JP2007177707A - Idling rotation speed control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein learning control or the like of air fuel ratio feed back to be started under the condition of warming up temperature is not started if temperature of cooling water of an engine is saturated without reaching the warming up temperature. <P>SOLUTION: When it is detected that a heater using heat of engine cooling water is operated and that temperature of engine cooling water is saturated below warming up temperature during idling rotation speed control from cold start, idling rotation speed is raised by opening throttle valve wider than throttle valve opening based on temperature of engine cooling water by predetermined opening and cooling water is heated to raise temperature of engine cooling water to warming up temperature. Consequently, temperature of engine cooling water is immediately raised to warming up temperature when temperature of engine cooling water is saturated without reaching warming up temperature due to operation of the heater, learning control or the like of air fuel ratio feed back to be executed under the condition of the warming up temperature is immediately executed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to idle speed control of an internal combustion engine during a warm-up operation from a cold start.

  In recent years, with the development of electronic control technology, particularly digital control technology, an electronically controlled engine in which the air-fuel ratio of the engine is controlled using an electronically controlled fuel injection device has been put into practical use.

  In this electronically controlled engine, in general, during idle operation, the flow rate of intake air introduced by bypassing the throttle valve is controlled in accordance with the difference between the actual engine speed and the target idle speed. The idle rotation speed is fed back to the target idle rotation speed.

Conventionally, a technique disclosed in Patent Document 1 is known for idle rotation speed control of an internal combustion engine. In the invention disclosed in Patent Document 1, when the engine is warmed up and the idle rotation speed control is executed, the feedback control to the target rotation speed is performed regardless of the cooling water temperature after that even if the cooling water temperature decreases. In order to continue, the present invention has been made to solve the problem that the effectiveness of the heater is reduced due to the cooling water temperature being lowered during the idle rotation speed control. Specifically, during idling speed control, it is determined whether the cooling water temperature has decreased, and if it decreases, the idling speed is increased to increase the amount of heat generated by the engine to improve the effectiveness of the heater. It is something to try.
Japanese Patent Publication No. 7-13495

  However, when the engine is cold started and the warm-up operation by the idle rotation speed control is started, the heat generation amount is small because the engine load is small during the idle rotation speed control. In such a cold idle speed control, when the air conditioner is turned on, the cooling water hits the heater core using the cooling water of the engine, thereby depriving the heat of the cooling water. Therefore, as shown in FIG. 2, the engine coolant temperature does not reach the warm-up determination temperature indefinitely and becomes saturated. This phenomenon occurs particularly when the power window is opened when the set temperature in the passenger compartment is slightly lower than the outside air temperature. In the case of winter, since the difference between the indoor set temperature and the outside air temperature is large, the load on the air conditioner increases and the engine idling speed increases. For this reason, the calorific value of the engine becomes large and the above-mentioned disadvantages are unlikely to occur. On the other hand, when the difference between the room temperature and the outside air temperature is small, the heat generated by the air conditioner is small and the engine heat generation is small. On the other hand, the heat of the cooling water is deprived from the heater core and the cooling water temperature is difficult to increase. As a result, the above-mentioned problem occurs. When the engine coolant does not reach the warm-up temperature, there is a problem that the air-fuel ratio feedback learning control, the ISC feedback learning control, the purge control, and the like, which are executed when the engine warm-up temperature is reached, are not executed indefinitely. In the technique of Patent Document 1, the idle rotation speed is increased according to the coolant temperature after the warm-up is completed. When the engine does not reach the warm-up state, the idle rotation speed control is not executed indefinitely. Therefore, the above problem cannot be solved.

  Therefore, the present invention, when it is determined that the cooling water temperature does not reach the warm-up determination temperature and is saturated below the warm-up determination temperature, appropriately increases the engine temperature to quickly learn control of air-fuel ratio feedback, etc. An object of the present invention is to provide an idle rotation speed control device in which the operation is started.

  In view of this, the invention according to claim 1 is directed to an idle rotation speed control device for an internal combustion engine having an idle rotation speed control means for controlling an idle rotation speed from a cold start to a completion of warm-up. A heater operation determining means for determining whether or not, and a determining means for determining whether or not the cooling water temperature of the internal combustion engine is saturated below the warm-up temperature, and in the warm-up operation by the idle rotation speed control means, the heater operation determination means When the operation of the heater is determined by the above and the determination means determines that the cooling water temperature of the internal combustion engine is saturated, a cooling water temperature increasing means for increasing the cooling water temperature of the internal combustion engine is provided.

  Thus, when the operation of the heater using the heat of the cooling water of the internal combustion engine is confirmed during the idle rotation speed control from the cold start to the completion of the warm-up, the determination means determines the cooling water temperature of the internal combustion engine. If it is detected that the engine is saturated without reaching the warm-up temperature, the cooling water temperature of the internal combustion engine is raised by the cooling water temperature raising means, and the internal combustion engine is quickly warmed to the warm-up temperature. As a result, air-fuel ratio feedback learning control, ISC feedback learning control, purge control, etc., which are set to execute control when the warm-up temperature is reached, can be quickly executed even while the heater is operating. It becomes possible.

