JP6952183B2 - Engine control unit - Google Patents

Description

The present invention relates to an engine control device that controls an engine (internal combustion engine) using a microcomputer.

As an engine control device for controlling an engine ignition device, a fuel injection device, and the like, a device in which various means necessary for control are configured by using a microcomputer is widely used. In this type of control device, information about the engine acquired when the engine is stopped is stored in the memory, and this information is used for engine control when the engine is restarted and for monitoring the presence or absence of an abnormality in the engine. Is being done.

For example, Patent Documents 1 to 3 disclose an engine control device that stores temperature information such as an engine cooling water temperature and an intake air temperature detected when the engine is stopped in a memory. In this way, if the engine temperature information when the engine is stopped is stored in the memory, for example, based on the difference between the stored engine temperature information and the engine temperature information detected when the engine is restarted. , The amount of fuel remaining in the intake passage of the engine can be estimated by estimating the elapsed time from when the engine is stopped to when it is restarted, so the fuel injection amount when the engine is restarted is appropriate. It is possible to improve the startability of the engine by setting the range.

In addition, when the engine is stopped, the engine operating time, load driving time, etc. are applied to the engine for the purpose of collecting useful data when managing the engine maintenance and the maintenance of the load driven by the engine. It is also conceivable to store the related information and / or the related information related to the engine load in the non-volatile memory.

Japanese Unexamined Patent Publication No. 6-229284 Japanese Unexamined Patent Publication No. 2003-254121 Japanese Unexamined Patent Publication No. 2013-204466

In order to ensure that information related to the engine and / or information related to the load of the engine is stored in the memory when the engine is stopped (hereinafter referred to as engine stop processing), the processing is performed when the engine is stopped. It is necessary to keep the microcomputer up and running for the time it takes to complete. When a device (for example, a vehicle) equipped with an engine is provided with a battery, the microcomputer can be kept in an operating state by the voltage of the battery even when the engine is stopped, so that the microcomputer can be engineed without any problem. It is possible to perform processing at the time of stop.

However, in a batteryless engine control device that controls an engine mounted on a device without a battery, a control power supply unit that generates a constant DC voltage using a generator driven by the engine as a power source is used as a microcomputer. If the output voltage of the generator is lost when the engine is stopped, the microcomputer cannot be kept in the operating state, and the processing when the engine is stopped cannot be reliably performed.

In order to solve such a problem, for example, a voltage storage means such as a large-capacity capacitor charged by the rectified output of the generator during operation of the engine is added to the power supply unit of the engine control device to provide the engine. It is conceivable to secure the power supply voltage of the microcomputer by utilizing the energy stored in the voltage storage means even after the voltage is stopped.

However, adding an extra voltage storage means such as a capacitor to the power supply unit of the engine control device is not preferable because the number of parts increases, which leads to an increase in the size of the control device and an increase in cost.

An object of the present invention is for an engine in which a microcomputer can be kept in an operating state even when the engine is stopped without adding an extra voltage storage means such as a capacitor in a battery-less configuration. The purpose is to provide a control device.

The present invention is intended for an engine control device that controls an engine using a microprocessor whose operation is guaranteed when a power supply voltage having a voltage value within a certain operation guarantee range is applied to the power supply terminal. The present specification discloses at least the first to sixth inventions shown below in order to achieve the above object.

<First invention>
In the present invention, as an ignition device for igniting an engine, an ignition capacitor provided on the primary side of an ignition coil and a generator driven by the engine to output an AC voltage are used as a power source, and the ignition capacitor has one polarity. It is equipped with a capacitor charging circuit for charging and a discharge switch provided to discharge the charge accumulated in the ignition capacitor when it is turned on through the primary coil of the ignition coil, and discharges at the ignition timing of the engine. A condenser discharge type ignition device that induces a high voltage for ignition in the secondary coil of the ignition coil by turning on the switch is used.

In the present invention, the control power supply unit that converts the output voltage of the generator into a power supply voltage having a voltage value within the guaranteed operation range and applies it to the power supply line connected to the power supply terminal of the microcomputer, and both ends of the ignition capacitor. A step-down circuit is provided to step down the voltage of the above voltage to a voltage having a voltage value within the guaranteed operation range and apply it to the power supply line. Even after the voltage to be applied falls below the lower limit of the guaranteed operation range, the microcomputer is maintained in the operating state while the voltage applied to the power supply line from the step-down circuit is within the guaranteed operation range.

