JP2011214565A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of avoiding the occurrence of various ill effects such as control instability resulting from the execution of engine control based on the detected temperature of cooling water temporarily falling in reliability when starting circulation of cooling water.SOLUTION: The control device for the internal combustion engine includes a cooling water passage 70, a water temperature sensor 81, a water pump 63 capable of stopping the discharge of cooling water without depending on the engine speed, and a cooling device 60 stopping driving of the water pump 63 when the cooling water temperature is lower than a predetermined temperature in engine warming-up. When cooling water is discharged to start circulation of cooling water, at least one of engine control of incorporating the cooling water temperature as control information such as EGR control and valve timing control is maintained as it is in the control state when starting circulation of cooling water until the lapse of a transient period which is a period in which a temporary temperature change in each part of the cooling water passage 70 caused by the circulation of cooling water is converged.

Description

  The present invention relates to a control device for an internal combustion engine including a cooling device that circulates cooling water by a pump capable of stopping discharge of cooling water to a cooling water passage without depending on engine rotation speed.

  Examples of the cooling device as described above include those described in Patent Document 1. In this cooling device, when the temperature of the cooling water of the internal combustion engine detected by the water temperature sensor at the time of engine warm-up is less than a predetermined temperature, the water pump is stopped to stop the circulation of the coolant to warm up the engine. To promote. Then, when the temperature of the cooling water becomes equal to or higher than a predetermined temperature, the water pump is driven to start circulation of the cooling water.

  In general, in engine control that takes in the temperature of the cooling water as part of the control information, the cooling water including the execution start / end timing is controlled based on the temperature of the cooling water detected by the water temperature sensor each time. Based on the temperature, the control mode is set so as to conform to the temperature of the cooling water.

JP 2009-216028 A JP 2008-180180 A

  By the way, when cooling water is circulated by starting the operation of the water pump from the state where the circulation of the cooling water is stopped by stopping the driving of the water pump when the engine is warmed up, the engine combustion chamber is formed in the cooling water passage. While the high-temperature cooling water existing in the vicinity flows into the other low-temperature parts, the cooling water in the low-temperature parts flows into the high-temperature parts near the engine combustion chamber, etc. The amount of heat exchange of the water temporarily changes greatly, and the detected water temperature detected by the water temperature sensor also fluctuates accordingly. However, such fluctuations in the detected water temperature are temporary that occur immediately after the circulation of the cooling water and are not very reliable as temperature information. Therefore, engine control is performed based on these detected water temperatures. Even so, it is difficult to say that this is in accordance with the temperature conditions of the internal combustion engine and various thermal devices. Rather, by executing the engine control based on such detected water temperature, there is a possibility of causing various adverse effects such as execution / stop when the engine control is unnecessary, or destabilization of the control.

  For example, in the engine control that takes in the detected water temperature detected by the water temperature sensor as control information, such as valve timing control or EGR control described in Patent Document 2, the following problems cannot be ignored. That is, when those controls are stopped due to fluctuations in the detected water temperature, the exhaust properties are improved by performing the EGR control and the valve timing is compared with the case where each control is continuously executed. Executing the control may hinder the improvement of fuel consumption and engine output.

  The present invention has been made in view of such circumstances, and an object of the present invention is to execute engine control based on the detected water temperature of the cooling water whose reliability has temporarily decreased at the start of circulation of the cooling water. It is an object of the present invention to provide a control device for an internal combustion engine that can avoid various adverse effects such as instability of control caused by the problem.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, the cooling water passage through which the cooling water circulates, the water temperature sensor for detecting the temperature of the cooling water, and the discharge of the cooling water to the cooling water passage can be stopped without depending on the engine rotation speed. And a cooling device that stops driving the pump when the detected water temperature detected by the water temperature sensor when the engine is warmed up is lower than a predetermined temperature, and drives the pump when the detected water temperature is equal to or higher than the predetermined temperature. And at least one of engine controls for taking in the detected water temperature as control information when cooling water is discharged into the cooling water passage by the pump and circulation of the cooling water is started. The circulation of the cooling water is continued until a transient period, which is a period in which the temporary temperature change in each part of the cooling water passage caused by the circulation of the cooling water converges, has elapsed. Is summarized in that the maintained in the control state when started.

  In general, in engine control that takes in the temperature of cooling water as part of the control information, based on the temperature of the cooling water detected each time, including the start / end time of its execution, The control mode is set as follows.

  By the way, when the cooling water circulation is started by stopping the circulation of the cooling water by stopping the driving of the pump when the engine is warmed up, the cooling water is circulated near the engine combustion chamber in the cooling water passage. While the existing high-temperature cooling water flows into the other low-temperature parts, the low-temperature part cooling water flows into the high-temperature parts such as the vicinity of the engine combustion chamber. The amount of exchange changes greatly temporarily, and the detected water temperature detected by the water temperature sensor also varies accordingly. However, such fluctuations in the detected water temperature are temporary that occur immediately after the circulation of the cooling water and are not reliable as temperature information. Therefore, engine control was executed based on these detected water temperatures. However, it is hard to say that this is in accordance with the temperature conditions of the internal combustion engine and various thermal equipment. Rather, by executing the engine control based on such a transient change in the detected water temperature, the engine control is executed / stopped when it is unnecessary, or the control becomes unstable. There is a fear.

