JP3331880B2 - Control device using microcomputer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and a control device for controlling a specific control object using a microcomputer, and more particularly to an ignition timing of an ignition device for an internal combustion engine and an injector of a fuel injection device for the internal combustion engine. The present invention relates to a control method and a control device suitable for controlling the control.

[0002]

2. Description of the Related Art When a microcomputer having a nonvolatile memory in a microprocessor is used to control the ignition timing of an internal combustion engine and the injector of a fuel injection device using the microcomputer, the specification of the engine can be changed, This is inconvenient because it is not possible to cope with a case where it is necessary to change a program or control data in order to cope with a change in required characteristics. Therefore, in this type of control device, a program and control data required for control are stored in a nonvolatile external memory, and a signal line (address / data bus) is connected between the external memory (ROM or EEPROM) and the microprocessor. ). With this configuration, the program and control data can be easily changed by replacing the ROM, and the program and control data can be easily rewritten by using an EEPROM as the external memory.

FIG. 4 shows an example of the configuration of a control device 1 for an internal combustion engine using a microcomputer. In FIG. 4, reference numeral 2 denotes a microprocessor 3 in which a CPU, a timer, an internal RAM, an interrupt controller and the like are integrated into one chip. And a external memory 4 such as a ROM (read only memory) storing programs and control data, an EEPROM (rewritable nonvolatile memory), and the like. The microprocessor 3 is mounted on a circuit board (not shown) via a connector or directly, and the microprocessor 3 and the external memory 4 are connected through a signal line (address / data bus line) 5 formed on the circuit board. ing.

[0004] The control device 1 includes an ignition coil 6 constituting an output portion of an ignition device for an internal combustion engine and a solenoid coil 7 of an injector 7 of a fuel injection device for supplying fuel to the internal combustion engine.
and an exciting coil 10b of an electromagnetic relay 10 having a contact 10a for turning on and off a current supplied from a battery 8 to a motor 9 of an actuator for driving an exhaust timing control valve and the like.

[0005] An ignition circuit 11 for controlling the primary current of the ignition coil 6 is provided in the control device 1.
1 and an ignition coil 6 constitute an ignition device for an internal combustion engine. The ignition circuit 11 causes a sudden change in the primary current of the ignition coil 6 when the ignition signal Vi is given from the microprocessor 3 to induce a high voltage for ignition in the secondary coil of the ignition coil. This high voltage is applied to a spark plug 12 attached to a cylinder of the engine. The ignition circuit 11 is, for example, a capacitor provided on the primary side of the ignition coil and charged to one polarity by a power supply (not shown). A switch element for discharging through the coil, and discharging a charge of the capacitor through the primary coil of the ignition coil to induce a high voltage for ignition in the secondary coil of the ignition coil.

The control device 1 also includes an injector drive circuit 13 for turning on and off a current supplied to a solenoid coil 7a of the injector 7, and a relay drive circuit 14 for turning on and off an excitation current supplied to an exciting coil 10b of the relay 10. Is provided.

The injector drive circuit 13 supplies a drive current to the solenoid coil 7a of the injector 7 while receiving the rectangular drive signal Vd from the microprocessor 3. The timing at which the injector 7 starts fuel injection is determined by the rise time of the drive signal Vd, and the time (fuel injection amount) during which the injector 7 injects fuel is determined by the signal width of the drive signal Vd.

The relay driving circuit 14 supplies an exciting current to the exciting coil 10b of the relay according to a control signal given from the microprocessor 3. The relay 10 closes its contact 10a when an exciting current is applied, and
Turn on electricity.

[0009]

In the control device 1 as described above, a large electric noise (ignition noise) is generated because a discharge current flows through the secondary coil of the ignition coil when the internal combustion engine is ignited. Then, there is a possibility that this noise may enter the control device 1 through the ground circuit of the circuit board and get on the signal line 5.

The solenoid coil 7 of the injector 7
When the drive current supplied to the control signal a is cut off, a high noise voltage is induced in the solenoid coil 7a, and this noise voltage may enter the control device through a ground circuit or a power supply circuit and get on the signal line 5. is there.

