JPH076443B2 - Supercharging pressure control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a knocking control device that controls a retard amount of ignition timing according to a signal from a knock detector, and a boost pressure according to the retard amount. The present invention relates to an internal combustion engine with a supercharger, which also has a supercharging pressure control device for controlling the engine.

[Conventional technology]

In order to prevent knocking in a spark type internal combustion engine, there is a device (so-called KCS device) that controls ignition timing according to a knocking state signal from a knocking detector. In this device, if knocking is detected, the ignition timing is retarded from the base value, and as a result, if the knocking is eliminated, the ignition timing retard amount is decreased, and the ignition timing is set within a range where knocking does not occur through such feedback control. It should be kept as close to the base value as possible.

Considering the case where the KCS device and the supercharging value are combined, the intake pipe pressure and the intake air temperature rise due to the supercharging operation, so that knocking is likely to occur. Assuming that a low octane fuel is used as the fuel, the tendency of knocking to occur is promoted, and the retard amount of the ignition timing becomes significantly large. As is well known, if the retard amount of the ignition timing becomes excessively large, the exhaust gas temperature may increase and the durability of the catalytic converter may deteriorate. Moreover, retarding the ignition timing also deteriorates the fuel consumption rate.

Therefore, as a technique of the prior application, it has been proposed to detect the retard amount of the ignition timing in an internal combustion engine with a supercharger and control the supercharging pressure in magnitude according to the retard amount. For example, JP-A-60
See -289358. According to this prior art device, different reference values of the retard angle amount are set for each of a number of determination regions according to the number of revolutions, and the ignition retard amount of the ignition timing is greater than the predetermined value in a predetermined number or more of the determination regions. When it becomes large, the supercharging pressure set by the supercharger is controlled to be small. Therefore, when the retard correction amount increases due to the use of low-octane fuel, the boost pressure setting is controlled to a small value, and as a result, the retard amount is held at an appropriate value and the exhaust gas temperature is controlled to an appropriate temperature. Become.

[Problems to be solved by the invention]

In the prior application technology, the supercharging pressure is set small when the retard amount exceeds the discrimination reference value in a predetermined number or more of the discrimination regions, and the number of determination regions in which the retard amount exceeds the discrimination reference value is the predetermined value. When it is below the value, the boost pressure is set high. In this case, if there is a change in the determination result in a certain determination range, frequent transitions (hunting) occur between high and low boost pressure settings, degrading engine drivability.

An object of the present invention is to provide a supercharging pressure control device in which hunting does not occur even if there is a change in the determination result in each determination range.

[Means for solving problems]

As shown in FIG. 1, the combustion engine includes a supercharger 1a and ignition timing control means 1b that increases or decreases the ignition timing retard amount depending on whether knocking has occurred. The supercharging pressure control device of the present invention is
The supercharging pressure control means 2 for controlling the supercharging pressure obtained by the supercharger to high and low, the delay amount detecting means 1c for detecting the retard amount obtained by the ignition timing control means 1b, and the retard amount. Whether the boost pressure is high or low is set by comparing the reference value of the retard amount set in each of the judgment regions set according to the influencing engine operating condition factors and the actual retard amount. Discriminating means 3, 3 ', ...
.., and a means 4 for accumulating the discrimination results of the respective discrimination means, and a supercharging pressure actuation means 2 when the actual retard amount exceeds a reference value of the retard amount in a predetermined number or more of judgment regions. The means 5 for supplying a signal for lowering the pressure and the number of operating ranges in which the actual retard amount exceeds the reference value of the retard amount are less than a predetermined number which is at least 2 less than the above-mentioned predetermined number. It comprises a means 6 for supplying a signal for increasing the boost pressure to the boost pressure operating means 2.