  In this invention, immediately after canceling the circulation stop of the cooling water when the engine is warmed up, that is, the high-temperature cooling water and the low-temperature cooling water in the cooling water passage are not yet sufficiently mixed, and are detected by the water temperature sensor. In the transition period in which the detected water temperature of the cooling water changes greatly, at least one of the engine controls that take in the detected water temperature as control information until the transition period elapses, that is, as the cooling water circulation starts. Until the temporary temperature change in each part of the generated cooling water passage converges, the control state when the circulation of the cooling water is started is maintained. As a result, various adverse effects such as instability of control due to engine control being executed based on the detected coolant temperature whose reliability has temporarily decreased at the start of cooling water circulation. It will be possible to avoid it.

  In addition, 1. 1. When the water temperature detected by the water temperature sensor becomes equal to or higher than a predetermined temperature. 2. When a drive signal for starting the operation of the pump is output to the pump based on the detected water temperature being equal to or higher than a predetermined temperature; 3. When the pump enters an operating state based on the drive signal. 4. When cooling water is circulated by operating the pump; When the detected water temperature of the water temperature sensor changes with the start of the circulation of the cooling water, it is a series of events that all have a causal relationship, including a slight delay time in that order. “When the cooling water is discharged into the cooling water passage by the pump and circulation of the cooling water is started”, that is, the above 4 and the above 1 to 3 and 5 are all treated as the same meaning.

  According to a second aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, the detected water temperature is detected after the detected water temperature reaches the predetermined temperature and circulation of cooling water is started during the transition period. Is set to a period until the predetermined temperature is reached again.

  As described above, when the circulation of the cooling water is started, in the cooling water passage, the high-temperature cooling water flows from the vicinity of the engine combustion chamber or the like into the low-temperature portion, while the cooling water in the low-temperature portion is near the engine combustion chamber or the like. Therefore, the amount of heat exchange with the cooling water in each part of the cooling water passage changes greatly temporarily. However, such a change in the heat exchange amount gradually converges, and thereafter, the detected water temperature of the water temperature sensor and the temperature of the cooling water in each part of the cooling water passage change with high correlation. According to this configuration, the transition period can be set to an appropriate length as the period for reaching such a situation.

  According to a third aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, in the transient period, the pump after the detected water temperature detected reaches the predetermined temperature and circulation of cooling water is started. The discharge amount integrated value is set to a period until it reaches a predetermined amount.

  As described above, when the circulation of the cooling water is started, in the cooling water passage, the high-temperature cooling water flows from the vicinity of the engine combustion chamber or the like into the low-temperature portion, while the cooling water in the low-temperature portion is near the engine combustion chamber or the like. Therefore, the amount of heat exchange with the cooling water in each part of the cooling water passage changes greatly temporarily. However, since the change in the heat exchange amount gradually converges as the total amount of cooling water discharged from the pump to the cooling water passage increases, the cooling water temperature detected by the water temperature sensor and the cooling water in each part of the cooling water passage are thereafter increased. The temperature changes with a high correlation. According to this configuration, the transition period can be set to an appropriate length so as to be a period for reaching such a situation.

According to a fourth aspect of the present invention, there is provided a control apparatus for an internal combustion engine according to the third aspect, wherein the predetermined amount is set to be equal to or larger than an amount of cooling water staying in the cooling water passage.
In this configuration, the cooling water in each part of the cooling water passage including the vicinity of the engine cooling chamber is made through a discharge of the cooling water from the pump, so that the cooling water passage temporarily increased as the cooling water circulation starts. After the amount of heat exchange with the cooling water in each part again decreases, in other words, after the temperature detected by the water temperature sensor and the temperature of the cooling water in each part of the cooling water passage change with high correlation, Engine control based on the water temperature detected by the water temperature sensor is executed. As a result, the transition period can be set to an appropriate length so as to be a period for reaching such a situation.

  In addition, the pump discharge amount integrated value is further provided with a rotation speed sensor for detecting the rotation speed of the pump as in the invention described in claim 5, and the discharge amount integrated value is determined by the rotation speed sensor. It can be calculated through a configuration in which it is calculated based on the detected rotational speed of the pump and the operating time of the pump.

  According to a sixth aspect of the present invention, in the control device for an internal combustion engine according to any one of the first to fifth aspects, the engine control that takes in the detected water temperature as control information is a part of the exhaust gas from the exhaust system. The EGR control is introduced into the intake system as gas and recirculated, and the EGR control is characterized in that its execution is started from a temperature range where the detected water temperature is lower than the predetermined temperature.

