JP2019011771A - Ignition system of internal combustion engine - Google Patents

Abstract

To solve a problem that a discharge frequency increases in a region where an engine speed is high, and thus output reduction of a coil or thermal destruction of a switch element occurs.SOLUTION: An ignition system of an internal combustion engine comprises: a plurality of coil parts configured to supply output voltage to a common ignition plug; an engine control unit configured to output a first ignition signal and a second ignition signal based on an engine speed; and a thermistor configured to output a detection signal associated with a temperature of the coil parts. When a detection signal associated with a certain coil part among the coil parts reaches a threshold, the first ignition signal supplied at a high engine speed of 4000 rpm functions to stop the certain coil part and drive another coil part different from the certain coil part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ignition coil for igniting an air-fuel mixture of an internal combustion engine, and more particularly to an ignition system including a plurality of ignition coils for one cylinder.

  Conventionally, internal combustion engines have been actively developed to reduce fuel consumption in order to solve environmental damage problems caused by air pollution and fossil fuel depletion, and low fuel consumption is achieved by lean combustion using a mixture with a high air-fuel ratio. Has been realized. However, in such lean combustion, the ignitability of the air-fuel mixture due to the discharge from the spark plug deteriorates. Therefore, the ignitability of the air-fuel mixture can be achieved by increasing the discharge time by performing multiple discharges for one combustion. There are multiple discharge type ignition devices that improve the above. In a multiple discharge type ignition device, it is known that multiple discharge is executed only in a low rotation region in order to suppress temperature rise of the ignition device and electrode wear of the spark plug. For example, Japanese Patent Application Laid-Open No. 11-148452 (hereinafter “ Patent Document 1 ") has been proposed.

  In Patent Document 1, an ignition plug attached to an in-cylinder injection gasoline engine, an ignition coil that generates a spark discharge by applying a high voltage to the ignition plug at an ignition timing, and a primary current of the ignition coil is turned on / off. In an in-cylinder injection gasoline engine ignition device comprising a switching element that performs and an ignition control means that controls on / off operation of the switching element, the ignition control means causes the switching element to be turned off at an ignition timing. The ignition device is described in which the switching element is repeatedly turned on / off later to cause multiple discharge of the spark plug, and the multiple discharge is executed only in a region where the engine speed is low.

Japanese Patent Application Laid-Open No. 11-148452

  However, the conventional ignition device has the following problems. That is, in the ignition device of Patent Document 1, each stroke time in the high rotation region is shortened, and the discharge time ensures good ignitability without performing multiple discharge. Therefore, multiple discharge is executed only in the low rotation region. It is thought that this can suppress the temperature rise of the ignition device in the high rotation region and suppress electrode wear of the spark plug. Since the number of strokes of the internal combustion engine increases between 1000 and 6000, it can be seen that the number of strokes per unit time is 6 times that of 1000 when the number of strokes per unit time is 6000. In this case, the number of discharges is increased without performing multiple discharges in a high rotation region, so that the amount of heat generated by the ignition device is increased.

  The present invention has been made in view of the above problems, and in an ignition device that performs multiple discharge in which the number of discharges is increased as compared with an ignition device that performs single discharge, by suppressing an increase in the temperature of the ignition device, output reduction and thermal destruction can be prevented. It is an object to provide an ignition system for an internal combustion engine that prevents generation.

  In order to solve the above-described problems, the invention of claim 1 of the present invention includes a plurality of coil portions that supply an output voltage to a common spark plug, and a plurality of igniters that individually drive each of the plurality of coil portions. An engine control unit that provides an ignition signal to each of the plurality of igniters, and outputs detection signals relating to either the temperature of the coil unit itself or the ambient temperature of the coil unit provided corresponding to the plurality of coil units And a temperature detection unit configured to supply a first ignition signal for driving a limited coil unit selected based on the detection signal among the plurality of coil units. An ignition system for an internal combustion engine.

