JP2008031933A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of preventing misfire from newly occurring in a cylinder except a cylinder in which misfire has already occurred while inhibiting increase of electric power consumption when misfire of the internal combustion engine is inhibited by controlling turning on and off of a glow plug. <P>SOLUTION: In the control device for the internal combustion engine controlling the internal combustion engine provided with a plurality of cylinders and glow plugs provided in each of the plurality of cylinders, the glow plug is energized to heat an inside of each of the plurality of cylinders, predetermined current-carrying quantity 201 greater than zero is continuously provided to the glow plug of the cylinder in which combustion is stable out of the plurality of cylinders, current-carrying quantity to the glow plug of the cylinder in which combustion is unstable out of the plurality of cylinders is set to a value 202 larger than the predetermined current-carrying quantity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and in particular, when energization of a glow plug is controlled to suppress misfire of the internal combustion engine, an increase in power consumption is suppressed and a misfire is newly generated in a cylinder other than the misfired cylinder. The present invention relates to a control device for an internal combustion engine capable of suppressing the occurrence.

  In a compression ignition type internal combustion engine (diesel engine or the like), in order to improve the startability by increasing the ignitability of the fuel, the cylinder is heated by energizing the glow plugs provided in each cylinder. Even when the inside of the cylinder is heated in this manner, for example, combustion may become unstable and misfire may occur at low temperature start.

  A technique described in Japanese Patent Laid-Open No. 63-75361 (Patent Document 1) is known as a glow plug energization control method for a diesel engine that can reliably prevent a misfire in a cylinder in which a misfire has occurred and can improve low-temperature startability. It has been known. In this publication, in a glow plug energization control method for a diesel engine that controls energization to a glow plug so that the glow temperature becomes a predetermined value, a change in the engine speed is detected, and the misfire of the engine is detected from the detected change. A diesel engine glow plug energization control method is disclosed in which a misfire cylinder is detected, and when a misfire is detected, the glow plug of the misfire cylinder is energized.

  In the glow plug energization control method, normally, as shown in FIG. 6, supply of current to the glow plug is started when the glow temperature is 800 ° C. or lower, and to the glow plug when the glow temperature is 900 ° C. or higher. Current supply is stopped.

  FIG. 7 is a diagram showing the energization state of the glow plug, the glow temperature, and the engine speed in the glow plug energization control method. In FIG. 7, reference numeral 200 denotes a glow temperature. Reference numeral 201 indicates an energized state of the glow plug. Reference numeral 202 indicates the engine speed.

  As described above, normally, when the glow temperature 200 is 800 ° C. or lower, the glow plug energization state 201 is turned on, and when the glow temperature 200 is 900 ° C. or higher, the glow plug energization state 201 is turned off.

  Reference numeral 203 indicates a point in time when a certain cylinder misfires when the energization state 201 of the glow plug is turned off. In the glow plug energization control method, when a misfire is detected, the energization state 201 of the misfired cylinder is immediately turned on even if the energization state 201 of the misfired cylinder is turned off. Thus, the glow current is controlled to flow (the timing for turning on the energization state 201 of the glow plug of the misfired cylinder is not shown). Thereby, the glow temperature becomes high during the next compression stroke of the misfired cylinder, which is said to be effective in suppressing the refire of the misfired cylinder. Note that, in a cylinder that has not misfired, on / off control of the energized state 201 of the above-described normal glow plug is performed according to the glow temperature 200.

JP-A-63-75361 JP 2004-218609 A

  When a misfire occurs in an internal combustion engine, a misfire may newly occur in a cylinder other than the misfired cylinder in addition to the misfired cylinder.

  When the energization of the glow plug is controlled and the misfire of the internal combustion engine is suppressed, not only the misfire is suppressed in the misfired cylinder but also the misfire is more effectively performed in the cylinders other than the misfired cylinder. It is desired that the occurrence of this is suppressed in advance.

  In order to suppress misfire in all the cylinders, the in-cylinder temperature rises as the energization amount to the glow plug of each cylinder increases, so that the effect of suppressing misfire becomes higher. However, as the energization amount for each glow plug is increased, the total energization amount is increased and the electric load is increased. In this case, for example, the power generation amount of the internal combustion engine increases, the load on the internal combustion engine increases, and the fuel consumption deteriorates. For this reason, it is desirable to suppress an increase in power consumption.

  An object of the present invention is to suppress the occurrence of new misfire in cylinders other than the misfired cylinder while suppressing the increase in power consumption when controlling the energization of the glow plug to suppress the misfire of the internal combustion engine. It is an object of the present invention to provide a control device for an internal combustion engine that can be used.

