Controller of internal combustion engine

A glow plug is provided in a combustion chamber of a diesel engine. An ECU diagnoses existence or nonexistence of a disconnection abnormality of the glow plug through a controller. When there is an abnormality in the glow plug, processing for cutting fuel supply of an abnormal cylinder, processing for increasing fuel injection quantity of a normal cylinder, processing for delaying injection timing of the abnormal cylinder, or processing for delaying valve timing of an intake valve of the abnormal cylinder is performed. Thus, suitable startability of the engine can be ensured even when the abnormality occurs in the glow plug.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2006-301053 filed on Nov. 7, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a controller that controls an output of an internal combustion engine having a heat generating unit projecting into a combustion chamber

2. Description of Related Art

This kind of controller is shown, for example, in Patent Document 1 (JP-A-H11-82271). The controller has an electrode for ion detection disposed at a tip end of a heat generating unit (glow plug) in a conductive manner with a heating element. The controller determines an existence or nonexistence of a disconnection abnormality of the glow plug based on whether a current flows between the ion detection electrode and an inner wall of a combustion chamber. Thus, the existence or nonexistence of the disconnection abnormality of the glow plug can be determined appropriately.

The above-described structure can detect the disconnection of the glow plug but cannot cope with the disconnection when the disconnection actually arises. That is, when the disconnection arises, there is a possibility that starting cannot be performed unless the glow plug is replaced. Even if the starting is possible, there is a possibility that black lead is discharged because of incomplete combustion.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a controller of an internal combustion engine capable of securing good startability even when an abnormality of a heat generating unit occurs.

According to an aspect of the present invention, a controller has a changing device that changes an operation mode of an actuator of an internal combustion engine to control a state quantity in a combustion chamber of the engine such that lowering of startability due to an abnormality in a heat generating unit is compensated on the occasion of starting of the engine if the abnormality is detected.

With the above-described structure, the state quantity in the combustion chamber can be changed by changing the operation mode of the actuator from a mode in the case of a normality with the changing device. Therefore, lowering of the startability due to the abnormality in the heat generating unit can be compensated, and the startability can be improved.

The state quantity is a fuel quantity, an air inflow quantity or temperature in the combustion chamber, for example.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Referring toFIG. 1, a controller of an internal combustion engine according to a first embodiment of the present invention applied to a controller of a vehicular diesel engine is illustrated.FIG. 1is a structural diagram showing an engine system according to the present embodiment. As shown inFIG. 1an intake passage12of the diesel engine10communicates with a combustion chamber20by an opening operation of an intake valve14. The combustion chamber20is defined by a cylinder block16and a piston18. A tip end portion of an injector22projects into the combustion chamber20. Thus, injection supply of fuel to the combustion chamber20is enabled. A glow plug24as a heat generating unit projecting into the combustion chamber20is provided in the combustion chamber20.

If the fuel is injected into the combustion chamber20, the fuel causes self-ignition due to compression of the combustion chamber20, and energy is generated. The energy is taken out as rotational energy of an output shaft (crankshaft26) of the diesel engine10through the piston18. A crank angle sensor28for sensing a rotation angle of the crankshaft26is provided near the crankshaft26. A coolant flows through the cylinder block16to suppress the temperature increase of the diesel engine10due to the combustion of the fuel. A coolant temperature sensor30for sensing the temperature of the coolant is provided to the cylinder block16.

After the fuel is injected into the combustion chamber20through the injector22and the combustion arises, a gas used in the combustion is discharged to an exhaust passage32as exhaust gas through an opening operation of an exhaust valve31.

The opening and closing drive of both the above-described intake valve14and the exhaust valve31is performed by the torque of the crankshaft26. Specifically, a variable valve timing device36that varies a rotation phase difference of an intake side camshaft34with respect to the crankshaft26is provided to the intake valve14. A cam angle sensor37for sensing a rotation angle of the intake side camshaft34is provided near the intake side camshaft34.

An electronic control unit (ECU40) operates the various actuators such as the injector22based on the sensing values of the various sensors sensing the operation states of the diesel engine10and requests of a user. Thus, the ECU40controls output characteristics (output torque, exhaust characteristic) of the diesel engine10. Specifically the ECU40operates a temperature state of the glow plug24through a controller50. Furthermore, the ECU40performs abnormality diagnosis of the glow plug24through the controller50and outputs the result on a display45when the abnormality arises.