Further, even when the exciting current of the relay 10 is cut off, a high noise voltage is induced in the exciting coil 10b, so that noise may enter the signal line 5.

If noise is applied to a signal line connecting the microprocessor 3 and the external memory 4, the microcomputer may malfunction. Conventionally, a signal provided on a circuit board on which the microprocessor 3 and the external memory 4 are mounted is provided. By making the length of the wire 5 as short as possible, it is difficult for the noise to ride on the signal line, or by devising the pattern of the ground circuit and the power supply circuit provided on the circuit board, the noise is hardly penetrated into the signal line, Measures have been taken to make it difficult for noise to enter by making the substrate on which the microprocessor 3 is mounted multi-layered.

As shown in FIG. 5, the signal line 5 includes resistors R1, R2,..., Rn and capacitors C1, C2,.
A method of removing noise on the signal line 5 by connecting Cn to lower the impedance of the signal line has also been considered.

If the method of shortening the signal line 5 or devising the pattern of the ground circuit and the pattern of the power supply circuit among the above measures is used, the degree of freedom in designing the circuit board is reduced. There is a problem in that the design of the substrate becomes difficult and the cost increases. In addition, there is a problem in that the production of the multilayered substrate is troublesome and the cost is remarkably increased.

Further, as shown in FIG. 5, when a method of connecting a resistor or a capacitor to lower the impedance of a signal line is employed, a large number of circuit components are required, which not only increases the cost but also increases the cost of the circuit board. However, there was a problem that the size became large.

Even if the above measures are taken, it is difficult to completely prevent noise from entering the signal line 5, and especially since ignition noise contains a very wide range of frequency components, It was difficult to completely prevent the intrusion into the city.

The above problem is not unique to a control device for an internal combustion engine, and a microcomputer in which a microprocessor and a nonvolatile external memory storing programs and control data are connected by a signal line. This is a common problem when controlling a specific control object in which electrical noise is generated by using the control signal.

An object of the present invention is to provide a control device capable of controlling a control target without being affected by noise on a signal line connecting a microprocessor and an external memory. It is in.

[0019]

According to the present invention, a period in which electrical noise is generated using a microcomputer in which a microprocessor and a non-volatile external memory storing programs and control data are connected by a signal line. The present invention relates to a control method for controlling a specific control target that can be predicted. In the present invention, communication between a microprocessor and an external memory is stopped during a period in which noise is expected to be generated from the control target. I did it.

As described above, if the control operation is interrupted by stopping the communication between the microprocessor and the external memory during the period in which the control object is expected to generate noise, the noise on the signal line Is not affected by
An erroneous control operation due to noise can be prevented. In addition, since it is not necessary to devise a circuit pattern of a circuit board or to add a circuit component for lowering the impedance of a signal line, the cost is increased and the circuit board is enlarged. Can be prevented.

To stop communication between the microprocessor and the external memory during a period in which noise is expected to be generated from the control target, for example, a time slightly earlier than the timing at which the control target generates electrical noise Is detected as the communication stop timing, and when the communication stop timing is detected, the communication between the microprocessor and the external memory is prohibited and the measurement of the communication stop time is started, and when the communication stop time is measured, Communication between the microprocessor and the external memory may be permitted.

A control device used to carry out the above method includes a microprocessor having a CPU, a timer, an internal RAM, and an interrupt controller, and a non-volatile external memory storing programs and control data,
A control device for controlling a specific control target capable of predicting a timing at which electrical noise occurs using a microcomputer in which a CPU and an external memory are connected by a signal line, the control device comprising: Communication stop timing detection means that detects a time slightly earlier than the timing at which the target generates electrical noise as communication stop timing, and sets a communication stop time to a timer when the communication stop timing is detected by the communication stop timing detection means Timer setting means for performing communication between the microprocessor and the external memory when communication stop timing is detected, and prohibiting communication between the microprocessor and the external memory when the timer completes measuring the communication stop time. It can be configured by providing a permitted communication control means.