  The invention according to claim 2 further comprises a time measuring means for counting a duration when the cooling water temperature of the internal combustion engine is in a predetermined temperature range lower than the warm-up temperature, and the judging means is a cooling water temperature counted by the time measuring means. When the continuation time after the temperature reaches a predetermined temperature range lower than the warm-up temperature becomes equal to or greater than a predetermined value for determining that the cooling water temperature is saturated, it is determined that the cooling water temperature of the internal combustion engine is saturated. Thereby, it can be accurately determined whether or not the coolant temperature of the internal combustion engine is saturated.

  In the invention according to claim 3, the time counting means for counting the elapsed time from the start of the internal combustion engine is provided, and the determination means for determining whether or not the cooling water temperature of the internal combustion engine is saturated is counted by the time measuring means. When the elapsed time from the start of the engine reaches or exceeds a predetermined value for determining that the coolant temperature is saturated, it is determined that the coolant temperature of the internal combustion engine is saturated. Thus, by measuring the elapsed time after the internal combustion engine is started, it may be determined whether or not the cooling water temperature of the internal combustion engine is saturated after the elapsed time reaches a predetermined value. Also by this method, it can be accurately determined whether or not the coolant temperature of the internal combustion engine is saturated.

  The predetermined value for determining whether or not the cooling water temperature of the internal combustion engine is saturated varies depending on the starting temperature and the outside air temperature of the internal combustion engine. Therefore, in the invention according to claim 4, the predetermined value for determining that the cooling water temperature is saturated is calculated based on the starting water temperature and / or the outside air temperature of the internal combustion engine. Thus, by appropriately calculating a predetermined value for determining whether or not the cooling water temperature of the internal combustion engine is saturated, it is possible to reduce the influence of the starting temperature and the outside air temperature of the internal combustion engine. This is continued when the predetermined value is constant even though the predetermined value for determining that the cooling water temperature is saturated due to the influence of the temperature at the start of the internal combustion engine and the outside air temperature is higher than normal. Since the time has reached the predetermined value, it is possible to prevent erroneous determination that the cooling water temperature is saturated even though the cooling water temperature is not saturated. In addition, when the predetermined value for determining that the cooling water temperature is saturated due to the influence of the temperature at the start of the internal combustion engine or the outside air temperature is lower than usual, the cooling water temperature is constant. Even if it is saturated, the duration time does not reach the predetermined value, so that it is not determined that it is saturated, so that it is possible to prevent the execution of learning control or the like from being delayed.

  In the invention according to claim 5, the cooling water temperature change amount calculating means for calculating the amount of change in the cooling water temperature of the internal combustion engine is provided, and the determining means for determining whether or not the internal combustion engine is saturated is based on the cooling water temperature change amount calculating means. When the cooling water temperature is lower than the warm-up determination temperature and the change amount is small, it is determined that the cooling water temperature of the internal combustion engine is saturated. By looking at the amount of change in the coolant temperature of the internal combustion engine below the warm-up determination temperature, it is possible to estimate that the coolant of the internal combustion engine does not reach the warm-up temperature. Thus, when it is determined that the cooling water temperature of the internal combustion engine is saturated, the cooling water is quickly heated, and learning control or the like that is executed when the warm-up temperature is reached can be performed.

  When the cooling water of the internal combustion engine is saturated, the cooling water temperature of the internal combustion engine must be quickly raised. Therefore, in the invention according to claim 6, the cooling water temperature raising means raises the cooling water temperature of the internal combustion engine by raising the idle rotation speed of the internal combustion engine. As a result, since the amount of heat generated in the internal combustion engine increases as the idle rotation speed increases, the cooling water temperature of the internal combustion engine can be quickly increased.

  In the invention according to claim 7, in the warm-up operation by the idle rotation speed control means, the idle switch is turned on and the engine rotation speed is equal to or lower than the predetermined rotation speed. During such an idling operation, the amount of heat generated by the internal combustion engine is small, so that the cooling water temperature of the internal combustion engine is likely to be saturated. Therefore, in such an idle motion, it is possible to appropriately raise the cooling water temperature by determining the saturation of the cooling water temperature.

  In the invention according to claim 8, the failure diagnosis prohibiting means for prohibiting the failure diagnosis of the thermostat for opening and closing the passage through which the cooling water circulates between the internal combustion engine and the radiator and / or the cooling water temperature detecting means for measuring the cooling water temperature of the internal combustion engine. When the determination unit determines that the cooling water temperature of the internal combustion engine is saturated, the prohibition unit prohibits failure diagnosis of the thermostat and / or the cooling water temperature detection unit. As a result, when it is determined that the cooling water temperature of the internal combustion engine has been saturated, the cooling water temperature of the internal combustion engine does not increase, and therefore it is possible to prevent erroneous determination that the thermostat and / or the cooling water temperature detection means are faulty. Can do.

  When the cooling water temperature of the internal combustion engine saturates, there are a case where the heat is generated due to the heat of the cooling water temperature of the internal combustion engine being deprived by the heater operation, and a case where the cooling water temperature is caused by a thermostat. Therefore, in the invention according to claim 9, a thermostat failure determining means for determining a failure of a thermostat provided for opening and closing a passage through which the cooling water temperature circulates between the internal combustion engine and the radiator, and a cooling water temperature of the internal combustion engine by the determining means. And a timer for counting the elapsed time from when the cooling water temperature starts to be raised by the cooling water temperature raising means.The thermostat failure judging means raises the cooling water temperature by the cooling water temperature raising means. In spite of this, if the elapsed time counted by the time measuring means does not reach the warm-up temperature without exceeding the warm-up temperature, it is determined that the thermostat is malfunctioning. As a result, when the cooling water temperature of the internal combustion engine is saturated, the cause of the saturation of the cooling water temperature of the internal combustion engine is that the heat of the cooling water temperature of the internal combustion engine is deprived by the heater operation, or due to the open failure of the thermostat It can be judged whether it has occurred. Further, it is possible to efficiently determine the failure of the thermostat by determining whether or not the elapsed time from the start of increasing the cooling water temperature by the cooling water temperature increasing means is a predetermined value.

