JP4882914B2 - Operation control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine, and more particularly to suppressing opening of a mouth generated between a cylinder head and a cylinder block.

  A so-called reciprocating internal combustion engine in which a piston reciprocates in a cylinder is configured by fastening a cylinder head and a cylinder block. In such an internal combustion engine, a gasket is interposed between the cylinder head and the cylinder block so as to be surrounded by the cylinder head, the cylinder inner surface, and the piston, thereby ensuring airtightness in a space where the air-fuel mixture burns. In such an internal combustion engine, for example, Patent Document 1 discloses a technique for retarding the ignition timing of the internal combustion engine in order to warm up the catalyst at the time of cold start.

Japanese Patent Laid-Open No. 2004-116310 FIG.

  By the way, after the cold start of the internal combustion engine, for example, when the operating conditions are such that the accelerator opening is high and the internal combustion engine generates a high output, the internal combustion engine is rapidly warmed up immediately after the cold start. In this case, the temperature rise inside the cylinder is abrupt, but the temperature rise outside the cylinder is moderate. As a result, the thermal expansion inside the cylinder becomes larger than the thermal expansion outside, and the cylinder block and the cylinder head There may be a gap called a mouth opening. The technique disclosed in Patent Document 1 does not consider this point, and there is room for improvement.

  The present invention has been made in view of the above, and an object of the present invention is to suppress opening of a mouth generated between a cylinder block and a cylinder head of an internal combustion engine.

In order to solve the above-described problems and achieve the object, an operation control device for an internal combustion engine according to the present invention includes a generated heat amount calculation unit that obtains a parameter related to the amount of heat generated by the internal combustion engine, and the internal combustion engine based on the parameter. Obtaining an opening allowable temperature threshold for determining the possibility of an unacceptable opening between the cylinder head and the cylinder block of the engine, and acquiring the temperature of the cooling medium for cooling the internal combustion engine A control condition determination unit that compares the temperature of the cooling medium with the opening allowable temperature threshold, and when the temperature of the cooling medium is equal to or lower than the opening allowable temperature threshold, the temperature of the cooling medium increases. And a mouth opening suppression unit that increases the speed from the current time. As a result, the operation control apparatus for an internal combustion engine according to the present invention can suppress the opening between the cylinder block and the cylinder head of the internal combustion engine.

  As a desirable mode of the present invention, in the operation control device of the internal combustion engine, it is preferable that the opening suppression unit raises the temperature of the exhaust gas discharged from the internal combustion engine from the present time.

  As a desirable aspect of the present invention, in the operation control apparatus for an internal combustion engine, the opening suppression unit may raise the temperature of the exhaust gas by retarding the ignition timing of the internal combustion engine from the current time. preferable.

  As a desirable aspect of the present invention, in the operation control apparatus for an internal combustion engine, it is preferable that an integrated value of the parameter integrated from the start of the internal combustion engine is used as the parameter related to the amount of heat generated by the internal combustion engine.

  As a desirable aspect of the present invention, in the operation control apparatus for an internal combustion engine, as a parameter relating to the amount of heat generated by the internal combustion engine, an intake air amount of the internal combustion engine, a fuel injection amount of the internal combustion engine, or an output of the internal combustion engine Alternatively, it is preferable to use at least one integrated value of the accelerator opening of the internal combustion engine.

  The present invention can suppress the opening between the cylinder block and the cylinder head of the internal combustion engine.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. In the following, a spark ignition type internal combustion engine will be described as an example, but the application target of the present invention is not limited to this, and can be applied to a so-called diesel engine.

  In the present embodiment, an opening allowable temperature threshold for determining whether an unacceptable opening may occur between the cylinder head and the cylinder block of the internal combustion engine is compared with the temperature of the cooling medium that cools the internal combustion engine. However, when the temperature of the cooling medium is equal to or lower than the temperature threshold, the temperature of the exhaust gas discharged from the internal combustion engine is increased. Here, the opening allowable temperature threshold is a value obtained based on a parameter relating to the amount of heat generated by the internal combustion engine, and is a function of the parameter. Here, the control for suppressing the opening between the cylinder head and the cylinder block of the internal combustion engine is referred to as opening control.

  FIG. 1 is a schematic configuration diagram of an internal combustion engine and an operation control device for the internal combustion engine according to the present embodiment. The internal combustion engine 1 is a so-called reciprocating internal combustion engine in which a piston 4 reciprocates in a cylinder 1S. The operation of the internal combustion engine 1 is controlled by an engine ECU (Electronic Control Unit) 50 that functions as an operation control device (hereinafter referred to as an operation control device) for the internal combustion engine according to the present embodiment. The internal combustion engine 1 includes a plurality of cylinders 1S. For example, four cylinders 1S are arranged in series. In the present embodiment, the number and arrangement of the cylinders 1S are not limited to in-line four cylinders.