  The control device for an internal combustion engine of the present invention is a control device for an internal combustion engine that controls a plurality of cylinders and a glow plug provided in each of the plurality of cylinders, and energizes the glow plug. And a predetermined energizing amount larger than zero is continuously applied to the glow plugs of the cylinders in which combustion is stable among the plurality of cylinders. The energization amount to the glow plug of the cylinder that is supplied and in which combustion is not stable is set to a value larger than the predetermined energization amount.

  The control device for an internal combustion engine of the present invention is a control device for an internal combustion engine that controls a plurality of cylinders and a glow plug provided in each of the plurality of cylinders, and energizes the glow plug. The cylinders of each of the plurality of cylinders are heated, and the temperature of the glow plug of a cylinder in which combustion is stable among the plurality of cylinders is set to a predetermined temperature, and the plurality of cylinders Among these, the temperature of the glow plug of the cylinder in which combustion is not stable is set to a temperature higher than the predetermined temperature.

  The control apparatus for an internal combustion engine according to the present invention, wherein the predetermined energization amount is such that when there is a cylinder in which combustion is not stable among the plurality of cylinders, there is a cylinder in which combustion is not stable. It is characterized in that it is set to a larger value than the case where it is not.

  In the control apparatus for an internal combustion engine according to the present invention, when the predetermined temperature is a cylinder in which the combustion is not stable among the plurality of cylinders, there is no cylinder in which the combustion is not stable. It is characterized by being set to a larger value than the case.

  In the control device for an internal combustion engine according to the present invention, whether or not combustion is stable in each of the plurality of cylinders is determined based on a change in the rotational speed of the internal combustion engine.

  In the control apparatus for an internal combustion engine according to the present invention, whether or not combustion is stable in each of the plurality of cylinders is determined based on whether or not misfire has been detected.

  According to the control device for an internal combustion engine of the present invention, when energization of the glow plug is controlled to suppress misfire of the internal combustion engine, a misfire is newly generated in cylinders other than the misfired cylinder while suppressing an increase in power consumption. It is possible to suppress the occurrence beforehand.

  Hereinafter, an embodiment of a control device for an internal combustion engine of the present invention will be described in detail with reference to the drawings.

(First embodiment)
The first embodiment will be described with reference to FIGS. 1 to 3. The present embodiment relates to a control device for an internal combustion engine that controls energization of a glow plug to suppress misfire of the internal combustion engine.

  FIG. 1 is a diagram showing a set value of the energization amount for the glow plug of the present embodiment. In FIG. 1, reference numeral 100 indicates an energization amount to a glow plug of a misfired cylinder (hereinafter referred to as a misfire cylinder). Reference numeral 101 denotes an energization amount for a glow plug of a cylinder that has not misfired (hereinafter referred to as a non-misfire cylinder). A symbol Ta indicates a point in time when a misfire is detected.

  As shown in FIG. 1, in the first embodiment, in the compression ignition type engine (internal combustion engine), as indicated by the energization amount 101 to the glow plug of the non-misfire cylinder, the glow plug of the non-misfire cylinder is more than zero. The first energizing amount 201 having a larger value is continuously supplied. When misfiring occurs in the engine at the time indicated by the reference symbol Ta, as shown in the energization amount 100 to the glow plug of the misfire cylinder, the first energization amount 201 larger than the first energization amount 201 is applied to the glow plug of the misfire cylinder. Two energization amounts 202 are continuously supplied. That is, the energization amount 100 for the glow plug of the misfire cylinder is set to a larger value after the misfire occurs than before the misfire occurs.

  By setting the energization amount to the glow plug as described above, it is possible not only to suppress the misfire again in the misfire cylinder, but also to prevent the misfire from newly occurring in the non-fire cylinder. The reason is as follows.

  Energization is continuously applied to the glow plug of the non-misfire cylinder. Therefore, compared with a case where the glow plug of the non-misfire cylinder is not energized continuously, the inside of the cylinder of the non-misfire cylinder is constantly kept at a high temperature, so that the combustion is stabilized. As a result, the occurrence of a new misfire in the non-misfire cylinder is effectively suppressed in advance.

  When a misfire occurs newly in the non-misfire cylinder at time Ta and changes to a misfire cylinder, the energization amount 100 for the glow plug of the misfire cylinder is changed from the first energization amount 201 before misfire to the second energization amount 201. The energization amount 202 is changed. Since the first energization amount 201 was continuously supplied to the glow plug of the cylinder that changed from the non-misfire cylinder to the misfire cylinder at time Ta, before the misfire occurred, the glow plug was not continuously energized. Compared to the case, the inside of the cylinder is constantly kept at a high temperature.