FIG. 2shows structures of the ECU40and the controller50. As shown inFIG. 2, since a four-cylinder engine is assumed as the diesel engine10in the present embodiment, four glow plugs24for the respective cylinders are provided. The controller50has switching elements SW1-SW4each consisting of a MOS transistor. The switching elements SW1-SW4provide/intercept conduction between a battery B and the glow plugs24respectively. A control circuit51is activated when an ignition switch IG is turned on (i.e., brought to an ON state). The control circuit51operates each of conduction control terminals (gates) of the switching elements SW1-SW4based on a command signal from the ECU40. Thus, the control circuit51controls the conduction state of each of the switching elements SW1-SW4.

Resistors R1-R4are connected to the glow plugs24of the respective cylinders in parallel. Quantities of voltage drops due to the resistors R1-R4are taken into a current detection circuit52. The current detection circuit52detects quantity of current flowing through each glow plug24of each cylinder based on the quantity of the voltage drop. These sensing results are outputted to a temperature detection circuit53and a disconnection detection circuit54.

The temperature detection circuit53indirectly senses the temperature Tg of the glow plug24of each cylinder based on the current which flows through the glow plug24of the cylinder. That is, since the resistance R of the glow plug24has temperature dependency as shown inFIG. 3, the temperature Tg of the glow plug24can be indirectly sensed based on the resistance R. In detail, the resistance R of the glow plug24is calculated from the voltage value applied to the glow plug24and the current value which flows through the glow plug24. Then, the temperature Tg of the glow plug24is indirectly sensed based on the resistance R.FIG. 3shows that the resistance R increases with the rise of the temperature Tg of the glow plug24.

The disconnection detection circuit54detects an existence or nonexistence of a disconnection abnormality in a closed loop circuit including the glow plug24based on whether the current flows through the glow plug24of each cylinder. The detection result of the existence or nonexistence of the disconnection abnormality is outputted to the ECU40as diagnostic information through the control circuit51.

The ECU40takes in the signal about the temperature of the glow plug24, the output signal of the coolant temperature sensor30, and also the voltage value of the battery B. The ECU40changes these into digital data with an A/D converter41. The digital data outputted by the A/D converter41is taken into a microcomputer42. The microcomputer42generates the above-described command signal based on these input data, and outputs the command signal to the controller50through an output circuit43. The diagnostic information outputted by the controller50and the state of the ignition switch IG are taken into the microcomputer42through an input circuit44.

A procedure of the energization processing applied to the glow plug24is shown inFIG. 4. This processing is started and performed by the ECU40when the ignition switch IG is brought to the ON state. In a series of the processing, first, energization periods tp, ta are calculated in Step S10based on the coolant temperature Tw sensed by the coolant temperature sensor30. The energization period tp sets the upper limit period for continuing the energization of the glow plug24when the state where the starter is not started continues after the ignition switch IG is set to ON. That is, if the ignition switch IG is set to the ON state, the energization of the glow plug24is started to warm up the combustion chamber20and to prepare for the starting. However, in some cases, the starter is not started thereafter. In such cases, the energization is stopped from the viewpoint of reduction of power consumption and evasion of overheating of the glow plug24. The energization period tp sets the upper limit period for this de-energization. The energization period ta defines the energization period after the completion of the starting. That is, it is thought that, after continuing the energization of the glow plug24to some extent after the starting, the diesel engine10is sufficiently warmed up and suitable ignitability can be maintained even without using the glow plug24. Thus, the energization period ta sets the period necessary for continuing the energization after the completion of the starting. In detail, these energization periods tp, ta are calculated with a map shown inFIG. 5that defines the relation with coolant temperature Tw. As shown inFIG. 5, the energization periods tp, ta are set shorter as the coolant temperature Tw increases.

In following Step S12, it is determined whether the coolant temperature Tw is equal to or higher than predetermined temperature THW1. This processing determines whether the energization of the glow plug24is necessary or not. That is, since the energization of the glow plug24is unnecessary when the temperature of the diesel engine10is sufficiently high, the processing determines the necessity for the energization based on the temperature state of the diesel engine10. The coolant temperature Tw is a parameter that shows the temperature state of the diesel engine10. The predetermined temperature THW1defines the boundary of the existence of the necessity of the energization of the glow plug24.

