JPH033924A - Supercharged pressure control device for engine - Google Patents

Abstract

PURPOSE:To prevent knocking and also secure good acceleration by sufficiently increasing the supercharged pressure rise correction quantity at the time of acceleration when high-octane fuel is used, and suppressing it when regular fuel is used. CONSTITUTION:The communicating ratio of an atomospheric pressure guiding passage 34 and a supercharged pressure guiding passage 35 to an actuator 33 is changed by the ON or OFF of a solenoid valve 36, a waste gate valve 32 is operated by the operation of the actuator 33, and the maximum supercharged pressure is changed. A control unit 41 judges the fuel based on the output from a knock sensor 42. When high-octane fuel is used, the solenoid valve 36 is turned on at the time of acceleration in the specific operation state, and the supercharged pressure is corrected upward. When regular fuel is used, the rise correction of the supercharged pressure is not performed at the time of acceleration in the specific operation state. Knocking is prevented when regular fuel is used, and also good acceleration is secured when high-octane fuel is used.

Description

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

(Prior Art) Many engines are designed to retard ignition timing when knocking is detected by a knocking sensor.

On the other hand, there is an increasing trend in recent engines to be able to use both high-octane fuel with a high octane number and regular fuel with a low octane number. In this case, it is necessary to identify whether the fuel is high-octane fuel or regular fuel, in order to divide the engine control values, such as ignition timing, into similar values for high-octane fuel and regular fuel. It has already been done to identify this fuel based on the output of a knocking sensor. More specifically, it is determined that the fuel is regular fuel when the amount of retardation of the ignition timing due to knocking, for example, becomes equal to or greater than a predetermined value.

Furthermore, although many modern engines use supercharging, it is also proposed to perform supercharging pressure correction that increases the supercharging pressure by a predetermined amount during specific operating conditions such as during acceleration. (See Japanese Unexamined Patent Publication No. 157017/1983).

By the way, in a system in which fuel is discriminated based on the output from a knocking sensor, it is conceivable to correct the boost pressure by increasing it during a specific operating state. however,
If the boost pressure increase correction amount is set according to high-octane fuel, knocking is likely to occur when regular fuel is used.To avoid this situation, boost It may be possible to set the pressure increase correction amount to be small in accordance with regular fuel, but in this case, good acceleration performance can be obtained when using high-octane fuel.

(Object of the invention) The present invention has been made in consideration of the above circumstances, and
Assuming that the type of fuel is determined according to knocking and the boost pressure is increased and corrected during specific operating conditions, it is possible to prevent knocking and ensure good acceleration when accelerating. An object of the present invention is to provide an engine supercharging pressure control device that satisfies the following.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention has the following structure. That is, as shown in the block diagram in FIG. 4, there is a knocking detection means for detecting engine knocking, and based on the output from the knocking detection means, it is determined whether the fuel being used is a high-octane fuel with a high octane number. , a fuel discrimination means for discriminating whether the fuel is a regular fuel with a low octane number, a supercharging means for supercharging the intake air of the engine, a supercharging pressure adjusting means for adjusting the supercharging pressure by the supercharging means; an operating state detection means for detecting an operating state; and a supercharging device that controls the supercharging pressure adjusting means to correct the supercharging pressure so that the supercharging pressure increases when the specific operating state is detected by the operating state detecting means. When the regular fuel is determined to be used by the pressure correction means and the fuel discrimination means, the supercharging by the boost pressure correction means is lower than when it is determined that the high-octane fuel is used. A suppressing means for reducing the amount of pressure increase correction.

(Operations and Effects of the Invention) In the present invention configured as described above, when high-octane fuel is used, the boost pressure increase correction amount is made sufficiently large (so that a good Acceleration performance can be ensured.Furthermore, when regular fuel is used, knocking can be prevented by suppressing the boost pressure increase correction amount during acceleration.

(Example) Examples of the present invention will be described below based on the attached drawings.

In FIG. 1, l is the main body of a reciprocating Otto type engine. As is known, this engine body 1 has a cylinder block 2, a cylinder head 3, and a piston 4 inserted into the cylinder block 2, and these three members 2, 3, 4 form a combustion chamber 5. It is defined.

An intake boat 6 and an exhaust boat 7 are opened in the combustion chamber 5, and both ports 6.7 are opened and closed at predetermined timings by an intake valve 8 or an exhaust valve 9 in synchronization with the engine output shaft. A spark plug 10 is provided in the combustion chamber 5.
is installed.