  The invention according to claim 10 further comprises cooling water temperature estimating means for estimating the cooling water temperature of the internal combustion engine based on the amount of heat generated by the internal combustion engine, and the failure determination means of the thermostat is the estimated cooling calculated by the cooling water temperature estimating means. A failure of the thermostat is determined by comparing the water temperature with the cooling water temperature detected by the cooling water temperature detecting means. Thus, it is possible to accurately determine the failure of the thermostat by comparing the estimated cooling water temperature estimated by the heat generation amount generated in the internal combustion engine by the cooling water temperature increasing means and the cooling water temperature detected by the cooling water temperature detecting means. it can.

[First Embodiment]
Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram of an engine control system which is a premise for adopting an idle speed control device for an internal combustion engine of the present invention. In FIG. 1, an electronic control unit (hereinafter referred to as “ECU”) 2 controls each part of an internal combustion engine (hereinafter referred to as “engine”) 1. The intake system 3 of the engine 1 includes an intake passage 3 and a throttle valve 4. The intake air supplied to the engine 1 is controlled by adjusting the opening of the throttle valve based on a detection signal from an accelerator opening sensor provided in an accelerator pedal (not shown).

  Based on the detection signal of the accelerator opening sensor, the ECU 2 commands the motor to control duty to the throttle motor in order to drive the throttle opening. An injector (not shown) is used to supply an appropriate amount of fuel injection to the intake air to the engine 1 based on a detection signal from an engine speed sensor 5 that detects the engine speed and a detection signal from an air flow meter (not shown). A drive signal is supplied to.

  As a result, the optimal air-fuel mixture is supplied into the cylinder of the engine 1, and the ignition plug (not shown) performs spark ignition at a desired timing, whereby the engine 1 is combusted. Further, the ECU 2 receives a detection signal of an intake air temperature sensor 7 provided in intake air of the engine 1 to detect an outside air temperature and a detection signal of a shift position sensor 6 that detects a gear position in order to perform other corrections. Have been entered. Further, a detection signal indicating whether or not the idle switch is on is input by the idle determination sensor 8.

  Next, the configuration of a cooling system for cooling the engine 1 will be described. The cooling passage 10 includes a path that circulates inside the engine and a path that circulates the radiator 9 outside the engine.

  The thermostat 11 is an open / close valve made of bimetal, and switches whether the coolant is circulated only inside the engine or via the radiator 9 according to the coolant temperature. More specifically, when the engine coolant temperature is low, the open / close valve of the thermostat 11 is closed, and the coolant circulates only inside the engine.

  When the engine coolant temperature is high, the opening / closing valve of the thermostat 11 is opened, and the coolant is circulated through the radiator 9, and the coolant is cooled by the radiator 9. In this way, the cooling water of the engine 1 is maintained at an appropriate water temperature by the opening / closing valve of the thermostat 11, and the temperature inside the engine is adjusted.

  Next, the configuration of an air conditioner (hereinafter referred to as “air conditioner”) that adjusts the temperature in the passenger compartment will be described. As the configuration of the air conditioner, an air conditioner blow fan 15 that takes in air from outside air, an evaporator 16, a heater core 18, and an air mix damper 17 that controls the opening and closing of the heater core 18 are installed in the air conditioner blow passage 14, and air is also provided in the passenger compartment. An air conditioner outlet 19 for blowing out air is installed. The amount of air blown from the air conditioner outlet 19 into the vehicle interior is adjusted by the air conditioner blower fan 15, and the temperature of the air blown into the vehicle interior is adjusted by adjusting the opening of the air mix damper 17 for a part of the air cooled by the evaporator 16. The air temperature of the air conditioner is adjusted by heating with the heater core 18.

  When the driver turns on the air conditioner, the air conditioner control device 13 controls the air conditioner blowing fan 15 and the air mix damper 17 to adjust the air blowing temperature of the air conditioner. Further, since the operation of the compressor that compresses the cooling refrigerant of the air conditioner is controlled by the power of the engine 1 by the ECU 2, information on whether or not the driver has switched on the air conditioner and the air conditioner operation information are sent to the ECU 2 by the air conditioner control device 13. Entered.

  FIG. 4 is a flowchart for controlling the engine 1 by determining whether or not the engine 1 is saturated at a temperature lower than the warm-up temperature and increasing the idle rotation speed in the embodiment of the present invention. This routine is repeatedly executed at predetermined time intervals. When this flowchart is executed, in step 100, the timer Tsat for counting the duration after the engine coolant temperature reaches a predetermined temperature or higher is reset. When the resetting of the timer Tsat is completed, the process proceeds to step 101 to determine whether or not the engine coolant temperature is equal to or lower than the warm-up determination temperature (80 ° C.).