[Work]

The retard amount detecting means 2 detects the retard amount of the ignition timing by the ignition timing control means 1. The discriminating means 3, 3 ', ... Determining whether or not the retard amount exceeds the determination reference value in their respective determination areas, and the accumulating means accumulates the determination results of the respective determining means.
The low supercharging pressure control means 5 sends a signal to the supercharging pressure control means 2 so that the supercharging pressure becomes low when the retard amount exceeds the reference value in a predetermined number of judgment regions or more. On the other hand, the high supercharging pressure control means 6 controls the supercharging pressure so that the supercharging pressure becomes high when the number of judgment areas in which the retard amount exceeds the judgment reference value is smaller than the predetermined number by at least two. Send a signal to the means 2.

〔Example〕

An embodiment will be described below with reference to the drawings. In FIG. 2, 10 is a cylinder block, 12 is a piston, 14 is a connecting rod, 16 is a cylinder head, 17 is a spark plug, and 18 is a spark plug.
Is an intake valve, 20 is an intake port, 22 is an exhaust valve, and 24 is an exhaust port. The intake port 20 includes a fuel injector 25, a surge tank 26, a throttle valve 27, intake pipes 28 and 30, a hose 32.
Is connected to the air flow meter 34 via. On the other hand, the exhaust port 24 is connected to the exhaust pipes 36 and 38.

A turbocharger 40 as a supercharger includes a compressor 40a and a turbine 40b. The compressor 40a is arranged between the intake pipes 28 and 30, while the turbine 40b is arranged between the exhaust pipes 36 and 38. A bypass passage 42 is connected so as to bypass the turbine 40b, and a wastegate valve 44 is arranged in the bypass passage 42. The waste gate valve 44 is connected to the diaphragm 50a of the diaphragm mechanism 50 via the crank lever 46. Spring 50b biases wastegate valve 44 through rod 48 and lever 46 to close it. The pressure chamber 50c formed on the opposite side of the spring 50b is connected via a pressure guiding pipe 52 to a supercharging pressure extraction port 53 formed in the intake pipe 28 downstream of the compressor 40b. Therefore, the boost pressure generated downstream of the compressor is
The waste gate valve 44 is actuated in the valve opening direction against the spring 50b by acting on the diaphragm 50a. The throttle 52a is installed in the conduit 52, and this is to appropriately set the amount of pressure introduced into the pressure chamber 50c.

One end of the air bleed passage 54 is connected to the conduit 52, and the other end is connected to the intake pipe 30 upstream of the compressor 40a. A bleed control valve 56 is arranged in the air bleed tube 54. When the bleed control valve 56 is opened, an amount of air corresponding to the size of the throttle 54c is introduced into the pressure chamber 50c to lower the pressure applied to the diaphragm 50a. As a result, compared with the case where the air is not bleed, the pressure in the pressure chamber 50c must be the spring in the diaphragm 50a unless the pressure in the pressure extraction port 53 becomes higher by that amount.
It cannot be displaced against 50b. In the following description, the state in which the bleed control valve 56 is open is referred to as the supercharging pressure High state for convenience, while the state in which the bleed control valve 56 is closed is referred to as the supercharging pressure Low state. The bleed air amount can be continuously controlled by the bleed control valve 56. Therefore, the supercharging pressure can be continuously controlled from a small value when the bleed control valve 56 is closed to a large value when the bleed control valve 56 is opened. Bleed control valve 56 is connected to solenoid 57
57 is connected to an amplifier 58 such as a transistor, and a solenoid
The opening degree of the bleed control valve 56 corresponding to the current applied to 57 (or the current equivalent value such as the duty ratio) can be obtained. A pulse signal is applied to the transistor 58 from a control circuit 64, which will be described later, and the opening degree of the bleed control valve 56, in other words, the boost pressure is obtained according to the ratio (duty ratio) of the ON time in one cycle of the pulse signal. To be

Reference numeral 60 denotes a distributor, the center electrode of which is connected to the ignition coil 62, and the distribution of the high voltage to the ignition plug 17 of each cylinder is performed in a known manner. The igniter 63 is driven by the ignition signal from the control circuit 64.

The control circuit 64 is for driving the igniter 63, the solenoid 57 of the bleed control valve 56, and another engine control device (not shown) that is not directly related to the present invention and is configured as a microcomputer system.
The control circuit 64 carries out the necessary calculations with the signals from the various sensors and forms the control signals. The control circuit 64 includes a micro processing unit (MPU) 64a, a memory 64b,
It consists of an input port 64c, an output port 64d, and a bus 64e connecting these elements.