In the intake passage 21 connected to the intake boat 6, from the upstream side to the downstream side, an air cleaner 22, an air flow meter 23, a compressor wheel 24a of the supercharger 24,
Intercooler 25, throttle valve 26, surge tank 2
7. A fuel injection valve 28 is provided.

On the other hand, in the exhaust passage 31 connected to the exhaust boat 7, a turbine wheel 24b of the supercharger 24 is disposed. The exhaust passage 31 also includes the turbine wheel 2.
A bypass passage 31a is formed to bypass 4b, and a wastegate valve 32 is disposed in this bypass passage 31a. The wastegate valve 32 is pressure-operated by an actuator 33 during which the valve pressure, that is, the maximum supercharging pressure, is changed. The maximum supercharging pressure is changed by changing the communication ratio between the atmospheric pressure introduction passage 34 and the supercharging pressure introduction passage 35 with respect to (the pressure chamber of) the actuator 33 using the solenoid valve 36. In this case, when the valve 36 is turned on, the boost pressure is assumed to be small.

Reference numeral 41 in FIG. 1 is a control unit constituted by a digital or analog computer, more specifically a microcomputer. This control unit 4
In addition to the intake air amount signal from the air flow meter 23, signals from sensors 42, 43, 44, 45, and 49 are input to 1. The sensor 42 is a knock sensor that detects engine knocking. Sensor 43 is a water temperature sensor that detects engine cooling water temperature. sensor 44
is a rotational speed sensor attached to the distributor 46 to detect the engine rotational speed. The sensor 45 is an opening sensor that detects the opening of the throttle valve 26. The sensor 49 is an intake temperature sensor that detects the temperature of intake air.

Further, the control unit 41 outputs the signal to the solenoid valve 36 as well as to the igniter 47. That is, an ignition timing signal is output to the igniter 47, the igniter 47 cuts off the primary current of the ignition coil 48 at the timing of this ignition timing, and the high-voltage secondary current from the ignition coil 48 generated in conjunction with this, The signal is output to the spark plug 10 via the distributor 46 (ignition).

An overview of control by the control unit 41 will be explained.

First, the ignition timing is set to be different for high-octane fuel and regular fuel. That is, the basic ignition timing is set more advanced for high-octane fuel than for regular fuel. On the other hand, the supercharging pressure basically has the characteristics as shown by the solid line in Figure 2 (characteristics when the solenoid valve 36 is turned off), regardless of whether high-octane fuel or regular fuel is used.

When the engine speed is in a high rotation range greater than N3, as shown by β in FIG. 2, correction is performed to increase the boost pressure (solenoid valve 36 is turned ON). This boost pressure correction in the β region is performed for the following reasons. In other words, when the above-mentioned basic characteristics of boost pressure are set in accordance with the knocking limit in the low engine speed range and the combustion pressure limit in the medium engine speed range, the characteristics of the wastegate valve 32 determine the engine speed at high engine speeds. This is done to compensate for the fact that the boost pressure drops even though there is sufficient margin in the heat load limit in the range.

In addition, when acceleration is performed when the engine speed is between N1 and N2, only when high-octane fuel is used, the boost pressure is corrected to increase as shown in the β area in Figure 2. is performed, and when regular fuel is used, this boost pressure correction in the β region is not performed (the boost pressure increase correction amount is zero). Note that each boost pressure correction in the β region is performed for both high-octane fuel and regular fuel.

In the embodiment, determination as to whether the currently used fuel is high-octane fuel or regular fuel is made as follows. First, when the ignition switch is turned on, the ignition timing is set for high-octane fuel. If knocking occurs under such conditions, the ignition timing is retarded by a predetermined amount. When the amount of retardation of the ignition timing due to knocking exceeds a predetermined value, it is determined that the currently used fuel is regular fuel.

Regarding the details of the control by the control unit 41 mentioned above,
This will be explained with reference to the flowcharts in FIGS. 3A and 3B. Note that in the following explanation, S indicates a step.

First, the engine starts when the ignition switch is turned on, and by initializing with Sl, the retard angle 111GK for preventing knocking is set to O, the fuel flag is reset to O, and the acceleration flag is reset to O.

In addition, when the fuel flag is 0, it means high octane fuel,
1 means regular fuel. Further, when the acceleration flag is O, it means that the vehicle is not accelerating, and when it is ■, it means that the vehicle is accelerating.

