JP3586975B2 - Idle speed control device for internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an idle speed control device for an internal combustion engine, and more particularly to an idle speed control device for an internal combustion engine suitable for stably controlling the speed at the start of the internal combustion engine.
[0002]
[Prior art]
In an internal combustion engine, it is desirable to increase the length of the intake pipe in order to improve the torque characteristics in the low-speed rotation region. In order to improve the performance of the internal combustion engine, it is advantageous that the diameter of the intake pipe is larger. is there. Further, when a supercharging device is provided, it is necessary to increase the length of the intake pipe. Thus, as the performance of the internal combustion engine is improved, the capacity of the intake system tends to increase. Before starting the internal combustion engine, the intake system is filled with air at atmospheric pressure. Therefore, when the volume of the intake system is large, a large amount of air is sucked into the internal combustion engine even when the internal combustion engine is started with the throttle valve fully closed. In this state, when the idle speed control valve (hereinafter, referred to as ISCV) is opened, the intake air amount of the internal combustion engine further increases. In this case, the rotational speed at the time of starting the engine may exceed the required rotational speed and may be blown up, causing the driver to feel uncomfortable, for example, causing vibration of the vehicle.
[0003]
In order to suppress such an increase in the number of revolutions when the internal combustion engine is started, for example, the ISCV is fully closed when the internal combustion engine is started, as in an idle speed control device for an internal combustion engine disclosed in Japanese Utility Model Application Laid-Open No. 58-153332. Is effective.
[0004]
[Problems to be solved by the invention]
However, the above-described conventional device is to fully close the ISCV for the purpose of reducing the load on the battery. When the ISCV is fully closed at the time of starting the internal combustion engine, the result is that the ISCV is eventually closed. Only an increase in the rotational speed is suppressed. Therefore, in the above-described conventional apparatus, no consideration is given to controlling the rotational speed optimally based on the operating state of the internal combustion engine. For this reason, the above-described conventional apparatus is effective in preventing the rotational speed from rising when the internal combustion engine is started, but the engine rotational speed is unstable, such as a decrease in the rotational speed because the rotational speed is not properly controlled. There was a problem that it might be.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in consideration of the above-described circumstances. It is an object to provide a rotation speed control device.
[0006]
[Means for Solving the Problems]
An object of the present invention is to provide an idle speed control device for an internal combustion engine, which controls an idle speed of the internal combustion engine by controlling an opening of an intake air amount control valve of the internal combustion engine, as described in claim 1.
Operating state detecting means for detecting an intake pressure of the internal combustion engine or an intake air amount per one rotation of the engine;
In the cranking state at the time of starting the internal combustion engine, the intake air amount control valve is detected by the operating state detecting means.The intake pressure or the intake air amountIs fully closed until a predetermined state set on the state side before the start of the internal combustion engine is reached from the target state corresponding to the target idle speed of the internal combustion engine,Intake pressure or intake air volumeStarting opening control means for opening the target opening when the predetermined state is reached;,With
In the cranking state at the time of starting the internal combustion engine, when the temperature of the internal combustion engine is lower than a predetermined value, the opening degree control unit at the time of starting prohibits a measure for completely closing the intake air amount control valve. YouThis is achieved by an idle speed control device for an internal combustion engine.
[0007]
In the present invention, the operating state detecting means detects an intake pressure or an intake air amount per one rotation of the engine as an operating state of the internal combustion engine. The starting opening degree control means, in the cranking state at the time of starting the internal combustion engine, sets the intake air amount control valve to a state in which the operation state detected by the operation state detection means corresponds to the target idle speed of the internal combustion engine. Also, the valve is fully closed until it reaches a predetermined state set on the state side before the start of the internal combustion engine, and opens to the target opening when the operating state reaches the predetermined state. Therefore, when the internal combustion engine is started, the idle speed of the internal combustion engine is controlled based on the operating state of the internal combustion engine.However, in the present invention, the measure for completely closing the intake air amount control valve in the cranking state at the time of starting the internal combustion engine is prohibited when the temperature of the internal combustion engine is lower than a predetermined value. Therefore, it is possible to avoid a situation in which the engine speed does not increase to the target idle speed due to the shortage of the intake air amount due to the low temperature of the internal combustion engine.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a system configuration diagram of an embodiment of the present invention. The present embodiment is an example in which the idle speed control device for an internal combustion engine according to the present invention is applied to an internal combustion engine 10. In FIG. 1, the internal combustion engine 10 includes a cylinder block 12. A water jacket 14 through which cooling water circulates is provided in the wall of the cylinder block 12. The cylinder block 12 is provided with a water temperature sensor 16 for detecting the temperature of the cooling water flowing through the water jacket 14.