  When the engine coolant temperature is higher than the warm-up determination temperature, the engine coolant temperature has reached the warm-up temperature, and thus this flowchart is ended. When the engine coolant temperature is equal to or lower than the warm-up determination temperature, the process proceeds to step 102 to determine whether or not the engine 1 is in a predetermined state. The predetermined state of the engine 1 is an idle operation in which the load of the engine 1 is small from the time of cold start to the completion of warm-up, and is a state in which the amount of heat generated in the engine 1 is small. When the operating state of the engine 1 is a predetermined state, the process proceeds to step 103. In step 103, the state of the heater is detected. If the heater is on, the process proceeds to step 104. In step 104, it is determined whether or not the engine coolant temperature is equal to or higher than a predetermined temperature. As a specific example, it is determined that the engine coolant temperature is 75 ° C. Thereby, it can be seen that the engine coolant temperature is in the region within 75 ° C. and within the warm-up determination temperature (80 ° C.). If the engine coolant temperature is 75 ° C. or higher in step 104, the process proceeds to step 105.

  In step 105, the timer Tsat is counted up for counting the duration after the temperature reaches a predetermined temperature. In step 106, it is determined whether or not the timer Tsat is equal to or greater than a predetermined value for determining that the engine coolant temperature is saturated. The predetermined value is normally set to a time required until the warm-up is completed after the engine coolant temperature reaches 75 ° C. or a time slightly longer than that. Since this time depends on the outside air temperature and the starting water temperature, it is defined by a three-dimensional map having the outside air temperature and the starting water temperature shown in FIG. 3 as parameters.

  If the timer Tsat is equal to or smaller than the predetermined value, the process returns to step 101, and the processing from step 101 to step 106 is repeated. When the timer Tsat becomes equal to or greater than the predetermined value, it is considered that the engine coolant temperature does not reach the warm-up temperature and is saturated, and the routine proceeds to step 107. When the engine coolant temperature does not reach the warm-up temperature, the learning control of the air-fuel ratio feedback, the learning control of the ISC feedback, the purge control, etc. using the warm-up temperature as an execution condition are not executed at any time. For this reason, it progresses to step 107 and performs control for raising engine cooling water temperature. In step 107, an idle up plug (xIDLUP) is set, and a subroutine for performing heating control of the cooling water in FIG. 5 is called.

  Next, the subroutine of FIG. 5 will be described. When heating the cooling water of the engine 1, the process proceeds to step 108 and the throttle valve 4 is opened to a predetermined opening. By opening the throttle valve 4 by a predetermined opening, the intake air amount is increased and the idle rotation speed of the engine 1 is increased. As the idling speed of the engine 1 increases, the amount of heat generated inside the engine increases, so the temperature of the cooling water circulating inside the engine increases. When the throttle valve 4 is opened by a predetermined opening, the routine proceeds to step 109. In step 109, it is determined whether or not the cooling water of the engine 1 has reached a warm-up determination temperature or higher. If the cooling water of the engine 1 is equal to or lower than the warm-up determination temperature, the throttle opening set in step 108 is maintained until the cooling water of the engine 1 reaches the warm-up determination temperature.

  If it is determined in step 109 that the engine cooling water temperature has become equal to or higher than the warm-up determination temperature, the throttle valve 4 is set to the original opening so that the idle rotation speed becomes a normal idle rotation speed set based on the cooling water temperature. Return to In addition, when the throttle valve 4 is closed and opened to a predetermined opening, the valve may be gradually closed and opened. In this way, torque shock associated with closing and opening of the valve can be reduced, so that deterioration of drivability can be suppressed.

  The control result after the engine start of the first embodiment will be described with reference to the time chart shown in FIG. FIG. 6 is a time chart for explaining the operation of increasing the cooling water temperature by opening the throttle valve 4 and increasing the engine rotation speed when it is determined that the engine cooling water temperature is saturated in the first embodiment. First, when the engine 1 is started, the throttle opening shown in FIG. 6D is set based on the engine coolant temperature shown in FIG. Further, since the engine speed in FIG. 6 (e) changes with respect to the throttle opening in FIG. 6 (d), the engine speed is controlled by adjusting the throttle opening. The throttle opening based on the engine coolant temperature is set to be higher as the engine coolant temperature is lower and lower as the engine coolant temperature is higher.

  As described above, the throttle opening set based on the engine coolant temperature is set to be small when the coolant temperature is close to the warm-up temperature, and the amount of heat generated by the engine is also reduced. When the engine coolant temperature becomes equal to or higher than a predetermined coolant temperature (kTHWLOW: 75 ° C.) at time t1, the timer Tsat starts counting. The engine coolant temperature does not reach the warm-up temperature, and the timer Tsat continues to count up. When the timer Tsat becomes equal to or greater than a predetermined value (kTIMELIMIT) at time t2, it is determined that the engine coolant temperature is saturated, and the idle rotation speed The idle-up flag (xIDLUP) that raises is turned on. When the idle up flag (xIDLUP) is turned on, the throttle valve 4 is gradually opened, and the engine speed gradually increases accordingly.

  As a result, the amount of heat generated by the engine 1 increases, and the engine coolant temperature begins to rise. When the engine coolant temperature becomes equal to or higher than the warm-up determination temperature (kTHWHIG) at time t3, the idle up flag (xIDLUP) for increasing the idle rotation speed is turned off and the timer Tsat is reset. When the idle up flag (xIDLUP) is turned off, the throttle valve 4 is gradually returned to the original opening degree so that the normal idle rotation speed set by the engine coolant temperature is reached, and the engine rotation speed is restored to the original rotation accordingly. Return to speed.

