Patent Application
20080208440
This application is based on and incorporates herein by reference Japanese Patent Application No. 2006-301053 filed on Nov. 7, 2006.
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.
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.
Features and advantages of embodiments will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings:
Referring to
If the fuel is injected into the combustion chamber 20, the fuel causes self-ignition due to compression of the combustion chamber 20, and energy is generated. The energy is taken out as rotational energy of an output shaft (crankshaft 26) of the diesel engine 10 through the piston 18. A crank angle sensor 28 for sensing a rotation angle of the crankshaft 26 is provided near the crankshaft 26. A coolant flows through the cylinder block 16 to suppress the temperature increase of the diesel engine 10 due to the combustion of the fuel. A coolant temperature sensor 30 for sensing the temperature of the coolant is provided to the cylinder block 16.
After the fuel is injected into the combustion chamber 20 through the injector 22 and the combustion arises, a gas used in the combustion is discharged to an exhaust passage 32 as exhaust gas through an opening operation of an exhaust valve 31.
The opening and closing drive of both the above-described intake valve 14 and the exhaust valve 31 is performed by the torque of the crankshaft 26. Specifically, a variable valve timing device 36 that varies a rotation phase difference of an intake side camshaft 34 with respect to the crankshaft 26 is provided to the intake valve 14. A cam angle sensor 37 for sensing a rotation angle of the intake side camshaft 34 is provided near the intake side camshaft 34.
An electronic control unit (ECU 40) operates the various actuators such as the injector 22 based on the sensing values of the various sensors sensing the operation states of the diesel engine 10 and requests of a user. Thus, the ECU 40 controls output characteristics (output torque, exhaust characteristic) of the diesel engine 10. Specifically the ECU 40 operates a temperature state of the glow plug 24 through a controller 50. Furthermore, the ECU 40 performs abnormality diagnosis of the glow plug 24 through the controller 50 and outputs the result on a display 45 when the abnormality arises.
Resistors R1-R4 are connected to the glow plugs 24 of the respective cylinders in parallel. Quantities of voltage drops due to the resistors R1-R4 are taken into a current detection circuit 52. The current detection circuit 52 detects quantity of current flowing through each glow plug 24 of each cylinder based on the quantity of the voltage drop. These sensing results are outputted to a temperature detection circuit 53 and a disconnection detection circuit 54.
The temperature detection circuit 53 indirectly senses the temperature Tg of the glow plug 24 of each cylinder based on the current which flows through the glow plug 24 of the cylinder. That is, since the resistance R of the glow plug 24 has temperature dependency as shown in
The disconnection detection circuit 54 detects an existence or nonexistence of a disconnection abnormality in a closed loop circuit including the glow plug 24 based on whether the current flows through the glow plug 24 of each cylinder. The detection result of the existence or nonexistence of the disconnection abnormality is outputted to the ECU 40 as diagnostic information through the control circuit 51.
The ECU 40 takes in the signal about the temperature of the glow plug 24, the output signal of the coolant temperature sensor 30, and also the voltage value of the battery B. The ECU 40 changes these into digital data with an A/D converter 41. The digital data outputted by the A/D converter 41 is taken into a microcomputer 42. The microcomputer 42 generates the above-described command signal based on these input data, and outputs the command signal to the controller 50 through an output circuit 43. The diagnostic information outputted by the controller 50 and the state of the ignition switch IG are taken into the microcomputer 42 through an input circuit 44.
A procedure of the energization processing applied to the glow plug 24 is shown in
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 plug 24 is necessary or not. That is, since the energization of the glow plug 24 is unnecessary when the temperature of the diesel engine 10 is sufficiently high, the processing determines the necessity for the energization based on the temperature state of the diesel engine 10. The coolant temperature Tw is a parameter that shows the temperature state of the diesel engine 10. The predetermined temperature THW1 defines the boundary of the existence of the necessity of the energization of the glow plug 24.
When it is determined that the coolant temperature Tw is lower than the predetermined temperature THW1 in Step S12, it determines that it is necessary to raise the temperature in the combustion chamber 20 of the diesel engine 10, and the energization process of the glow plug 24 is performed in Step S14. Here, based on the temperature information outputted by the temperature detection circuit 53 shown in
If the energization process of the glow plug 24 is 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 plug 24 if 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 plug 24, 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 S18 or Step S20 makes a negative determination, the processing returns to step S12. When Step S12, Step S18 or Step S20 makes affirmative determination, the processing shifts to Step 522. 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 plug 24 is shown in
When disconnection arises in the closed loop circuit connecting the glow plug 24 and the battery B although the switching elements SW1-SW4 are in the ON states, the inside of the combustion chamber 20 cannot be heated by the glow plug 24. Therefore, when the coolant temperature Tw is lower than the predetermined temperature THW1, lowering of the startability of the diesel engine 10 is a problem.
