JPH0321748B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device having a knock sensor for detecting knocking in an internal combustion engine.

In recent years, various knock sensors and ignition timing control devices using knock sensors have been devised and announced, but all of these sensors and devices can reliably detect knocking in the entire load range of the internal combustion engine and ensure proper ignition timing. Control was difficult.

The present invention relates to knock feedback control in an ignition timing control system using a microcomputer.

The vibration signal generated by the knock sensor (hereinafter referred to as the output signal) may be caused by variations in the sensor itself or mechanical vibrations (hitting noise) caused by the valve seating of the internal combustion engine (hereinafter referred to as the engine), in addition to the knocking signal generated during knocking. Various noises were often picked up, and it was often determined that knocking was occurring even when no knocking was occurring.

In view of the above problems, the present invention focuses on the fact that the period in which knocking occurs is concentrated at a specific crankshaft angle or time of the engine, and incorporates mechanical vibrations caused by engine valve seating into a microcomputer control program. The section in which knocking occurs and knocking occurs, that is, the gate start timing and gate end timing for gating the output signal from the knock sensor, can be determined independently using a map stored in advance in the storage device based on the operating conditions of the internal combustion engine, especially the rotation speed information. It is equipped with means for reliably detecting and storing the occurrence of knocking for each cylinder by controlling the operation of each knock sensor input circuit according to the respective operating conditions in consideration of the positional relationship between each knock sensor and each cylinder. An object of the present invention is to provide an ignition timing control device that detects knocking in an optimal period using an optimal knock sensor for each cylinder, and sets the optimal ignition timing for each cylinder under the control of a control program.

FIG. 1 is a configuration diagram of an engine incorporating an embodiment of the ignition timing control device according to the present invention. 1 is a 6-cylinder engine, 2 is an air cleaner, and 3 is an intake air amount sensor, which is an analog sensor according to the amount of intake air. This is a well-known device that generates an output voltage. 4A-4F
5 is a spark plug, and 5 is a distributor which serves to distribute ignition energy to each cylinder, and also has a built-in sensor for the crankshaft angle of the engine and a sensor for identifying the cylinders. 5a
The latter is a cylinder signal that indicates a cylinder discrimination signal, and specifically indicates the top dead center of the compression process of the 6th cylinder (the cylinder to which the 4F plug is installed). 5b
is the former, that is, an angle signal indicating the rotation angle of the crankshaft, and specifically, a signal is output every 30 degrees of the crankshaft. Hereinafter, 5 will be referred to as a rotation angle sensor. 6A
and 6B are knock sensors that detect the occurrence of knocking in the engine 1. 6A is placed between the first and second cylinders, and 6B is placed between the fifth and sixth cylinders to effectively detect knocking that occurs in each cylinder. I have made it possible. (6A is the knock sensor A, 6
B is called knock sensor B). 7 is a transistor type ignition device (hereinafter referred to as an igniter) that generates ignition energy. Reference numeral 8 denotes a control device that receives information on the intake air amount, rotational speed, crankshaft angle, and cylinder position through the intake air amount sensor 3 and rotation angle sensor 5, and controls the knocking of each cylinder using knock sensor A and knock sensor B. It takes in the occurrence information and sets the optimal ignition timing for each cylinder.

FIG. 2 is a detailed internal view of the control device 8, and the control device 8 is composed of a microcomputer. 1
00 is a central processing unit (CPU) using a microprocessor, 101 is a random access memory (RAM) used as a program work area, 102 is a read-only memory (ROM) that stores a control program, 103 is a CPU,
RAM, ROM, and input/output devices (I/
Addresses and data of each component are transferred via a common bus that connects O). 104
105 is an input circuit that shapes the cylinder signal 5a generated by the rotation angle sensor into a voltage signal that can be received by the internal logic, 105 is an input circuit that shapes the angle signal 5b, and 106 also receives the outputs of the input circuits 104 and 105. A timing generator that generates a crankshaft timing signal generates rotation speed information based on the cycle of the angle signal, and transmits it to the common bus 103 together with cylinder information according to the control program. 1
06a is the cylinder signal, 106b is the angle signal, 1
06c indicates a signal of rotational speed information including cylinder information. 107 is an input circuit that processes the signal of knock sensor A6A, and 108 is knock sensor B6B.
This is an input circuit that processes signals. A gate signal generator 109 controls the operation of the input circuits 107 and 108 based on the cylinder signal and angle signal output from the timing generator 106 and the operation period information of the input circuits 107 and 108 set by the control program. Gate signals 109a and 109b are generated. Therefore, the input circuits 107 and 108 constitute a gate circuit together with the gate signal generator 106, and the signal level (for example, peak level) of the knock sensor during the gate period is maintained. 110 is a multiplexer that selects analog information from the intake air amount sensor 3 and input circuits 107 and 108 according to a control program; 111 is an A/D (analog-digital)
A converter converts the analog information selected by the multiplexer into digital information and connects it to the common bus 10.
Transfer to 3. The angle signal 106b is sent to the CPU 100
is input to the interrupt input port of the interrupt processing program. 112 is the output register of CPU10
0 is the ROM10 based on the information of the intake air amount sensor 3 and rotation angle sensor 5, and the information of the knock sensors 6A and 6B.
The calculation is performed according to the control program stored in 2, and the result is transferred to the output register 112 to set the ignition timing.