  For this reason, when the energization amount 100 for the glow plug of the cylinder changed to the misfiring cylinder at the time Ta is set to the second energization amount 202, compared to the case where the glow plug was not energized continuously before the time Ta. In a short time, the temperature in the cylinder can be raised to a temperature at which misfire is suppressed. Accordingly, it is possible to effectively suppress the occurrence of misfire again in the cylinder that has been changed to the misfire cylinder at the time Ta, as compared with the case where the glow plug of the non-misfire cylinder is not continuously energized.

  In order to suppress misfire in all the cylinders, the in-cylinder temperature rises as the energization amount to the glow plug of each cylinder increases, so that the effect of suppressing misfire becomes higher. However, when the energization amount for all the glow plugs is uniformly set to a large value, there is a problem that power consumption increases.

  On the other hand, in the present embodiment, the second energization amount 202 is supplied to the glow plug of the misfire cylinder, while the first energization amount 201 is continuously applied to the glow plug of the non-misfire cylinder. To be supplied. In the misfire cylinder, misfire has already occurred, and it is expected that there is a high possibility that the misfire will occur again later than in the non-misfire cylinder. Therefore, a relatively large second energization amount 202 is supplied to the glow plug of the misfire cylinder. Thereby, compared with the case where the energization amount with respect to all the glow plugs is uniformly set to a large value, an increase in power consumption is suppressed.

  FIG. 2 is a schematic configuration diagram of an apparatus according to the present embodiment. In FIG. 2, reference numeral 1 denotes an engine. The engine 1 has four cylinders 2 (first cylinder 2a, second cylinder 2b, third cylinder 2c, and fourth cylinder 2d). The engine 1 of this embodiment is a four-cycle engine. A piston 3 that can reciprocate inside the cylinder 2 is provided inside the cylinder 2. A combustion chamber 5 is formed above the piston 3.

  Each of the cylinders 2 is provided with a glow plug 4 (a first glow plug 4a, a second glow plug 4b, a third glow plug 4c, and a fourth glow plug 4d). When a current is passed through the glow plug 4, the glow plug 4 generates heat and the inside of each cylinder 2 is heated. The glow plug 4 is connected to a glow control unit (GCU) 10. The amount of energization for each of the glow plugs 4 is controlled by the GCU 10.

  A vehicle (not shown) on which the engine 1 is mounted is provided with a vehicle control unit 20 having an ECU (Electronic Control Unit) that controls each part of the vehicle. The vehicle is provided with a rotation speed sensor 15 that detects the rotation speed of the engine 1. The rotational speed sensor 15 is connected to the vehicle control unit 20, and the detection result by the rotational speed sensor 15 is input to the vehicle control unit 20. The GCU 10 is connected to the vehicle control unit 20, and the command value of the energization amount for each of the glow plugs 4 is output from the vehicle control unit 20 to the GCU 10.

  Energization of the glow plug 4 is performed to heat the inside of the cylinder and improve the ignition performance of the fuel to improve the startability. The energization of the glow plug 4 is roughly classified into energization before starting the engine 1 (pre-glow) and energization at the time of starting and after the engine 1 (after glow).

  In the present embodiment, all the glow plugs 4 are continuously energized during the after glow. During the afterglow, it is periodically determined whether or not the combustion of each cylinder 2 is stable. As a result of the determination, the energization amount to the glow plug 4 of the cylinder (misfire cylinder) 2 determined that the combustion is not stable is the glow plug of the cylinder (non-fire cylinder) 2 determined to be stable in combustion. 4 is set to a value larger than the energization amount for 4.

  FIG. 3 is a flowchart showing the operation of the present embodiment.

  In step S10, it is determined whether the afterglow is currently in progress. As a result of the determination, if it is determined that the after-glow is being performed (Yes in Step S10), it is next determined whether or not the combustion of each cylinder 2 is stable. The determination is made based on the result of determination (misfire determination) on whether or not misfire has occurred in the cylinder 2. The misfire determination is performed by a known method that is performed based on the rotation speed (angular velocity) of the engine 1. For example, the misfire determination is performed by the following method.

  A predetermined crank angle range corresponding to each of the four cylinders 2 is set in one cycle of the engine 1. The range of the predetermined crank angle is set to a range in which the rotation speed is likely to change when a misfire occurs in the cylinder 2 (for example, a predetermined crank angle range in the expansion stroke). Since the engine 1 of the present embodiment is a four-cycle type, each expansion stroke of the cylinder 2 is performed at different timings in one cycle of the engine 1. Therefore, for each of the four cylinders 2, the predetermined crank angle range (four) in one cycle of the engine 1 is set to a different range.