  Further, in the first aspect of the invention, the first ignition signal may be configured to stop the certain coil unit when the detection signal related to a certain coil unit among the plurality of coil units reaches a threshold value and is different from this. It is good also as a structure which drives this coil part. Furthermore, the engine control unit may be configured to supply the first ignition signal and a second ignition signal for driving the plurality of coil portions with a predetermined drive pattern.

  The second ignition signal may be configured to alternately drive a certain coil portion and the other coil portion among the plurality of coil portions. Further, the first ignition signal is supplied in a region where the rotational speed of the internal combustion engine is equal to or higher than a predetermined set rotational speed, and the second ignition signal is a region where the rotational speed of the internal combustion engine is less than the predetermined set rotational speed. The predetermined set rotational speed may be approximately 4000 revolutions.

  As described above, a plurality of coil units that supply an output voltage to a common ignition plug, a plurality of igniters that individually drive each of the plurality of coil units, and an ignition signal to each of the plurality of igniters An engine control unit; and a temperature detection unit that is provided corresponding to each of the plurality of coil units and outputs a detection signal related to either the temperature of the coil unit itself or the ambient temperature of the coil unit, and the engine control unit Supplies a first ignition signal for stopping a certain coil unit and driving another coil unit different from this when the detection signal related to a certain coil unit among the plurality of coil units reaches a threshold value. Thus, it is possible to realize an ignition system for an internal combustion engine that suppresses the temperature increase of the ignition device and prevents the output from being reduced or causing thermal destruction.

1 is a block diagram showing an ignition system for an internal combustion engine according to an embodiment of the present invention. (A) is a figure which shows notionally the map which sets the area | region which performs the multiple ignition with respect to engine speed, (b) is a time chart which shows 1 cycle per unit time with respect to engine speed Time chart showing relationship between primary current and secondary current with respect to first ignition signal Time chart showing the relationship between primary current and secondary current for the second ignition signal Flow chart showing operation process of ignition system for internal combustion engine Time chart showing temperature change of coil portion related to ignition system for internal combustion engine

  An example showing the embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a block diagram showing an ignition system for an internal combustion engine according to an embodiment of the present invention, (a) a diagram conceptually showing a map for setting a region for performing multiple ignition with respect to engine speed, and (b). FIG. 2 is a time chart showing one cycle per unit time with respect to the engine speed, FIG. 3 is a time chart showing the relationship between the primary current and the secondary current with respect to the first ignition signal, and the primary with respect to the second ignition signal. FIG. 4 is a time chart showing the relationship between the current and the secondary current, FIG. 5 is a flowchart showing the operation process of the ignition system for the internal combustion engine, and FIG. 5 is a time showing the temperature change of the coil portion related to the ignition system for the internal combustion engine. The chart is shown in FIG.

  In FIG. 1, an ignition system for an internal combustion engine is composed of an ignition device that outputs a high voltage to an ignition plug 100 provided separately for each cylinder of the engine, and between the electrodes of the ignition plug 100. The air-fuel mixture in the cylinder is ignited by spark discharge generated in the cylinder. The spark plug 100 connects the first coil portion 10 and the second coil portion 20 in parallel. The first coil portion 10 and the second coil portion 20 are configured by electromagnetically coupling the primary coils 12 and 22, the secondary coils 14 and 24, and the iron cores 16 and 26, respectively. Each of the secondary coils 14 and 24 supplies the same output voltage to the common spark plug 100. Further, the first coil unit 10 and the second coil unit 20 are provided with rectifying elements 90a and 90b for preventing secondary currents output from the respective coil units from flowing into the coil units.

  The first coil unit 10 and the second coil unit 20 are connected to a first igniter 30 and a second igniter 40 that drive each of them individually. The first igniter 30 and the second igniter 40 are composed of switch elements 32 and 42 made of IGBTs (insulated gate bipolar transistors) and driver circuits 34 and 44 for supplying current to the switch elements.