[0009]
A piston 18 is housed inside the cylinder 12 in a liquid-tight and slidable manner. The internal combustion engine 10 of this embodiment is a multi-cylinder internal combustion engine, and a plurality of pistons (not shown) are housed in the cylinder block 12 in addition to the pistons 18. A combustion chamber 20 is formed inside the cylinder block 12 above the piston 18. The front end of the ignition plug 22 is exposed to the combustion chamber 20, and an intake manifold 28 and an exhaust manifold 30 communicate with each other via an intake valve 24 and an exhaust valve 26, respectively.
[0010]
The intake manifold 28 includes a plurality of branch pipes that communicate each cylinder of the internal combustion engine 10 with the surge tank 32. Each branch pipe is provided with an injector 34 of a solenoid valve type. In the internal combustion engine 10, the fuel injection amount can be changed by changing the time length of the drive signal supplied to the injector 34. The surge tank 32 is provided with an intake air temperature sensor 40 and an intake pressure sensor 42. The intake air temperature sensor 40 generates an output signal corresponding to the temperature of the air flowing through the surge tank 32. Further, the intake pressure sensor 42 generates an output signal corresponding to the pressure of the air in the surge tank 32, that is, the intake pressure of the internal combustion engine 10.
[0011]
An intake pipe 44 is connected to an upstream side of the surge tank 32. A throttle valve 46 is provided inside the intake pipe 44. The throttle valve 46 is configured to operate in conjunction with the accelerator pedal. A throttle position sensor 48 for detecting the opening of the throttle valve 46 is connected to the throttle valve 46.
[0012]
The intake pipe 44 and the surge tank 32 are connected by a bypass passage 50 that bypasses the throttle valve 46. Therefore, even if the throttle valve 46 is in the fully closed state, the air is supplied to the internal combustion engine 10 if the bypass passage 50 is in the conductive state. In the bypass passage 50, an idle speed control valve (hereinafter, referred to as ISCV) 52 is provided. The ISCV 52 is a solenoid-type solenoid valve, and its opening is controlled by the duty ratio of a drive signal supplied from the outside to the solenoid. When the throttle valve 46 is fully closed, an amount of air corresponding to the opening of the ISCV 52 is supplied to the internal combustion engine 10. Therefore, by controlling the opening of the ISCV 52, the idle speed of the internal combustion engine 10 can be controlled.
[0013]
An air filter 54 communicates with the intake pipe 44 on the upstream side of the throttle valve 46. Therefore, the clean air filtered by the air filter 54 flows into the intake pipe 44.
The internal combustion engine 10 is provided with an igniter 56 that includes an ignition coil and generates a high voltage necessary for ignition, a distributor 58 that distributes the high voltage generated by the igniter 56 to the ignition plug 22 of each cylinder, and a distributor 58. A rotation angle sensor 60 and a cylinder discrimination sensor 62 are provided. The engine speed NE is calculated based on the output signal of the rotation angle sensor 60. Further, the internal combustion engine 10 includes a starter 64. The starter 64 is an electric motor whose output shaft is connected to the output shaft of the internal combustion engine 10. Therefore, when the starter 64 is started, the output shaft of the internal combustion engine 10 is forcibly rotated to be in a cranking state, whereby the internal combustion engine 10 is started. The start of the internal combustion engine 10 by such a starter 64 is hereinafter referred to as cranking start.
[0014]
The above-described water temperature sensor 16, ignition plug 22, injector 34, intake air temperature sensor 40, intake pressure sensor 42, throttle sensor 46, ISCV 52, rotation angle sensor 60, and cylinder discrimination sensor 62 are electronic control units (hereinafter referred to as ECUs). 66. Further, a starter 64 is connected to the ECU 66 via a starter switch 68. The ECU 66 can determine whether the internal combustion engine 10 is in the cranking state by detecting whether the starter switch 68 is on or off. The ECU 66 provides a fuel injection amount, ignition timing, The intake air amount and the like during the idling operation are calculated, and the ignition plug 22, the injector 34, the ISCV 52, and the like are controlled.
