JP4378641B2 - Throttle control device for internal combustion engine - Google Patents

Description

  The present invention relates to a throttle control device for an internal combustion engine in which a throttle valve provided in an intake pipe of the internal combustion engine is driven to open and close by an electric actuator such as a motor.

  In an extremely low temperature environment, moisture contained in the intake air in the intake pipe (for example, moisture contained in the blow-by gas introduced into the intake pipe) freezes during operation of the internal combustion engine, and the throttle valve is frozen. There is a possibility that the throttle valve cannot be operated normally due to this icing.

Therefore, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2000-320348), even if the throttle opening fluctuates, such as when the internal combustion engine is started or during fuel cut control, the output torque is not much. There is a type in which the throttle valve is swung to eliminate icing of the throttle valve in an operating state that does not affect the operation.
JP 2000-320348 A (2nd page, etc.)

  However, as described in Patent Document 1, in the technique of swinging the throttle valve during fuel cut control or the like to eliminate icing of the throttle valve, when the ice is firmly attached to the throttle valve, the throttle valve It is difficult to remove the ice adhering to the throttle valve even if it is swung. For this reason, the following problems may occur.

  According to the study by the present inventors, the temperature in the intake pipe after the internal combustion engine stops is increased by the residual heat of the internal combustion engine and then decreases and approaches the outside air temperature. As shown in FIG. 10 (when the throttle body is arranged horizontally) and when the throttle valve 1 freezes during operation of the internal combustion engine, the internal combustion engine is stopped. Later, the ice adhering to the throttle valve 1 melts into water due to the temperature rise in the intake pipe 2, and the water becomes between the throttle valve 1 and the inner wall of the throttle body 3 (inner wall of the intake pipe 2). In a state where the air has accumulated in the air, it may freeze again due to a temperature drop in the intake pipe 2. As a result, there is a possibility that the throttle valve 1 freezes on the inner wall of the throttle body 3 and the throttle valve 1 cannot operate normally at the next start.

  Further, as in the above-described Patent Document 1, in the technique of swinging the throttle valve to eliminate the freezing of the throttle valve, ice blocks adhering to the throttle valve are struck against the inner wall of the throttle body. The drive mechanism (gear, etc.) and the throttle body may be damaged and durability may be reduced, or the collision noise of ice blocks may be heard as noise by the driver.

  The present invention has been made in consideration of these circumstances. Accordingly, the object of the present invention is to prevent the occurrence of noise due to the durability of the throttle device and the noise caused by the collision of ice blocks, and the throttle valve at the start-up. An object of the present invention is to provide a throttle control device for an internal combustion engine that can prevent icing and can operate a throttle valve normally from the start.

In order to achieve the above object, an invention according to claim 1 is directed to an internal combustion engine throttle control device in which a throttle valve provided in an intake pipe of an internal combustion engine is driven to open and close by an electric actuator such as a motor or a solenoid. The first feature is that the throttle valve is driven to open and close at a predetermined time after the internal combustion engine is stopped by the throttle opening / closing control means . Further, the ice adhering to the throttle valve after the internal combustion engine is stopped melts into water. The second feature is that the melting time is determined by the melting time determining means, the melting time is determined as the predetermined time, and the throttle valve is driven to open and close.

In this way, even if the throttle valve is frozen immediately after the internal combustion engine stops, the temperature in the intake pipe rises due to the residual heat of the internal combustion engine after the internal combustion engine stops, and the ice in the throttle valve gradually melts. because going to, during periods of ice adhering to the throttle valve after the stop of the internal combustion engine becomes substantially water melted easily shake off the water adhering to the throttle valve by opening and closing the throttle valve be able to. Therefore, even if the temperature in the intake pipe subsequently drops below the freezing point while the internal combustion engine is stopped, the throttle valve can be prevented from freezing, and the throttle valve can be operated normally at the next start. it can. In addition, unlike conventional models, ice blocks adhering to the throttle valve are no longer struck against the inner wall of the intake pipe (inner wall of the throttle body), preventing damage to the throttle device, lowering durability, and noise generation due to collision noise of ice blocks. can do.

