is determined whether the value is larger or smaller. If the value is larger, it is determined that the acceleration or deceleration is in transition.

When the fluctuation width of the throttle opening θ _TH is small and the engine is in a steady operation, the process proceeds to step 11, and the throttle opening θ _TH
If the range of fluctuation is large, go to step 10 and set the timer
tmS is set to 0 and the routine proceeds to step 11. In step 11, it is determined from the feedback flag _FFB whether or not the feedback control is being performed. If the feedback control is being performed, the process jumps to step 16, and if the open control is being performed, the process proceeds to step 12.

During open control (F _FB = 0), step
If the process proceeds to 12, the supercharging pressure P _B as compared to the target supercharging pressure P _OBJ, and sets a timer tmSCFB jumps to step 18 when not reached the target supercharging pressure P _OBJ, the next step
The feedback off Love F _FB 19 to continue the open control as "0".

The boost pressure in the step 12 P _B is the target supercharging pressure P
_{If OBJ} is exceeded, proceed to step 13 to set timer tmSC
It is determined whether or not FB has become 0, and until the value becomes 0, the process jumps to step 19 to maintain the feedback flag F _FB at “0” and continues the open control. When the timer tmSCFB becomes 0, the process proceeds to step 14. Go ahead and set the timer tmSCFB,
In the next step 15, the feedback flag _FFB is set to "1" to switch to feedback control.

As described above, in the state where it is determined in step 9 that the engine is in the normal operation and the timer tmSCFB is not forcibly set to 0, the supercharging pressure P _B is set to the target supercharging pressure P _OBJ during the open control.
Is not exceeded, the feedback flag F _FB = 0 through the routes of steps 11, 12, 18, and 19.
Step supercharging pressure P _B to the set timer tmSCFB in step 18 exceeds the target supercharging pressure P _OBJ becomes 0 1
Open control is continued through 2, 13, and 19, and the timer t
Only when mSCFB becomes 0, steps 12, 13, 14, 15
The make a "1" as the feedback flag F _FB is switched to the feedback control, subsequent step 11, 16,
Through the steps 14 and 15, the feedback flag F _FB = 1 is maintained.

Therefore, the target boost pressure P, which is the upper threshold,
Even beyond the _OBJ supercharging pressure P _B predetermined timer time can be prevented switching control hunting mode it does not switched to the feedback control.

On the other hand, during feedback control (F _FB = 1)
Then, when proceeding from step 11 to step 16,
When the lower threshold P _OBJl greater than the supercharging pressure P _B determined in Step 1 to Step 6 sets the timer tmSCFB jumps to step 14, F _FB = 1 in the next step 15
And the feedback control is continued.

The boost pressure in the step 16 P _B is the target supercharging pressure P
_{If the value} is lower than _OBJ , the process proceeds to step 17 and the timer tmSCFB is set to 0.
Determines whether it is, until the 0 continued to feedback control as F _FB = 1 jumps to step 15, the timer tmSCFB becomes 0, the timer proceeds to step 18
Set the TmSCFB, it switched to the open control feedback flag F _FB in the next step 19 as "0".

That is, when the supercharging pressure P _B does not fall below the lower limit threshold value P _OBJL during steady-state operation by feedback control, the feedback flag F _FB = 1 through the routes of steps 11, 16, 14, and 15. but the boost pressure P _B is the feedback control through steps 16,17,15 until the timer tmSCFB set in step 14 is below the lower threshold P _OBJl becomes 0 is continued, and the timer tmSCFB becomes zero first step 16, 17, 18 and 19 as the feedback flag F _FB "0" is switched to the open control enters, thereafter is being maintained feedback flag F _FB = 0 through the steps 11,12,18,19 .

[0041] Thus since the supercharging pressure P _B is not switched to the open control is a predetermined timer time even below the lower threshold P _OBJl, it is possible to prevent switching control hunting mode by a response delay, etc. of the supercharging pressure P _B .

As described above, during the normal operation, the timer tmSCFB
Works to prevent control mode switching hunting, but during transition, the timer tmSCFB is set to 0 by going from step 9 to step 10 and the timer tmSCFB does not operate. When the boost pressure P _B exceeds the target boost pressure P _OBJ during control,
Also, during the feedback control, the supercharging pressure P _B is set to the lower threshold P
_{When the value} falls below _OBJL , the control mode is immediately switched, so that responsiveness can be improved and drivability can be improved.

In this embodiment, in the setting of the timer tmSCFB in the step 14 or the step 18, as shown in FIG. 5, depending on the fluctuation range θ _THn −θ _THn-1 of the throttle opening, whether the vehicle is accelerating or decelerating. The time measured by the timer tmSCFB is determined accordingly.

That is, when the fluctuation of the throttle opening is large, the set time of the timer tmSCFB is shortened to improve the response of the control mode switching. In addition, the set time of the timer tmSCFB is set shorter during deceleration than during acceleration, so that the shift to open control is particularly accelerated so that a sense of deceleration can be obtained.

[0045]

According to the present invention, the control mode is not switched if the switching signal does not continue for a predetermined time even if the actual boost pressure crosses the control mode switching threshold during the steady operation. Control mode switching hunting due to a response delay or the like can be prevented.

In the transient state, the control means limits the predetermined time in the switching executing means, so that the control mode can be switched as soon as the actual supercharging pressure crosses the control mode switching threshold value, and the response is accelerated. And drivability can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an intake control system of an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control procedure according to the embodiment.

FIG. 3 shows a timer tmPBL according to a change in throttle opening.
It is a figure which shows the setting time of.

FIG. 4 is a diagram showing changes in a target supercharging pressure and a lower threshold.

FIG. 5 shows a timer tmSC according to a fluctuation range of the throttle opening.
FIG. 6 is a diagram illustrating a set time of an FB.

FIG. 6 is a diagram showing changes in a target supercharging pressure and a lower limit threshold according to another embodiment.

[Explanation of symbols]

E: engine body, A: air cleaner, SC: mechanical supercharger,
IC: ink cooler, C: control means, 1: intake passage, 2
... Exhaust passage, 3 ... Bypass passage, 4 ... Throttle valve, 5
... bypass valve, 6 ... control room, 7 ... conduit, 8 ... electromagnetic switching valve, 9 ... conduit, 10 ... air cleaner, 11 ... passage, 12 ... bypass valve driving means, 13 ... crankshaft, 19 ... intake pressure sensor, 20 ... engine speed sensor, 21 ... throttle opening sensor, 22 ... bypass opening sensor.

Claims (1)

(57) [Claims] 1. A feedback control for setting a target supercharging pressure when the internal combustion engine is in a predetermined operating state and controlling the actual supercharging pressure to approach the target supercharging pressure; A boost pressure detecting device for detecting a boost pressure, and a throttle for detecting a change in the opening of a throttle valve. Opening degree change detecting means; transient state judging means for judging whether or not the internal combustion engine is in a transient state based on the throttle opening degree change detected by the throttle opening degree detecting means; and control according to the target boost pressure. Switching threshold setting means for setting a mode switching threshold, and comparing the actual supercharging pressure detected by the supercharging pressure detecting means with the control mode switching threshold set by the switching threshold setting means. Switching determining means for determining switching of the control mode; switching performing means for performing switching of the control mode when a switching signal from the switching determining means has continued for a predetermined time; and a transient state determining means for determining whether the internal combustion engine is in a transient state. And a restriction means for restricting a predetermined time in the switching execution means when it is determined that the supercharging pressure is within the range.