  When the detected water temperature reaches the predetermined temperature and the circulation of the cooling water is started, the cooling water in the low temperature portion of the cooling water passage comes into contact with the water temperature sensor, and the detected water temperature temporarily decreases as described above. Here, when the EGR control is started before the detected water temperature detected by the water temperature sensor reaches a predetermined temperature for canceling the circulation stop of the cooling water, the detected water temperature is changed to the EGR control by the temporary decrease. If the temperature falls below the permitted temperature range, the execution of EGR control is temporarily stopped. However, as described above, such a temporary decrease in the detected water temperature is transient and does not accurately simulate the temperature of the engine combustion chamber. Therefore, if the execution of the EGR control is stopped in this way, The execution opportunity of the EGR control is unnecessarily limited. As a result, compared with the case where the EGR control is continuously executed, the exhaust property is deteriorated. Particularly, since the temperature of the engine combustion chamber is not sufficiently increased immediately after the circulation stop of the cooling water is cancelled, such deterioration of the exhaust property tends to become more remarkable.

  In this respect, according to the above-described configuration, it is possible to avoid the EGR control from being stopped unnecessarily as the circulation of the cooling water is started, and to suppress the deterioration of the exhaust properties. Become.

  According to a seventh aspect of the present invention, in the control device for an internal combustion engine according to any one of the first to sixth aspects, the engine control for taking in the detected water temperature as control information is at least one of an intake valve and an exhaust valve. This valve timing control is characterized in that its execution starts from a temperature range where the detected water temperature is lower than the predetermined temperature.

  When the detected water temperature reaches the predetermined temperature and the circulation of the cooling water is started, the cooling water in the low temperature portion of the cooling water passage comes into contact with the water temperature sensor, and the detected water temperature temporarily decreases as described above. Here, if the execution of the valve timing control has already started before the detected water temperature detected by the water temperature sensor reaches a predetermined temperature at which the circulation stop of the cooling water is released, the detected water temperature becomes the valve timing due to this temporary decrease. If the temperature falls below a temperature range where the execution of the control is permitted, the execution of the valve timing control is temporarily stopped. However, as described above, such a temporary decrease in the detected water temperature is transient and does not accurately simulate the temperature of the engine combustion chamber, so that the execution of the valve timing control is stopped in this way. Then, the execution opportunity of the valve timing control is unnecessarily limited. As a result, the optimum valve timing according to the engine operating state cannot be obtained, and it becomes difficult to improve the fuel consumption and the engine output as compared with the case where the valve timing control is continuously executed. .

  In this regard, according to the above configuration, the valve timing control can be avoided from being stopped unnecessarily as the cooling water circulation starts, and the valve timing can be improved in improving fuel consumption and engine output. Can be set to an optimal value.

  According to an eighth aspect of the present invention, in the internal combustion engine control device according to any one of the first to seventh aspects, the pump is connected between a rotating shaft and an engine output shaft interposed therebetween. An engine-driven water pump that is connected / disconnected through the clutch, and when the detected water temperature is lower than the predetermined temperature, the clutch is disengaged to stop driving the pump, while the detected water temperature When the temperature is equal to or higher than the predetermined temperature, the pump is driven by engaging the clutch.

  According to the present invention, the drive is stopped without depending on the engine rotational speed through a relatively easy configuration change such as diverting a commonly used engine-driven pump and adding a clutch to the pump. The function can be given to the pump.

The block diagram which shows the structure of the periphery of an engine main body, and the structure of a cooling device about one Embodiment which actualized the control apparatus of the internal combustion engine of this invention. (A) is a map set by engine rotational speed and accelerator operation amount, (b) is a graph which shows the relationship between cooling water temperature and a correction coefficient. The flowchart which shows the process sequence about the correction control of the cooling water temperature concerning the embodiment. The timing chart which shows the operation example of correction | amendment control of the cooling water temperature of the embodiment.

With reference to FIGS. 1-4, one Embodiment which actualized the control apparatus of the internal combustion engine concerning this invention is described.
As shown in FIG. 1, in the combustion chamber 13 of the internal combustion engine 1, there are an intake passage 21 for taking intake air into the combustion chamber 13 from the outside and an exhaust passage 31 for discharging the exhaust of the combustion chamber 13 to the outside. It is connected. The air-fuel mixture of the intake air flowing in through the intake passage 21 and the fuel injected from the fuel injection valve 14 when the intake valve 22 is opened is ignited by the spark plug 15 and burned in the combustion chamber 13. As a result, the piston 16 reciprocates and the engine output shaft, that is, the crankshaft 17 rotates. Thereafter, the exhaust from the combustion chamber 13 is discharged to the exhaust passage 31 when the exhaust valve 32 is opened.

  Further, the internal combustion engine 1 has various EGR devices 40, variable valve gears 50, and cooling devices 60 in order to improve exhaust properties, improve fuel efficiency and engine output while maintaining a stable engine combustion state. A device is provided.

  For example, the EGR device 40 includes an EGR passage 41 that communicates the exhaust passage 31 and the intake passage 21 and recirculates a part of the exhaust gas flowing through the exhaust passage 31 to the intake passage 21 as EGR gas, and an EGR of the EGR passage 41. An EGR cooler 42 that cools the gas and an EGR valve 43 that adjusts the amount of EGR gas are provided. In such an EGR device 40, the amount of exhaust gas flowing into the exhaust passage 31 is adjusted by the EGR valve 43 based on the engine operating state, and after the adjusted EGR gas is cooled by the EGR cooler 42, the intake passage Reflux to 21. Thus, by recirculating the EGR gas based on the engine operating state, it becomes possible to improve exhaust properties and fuel consumption.