  The internal combustion engine 1 includes a cylinder block 3, a cylinder head 2 that is fastened to and integrated with the cylinder block 3, a piston 4 that reciprocates in the cylinder 1 </ b> S, a crankshaft 6, a piston 4, and a crankshaft 6. A connecting rod 5 to be connected and a spark plug 8 provided in the cylinder 1S are provided.

  The cylinder block 3 is provided with a cylinder-side water jacket 3W. The cylinder-side water jacket 3W is a passage through which a cooling medium for cooling the internal combustion engine 1 (water in the present embodiment, hereinafter referred to as cooling water) flows. The cylinder head 2 is provided with a head-side water jacket 2W. The head-side water jacket 2W is a passage through which cooling water for cooling the internal combustion engine 1 flows.

  An in-cylinder combustion part B surrounded by the piston 4, the cylinder block 3, and the cylinder head 2 is formed in the cylinder 1 </ b> S provided in the internal combustion engine 1. In the in-cylinder combustion part B of the cylinder 1S, an intake port 10I connected to the intake passage 11I and an exhaust port 10E connected to the exhaust gas passage 11E are formed. The intake port 10I and the exhaust port 10E are formed in the cylinder head 2. In the in-cylinder combustion section B, the air-fuel mixture of fuel F and air A burns, and the piston 4 reciprocates in the cylinder 1S by the combustion pressure of the air-fuel mixture.

  The piston 4 is rotatably attached to the connecting rod 5, and the connecting rod 5 is rotatably attached to the crankshaft 6. As a result, the piston 4 is connected to the crankshaft 6 via the connecting rod 5. In the internal combustion engine 1, the piston 4 is reciprocated in the cylinder block 3 by burning the air-fuel mixture of the air A and the fuel F in the in-cylinder combustion section B of the cylinder 1 </ b> S. Convert to rotational motion and output.

  In the internal combustion engine 1 according to the present embodiment, the fuel injection valve 15 is disposed in the intake port 10I provided for each cylinder 1S, and the fuel F is injected from the fuel injection valve 15 into the intake port 10I. The fuel injection valve 15 injects the fuel F pressurized by the fuel pump 17 into the intake port 10I. Fuel injection control related to the fuel injection amount of the fuel injection valve 15 (that is, the fuel supply amount of the fuel F supplied to the internal combustion engine 1), the injection timing, and the like is executed by the engine ECU 50 that is an operation control device.

  As described above, the internal combustion engine 1 according to the present embodiment is supplied with the fuel F in a so-called port injection mode in which the fuel F is injected into the intake port 10I. In the present embodiment, the fuel F may be supplied to the internal combustion engine 1 by a so-called direct injection type in which the fuel F is directly injected from the fuel injection valve into the in-cylinder combustion portion B of the internal combustion engine 1. .

  A spark plug 8 is attached to a cylinder head 2 provided in the internal combustion engine 1. The electrode 8S of the spark plug 8 protrudes into the in-cylinder combustion part B of the cylinder 1S. Further, a direct ignition 8DI is attached to the spark plug 8. The direct ignition 8DI discharges the spark plug 8 by an ignition signal from the engine ECU 50, and ignites the mixed gas in the in-cylinder combustion part B of the cylinder 1S. As a result, the air-fuel mixture burns to become high-temperature and high-pressure combustion gas, and drives the piston 4. Here, the ignition operation relating to the discharge timing of the spark plug 8 is controlled by the engine ECU 50.

  An intake valve 7I is disposed in an intake side opening provided between the intake port 10I and the in-cylinder combustion part B, and an exhaust valve 7E is provided in an exhaust side opening provided between the exhaust port 10E and the in-cylinder combustion part B. Is placed. The intake valve 7I opens and closes at a predetermined timing, and when the intake valve 7I is opened, an air-fuel mixture of fuel F and air A is introduced from the intake port 10I to the in-cylinder combustion section B. The exhaust valve 7E opens and closes at a predetermined timing, and when the exhaust valve 7E is opened, combustion gas is discharged from the in-cylinder combustion section B to the exhaust port 10E.