  Thus, in the present embodiment, it is determined that the engine coolant temperature has been saturated when the engine coolant temperature has reached 75 ° C and has not reached 80 ° C for a long time. Then, the engine speed is increased by opening the throttle valve 4 by a predetermined opening, and the coolant temperature is allowed to reach the warm-up temperature. Thereby, learning control of air-fuel ratio feedback, learning control of ISC feedback, purge control, and the like executed when the engine coolant temperature reaches the warm-up temperature are executed. In the present embodiment, the predetermined value for determining whether or not the engine coolant temperature is saturated is set based on the start-up water temperature and the outside air temperature shown in FIG. 3, but may be a fixed value for simplicity. It may be variably set based on only one of the starting water temperature and the outside air temperature.

[Second Embodiment]
The first embodiment differs from the first embodiment in that the saturation of the engine coolant temperature is determined by counting the time from when the engine coolant temperature reaches 75 ° C until it reaches 80 ° C. is there. A second embodiment of the present invention will be described with reference to FIG.

  In FIG. 7, in step 200, it is determined whether or not the engine 1 is at the time of starting. If it is determined that the engine 1 has been started, the routine proceeds to step 201 where the timer Tstart for counting the elapsed time since the start of the engine 1 is reset. On the other hand, when the start of the engine 1 is completed, the routine proceeds to step 202 where the timer Tstart is counted up. In step 203, it is determined whether or not the timer Tstart counted up from the start of the engine is equal to or greater than a predetermined value for determining that the engine coolant temperature is saturated.

  This predetermined value is set to be slightly longer than the time required to reach the warm-up temperature in normal idling from the time of engine start. Since this time depends on the starting water temperature and the outside air temperature, it is defined by the starting water temperature and the outside air temperature using the same three-dimensional map as in FIG. 3 used in the first embodiment. If the timer Tstart is equal to or greater than the predetermined value, the process proceeds to step 204 to determine whether or not the engine coolant temperature is within the warm-up determination temperature (80 ° C.). When the engine coolant temperature is higher than the warm-up determination temperature, the engine coolant temperature has reached the warm-up temperature, and thus this flowchart is ended. When the engine coolant temperature is equal to or lower than the warm-up determination temperature, the process proceeds to step 205, and it is determined whether or not the engine 1 is in a predetermined state.

  The condition of the predetermined state of the engine 1 is a case where the engine 1 is in idling operation and the heat generation amount of the engine 1 is small as in the first embodiment. When the engine 1 is in the predetermined state, the process proceeds to step 206, and it is determined whether or not the heater state is on. When the heater is on, it is determined that the engine cooling water temperature is saturated because the normal engine cooling water has not reached the warm-up temperature since the time when the engine 1 is started. move on.

  In step 207, a subroutine for performing heating control of engine cooling water in FIG. 5 is called. In the present embodiment, the predetermined value for determining whether or not the engine coolant temperature is saturated is set based on the start-up water temperature and the outside air temperature as in FIG. 3, but may be a fixed value for simplicity. Alternatively, it may be set variably based on only one of the starting water temperature and the outside air temperature.

  The control result from the time of engine start of the second embodiment is shown in the time chart shown in FIG. FIG. 8 is a time chart for explaining the operation of opening the throttle valve 4 and increasing the engine speed to increase the engine coolant temperature when it is determined that the engine coolant temperature is saturated. First, when the engine 1 is started, the throttle opening shown in FIG. 6 (d) is set based on the engine coolant temperature shown in FIG. 6 (a).

  In addition, the timer Tstart that counts the elapsed time from the start of the engine starts counting. The timer Tstart continues counting until reaching a predetermined value (kTIMELIMIT) for determining whether or not the engine coolant temperature is saturated. When the timer Tstart becomes larger than a predetermined value (kTIMELIMIT), it is determined whether or not the engine coolant temperature is equal to or higher than the warm-up determination temperature. If it is determined at time t1 that the engine coolant temperature is saturated, the idle up flag (xIDLUP) for increasing the idle rotation speed is turned on.

  When the idle up flag (xIDLUP) is turned on, the throttle valve 4 is gradually opened more than the set opening based on the engine coolant temperature, and the engine speed is gradually increased accordingly. As a result, the amount of heat generated by the engine 1 increases, and the engine coolant temperature begins to rise. When the engine coolant temperature becomes equal to or higher than the warm-up determination temperature (kTHWHIG) at time t2, the idle up flag (xIDLUP) for increasing the idle rotation speed is turned off and the timer Tstart is reset. When the idle up flag (xIDLUP) is turned off, the throttle valve 4 is gradually returned to the original opening so that the normal idling speed set based on the engine coolant temperature is reached. Return to the idle rotation speed.

  As described above, in the present embodiment, it is determined that the engine cooling water temperature is saturated when the engine cooling water temperature does not reach the warm-up temperature despite the time when the engine cooling water temperature has reached the warm-up temperature since the normal engine start. Then, the engine speed is increased by opening the throttle valve 4 by a predetermined opening from the set opening based on the engine coolant temperature, and the coolant temperature reaches the warm-up temperature.

  As a result, the engine coolant temperature can be quickly raised, so that learning control or the like that is started when the warm-up temperature is reached can be quickly executed.