The above-described control device also executes a loop program for looping a program stored in the internal RAM a certain number of times after the microcomputer is started up.
A loop program writing means for writing to M, a communication stop timing detecting means for detecting a time slightly earlier than a timing at which the control object generates electrical noise as a communication stop timing, and a communication stop timing detected by the communication stop timing detecting means A communication stop timing loop processing means for executing a loop program after prohibiting communication between the microprocessor and the external memory when the loop is executed, and a communication between the microprocessor and the external memory when a predetermined number of loops by the loop program are completed. It can also be configured by providing communication permission means for permitting communication.

The control object is, for example, an ignition device for an internal combustion engine. When the control target is an ignition device for an internal combustion engine, the timing at which electric noise occurs is the ignition timing. Further, when the control target is the injector of the fuel injection device for an internal combustion engine, the timing at which the electrical noise occurs is the timing at which the energization to the solenoid coil of the injector is cut off.

The signal line may be formed as a circuit pattern on a circuit board, or may be a signal cable connected to the circuit board via a connector.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a configuration of a microcomputer part of a control device according to the present invention. In FIG. 1, reference numeral 3 denotes a microprocessor (microchip computer), and reference numeral 4 denotes an external memory. . In this example, similarly to the example shown in FIG. 4, the ignition device for the internal combustion engine, the fuel injection device for the internal combustion engine, and the relay for turning on and off the power supply to the motor of the actuator for driving the exhaust timing adjusting valve and the like are controlled. It is assumed that these control targets are controlled by a microcomputer.

The illustrated microprocessor 3 has a CPU 3
a, input / output interface 3 including A / D converter, etc.
b, first and second timers 3c and 3d, RAM 3e,
The interrupt controller 3f and the like are integrated into one chip, and are attached to the circuit board 20 via a connector or directly. The external memory 4 includes a ROM or an EEPROM and a RAM, and is attached to the circuit board 20 via a connector. A signal line (address / data bus) formed on the circuit board 20 between the CPU 3a of the microprocessor 3 and the external memory 4.
5 are connected. The outputs of various sensors necessary for control and a position detection signal obtained by shaping a pulse signal generated by a pulsar coil in a signal generator mounted on the internal combustion engine are input to the CPU 3a. Usually, the signal generator comprises an inductor-type generator, and the pulsar coil generates a first pulse signal at a first rotation angle position (reference position) of a reference engine, and generates a first rotation angle position. A second pulse signal is generated at a second rotation angle position delayed by a certain angle. These pulse signals are changed by a waveform shaping circuit (not shown) in a first rotation angle position and a second rotation angle position.
And converted into second position detection signals Vp1 and Vp2, and input to the CPU 3a via the interface 3b. The first rotation angle position is set at a position advanced from the top dead center of the engine, and the first position detection signal Vp1 is used to determine the timing to start measuring the ignition timing. The second rotation angle position is set to a constant rotation angle position (minimum advance angle) near the top dead center of the engine, and the second position detection signal Vp2 determines the ignition timing of the engine at low speed. Used for

The ROM of the external memory 4 stores a program necessary for controlling each control object and control data including constants, mathematical expressions, arithmetic maps, and the like necessary for control. The RAM 3e in the microprocessor 3
Before the control operation is started after the microcomputer is started, a program necessary for controlling the interrupt controller 3f from the external memory 4 and constants necessary for stopping communication between the CPU and the external memory are provided. Is read. The CPU 3a reads and executes a program stored in the external memory when the interrupt to the external memory is permitted by the interrupt controller 3f, thereby executing
Calculation of ignition timing, calculation of fuel injection time, and the like are performed.

When a control target controlled by the microcomputer generates electric noise, the noise rides on the signal line 5 to change the contents of the program read by the CPU or to make it impossible to read the program. May occur or the control operation may be locked.