  The intake passage 11I of the internal combustion engine 1 sucks air A in the atmosphere and introduces the sucked air A into the in-cylinder combustion part B through the intake port 10I. An air cleaner 12 is provided in the intake passage 11I, and dust, dust and the like are removed from the air A introduced into the in-cylinder combustion section B. An air flow sensor 42 is attached to the intake passage 11I, and the flow rate of the air A introduced into the in-cylinder combustion section B is detected. This flow rate is a mass flow rate. The flow rate of the air A detected by the air flow sensor 42 is taken into the engine ECU 50 and used for controlling the internal combustion engine 1.

  The intake passage 11I is provided with a throttle valve 13 that functions as intake air amount adjusting means for adjusting the flow rate (intake air amount) of air A supplied to the in-cylinder combustion section B. The throttle valve 13 is opened and closed by an actuator 13a such as a stepping motor. The opening degree of the throttle valve 13 is controlled by the engine ECU 50 adjusting the opening degree of the throttle valve 13 by the actuator 13a.

  The exhaust gas passage 11E of the internal combustion engine 1 is connected to the exhaust port 10E, and the combustion gas after combustion in the in-cylinder combustion section B and driving the piston 4 is discharged as exhaust gas Ex. An exhaust gas purification catalyst 14 is provided in the exhaust gas passage 11E. The exhaust gas purification catalyst 14 purifies nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC) contained in the exhaust gas Ex passing through the exhaust gas passage 11E. The exhaust gas Ex after being purified by the exhaust gas purification catalyst 14 is exhausted into the atmosphere through a silencer.

  Various input signals are input to the engine ECU 50 from sensors attached to various parts of the vehicle in order to control and operate the internal combustion engine 1. The input signal input to the engine ECU 50 includes, for example, the opening of the accelerator 40P (accelerator opening) detected by the accelerator opening sensor 40, the intake air amount detected by the airflow sensor 42, and the cooling water temperature sensor 41. The detected coolant temperature, the opening / closing of the thermostat detected by the thermostat opening / closing detection sensor 43, and the like.

  The engine ECU 50 controls the operation of the internal combustion engine 1 based on various maps such as the above-described input signal and a map describing the fuel injection amount stored in the storage unit 53 and a map describing the ignition timing. A control signal is output to the fuel injection valve 15, the direct ignition 8DI, and the like to be controlled. Examples of control signals that the engine ECU 50 outputs to execute operation control of the internal combustion engine 1 include a fuel injection signal that controls fuel injection of the fuel injection valve 15, an ignition signal that controls ignition of the spark plug 8, and a throttle valve There are 13 valve opening signals for controlling the valve opening.

  The engine ECU 50 includes an input / output unit (I / O) 51 that inputs and outputs the above-described input signal and output signal, a processing unit 52, and a storage unit 53 that stores various maps such as a fuel injection amount map. . The processing unit 52 includes, for example, a memory and a CPU (Central Processing Unit). The processing unit 52 includes a generated heat amount calculating unit 54 that is a generated heat amount calculating unit that obtains the amount of heat generated by the internal combustion engine 1, a control condition determining unit 55 that is a control condition determining unit, and the cylinder head 2 and the cylinder block 3. And a mouth opening restraining unit 56 that serves as a mouth opening restraining means for restraining the mouth opening. These control the operation of the internal combustion engine according to the present embodiment.

  Thus, since engine ECU50 is comprised including the means to perform the operation control of the internal combustion engine which concerns on this embodiment, engine ECU50 functions as the operation control apparatus of the internal combustion engine which concerns on this embodiment. The storage unit 53 is a non-volatile memory such as a flash memory, a memory that can only be read such as a ROM (Read Only Memory), a memory that can be read and written such as a RAM (Random Access Memory), or these. It can comprise by the combination of these.

  FIG. 2 is a schematic diagram showing a cooling system of the internal combustion engine according to the present embodiment. Cooling water for cooling the internal combustion engine 1 is discharged by a water pump 24 which is a cooling medium supply means, and circulates through a cooling system (hereinafter referred to as an engine cooling system) 20 of the internal combustion engine. The cooling water discharged from the water pump 24 cools the internal combustion engine 1 in the order of the cylinder block 3 and the cylinder head 2 of the internal combustion engine 1 and is collected by the rear joint 25, and then guided to the water outlet 23. A reservoir tank 26 is connected to the water outlet 23 and absorbs excess cooling water.