With the above configuration, even if the device on which the engine is mounted does not have a battery, it is possible to apply a power supply voltage within the guaranteed operating range to the microcomputer from the ignition capacitor through the step-down circuit when the engine is stopped. , It is possible to make the microcomputer surely perform the processing when the engine is stopped. Generally, the ignition capacitor is charged at a high voltage and has a high electrostatic energy. Therefore, when the engine is stopped, the ignition capacitor is applied to the microcomputer through a step-down circuit to perform processing when the engine is stopped. The microcomputer can be kept in operation for the time required for the computer.

In addition, with the above configuration, the power supply voltage can be supplied to the microcomputer when the engine is stopped by using the ignition capacitor provided in the ignition device, which is an essential component for operating the engine. There is no need to add extra components such as capacitors to keep the microcomputer up and running when stopped. Therefore, according to the present invention, there is an advantage that the size of the control device is not increased and the cost is not increased.

<Second invention>
In the second invention, an engine stop determination means for determining whether or not the engine is stopped, and an engine stop determination for prohibiting the step-down operation during operation of the engine and permitting the ignition operation to be performed. After it is determined that the engine is stopped by the means, the ignition operation and the step-down operation management means for managing the ignition operation and the step-down operation so as to prohibit the ignition operation and allow the step-down operation to be performed. The microcomputer is programmed to configure.

<Third invention>
The third invention is applied to the second invention, and in the present invention, a pulse generator that generates a pulse each time the crankshaft of the engine rotates by a set angle is provided. In this case, the engine stop determination means can be configured to determine that the engine will stop when the interval at which the pulse generator generates the pulse exceeds the set interval.

<Fourth invention>
The fourth invention is applied to the third invention. In the present invention, a switch is provided which is operated when the engine is stopped to give an engine stop command to the microcomputer, and this switch is operated. An engine stop determination means is configured so as to determine that the engine will stop even when an engine stop command is given to the microcomputer.

<Fifth invention>
The fifth invention is applied to any one of the first to fourth inventions. In the present invention, a rectified power supply unit is provided that outputs a DC voltage maintained below a set value with the output voltage of the generator as an input, and the capacitor charging circuit boosts the DC voltage output by the rectified power supply unit. It is configured to charge the ignition capacitor with the output voltage of the circuit. In this case, the microcomputer starts the operation of the booster circuit at a timing before the ignition timing of the engine, is later than the timing at which the charging of the ignition capacitor is completed, and is ahead of the ignition timing of the engine. It is programmed to configure a booster circuit control means that controls the booster circuit to stop the operation of the booster circuit.

<Sixth invention>
The sixth invention is applied to any one of the first to fifth inventions, and in the present invention, information related to the engine and / or engine load in the process of shifting the engine from the operating state to the stopped state. The microcomputer is programmed to perform an engine stop process that stores information related to the above in a non-volatile memory.

According to the present invention, even when the device in which the engine is mounted is not provided with a battery, it is possible to apply a power supply voltage within the operation guarantee range to the microcomputer from the ignition capacitor through the step-down circuit when the engine is stopped. It is possible to ensure that the microcomputer performs the processing when the engine is stopped.

Further, according to the present invention, the power supply voltage can be supplied to the microcomputer when the engine is stopped by using the ignition capacitor provided in the ignition device, which is an indispensable component for operating the engine. The advantage is that there is no need to add extra components such as capacitors to keep the microcomputer up and running when stopped, which does not lead to larger controllers or higher costs. can get.

FIG. 1 is a circuit diagram showing a configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing an overall configuration of the embodiment of FIG. 1 by representing a portion that performs a specific function with blocks. FIG. 3 is a flowchart showing an example of an algorithm of a program to be executed by a microcomputer to configure the engine stop determination means and the ignition operation / step-down operation management means shown in FIG.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows an embodiment of the present invention, in which 1 is a generator (ACG) driven by an engine (not shown), and 2 is an angle at which the crank shaft of the engine is set. A pulse generator that generates a pulse each time it rotates, 3 is an ignition coil, and 4 is an ECU (electronic control unit) that constitutes a main part of an engine control device that controls an engine ignition device, a fuel injection device, and the like. For the sake of simplicity, it is assumed that the engine is a single cylinder engine in this embodiment.