  Angular velocities in the range of the four predetermined crank angles are detected for each cycle of the engine 1. Based on the comparison result between the angular velocity detected in the previous cycle and the angular velocity detected in the current cycle in each of the predetermined crank angle ranges, it is determined whether or not misfiring has occurred in the corresponding cylinder 2. Done.

  Based on the result of the misfire determination performed as described above, it is determined whether or not the combustion is stable in each of the cylinders 2 (steps S20, S50, S80, and S110). The determination as to whether or not the combustion is stable is performed, for example, according to the combustion order of the cylinders 2. Here, a case where the misfire determination is first performed in the first cylinder 2a will be described.

  If it is determined in step S20 that no misfire has occurred in the first cylinder 2a as a result of the misfire determination, it is determined that the combustion in the first cylinder 2a is stable (Yes in step S20). In this case, in step S30, the energization amount for the first glow plug 4a of the first cylinder 2a is set to a predetermined first energization amount 201 (see FIG. 1).

  The first energization amount 201 is set to a value that can suppress the occurrence of misfire in the non-misfire cylinder 2. Specifically, the first energization amount 201 is the temperature in the cylinder to the extent that stable combustion is continued when the energization amount for the glow plug 4 of the non-misfire cylinder 2 is set to the first energization amount 201. Is set to such a value that can be increased. The first energization amount 201 is set based on the result of an actual machine test, for example.

  On the other hand, when it is determined in step S20 that the combustion is not stable (misfire has occurred) in the first cylinder 2a (No in step S20), the first glow plug of the first cylinder 2a is determined in step S40. The energization amount for 4a is set to a predetermined second energization amount 202 (see FIG. 1).

  The second energization amount 202 is set to a value larger than the first energization amount 201. The second energization amount 202 suppresses the occurrence of misfire again when the in-cylinder temperature sufficiently rises when the energization amount to the glow plug 4 of the misfire cylinder 2 is set to the second energization amount 202. Set to the value to be The second energization amount 202 can be, for example, the upper limit value of the energization amount in the glow plug 4 (the upper limit value of the energization amount according to the standard of the product). In this case, by setting the energization amount to the first glow plug 4a of the misfired first cylinder (misfire cylinder) 2a to the second energization amount 202, the inside of the cylinder is heated as much as possible, and the misfire cylinder 2a The occurrence of misfire again is effectively suppressed.

  After the processing of step S20 and step S30 or step S40 is performed in the first cylinder 2a, whether or not the combustion is stable in the cylinders 2 other than the first cylinder 2a as well as the first cylinder 2a according to the combustion order. The energization amount for the glow plug 4 is set accordingly. When the energization amount for the glow plug 4 is set in all the cylinders 2, the process proceeds to step S10 again.

  If it is determined in step S10 that the afterglow is not in progress (No in step S10), the control flow ends.

  According to the present embodiment, when a misfire occurs in the engine 1 during the after glow (step S10 affirmative) (steps S20, S50, S80, S110—No), the energization amount to the glow plug 4 of the misfire cylinder 2 is increased. The second energization amount 202 is set (steps S40, S70, S100, S130). The energization amount for the glow plug 4 of the non-misfire cylinder 2 is set to the first energization amount 201 (steps S30, S60, S90, S120).

  The first energization amount 201 is continuously supplied to the glow plug 4 of the non-misfire cylinder 2 (steps S30, S60, S90, S120), so that the glow plug 4 of the non-fire cylinder 2 is continuously supplied. In comparison with the case where the energization is not performed, the cylinder of the non-misfire cylinder 2 is constantly kept at a high temperature and the combustion is kept stable. As a result, the occurrence of a new misfire in the non-misfire cylinder 2 is suppressed in advance.

  In the case where the misfire has newly occurred in the non-misfire cylinder 2 in which combustion has been stable until then, and the misfire cylinder 2 is changed to the misfire cylinder 2 (No in steps S20, S50, S80, S110), the cylinder 2 which has newly become the misfire cylinder 2 The energization amount for the glow plug 4 is set to the second energization amount 202 (steps S40, S70, S100, S130). The glow plug 4 of the cylinder 2 which has newly become a misfire cylinder is continuously energized with the first energization amount 201 before misfire has occurred, and thus when the energization is not continuously performed Compared to the above, the inside of the cylinder is constantly kept at a high temperature. For this reason, when the energization amount for the glow plug 4 of the cylinder 2 that has newly become a misfire cylinder is set to the second energization amount 202, the temperature in the cylinder is quickly increased to a temperature at which misfire is suppressed, It is suppressed that misfire occurs again.