  The ignition system for the internal combustion engine includes an engine control unit 50, a power supply device 80, and a DC-DC converter 82. The engine control unit 50 is a microcontroller that performs overall electronic control in the operation of the engine, and the power supply device 80 is a car battery that drives an in-vehicle electrical device of an automobile. Further, the ignition system for the internal combustion engine outputs a detection signal related to the internal temperature of each of the first coil unit 10, the second coil unit 20, the first igniter 30, and the second igniter 40. Thermistors 60a, 60b, 70a, and 70b are provided as temperature detection units.

  Next, the circuit configuration of the ignition system for the internal combustion engine will be described. The DC-DC converter 82 is connected to the low pressure side of each of the primary coils 12 and 22. The primary coils 12 and 22 have a low voltage side connected to the secondary coils 14 and 24 and a high voltage side connected to the collectors of the switch elements 32 and 42. Further, the high voltage side of each of the secondary coils 14 and 24 is coupled via the respective rectifying elements 90a and 90b and connected to the spark plug 100.

  The engine control unit 50 is connected to the driver circuits 34 and 44. The driver circuits 34 and 44 are connected to the gates of the switch elements 32 and 34 and the power supply device 80, respectively. Further, the engine control unit 50 is connected to the thermistors 60a, 60b, 70a, 70b. In addition, the thermistors 60a and 60b are disposed close to the primary coils 12 and 22, and the thermistors 70a and 70b are disposed close to the switch elements 32 and 42, respectively. preferable.

  When an ignition signal is supplied from the engine control unit 50 to each of the first igniter 30 and the second igniter 40, each of the driver circuits 34, 44 receives the ignition signal and receives each of the switch elements 32. , 42 is supplied with current from the power supply device 80. When a current is supplied to each of the switch elements 32 and 42, a primary current flows through each of the primary coils 12 and 22, and the current supplied to each of the switch elements 32 and 42 is cut off. Then, a secondary current flows due to the back electromotive force generated in each of the secondary coils 14 and 24.

  Next, referring to FIG. 2A, an operation map of the ignition system for the internal combustion engine with respect to fluctuations in the engine speed will be described. The engine control unit 50 switches the ignition signal to be supplied to the first igniter 30 and the second igniter 40 with the engine speed of 4000 rpm being a predetermined set speed. That is, the engine control unit 50 supplies a first ignition signal for performing single ignition when the engine speed is 4000 or more, and supplies a second ignition signal for performing multiple ignition when the engine speed is less than 4000. doing. The necessity for multiple ignition will be described with reference to FIG. Since the engine rotates at a higher speed (rotational speed) per unit time in proportion to the increase in the rotational speed, the time required for one rotation differs between 6000 and 1000 rotations. Then, when the engine is running at a low speed, the time required for one rotation becomes longer. Therefore, it is necessary to increase the ignitability with respect to the air-fuel mixture in the engine by increasing the discharge time. Yes.

  However, since the time required for one rotation is shortened when the engine is rotating at high speed, single ignition is performed because sufficient ignitability can be secured for the air-fuel mixture in the engine even by single ignition. However, when the engine speed is 6000 rpm and 1000 rpm, the number of combustion strokes per unit time is 6 times that of the engine of 6000 rpm, and based on this, at a high speed where the engine is 4000 rpm or more, Even in the case of single ignition, the number of secondary current discharges by the first coil unit 10 or the second coil unit 20 increases.

  Accordingly, the first coil portion 10 and the second coil portion 20 generate heat due to an increase in the number of discharges as the engine speed increases. Returning to FIG. 2A, in the ignition system for the internal combustion engine, the transformers such as the primary coils 12 and 14 and the semiconductor elements such as the switch elements 32 and 42 are heated. It shows that the output of the secondary current also decreases.