In this case, as in the second feature , the melting time determining means determines the melting time when the ice adhering to the throttle valve melts to become water after the internal combustion engine is stopped, and the throttle valve is turned on at this melting time. if so as to open and close the drive, it can be ice adhering to the throttle valve after the stop of the internal combustion engine for opening and closing a reliable throttle valve melting time obtained by melting in water.

In general, the melting time when the ice block adhering to the throttle valve melts to become water after the internal combustion engine is stopped depends on the temperature of the internal combustion engine immediately after the stop, which affects the temperature rise behavior in the intake pipe after the internal combustion engine stops. for that varies with temperature, as in claim 2, the outside air temperature, intake air temperature, water temperature, good and so as to determine the melting time based on at least one of the oil temperature (instead of the intake air temperature is ambient temperature The water temperature and the oil temperature are the temperature information of the internal combustion engine). In this way, the melting time can be accurately determined.

Further, as in claim 3 , the throttle valve may be driven to open and close a plurality of times at a predetermined time after the internal combustion engine is stopped. In this way, even when the throttle valve is driven to open and close only once, the water adhering to the throttle valve cannot be shaken off, the water adhering to the throttle valve is driven by opening and closing the throttle valve a plurality of times. Can be reliably shaken off.

In this case, as described in claim 4, the number of times of driving when opening and closing the throttle valve at a predetermined time after the internal combustion engine is stopped is set based on at least one of the outside air temperature, the intake air temperature, the water temperature, and the oil temperature. Good. In this way, the number of times the throttle valve is driven to an appropriate value in response to changes in the melting speed and the amount of melted water according to the outside air temperature (intake air temperature) and the internal combustion engine temperature (water temperature, oil temperature). Therefore, it is possible to reliably shake off the water adhering to the throttle valve without unnecessarily increasing the number of times the throttle valve is driven.

Furthermore, as according to claim 5, after opening or opening and closing the throttle valve to a predetermined time after stop of the internal combustion engine closes the throttle valve, the predetermined time for switching to a closed from an open or opening and closing the throttle valve, melting it may be with the melting time determined by the timing determining means. In this way, the water attached to the throttle valve can be easily drained by opening the throttle valve until the ice adhering to the throttle valve melts into water after the internal combustion engine stops. Yes (or the water attached to the throttle valve can be easily shaken off by opening / closing the throttle valve).

In this case, as in claim 5, the predetermined time for switching to a closed from an open or opening and closing the throttle valve, if the melting time was determined by melt-timing determining means, adhering to the throttle valve after the stop of the internal combustion engine The throttle valve can be reliably opened or opened until the melting time when the ice melts into water. Further, as in claim 6 , if the melting time is determined based on at least one of the outside air temperature, the intake air temperature, the water temperature, and the oil temperature, the melting time can be accurately determined.

  Hereinafter, the best mode for carrying out the present invention will be described using two Examples 1 and 2.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An intake pipe 12 of an engine 11, which is an internal combustion engine, has a throttle valve 14 whose opening is adjusted by an electric actuator such as a motor 13, and a throttle opening sensor 15 that detects the opening (throttle opening) of the throttle valve 14. And are provided. The throttle valve 14 returns to an initial value (for example, an opener position set slightly open from the fully closed position) by a return spring or the like when the motor 13 is turned off. ing. In the first embodiment, as shown in FIG. 3, the throttle body 10 incorporating the throttle valve 14 has a vertical arrangement in which the throttle body 10 is arranged in the vertical direction.

  Further, as shown in FIG. 1, a surge tank 16 is provided on the downstream side of the throttle valve 14, and an intake pipe pressure sensor 17 for detecting the intake pipe pressure and an intake pipe for detecting the intake air temperature are provided in the surge tank 16. An air temperature sensor 18 is provided. The surge tank 16 is connected to an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 19 of each cylinder. Yes. A spark plug 21 is attached to each cylinder of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each spark plug 21.

  Further, a first blow-by gas pipe 22 for connecting blow-by gas (gas that escapes from the gap between the cylinder and the piston to the crankcase) into the intake system is connected between the cylinder head of the engine 11 and the surge tank 16. A second blow-by gas pipe 23 is connected between the cylinder head of the engine 11 and the upstream side of the throttle valve 14 in the intake pipe 12.