When it is determined that the coolant temperature Tw is lower than the predetermined temperature THW1in Step S12, it determines that it is necessary to raise the temperature in the combustion chamber20of the diesel engine10, and the energization process of the glow plug24is performed in Step S14. Here, based on the temperature information outputted by the temperature detection circuit53shown inFIG. 2, PWM control of the switching elements SW1-SW4may be performed. Thus, the energization amounts of the glow plugs24are operated and the temperature thereof is controlled.

If the energization process of the glow plug24is performed in Step S14, the processing shifts to Step S16. In Step S16, it is determined whether the starter (not shown) is in an ON state. As mentioned above, this processing is the setup for stopping the energization process of the glow plug24if the starter is not brought to the ON state until the energization period tp elapses after the ignition switch IG is brought to the ON state. When the starter is not in the ON state, in Step S18, it is determined whether the energization period of the glow plug24, i.e., the energization period starting when the ignition switch IG is brought to the ON state, is equal to or longer than the energization period tp.

When it is determined that the starter is in the ON state in Step S16, the processing shifts to Step S20. In Step S20, it is determined whether the energization period after the completion of the starting is equal to or longer than the energization period ta, after the starter is activated. When Step S18or Step S20makes a negative determination, the processing returns to step S12. When Step S12, Step S18or Step S20makes affirmative determination, the processing shifts to Step522. The energization of all the cylinders is ended in Step S22.

Thus, in the present embodiment, the energization is ended when the starter is not started within the energization period tp after the ignition switch IG is brought to the ON state, when the energization period ta elapses after the completion of the starting, or when the coolant temperature Tw becomes equal to or higher than the predetermined temperature THW1.

A mode of the temperature control of the glow plug24is shown inFIG. 6. As shown inFIG. 6, when the starting of the diesel engine10is performed, the energization of the glow plug24is completed when the energization period ta elapses after the completion of the starting, and then, the temperature Tg of the glow plug24falls.

When disconnection arises in the closed loop circuit connecting the glow plug24and the battery B although the switching elements SW1-SW4are in the ON states, the inside of the combustion chamber20cannot be heated by the glow plug24. Therefore, when the coolant temperature Tw is lower than the predetermined temperature THW1, lowering of the startability of the diesel engine10is a problem.

Next, processing to cope with this problem will be explained.FIG. 7shows a procedure of disconnection abnormality diagnosis processing of the glow plug24according to the present embodiment. The ECU40repeatedly performs the processing, for example, in a predetermined cycle. In a series of the processing, it is first determined in Step S30whether the energization process of the glow plug24is in progress. When S30is YES, the processing shifts to Step S32. The disconnection abnormality of the glow plug24is diagnosed in Step S32. Here, it may be determined that the disconnection occurs when the current flowing through a certain glow plug24is equal to or less than a threshold value although a corresponding one of the switching elements SW1-SW4is in the ON state. The threshold value is set at a value for avoiding erroneously determining that the current flows through the glow plug24due to an influence of a noise. In Step S34, it is determined whether there is a cylinder that has an abnormality in the glow plug24as a result of the diagnosis of Step S32. When it is determined that there is an abnormal cylinder, the processing shifts to Step S36. In Step S36, the energization of the abnormal cylinder is cut and the abnormality is reported to an outside through the display45(e.g., an abnormality lamp is lit). When negative determination is made in Step S30or Step S34, or when the processing of Step S36is completed, this series of the processing is ended once.

FIG. 8shows a procedure of processing in the case of the disconnection abnormality of the glow plug24according to the present embodiment. The ECU40repeatedly performs the processing, for example, in a predetermined cycle. The series of the processing (Step S50) performs optimum control according to the coolant temperature Tw and the number of the abnormal cylinder(s) to compensate the lowering of the startability due to the disconnection abnormality during a period since the starter is brought to the ON state (Step S40: YES) until the starting is completed (Step S42: YES).

Details of Step S50are shown inFIG. 9. Here, following four kinds of processing are selectively performed according to whether the number N of the abnormal cylinder(s) is equal to or less than a predetermined number Na (Step S51) and whether the coolant temperature Tw is equal to or higher than predetermined temperature α (Step S52, S53).

Step S54is processing performed when the number N of the abnormal cylinder(s) is equal to or less than the predetermined number Na and the coolant temperature Tw is equal to or higher than the predetermined temperature α. In particular, Step S54performs processing for cutting the fuel injection of the abnormal cylinder. There is a possibility that the temperature in the combustion chamber20of the cylinder with the disconnection abnormality of the glow plug24is too low to ignite the fuel and the fuel is not used in the combustion in the combustion chamber20. Even if the fuel is used in the combustion, there is a possibility that incomplete combustion is caused and the black lead is discharged. Therefore, in the present embodiment, useless consumption of the fuel and discharge of the black lead are avoided by stopping the injection. By stopping the injection of the fuel, further cooling of the combustion chamber20due to the fuel injection is avoided.