[Third Embodiment]
When the engine cooling water temperature is saturated by using the heater during the warm-up operation in the idling operation, the failure diagnosis of the thermostat 11 for performing the failure diagnosis based on the engine cooling water temperature or the failure diagnosis of the water temperature sensor 12 is erroneously performed. There is a risk of misdiagnosis as a malfunction.

  Therefore, in this embodiment, when the saturation of the engine coolant temperature due to the heater operation is confirmed, in order to prevent erroneous diagnosis, the abnormality diagnosis of the thermostat 11 and the abnormality diagnosis of the water temperature sensor 12 are prohibited, thereby eliminating the above-mentioned inconvenience. It is to try.

  Hereinafter, this will be described in detail with reference to FIG.

  First, when the saturation of the engine cooling water temperature due to the heater operation is detected by the method of the first embodiment or the second embodiment and the throttle control for increasing the engine cooling water temperature is performed, in step 300, a thermostat is established. 11 trouble diagnosis and water temperature sensor 12 trouble diagnosis are prohibited. Next, at step 301, whether control for increasing the engine coolant temperature is being executed, that is, whether the throttle valve 4 is opened by a predetermined opening from the opening set based on the engine coolant temperature (xIDLUP). = ON).

  If the throttle valve 4 is opened by a predetermined opening from the opening set based on the engine coolant temperature, the determination is repeated. Thereafter, when the control to open the throttle valve 4 by a predetermined opening is completed (xIDLUP = OFF), the process proceeds to step 302, and the failure diagnosis prohibition of the thermostat 11 and the water temperature sensor 12 is canceled. Thereby, when the engine cooling water temperature is saturated by the heater operation, it is possible to prevent the erroneous determination of the thermostat 11 and the water temperature sensor 12 that occur because the engine cooling water temperature does not rise.

  In the present embodiment, both failure diagnoses are prohibited in order to prevent erroneous determination of the thermostat 11 and the water temperature sensor 12, but not limited to this method, either one may be prohibited.

[Fourth Embodiment]
The engine cooling water temperature saturation that occurs during the warm-up operation in the idle operation is caused by the fact that the heat of the engine cooling water is taken away by the operation of the heater and the engine cooling water due to the open failure of the thermostat 11. Is caused by being cooled by flowing into the radiator 9.

  Therefore, in the present embodiment, when the engine coolant temperature is saturated, it is identified whether the cause of the saturation is due to the heater operation or the open failure of the thermostat. The identification is that when the engine coolant temperature rises for a predetermined time when the engine coolant temperature is saturated and the engine coolant temperature rises, it is determined that there is no open failure of the thermostat. If the water temperature does not increase, it is determined by determining that the thermostat is open.

  The present embodiment will be described in detail with reference to FIG.

  When the saturation of the engine coolant temperature is detected by the method of the first embodiment or the second embodiment and the throttle control for increasing the engine coolant temperature is performed, first, in step 400, the thermostat 11 has failed. As described above, the temporary failure determination flag (xFAIL1) of the thermostat 11 is turned on. Next, the routine proceeds to step 401, where the temporary determination continuation timer Tfail for counting the elapsed time since turning on the idle up flag (xIDLUP) is reset. In step 402, the throttle valve 4 is opened by a predetermined opening, the idle rotation speed of the engine 1 is increased, and the engine coolant temperature is raised. Here, the predetermined opening degree of the throttle valve 4 is larger than the opening degree of the throttle valve 4 set so as to be the target idle rotation speed when the engine cooling water temperature is saturated due to the heat deprived by the heater. By opening the valve, the opening is set such that the engine coolant temperature reaches the warm-up temperature. When the throttle valve 4 is opened by a predetermined opening in step 402, the process proceeds to step 403, and it is determined whether or not the engine coolant temperature thw has been warmed up.

  When the engine coolant temperature thw is equal to or lower than the warm-up temperature kTHWHIG in step 403, the process proceeds to step 404 and the temporary determination continuation timer Tfail1 is counted up. In step 405, it is determined whether or not the temporary determination continuation timer Tfail1 has elapsed a predetermined time (kFAIL1). This predetermined time (kFAIL1) is the engine operated by the heater when the control is performed to open the throttle valve 4 beyond the opening set based on the engine coolant temperature in order to increase the saturated engine coolant temperature. If the cooling water temperature is saturated, it is set to a time sufficient to reach the warm-up temperature. If the provisional determination continuation timer Tfalt is equal to or shorter than the predetermined time kFAIL1, the process returns to step 403 in order to continue the provisional failure determination of the thermostat 11. Further, if the temporary determination continuation timer Tfail is equal to or longer than the predetermined time kFAIL1, the process proceeds to step 406, where it is determined that the thermostat 11 has failed.

  If the engine coolant temperature has reached the warm-up temperature in step 403, or if it is determined in step 406 that the thermostat 11 has failed, the process proceeds to step 407 and the provisional failure determination of the thermostat 11 is terminated. When the tentative failure determination is finished, the routine proceeds to step 408, where the opening of the throttle valve 4 is returned to the original value so that the idle rotation speed set by the engine coolant temperature is reached. Thereafter, the process proceeds to step 409 to reset the temporary determination continuation timer Tfail1. By executing this flowchart, when the engine coolant temperature is saturated, it can be determined whether it is caused by the heater operation or caused by the open failure of the thermostat.