  The variable valve operating device 50 changes the relative rotational phase of the camshaft 23 that opens and closes the intake valve 22 with respect to the crankshaft 17 based on the hydraulic pressure of hydraulic oil supplied from an oil pump (not shown). The valve timing of the intake valve 22 is changed based on the engine operating state. Thus, by changing the valve timing based on the engine operating state, it becomes possible to improve fuel efficiency and engine output.

  The cooling device 60 includes a radiator 61 that cools the cooling water, a thermostat 62 that adjusts the amount of cooling water flowing into the radiator 61 by switching the flow path of the cooling water, and temporarily stops discharging the cooling water. A water pump 63 is provided. In addition, the apparatus 60 includes a cooling water passage 70 including a water jacket 71 formed in the cylinder block 11 and the cylinder head 12 and including various passages for connecting the radiator 61, the thermostat 62, the water pump 63, and the like. It has been. The cooling device 60 cools the vicinity of the combustion chamber 13 of the internal combustion engine 1 to an appropriate temperature by circulating the cooling water discharged from the water pump 63 in the cooling water passage 70.

  In addition to the water jacket 71, the cooling water passage 70 connects the outlet of the water jacket 71 and the EGR cooler 42, and connects the outlet of the cooler 42 and the inlet of the thermostat 62, and the outlet of the water jacket 71. And a radiator passage 73 connecting the outlet of the radiator 61 and the inlet of the thermostat 62, an intermediate portion of the passage connecting the outlet of the water jacket 71 and the inlet of the radiator 61, and the thermostat 62. A bypass passage 74 that connects the inlet, and a pump passage 75 that connects the outlet of the thermostat 62 and the inlet of the water pump 63 are configured.

  The thermostat 62 is a temperature-sensitive type in which the position of a valve body provided therein opens and closes according to the temperature of the cooling water (cooling water temperature THW), and includes a cooler passage 72, a radiator passage 73, a bypass passage 74, and a pump passage. The flow rate of the cooling water flowing through the radiator 61 is adjusted by changing the communication state with 75. The water pump 63 includes a clutch 18 interposed between a rotating shaft (not shown) and the crankshaft 17. When the clutch 18 is engaged, the rotating shaft of the water pump 63 and the crankshaft 17 are connected, and the water pump 63 is driven. Further, when the connection state between the rotary shaft and the crankshaft 17 is released through the clutch 18, the driving of the water pump 63 is stopped.

Next, the circulation mode of the cooling water in the cooling device 60 will be described.
When the coolant temperature THW is low, such as during engine warm-up, and is lower than the valve opening temperature of the thermostat 62, the thermostat 62 is closed and the radiator passage 73 is blocked. As a result, all of the cooling water flowing out from the engine body 10 circulates through the cooler passage 72, the bypass passage 74 and the pump passage 75.

  On the other hand, when the cooling water temperature THW becomes equal to or higher than the valve opening temperature of the thermostat 62 as after engine warm-up, the radiator passage 73 is opened because the thermostat 62 is opened. As a result, the cooling water flowing out of the engine body 10 is circulated to the radiator 61 through the radiator passage 73 in addition to the cooler passage 72, the bypass passage 74 and the pump passage 75.

  By the way, after the engine is started, it is desirable to complete the engine warm-up at an early stage in order to improve the fuel efficiency and the stability of the combustion state. Therefore, in the cooling device 60 of the present embodiment, the driving of the water pump 63 is stopped until the engine warm-up progresses to some extent, and the circulation of the cooling water in the cooling water passage 70 is prohibited.

  Specifically, when the coolant temperature THW is lower than the predetermined temperature TP, the connection state of the rotating shaft of the water pump 63 and the crankshaft 17 by the clutch 18 is released, and the water pump 63 is stopped. On the other hand, when the coolant temperature THW is equal to or higher than the predetermined temperature TP, the rotating shaft of the water pump 63 and the crankshaft 17 are connected by the clutch 18. As a result, the water pump 63 rotates together with the crankshaft 17 and discharges an amount of cooling water corresponding to the rotation speed (engine rotation speed).

  In addition to the cooling device 60, various devices of the internal combustion engine 1 such as the EGR device 40 and the variable valve operating device 50 described above are comprehensively controlled through the control device 80. The control device 80 includes a CPU, a memory, an A / D conversion circuit, a drive circuit, and the like. The control device 80 includes a water temperature sensor 81 for detecting the temperature of the cooling water flowing near the outlet of the cylinder head 12 in the water jacket 71, an accelerator position sensor 82 for detecting the accelerator operation amount, and a rotation for detecting the engine speed. Various sensors such as a speed sensor 83 are connected. The control device 80 takes in the detection signals of these sensors as appropriate, thereby operating the fuel injection valve 14 to adjust the fuel injection amount and the fuel injection timing, the fuel injection control for controlling the ignition timing by the spark plug 15, EGR control for adjusting the amount of EGR gas recirculated to the intake passage 21 by operating the EGR valve 43, valve timing control for setting the valve timing according to the engine operating state, and a clutch for switching the engagement / release state of the clutch 18 Each control such as control is performed on the internal combustion engine 1.