  A cooling water temperature sensor 24 that detects the cooling water temperature and a crank angle sensor (not shown) that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. ing.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 25. The ECU 25 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 20 according to the engine operating state. The ignition timing of the spark plug 21 is controlled, and the motor 13 of the throttle valve 14 is controlled so that the actual throttle opening matches the target throttle opening.

  By the way, in a cryogenic environment, the moisture contained in the intake air in the intake pipe 12 (for example, the moisture contained in the blow-by gas introduced into the intake pipe 12) freezes during engine operation, and the throttle valve 14 Freezing may occur. If icing occurs in the throttle valve 14 during engine operation, the ice adhering to the throttle valve 14 is melted due to the temperature rise in the intake pipe 12 (in the throttle body 10) due to the residual heat of the engine 11 after the engine is stopped. When the water accumulates between the throttle valve 14 and the inner wall of the intake pipe 12 (inner wall of the throttle body 10) and freezes again due to a temperature drop in the intake pipe 12, the throttle valve 14 There is a possibility that the throttle valve 14 will not be able to operate normally at the next start because it freezes on the inner wall of the intake pipe 12 (inner wall of the throttle body 10).

  As a countermeasure against this, the ECU 25 executes the throttle opening / closing control after the engine stop as follows by executing the throttle opening / closing control program after the engine stop of FIGS. 4 and 5 described later. In order to execute the throttle opening / closing control after the engine is stopped, the energization to the ECU 25 is continued for a while after the IG switch 26 (ignition switch) is turned off.

  As shown in FIG. 2, after the IG switch 26 is turned off and the engine 11 is stopped, when a predetermined execution condition for throttle opening / closing control after engine stop is satisfied, an elapsed time after the IG switch is turned off is a predetermined melting time. It is determined whether or not it is time to melt the ice adhering to the throttle valve 14 due to the temperature rise in the intake pipe 12 after the engine is stopped, to melt into water by determining whether or not the determination value fs (THAmin) has been exceeded. To do.

  Then, at time t1 when it is determined that the melting time has come, throttle valve opening control is started. In this throttle valve opening control, the target throttle opening degree TANG is gradually increased and finally maintained at the maximum value kTANGHI (for example, the fully opened position), so that the actual throttle opening degree is gradually increased and finally the maximum value. Maintain at kTANGHI.

  Thereafter, at the time t2 when the execution time of the throttle valve opening control reaches a predetermined value kTOPN, the throttle valve opening control is terminated and the throttle valve closing control is started. In this throttle valve closing control, the actual throttle opening is gradually decreased by gradually decreasing the target throttle opening TANG and turning off the power supply to the motor 13 of the throttle valve 14 before the initial value kTANGLOW (for example, the opener position). And finally maintain the initial value kTANGLOW by a return spring or the like.

Thereafter, at the time t3 when the execution time of the throttle valve closing control reaches the predetermined value kTCLS, the throttle valve closing control is terminated and the throttle valve opening control is started.
In this manner, before the elapsed time after the IG switch is turned off reaches the predetermined end determination value fe (THAmin), the throttle valve opening control and the throttle valve closing control are alternately executed to drive the throttle valve 14 to open and close. The processing is repeated, and at time t4 when the elapsed time after the IG switch is turned off reaches the end determination value fe (THAmin), the throttle opening / closing control is ended after the engine is stopped.

  As a result, as shown in FIG. 3, even when the ice is firmly attached to the throttle valve 14, the ice attached to the throttle valve 14 is melted due to the temperature rise in the intake pipe 12 after the engine is stopped. At the time of melting into water, the throttle valve 14 can be driven to open and close, and the water adhering to the throttle valve 14 can be easily shaken off. As a result, it is possible to prevent the throttle valve 14 from icing when the temperature in the intake pipe 12 subsequently decreases, and the throttle valve 14 can reliably operate normally at the next start.