  In this embodiment, the provisional determination continuation timer Tfail1 is measured, and it is determined whether or not the predetermined time (kFAIL1) is exceeded, but the failure of the thermostat 11 is determined. However, the engine after the throttle valve is opened is determined. The failure of the thermostat 11 may be determined by estimating the coolant temperature from the amount of heat generated inside and comparing it with the coolant temperature detected by the coolant temperature sensor 12.

  FIG. 11 is an example in which it is determined in the fourth embodiment that the saturation of the engine coolant temperature is caused by the heater operation. First, the throttle opening is set based on the engine coolant temperature shown in FIG. When the engine coolant temperature becomes equal to or higher than a predetermined coolant temperature (kTHWLOW) at time t1, the timer Tsat starts counting to determine whether the engine coolant temperature is saturated near the warm-up temperature. At time t2, the engine coolant temperature does not rise and the timer Tsat continues to be counted, so that the timer Tsat becomes equal to or greater than a predetermined value (kTIMELIMIT). Thereby, it is determined that the engine coolant temperature is saturated, and the idle up flag (xIDLUP) is turned on. Here, temporary failure determination (xFAIL1) of the thermostat 11 is turned on, and the temporary determination continuation timer Tfail1 is counted up. When the idle up flag (xIDLUP) is turned on, the throttle valve is gradually opened to a predetermined opening, and the engine speed is gradually increased accordingly. As a result, the amount of heat generated inside the engine increases and the coolant temperature begins to rise.

  When the engine coolant temperature becomes equal to or higher than the warm-up determination temperature (kTHWHIGH), the idle up flag for increasing the idle rotation speed and the timer Tsat are turned off. At this time, since the temporary determination continuation timer Tfail1 for determining the failure of the thermostat 11 has reached the warm-up temperature before the predetermined time (kFAIL1) for determining that the thermostat 11 has failed, the thermostat 11 has failed to open. Judge that it is not. When the failure determination of the thermostat 11 is finished, the failure temporary determination (xFAIL1) and the temporary determination continuation timer Tfail1 are turned off. When the idle up flag (xIDLUP) is turned off, the throttle valve 4 is gradually returned to the original opening degree so that the idle rotation speed set based on the engine coolant temperature is reached. From the above, it can be determined that the cause of the saturation of the engine coolant temperature is not due to the open failure of the thermostat 11 but to the heat deprived by the heater operation.

  Next, FIG. 12 shows an example when it is determined in the fourth embodiment that the saturation of the engine coolant temperature is due to an open failure of the thermostat 11. The difference from FIG. 11 is that the provisional determination continuation timer Tfail1 for determining the failure of the thermostat 11 has exceeded the predetermined time (kFAIL1) for determining that the thermostat 11 has failed. It is that this determination was made.

  At time t3, the counted temporary determination continuation timer Tfail1 is equal to or longer than a predetermined time (kFAIL1) in which it is determined that the thermostat 11 has failed. Therefore, it is determined that the thermostat 11 has failed. When the failure main determination (xFAIL2) of the thermostat 11 is turned on, the idle up flag (xIDLUP), the failure temporary determination (xFAIL1), and the temporary determination continuation timer Tfail1 are turned off. When the idle up flag (xIDLUP) is turned off, the throttle valve 4 is gradually returned to the original opening so that the idling speed set based on the engine coolant temperature is reached, and the engine speed is changed to the original idling speed. Return to. Thereby, it can be determined that the cause of the saturation of the engine coolant temperature is not due to the heater operation but due to the open failure of the thermostat 11.

  As described above, in the first to fourth embodiments, whether or not the engine coolant temperature is saturated is determined by measuring the elapsed time and determining whether the engine coolant temperature is saturated or not. Judgment was performed. In addition to this determination, as a method of determining whether or not the engine coolant temperature has been saturated, it may be determined whether or not the warm-up determination temperature is reached by looking at the amount of change in the engine coolant temperature. For example, when the engine coolant temperature is equal to or lower than the warm-up determination temperature and the change amount of the engine coolant temperature is smaller than a predetermined amount, it may be determined that the engine coolant temperature does not reach the warm-up determination temperature. Further, by estimating the engine coolant temperature from the engine coolant temperature and the amount of change in the engine coolant temperature, it may be determined that the engine coolant temperature does not reach the warm-up determination temperature even if more time elapses.

  Moreover, although the warm-up determination temperature is set to 80 ° C., since there is a variation in the warm-up temperature for each model, any temperature may be used as long as the warm-up can be determined according to the model. Similarly, the saturation predetermined temperature is set to 75 ° C., but any temperature may be set as long as it is equal to or lower than the warm-up determination temperature.

  Further, although the method of increasing the engine coolant temperature is performed by adjusting the opening degree of the throttle valve, it may be performed by adjusting the lift amount of the intake valve.