  Here, in the EGR control, maps using the accelerator operation amount (or load factor (current engine load / engine load maximum value)) calculated by the accelerator position sensor 82 and the rotation speed sensor 83 and the engine rotation speed as parameters, respectively. Based on (see FIG. 2A), the basic opening degree θBASE of the EGR valve 43 is calculated. Next, the basic opening degree θBASE calculated in this way is further corrected based on the coolant temperature THW. Specifically, as shown in FIG. 2B, the correction coefficient K is calculated based on the coolant temperature THW, and the opening degree θ of the EGR valve 43 is calculated based on the following equation (1).

θ ← θBASE · K (1)

As shown in FIG. 2B, the correction coefficient K is set to a value equal to or greater than “0” when the control start temperature TEGR is equal to or higher than the control start temperature TEGR. In other words, when the temperature reaches TEGR, in other words, it starts from a temperature range lower than a predetermined temperature TP for determining whether or not to stop the circulation of the cooling water. The control start temperature TEGR is set in advance through a test or the like as a temperature that can maintain a stable combustion state even when the EGR gas is recirculated, and is set to a temperature lower than the predetermined temperature TP. Is set.

  In the valve timing control, the detection signals of various sensors are taken, and a target angle of the valve timing suitable for the engine operating state is set based on the detection signals, and the target angle and the actual valve timing are matched. The relative rotation phase of the camshaft 23 with respect to the crankshaft 17 is controlled. Further, this valve timing control is performed by taking in the coolant temperature THW as the control information. Specifically, when the coolant temperature THW is low, such as during engine warm-up, the valve timing is set to the most retarded angle in order to suppress the exhaust blowback and stabilize the combustion state. That is, the valve timing control is substantially stopped. On the other hand, when the cooling water temperature THW becomes equal to or higher than the control start temperature TVVT, which is lower than the predetermined temperature TP, after the completion of warm-up, the optimum valve timing according to the engine operating state is achieved in order to improve the fuel consumption and the engine output. Valve timing control is executed so that That is, this valve timing control is also started from a temperature range where the cooling water temperature THW is lower than the predetermined temperature TP at which the cooling water starts to circulate, as in the EGR control.

  Here, when cooling water is circulated by starting the operation of the water pump 63 from the state where the circulation of the cooling water is stopped by stopping the driving of the water pump 63 when the engine is warmed up, The existing high-temperature cooling water flows into a low-temperature cooling water passage other than the jacket 71. On the other hand, the low-temperature cooling water existing other than the water jacket 71 flows into the high-temperature water jacket 71. As a result, the amount of heat exchange with the cooling water in each part of the cooling water passage 70 changes greatly temporarily, and the cooling water temperature THW also varies accordingly. In this case, the above-described EGR control and valve timing control are performed as a result of the fluctuations in the cooling water temperature THW, that is, the cooling water temperature THW temporarily decreases, so that the temperature falls below the control start temperatures TEGR and TVVT. May be unnecessarily stopped.

  Therefore, in the present embodiment, when the circulation of the cooling water is started in each control of the internal combustion engine 1 until the temporary temperature change in each part of the cooling water passage 70 caused by the circulation of the cooling water converges. In order to maintain this control state as it is, “cooling water temperature correction control” is executed, and various controls are executed based on the cooling water temperature THW obtained thereby. The specific processing contents of this control will be described below with reference to FIG. This process is repeatedly executed by the control device 80 every predetermined calculation cycle.

  First, in step S110, it is determined whether or not the cooling water temperature THW detected from the water temperature sensor 81 is equal to or higher than a predetermined temperature TP. Here, the predetermined temperature TP indicates whether or not the engine warm-up has progressed to some extent, in other words, whether or not local boiling occurs in the coolant near the combustion chamber 13 when the circulation of the coolant is stopped as it is. A value for determination is set in advance through a test or the like and stored in the memory of the control device 80. The predetermined temperature TP is set to a value lower than the valve opening temperature of the thermostat 62. When it is determined in step S110 that the coolant temperature THW is lower than the predetermined temperature TP, the driving of the water pump 63 is stopped in step S160. That is, the engine warm-up is promoted by stopping the circulation of the cooling water in the cooling water passage 70.

  On the other hand, when it is determined in step S110 that the coolant temperature THW is equal to or higher than the predetermined temperature TP, steps S120 and S130 are executed. That is, after setting the value of the coolant temperature THW taken as control information in various engine controls to the predetermined temperature TP (step S120), the water pump 63 is driven (step S130).

  Next, in step S140, it is determined whether or not the actual cooling water temperature THW taken from the water temperature sensor 81 is equal to or higher than a predetermined temperature TP. When it is determined in step S140 that the cooling water temperature THW is lower than the predetermined temperature TP, the determination in step S140 is repeated again, and the cooling water temperature THW is set to the predetermined temperature TP until an affirmative result is obtained in this determination processing. Maintain state. On the other hand, when it is determined in step S140 that the actual cooling water temperature THW has become equal to or higher than the predetermined temperature TP, the process of fixing the cooling water temperature THW to the predetermined temperature TP is canceled in step S150. That is, the coolant temperature THW is updated as needed with the actual coolant temperature THWnew at that time detected by the coolant temperature sensor 81.