  By suppressing the occurrence of misfire in each of the cylinders 2 as described above, the combustion of the engine 1 during the afterglow is stabilized.

  Since the energization amounts for the glow plugs 4 of the respective cylinders 2 are controlled based on the determination result of whether or not the combustion is stable, when the energization amounts for all the glow plugs 4 are uniformly set to a large value. In comparison, an increase in power consumption can be suppressed.

  By suppressing the increase in power consumption, the electric load is reduced, and the amount of power generated by an alternator (not shown) can be reduced. As a result, the load on the engine 1 is reduced and fuel efficiency is improved. Further, as the electric load is reduced as described above, a sufficient current is supplied to the starter motor (not shown) at the time of starting. Thereby, rotation of a starter motor becomes high and the startability of the engine 1 improves.

  In the present embodiment, when it is determined whether or not the combustion of the cylinder 2 is stable (steps S20, S50, S80, and S110), the determination is performed depending on whether or not misfire has occurred. Alternatively, the determination can be made based on the degree of combustion instability. The degree of instability of combustion can be determined based on, for example, the degree of change in the detected engine speed (angular velocity) for each cycle. In this case, for example, when the degree of change is larger than the degree of change when combustion is sufficiently stable and smaller than the degree of change when it is determined that misfiring has occurred, It is determined that the combustion is not stable.

  By determining whether or not the combustion in the cylinder 2 is stable in this way, even if no misfire has occurred in the cylinder 2, if the combustion state is unstable, the combustion in the cylinder 2 is stable. (No in steps S20, S50, S80, S110) and the energization amount for the glow plug 4 of the cylinder 2 is set to the second energization amount 202 (steps S40, S70, S100, S130). As a result, the temperature in the cylinder of the cylinder 2 where the combustion is not stable rises so that the combustion is stabilized, and it is possible to effectively suppress the occurrence of misfire in the cylinder 2 beforehand.

  In this embodiment, the energization amount to the glow plug 4 is controlled based on the determination result of whether or not the combustion of the cylinder 2 is stable. Instead, whether or not the combustion of the cylinder 2 is stable. Based on the determination result, the temperature of the glow plug 4 (glow temperature) can be controlled. In this case, for example, the glow temperature of the glow plug 4 of the cylinder (misfire cylinder) 2 where combustion is not stable is higher than the glow temperature of the glow plug 4 of the cylinder (non-fire cylinder) 2 where combustion is stable. Control is performed. The glow temperature of the glow plug 4 of the non-misfire cylinder 2 is controlled to a glow temperature at which the temperature in the cylinder can be maintained to the extent that stable combustion is continued.

(Second Embodiment)
The second embodiment will be described with reference to FIGS. 4 and 5. In the second embodiment, only differences from the first embodiment will be described. The mechanical configuration of the second embodiment is the same as that of the first embodiment.

  In the first embodiment (FIG. 1), the energization amount of the non-misfire cylinder 2 to the glow plug 4 includes the case where the misfire cylinder 2 is present among the plurality of cylinders of the engine 1 and the case where the misfire cylinder 2 is not present. And the same value (first energization amount 201).

  Instead, in the second embodiment, as shown in FIG. 4, when misfire occurs among the plurality of cylinders and the misfire cylinder 2 exists, before the misfire cylinder 2 exists. In comparison, the energization amount for the glow plug 4 of the non-misfire cylinder 2 other than the misfire cylinder 2 is set to a large value.

  FIG. 4 is a diagram illustrating a set value of the energization amount for the glow plug 4 in the second embodiment. In the present embodiment, three energization amounts (a third energization amount 203, a fourth energization amount 204, and a fifth energization amount 205) are set as energization amounts for the glow plug 4. As shown in FIG. 4, the third energization amount 203 is set to the smallest value among the three energization amounts, which is greater than zero. The third energization amount 203, the fourth energization amount 204, and the fifth energization amount 205 are set to large values in that order.

  In FIG. 4, reference numeral 102 indicates an energization amount for the glow plug 4 of the misfire cylinder 2. Reference numeral 103 indicates an energization amount to the glow plug 4 of the non-misfire cylinder 2. Reference numeral Tb indicates a point in time when misfire occurs among the plurality of cylinders of the engine 1 and the misfire cylinder 2 is present.

  The energization amount 102 for the glow plug 4 of the misfire cylinder 2 is changed from the third energization amount 203 to the fifth energization amount 205 at time Tb. The energization amount 103 for the glow plug 4 of the non-misfire cylinder 2 is changed from the third energization amount 203 to the fourth energization amount 204 at time Tb.