Hereinafter, the processing contents of the throttle opening / closing control program after engine stop of FIGS. 4 and 5 executed by the ECU 25 will be described.
The throttle opening / closing control program after engine stop in FIGS. 4 and 5 is executed after the engine stops (after the IG switch 26 is turned off), and plays a role as a throttle opening / closing control means after engine stop in the claims. When this program is started, first, in step 101, it is determined whether or not an execution condition for throttle opening / closing control after engine stop is satisfied. Here, the execution condition of the throttle opening / closing control after the engine stops is, for example, that both the following conditions (1) and (2) are satisfied.

(1) The minimum intake air temperature value THAmin (the minimum value of the intake air temperature detected by the intake air temperature sensor 18 during a predetermined period before the engine is stopped) is equal to or less than a predetermined freezing determination value kTHA.
(2) The battery voltage is equal to or higher than the predetermined value kVB. The condition (1) above is a condition for determining whether or not the water is in a cold state, and the condition (2) is that the engine is stopped. Is a condition for determining whether or not there is a battery capacity necessary to open and close the throttle valve 14.

  If both of the above conditions (1) and (2) are satisfied, the throttle opening / closing control execution condition is satisfied after the engine stops, but if either of the above conditions (1) and (2) is not satisfied, Then, the execution condition of the throttle opening / closing control is not satisfied after the engine is stopped.

  If it is determined in step 101 that the execution condition of the throttle opening / closing control after engine stop is not satisfied, the process proceeds to step 121 in FIG. While energizing the motor 13 of the throttle valve 14 is maintained in the OFF state, the target throttle opening degree TANG is maintained at the initial value kTANGLOW, and this program is terminated.

  On the other hand, if it is determined in step 101 of FIG. 4 that the conditions for executing the throttle opening / closing control after engine stop are satisfied, the processing relating to the throttle opening / closing control after engine stop after step 102 is executed as follows. To do. First, at step 102, the throttle opening / closing switching flag XSOC is set to "1" which means throttle valve opening control.

  Thereafter, the process proceeds to step 103, the count value of an elapsed time counter COFF after IG OFF that counts the elapsed time after the IG switch is turned off (after engine stop) is counted up, and then the process proceeds to step 104, where the elapsed time counter after the IG off. Depending on whether or not the COFF count value exceeds the melting time judgment value fs (THAmin), the melting time when the ice adhering to the throttle valve 14 is melted to become water due to the temperature rise in the intake pipe 12 after the engine is stopped. It is determined whether or not.

  Here, the melting time determination value fs (THAmin) is a value corresponding to the time required from the time when the IG switch is turned off until the ice adhering to the throttle valve 14 melts to become water, and the minimum intake air temperature value THAmin. Is set by a map or a mathematical expression or the like. The processing in step 104 serves as melting time determination means in the claims.

  If it is determined in step 104 that the count value of the elapsed time counter COFF after IG OFF is equal to or less than the melting time determination value fs (THAmin), it is determined that the melting time is not yet reached, and the process proceeds to step 105. While maintaining the target throttle opening degree TANG at the initial value kTANGLOW, the process returns to step 103 and the process of counting up the elapsed time counter COFF after IG OFF is repeated.

  Thereafter, when it is determined in step 104 that the count value of the elapsed time counter COFF after IG OFF exceeds the melting time determination value fs (THAmin), the ice adhering to the throttle valve 14 is melted to become water. When it is determined that the melting time has come, the routine proceeds to step 106, where it is determined whether or not the throttle opening / closing switching flag XSOC is set to "1".

  If it is determined in step 106 that the throttle opening / closing switching flag XSOC is set to “1”, the throttle valve opening control is executed as follows. First, in step 107, the count value of a valve opening control time counter COPN that counts the execution time of throttle valve opening control is counted up, and the count value of a valve closing control time counter CCLS described later is reset to “0”.