In S2, the engine speed N, intake air amount Q, throttle opening TV, intake air temperature TA, and cooling water temperature TW are read. Then, fuel injection is performed using the engine rotation RN, intake air amount Q, and conversion factor fiK! (Pulse width) TP
is calculated.

After S3, it is determined in S4 whether the fuel flag is 1 or not. Initially, the fuel flag is reset to O, so the determination in S4 is No, and at this time S6
In this step, the basic ignition timing IGB is determined based on the ignition timing map for high-octane fuel, which is set using the engine speed N and the fuel injection amount TP as parameters. Thereafter, in S7, the final ignition timing TGF is calculated by subtracting the anti-knock retardation amount IGK from the basic ignition timing IGB, and in S8, ignition is executed at the timing of this final ignition timing IGF.

After S8, it is determined in S9 whether or not knocking is occurring, and if the determination in S9 is YES, the S
At step 10, the knocking countermeasure retardation amount IGK is increased by a predetermined amount ΔIG·1. Also, in the determination of S9, N
o, the retard angle i1 GK is reduced by a predetermined amount ΔIG·2 in Sit.

After the above-mentioned SIO or Sll, in S12, it is determined whether the above-mentioned retard amount IGK is larger than a predetermined value. Then, if the determination in S12 is YES,
In S14, the fuel flag is set to 1 (determination that the fuel is regular fuel). After the fuel flag is set to 1 in S14, the determination in S4 becomes YES, and the basic ignition timing IGB is determined based on the ignition timing map for regular fuel. Further, if the determination in S12 is NO, the fuel flag is reset to 0 in 313.

After 313, it is determined whether the conditions for performing boost pressure increase correction during acceleration are satisfied through the processes of S21 to S25. That is, the intake air temperature TA is at least a predetermined value, the cooling water temperature TW is at least a predetermined value, the throttle opening TV is at least a predetermined value, the fuel injection amount TP is at least a predetermined value, and the engine speed N is at a predetermined value or more. N1 and N2 shown in Figure 2
There is a time between. When all of these conditions are satisfied, the acceleration flag is set to 1 at 326. Next, in 328, it is determined whether or not the acceleration flag has just changed from O to 1. If the determination in S28 is YES, a timer is set in S29 (the boost pressure for acceleration is increased). set of times for correction). Further, if the determination in S28 is No, the timer is counted down in S30. Then, in S31,
It is determined whether the count value of the timer is O or not, and when the determination in S31 is NO, the solenoid valve 36 is turned on in S32 to increase the supercharging pressure as shown in the α region in FIG. An upward correction is made. Also, S31
When the determination is YES, it is determined in 333 whether or not the engine speed N is greater than N3. This 3
If the determination in step 33 is YES, the process moves to S32 and the second
The boost pressure increase correction shown in the region β in the figure is performed. and,
When the determination in S33 is NO, the solenoid valve 36 is turned off in S34, and the boost pressure increase correction is not performed.

After S14, that is, when it is determined that the currently used fuel is regular fuel, the process moves to S33 (only supercharging pressure correction in the β region is allowed).

In the above embodiment, when regular fuel is used, the boost pressure increase correction amount for acceleration is set to zero.
The boost pressure increase correction amount may not be set to zero, but may be set to, for example, 30% of the boost pressure increase correction amount when using high-octane fuel.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing boost pressure characteristics. FIGS. 3A and 3B are flowcharts showing control examples of the present invention. FIG. 4 is a block diagram showing the configuration of the present invention. 41: Control unit 42: Knock sensor 44: Distributor 47: Igniter 48: Ignition coil ■ = 0 1 4 2 3 6 Engine 2 spark plug: Intake passage: Supercharger: Waste gate valve: Actuator: Solenoid valve 1 N2 3 Engineering 〉Jishikashigo No. 3B ■ ■ ■ ■ Diagram

Claims (1)

[Claims] (1) Knocking detection means for detecting engine knocking; and determining whether the fuel being used is high-octane fuel with a high octane number or regular fuel with a low octane number based on the output from the knocking detection means. a supercharging means for supercharging the intake air of the engine; a supercharging pressure adjusting means for adjusting the supercharging pressure by the supercharging means; an operating state detecting means for detecting a specific operating state; a supercharging pressure correcting means that controls the supercharging pressure adjusting means to correct the supercharging pressure to increase when the specific operating state is detected by the operating state detecting means; When it is determined that fuel is being used, the amount of correction for increasing the boost pressure by the boost pressure correction means is made smaller than when it is determined that high-octane fuel is being used. An engine control device comprising: a suppression means;