The generator 1 includes, for example, a flywheel magnet rotor attached to the crank shaft of an engine and a stator formed by winding a power generation coil around an armature iron core having a magnetic pole portion facing the magnetic poles of the rotor. It consists of a magnetic AC generator and an exciting AC generator (alternator), and outputs AC voltage in synchronization with the rotation of the engine.

The pulse generator 2 may be any one as long as it generates a pulse each time the crank shaft of the engine rotates by a set angle, but in the present embodiment, it constitutes the rotor yoke of the generator 1. The pulse generator 2 is composed of a retractor 1a formed of protrusions provided on the outer periphery of the flywheel and a signal generator that detects the retractor 1a and generates a pulse signal. The signal generating electron constituting the pulse generator 2 includes a signal generating iron core having a magnetic pole portion facing the retractor 1a, a signal coil wound around the iron core, and a permanent magnet magnetically coupled to the iron core. It is fixed to the case of the engine.

The signal generating electrons constituting the pulse generator 2 are generated in the iron core when the retractor 1a starts and ends facing the magnetic pole portion of the signal generating iron core in the process of rotating the rotor of the generator 1. The change in the generated magnetic flux induces a pulse signal having a different polarity in the signal coil. In the present embodiment, only one retractor 1a is provided on the outer periphery of the rotor of the generator 1, and the pulse generator 2 generates positive and negative pulses only once while the crankshaft of the engine makes one rotation. It has become like. In the present embodiment, among the positive and negative pulses generated by the pulse generator 2, the pulse generated when the signal-generating electron starts to face the retractor is set as the first pulse, and the signal-generating electron is opposed to the retractor. The pulse generated at the end is defined as the second pulse. When the rotation angle position of the crankshaft of the engine matches the reference crank angle position set at the crank angle position further advanced than the maximum advance angle position of the ignition position (crank angle position where ignition is performed) of the engine. The pulse generator 2 is provided so that the pulse of 1 is generated and the second pulse is generated at the crank angle position slightly behind the crank angle position when the engine piston reaches top dead center.

The ignition coil 3 has a primary coil 3A and a secondary coil 3B, one end of both coils is grounded, and a high voltage Vh induced in the secondary coil 3B is attached to an engine cylinder (not shown). It is applied to the spark plug PL.

The ECU 4 includes a component of an ignition circuit that constitutes an engine ignition device together with an ignition coil 3, a component such as a microcomputer used for controlling an engine ignition timing, a fuel injection timing, and the like, as well as an ignition device and a microcomputer. The components of the power supply unit that give the necessary power supply voltage to the engine are provided.

Of the components of the ECU 4 shown in FIG. 1, 5 is an ignition capacitor provided on the primary side of the ignition coil 3 and charged to one polarity using the generator 1 as a power source, and 6 is turned on. It is a thyristor constituting a discharge switch that discharges the electric charge accumulated in the ignition capacitor 5 through the primary coil 3A of the ignition coil. One end of the ignition capacitor 5 is connected to the cathode of the diode 7 to which the anode is connected to the non-grounded end of the primary coil 3A of the ignition coil 3, and the connection point between one end of the ignition capacitor 5 and the diode 7 A diode 8 that allows a charging current to flow when the ignition capacitor 5 is charged is connected between the grounds with its cathode facing the ground side.

The thyristor 6 constituting the discharge switch is connected between the other end of the ignition capacitor 5 and the ground with its cathode facing the ground side. Reference numeral 9 denotes a booster circuit that boosts the DC voltage VB supplied from the generator 1 through the rectifying power supply unit 10, and its positive output terminal is connected to the other end of the ignition capacitor 5. The negative output terminal of the booster circuit 9 is grounded, and the rectifying power supply unit 10, the booster circuit 9, and the diode 8 form a capacitor charging circuit that charges the ignition capacitor 5 to one polarity using the generator 1 as a power source. Has been done.

The booster circuit 9 has a control terminal 9a, which is connected to port P1 of the microcomputer 11. The booster circuit 9 performs a boosting operation when a high-level permission signal is given from the port P1 of the microcomputer 11 to the control terminal 9a, and the signal given from the port P1 of the microcomputer 11 to the control terminal 9a is at zero level. It is configured to stop the boosting operation when it is set to (when a prohibition signal is given). As the booster circuit 9, a commercially available booster switching regulator or a DC-DC converter can be used.

