JPH0445655B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for controlling ignition timing and boost pressure of an internal combustion engine equipped with a supercharger.

Prior Art In order to prevent knocking and engine damage caused by this even when fuels with different octane numbers are used, an octane number changeover switch is provided, and the driver can operate it to select the ignition timing map according to the type of fuel. This technique has already been proposed by the applicant and is publicly known (Japanese Patent Application Laid-Open No. 1983-1999).
(See Publication No. 57072).

However, in this type of technology, since the driver manually operates the octane number changeover switch, there is a risk that the driver may forget to change the switch or switch it incorrectly, making it impossible to select the optimum ignition timing map that matches the octane number. Additionally, if the fuel is changed to a fuel with a different octane rating midway through, it is difficult to judge at what point the changeover switch should be operated, and during that time, control is performed using an incorrect ignition timing map. There is a risk of it being stored away.

Furthermore, in a supercharged internal combustion engine, it is difficult to obtain the best output and fuel consumption rate for fuels with different octane numbers by simply selecting an ignition timing map.

OBJECT OF THE INVENTION Therefore, the present invention seeks to solve the above-mentioned problems of the prior art, and an object of the present invention is to ensure that good power output and fuel consumption are obtained even when using fuels with different octane numbers. The object of the present invention is to provide a control method that can prevent engine damage caused by knocking without fail.

Structure of the Invention The feature of the present invention that achieves the above-mentioned object is that it determines whether the gasoline being used is high-octane gasoline or regular gasoline, and when it is determined that it is high-octane gasoline, or high-octane treatment is performed. If it is determined that the turbocharger pressure will shift to high pressure, set the ignition timing using a high-octane ignition timing map, and if knocking occurs due to the set ignition timing, adjust the ignition timing. If knocking occurs continuously despite retardation correction and ignition timing retardation correction, perform high-octane processing to move to regular gasoline. If it is determined that the process should proceed to normal operation, set the turbocharger pressure to low pressure and set the ignition timing using the regular ignition timing map. If knocking does not occur at the set ignition timing, the ignition The timing will be advanced and corrected, and if the amount of advance correction exceeds a predetermined amount, the process will shift to high-octane processing, and if knocking occurs at the set ignition timing, the ignition timing will be retarded. be.

Example The present invention will be explained in detail below using the drawings.

FIG. 1 schematically shows a fuel-injected internal combustion engine with turbocharging as an embodiment of the present invention. In the same figure, 10 is 4 cycles 6
The cylinder block 12 of the cylinder internal combustion engine is a knock sensor attached to the cylinder block 10. The knock sensor 12 is a vibration detecting element such as a piezoelectric element or an electromagnetic element.

In the figure, 14 is a turbocharger main body;
16 is a compressor provided in the intake passage, 18
is a turbine installed in the exhaust passage. A wastegate valve 22 for controlling boost pressure is provided in the bypass passage 20 of the turbine 18 . The wastegate valve 22 is operated by a diaphragm actuator 24.
is operated by pressure fed from the intake passage downstream of the compressor 16 via the pressure conduit 26. The operating pressure of the actuator 24 will be described later (Fig. 2).
It is controlled by a signal from the control circuit 38, as shown in FIG.

In FIG. 1, numeral 28 is an octane number changeover switch that is provided in the driver's cab (not shown) and is manually operated by the driver, and 30 is an octane number indicator that is also provided in the driver's cab.

In FIG. 1, numeral 32 further indicates a distributor, and this distributor 32
are provided with crank angle sensors 34 and 36. The crank angle sensor 34 is for cylinder discrimination, and if this engine has 6 cylinders, it generates one pulse every time the distributor shaft makes one revolution, that is, every two revolutions of the crankshaft (every 720° CA). occurs. The occurrence position is set, for example, to a position slightly before the top dead center of the first cylinder. The crank angle sensor 36 generates 24 pulses each time the distributor shaft rotates, ie, every 30 degrees of crank angle.

Electrical signals from the knob sensor 12, changeover switch 28, and crank angle sensors 34 and 36 are sent to a control circuit 38. The control circuit 38 is further fed with a signal representative of the intake air flow rate Q from an air flow sensor 40 provided in the intake passage upstream of the compressor.