  A thermostat 22 is attached to the water outlet 23. The thermostat 22 is provided at a portion where the cooling water sent from the radiator 21 is introduced into the water outlet 23. When the cooling water temperature is lower than a predetermined temperature, for example, when it is lower than the temperature when the internal combustion engine 1 is warmed up, the thermostat 22 is closed, so that the cooling water that has passed through the radiator 21 passes through the water outlet 23. Does not flow into. In this case, the cooling water collected from the rear joint 25 to the water outlet 23 does not pass through the radiator 21 but is sucked into the water pump 24 and supplied to the internal combustion engine 1 again. By not guiding the cooling water to the radiator 21, the temperature of the cooling water is raised early, and the warm-up of the internal combustion engine 1 is completed early.

  When the cooling water temperature is higher than a predetermined temperature, for example, higher than the warm-up completion temperature of the internal combustion engine 1, the thermostat 22 is opened. As a result, the cooling water collected in the water outlet 23 passes through the radiator 21 and then flows into the water outlet 23 through the thermostat 22. The cooling water that has passed through the radiator 21 is cooled by exchanging heat with the outside air while passing through the radiator 21, then flows into the water outlet 23, and is then sucked into the water pump 24 and supplied to the internal combustion engine 1 again. Is done. Thus, after the warm-up of the internal combustion engine 1 is completed, the cooling water is actively cooled by flowing the cooling water to the radiator 21 to avoid overheating of the internal combustion engine 1.

  FIG. 3 is an enlarged view showing a connecting portion between the cylinder head and the cylinder block of the internal combustion engine according to the present embodiment. As shown in FIG. 3, a gasket 16 is provided between the cylinder head 2 and the cylinder block 3 of the internal combustion engine 1. Thereby, the airtightness of the in-cylinder combustion part B and the watertightness between the cylinder side water jacket 3W and the head side water jacket 2W are ensured.

  4 and 5 are conceptual diagrams for explaining the opening phenomenon in which the cylinder head and the cylinder block are opened. FIG. 6 is a conceptual diagram showing the relationship between the inner wall temperature of the cylinder and the outer temperature of the cylinder and the coolant temperature when the internal combustion engine is operated at a high output immediately after the cold start. FIG. 7 is a conceptual diagram showing the relationship between the opening amount and the temperature difference between the inner wall temperature of the cylinder and the outer temperature of the cylinder. FIG. 8 is a conceptual diagram showing an opening determination map used for opening suppression control according to the present embodiment. FIG. 9 is a schematic diagram illustrating an example of a temporal change in the opening amount.

  During the operation of the internal combustion engine 1, the internal combustion engine 1 is cooled by flowing cooling water to the cylinder side water jacket 3 </ b> W and the head side water jacket 2 </ b> W so that the internal combustion engine 1 is not excessively heated. FIG. 4 shows that when the internal combustion engine 1 is gradually warmed up before the warming up of the internal combustion engine 1 is completed, that is, the temperature of the cylinder inner wall 3B and the temperature of the cylinder outer side 3A of the cylinder block 3 gradually increase. Shows the case. In this case, since the temperature increase rate is about the same between the inside and outside of the cylinder-side water jacket 3W, the thermal expansion rate between the inside and outside of the cylinder-side water jacket 3W is about the same. As a result, the position of the end (inner end) 3Ti inside the cylinder-side water jacket 3W and the position of the end (outer end) 3Te outside the cylinder-side water jacket 3W change in the same manner.

  FIG. 5 shows a state in which the internal combustion engine 1 is operated at a high output immediately after the cold start of the internal combustion engine 1, for example, by fully opening the accelerator 40P shown in FIG. Results are shown. FIG. 6 shows the inner wall temperature Ti and the outer temperature To with respect to the change in the cooling water temperature Tw, but the cooling water temperature Tw increases as the operating time of the internal combustion engine 1 elapses. The time change of Ti and the outside temperature To will be shown. When the internal combustion engine 1 is operated at a high output immediately after the cold start of the internal combustion engine 1, as shown in FIG. 6, the temperature (inner wall temperature) Ti of the cylinder inner wall 3B rapidly increases, but the temperature of the cylinder outer 3A ( The rise in the outer temperature To becomes slower than the rise in the temperature of the cylinder inner wall 3B.

  When a difference occurs between the rising speed of the inner wall temperature Ti and the rising speed of the outer temperature To, a temperature difference between the inner wall temperature Ti and the outer temperature To occurs, and the rising speed of the inner wall temperature Ti and the rising speed of the outer temperature To As the difference increases, the temperature difference between the inner wall temperature Ti and the outer temperature To increases. As a result, the amount of thermal expansion inside the cylinder-side water jacket 3W becomes larger than the amount of thermal expansion outside, and the inner end 3Ti protrudes toward the cylinder head 2 from the outer end 3Te. As a result, a mouth opening occurs between the cylinder block 3 and the cylinder head 2. In other words, the opening is a gap formed between the cylinder block 3 and the cylinder head 2, and the size C of the gap is the opening amount.