Step S55is processing performed when the number N of the abnormal cylinder(s) is equal to or less than the predetermined number Na and the coolant temperature Tw is lower than the predetermined temperature α. In particular, Step S55performs processing for increasing the fuel injection quantity in the normal cylinder. If there is the cylinder with the abnormality in the glow plug24, the cylinder cannot exert combustion energy. In such the case, there is a possibility that the combustion energy of the diesel engine10falls short as a whole. Specifically when the coolant temperature Tw is low, the friction among the piston18, the inner wall of the cylinder block16and the like of the diesel engine10increases. Therefore, the combustion energy tends to fall short. Therefore, the fuel injection quantity of the normal cylinder is increased under such a situation. At this time, the fuel injection of the abnormal cylinder should be preferably cut.

Step S56is processing performed when the number N of the abnormal cylinder(s) is greater than the predetermined number Na and the coolant temperature Tw is equal to or higher than the predetermined temperature α. In particular, processing for delaying the injection timing of the abnormal cylinder is performed. Thus, a compression degree of the gas in the combustion chamber20as of the injection increases, so the temperature in the combustion chamber20as of the injection can be raised. Thus, the ignitability of the fuel can be increased even in the cylinder with the abnormality in the glow plug24, so the combustion energy of the abnormal cylinder can be used for the starting. When the number N of the abnormal cylinder(s) is greater than the predetermined number Na, there is a possibility that it becomes difficult to secure the energy necessary for the starting only with the normal cylinder(s). Therefore, in the present embodiment, the ignitability in the abnormal cylinder is improved under such a situation.

Step S57is processing performed when the number N of the abnormal cylinder(s) is greater than the predetermined number Na and the coolant temperature Tw is lower than the predetermined temperature α. In particular, processing for delaying the valve timing of the intake valve14of the abnormal cylinder is performed. More preferably, processing for delaying the valve timing of the intake valves14of all the cylinders should be performed. Thus, the compression ratio of the combustion chamber(s)20of the abnormal cylinder(s) or the like can be increased, so the temperature in the combustion chamber(s)20at the time of the injection can be raised. Thus, the ignitability of the fuel can be increased even in the cylinder with the abnormality in the glow plug24, so the combustion energy of the abnormal cylinder can be used for the starting. That is, when the number N of the abnormal cylinder(s) is greater than the predetermined number Na, there is a possibility that it becomes difficult to secure the energy necessary for the starting with only the normal cylinder(s). Moreover, when the coolant temperature Tw is lower than the predetermined temperature α, there is a possibility that it becomes difficult to sufficiently improve the ignitability by delaying the injection timing. Therefore, in the present embodiment, the ignitability in the abnormal cylinder(s) is improved by delaying the valve timing under such a situation.

The above-described predetermined number Na is set according to a boundary value, at which the starting can be performed with only the normal cylinder(s). The predetermined temperature α is set lower than above-described predetermined temperature THW1. In the processing shown inFIG. 9, preferably, the processing of Step S54and S56should not be performed when the temperature Tw is higher than the predetermined temperature THW1.

The present embodiment described above exerts following effects, for example.

(1) When the abnormality in the glow plug24is detected, in order to compensate the lowering of the startability due to the abnormality, the operation mode of the actuator for the power control of the diesel engine10is changed on the occasion of the starting of the diesel engine10. Thus, the lowering of the startability due to the abnormality in the glow plug24can be compensated, and the startability can be improved.

(2) The fuel injection of the cylinder in which the abnormality of the glow plug24id detected is cut. Thus, useless consumption of the fuel and the discharge of the black lead can be avoided. By cutting the fuel injection, the further temperature decrease in the combustion chamber20of the cylinder in which the abnormality is detected can be also avoided.

(3) The correction for increasing the fuel of the cylinder in which the abnormality of the glow plug24is not detected is performed. Thus, even if the combustion energy of the fuel is not generated in the abnormal cylinder, the insufficiency in the combustion energy can be compensated with the combustion energy in other cylinder(s).