  When the misfire cylinder 2 does not exist in the plurality of cylinders of the engine 1 (before time Tb), the third energization amount 203 is continuously supplied to the glow plugs 4 of all the cylinders 2. At time Tb, when a misfire occurs among the plurality of cylinders and a misfire cylinder exists, the energization amount of each of the non-fire cylinder 2 and the misfire cylinder 2 is set to the following values. The

  The energization amount 103 for the glow plug 4 of the non-misfire cylinder 2 is set to a fourth energization amount 204. The energization amount 102 for the glow plug 4 of the misfire cylinder 2 is set to a fifth energization amount 205.

  The energization amount 103 to the glow plug 4 of the non-misfire cylinder 2 is set to a value greater than that before the time Tb (third energization amount 203) after time Tb (fourth energization amount 204). The temperature in the cylinder No. 2 can be higher after time Tb than before time Tb. As a result, the combustion state in the non-misfire cylinder 2 is more stable after the time Tb than before the time Tb, so that a new misfire in the non-fire cylinder 2 is suppressed in advance.

  Even if a new misfire occurs in the non-misfire cylinder 2 after the time Tb, in this embodiment, the misfire again is prevented from occurring in the cylinder 2 that newly becomes the misfire cylinder.

  In FIG. 4, the symbol Tc is changed from the non-misfire cylinder 2 to the misfire cylinder 2 due to a new misfire in the non-fire cylinder 2 in which combustion has been stable until then, in addition to the cylinder 2 that has become a misfire cylinder at the time Tb. Indicates the point. The energization amount of the cylinder 2 that newly becomes the misfire cylinder at time Tc is changed from the fourth energization amount 204 to the fifth energization amount 205 as indicated by reference numeral 301. In the cylinder 2 that newly becomes a misfire cylinder at the time Tc, the misfire is suppressed from occurring again for the following reason.

  First, as described above, the combustion state in the non-misfire cylinder 2 is more stable after the time Tb than before the time Tb, so that the inertial force of the engine 1 is increased. As a result, the compressive force acts strongly on the air in the cylinder 2 of the cylinder 2 that newly becomes the misfire cylinder at the time Tc. As a result, the in-cylinder temperature of the cylinder 2 that newly becomes the misfire cylinder at the time Tc is increased, so that the misfire again is suppressed from occurring in the cylinder 2 that newly becomes the misfire cylinder at the time Tc.

  Secondly, the glow plug 4 of the cylinder 2 that has newly become a misfired cylinder at the time Tc is continuously energized with the fourth energization amount 204 from before the time Tc. The inside of the cylinder is constantly kept at a high temperature as compared with the case where it is not performed. For this reason, when the energization amount for the glow plug 4 of the cylinder 2 that has newly become a misfire cylinder at the time Tc is set to the fifth energization amount 205, the temperature in the cylinder is quickly increased to a temperature at which misfire is suppressed. It is suppressed that misfire occurs again.

  Note that, in the cylinder 2 that has become a misfire cylinder at the time Tb, for the same reason as the first reason, the temperature in the cylinder is further increased and the misfire is suppressed from occurring again.

  FIG. 5 is a flowchart showing the operation of the second embodiment.

  In step S210, it is determined whether the afterglow is currently in progress. As a result of the determination, if it is determined that the afterglow is being performed (Yes at Step S210), it is next determined whether or not the combustion of each cylinder 2 is stable. Whether the combustion is stable is determined based on the result of the misfire determination, as in the first embodiment. Here, a case will be described in which it is first determined whether or not combustion is stable in the first cylinder 2a.

  If it is determined in step S220 that no misfire has occurred in the first cylinder 2a as a result of the misfire determination, it is determined that the combustion in the first cylinder 2a is stable (Yes in step S220). In this case, next, in step S225, it is determined whether or not the combustion is stable in all the cylinders 2. It is determined that the combustion is stable in all the cylinders 2 when it is determined that no misfire has occurred in any of the cylinders 2 as a result of the misfire determination.

  As a result of the determination in step S225, when it is determined that the combustion is stable in all the cylinders 2 (Yes in step S225), in step S230, the energization amount to the first glow plug 4a of the first cylinder 2a is It is set to a predetermined third energization amount 203 (see FIG. 4).

  The third energization amount 203 is set to a value that can suppress the occurrence of misfire in the non-misfire cylinder 2. Specifically, the third energization amount 203 is the temperature inside the cylinder to the extent that stable combustion is continued when the energization amount for the glow plug 4 of the non-misfire cylinder 2 is set to the third energization amount 203. Is set to such a value that can be increased. The third energization amount 203 can be the same value as the first energization amount 201 in the first embodiment.