  Next, referring to FIG. 4, the cooling water temperature THW, the setting mode of the cooling water temperature THW, the execution mode of EGR control, the execution mode of valve timing control, and the driving state of the water pump 63 when the series of processes described above are executed. An example of the transition will be described.

  When the coolant temperature THW becomes equal to or higher than the control start temperature TEGR of EGR control at the timing t1 shown in FIG. 4, EGR control is started, and an amount of EGR gas corresponding to the engine operating state passes through the exhaust passage 31 and the EGR passage 41. Then, the air is recirculated to the intake passage 21.

  Next, when the coolant temperature THW becomes equal to or higher than the control start temperature TVVT of the valve timing control at the timing t2, the valve timing control is started, and the valve timing of the intake valve 22 is changed based on the engine operating state. .

  Thereafter, when the coolant temperature THW becomes equal to or higher than the predetermined temperature TP at the timing t3, the driving of the water pump 63 is started. At this time, the cooling water temperature THW taken in as temperature information for the EGR control and the valve timing control executed by the control device 80 through the “cooling water temperature correction control” described above is fixed to the predetermined temperature TP. Thereby, EGR control and valve timing control are continued.

  Assuming that the correction of the cooling water temperature THW through the previous “cooling water temperature correction control”, that is, the process of fixing the cooling water temperature THW to the predetermined temperature TP has not been executed, as indicated by a one-dot chain line in FIG. Furthermore, the actual cooling water temperature THW detected by the water temperature sensor 81 is predetermined because the heat exchange amount of each part due to the start of the circulation of the cooling water in the cooling water passage 70 temporarily changes greatly. As described above, the situation where the temperature TP temporarily falls below the temperature TP occurs. Then, the cooling water temperature THW detected by the water temperature sensor 81 is temporarily lower than the control start temperature TEGR of the EGR control (timing t5 to t6), or is temporarily lower than the control start temperature TVVT of the valve timing control ( At timings t4 to t7), these controls are stopped, leading to deterioration of exhaust properties, fuel consumption, and engine output. However, since the cooling water temperature THW detected by the water temperature sensor 81 is invalidated and the cooling water temperature THW is fixed to the predetermined temperature TP during a predetermined period after the cooling water circulation stop is canceled through the correction control described above, EGR Control and valve timing control are not temporarily stopped, and exhaust properties are not deteriorated. At time t8, when the actual cooling water temperature THW detected by the water temperature sensor 81 becomes equal to or higher than the predetermined temperature TP again, the fixing of the cooling water temperature THW is released, and the cooling water temperature THW detected by the water temperature sensor 81 is controlled in various ways. To be used.

According to the control device for an internal combustion engine of the present embodiment, the following effects can be obtained.
(1) After canceling the circulation stop of the cooling water when the engine is warmed up, that is, the high-temperature cooling water and the low-temperature cooling water in the cooling water passage 70 are not yet sufficiently mixed, and the cooling water temperature THW changes greatly. In the transition period, the EGR control that takes in the coolant temperature THW as control information is continuously executed during the period until the coolant temperature THW detected by the coolant temperature sensor 81 again reaches the predetermined temperature TP. Accordingly, it is possible to avoid deterioration of exhaust properties due to the EGR control being stopped based on the cooling water temperature THW whose reliability has been temporarily reduced at the start of cooling water circulation. It becomes like this.

  (2) After canceling the circulation stop of the cooling water at the time of engine warm-up, that is, the high-temperature cooling water and the low-temperature cooling water in the cooling water passage 70 are not yet sufficiently mixed, and the cooling water temperature THW changes greatly. During the transition period, the valve timing control for taking in the coolant temperature THW as control information is continuously executed during the period until the coolant temperature THW detected by the coolant temperature sensor 81 again reaches the predetermined temperature TP. As a result, the deterioration of fuel efficiency and the decrease in engine output caused by the stop of the valve timing control based on the cooling water temperature THW whose reliability has been temporarily reduced at the start of the circulation of the cooling water. It will be possible to avoid.

  (3) In the engine control that takes in the value of the cooling water temperature THW as control information, the actual cooling water temperature after the start of the circulation of the cooling water is a period during which the value of the cooling water temperature THW fetched as control information is fixed to the predetermined temperature TP. The period until THW reaches predetermined temperature TP again is set. As a result, after the actual cooling water temperature THW reaches the predetermined temperature TP again, it is possible to execute engine control that captures information on the cooling water temperature THW in accordance with the actual cooling water temperature THW.

  (4) The structure of the water pump 63 is an engine-driven water pump in which the connection state between the rotating shaft of the pump 63 and the crankshaft 17 is connected and disconnected through a clutch 18 interposed therebetween. This makes it possible to stop the drive without depending on the engine rotational speed through a relatively easy configuration change such as diverting a widely used engine-driven pump and adding a clutch to the pump. The water pump 63 can be provided with a function that can be performed.