Reference numeral 113 is an amplifier for amplifying the ignition timing signal output from the output register, and ignition energy is generated by the igniter 7 in accordance with the output signal of the amplifier 113.

The details of the present invention will be explained using FIG. 3, FIG. 4, and FIG. 5. In the time chart of FIG. 3, the cylinder signal 5a is 6 of engine 1.
The angle signal 5b is a crankshaft angle (30°A) signal, and the symbols #1 to #6 indicate the compression top dead center of each cylinder. The timing generator 106 generates a cylinder signal 5a and an angle signal 5b.
are converted into a cylinder signal 106a and an angle signal 106b, respectively. That is, the cylinder signal 106a rises at the compression top dead center of the No. 6 cylinder, and the angle signal 106b rises at 30.
The relationship is related to the timing of rising for each °C.
Gate signals 109a and 109b are control signals for an input circuit that processes signals from the knock sensor, and are activated (ON) at logic "1" level and stopped (OFF) at logic "0" level. The ON and OFF control signals are calculated under the control program based on the rotation speed information and cylinder information and are sent to the gate signal generator 1.
09, and gate signals 109a and 109b are generated. Reference numeral 112a is an ignition signal generated from an output register, which is calculated and transferred under the control of a control program based on information from the intake air amount sensor 3, rotation angle sensor 5, and knock sensors 6A, 6B.

FIG. 4 shows a flowchart of the control program, particularly the interrupt processing program for calculating the ignition timing. An interrupt processing program is started every 30°A rotation of the crankshaft by the angle signal 106b. When the angle signal is input to the interrupt input of the CPU 100, the 30°C A interrupt is activated at step 210 in FIG.
6, the cylinder signal 106a and rotation speed information 106b are read and temporarily stored in the RAM 101. At step 212, the cylinder signal 106a is set to "0" or "1".
If the cylinder signal 106a is "1", it is determined that the compression top dead center of the No. 6 cylinder is reached, and the RAM 101
The contents of the specific address "CL counter" (angle pulse signal counter) are cleared to zero, and the cylinder signal 106 is cleared.
If a is "0", the contents of the CL counter are incremented by one. By performing this operation, a specific number can be assigned to each cylinder as shown in the CL counter time chart in Figure 5. Then, in step 215, the content of the CL counter is 2.
When the relationship of +4×N (N; 0, 1, 2...) is satisfied, the next cylinder to be ignited is BTDC60.
It can be seen that this is before ℃A. Looking at it from another perspective, it can be seen that 60°C has passed since the top dead center of the previous ignition cylinder. When 2+4・N is satisfied, the ignition advance angle is calculated in order to ignite the next cylinder. If the relationship is not satisfied, there is no need to calculate the ignition advance angle, so step 225 RTI (return interrupt) is executed.
ends the interrupt program. step
At step 216, it is determined in which cylinder the previous ignition took place by referring to the contents of the CL counter, a knock sensor closer to the cylinder in the explosion process is selected by activating the multiplexer 110, and the A/D
The converter 111 is used to read the signal level of the knock sensor, and the cylinder information (contents of the CL counter) is stored in the RAM 101 as an index (parameter) to be used for the next ignition control. Step 217
Based on the rotational speed information read in step 211, the map written in advance in the ROM 102 is indexed to determine the period (i.e., the period in which hitting noise due to valve seating, etc.) is avoided from the knock sensor signal (i.e., (equivalent to the periods t ₁ to t ₂ and t ₃ to t ₄ of the gate signals 109a and 109b) are determined and the periods are set in the gate signal generator 109.

In step 218, the intake air amount is detected by starting the multiplexer 110 and A/D converter 111, and in step 219, ignition is performed based on the rotational speed information detected in step 211 and stored in the RAM 101. Calculate the basic amount of advance angle θ ₀ .