[0015]
Before the ignition switch is turned on, that is, when the ECU 66 is not energized, the opening of the ISCV 52 (hereinafter referred to as ISC opening) is mechanically maintained at 50%. When the ignition switch is turned on and the ECU 66 is energized, the ECU 66 starts executing an initialization routine, and issues a fully-close command to the ISCV 52 in this routine. Therefore, after the ignition switch is turned on, the ISCV 52 is fully closed. Further, as will be described later, at the same time when the starter switch 68 is turned on, the execution of a time measurement routine for measuring the elapsed time thereafter is started, and when the internal combustion engine 10 starts rotating by starting the starter 64, a predetermined An ISC opening control routine is executed for each crank angle.
[0016]
By the way, when the internal combustion engine 10 is stopped, the intake system such as the intake manifold 28, the surge tank 32, and the intake pipe 44 is filled with air at atmospheric pressure. Therefore, even when the throttle valve 44 and the ISCV 52 are fully closed, air existing in the intake system is sucked into the internal combustion engine 10. In particular, at the time of startup, a large amount of air is drawn into the internal combustion engine 10 per rotation because the rotation speed NE of the internal combustion engine 10 is low. In such a state, when the ISC opening is opened to achieve a predetermined idle speed, the intake air amount of the internal combustion engine 10 further increases, the engine speed at startup increases, and vibrations occur in the vehicle. As a result, inconvenience such as giving a sense of incongruity to the driver occurs.
[0017]
On the other hand, the system according to the present embodiment starts the starter 64, that is, completely closes the ISCV 52 at the same time as entering the cranking state, and then opens the ISCV 52 at an appropriate timing. It is characterized in that the number of revolutions can be stably increased to a target number of revolutions without causing a blow-up.
[0018]
As described above, the ECU 66 starts executing the time measurement routine at the same time when the starter switch 68 is turned on, and measures the elapsed time CSTATON after the starter 64 is activated. As will be described later, in the ISC opening control routine, the start failure of the internal combustion engine 10 is detected using the elapsed time CSTATON. Therefore, first, the contents of the time measurement routine executed by the ECU 66 will be described with reference to FIG.
[0019]
FIG. 2 shows a flowchart of the time measurement routine. This routine is repeatedly started at predetermined time intervals DT after the ignition switch is turned on. When this routine is started, first, in step 102, the variable CSTAON is increased by DT. The variable CSTAON is initialized to zero when this routine is first executed after the ignition switch is turned on. Therefore, by the processing in step 102, the elapsed time after the ignition switch is turned on is set in CSTAON. When the process of step 102 is completed, the process of step 104 is executed.
[0020]
In step 104, the value of the variable STL is set based on the on / off state of the starter switch 68. That is, when the starter switch 68 is on, the STL is set to a high level (H), and when the starter switch 68 is off, the STL is set to a low level (L). When the process of step 104 is completed, next, a process of step 106 is executed.
[0021]
In step 106, it is determined whether or not the STL value STL0 at the time of the previous execution of this routine is L and the current STL is H. If an affirmative determination is made in step 106, it is determined that the starter 64 has been started, and then, in step 108, zero is substituted for CSTAON. Therefore, hereinafter, CSTAON indicates the elapsed time since the starter 64 was activated. When the process of step 108 is completed, the process of step 110 is executed.
[0022]
On the other hand, if a negative determination is made in step 106, step 108 is skipped, and the process of step 110 is performed next. In step 110, the value of STL is substituted for STL0. Thus, in the next execution of this routine, STL0 can be used as the value of the previous STL. When the process of step 110 is completed, the current routine ends.
[0023]
Next, the contents of the ISC opening control routine executed by the ECU 66 in the present embodiment will be described with reference to FIG. FIG. 3 shows a flowchart of the ISC opening control routine. This routine is executed every time the rotation angle of the internal combustion engine 10 reaches a predetermined crank angle after the starter 64 is started.
[0024]
This ISC opening degree control routine controls the engine speed NE at the time of starting the internal combustion engine 10 toward the target speed NEc. As described above, immediately after the start of the cranking start of the internal combustion engine 10, the ISCV 52 and the throttle valve 44 are fully closed. Even when the throttle valve 44 is fully closed, there is a gap between the throttle valve 44 and the inner wall of the intake pipe 42. Therefore, air flows through the gap, and a fixed amount of air is sucked into the internal combustion engine 10. That is, at the time of cranking start of the internal combustion engine 10, the intake air amount qa per unit time of the internal combustion engine 10 is constant, and therefore, the intake air amount qn per rotation of the internal combustion engine 10 is inversely proportional to the rotation speed NE. Change. In general, the intake air amount qn per rotation of the internal combustion engine 10 changes almost in proportion to the intake pressure PM. Therefore, the intake pressure PM changes almost in inverse proportion to the rotational speed NE. Therefore, in the present embodiment, the target intake pressure PMc corresponding to the target engine speed NEc during the idling operation of the internal combustion engine 10 is determined, and the intake pressure PM is controlled by using the target intake pressure PMc as a target value. The number NE is controlled toward the target rotational speed NEc.