  Next, FIG. 3 illustrates a time chart in the internal combustion engine ignition system at the time of single ignition execution. The engine control unit 50 supplies a first ignition signal to the first igniter 30 and the second igniter 40 when the engine is rotating at a high speed of 4000 revolutions or more. The first ignition signal is a signal for driving either the first igniter 30 or the second igniter 40. In other words, during the drive period of the first coil unit 10, the primary current flows through the primary coil 12 by turning on the ignition signal to the first igniter 30, and the ignition to the first igniter 30 is performed. When the signal is turned OFF, the primary current flowing through the primary coil 12 is cut off, and a counter electromotive force is generated in the secondary coil 14 so that a secondary current flows. This operation is performed once for each combustion stroke of the engine.

  Similarly, during the driving period of the second coil unit 20, a primary current flows through the primary coil 22 by turning on an ignition signal to the second igniter 40, and the second igniter 40 is turned on. Is turned off, the primary current flowing through the primary coil 22 is cut off, and a back electromotive force is generated in the secondary coil 24, causing a secondary current to flow.

  Next, FIG. 4 illustrates a time chart in the ignition system for the internal combustion engine when multiple ignition is executed. The engine control unit 50 supplies a second ignition signal to the first igniter 30 and the second igniter 40 when the engine is running at a low speed of less than 4000 revolutions. The second ignition signal is a signal for alternately driving the first igniter 30 and the second igniter 40. That is, when the engine control unit 50 turns on the ignition signal to the first igniter 30 and turns off the ignition signal to the second igniter 40, a primary current flows through the primary coil 12. Further, when the ignition signal to the first igniter 30 is turned off and the ignition signal to the second igniter 40 is turned on, the primary current flowing through the primary coil 12 is cut off and reversely applied to the secondary coil 14. An electromotive force is generated, a secondary current flows, and a primary current flows through the primary coil 22.

  When the ignition signal to the first igniter 30 is turned ON again and the ignition signal to the second igniter 40 is turned OFF again, a primary current flows through the primary coil 12 and flows through the primary coil 22. The primary current is cut off, a back electromotive force is generated in the secondary coil 24, and a secondary current flows. As a result, the secondary current output from each of the secondary coils 14 and 24 is alternately output to the spark plug 100 to maintain a secondary current having a long discharge time.

  Next, referring to FIG. 5, the operation process of the ignition system for the internal combustion engine will be described. The engine control unit 50 detects the engine speed (S1), and determines whether the engine speed detected in S1 is 4000 or more (S2). Further, when the engine control unit 50 determines that the engine speed is 4000 or more, the first ignition signal for driving either the first coil unit 10 or the second coil unit 20 is used. Is supplied to each of the igniters 30 and 40 to execute single ignition (S3). Alternatively, when the engine control unit 50 determines that the engine speed is less than 4000 revolutions, the engine control unit 50 outputs the second ignition signal for alternately driving the first coil unit 10 and the second coil unit 20. Multiple ignition is executed by supplying the igniters 30 and 40 (S11).

  In addition, during the single ignition in S3, each of the thermistors 60a, 60b, 70a, 70b includes the primary coils 12, 22, the first igniter 30, and the second igniter 40. A temperature-related detection signal is output to the engine control unit 50 (S4). Further, the engine control unit 50 determines whether or not the detection signal output in S4 exceeds a threshold value (S5). If the detection signal exceeds a threshold value in S5, the engine control unit 50 It is determined whether or not the driven coil unit is the first coil unit 10 (S6).

  When it is determined in S6 that the coil unit currently driven is the first coil unit 10, the engine control unit 50 stops the first coil unit 10 and the second coil unit. The first ignition signal is controlled to drive 20 (S7). Alternatively, when it is determined in S6 that the coil unit currently being driven is the second coil unit 20, the engine control unit 50 stops the second coil unit 20 and the first coil unit. The first ignition signal is controlled to drive 10 (S21).