The input port 64c is connected to the following sensor, and various detection signals are input. From the air flow meter 34, a signal corresponding to the intake air amount Q to the engine is input. The A / D converter 66 converts the analog signal from the air flow meter 34 into a digital signal.

Crank angle sensors 68, 69 are arranged on the distributor 60, and a pulse signal corresponding to the rotation of the distributor's distribution shaft 60a is obtained. The first crank angle sensor 68 generates a pulse signal G for each rotation of the distributor shaft 60a, that is, every 720 ° CA, which serves as a reference signal. On the other hand, the second crank angle sensor 69 generates a pulse signal NE every 30 ° CA, which is used to detect the rotation speed.

The knocking detector 72 is of an electric vibration type or an acoustic vibration type, is installed in the cylinder block 10, and generates a vibration signal that is an index of knocking of the engine. A known knocking signal processing circuit 74 is arranged between the knocking detector 72 and the input port 64a, and a signal according to the presence or absence of knocking is input by comparing the background value of the peak value of the signal from the knocking detector 72. To be done.

Next, the operation of the control circuit 64 will be described with reference to the flowcharts of FIGS. FIG. 3 shows an ignition control routine, which is a crank angle interrupt routine executed by detecting the crank angle before compression top dead center of the cylinder to be ignited by the crank angle sensors 68 and 69. In step 80, the basic ignition timing θ _BASE is calculated. As is well known, the memory 64 has a data map of the basic ignition timing with respect to a combination of the engine speed NE and the intake air amount as a representative value of the engine-rotation speed ratio Q / NE, which is detected by the air flow meter 34. The basic ignition timing is calculated from the intake air amount Q and the engine speed NE by a complementary calculation.

In step 81, it is judged from the signal from the knocking detector 72 processed by the knocking signal processing circuit 74 whether or not there was knocking in the previous ignition of this cylinder.
When there is knocking, the routine proceeds to step 82, where the ignition timing retard correction amount θ _K is incremented by a predetermined angle β (for example, 0.5 °). Step 83 if there is no knock
Then, the ignition timing correction amount θ _K is decremented by the predetermined angle α. The process of step 83 can be executed after ignition without knocking continues for a plurality of times. By the above processing, the retard correction amount of the ignition timing is increased / decreased according to the presence or absence of knocking. Assuming that a fuel with a high octane number is used, knocking is unlikely to occur, so θ _K becomes smaller and ignition is performed near the base value. Conversely, in the case of a low octane fuel, so-called regular gasoline, the ignition timing correction amount θ _K becomes large, and ignition is performed away from the base value.

In step 84, the retard angle correction amount θ _{K is calculated} from the basic ignition timing θ _BASE.
The value obtained by subtracting is the execution advance value θ _EX .

In step 85, set the start time of energizing the igniter 63.
_Obtained from the execution advance value θ _EX calculated in 84, this energization start time is set in a compare register (not shown). When the set time comes, energization of the igniter 63 is started, and at the same time, a time matching interrupt routine (not shown) is started,
The power stop time is set in the compare register. It is well known that when the power supply stop time comes, the power supply to the igniter 63 is stopped, a high voltage is generated in the ignition coil 62, ignition is executed, and this time is the ignition timing calculated in step 84. is there.

FIG. 4 shows a supercharging pressure control routine, which can be performed in a time interruption routine executed at predetermined time intervals (for example, 50 msec). In step 87, the data of the intake air amount Q and the rotation speed NE are input. In step 88, the intake air amount-rotational speed ratio Q / NE is calculated. In step 89, it is judged which of the judgment areas χ divided for each rotation speed belongs. That is, in the embodiment, as shown in FIGS. 5 and 6, the five determination regions A to E are divided according to the number of revolutions. For the MPU64a, which judgment range χ is the current engine speed NE?
Identify if it belongs to.