[0025]
When the routine shown in FIG. 3 is started, first, in step 120, the target opening DOP of the ISCV 52 for realizing the target rotational speed NEc is calculated on the assumption that the engine is in a steady idling operation state. The target opening degree DOP is calculated based on the state of the vehicle, for example, the temperature of the intake air of the internal combustion engine 10, the operating state of the air conditioner, and the like. When the process of step 120 is completed, next, a process of step 122 is executed.
[0026]
In step 122, it is determined whether the coolant temperature THW of the internal combustion engine 10 detected by the coolant temperature sensor 16 is equal to or higher than a predetermined temperature TH0. If it is determined in step 122 that THW ≧ TH0 is not established, then, in step 124, a process for setting the ISC opening to DOP is executed. Such processing is performed by the ECU 66 issuing a drive signal having a duty ratio corresponding to the DOP to the ISCV 52.
[0027]
As described above, in this routine, the process of fully closing the ISC opening is performed in order to suppress an increase in the idle speed at the time of starting the internal combustion engine 10. However, when the internal combustion engine 10 is in a very low temperature state, the viscosity of the lubricating oil increases, and a large frictional force acts on the piston 14. If the process of completely closing the ISC opening is performed in such a state, there is a possibility that a situation may occur in which the intake air amount becomes insufficient and the rotation speed of the internal combustion engine 10 cannot be increased to the target rotation speed NEc. Therefore, in the present embodiment, it is determined whether or not the temperature of the internal combustion engine 10 is low enough to cause such a situation based on the temperature THW of the cooling water, and the ISC opening is set according to the determination result. I'm supposed to. That is, the upper limit value TH0 of THW at which the measure to completely close the ISC opening should be prohibited is obtained in advance, and if it is determined in step 122 that the THW is smaller than the predetermined value TH0, the process proceeds to step 124 immediately. By executing the processing, the ISC opening is set to the target opening DOP. In this embodiment, the value of TH0 is, for example, -1.5 ° C.
[0028]
On the other hand, if it is determined in step 122 that THW ≧ TH0 holds, then in step 126, it is determined whether or not CSTAON is less than a predetermined value T0. In step 126, CSTAON <T0UnsuccessfulIs determined, the process of step 124 is executed.
[0029]
Since the internal combustion engine 10 is started by the starter 64, if the internal combustion engine 10 is started normally, the rotation speed of the internal combustion engine 10 becomes constant after a certain period of time has elapsed since the starter 64 was started. Rise above. However, if the fuel injection control failure, the ignition failure of the spark plug 22, the fuel property failure, or the like occurs, the internal combustion engine 10 is not started normally, and the rotational speed NE cannot increase as normal. In such a case, if the ISC opening is maintained in the fully closed state, the start of the internal combustion engine 10 is further hindered. On the other hand, when the internal combustion engine 10 is started normally, it is necessary to set the ISC opening to the target opening DOP at the time when the starting is completed after a certain period of time.
[0030]
Therefore, in the present embodiment, when the elapsed time CSTAON after the starter 64 is started becomes equal to or longer than the predetermined time T0 in step 122, the process of step 124 is immediately executed to open the ISCV 52. And set the target opening DOP. The predetermined time T0 is set so as to slightly exceed the maximum value of the elapsed time from the start of the starter 64 to the start of the internal combustion engine 10 in a normal state, and is set to, for example, 1.5 seconds in the present embodiment.
[0031]
On the other hand, if it is determined in step 126 that CSTAON <T0 holds, it is determined that the internal combustion engine 10 is still being started, and the processing of step 128 and thereafter is executed. In step 128, it is determined whether the flag FL is set. The flag FL is a flag indicating whether or not the process of completely closing the ISC opening has been executed at the time of the previous execution of this routine, and has been initialized to a reset state. If it is determined in step 128 that the FL has not been set, it is determined that the process of completely closing the ISC opening has not been performed last time, and then the process of step 130 is performed. On the other hand, if it is determined in step 128 that FL has been set, it is determined that the process of completely closing the ISC opening has been executed last time, and then the process of step 132 is executed.