Further, the port P2 of the microcomputer 11 is connected to the gate of the thyristor 6, and when the ignition signal Si is output from the port P2, the thyristor 6 is turned on and the charge accumulated in the ignition capacitor 5 is used for ignition. The capacitor 5 → the thyristor 6 → the primary coil 3A of the ignition coil 3 → the diode 7 → the ignition capacitor 5 is discharged through a closed circuit.

In the present embodiment, the ignition coil 3, the ignition capacitor 5, the thyristor 6, the diodes 7 and 8, and the booster circuit 9 constitute a capacitor discharge type ignition device. The basic operation of this ignition device is as follows.

The operation of the booster circuit 9 is permitted at a timing predetermined time before the ignition timing of the engine, the booster circuit 9 is put into the operating state, the booster circuit 9 → the ignition capacitor 5 → the diode 8 → the closed circuit of the booster circuit 9. The ignition capacitor 5 is charged to the indicated polarity through a capacitor charging circuit comprising the same.

After the boosting operation of the booster circuit 9 is prohibited at a timing that is later than the timing when the charging of the ignition capacitor 5 is completed and earlier than the ignition timing of the engine, the gate of the thyristor 6 is connected to the port P2 of the microcomputer 11 at the ignition timing. Is given the ignition signal Si. As a result, the thyristor 6 becomes conductive, so that the electric charge accumulated in the ignition capacitor 5 is discharged through the thyristor 6, the primary coil 3A of the ignition coil, and the diode 7. This discharge induces a high voltage in the primary coil 3A of the ignition coil 3, and this voltage is further boosted by the boost ratio between the primary and secondary of the ignition coil. Therefore, a high voltage for ignition is generated in the secondary coil 3B of the ignition coil. Vh induces. Since this high voltage is applied to the spark plug PL attached to the cylinder of the engine, spark discharge occurs in the spark plug PL and the engine is ignited.

After the ignition operation is completed, the operation of the booster circuit 9 is permitted again, and the ignition capacitor 5 is charged. By repeating these operations, the engine is ignited at a predetermined ignition timing, and the engine is kept in an operating state.

In order to give the rotation information of the engine to the microcomputer 11, the first pulse and the second pulse generated when the pulse generator 2 detects the front end side edge and the rear end side edge in the rotation direction of the retractor 1a, respectively, are generated. A rotation detection circuit 14 is provided which shapes the waveform and outputs the first rotation detection pulse Vp1 and the second rotation detection pulse Vp2, and these rotation detection pulses are input to ports P3 and P4 of the computer 11 respectively. There is. Of the first rotation detection pulse Vp1 and the second rotation detection pulse Vp2, the first rotation detection pulse Vp1 whose phase is advanced is set to a position whose phase is advanced from the maximum advance position of the ignition position. It occurs at the reference crank angle position, and the second rotation detection pulse Vp2 is generated at a position slightly later than the crank angle position where the engine piston reaches the top dead point.

The microcomputer 11 calculates the ignition timing of the engine with respect to the rotation speed of the engine obtained from the generation interval of the first rotation detection pulse or the second rotation detection pulse given from the rotation detection circuit 14, and the calculated ignition timing. Is detected, an ignition signal is given to the thyristor 6 to perform an ignition operation.

The rectifier power supply unit 10 that generates the DC voltage VB input to the booster circuit 9 is a rectifier circuit that rectifies the AC voltage output by the generator 1 and a control that controls the output of this rectifier circuit to be limited to the set voltage or less. It consists of a first regulator (REG) 10A equipped with a circuit and a capacitor 10B for smoothing the output voltage of the first regulator 10A, and the output voltage VB of the rectified power supply unit 10 obtained at both ends of the capacitor 10B is a booster circuit. It is entered in 9.

The microcomputer 11 includes a CPU, a storage device including a ROM (read-only memory) and a RAM (random access memory), and when the power supply voltage Vc given to the power supply terminal is within a predetermined operation guarantee range. By holding the operating state and executing the program stored in the ROM, a means for performing various functions is configured.