Thereafter, the routine proceeds to step 108, where it is determined whether or not the count value of the valve opening control time counter COPN is smaller than the predetermined value kTOPN, and it is determined that the count value of the valve opening control time counter COPN is smaller than the predetermined value kTOPN. If YES in step 109, the flow advances to step 109 to increase the temporary target throttle opening degree TTANG by a predetermined value ΔOPN.
TTANG = TTANG + ΔOPN

Thereafter, the routine proceeds to step 110, where it is determined whether or not the temporary target throttle opening degree TTANG is smaller than the maximum value kTANGHI, and when it is determined that the temporary target throttle opening degree TTANG is smaller than the maximum value kTANGHI. In step 112, the target throttle opening degree TANG is set to the temporary target throttle opening degree TTANG.
TANG = TTANG

Thereafter, when it is determined in step 110 that the temporary target throttle opening degree TTANG is equal to or larger than the maximum value kTANGHI, the routine proceeds to step 111, where the temporary target throttle opening degree TTANG is guarded with the maximum value kTANGHI. (TTANG = kTANGHI), the process proceeds to step 112, where the target throttle opening degree TANG is set to the temporary target throttle opening degree TTANG.
TANG = TTANG

  Through the processing of these steps 108 to 112, the target throttle opening degree TANG is increased by a predetermined value ΔOPN and finally maintained at the maximum value kTANGHI, so that the actual throttle opening degree is increased by a predetermined value ΔOPN and finally The maximum value is maintained at kTANGHI.

  Thereafter, when it is determined in step 108 that the count value of the valve opening control time counter COPN is equal to or greater than the predetermined value kTOPN, the routine proceeds to step 113, where the throttle opening / closing switching flag XSOC is the throttle valve closing control. Reset to “0”.

  Thereafter, when it is determined in step 106 that the throttle opening / closing switching flag XSOC is “0”, the throttle valve closing control is executed as follows. First, in step 114 of FIG. 5, the count value of the valve closing control time counter CCLS that counts the execution time of the throttle valve closing control is counted up, and the count value of the valve opening control time counter COPN is reset to “0”. .

Thereafter, the routine proceeds to step 115, where it is determined whether or not the count value of the valve closing control time counter CCLS is smaller than the predetermined value kTCLS, and it is determined that the count value of the valve closing control time counter CCLS is smaller than the predetermined value kTCLS. If YES in step 116, the flow advances to step 116 to decrease the target throttle opening degree TANG by a predetermined value ΔCLS.
TANG = TANG-ΔCLS

  After that, the routine proceeds to step 117, where it is determined whether or not the target throttle opening degree TANG is equal to or smaller than a value obtained by adding a predetermined value ΔOFF to the initial value kTANGLOW, and the target throttle opening degree TANG adds the predetermined value ΔOFF to the initial value kTANGLOW. When it is determined that the value is equal to or smaller than the predetermined value, the routine proceeds to step 118 where the power supply to the motor 13 of the throttle valve 14 is turned off and the target throttle opening degree TANG is set to the initial value kTANGLOW.

  Through the processing of these steps 116 to 118, the actual throttle opening is gradually decreased by gradually decreasing the target throttle opening TANG and turning off the power supply to the motor 13 of the throttle valve 14 before the initial value kTANGLOW. Finally, the initial value kTANGLOW is maintained by a return spring or the like.

  Thereafter, when it is determined in step 115 that the count value of the valve closing control time counter CCLS is equal to or greater than the predetermined value kTCLS, the routine proceeds to step 119, where the throttle opening / closing switching flag XSOC is set to “1”.

  Until the count value of the elapsed time counter COFF after IG OFF is determined to be equal to or greater than the end determination value fe (THAmin) in the next step 120, the processing in steps 103 to 119 is repeated to perform the throttle valve opening control. Throttle valve closing control is executed alternately. Here, the end determination value fe (THAmin) is a determination value for setting the number of times the throttle valve 14 is driven, and is set by a map or a mathematical formula or the like according to the minimum intake air temperature value THAmin. In the first embodiment, the end determination value fe (THAmin) is set so that the throttle valve 14 is driven to open and close twice or more.

  Thereafter, when it is determined in step 120 that the count value of the elapsed time counter COFF after IG OFF is equal to or greater than the end determination value fe (THAmin), the process proceeds to step 121 and the energization of the motor 13 of the throttle valve 14 is turned off. At the same time, the target throttle opening TANG is set to the initial value kTANGLOW, and this program is terminated.