On the other hand, from the control circuit 38, the actuator 24
A signal is output to the inner solenoid 24a (FIG. 2). Further, from the control circuit 38, the igniter 42
An ignition signal is output to the spark plug 46 of each cylinder, and the spark current generated by the igniter 42 and the ignition coil 44 is transmitted to the spark plug 46 of each cylinder via the distributor 32.
distributed to. Furthermore, a display signal is also output to the display 30.

The engine is usually provided with various other sensors that detect operating state parameters, and the control circuit 38 also controls the fuel injection valve 48 and the like.
Since these are not directly related to the present invention, they will be omitted in the following description.

FIG. 2 shows the structure of the actuator 24 and wastegate valve 22 in detail.
Solenoid 24 in response to a signal from control circuit 38
When a is energized, the parallel cam 24b moves in the direction of the arrow, the contactor 24c moves to the right, and the initial length of the spring 24e that presses the diaphragm 24d becomes shorter. As a result, the wastegate valve 22, which is connected to the diaphragm 24d via the rod 23, remains closed until higher pressure is introduced into the chamber 24f, increasing the boost pressure. Conversely, when the solenoid 24a is deenergized, the parallel cam 24
Since b moves in the opposite direction of the arrow, the initial length of the spring 24e becomes longer, and as a result, the supercharging pressure decreases.

FIG. 3 is a block diagram showing an example of the configuration of the control circuit 38 shown in FIG. Air flow sensor 40
The voltage signal from is sent to the analog multiplexer 52 via the buffer 50, selected according to instructions from the microcomputer, and applied to the A/D converter 54, where it is converted into a binary signal.
It is taken into the microcomputer via the input/output port 56.

The pulses from the crank angle sensor 34 every 720 degrees of crank angle and the pulses every 30 degrees from the crank angle sensor 36 have buffers of 58 and 60, respectively.
and is sent to the microcomputer via the input/output port 62.

The output signal of the knock sensor 12 is sent to a peak hold circuit 66 and a rectifier circuit 68 through a circuit 64 consisting of a buffer for impedance conversion and a bandpass filter whose pass band is a frequency band (7 to 8 kHz) unique to knocking. . The peak hold circuit 66 takes in the output signal from the knock sensor 12 and holds the maximum amplitude only when a "1" level signal is applied from the microcomputer via the line 661 and the input/output port 62. . The output of the peak hold circuit 66 is sent to an analog multiplexer 70, selected according to instructions from a microcomputer, and applied to an A/D converter 72.
After being converted into a forward signal, it is taken into the microcomputer via the input/output port 62. The rectifier circuit 68 performs full-wave rectification or half-wave rectification of the output signal from the knock sensor 12. The rectified signal is fed into an integration circuit 74 and integrated with respect to time. Therefore, the output of the integrating circuit 74 is a value obtained by averaging the amplitudes of the output signals of the knock sensor 12. The output of the integrating circuit 74 is the analog plexer 70.
After being selectively applied to the A/D converter 72 and converted into a binary signal, it is taken into the microcomputer. However, A/D converter 7
The start of A/D conversion in step 2 is performed by an A/D conversion activation signal applied from the microcomputer via the input/output port 62 and line 76. Also,
When the A/D conversion is completed, the A/D converter 72 notifies the microcomputer of the completion of the A/D conversion via the line 78 and the input/output port 62.

The signal from the octane number switch 28 is input to the microcomputer via the input/output port 62.

On the other hand, when an ignition signal is output from the microcomputer to the drive circuit 80 via the input/output port 62, this is amplified and the igniter 42 is energized, and the ignition is controlled according to the duration and duration of the ignition signal. will be held.

Furthermore, when a 1-bit control signal is output from the microcomputer to the drive circuit 82 via the input/output port 62, this is converted into a drive current for the solenoid 24a, and the operating pressure of the actuator 24 is controlled.

When a 1-bit display signal is output to the drive circuit 83 via the input/output port 62, it is converted into a display signal, and the display 30 displays which octane rating is currently being controlled.

The microcomputer has the aforementioned input/output ports 56 and 62 and a microprocessor (MPU).
84, random access memory (RAM) 86,
It mainly consists of a read-only memory (ROM) 88, a clock generation circuit (not shown), a memory control circuit, a bus 90 connecting these, etc., and executes various processes according to the control program stored in the ROM 88. do.