In order to obtain the power supply voltage given to the microcomputer 11, a control power supply unit 12 for converting the output voltage of the rectified power supply unit 10 into the rated power supply voltage (for example, 5 volts) of the microcomputer 11 is provided. The control power supply unit 12 is composed of a second regulator 12A that converts the output voltage of the rectified power supply unit 10 into a voltage suitable for the rated power supply voltage of the microcomputer 11, and an output capacitor 12B to which the output voltage of this regulator is applied. The voltage Vc obtained at both ends of the output capacitor 12B is applied to the power supply line connected to the power supply terminal of the computer 11.

A non-volatile memory (EEPROM) 13 is connected to the microcomputer 11 in order to store information about the engine and / or information about the load of the engine acquired in the processing when the engine is stopped.

Further, in the present embodiment, the stop switch 15 operated when the engine is intentionally stopped is connected between the port P5 of the microcomputer 11 and the ground, and the stop switch 15 is operated to stop the engine in the on state. When this is done, an engine stop command is given to the microcomputer 11. The stop switch 15 may be a switch that is operated exclusively when the engine is stopped, or may be composed of a key switch.

Further, even after it is determined that the engine is stopped, the voltage across the ignition capacitor 5 is micro-sized in order to keep the microcomputer 11 in the operating state for the time required to complete the process when the engine is stopped. A step-down circuit 16 is provided which steps down the voltage to a DC voltage Vc having a voltage value within the operation guarantee range of the power supply voltage of the computer 11 and applies it to the power supply line of the microcomputer.

The step-down circuit 16 has a control terminal 16a, an input terminal 16b, and a ground terminal 16c. The control terminal 16a is connected to the port P6 of the microcomputer 11, and the voltage across the ignition capacitor 5 is the ignition coil 3. It is input between the input terminal 16b and the ground terminal 16c of the step-down circuit 16 through the primary coil 3A and the diode 7. The step-down circuit 16 is the voltage across the ignition capacitor input through the primary coil of the ignition coil 3 and the diode 7 when a high level permission signal is given from the port P6 of the microcomputer 11 to the control terminal 16a. Is stepped down to a voltage having a voltage value within the operation guarantee range of the power supply voltage of the microcomputer 11, and applied to the power supply line of the microcomputer 11. The step-down circuit 16 also stops operating when the signal given to the control terminal 16a from the port P6 of the microcomputer is set to zero level (when a prohibition signal is given).

As the step-down circuit 16 that steps down the DC voltage across the ignition capacitor 5, for example, a commercially available step-down switching regulator that steps down the input voltage by turning on and off a switching element such as a power MOSFET can be used. As the step-down switching regulator, a small type (chip type) that can be easily mounted in the ECU can be easily obtained.

With the above configuration, even if the device on which the engine is mounted does not have a battery, the power supply voltage that falls within the guaranteed operating range from the ignition capacitor 5 to the power supply terminal of the microcomputer 11 through the step-down circuit 16 when the engine is stopped. Therefore, it is possible to ensure that the microcomputer performs the processing when the engine is stopped. Since the ignition capacitor 5 is charged at a high voltage and has high electrostatic energy, the engine stop processing is performed by applying a power supply voltage from the ignition capacitor to the microcomputer 11 through the step-down circuit 16 when the engine is stopped. The microcomputer can be kept up and running for the time required to do so.

Further, with the above configuration, the power supply voltage can be supplied to the microcomputer 11 when the engine is stopped by using the ignition capacitor 5 provided in the ignition device, which is an indispensable component for operating the engine. It is not necessary to add extra parts such as capacitors to keep the microcomputer in operation when the engine is stopped, which prevents the control device from becoming large and costly. Can be done.

In the example shown in FIG. 1, the components of the circuit that constitutes the ignition device together with the ignition coil 3, such as the ignition capacitor 5, the thyristor 6, and the diodes 7 and 8, are provided in the ECU 4, but all of these components or A part can be provided outside the ECU. Further, in the example shown in FIG. 1, the rectifying power supply unit 10 and the control power supply unit 12 are provided inside the ECU 4, but these power supply units can also be provided outside the ECU.

In the engine control device of the present embodiment, various function realization means necessary for controlling the engine are configured by causing the microcomputer 11 to execute a predetermined program. With reference to FIG. 2, the overall configuration of the embodiment of FIG. 1 including the functional realization means configured by the microcomputer is shown in a block diagram. In FIG. 2, the same parts as those shown in FIG. 1 are designated by the same reference numerals.