In step 90, the threshold value θ _KREF (χ) that serves as a criterion for switching the supercharging pressure from High to Low in the current determination range χ identified in step 89 is calculated. That is, as shown in FIG. 5, each judgment range χ (AE) divided by the number of rotations.
The threshold value θ _KREF of the retard angle amount θ _K for switching the supercharging pressure from High to Low is stored in the memory every time, and the MPU 64a reads the threshold value in the current discrimination range. In the example, A, B, C,
The retard amount is set to 8 °, 7 °, 6 °, 5 °, 4 ° in each judgment area of D and E.

In step 91, calculation of a reference value that is the lower limit of the load for performing control to switch the supercharging pressure from High to Low is executed. That is, as shown in FIG. 6, each judgment region χ divided by the number of rotations
For each of (A to E), the data of the load lower limit reference value L _REF (χ) of the intake air amount-rotation speed ratio Q / NE as the load representative value is stored in the memory 64.
It is stored in a and the calculation of the load lower limit reference value L _REF according to the current rotation speed is executed. Here, the load lower limit reference value is set because there is a difference in the retard angle amount between high-octane gasoline and regular gasoline only in the high load operation range, so only in this operation range the supercharging pressure from High to Low This is because the control is performed and the boost pressure is not controlled in the light load range.

In step 92, it is judged whether or not the present engine load L as the intake air amount-rotational speed ratio Q / NE exceeds the lower limit value L _REF , that is, whether or not the control from the supercharging pressure High to Low is performed. Done. If No, bypass the following steps 93 to 95 and proceed to step 96. When the load is larger than the lower limit value, a Yes determination result is obtained, and the _routine proceeds to step 92 and step 93, where the current retardation amount θ _K is larger than the reference threshold value θ _KREF of the rotation range (χ) calculated in step 90. It is determined whether or not.
When the retard angle amount θ _K exceeds the judgment value θ _KREF and the supercharging pressure should be controlled to Low, the _routine proceeds from Step 92 to Step 95,
1 is written in the determination result storage register F (χ) in the rotation range χ. On the contrary, when the retard amount θ _K does not reach the judgment reference value θ _KREF and it is recognized that the high control of the supercharging pressure should be maintained, the _routine proceeds to step 94, where the register F
0 is written in (χ).

In step 96, the cumulative value ΣF (χ) of the values of the determination result storage register F (χ) in the rotation speed range A to E is calculated.

In step 97, it is determined whether the current setting of the supercharger is High or Low, that is, whether the bleed control valve 5 is open or closed. If the current turbocharger setting is High, step from step 97
Proceed to 98 to see if the cumulative value ΣF (χ) ≧ 3, that is, turn on the supercharger.
It is determined whether or not the number of rotation regions determined to be set to Low is 3 or more. If Yes, the routine proceeds to step 100, where a signal for turning off the solenoid 57 is output from the output port 64d. Therefore, the bleed control valve 56 is closed and the boost pressure is set to Low. If No in Step 98, proceed to Step 101, and operate the solenoid from the output port 64d.
A signal to turn ON 57 is issued. Therefore, the bleed control valve 56 is opened and the supercharging pressure is maintained at High.

When it is determined in step 97 that the current setting of the boost pressure is Low, the process proceeds to step 99, and it is determined whether the cumulative value ΣF (χ) is less than 1, that is, the boost pressure should be set to Low. It is determined whether or not the rotation range is 1 or 0. If No, the routine proceeds to step 100, where the bleed control valve is closed and the boost pressure setting is maintained at Low. If Yes, the routine proceeds to step 101, where the bleed control 56 is opened and the boost pressure is set to High.

The following table shows whether or not the retard angle amount θ _K exceeds the reference value θ _KREF (χ) in each judgment area A to E when operating after the passage of time from 1 to 5 with ○ and ×. is there. As explained in steps 98 and 99 in Fig. 4, when there are three or more regions where the retard amount exceeds the reference value (that is, x in the table below), the boost pressure is set to High and one or less. When, the boost pressure is set to High. Therefore, the boost pressure is set as shown at the right end of the table below.