(4) When there is the abnormality in the glow plug24, the timing of the fuel injection through the injector22in the abnormal cylinder is delayed. Thus, the ignitability of the fuel in the combustion chamber20can be improved, and the startability can be improved as a result.

(5) The valve timing of the intake valve14is delayed. Thus, the ignitability of the fuel in the combustion chamber20of the abnormal cylinder can be improved, and the startability can be improved eventually.

(6) When the number of the abnormal cylinder(s) is greater than the predetermined number, processing for promoting the ignitability of the abnormal cylinder is performed. When the number is equal to or less than the predetermined number, the fuel cut of the abnormal cylinder or the injection quantity increase of the normal cylinder is performed. Thus, more suitable start control can be performed.

(7) If the number of the abnormal cylinder(s) is equal to or less than the predetermined number, the injection quantity increase of the normal cylinder is performed when the coolant temperature is lower than the predetermined temperature α and the fuel injection to the abnormal cylinder is cut when the temperature is equal to or higher than the predetermined temperature α. Thus, further more suitable start control can be performed.

(8) If the number of the abnormal cylinder(s) is greater than the predetermined number, the valve timing of the intake valve14is delayed when the coolant temperature is lower than the predetermined temperature α and the injection timing is delayed when the temperature is equal to or higher than the predetermined temperature α. Thus, still more suitable start control can be performed.

Next, a second embodiment of the present invention will be described with reference to the drawings, focusing on the differences from the first embodiment.

FIG. 10shows a procedure of the power control accompanying the starting of the diesel engine10according to the present embodiment. The ECU40repeatedly performs the processing, for example, in a predetermined cycle. As shown inFIG. 10, in the present embodiment, it is determined whether the operation state of the diesel engine10is stabilized after the completion of the starting (Step S44). Whether the operation state of the diesel engine10is stabilized may be determined based on whether a rotation fluctuation amount of the crankshaft26becomes equal to or lower than a predetermined value, for example. If the diesel engine10has a cylinder pressure sensor for sensing the pressure in the combustion chamber20, the ignition timing may be sensed based on the sensing value and the stability of the operation state (i.e., stability of combustion) may be determined based on the ignition timing. It is thought that the ignitability in the cylinder with the abnormality in the glow plug24is low while the operation state of the diesel engine10is unstable. Therefore, in the present embodiment, processing of Step S60is performed under such a situation.

FIG. 11shows the details of the processing of Step S60. As shown inFIG. 11, when the number N of the abnormal cylinder(s) is equal to or less than the predetermined number Na (Step S61: YES), processing for increasing the injection quantity of the normal cylinder is performed in Step S65like Step S55ofFIG. 9. When the number N of the abnormal cylinder(s) is greater than the predetermined number Na (Step S61: NO), it is determined whether the coolant temperature Tw is equal to or higher than the predetermined temperature α in Step S63. When the coolant temperature Tw is equal to or higher than the predetermined temperature α, the same processing as Step S56ofFIG. 9is performed in Step S66. When the coolant temperature Tw is lower than the predetermined temperature α, the same processing as Step S57ofFIG. 9is performed in Step S67.

According to the above-described present embodiment, following effects are further exerted in addition to the effects (1)-(8) of the first embodiment.

(9) The operation mode of the actuator of the diesel engine10is changed to compensate the instability of the operation state of the diesel engine10due to the abnormality in the glow plug24after the completion of the starting of the diesel engine10. Thus, the instability due to the abnormality can be inhibited or avoided suitably.

(10) The correction for increasing the fuel of the cylinder, in which no abnormality is detected, is performed to stabilize the operation state of the diesel engine10after the completion of the starting. Thus, the shortage of the combustion energy can be suitably inhibited or averted.

(11) The timing of the fuel injection through the injector22is delayed to stabilize the operation state of the diesel engine10after the completion of the starting. Thus, the ignitability of the fuel in the combustion chamber20can be improved.

(12) The valve timing of the intake valve14is delayed to stabilize the operation state of the diesel engine10after the completion of the starting. Thus, the ignitability of the fuel in the combustion chamber20can be improved.

(13) The control for stabilizing the operation state is switched according to whether the number of the abnormal cylinder(s) is equal to or less than the predetermined number and according to whether the coolant temperature is equal to or higher than the predetermined temperature α. Thus, the operation state of the diesel engine10can be stabilized more appropriately.

The above-described embodiments may be modified as follows for example.