In the present embodiment, the ignition control unit 20, the booster circuit control means 21, the engine stop determination means 22, and the ignition operation / step-down operation management means 23 are configured by causing the microcomputer 11 to execute a predetermined program. do.

The ignition control unit 20 is a part that controls the ignition timing of the engine, and its basic configuration is the same as that conventionally used. The ignition control unit 20 has, for example, a rotation speed calculation means that calculates the rotation speed of the engine from the generation interval of the rotation detection pulse Vp1 given through the rotation detection circuit 14, and a rotation speed calculated by the rotation speed calculation means. It can be composed of an ignition timing calculating means for calculating the ignition timing of the engine and an ignition signal generating means for generating an ignition signal Si to be given to the thyristor 6 when the calculated ignition timing is detected.

The ignition timing of the engine is, for example, the time required for the crankshaft to rotate in the section from the reference crank angle position, which is the crank angle position where the first rotation detection pulse Vp1 is generated, to the crank angle position where the ignition operation is performed. Calculated in form. The microcomputer 11 starts the measurement of the ignition timing calculated when the first rotation detection pulse Vp1 is generated (when the reference crank angle position is detected), and when the measurement is completed, the thyristor 6 from the port P2 The ignition signal Si is supplied to the gate to perform the ignition operation.

The booster circuit control means 21 only charges the ignition capacitor 5 in order to prevent the thyristor 6 from being unable to turn off due to a voltage applied from the booster circuit 9 to the thyristor 6 during the ignition operation. This is a means for controlling the booster circuit 9 so as to stop the booster operation when the booster circuit 9 is operated and the thyristor 6 is turned on to perform the ignition operation. The booster circuit control means 21 gives a permission signal to the control terminal 9a of the booster circuit 9 at a booster operation start timing set at a timing later than the ignition timing of the engine to start the operation, and the booster circuit control means 21 boosts the booster circuit 9. It can be configured to give a prohibition signal to the booster circuit to stop its operation at a timing later than the start timing and earlier than the ignition timing of the engine.

The engine stop determination means 22 is means for determining that the engine is about to shift from the operating state to the stopped state from the generation interval of one rotation detection pulse generated by the rotation detection circuit 14, and in the present embodiment, this determination means. However, it is configured to determine that the engine stops when the generation interval of the rotation detection pulse Vp1 (the time required for one rotation of the crankshaft) exceeds the stop determination value. It is also preferable that the engine stop determination means 22 is configured to determine that the engine will stop even when the stop switch 15 is operated and an engine stop command is given to the microcomputer.

The ignition operation / step-down operation management means 23 prevents the step-down operation from being performed at the same time as the ignition operation from interfering with the ignition operation, and lowers the voltage across the ignition capacitor 5 to supply power to the microcomputer. It is a means for managing the ignition operation and the step-down operation in order to prevent the ignition capacitor from being discharged through the thyristor 6 when the voltage is supplied. The ignition operation / step-down operation management means 23 used in the present embodiment prohibits the step-down circuit 16 from performing the step-down operation during engine operation and permits the ignition device to perform the ignition operation (the ignition signal Si is sent to the thyristor 6). After it is determined by the engine stop determination means 22 that the engine is stopped, the ignition operation and the step-down operation are performed so as to prohibit the ignition operation and allow the step-down operation to be performed. to manage.

Referring to FIG. 3, a flowchart showing a task processing algorithm that causes the microcomputer 11 to repeatedly execute the step-up circuit control means 21, the engine stop determination means 22, and the ignition operation / step-down operation management means 23 at minute time intervals. It is shown.

When the process shown in FIG. 3 is started, in step S101, the count value EnstCount of the engine stall counter, which is a counter that counts the number of times the task process of FIG. 3 is executed during one rotation of the crankshaft of the engine, is incremented. do. The count value of the engine stall counter is cleared by the interrupt process executed when the rotation detection circuit 14 generates one rotation detection pulse Vp1. Next, in step S102, it is determined whether or not the count value EnstCount of the engine stall counter is equal to or greater than the engine stall determination value (determination value for determining whether or not the engine stalls) ENST JUDGE TIME.