  In the first embodiment described above, depending on whether or not the elapsed time after the IG switch is turned off exceeds the melting timing determination value fs (THAmin), it adheres to the throttle valve 14 due to the temperature rise in the intake pipe 12 after the engine stops. It is determined whether or not it is time to melt the ice that has been melted to become water, and when the melting time comes, the throttle valve opening control and the throttle valve closing control are executed alternately, and the throttle valve 14 is turned on. Open / close drive. Thereby, even when the throttle valve 14 is frozen, the water attached to the throttle valve can be easily shaken off by opening and closing the throttle valve 14 at the melting time after the engine is stopped. Therefore, even if the temperature in the intake pipe 12 subsequently drops below the freezing point while the engine is stopped, the throttle valve 14 can be prevented from icing, and the throttle valve 14 can be reliably operated at the next start. It can be operated. In addition, unlike the prior art, ice blocks adhering to the throttle valve 14 are no longer struck against the inner wall of the intake pipe 12 (inner wall of the throttle body 10). Occurrence can be prevented.

  Further, in the first embodiment, the intake air temperature is minimized in consideration of the change in the melting time when the ice attached to the throttle valve 14 melts to become water after the engine stops according to the outside air temperature (intake air temperature). Since the melting time is determined using the melting time determination value fs (THAmin) set according to the value THAmin, the melting time that varies depending on the outside air temperature (intake air temperature) can be determined with high accuracy.

  In the first embodiment, since the throttle valve 14 is driven to open and close twice or more during the melting time after the engine is stopped, the water adhering to the throttle valve 14 can be driven only by opening and closing the throttle valve 14 once. Even if the water cannot be completely shaken off, the water attached to the throttle valve 14 can be reliably shaken off by opening and closing the throttle valve 14 twice or more. However, in the present invention, the throttle valve 14 may be opened and closed only once, and even in this case, a certain degree of anti-icing effect can be obtained.

  Further, in the first embodiment, by setting an end determination value fe (THAmin) of the throttle opening / closing control after engine stop according to the minimum intake air temperature value THAmin, the throttle valve 14 is driven to open / close according to the minimum intake air temperature value THAmin. Since the number of times is set, the number of times that the throttle valve 14 is driven can be set to an appropriate number in response to the change in the melting speed of the ice and the amount of melted water according to the outside air temperature (intake air temperature). The water adhering to the throttle valve 14 can be reliably shaken off without unnecessarily increasing the number of times the throttle valve 14 is driven.

The number of times the throttle valve 14 is driven may be set based on one or more of the outside air temperature, the intake air temperature, the water temperature, and the oil temperature .

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, as shown in FIG. 7, the throttle body 10 incorporating the throttle valve 14 has a horizontal arrangement in which the throttle body 10 is arranged in a substantially horizontal direction. Other system configurations are substantially the same as those of the first embodiment.

  The ECU 25 executes the throttle opening / closing control program after engine stop in FIG. 8 described later, thereby executing the throttle opening / closing control after engine stop as follows. As shown in FIG. 6, the throttle valve opening control is started at time t1 when the IG switch 26 is turned off and the engine 11 is stopped. In this throttle valve opening control, the target throttle opening degree TANG is gradually increased and finally maintained at the maximum value kTANGHI, so that the actual throttle opening degree is gradually increased and finally maintained at the maximum value kTANGHI. In this case, the maximum value kTANGHI is set, for example, at a position where the throttle valve 14 is inclined with respect to the horizontal direction.

  Thereafter, the elapsed time after the IG switch is turned off exceeds the melting timing determination value fs (THAmin), and the ice adhering to the throttle valve 14 is melted into water by the temperature rise in the intake pipe 12 after the engine is stopped. At the time t2 when it is determined that the melting time is reached, the throttle valve opening control is terminated and the throttle valve closing control is started. In this throttle valve closing control, the actual throttle opening is gradually decreased by gradually decreasing the target throttle opening TANG and turning off the power supply to the motor 13 of the throttle valve 14 before the initial value kTANGLOW (for example, the opener position). And finally maintain the initial value kTANGLOW by a return spring or the like.

  Accordingly, as shown in FIG. 7, even when the throttle valve 14 is frozen, the ice adhering to the throttle valve 14 is melted to become water by the temperature rise in the intake pipe 12 after the engine is stopped. Until the time is reached, the throttle valve 14 is opened and maintained in the inclined posture, so that the water adhering to the throttle valve 14 can be easily poured off. As a result, it is possible to prevent the throttle valve 14 from icing when the temperature in the intake pipe 12 subsequently decreases, and the throttle valve 14 can reliably operate normally at the next start.