  Next, referring to FIG. 6, the temperature transition of each of the primary coils 12, 22, the first igniter 30, and the second igniter 40 at the time of performing the single ignition will be described. Each of the primary coils 12, 22, the first igniter 30, and the second igniter 40 operates at a room temperature of about 80 ° C. due to a temperature rise in the engine room due to the operation of the engine. When the single ignition is executed, the first coil unit 10 is driven and the second coil unit 20 is stopped as shown in part (a). However, when the engine speed is high, the temperatures of the first coil unit 10 and the first igniter 30 rise from time to time.

  Eventually, as shown in part (b), when the temperature of the first coil part 10 and the first igniter 30 reaches 130 ° C. which is a first threshold value, the first coil part 10 is stopped and the first coil part 10 is stopped. The second coil unit 20 is driven. Then, the temperature of the stopped first coil unit 10 and the first igniter 30 is lowered, and the temperature of the second coil unit 20 and the second igniter 40 is raised. By repeating this operation, when the temperature of the second coil unit 20 and the second igniter 40 reaches 130 ° C., which is the first threshold value, the first coil unit 10 is driven and the second coil unit 10 is driven. The coil unit 20 is stopped. However, when the engine continues to drive at a high speed, the temperature drop on the side to be stopped does not catch up with the temperature rise on the coil side to be driven as shown in part (c). The temperature difference between 10, 20 and the respective igniters 30, 40 is eliminated. Then, it drives to the 2nd threshold value (140 degreeC) which switches the drive of each said coil part 10 and 20. FIG.

  Then, as shown in part (d), the first coil unit 10 is stopped and the second coil unit 20 is driven, and the temperatures of the second coil unit 20 and the second igniter 40 are When the second threshold value is reached, the first coil unit 10 is driven, and the second coil unit 20 is stopped. Eventually, when the temperature of the first coil unit 10 and the first igniter 30 reaches the second threshold value, the first coil unit 10 is stopped again and the second coil unit 20 is driven. . Further, as shown in part (e), when the temperature difference between each of the coil units 10 and 20 and each of the igniters 30 and 40 disappears, the second switching of driving of the coil units 10 and 20 is performed. Drive to threshold (150 ° C).

  Further, as shown in part (f), the first coil unit 10 is driven to stop the second coil unit 20, and the temperatures of the first coil unit 10 and the first igniter 30 are increased. When the third threshold value is reached, the first coil unit 10 is stopped and the second coil unit 20 is driven. Then, when the temperature of the second coil unit 20 and the second igniter 40 reaches the third threshold value, the first coil unit 10 is driven and the second coil unit 20 is stopped.

  As shown in part (g), when there is no temperature difference between the coil parts 10 and 20 and the igniters 30 and 40, a limit temperature (160) for switching the driving of the coil parts 10 and 20 is obtained. Until it is cooled down. However, each of the coil sections 10 and 20 and each of the igniters 30 and 40 has a limit temperature of 160 ° C. When this limit temperature is exceeded, the output of each of the coil sections 10 and 20 decreases, Failure of igniters 30, 40 occurs. For this reason, as shown in part (h), the first coil part 10 is stopped and the second coil part 20 is driven, and the engine control unit 50 allows the coil parts 10 and 20 to be connected. The length of the first ignition signal to be driven is shortened. As a result, the temperature rise of each of the coil portions 10 and 20 and each of the igniters 30 and 40 is moderate as compared with a case where an ignition signal having a normal length is supplied.

  In addition, the driving coil unit is configured so that the detection signal from the thermistors 60a, 60b, 70a, 70b reaches less than 3% of the limit temperature so that the limit temperature is not reached. The coil portion that is stopped is driven, unlike the coil portion that has been driven. Then, as shown in part (i), when the temperature of the first coil part 10 and the first igniter 30 is lower than the second threshold value, the first coil part 10 is driven and the first coil part 10 is driven. The second coil unit 20 is stopped. Further, the engine control unit 50 returns the ignition signal for driving the coil portions 10 and 20 to a normal length. In the state where the temperature difference between the primary coils 12 and 22 and the igniters 30 and 40 disappears, the temperature difference is less than 1%.