While the engine is running, the time required for one rotation of the crank shaft (the interval at which the rotation detection pulse Vp1 is generated) is sufficiently short, and the engine stall counter is cleared before the count value EnstCount reaches the engine stall judgment value ENST JUDGE TIME. Therefore, the count value EnstCount never reaches the engine stall judgment value ENSTJUDGETIME. However, when the engine is stopped, the time required for the crank shaft to make one rotation becomes longer, and the stall counter count value EnstCount becomes equal to or greater than the engine stall judgment value ENSTJUDGETIME. Therefore, the engine stall counter count value EnstCount is the judgment value. By determining whether or not it is EnstCount or higher, it is possible to determine whether or not the engine stops.

When it is determined in step S102 that the count value EnstCount of the engine stall counter is not equal to or greater than the engine stall determination value ENSTJUDGETIME, the ignition device is allowed to perform the ignition operation in step S103, and the step-down circuit 16 performs the step-down operation. Prohibit and end this process.

When it is determined in step S102 that the count value EnstCount of the engine stall counter is equal to or greater than the engine stall determination value ENSTJUDGETIME, the process proceeds to step S104 to make an engine stop determination (determination that the engine will stop soon), and then proceeds to step S105. In step S105, the operation of the step-up circuit 9 is prohibited, the ignition operation is prohibited, and at the same time, the operation of the step-down circuit 16 is permitted, and the supply of the power supply voltage from the step-down circuit 16 to the microcomputer 11 is started.

In the case of the algorithm shown in FIG. 3, the engine stop determination means 22 is configured by steps S101, S102 and S104, and the ignition operation / step-down operation management means 23 is configured by steps S103 and S105. The booster circuit control means 21 permits the control terminal 9a of the booster circuit 9 at a booster operation start timing set at a timing later than the ignition timing of the engine in the task process executed to realize the ignition control unit 20. A step of giving a signal to start the operation and a step of giving a prohibition signal to the booster circuit to stop the operation at a timing later than the start timing of the booster operation of the booster circuit 9 and ahead of the ignition timing of the engine. It can be realized by letting it do.

In the example shown in FIG. 3, it is determined whether or not the engine is stopped based on the rotation speed of the engine. However, if the engine is configured in this way, the engine can be stopped due to a cause such as insufficient torque. Even in this case, it is possible to make the determination that the engine is stopped and keep the microcomputer in the operating state.

When the stop switch 15 is provided as in the embodiment shown in FIGS. 1 and 2, the task of FIG. 3 is to determine that the engine will stop even when the stop switch is operated. It is preferable to configure the process.

With the above configuration, the energy stored in the ignition capacitor can be effectively used when the engine is stopped to supply the power supply voltage to the microcomputer. Therefore, a battery is provided in the device in which the engine is mounted. Even if this is not the case, keep the microcomputer in operation for a certain period of time when the step-down circuit outputs a voltage that has a voltage value that falls within the voltage range in which the operation of the microcomputer is guaranteed when the engine is stopped. Can be done. If the ignition capacitor has a sufficiently large capacitance, it is possible to keep the microcomputer in an operating state for a certain period of time even after the engine is stopped.

As described above, according to the present invention, when an engine control device that controls an engine using a microcomputer has a battery-less configuration, the microcomputer is reliably kept in an operating state for a certain period of time when the engine is stopped. Therefore, it is possible to ensure that the processing performed when the engine is stopped is performed. Also, depending on the capacity of the ignition capacitor, the microcomputer can be kept in operation for a considerably long time after the engine is stopped, so the engine is restarted shortly after the engine is stopped. In this case, the engine starting operation can be started while the microcomputer is operating, and the engine starting can be facilitated. In addition, it is not necessary to add extra parts such as capacitors to keep the microcomputer in operation when the engine is stopped, which prevents the control device from becoming larger and the cost from increasing. Can be done.

In the above embodiment, a capacitor discharge type in which a capacitor charging circuit is configured so as to charge the ignition capacitor 5 with the output voltage of the booster circuit 9 that boosts the DC voltage VB supplied from the generator 1 through the rectifying power supply unit 10. However, the capacitor charging circuit provided in the ignition device that ignites the engine to which the present invention is applied uses a generator that is driven by the engine and outputs an AC voltage as a power source, and the ignition capacitor has one polarity. It is not limited to the one used in the above embodiment as long as it is configured to be charged. For example, an ignition capacitor is installed with a half-wave output voltage of one polarity of an exciter coil that is installed in a generator driven by an engine with a sufficient number of turns and generates an AC voltage in synchronization with the rotation of the engine. It goes without saying that the present invention can also be applied to the case of using a well-known capacitor discharge type ignition device provided with a capacitor charging circuit of a type that charges to the polarity of.