In the above-described first or second embodiment, the four kinds of processing in Steps S54to S57ofFIG. 9may be used together as processing from the starter ON state to the completion of the starting. That is, for example, according to the situation, the processing for delaying the valve timing may be used in combination with the processing for increasing the fuel injection quantity of the normal cylinder. For example, according to the situation, the processing for delaying the injection timing of the abnormal cylinder may be used in combination with the processing for increasing the fuel injection quantity of the normal cylinder. For example, according to the situation, the processing for delaying the injection timing of the abnormal cylinder may be used in combination with the processing for delaying the valve timing of the abnormal cylinder. Moreover, for example, according to the situation, the processing for delaying the injection timing of the abnormal cylinder, the processing for delaying the valve timing of the abnormal cylinder and the processing for increasing the injection quantity of the normal cylinder may be used in combination.

In the above-described second embodiment, the three kinds of the processing in Steps S65to S67ofFIG. 11may be used together as processing since the starting is completed until the operation state is stabilized. That is, for example, according to the situation, the processing for delaying the valve timing may be used in combination with the processing for increasing the fuel injection quantity of the normal cylinder. For example, according to the situation, the processing for delaying the injection timing of the abnormal cylinder may be used in combination with the processing for increasing the fuel injection quantity of the normal cylinder. For example, according to the situation, the processing for delaying the injection timing of the abnormal cylinder may be used in combination with the processing for delaying the valve timing of the abnormal cylinder. Moreover, for example, according to the situation, the processing for delaying the injection timing of the abnormal cylinder the processing for delaying the valve timing of the abnormal cylinder and the processing for increasing the injection quantity of the normal cylinder may be used in combination.

The parameter for grasping the temperature state of the diesel engine10is not limited to the coolant temperature. For example, temperature of engine oil circulating through the diesel engine10may be used.

The scheme for increasing the temperature in the combustion chamber20is not limited to the above-mentioned scheme. For example, the temperature in the combustion chamber20may be increased by reducing the air quantity flowing into the combustion chamber20compared with the case where the air quantity is not reduced.

The valve characteristic varying device is not limited to the variable valve timing device36mentioned above. For example, a device for varying a lift amount of the valve may be used. Also in this case, the compression ratio can be increased by changing the valve characteristic, so the ignitability can be improved.

In the above-described embodiments, the processing suitably selected from multiple types of processing according to the situation is used as the processing for compensating the lowering of the startability or the instability of the operation state in the case of the abnormality of the glow plug24. However, the invention is not limited to this. For example, useless fuel consumption can be avoided by cutting the fuel injection of the abnormal cylinder when the disconnection abnormality of the glow plug24is detected. For example, the shortage of the combustion energy can be compensated by increasing the fuel injection quantity of the normal cylinder when the disconnection abnormality of the glow plug24is detected. For example, the ignitability of the abnormal cylinder can be improved by delaying the injection timing when the disconnection abnormality of the glow plug24is detected. Furthermore, for example, the ignitability of the abnormal cylinder can be improved by delaying the valve timing when the disconnection abnormality of the glow plug24is detected.

The changing scheme for changing the operation mode of the actuator of the diesel engine10to control the state quantity in the combustion chamber20of the diesel engine10such that the lowering of the startability due to the disconnection abnormality of the glow plug24is compensated is not limited to the scheme illustrated in each of the above-described embodiments. For example, output torque may be increased by advancing the injection timing of the normal cylinder.

The acquisition method of the temperature information of the glow plug24is not limited to the method illustrated in each of the above-described embodiments. For example, the temperature of the glow plug24may be directly measured using a temperature sensor. The diagnosis method of the disconnection abnormality of the glow plug24is not limited to the method illustrated in each of the above-described embodiments. For example, the method described in Patent Document 1 may be used.

The diesel engine is not limited to the four-cylinder engine. The ignitability of the fuel becomes problematic specifically when the starting is performed in a low-temperature state not only in the diesel engine but also in a compression ignition type internal combustion engine. The compression ignition type internal combustion engine ignites the fuel, which is injected into the combustion chamber, by compression. Therefore, the present invention is specifically effective for the compression ignition type internal combustion engine. Not only in the case of the compression ignition type internal combustion engine but also in the case of a spark ignition type internal combustion engine such as a gasoline engine, if the engine has a heat generating unit projecting into the combustion chamber for compensating the lowering of the ignitability of fuel as of the starting in the low-temperature state, the application of the present invention is effective in the case of the abnormality of the heat generating unit.