  When the mouth opening occurs, cooling water may leak from the cylinder-side water jacket 3W or the head-side water jacket 2W, or lubricating oil that lubricates the valve operating system may leak from the cylinder head 2, so that the mouth opening is suppressed. There is a need. As shown in FIG. 7, when the internal combustion engine 1 is operated at a high output immediately after the cold start (that is, when the amount of heat generated by the internal combustion engine 1 is large), the opening amount C is determined by the inner wall temperature Ti and the outer temperature. The temperature difference from To (the temperature difference between inside and outside the cylinder) ΔT increases as it increases. Here, as shown in FIG. 6, since the inner wall temperature Ti and the outer temperature To have a high correlation with the cooling water temperature Tw, the cylinder internal / external temperature difference ΔT can be estimated from the cooling water temperature Tw. That is, the opening amount C can be estimated from the cooling water temperature Tw.

  Changes in the outside temperature To, the cooling water temperature Tw, and the cooling water temperature Tw when the internal combustion engine is operated at a high output immediately after the cold start are transient, and these temperature changes are generated by the internal combustion engine 1. It depends on the amount of heat. Therefore, when the internal combustion engine is operated at a high output immediately after the cold start, if the amount of heat generated by the internal combustion engine 1 changes depending on the operating conditions of the internal combustion engine 1, the inner wall temperature Ti, the outer temperature To, and the cooling water temperature Tw The relationship also changes. That is, the opening amount C changes depending on the amount of heat generated by the internal combustion engine 1.

  In this embodiment, when suppressing the opening, the amount of heat generated by the internal combustion engine 1 is taken into consideration, and a cooling water temperature at which an unacceptable opening is likely to occur is obtained, and based on this cooling water temperature, it is not allowable. Determine the possibility of mouth opening. In the present embodiment, when the amount of heat generated by the internal combustion engine 1 is taken into consideration, an integrated value of the amount of heat generated by the internal combustion engine 1 (generated heat amount integrated value) is used as a parameter relating to the amount of heat generated by the internal combustion engine.

  The mouth opening determination map 60 shown in FIG. 8 is a cooling water temperature (open mouth allowable temperature) for determining the possibility of an unacceptable opening in the relationship between the cooling water temperature Tw and the generated heat amount integrated value ΣW. Threshold) Twc is described. The mouth opening allowable temperature threshold value Twc is expressed as a function of the generated heat amount integrated value ΣW. That is, Twc = f (ΣW). The generated heat amount integrated value ΣW is the amount of heat generated by the internal combustion engine 1 after the cold start of the internal combustion engine 1 until it is determined that an unacceptable opening of the mouth may occur. As described above, by using the generated heat amount integrated value ΣW, it is possible to accurately estimate the history of heat generation of the internal combustion engine 1 from the cold start of the internal combustion engine 1 until it is determined that an unacceptable opening of the mouth may occur. As a result, the accuracy of determining the possibility of unacceptable mouth opening is improved.

  When it is determined in the mouth opening suppression control according to the present embodiment that there is a possibility that unacceptable mouth opening occurs, the coolant temperature Tw at that time is obtained, the generated heat amount integrated value ΣW of the internal combustion engine 1 is obtained, and both of them are entered. This is given to the opening determination map 60.

  As a result, when the cooling water temperature Tw with respect to the generated heat amount integrated value ΣW at the time of the determination is equal to or less than the opening allowable temperature threshold value Twc, the temperature rise of the cooling water is small with respect to the heat amount generated by the internal combustion engine 1. . That is, the temperature inside the cylinder-side water jacket 3W rapidly rises, but the heat receiving from the inner wall side of the cylinder to the cooling water is delayed due to the heat capacity. It can be estimated that the temperature rise is small. In this case, it can be determined that the inner wall temperature Ti has a higher temperature rise than the outer temperature To, and the risk of unacceptable opening is high.

  On the other hand, when the coolant temperature Tw with respect to the generated heat amount integrated value ΣW at the time of the determination is higher than the opening allowable temperature threshold value Twc, the temperature rise of the coolant with respect to the heat amount generated by the internal combustion engine 1 is appropriate. That is, as a result of appropriate heat reception from the inner wall side of the cylinder to the cooling water, it can be estimated that the temperature increases similarly on the inside and outside of the cylinder-side water jacket 3W. For this reason, since the rising speeds of the inner wall temperature Ti and the outer temperature To are approximately the same, it can be determined that no unacceptable opening occurs.