In the example of the above table, the engine remains in the rotation range of C after 2 and continues to operate, and in this operation range C, the determination result varies in the operation ranges 1 to 5. In this example, boost pressure High
The number n of judgment regions when switching from the low to the low is set to 3, and the number n ′ of the judgment regions when returning from the boost pressure Low to the high is set to 1, and n−n ′ = 2. Therefore, even if there is a variation in the determination result in the C determination range, there is no variation in whether the boost pressure as a result of control is High or Low.
Therefore, supercharging pressure control without hunting is realized.

On the other hand, in the prior application, to show an example corresponding to the embodiment of the present invention, the supercharging pressure is set to Low when the number of rotation regions in which the retard amount exceeds the reference value exceeds 3 and is 2 or less. Hurging the boost pressure
It is controlled with h. That is, the number n of judgment areas when switching from the supercharging pressure High to Low and the number n of judgment areas when returning from the supercharging pressure Low to High are nn ′ = 1.
Therefore, the control results are as shown in the table below.

As is apparent from the above table, in the prior application, n−n ′ = 1, so if the judgment result of the C rotation range is varied in the operating range of 1 to 5, this directly becomes the judgment result of the supercharging pressure control. It appears, the supercharging pressure changes between High and Low with the passage of time, hunting occurs, which hinders drivability,
The present invention solves such a problem.

〔The invention's effect〕

According to the present invention, in which the set value of the retard angle amount at the time of switching from the supercharging pressure High state to the supercharging pressure Low state is set for each of a large number of determination regions, the supercharging pressure is set to High, A specific determination is made by setting the difference in the number of judgment areas in which the retard amount exceeds the set value by at least 2 from the number of operation areas in which the retard amount for returning the boost pressure to High exceeds the set value. Even if the determination result fluctuates in the range, the risk of hunting is eliminated, and engine drivability can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention. FIG. 2 is a block diagram of an embodiment of the present invention. 3 and 4 are flow charts for explaining the operation of the control circuit. FIG. 5 is a graph illustrating the setting of the reference value of the retard angle amount when switching the supercharging pressure between High and Low. FIG. 6 is a graph illustrating setting of a load lower limit value for performing supercharging pressure control. 17 …… Spark plug 34 …… Air flow meter 40 …… Turbocharger 47 …… Wastegate valve 50 …… Diaphragm mechanism 56 …… Bleed control valve 58 …… Solenoid 60 …… Distributor 62 …… Ignition coil 63 …… Igniter 64 …… Control circuit 68,69 …… Crank angle sensor 72 …… Knocking detector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F02D 43/00 301 B F02P 5/152 5/153 (56) Reference JP-A-62-150055 ( JP, A) JP 60-111031 (JP, A) JP 60-178973 (JP, A) JP 59-145330 (JP, A) Actual development Sho 60-192826 (JP, U)

Claims (2)

[Claims] 1. A supercharging pressure control device comprising the following components in an internal combustion engine with a supercharger having ignition timing control means for increasing / decreasing an ignition timing retard amount according to the presence or absence of knocking: The boost pressure control means for controlling the boost pressure obtained by means of high and low, the retard angle detection means for detecting the retard amount obtained by the ignition timing control means, depending on the operating condition factors affecting the retard amount. It is installed corresponding to a large number of divided judgment areas, and it determines whether the boost pressure is high or low by comparing the reference value of the retard angle set in each judgment area with the actual retard amount. Discriminating means, accumulating means for discriminating results by the respective discriminating means, and supercharging pressure to the supercharging pressure operating means when the actual retard amount exceeds the reference value of the retard amount in a predetermined number or more of judgment regions. A means to supply a signal to be lowered, the actual retard amount is the reference value of the retard amount Means for supplying a signal to the number of judgment region is to increase the boost pressure to the boost pressure actuating means in the case of at least 2 is small predetermined number or less than a predetermined number of the exceeding (99, 101). 2. The supercharging pressure control device according to claim 1, wherein the operating condition factor is a combination of an engine speed and a load.