Therefore, the present invention focuses on the fact that the timing at which noise is generated can be accurately predicted in a controlled object controlled by a microcomputer. By stopping the communication between them, the influence of noise was eliminated.

For example, in the case of an ignition device for an internal combustion engine, ignition noise is generated when a high voltage for ignition is generated in the secondary coil of the ignition coil 6 (see FIG. 4) at the ignition timing. When the ignition timing is controlled by a microcomputer,
The ignition timing at each rotation speed of the engine is calculated in the form of the time (ignition timing measurement time) Ti required for the engine to rotate from the reference position to the ignition position at that rotation speed, and is calculated as shown in FIG.
As shown in (A), when the first pulse signal is generated at time to when the rotation angle of the engine coincides with the reference position, the count value of the ignition timing measurement time Ti that has already been calculated is calculated as the first count value.
Is set in the timer 3c. The first timer 3c is shown in FIG.
The clock pulse P is counted as shown in FIG.
When the counting of the ignition timing measurement time Ti calculated at the time ti is completed (ignition timing), the CPU 3a generates an ignition signal. When the ignition signal is generated, the ignition circuit 11 (see FIG. 4) causes a sudden change in the primary current of the ignition coil 6, so that a high voltage for ignition is generated in the secondary coil of the ignition coil. When a high voltage for ignition is generated, a spark is generated in the spark plug 12, so that ignition noise Sn is generated. If the ignition noise Sn is on the signal line 5, an error occurs in the contents of the program read by the CPU 3a, causing a malfunction, or the control operation cannot be read and the control operation is locked.

Since the period Tn during which the ignition noise occurs is substantially constant, the time ti 'at which the ignition noise disappears is obtained by actual measurement, and the time ti' slightly before the timing ti at which the ignition noise occurs (for example, 2-3). Time before counting) t
The period from 1 to a time t2 slightly after the time ti 'at which the ignition noise disappears (for example, a time after a few counts) t2 is defined as a communication suspension period Tnc. If communication with the memory 4 is stopped, malfunctions due to ignition noise on the signal line 5 can be reliably prevented.

In order to stop the communication between the microprocessor and the external memory during the communication stop period Tnc as described above, for example, the following processing may be performed.

That is, at time to, the first position detection signal Vp1
Occurs, the count value of the ignition timing measurement time Ti is set in the first timer 3c as shown in FIG. 2B, and at the same time, the ignition timing is set in the second timer 3d as shown in FIG. The count value Ti 'for communication stop timing measurement, which is several counts smaller than the count value of the measurement time, is set, and each timer starts counting. When the timer 3d has completed counting the communication stop timing measurement count value Ti 'at a time t1 slightly before the ignition timing, the interrupt controller 3
After prohibiting f from accepting all other interrupts other than the interrupt by the second timer 3d, by executing an instruction for prohibiting communication with the external memory, the communication between the microprocessor 3 and the external memory 4 is performed. In addition to prohibiting the communication, as shown in FIG. 2D, the count value of the communication suspension period Tnc is set in the second timer 3d, and the counting is started. The second timer 3d sets the communication suspension period Tnc at time t2.
When the interruption by the second timer 3d is input when the counting of the above is completed, the prohibition of the communication command is released. In the interrupt processing, normal control is started by accepting all interrupts. Communication suspension period Tnc
Is obtained by actual measurement in advance and stored in the external memory 4. After the microcomputer is started, before the control operation is started, the RA in the microprocessor is determined.
It is read into M3e.

In the above example, the second timer 3d and the step of setting the communication stop timing measurement count value Ti 'in the second timer 3d make the controlled object more likely to generate electrical noise. Communication stop timing detecting means for detecting a slightly earlier time as the communication stop timing is realized.

In the process of setting the count value of the communication stop period Tnc to the second timer 3d at the time t1, a timer set for setting the communication stop time to the timer when the communication stop timing detecting means detects the communication stop timing. Means are realized.