  (5) After canceling the circulation stop of the cooling water when the engine is warmed up, that is, the high-temperature cooling water and the low-temperature cooling water in the cooling water passage 70 are not yet sufficiently mixed, and the cooling water temperature THW changes greatly. During the transition period, the value of the coolant temperature THW taken as control information in various engine controls is fixed at a predetermined temperature TP. Thereby, for example, by restricting the flow rate of the cooling water, the circulation of the cooling water can be started with a relatively simple structure compared to a structure in which a valve or the like newly provided so that the cooling water temperature THW does not become lower than the predetermined temperature TP is added. On the other hand, various adverse effects such as instability of control due to execution of engine control can be avoided in advance based on the coolant temperature THW whose reliability has temporarily decreased. .

(Other embodiments)
The embodiment of the present invention is not limited to the above-described embodiment, and can be carried out, for example, in the following manner. The following modifications are not applied only to the above-described embodiment, and different modifications can be combined with each other.

  In the above embodiment, EGR control and valve timing control have been described as an example of engine control that takes in the coolant temperature THW as control information. However, other types of engine control are described below. Things. The present invention can also be applied to these engine controls.

  For example, in the internal combustion engine 1, when the coolant temperature THW is low, the fuel injection amount is corrected to be increased based on the coolant temperature THW in order to suppress deterioration of the combustion state. Here, when the circulation of the cooling water is started and the cooling water temperature THW is temporarily lower than the predetermined temperature TP, the fuel injection amount increase correction is executed based on the cooling water temperature THW. There is a concern that the fuel injection amount is unnecessarily increased, leading to deterioration of fuel consumption and exhaust properties. However, according to this modification, it is possible to avoid the occurrence of a problem due to such an excessive increase correction of the fuel injection amount. Even if it is such a structure, there can exist the effect of (3)-(5) mentioned above. Further, the present invention can be applied not only to the fuel injection amount but also to the fuel injection timing.

  In the internal combustion engine 1, when the cooling water temperature THW is low, the ignition timing is advanced based on the cooling water temperature THW in order to promote warming up of the catalyst device provided in the exhaust passage 31. Here, when the circulation of the cooling water is started and the cooling water temperature THW is temporarily lower than the predetermined temperature TP, if the ignition timing is advanced based on the cooling water temperature THW, excessively There is a concern that the ignition timing is advanced and knocking is caused. However, according to this modification, it is possible to avoid the occurrence of a problem due to such an excessive advance of the ignition timing. Even if it is such a structure, there can exist the effect of (3)-(5) mentioned above.

  In the air-fuel ratio control, the fuel injection amount is feedback-corrected so that the air-fuel ratio of the air-fuel mixture burned based on the oxygen concentration in the exhaust gas after the completion of engine warming becomes the stoichiometric air-fuel ratio. Update the learning value. Here, when the circulation of the cooling water is started and the cooling water temperature THW is temporarily lower than the predetermined temperature TP, if the learning value of the air-fuel ratio is updated based on the cooling water temperature THW, the There is a concern that an appropriate value is updated as the learning value of the air-fuel ratio. However, according to this modification, the occurrence of such a problem can be avoided. Even if it is such a structure, there can exist the effect of (3)-(5) mentioned above.

  In the cooling fan control, the rotation of the cooling fan (not shown) is switched to Hi / Lo / stop based on the coolant temperature THW and the operating state of the air conditioner (not shown). For example, when the cooling water temperature THW is low and the air conditioner is stopped, the rotation of the cooling fan is stopped. On the other hand, when the cooling water temperature THW is high and the air conditioner is stopped, the rotation of the cooling fan is Hi. Set to Here, when the circulation of the cooling water is started and the cooling water temperature THW is temporarily lower than the predetermined temperature TP, the cooling fan is stopped based on the cooling water temperature THW. There is a concern that the rotation of the engine is stopped and the internal combustion engine is burned. However, according to this modification, it is possible to avoid the occurrence of a problem due to the stop of the cooling fan. Even if it is such a structure, there can exist the effect of (3)-(5) mentioned above.

  In heater blower control, when the coolant temperature THW is lower than the control start temperature, the heater blower (not shown) is stopped, and when the temperature exceeds the control start temperature, the heater blower is driven to stabilize the temperature in the passenger compartment. To maintain. Here, when the circulation of the cooling water is started and the cooling water temperature THW is temporarily lower than the predetermined temperature TP, if the heater blower is stopped based on the cooling water temperature THW, the heater blower is unnecessarily moved. There is a concern that the vehicle interior temperature cannot be effectively maintained by being stopped. However, according to this modification, it is possible to avoid the occurrence of a problem due to the stop of the heater blower. Even if it is such a structure, there can exist the effect of (3)-(5) mentioned above.

  In the above embodiment, the actual cooling water temperature detected by the water temperature sensor 81 after the cooling water circulation is started during the period in which the value of the cooling water temperature THW captured as control information in various engine controls is set to the predetermined temperature TP. Although the period until THW reaches predetermined temperature TP again is set, the setting mode during synchronization is not limited to this. That is, it can be set to a period until the integrated value of the discharge amount of the water pump 63 after starting the circulation of the cooling water reaches a predetermined amount that is equal to or more than the amount of the cooling water staying in the cooling water passage 70. The discharge amount integrated value is calculated based on the rotational speed of the water pump 63 detected by the rotational speed sensor 83 and the operating time of the pump 63. Even if it is such a structure, there can exist the effect of (1)-(5) mentioned above.