The ROM 88 further stores in advance an ignition timing map for high octane fuel (hereinafter referred to as "high octane") and an ignition timing map for normal octane fuel (hereinafter referred to as "regular"). Ignition timing map is based on engine speed N and engine load Q/N
The optimal ignition advance angle is expressed with and as variables,
When the engine load Q/N is constant, the relationship between the high-octane ignition advance angle and the regular ignition advance angle is as shown in FIG. The ignition advance angle for high-octane engines is set to a larger value than that for regular engines.

Next, the operation of the microcomputer will be explained using a flowchart. However, how to determine the engine rotational speed N from the pulses every 30 degrees of crank angle from the crank angle sensor 36, how to detect whether or not knocking has occurred from the conversion output of the A/D converter 72, and how to detect whether or not knocking has occurred. After calculating the ignition timing correction amount for advancing and retarding the ignition timing in accordance with Since it is publicly known from Publication No. -167881 and the like, its explanation will be omitted in this specification.

FIG. 5 shows an interrupt processing routine that is executed every 120 degrees of crank angle, for example, at 90 degrees BTDC of the ignition cylinder. First, in step 100, it is determined whether high-octane control or regular control is currently being performed.
This determination is made by checking whether a specific flag _FSW is "1" or "0". This flag F _SW can also be reversed by the driver manually operating the octane number changeover switch 28.
It can also be automatically controlled from the MPU 84 side. If high-octane control is being performed, the process proceeds to step 101 and the supercharging pressure is set to a value on the high pressure side. In order to set the supercharging pressure to the high pressure side, it is sufficient to output a signal that energizes the solenoid 24a.
This causes the spring 24 to
The waste gate valve 22 does not open until the initial length of e becomes short and a high supercharging pressure is reached. In the next step 102, ignition timing calculation is performed using a high-octane ignition timing map.

In step 103, it is determined based on the output from the knock sensor 12 whether or not knocking has occurred. If knocking does not occur, this processing routine ends as is, but if knocking does occur, in step 104, it is determined whether or not it was determined that knocking occurred during the previous execution of the processing routine, that is, if knocking occurred continuously. Determine whether it is hot or not. If knocking did not occur last time, the ignition timing is retarded by a certain angle in step 105. This is, for example, to reduce the ignition advance angle correction amount θ _k by a certain value.
On the other hand, if knocking occurs continuously, that is, if knocking occurs again this time even though the retardation correction was made in step 105 previously, it is assumed that the octane number of the fuel is inappropriate and step 1 is performed.
At 06, the flag _FSW is inverted, and regular control is performed thereafter. Then, in step 107, a signal is outputted to the display 30 to indicate that regular control is being performed.

In step 100, if it is determined from the flag F _SW that regular control is being performed,
Proceeding to step 108, the boost pressure is set to a value on the low pressure side. This can be done by outputting a signal that de-energizes the solenoid 24a. In this way, in the case of regular fuel with a low octane number, the supercharging pressure is set low, and in the case of high-octane fuel with a high octane number, the supercharging pressure is set high. The reason is the 6th
As shown in figure a, when boost pressure is increased, with regular fuel with an octane rating of 90, the maximum torque generation ignition advance angle will fall within the knocking generation area shown by the diagonal line, and if it is not a high-octane fuel with an octane rating of 98, the maximum torque ignition will not occur. Unable to gain advance. Conversely, when using a high-octane engine, it is possible to increase the boost pressure and generate greater torque. When using a regular with an octane rating of 90, if the supercharging pressure is set low as shown in Figure 6b, the ignition advance angle for maximum torque generation can be obtained before the knocking generation region. Next, in step 109, ignition timing is calculated using the regular ignition timing map.

In step 110, it is determined whether or not knocking has occurred. If knocking has occurred, it is determined in step 111 whether or not knocking has occurred during the previous execution. If knocking did not occur last time, the ignition timing is retarded by a certain angle in step 112. As mentioned above, this reduces the ignition advance angle correction amount θ _k by a certain value. On the other hand, if knocking occurs continuously, that is, if knocking occurs again even though the ignition advance was previously retarded in step 112, it is determined that a trouble has occurred, and the ignition timing is adjusted in step 113 to ensure that the ignition timing never stops. Perform processing to fix the value to a value that will not occur.