  Here, the generated heat amount integrated value ΣW correlates with the temperature inside the cylinder-side water jacket 3W (ie, the inner wall temperature Ti), and the cooling water temperature Tw is the temperature outside the cylinder-side water jacket 3W (ie, the outside temperature To). It can be considered that there is a correlation. In this case, when the cooling water temperature Tw with respect to the generated heat amount integrated value ΣW at the time of the determination is equal to or lower than the opening allowable temperature threshold value Twc, the amount of heat generated by the internal combustion engine 1 (that is, the inner wall temperature Ti) This means that the increase in water temperature (ie, the outside temperature To) is small. As a result, it can be determined that the inner wall temperature Ti has a higher temperature rise than the outer temperature To, and the possibility of unacceptable opening of the mouth is high.

  When the cooling water temperature Tw with respect to the generated heat amount integrated value ΣW at the time of the determination is higher than the opening allowable temperature threshold value Twc, the cooling water temperature (that is, outside) with respect to the heat amount (that is, the inner wall temperature Ti) generated by the internal combustion engine 1 An increase in temperature To) is appropriate. As a result, the rising speeds of the inner wall temperature Ti and the outer temperature To are comparable, and it can be determined that no unacceptable mouth opening occurs.

  The opening of the mouth is highly likely to occur between the cold start of the internal combustion engine 1 and the completion of warm-up. The opening restriction control according to the present embodiment starts after the cold start of the internal combustion engine 1 and is executed at least until the thermostat 22 shown in FIG. 2 is opened. FIG. 9 shows the time variation of the opening amount C when t = 0 when the internal combustion engine 1 is cold-started. FIG. 9 shows the result of operation with the accelerator fully opened immediately after the cold start of the internal combustion engine 1 and with the output of the internal combustion engine 1 being high, that is, with the amount of heat generated by the internal combustion engine 1 being large.

  The opening amount C increases with the lapse of time after starting the internal combustion engine 1, and reaches the maximum value Cm at t = t1. Thereafter, the opening amount C decreases with time. Here, the thermostat 22 is open at t = t1. Thus, when the thermostat 22 is open, the opening amount C is small. Therefore, the opening suppression control according to this embodiment is performed after the cold start of the internal combustion engine 1 until at least the thermostat 22 is opened. That is, it is executed when the cooling water temperature Tw is lower than a predetermined temperature (thermostat valve opening temperature). Next, the procedure of the mouth opening suppression control according to the present embodiment will be described.

  FIG. 10 is a flowchart showing the procedure of the mouth opening suppression control according to the present embodiment. The opening suppression control according to the present embodiment can be realized by the engine ECU 50 shown in FIG. 1, that is, the operation control device according to the present embodiment. In executing the mouth opening suppression control according to the present embodiment, the control condition determination unit 55 of the engine ECU 50 determines whether or not the thermostat 22 shown in FIG. 2 is closed. Whether or not the thermostat 22 is closed is determined by the control condition determination unit 55 acquiring the detection signal of the thermostat open / close detection sensor 43 shown in FIGS. The thermostat open / close detection sensor 43 can reliably determine whether or not the thermostat 22 is closed.

  Note that whether or not the thermostat 22 is closed may be determined based on the coolant temperature Tw. For example, when the cooling water temperature Tw is equal to or lower than a predetermined temperature (for example, the valve opening temperature of the thermostat 22), it may be determined that the thermostat 22 is closed. In this way, since the thermostat opening / closing detection sensor 43 is not required, the apparatus configuration can be simplified, and as a result, maintenance and inspection can be reduced.

  When it is determined No in step S101, that is, when the control condition determination unit 55 determines that the thermostat 22 is open, the mouth opening suppression control according to the present embodiment is terminated. When it determines with Yes at step S101, ie, when the control condition determination part 55 determines with the thermostat 22 being closed, it progresses to step S102. In step S102, the control condition determination unit 55 determines the cooling water temperature Tw of the internal combustion engine 1 at the current time, that is, when it is determined that an unacceptable opening of the mouth may occur from the cooling water temperature sensor 41 shown in FIGS. get.