In step 220, the cylinder to be ignited next time is
The signal level of the knock sensor during the previous explosion process is indexed from the RAM 101 using the contents of the CL counter as an index, and if it is determined that knocking has occurred, a knocking correction amount θ _KNK is calculated in step 221. . If it is determined that knocking does not occur, step 222
Let θ _KNK = 0 in .

In step 223, the next ignition advance angle _θig is calculated.

In this embodiment, θ _ig =θ _O +θ _KNK .

In step 224, the value of θ _ig is set in the output register 112 to perform ignition advance control, and in step 225 RTI, the interrupt program is terminated.

In the first embodiment, cylinder discrimination is performed using an angle signal 10.
This is done in the interrupt processing program triggered by interrupt activation by 6b.

The device configuration of the second embodiment of the present invention is similar to that of the first embodiment shown in FIGS. We decided to read only the rotation speed information in , and cylinder discrimination is not performed in interrupt processing, but is processed in the main routine (normal program).
The purpose is to reduce the interrupt overhead of the CPU 100.

FIG. 6 shows a flowchart of the cylinder discrimination processing section inserted into the main routine of the second embodiment. In the flowchart of the interrupt processing program of the second embodiment, steps 212, 213, and 214 in FIG. 4 may be omitted.

In the present invention, based on the output information of the rotation angle sensor, a cylinder in the explosion stage is detected by program processing, and the output signal is read from a knock sensor that is optimal for detecting knocking in the cylinder located close to the cylinder. This reading is determined based on the operating conditions of the internal combustion engine to determine the optimum detection period (i.e., the gate start timing and gate timing for gating the output signal from the knock sensor) to avoid the influence of noise such as mechanical vibrations caused by the seating of valves in the internal combustion engine. The termination timing is set independently for each knock sensor using a map stored in advance in the storage device based on the operating conditions of the internal combustion period, especially rotation information. Knocking detection is performed for each cylinder, and by detecting knocking in each cylinder within the optimum period using the optimum knock sensor for knocking detection, accurate knocking detection is performed for each cylinder. Ignition timing can be set.
In addition, noise is generated not only by mechanical vibration caused by the valve seating, but also by a complex interaction of mechanical vibration caused by the valve seating and a number of factors, so the optimal gate section is determined by compatibility tests with various internal combustion engines. Generally, depending on the result, the gate period cannot be set only by a linear curve depending on the rotation speed. However, according to the present invention, it is possible to arbitrarily set the optimum gate section corresponding to the rotation speed of each engine through compatibility tests with various engines.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an engine incorporating an embodiment of the ignition timing control device according to the present invention, and FIG.
3 is a time chart of each part of the ignition timing control device, and FIG. 4 is an interrupt processing program used in the first embodiment of the ignition timing control device. 5 is a time chart of the angle pulse signal counter in the ignition control device, and FIG. 6 is a flow chart of the cylinder discrimination processing section in the normal program used in the second embodiment of the ignition control device. . 1... 6-pressure cylinder engine, 2... Air cleaner, 3... Intake amount sensor, 4A-4F... Spark plug, 5... Distributor with built-in rotation angle sensor, 6A, 6B... Knock sensor, 7 …
...Igniter, 8...Control device, 100...
CPU, 101...RAM, 102...ROM, 1
03...Common bus, 104, 105, 107,
108...Input circuit, 106...Timing generator, 109...Gate signal generator, 110...Multiplexer.

Claims (1)

[Scope of Claims] 1. A rotation angle sensor that detects the rotation angle of the crankshaft of an internal combustion engine and determines the cylinder; and a rotation angle sensor that corresponds in position to each cylinder and that detects knocking of the internal combustion engine and that corresponds to the number of cylinders. A cylinder in the explosion stage is detected by a small number of knock sensors provided, a gate means for gating the output signal of the knock sensor, an intake air amount sensor for detecting the intake air amount of the internal combustion engine, and a detection signal from a rotation angle sensor. The output signal of the knock sensor located near the relevant cylinder is read and stored via the gate means, knocking is detected for each cylinder from the stored knock sensor output signal, and this detection result is used together with the rotation angle sensor and intake air amount sensor. and an output circuit that drives the ignition device based on the calculation results of the data processing means,
The data processing means determines the start time when the output signal of the knock sensor should be gated, based on the rotational speed information of the internal combustion engine obtained from the output of the rotation angle sensor, using a map stored in advance in the storage device of the data processing means. The ignition timing control device is characterized in that the gate end times are independently determined, and the gate means gates the knock sensor output during the period from the determined gate start time to the gate end time. 2. The ignition timing control device according to claim 1, wherein the data processing means calculates ignition timing for each cylinder.