1 is a schematic diagram of an engine control system employing an internal combustion engine idle speed control device of the present invention. It is a time chart when the engine coolant temperature is saturated. It is a map which prescribes | regulates the determination value for determining whether the engine cooling water temperature was saturated based on external temperature and the water temperature at the time of starting. It is a flowchart for determining whether the engine coolant temperature is saturated in the first embodiment and heating the coolant. It is a flowchart which heats the cooling water of an engine in 1st Embodiment. It is a time chart which shows operation | movement of 1st Embodiment. It is a flowchart for determining whether the engine coolant temperature is saturated in the second embodiment and heating the coolant. It is a time chart which shows operation | movement of 2nd Embodiment. It is a flowchart which prohibits each failure diagnosis of a thermostat and a water temperature sensor, when heating the cooling water of an engine in 3rd Embodiment. 14 is a flowchart for identifying whether the engine coolant temperature is saturated due to heater operation or the engine coolant temperature is saturated due to a thermostat opening failure when heating the engine coolant temperature in the fourth embodiment. In 4th Embodiment, it is a time chart when saturation of engine cooling water temperature arises by heater operation | movement. In 4th Embodiment, it is a time chart when the saturation of engine cooling water temperature arises by the open failure of a thermostat.

Explanation of symbols

1 Engine 2 Engine control unit (ECU)
DESCRIPTION OF SYMBOLS 3 Intake passage 4 Throttle valve 5 Engine speed sensor 6 Shift position sensor 7 Intake temperature sensor 8 Idle determination sensor 9 Radiator 10 Cooling water passage 11 Thermostat 12 Cooling water temperature sensor 13 Air-conditioner control device 14 Air-conditioner ventilation passage 15 Air-conditioner ventilation fan 16 Evaporator 17 Air conditioner mix damper 18 Heater core 19 Air conditioner outlet

Claims (10)

In an idling engine speed control device for an internal combustion engine comprising an idling engine speed control means for controlling an idling engine speed from a cold start to completion of warm-up,
Heater operation determining means for determining whether the heater is operating;
Determination means for determining whether or not the cooling water temperature of the internal combustion engine is saturated below a warm-up temperature,
In the warm-up operation by the idle rotation speed control means, when the heater operation determining means determines the heater operation, and the determination means determines that the cooling water temperature of the internal combustion engine is saturated, the internal combustion engine An idling speed control device for an internal combustion engine, comprising: a cooling water temperature raising means for raising the cooling water temperature of the engine. Comprising a time measuring means for counting the duration when the cooling water temperature of the internal combustion engine is in a predetermined temperature range below the warm-up temperature,
The determination means determines whether the internal combustion engine has a continuous time after the cooling water temperature counted by the timing means reaches a predetermined temperature range lower than the warm-up temperature, when the duration exceeds a predetermined value for determining that the cooling water temperature is saturated. 2. The idle rotation speed control device for an internal combustion engine according to claim 1, wherein the cooling water temperature is determined to be saturated. Comprising time measuring means for counting an elapsed time since the internal combustion engine was started,
The determining means determines that the cooling water temperature of the internal combustion engine is saturated when the elapsed time counted from the engine starting time counted by the time measuring means becomes equal to or greater than a predetermined value for determining that the cooling water temperature is saturated. 2. The idle rotation speed control device for an internal combustion engine according to claim 1, wherein 4. The predetermined value for determining that the cooling water temperature is saturated is calculated based on a starting water temperature and / or an outside air temperature of the internal combustion engine. Idling rotation speed control device for internal combustion engine. A cooling water temperature change amount calculating means for calculating a change amount of the cooling water temperature of the internal combustion engine,
2. The determination unit according to claim 1, wherein the determination unit determines that the cooling water temperature of the internal combustion engine is saturated when the cooling water temperature is lower than a warm-up determination temperature and the change amount is small by the cooling water temperature change amount calculation unit. The internal-combustion-engine idle rotational speed control apparatus of description. The idle temperature of the internal combustion engine according to any one of claims 1 to 5, wherein the cooling water temperature increasing means increases the cooling water temperature of the internal combustion engine by increasing an idle rotation speed of the internal combustion engine. Rotational speed control device. The internal combustion engine according to any one of claims 1 to 6, wherein in the warm-up operation by the idle speed control means, the idle switch is turned on and the engine speed is equal to or lower than a predetermined speed. Idle speed control device. A thermostat that opens and closes a passage through which cooling water circulates between the internal combustion engine and the radiator, and / or a failure diagnosis prohibiting unit that prohibits failure diagnosis of a cooling water temperature detecting unit that measures the cooling water temperature of the internal combustion engine,
The failure diagnosis of the thermostat and / or the cooling water temperature detecting means is prohibited by the failure diagnosis prohibiting means when the determining means determines that the cooling water temperature of the internal combustion engine is saturated. 7. An idle rotation speed control device for an internal combustion engine according to any one of claims 7 to 10. A thermostat failure determining means for determining a failure of a thermostat provided to open and close a passage through which the coolant temperature circulates between the internal combustion engine and the radiator;
A timing means for counting an elapsed time since it is determined that the cooling water temperature of the internal combustion engine is saturated by the determining means, and the cooling water temperature increasing means starts to increase the cooling water temperature;
Although the thermostat failure determination means increases the cooling water temperature by the cooling water temperature increase means, the cooling water temperature of the internal combustion engine does not reach the warm-up temperature, and the elapsed time counted by the time counting means 8. The idling speed control device for an internal combustion engine according to claim 1, wherein when the temperature exceeds a predetermined value, it is determined that the thermostat is in failure. A cooling water temperature estimating means for estimating the cooling water temperature of the internal combustion engine based on the calorific value generated by the internal combustion engine;
The failure determination means of the thermostat determines the failure of the thermostat by comparing the estimated cooling water temperature calculated by the cooling water temperature estimation means and the cooling water temperature detected by the cooling water temperature detection means. The idle speed control apparatus for an internal combustion engine according to claim 9.

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