  In step S103, the generated heat amount calculation unit 54 of the engine ECU 50 obtains the generated heat amount integrated value ΣW of the internal combustion engine 1. The generated heat amount integrated value ΣW is an integrated value of the amount of heat generated by the internal combustion engine 1 after the cold start of the internal combustion engine 1 until the time when it is determined that an unacceptable opening of the mouth may occur. The generated heat amount integrated value ΣW is obtained from, for example, the amount of air sucked by the internal combustion engine 1 and the amount of injected fuel after the cold start of the internal combustion engine 1 until the time when it is determined that an unacceptable opening may occur. May be. Also, at least one integrated value of the intake air amount of the internal combustion engine 1, the fuel injection amount of the internal combustion engine 1, the output of the internal combustion engine 1, or the accelerator opening of the internal combustion engine 1 is used instead of the generated heat amount integrated value ΣW. Alternatively, it may be used as a parameter relating to the amount of heat generated by the internal combustion engine. If these are used, it is possible to easily estimate the amount of heat generated by the internal combustion engine, which can reduce the calculation load of the engine ECU 50, which is preferable.

  As described above, by using an integrated value such as the amount of heat generated by the internal combustion engine and the amount of intake air of the internal combustion engine 1 as a parameter relating to the amount of heat generated by the internal combustion engine, the mouth opening that cannot be permitted from the cold start of the internal combustion engine 1 is achieved. It is possible to accurately estimate the history of heat generation of the internal combustion engine 1 until it is determined that there is a risk of occurrence. As a result, the accuracy of determining the possibility of unacceptable mouth opening is improved.

  In step S104, the control condition determination unit 55 gives the generated heat amount integrated value ΣW obtained by the generated heat amount calculation unit 54 in step S103 to the opening determination map 60 shown in FIG. 8, and sets the corresponding opening allowable temperature threshold Twc. Ask. Next, it progresses to step S105 and the control condition determination part 55 compares the cooling water temperature Tw acquired by step S102, and the opening | mouth opening allowable temperature threshold value Twc calculated | required by step S104. In addition, since the cooling water temperature Tw should just be obtained by the time of determination in step S105, the timing which acquires the cooling water temperature Tw is not limited to step S102.

  When it is determined No in step S105, that is, when the control condition determination unit 55 determines that Tw> Twc, the opening amount is within the allowable range, and thus the opening control according to the present embodiment is terminated. If it is determined Yes in step S105, that is, if the control condition determination unit 55 determines that Tw ≦ Twc, there is a possibility that an unacceptable size of mouth opening may occur. In this case, the process proceeds to step S106.

  In step S106, the opening suppression unit 56 of the engine ECU 50 retards the ignition timing of the internal combustion engine 1 from the current time. Then, since the temperature of the exhaust gas Ex discharged from the internal combustion engine 1 rises, the cooling loss in the portion surrounded by the cylinder side water jacket 3W and the head side water jacket 2W arranged around the exhaust port 10E shown in FIG. To increase. Thereby, the rising speed of the cooling water temperature Tw of the internal combustion engine 1 becomes larger than the present time. As a result, the cooling water temperature Tw rises early, so that the inside and outside of the cylinder-side water jacket 3W are uniformly warmed up, and the temperature difference between the inner wall temperature Ti and the outside temperature To becomes small, so The difference in thermal expansion between the inner side and the outer side of the jacket 3W is reduced. Thereby, opening of a mouth is suppressed. According to the method of increasing the temperature of the exhaust gas Ex by retarding the ignition timing, the rate of increase of the cooling water temperature Tw can be improved only by changing the control of the ignition timing without adding other members or the like. Can do.

  In the present embodiment, if there is a possibility that an unacceptably large opening may occur, it is sufficient that the rate of increase in the cooling water temperature Tw can be made larger than the present time. It is not limited to the rise in the temperature of the exhaust gas Ex due to corners. For example, when the internal combustion engine 1 is a diesel engine, the fuel injection timing may be retarded from the current time to raise the temperature of the exhaust gas Ex, and the rising speed of the cooling water temperature Tw may be made larger than the current time. Further, when the cooling water of the internal combustion engine 1 is also used for cooling an automatic transmission, for example, the cooling of the automatic transmission or the like is stopped, so that the mass of the cooling water received from the internal combustion engine 1 is reduced and the cooling water is cooled. The rising speed of the water temperature Tw may be made larger than the current time. Furthermore, a heating means for cooling water may be provided, and this may be used to increase the rising speed of the cooling water temperature Tw from the current time. Further, after combustion at the normal fuel injection timing, additional fuel is injected at a timing that does not become the torque of the internal combustion engine 1, and this fuel is combusted in the expansion stroke of the internal combustion engine 1, thereby generating exhaust gas Ex. The temperature may be increased and the rate of increase of the cooling water temperature Tw may be increased from the current time.