Next, processing to cope with this problem will be explained.
Details of Step S50 are shown in
Step S54 is 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 S54 performs processing for cutting the fuel injection of the abnormal cylinder. There is a possibility that the temperature in the combustion chamber 20 of the cylinder with the disconnection abnormality of the glow plug 24 is too low to ignite the fuel and the fuel is not used in the combustion in the combustion chamber 20. 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 chamber 20 due to the fuel injection is avoided.
Step S55 is 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 S55 performs processing for increasing the fuel injection quantity in the normal cylinder. If there is the cylinder with the abnormality in the glow plug 24, the cylinder cannot exert combustion energy. In such the case, there is a possibility that the combustion energy of the diesel engine 10 falls short as a whole. Specifically when the coolant temperature Tw is low, the friction among the piston 18, the inner wall of the cylinder block 16 and the like of the diesel engine 10 increases. 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 S56 is 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 chamber 20 as of the injection increases, so the temperature in the combustion chamber 20 as 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 plug 24, 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 S57 is 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 valve 14 of the abnormal cylinder is performed. More preferably, processing for delaying the valve timing of the intake valves 14 of all the cylinders should be performed. Thus, the compression ratio of the combustion chamber(s) 20 of the abnormal cylinder(s) or the like can be increased, so the temperature in the combustion chamber(s) 20 at 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 plug 24, 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 in
The present embodiment described above exerts following effects, for example.
(1) When the abnormality in the glow plug 24 is 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 engine 10 is changed on the occasion of the starting of the diesel engine 10. Thus, the lowering of the startability due to the abnormality in the glow plug 24 can be compensated, and the startability can be improved.
(2) The fuel injection of the cylinder in which the abnormality of the glow plug 24 id 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 chamber 20 of 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 plug 24 is 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 plug 24, the timing of the fuel injection through the injector 22 in the abnormal cylinder is delayed. Thus, the ignitability of the fuel in the combustion chamber 20 can be improved, and the startability can be improved as a result.
(5) The valve timing of the intake valve 14 is delayed. Thus, the ignitability of the fuel in the combustion chamber 20 of 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 valve 14 is 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.
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 engine 10 is changed to compensate the instability of the operation state of the diesel engine 10 due to the abnormality in the glow plug 24 after the completion of the starting of the diesel engine 10. 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 engine 10 after 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 injector 22 is delayed to stabilize the operation state of the diesel engine 10 after the completion of the starting. Thus, the ignitability of the fuel in the combustion chamber 20 can be improved.
(12) The valve timing of the intake valve 14 is delayed to stabilize the operation state of the diesel engine 10 after the completion of the starting. Thus, the ignitability of the fuel in the combustion chamber 20 can 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 engine 10 can 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 S54 to S57 of
In the above-described second embodiment, the three kinds of the processing in Steps S65 to S67 of
The parameter for grasping the temperature state of the diesel engine 10 is not limited to the coolant temperature. For example, temperature of engine oil circulating through the diesel engine 10 may be used.
The scheme for increasing the temperature in the combustion chamber 20 is not limited to the above-mentioned scheme. For example, the temperature in the combustion chamber 20 may be increased by reducing the air quantity flowing into the combustion chamber 20 compared with the case where the air quantity is not reduced.
The valve characteristic varying device is not limited to the variable valve timing device 36 mentioned 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 plug 24. 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 plug 24 is 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 plug 24 is detected. For example, the ignitability of the abnormal cylinder can be improved by delaying the injection timing when the disconnection abnormality of the glow plug 24 is 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 plug 24 is detected.
The changing scheme for changing the operation mode of the actuator of the diesel engine 10 to control the state quantity in the combustion chamber 20 of the diesel engine 10 such that the lowering of the startability due to the disconnection abnormality of the glow plug 24 is 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 plug 24 is not limited to the method illustrated in each of the above-described embodiments. For example, the temperature of the glow plug 24 may be directly measured using a temperature sensor. The diagnosis method of the disconnection abnormality of the glow plug 24 is 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.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-301053 | Nov 2006 | JP | national |