If it is determined in step 110 that no knocking has occurred, the process advances to step 114 and checks whether or not it was determined that knocking has occurred the previous time the process of step 110 was performed. If knocking occurred last time, go to step 115.
Proceed to advance the ignition timing by a certain angle. This is achieved by increasing the ignition advance angle correction amount θ _k by a certain value. Next, in step 116, a count value n indicating how many times advance angle correction has been performed is calculated.
is set to “1”.

If it is determined in step 114 that knocking did not occur last time, the process proceeds to step 117.
The process advances to step 115, where the ignition timing is advanced by a certain angle, and then, at step 118, the count value n is incremented by "1". Next step 11
At step 9, it is determined whether or not the count value n has exceeded a certain value _n0 . If n≧ _n0 , the flag F _SW is inverted at step 120, and high-octane control is thereafter performed. Then, in step 121, a message indicating that high-octane control is being performed is displayed on the display 30.

As described above, in this embodiment, even if the ignition timing is controlled using a high-octane ignition timing map with a high boost pressure, and the ignition timing is retarded due to the occurrence of knocking, if knocking still occurs. The system automatically switches the boost pressure to low pressure and the ignition timing map to the regular one. In addition, the boost pressure is set to low, and the ignition timing is controlled using the regular ignition timing map, so that knocking does not occur.If knocking still does not occur even after advancing the ignition timing _n0 times, supercharging is performed. It automatically switches the pressure to high pressure and the ignition timing map to a high-octane one. Note that if knocking still occurs even after performing retardation correction due to low boost pressure and the ignition timing map for regular engine, the ignition timing is fixed as it is assumed that some kind of failure has occurred.

Therefore, even if the driver accidentally operates the octane number changeover switch, the boost pressure and ignition timing map can be automatically selected, so that the best output and fuel consumption can always be obtained.

Effects of the Invention As explained in detail above, according to the present invention, it is possible to always obtain good output and fuel consumption even when using fuels with different octane numbers, and moreover, it is possible to prevent engine damage caused by knocking. And it can be reliably prevented.

[Brief explanation of drawings]

1 is a diagram schematically showing an example of an internal combustion engine to which the present invention is applied, FIG. 2 is a detailed view of the actuator portion of FIG. 1, and FIG. 3 is a block diagram of the control circuit of FIG. Figure 4 is an ignition advance characteristic diagram, Figure 5 is a flowchart of the control circuit processing routine, and Figure 6 is a flowchart of the processing routine of the control circuit.
Figures a and 6b are diagrams showing the relationship between torque characteristics and knocking occurrence region with respect to ignition advance angle. 10... Cylinder block, 12... Knock sensor, 14... Turbo charger, 16... Compressor, 18... Turbine, 20... Bypass passage, 22... Waste gate valve, 24... Diaphragm type actuator, 24a... Solenoid , 26... Pressure conduit, 28... Octane number selection switch, 30... Display, 32... Distributor, 34, 36... Crank angle sensor, 38... Control circuit, 40... Air flow sensor, 42... ...igniter, 44...ignition coil,
46... Spark plug, 54, 72... A/D converter, 64... Buffer and filter circuit, 66...
... Peak hold circuit, 68 ... Rectifier circuit, 74
...Integrator circuit, 84...MPU, 86...RAM,
88...ROM.

Claims (1)

[Scope of Claims] 1. It is determined whether the gasoline being used is high octane gasoline or regular gasoline, and if it is determined that it is high octane gasoline or it is determined that it is determined that the process should be shifted to high octane gasoline. If this occurs, set the turbocharger pressure to high pressure, set the ignition timing using the high-octane ignition timing map, and if knocking occurs due to the set ignition timing, retard the ignition timing and correct the ignition timing. If knocking continues to occur despite retarding the timing, move to regular processing.Execute high-octane processing.If it is determined that it is regular gasoline, or shift to regular processing. If this is determined to be the case, set the turbocharger pressure to a low pressure, set the ignition timing using the ignition timing map for regulars, and if knocking does not occur at the set ignition timing, advance the ignition timing. However, if the advance angle correction amount exceeds a predetermined amount, the process shifts to high-octane processing, and if knocking occurs at the set ignition timing, the ignition timing is retarded. Control method for internal combustion engine with feeder.