  As described above, in the present embodiment, when suppressing the opening, it is determined that an unacceptable opening may occur based on the cooling water temperature of the internal combustion engine. Increase the coolant temperature. Thereby, opening of a mouth can be suppressed. Further, since it is not necessary to increase the number of gaskets interposed between the cylinder head and the cylinder block or to change the type of the gasket, an increase in cost due to the gasket change can be suppressed. Further, the cooling water temperature (opening allowable temperature threshold) when determining whether or not the opening is allowable is set based on the amount of heat generated by the internal combustion engine, so that the operating conditions of the internal combustion engine 1 are taken into consideration. Thus, it is possible to reliably determine whether or not there is a possibility that unacceptable mouth opening occurs.

  As described above, the operation control apparatus for an internal combustion engine according to the present invention is useful for an internal combustion engine in which a piston reciprocates in a cylinder, and particularly suppresses an opening between a cylinder block and a cylinder head. Suitable for that.

It is a schematic block diagram of the internal combustion engine which concerns on this embodiment, and the operation control apparatus of an internal combustion engine. It is a schematic diagram which shows the cooling system of the internal combustion engine which concerns on this embodiment. It is an enlarged view which shows the connection part of the cylinder head and cylinder block of the internal combustion engine which concerns on this embodiment. It is a conceptual diagram for demonstrating the opening phenomenon which a cylinder head and a cylinder block open. It is a conceptual diagram for demonstrating the opening phenomenon which a cylinder head and a cylinder block open. It is a conceptual diagram which shows the relationship between the inner wall temperature of a cylinder, the outer side temperature of a cylinder, and a cooling water temperature when an internal combustion engine is drive | operated by high output immediately after cold start. It is a conceptual diagram which shows the relationship between opening amount and the temperature difference of the inner wall temperature of a cylinder, and the outer temperature of a cylinder. It is a conceptual diagram which shows the opening determination map used for opening suppression control which concerns on this embodiment. It is a schematic diagram which shows an example of the time change of opening amount. It is a flowchart which shows the procedure of the mouth opening suppression control which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1S Cylinder 2 Cylinder head 2W Head side water jacket 3 Cylinder block 3A Cylinder outer side 3B Cylinder inner wall 3W Cylinder side water jacket 4 Piston 5 Connecting rod 6 Crankshaft 8 Spark plug 15 Fuel injection valve 16 Gasket 21 Radiator 22 Thermostat 24 Water Pump 40 Accelerator opening sensor 41 Cooling water temperature sensor 42 Air flow sensor 43 Thermostat open / close detection sensor 50 Engine ECU
51 I / O section (I / O)
52 Processing Unit 53 Storage Unit 54 Generated Heat Amount Calculation Unit 55 Control Condition Determination Unit 56 Suppression Unit 60 Opening Determination Map B In-Cylinder Combustion Unit

Claims (5)

A calorific value calculation unit for obtaining a parameter relating to the calorific value generated by the internal combustion engine;
Based on the parameters, a permissible opening temperature threshold for determining the possibility of unacceptable opening between the cylinder head and the cylinder block of the internal combustion engine is obtained, and a cooling medium for cooling the internal combustion engine is determined. A control condition determination unit that acquires a temperature and compares the acquired temperature of the cooling medium with the opening allowable temperature threshold;
When the temperature of the cooling medium is equal to or lower than the mouth opening allowable temperature threshold, the mouth opening suppressing unit that increases the rate of temperature rise of the cooling medium from the current time;
An operation control device for an internal combustion engine, comprising: The mouth opening suppression part is
The operation control apparatus for an internal combustion engine according to claim 1, wherein the temperature of the exhaust gas discharged from the internal combustion engine is increased from the current time. The mouth opening suppression part is
The operation control device for an internal combustion engine according to claim 2, wherein the temperature of the exhaust gas is raised by retarding the ignition timing of the internal combustion engine from the present time.   The operation control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the parameter relating to the amount of heat generated by the internal combustion engine uses an integrated value of the parameter integrated from the start of the internal combustion engine. .   The parameter relating to the amount of heat generated by the internal combustion engine is at least one integrated value of the intake air amount of the internal combustion engine, the fuel injection amount of the internal combustion engine, the output of the internal combustion engine, or the accelerator opening of the internal combustion engine. The operation control apparatus for an internal combustion engine according to claim 4, wherein the operation control apparatus is used.

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