Further, when the second timer 3d has completed counting the communication stop timing measurement count value, the interrupt controller 3f is prohibited from accepting all other interrupts other than the interrupt by the second timer 3d. And the step of permitting the interrupt controller to accept all interrupts when the counting of the count value of the communication suspension period Tnc is completed, so that the communication between the microprocessor and the external memory is performed when the communication suspension timing is detected. Ban,
Communication control means for permitting communication between the microprocessor and the external memory when the timer completes measuring the communication stop time is realized.

In the above example, the communication suspension period Tnc is counted using the timer 3d provided outside the CPU. However, the communication suspension period may be measured by software. FIGS. 3A to 3C are flowcharts showing the algorithm of the software used in this case.

In the case of the algorithm shown in FIG. 3, when the power of the microcomputer is turned on, as shown in FIG. 3A, each part is initialized and interrupt to the external memory is permitted. Thereafter, in step 2, a program for looping a predetermined number of times on the internal RAM 3e of the microprocessor (a loop subroutine in the RAM in FIG. 3C) is read from the external memory 4 and RA is read.
Write to M3e. Next, in step 3, the value of the loop counter is set to 0, and the process proceeds to a main routine (not shown).
In the main routine, calculation of the rotation speed of the internal combustion engine, calculation of ignition timing, fuel injection time, and the like are performed.

When the first position detection signal Vp1 is generated at the first rotation angle position of the engine, a communication stop timing measurement count value Ti 'is set in the second timer 2d, and the count is started. When this counting is completed at time t1, FIG.
At time t1 shown in FIG. In this interrupt processing, all interrupts including the timer are prohibited in step 4 and the internal RAM 3 shown in FIG.
Jump to the inner e loop routine.

In the loop routine in the internal RAM 3e shown in FIG. 3C, first, in step 6, the count value of the loop counter set at a predetermined address of the RAM is set to a set value N.
It is determined whether or not this is the case. As a result, if the count value of the loop counter is smaller than N, the process proceeds to step 7 to perform a process of adding (incrementing) 1 to the value of the loop counter, and returns to step 6. These processes are repeated until the value of the loop counter reaches N (loop in the RAM).
When it is determined that the count has reached the limit, the process proceeds to step 8 and the count value of the loop counter is set to 0. In step 9, the prohibition of accepting all the interrupt commands is released, and the communication between the microprocessor 3 and the external memory is performed. Allow communication to take place.

When the above processing is performed, the RAM 3
CPU3 while looping between steps 6 and 7 in e
Communication between a and the external memory 4 is stopped. By appropriately setting the set value N of the count value of the loop counter,
The communication suspension period Tnc can be set appropriately.

In the case of the algorithm shown in FIG. 3, a loop program for looping a program stored in the internal RAM 3e a certain number of times after the microcomputer is started is stored in the internal RAM 3e in step 2 of FIG. A loop program writing means for writing is realized. Further, the timer 3d counts the count value Ti 'for measuring the communication stop timing, and at time t1, the count value Ti' in FIG.
The process of executing the interrupt routine of (B) implements a communication stop timing detecting unit that detects a time slightly earlier than the timing at which the control target generates electrical noise as the communication stop timing. Further, according to steps 4 and 5 of the interrupt routine of FIG. 3B, when the communication stop timing detecting means detects the communication stop timing t1, the communication between the microprocessor 3 and the external memory 4 is prohibited. Communication stop timing loop processing means for executing the loop program of C) is realized.
Steps 6 to 9 in FIG. 3C implement a communication permitting means for permitting communication between the microprocessor and the external memory when a predetermined number N of loops by the loop program is completed.

In the above description, the case where the communication between the CPU and the external memory is stopped during the period in which the ignition device generates the ignition noise is taken as an example. Similarly, since the timing at which the control target generates noise can be accurately predicted, similarly, communication is stopped during a period from a time slightly before the noise generation timing to a time slightly after the noise disappearing time. By stopping the communication between the CPU 3a and the external memory 4 during that period, a malfunction due to noise can be prevented.