In the above embodiment, an engine control device whose control target is the engine ignition device is taken as an example. However, in addition to the control of the ignition device, the control of the fuel injection amount of the fuel injection device and the control of the idling speed of the engine are taken. Of course, the present invention can also be applied to an engine control device that also performs the above.

Further, in the above embodiment, the engine to be controlled is a single-cylinder engine, but it goes without saying that the present invention can be applied to an engine control device that controls a multi-cylinder engine.

1 Generator 2 Pulse generator 3 Ignition coil 4 ECU
5 Ignition capacitor 6 Thyristor (discharge switch)
7 Diode 8 Diode 9 Booster circuit 10 Rectifier power supply 11 Microcomputer 12 Control power supply 13 EEPROM
14 Rotation detector 15 Stop switch 16 Booster circuit 21 Booster circuit control means 22 Engine stop determination means 23 Ignition operation / step-down operation management means

Claims (6)

An engine control device that controls an engine using a microprocessor whose operation is guaranteed when a power supply voltage having a voltage value within a certain operation guarantee range is applied to the power supply terminal.
The ignition device for igniting the engine uses an ignition capacitor provided on the primary side of the ignition coil and a generator driven by the engine to output an AC voltage as a power source to charge the ignition capacitor to one polarity. A capacitor charging circuit and a discharge switch provided so as to discharge the charge accumulated in the ignition capacitor when it is turned on through the primary coil of the ignition coil are provided at the ignition timing of the engine. It comprises a condenser discharge type ignition device that induces a high voltage for ignition in the secondary coil of the ignition coil by turning on the discharge switch to perform an ignition operation.
The voltage across the control power supply unit and the ignition capacitor, which converts the output voltage of the generator into a power supply voltage having a voltage value within the operation guarantee range and applies it to the power supply line connected to the power supply terminal of the microcomputer. Is provided with a step-down circuit that steps down the voltage to a voltage having a voltage value within the guaranteed operation range and applies the step-down operation to the power supply line.
Even after the voltage applied from the control power supply unit to the power supply line falls below the lower limit of the operation guarantee range in the process of shifting from the operating state to the stopped state of the engine, the voltage is applied to the power supply line from the step-down circuit. An engine control device configured to keep the microcomputer in an operating state while the voltage to be generated is within the guaranteed operating range. The microcomputer permits the engine stop determination means for determining whether or not the engine is stopped, and the ignition operation by prohibiting the step-down operation from being performed during the operation of the engine. An ignition operation that manages the ignition operation and the step-down operation so as to prohibit the ignition operation from being performed and allow the step-down operation to be performed after the engine stop determination means determines that the engine is stopped. The engine control device according to claim 1, which is programmed to constitute a step-down operation management means. A pulse generator is provided to generate a pulse each time the crankshaft of the engine rotates a set angle.
The engine stop determination means according to claim 2, wherein the engine stop determination means is configured to determine that the engine stops when the interval at which the pulse generator generates a pulse exceeds a set interval. Control device. A switch that is operated when the engine is stopped and gives an engine stop command to the microcomputer is provided.
The engine control device according to claim 3, wherein the engine stop determination means is configured to determine that the engine is stopped even when the engine stop command is given. A rectifying power supply unit is provided that outputs a DC voltage maintained below a set value by using the output voltage of the generator as an input.
The capacitor charging circuit is configured to charge the ignition capacitor with the output voltage of the booster circuit that boosts the DC voltage output by the rectifying power supply unit.
The microcomputer starts the operation of the booster circuit at a timing before the ignition timing of the engine, is later than the timing at which charging of the ignition capacitor is completed, and is at a timing ahead of the ignition timing of the engine. The engine control device according to claim 1, 2, 3 or 4, wherein the booster circuit control means for controlling the booster circuit is programmed to stop the operation of the booster circuit. The microcomputer is programmed to perform engine stop processing for storing information related to the engine and / or information related to the load of the engine in a non-volatile memory in the process of shifting the engine from the operating state to the stopped state. The engine control device according to any one of claims 1 to 5.

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