  On the other hand, as a result of the determination in step S225, if it is determined that combustion is not stable in all the cylinders 2 (there is cylinder 2 determined to have misfired) (No in step S225), step S235 is performed. , The energization amount for the first glow plug 4a of the first cylinder 2a is set to a predetermined fourth energization amount 204 (see FIG. 4).

  If it is determined in step S220 that the combustion in the first cylinder 2a is not stable (misfire has occurred) (No in step S220), in step S240, the first cylinder 2a is turned on. The energization amount for one glow plug 4a is set to a predetermined fifth energization amount 205 (see FIG. 4).

  The fifth energization amount 205 suppresses the occurrence of misfire again when the in-cylinder temperature rises sufficiently when the energization amount to the glow plug 4 of the misfire cylinder 2 is set to the fifth energization amount 205. Set to the value to be As the fifth energization amount 205, the same value as the second energization amount 202 in the first embodiment can be used. The fifth energization amount 205 can be, for example, the upper limit value of the energization amount in the glow plug 4 (the upper limit value of the energization amount according to the standard of the product).

  After the energization amount for the first glow plug 4a is set in the first cylinder 2a, in the cylinders 2 other than the first cylinder 2a, the same determination as that in the first cylinder 2a is performed according to the combustion order. The energization amount for each of the glow plugs 4 is set. When the energization amount for the glow plug 4 is set in all the cylinders 2, the process proceeds to step S210 again.

  If it is determined in step S210 that the afterglow is not in progress (No in step S210), the control flow ends.

  According to the second embodiment, during afterglow (Yes at Step S210), when misfire occurs among the plurality of cylinders and the misfire cylinder 2 exists (Steps S220, S250, S280, S310—No). The energization amount for the glow plug 4 of the misfire cylinder 2 is set to the fifth energization amount 205 (steps S240, S270, S300, S330). In this case, the energization amount for the glow plug 4 of the non-misfire cylinder 2 is set to the fourth energization amount 204 (steps S235, S265, S295, S325). When it is determined that the combustion is stable in all the cylinders 2 (steps S225, S255, S285, S315—Yes), the energization amount to the glow plug 4 of the non-misfire cylinder 2 is the third energization. The amount 203 is set (steps S230, S260, S290, S320).

  When misfiring occurs among a plurality of cylinders and misfiring cylinders are present (point Tb in FIG. 4), the energization amount to the glow plug 4 of the non-misfire cylinder 2 is before time Tb after time Tb. Therefore, the temperature in the cylinder of the non-misfire cylinder 2 can be higher after the time Tb than before the time Tb. As a result, the combustion state in the non-misfire cylinder 2 is more stable after time Tb than before time Tb, so that a new misfire is prevented from occurring in the non-fire cylinder 2 in advance.

  Further, in addition to the cylinder 2 that became the misfire cylinder at time Tb, a new misfire occurred in the non-misfire cylinder 2 in which combustion was stable until then, and the misfire cylinder 2 was changed to the misfire cylinder 2 (FIG. 4). In the case of (Tc point), for the following reason, it is suppressed that the misfire again occurs in the cylinder 2 that newly becomes the misfire cylinder at the time Tc.

  First, as described above, the combustion state in the non-misfire cylinder 2 is more stable after the time Tb when the misfire cylinder 2 is present than before the time Tb, so that the inertial force of the engine 1 is increased. As a result, the compressive force acts strongly on the air in the cylinder 2 of the cylinder 2 that newly becomes the misfire cylinder at the time Tc. As a result, the in-cylinder temperature of the cylinder 2 that newly becomes the misfire cylinder at the time Tc is increased, so that the misfire again is suppressed from occurring in the cylinder 2 that newly becomes the misfire cylinder at the time Tc.

  Second, since the glow plug 4 of the cylinder 2 that has newly become a misfire cylinder at time Tc is continuously energized with the fourth energization amount 204 from before the time Tc at which misfire occurs. The inside of the cylinder is constantly kept at a high temperature as compared with the case where energization is not continuously performed. For this reason, when the energization amount for the glow plug 4 of the cylinder 2 that has newly become a misfire cylinder at the time Tc is set to the fifth energization amount 205, the temperature in the cylinder is quickly increased to a temperature at which misfire is suppressed. It is suppressed that misfire occurs again.

  Note that, in the cylinder 2 that has become a misfire cylinder at the time Tb, for the same reason as the first reason, the temperature in the cylinder is further increased and the misfire is suppressed from occurring again.