  With the above-described configuration, the first ignition signal supplied when the engine is rotated at a high speed of 4000 revolutions or more is the primary coils 12 and 22, the first igniter 30, and the second ignition signal. When the detection signal related to the temperature of the igniter 40 reaches a threshold value, the coil portions to be driven are switched to thereby increase the temperature of each of the coil portions 10 and 20, the first igniter 30, and the second igniter 40. Suppressing the output and preventing thermal breakdown can be prevented. Further, as shown in FIG. 2A, compared to the conventional invention, in this embodiment, the output value of the secondary current to the spark plug 100 is reduced in the high-speed operation region of the engine that performs single ignition. It is suppressed.

  The engine control unit 50 can precisely control the temperature of the coil units 10 and 20 by setting the first threshold value, the second threshold value, and the third threshold value. . Further, when each of the primary coils 12 and 22, the first igniter 30 and the second igniter 40 approaches the limit temperature, the engine control unit 50 drives the coil units 10 and 20, respectively. By reducing the length of the first ignition signal to be generated, the coil portions 10, 20, the first igniter 30, and the second igniter 40 are prevented from reaching the limit temperature. It is out.

  As a modification of the present invention, an ignition system including the first coil unit 10 and the second coil unit 20 is used. However, as an ignition system having two or more coil units, the detection signal of the thermistor is used as the detection system. It is good also as a structure which restricts and drives the said coil part selected based on. The engine control unit 50 supplies the first ignition signal for performing single ignition when the engine speed is 4000 rpm or more, and the second ignition signal for performing multiple ignition when the engine speed is less than 4000 rpm. However, the predetermined rotational speed for switching between the first ignition signal and the second ignition signal may be changed as appropriate according to the design circumstances such as the engine rev limit rotational speed (overspeed range). Furthermore, the state in which the temperature difference between each of the primary coils 12 and 22 and each of the igniters 30 and 40 is eliminated means that the number of discharges within the discharge period of the coil portion that was driven immediately before is less than three. You may judge from.

10: First coil section
12, 22: Primary coil
14, 24: Secondary coil
16, 26: Iron core
20: Second coil part
30: First igniter
32, 42: Switch element
34, 44: Driver circuit
40: Second igniter
50: Engine control unit
60a, 60b, 70a, 70b: Thermistor
80: Power supply
82: DC-DC converter
90a, 90b: Rectifier
100: Spark plug

Claims (6)

A plurality of coil portions for supplying an output voltage to a common spark plug; a plurality of igniters for individually driving the plurality of coil portions; an engine control unit for providing an ignition signal to each of the plurality of igniters; Is provided corresponding to the plurality of coil units, and a temperature detection unit that outputs a detection signal related to either the temperature of the coil unit itself or the ambient temperature of the coil unit, and
The ignition system for an internal combustion engine, wherein the engine control unit supplies a first ignition signal for driving a limited coil portion selected based on the detection signal among the plurality of coil portions.   The first ignition signal stops the certain coil unit and drives another coil unit different from the certain coil unit when the detection signal related to the certain coil unit among the plurality of coil units reaches a threshold value. The ignition system for an internal combustion engine according to claim 1.   The engine control unit supplies the first ignition signal and a second ignition signal for driving the plurality of coil portions in a predetermined drive pattern. An ignition system for an internal combustion engine as described.   4. The ignition system for an internal combustion engine according to claim 3, wherein the second ignition signal alternately drives a certain coil portion of the plurality of coil portions and another different coil portion. 5. . The first ignition signal is supplied in a region where the rotational speed of the internal combustion engine is equal to or higher than a predetermined set rotational speed,
The ignition system for an internal combustion engine according to claim 3 or 4, wherein the second ignition signal is supplied in a region where the rotational speed of the internal combustion engine is less than a predetermined set rotational speed.   The ignition system for an internal combustion engine according to claim 5, wherein the predetermined set rotational speed is 4000 revolutions.

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