  In the above embodiment, as the engine control that takes in the value of the cooling water temperature THW as control information, EGR control and valve timing at which the control is started from a temperature range where the cooling water temperature THW is lower than the predetermined temperature TP at which the circulation of the cooling water starts. Although control is illustrated, the present invention can also be applied to engine control that is started when the predetermined temperature TP is reached. Even if it is such a structure, there can exist the effect of (1)-(5) mentioned above.

  In the above embodiment, the clutch 18 is provided in the power transmission system between the crankshaft 17 and the rotating shaft of the water pump 63, and the clutch 18 connects and disconnects the power transmission from the crankshaft 17 to the rotating shaft of the water pump 63. However, for example, by bringing a pulley (not shown) that rotates together with the pulley of the crankshaft 17 into contact / separation with a pulley for omitting rotational force from the water pump 63, the water pump is moved from the crankshaft 17 to the water pump 63. It is also possible to connect / disconnect power transmission to the 63 rotating shaft.

  In the above embodiment, the engine-driven water pump 63 that can drive / stop the water pump 63 according to the engaged / released state of the clutch 18 is used, but an electric water pump that is driven by a motor is used. You can also Even if it is such a structure, there can exist the effect of (1)-(3), (5) mentioned above.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 10 ... Engine main body, 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Combustion chamber, 14 ... Fuel injection valve, 15 ... Spark plug, 16 ... Piston, 17 ... Crankshaft, 18 ... Clutch, 21 Intake passage, 22 ... Intake valve, 23 ... Cam shaft, 31 ... Exhaust passage, 32 ... Exhaust valve, 40 ... EGR passage, 41 ... EGR passage, 42 ... EGR cooler, 43 ... EGR valve, 50 ... Variable valve operating device , 60 ... Cooling device, 61 ... Radiator, 62 ... Thermostat, 63 ... Water pump, 70 ... Cooling water passage, 71 ... Water jacket, 72 ... Cooler passage, 73 ... Radiator passage, 74 ... Detour passage, 75 ... Pump passage, DESCRIPTION OF SYMBOLS 80 ... Control apparatus, 81 ... Water temperature sensor, 82 ... Accelerator position sensor, 83 ... Rotation speed sensor.

Claims (8)

A cooling water passage through which the cooling water circulates, a water temperature sensor for detecting the temperature of the cooling water, a pump capable of stopping the discharge of the cooling water to the cooling water passage without depending on the engine rotation speed, and the above-mentioned when the engine is warmed up In a control device for an internal combustion engine, comprising: a cooling device that stops driving of the pump when a detected water temperature detected by a water temperature sensor is lower than a predetermined temperature, and drives the pump when the detected water temperature is equal to or higher than the predetermined temperature. ,
When the cooling water is discharged into the cooling water passage by the pump and circulation of the cooling water is started, at least one of the engine controls that takes in the detected water temperature as control information is generated along with the circulation of the cooling water. Control of the internal combustion engine, characterized in that the control state at the time when the circulation of the cooling water is started is maintained until a transition period in which a temporary temperature change in each part of the cooling water passage converges elapses. apparatus. 2. The internal combustion engine according to claim 1, wherein the transient period is set to a period until the detected water temperature reaches the predetermined temperature again after the detected water temperature detected reaches the predetermined temperature and circulation of cooling water is started. Control device. The transient period is set to a period from when the detected water temperature detected reaches the predetermined temperature until the integrated discharge amount of the pump reaches a predetermined amount after cooling water circulation is started. Control device for internal combustion engine. The control device for an internal combustion engine according to claim 3, wherein the predetermined amount is set to be equal to or greater than an amount of cooling water staying in the cooling water passage. A rotation speed sensor for detecting a rotation speed of the pump is further provided, and the discharge amount integrated value is calculated based on a rotation speed of the pump detected by the rotation speed sensor and an operation time of the pump. 4. The control apparatus for an internal combustion engine according to 4. In the control device for an internal combustion engine according to any one of claims 1 to 5,
The engine control that takes in the detected water temperature as control information is EGR control in which a part of the exhaust gas from the exhaust system is introduced into the intake system as EGR gas and recirculated, and the detected water temperature is less than the predetermined temperature. The control device for an internal combustion engine is characterized in that its execution is started from a lower temperature range. In the control device for an internal combustion engine according to any one of claims 1 to 6,
The engine control that takes in the detected water temperature as control information is valve timing control that changes the valve timing of at least one of the intake valve and the exhaust valve, and the valve timing control is a temperature at which the detected water temperature is lower than the predetermined temperature. The control device for an internal combustion engine, whose execution is started from a region. The pump is an engine-driven water pump in which the connection state between the rotary shaft and the engine output shaft is connected and disconnected through a clutch interposed therebetween,
When the detected water temperature is lower than the predetermined temperature, the driving of the pump is stopped by releasing the clutch, while when the detected water temperature is equal to or higher than the predetermined temperature, the clutch is engaged. A pump is driven. The control device for an internal-combustion engine according to any one of claims 1 to 7 characterized by things.

Images