  Hereinafter, the processing content of the after-engine stop throttle opening / closing control program of FIG. 8 executed by the ECU 25 will be described. When this program is started, first, at step 201, it is determined whether or not an execution condition for throttle opening / closing control after engine stop is satisfied. The execution conditions for the throttle opening / closing control after engine stop are the same as the execution conditions for the throttle opening / closing control after engine stop described in the first embodiment.

  If it is determined in step 201 that the execution condition of the throttle opening / closing control after engine stop is not satisfied, the process proceeds to step 210 without executing the processing related to the throttle opening / closing control after engine stop after step 202, and the throttle valve 14 Is maintained in the OFF state, and the target throttle opening TANG is maintained at the initial value kTANGLOW, and this program is terminated.

On the other hand, if it is determined in step 201 that the conditions for executing the throttle opening / closing control after engine stop are satisfied, the processing related to the throttle opening / closing control after engine stop after step 202 is executed as follows. First, at step 202, the count value of the elapsed time counter COFF after IG OFF is counted up, and then the throttle valve opening control is executed as follows. First, in step 203, the temporary target throttle opening degree TTANG is increased by a predetermined value ΔOPN.
TTANG = TTANG + ΔOPN

After this, the routine proceeds to step 204, where it is determined whether or not the temporary target throttle opening degree TTANG is smaller than the maximum value kTANGHI, and when it is determined that the temporary target throttle opening degree TTANG is smaller than the maximum value kTANGHI. In step 206, the target throttle opening degree TANG is set to the temporary target throttle opening degree TTANG.
TANG = TTANG

Thereafter, when it is determined in step 204 that the temporary target throttle opening degree TTANG is equal to or larger than the maximum value kTANGHI, the process proceeds to step 205, and after the temporary target throttle opening degree TTANG is limited to the maximum value kTANGHI ( (TTANG = kTANGHI), the process proceeds to step 206, where the target throttle opening degree TANG is set to the temporary target throttle opening degree TTANG.
TANG = TTANG

  Through the processing of these steps 203 to 206, the target throttle opening TANG is increased by a predetermined value ΔOPN and finally maintained at the maximum value kTANGHI, so that the actual throttle opening is increased by a predetermined value ΔOPN and finally The maximum value is maintained at kTANGHI.

Thereafter, in step 207, it is determined whether or not the count value of the elapsed time counter COFF after IG off has exceeded the melting timing determination value fs (THAmin), and the count value of the elapsed time counter COFF after IG OFF is the melting timing determination value. When it is determined that fs (THAmin) has been exceeded, it is determined that it is time to melt the ice adhering to the throttle valve 14 to become water, and the throttle valve closing control is executed as follows. . First, at step 208, the target throttle opening degree TANG is decreased by a predetermined value ΔCLS.
TANG = TANG-ΔCLS

  Thereafter, the process proceeds to step 209, where it is determined whether or not the target throttle opening degree TANG is equal to or smaller than a value obtained by adding the predetermined value ΔOFF to the initial value kTANGLOW, and the target throttle opening degree TANG adds the predetermined value ΔOFF to the initial value kTANGLOW. When it is determined that the value is equal to or smaller than the predetermined value, the routine proceeds to step 210, where the power supply to the motor 13 of the throttle valve 14 is turned off, and the target throttle opening degree TANG is set to the initial value kTANGLOW.

  By the processing of these steps 208 to 210, the actual throttle opening is gradually decreased by gradually decreasing the target throttle opening TANG and turning off the power supply to the motor 13 of the throttle valve 14 before the minimum position kTANGLOW. Finally, the initial value kTANGLOW is maintained by a return spring or the like.

  In the second embodiment described above, the tilt valve 14 is opened and tilted until the melting time when the ice adhering to the throttle valve 14 melts to become water due to the temperature rise in the intake pipe 12 after the engine stops. Therefore, the water adhering to the throttle valve 14 can be easily poured off. As a result, it is possible to prevent the throttle valve 14 from icing when the temperature in the intake pipe 12 subsequently decreases, and the throttle valve 14 can reliably operate normally at the next start.