  In the present embodiment, as in the first embodiment, since the energization amount to the glow plugs 4 of the respective cylinders 2 is controlled based on the determination result of whether or not the combustion is stable, all the glow plugs 4 are controlled. The increase in power consumption can be suppressed as compared with the case where the energization amount for is uniformly set to a large value.

  In this embodiment, when it is determined whether or not the combustion of the cylinder 2 is stable (steps S220, S250, S280, and S310), the determination is made based on whether or not misfire has occurred. Instead, the determination can be made based on the degree of instability of combustion, as in the first embodiment. As a result, the occurrence of misfire in the cylinder 2 can be effectively suppressed in advance.

  In the present embodiment, the energization amount to the glow plug 4 is controlled based on the determination result of whether or not the combustion of the cylinder 2 is stable. Instead, whether or not the combustion of the cylinder 2 is stable. Based on the determination result, the temperature of the glow plug 4 (glow temperature) can be controlled.

It is a figure for demonstrating the control method in 1st Embodiment of the control apparatus of the internal combustion engine of this invention. It is a schematic block diagram of the apparatus which concerns on 1st Embodiment of the control apparatus of the internal combustion engine of this invention. It is a flowchart which shows operation | movement of 1st Embodiment of the control apparatus of the internal combustion engine of this invention. It is a figure for demonstrating the control method in 2nd Embodiment of the control apparatus of the internal combustion engine of this invention. It is a flowchart which shows operation | movement of 2nd Embodiment of the control apparatus of the internal combustion engine of this invention. It is a figure which shows an example of the energization control method of a glow plug. It is a figure which shows an example of the glow plug energization control method which supplies with electricity to the glow plug of the cylinder which misfired.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 2a 1st cylinder 2b 2nd cylinder 2c 3rd cylinder 2d 4th cylinder 3 Piston 4 Glow plug 4a 1st glow plug 4b 2nd glow plug 4c 3rd glow plug 4d 4th glow plug 5 Combustion chamber 10 GCU (Glow control unit)
DESCRIPTION OF SYMBOLS 15 Rotational speed sensor 20 Vehicle control part 100 Energization amount with respect to glow plug of misfire cylinder 101 Energization amount with respect to glow plug of non-misfire cylinder 102 Energization amount with respect to glow plug of misfire cylinder 103 Energization amount with respect to glow plug of non-misfire cylinder 201 First Energization amount 202 Second energization amount 203 Third energization amount 204 Fourth energization amount 205 Fifth energization amount 301 Change of energization amount Ta Time when misfire is detected Tb Time when misfire is detected Tc Misfire is detected When

Claims (6)

A control device for an internal combustion engine for controlling an internal combustion engine comprising a plurality of cylinders and a glow plug provided in each of the plurality of cylinders,
The glow plug is energized to heat each cylinder of the plurality of cylinders,
A predetermined predetermined energization amount larger than zero is continuously supplied to the glow plug of the cylinder in which combustion is stable among the plurality of cylinders,
The control device for an internal combustion engine, wherein an energization amount to the glow plug of a cylinder in which combustion is not stable among the plurality of cylinders is set to a value larger than the predetermined energization amount. A control device for an internal combustion engine for controlling an internal combustion engine comprising a plurality of cylinders and a glow plug provided in each of the plurality of cylinders,
The glow plug is energized to heat each cylinder of the plurality of cylinders,
The temperature of the glow plug of the cylinder in which combustion is stable among the plurality of cylinders is set to a predetermined temperature,
The control apparatus for an internal combustion engine, wherein a temperature of the glow plug of a cylinder in which combustion is not stable among the plurality of cylinders is set to a temperature higher than the predetermined temperature. A control device for an internal combustion engine according to claim 1,
The predetermined energization amount is set to a larger value when there is a cylinder with unstable combustion among the plurality of cylinders than when there is no cylinder with unstable combustion. A control device for an internal combustion engine characterized by the above. A control device for an internal combustion engine according to claim 2,
The predetermined temperature is set to a larger value when there is a cylinder where the combustion is not stable among the plurality of cylinders than when there is no cylinder where the combustion is not stable. A control device for an internal combustion engine. The control apparatus for an internal combustion engine according to any one of claims 1 to 4,
Whether the combustion is stable in each of the plurality of cylinders is determined based on a change in the rotational speed of the internal combustion engine. The control apparatus for an internal combustion engine according to any one of claims 1 to 4,
Whether or not combustion is stable in each of the plurality of cylinders is determined based on whether or not misfire has been detected.

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