For example, the injector 7 generates noise when the drive current supplied to the solenoid coil 7a is cut off, but the timing at which the drive current of the solenoid coil is cut off is determined by the start of energization to the solenoid coil 7a. And the fuel injection time. The period during which the solenoid coil 7a generates noise may be obtained by actual measurement and stored in an external memory.

In the above example, the timer 3d is used to detect the timing for stopping the communication. However, the timer 3c for measuring the ignition timing and the like is used to determine the timing for stopping the communication based on the count. You may make it detect.

In the above description, the case where the ignition device and the fuel injection device for the internal combustion engine are controlled is taken as an example.
The present invention can be widely applied to a case where a microcomputer is used to control a control target capable of accurately predicting when electrical noise will occur.

[0048]

As described above, according to the present invention, the control operation is interrupted by stopping the communication between the microprocessor and the external memory during the period in which the control target is expected to generate noise. Therefore, it is possible to prevent a malfunction from occurring due to noise on a signal line connecting the CPU and the external memory.

Further, according to the present invention, it is not necessary to devise a circuit pattern on a circuit board or to add a circuit component for lowering the impedance of a signal line. It is possible to prevent the substrate from being enlarged.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration example of a microcomputer used in a control device according to the present invention.

FIG. 2 is a timing chart for explaining a control method according to the present invention.

FIGS. 3A to 3C are flowcharts showing an algorithm of a program used when implementing a control method according to the present invention.

FIG. 4 is a configuration diagram schematically illustrating a configuration example of a control device to which the present invention is applied.

FIG. 5 is a configuration diagram schematically showing a configuration of a main part of a conventional control device in which noise countermeasures are taken.

[Explanation of symbols]

 Reference Signs List 1 control device 2 microcomputer 3 microprocessor 3a CPU 3b interface 3c first timer 3d second timer 3e RAM 3f interrupt controller 4 external memory 5 signal line 6 ignition coil 7 injector 10 relay 11 ignition circuit 13 injector drive circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 11/00 F02D 45/00 F02P 5/15 F02P 15/00 G06F 13/00

Claims (4)

(57) [Claims] At least a CPU, a timer, and an internal RAM
Having interrupt and interrupt controller
And an external memory storing programs and control data.
And a signal line connects between the CPU and the external memory.
Using a microcomputer connected to the
A specific control pair that can predict how long
In the control device for controlling an elephant, a timing at which the controlled object generates electrical noise
Also detects a slightly earlier time as the communication stop timing
A communication stop timing detecting means, and a communication stop timing by the communication stop timing detecting means.
When communication is detected, the communication stop time is set in the timer.
Timer setting means for resetting the microcontroller when the communication stop timing is detected.
Prohibits communication between the processor and the external memory,
When Ima has completed the timing of the communication
Communication system that allows communication between the processor and external memory
And a control means.
Control device using data. 2. At least a CPU, a timer, and an internal RAM
Having interrupt and interrupt controller
And an external memory storing programs and control data.
And a signal line connects between the CPU and the external memory.
Using a microcomputer connected to the
A specific control pair that can predict how long
In a control device for controlling an elephant , a certain number of times after the microcomputer is started
Loop through a program stored in the internal RAM
Loop program for writing a loop program to the internal RAM
Program writing means, and a timing at which the controlled object generates electrical noise.
Also detects a slightly earlier time as the communication stop timing
A communication stop timing detecting means, and a communication stop timing by the communication stop timing detecting means.
The microprocessor and external media when
After prohibiting communication with the
A communication stop timing loop means to be executed, the loop is terminated in a certain number of times by the loop program
Communication between the microprocessor and external memory
Communication permission means for permitting communication.
Control device using a microcomputer. 3. The control target is an ignition device for an internal combustion engine.
The timing at which the electrical noise occurs is determined by the ignition timing.
The microcomputer according to claim 1 or 2, wherein
Control device using 4. The control target is a fuel injection device for an internal combustion engine.
The timing at which the electrical noise occurs is determined by the injector.
To shut off the power to the solenoid coil of the
The microcomputer according to claim 1 or 2, wherein
Control device using