  In the second embodiment, the throttle valve 14 is opened and maintained in an inclined position until it is determined that the melting time is reached after the engine is stopped. However, the throttle valve 14 is opened and closed until it is determined that the melting time is determined after the engine is stopped. The driving process may be repeated.

  In each of the first and second embodiments, the melting time is determined based on the intake air temperature. However, the melting time is determined based on one or more of the outside air temperature, the intake air temperature, the water temperature, and the oil temperature. May be determined.

  Further, the throttle opening / closing control after the engine stop of the first embodiment may be applied to a system including a laterally arranged throttle body. Further, the throttle opening / closing control after the engine stop according to the second embodiment may be applied to a system including a vertically arranged throttle body. Furthermore, the present invention may be applied to a system configuration in which blow-by gas piping is omitted.

It is a schematic block diagram of the whole engine control system in Example 1 of this invention. 6 is a time chart for explaining an execution example of throttle opening / closing control after engine stop according to the first embodiment. It is a figure for demonstrating the anti-icing effect of the throttle valve of Example 1. FIG. 6 is a flowchart (part 1) illustrating a flow of processing of a throttle opening / closing control program after engine stop according to the first embodiment. 6 is a flowchart (part 2) illustrating a flow of processing of a throttle opening / closing control program after engine stop according to the first embodiment. 6 is a time chart for explaining an execution example of throttle opening / closing control after engine stop according to the second embodiment. It is a figure for demonstrating the anti-icing effect of the throttle valve of Example 2. FIG. It is a flowchart which shows the flow of a process of the throttle opening / closing control program after an engine stop of Example 2. FIG. It is a figure for demonstrating the mechanism of freezing of the throttle valve of the conventional vertical arrangement | positioning. It is a figure for demonstrating the mechanism of the freezing of the throttle valve of the conventional horizontal arrangement | positioning.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 13 ... Motor, 14 ... Throttle valve, 15 ... Throttle opening sensor, 18 ... Intake temperature sensor, 20 ... Fuel injection valve, 21 ... Spark plug, 25 ... ECU ( Throttle opening / closing control means after engine stop, melting time judging means), 26... IG switch

Claims (6)

In a throttle control device for an internal combustion engine that opens and closes a throttle valve provided in an intake pipe of the internal combustion engine with an electric actuator such as a motor,
A throttle opening / closing control means after engine stop for opening and closing the throttle valve at a predetermined time after the internal combustion engine is stopped ;
Melting time determination means for determining a melting time when ice adhering to the throttle valve melts to become water after the internal combustion engine is stopped,
The throttle control device for an internal combustion engine, wherein the predetermined time is a melting time determined by the melting time determination means . 2. The throttle control device for an internal combustion engine according to claim 1 , wherein the melting time determination means determines the melting time based on at least one of an outside air temperature, an intake air temperature, a water temperature, and an oil temperature. The throttle control device for an internal combustion engine according to claim 1 or 2 , wherein the throttle opening / closing control means after the engine is stopped opens and closes the throttle valve a plurality of times at the predetermined time. The throttle opening / closing control means after engine stop sets the number of times of driving when opening and closing the throttle valve at the predetermined time based on at least one of outside air temperature, intake air temperature, water temperature, and oil temperature. The throttle control device for an internal combustion engine according to claim 3 . In a throttle control device for an internal combustion engine that opens and closes a throttle valve provided in an intake pipe of the internal combustion engine with an electric actuator such as a motor,
A throttle opening / closing control means after engine stop for closing the throttle valve after opening or opening / closing the throttle valve until a predetermined time after the internal combustion engine is stopped ;
Melting time determination means for determining a melting time when ice adhering to the throttle valve melts to become water after the internal combustion engine is stopped,
The throttle control device for an internal combustion engine, wherein the predetermined time is a melting time determined by the melting time determination means . 6. The throttle control device for an internal combustion engine according to claim 5 , wherein the melting time determination means determines the melting time based on at least one of an outside air temperature, an intake air temperature, a water temperature, and an oil temperature.

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