[0032]
In step 130, it is determined whether the intake pressure PM of the internal combustion engine 10 detected by the intake pressure sensor 42 is higher than a predetermined pressure PM0. If it is determined in step 130 that PM> PM0 is satisfied, then in step 134, the flag FL is set. When the process of step 134 is completed, next, in step 136, the target opening DOP is set to zero, and then the process of step 124 is executed. Therefore, when PM> PM0 holds, the ISCV 52 is fully closed. On the other hand, if it is determined in step 130 that PM> PM0 is not satisfied, steps 134 and 136 are skipped, and the process of step 124 is executed. Therefore, when PM ≦ PM0 holds, the ISCV 52 is opened to the target opening DOP calculated in step 120.
[0033]
On the other hand, in step 132, it is determined whether or not the intake pressure PM is higher than a predetermined pressure PM1. If it is determined in step 132 that PM> PM1 holds, then the processing of step 136 and the subsequent step 124 are executed. Therefore, if PM> PM1 holds, the ISCV 52 is fully closed. On the other hand, if it is determined in step 132 that PM> PM1 is not established, then, in step 138, after the flag FL is reset, the processing in step 124 is executed. Therefore, when PM ≦ PM1, the ISCV 52 is opened to the target opening DOP calculated in step 120. The above-mentioned predetermined pressures PM0 and PM1 are provided such that PM0> PM1. When the process of step 124 is completed, the current routine ends.
[0034]
As described above, before the internal combustion engine 10 is started, the intake system is filled with air at atmospheric pressure, and the PM is equal to the atmospheric pressure. Therefore, when this routine is executed for the first time after the cranking start is started, a negative determination is made in step 128 and a positive determination is made in step 130. Then, after the flag FL is set in step 134, the processing in steps 136 and 124 is executed, so that the ISC opening is fully closed. Therefore, in the next execution of this routine, the ISCV 52 is in the fully closed state and the flag FL is set. As described above, PM0 and PM1 are provided such that PM0> PM1. Therefore, in the second and subsequent executions of this routine, the ISCV 52 is kept in the fully closed state until the PM decreases to PM1, and when the PM reaches PM1, the ISC opening is calculated by the target calculated in step 120. The opening degree DOP is set.
[0035]
Meanwhile, a surge tank 32 and an intake manifold 28 are provided between the ISCV 52 and the intake valve 24 of the internal combustion engine 10, and a considerably large capacity exists between them. For this reason, even if the ISC opening is changed, it takes a certain amount of time for the amount of air corresponding to the changed ISC opening to be sucked into the internal combustion engine 10. That is, after the ISC opening is set, a delay occurs until the rotation speed of the internal combustion engine 10 reaches a value corresponding to the set value. Therefore, if the ISC opening is fully closed immediately after the start of the cranking start and the ISCV 52 is opened when the intake pressure PM reaches the pressure PMc corresponding to the target rotational speed NEc, the ISCV 52 may not be opened. The timing of the valve is too late, the intake air amount becomes insufficient, and the rotational speed NE again falls below NEc.
[0036]
Therefore, in the present embodiment, PM1 is set so that the ISCV 52 is opened earlier in consideration of the delay after the setting of the ISC opening as described above, and when the intake pressure PM reaches PM1, the ISCV 52 is reset. The valve is to be opened to the target opening degree DOP. This prevents the engine speed NE from decreasing again after reaching the target engine speed NEc, thereby suppressing fluctuations in the engine speed NE at the time of engine start. In this embodiment, PM0 and PM1 are set to, for example, 80 kPa and 40 kPa, respectively.
[0037]
If it is determined in step 132 that the determination is made as PM ≦ PM1, the flag FL is reset in step 138. Therefore, at the time of the next execution, after a negative determination is made in step 128, the ISC opening is set in steps 130 to 124 based on the comparison between PM and PM0. As described above, PM0 and PM1 are provided such that PM0> PM1. Therefore, immediately after PM ≦ PM1 is satisfied and the ISC opening is set to DOP, even when PM> PM1 again, the ISC opening is set to DOP unless PM exceeds PM0. State is maintained. As described above, in this embodiment, by changing the reference value of PM when setting the ISC opening to PM0 or PM1 in accordance with the content of the flag FL, the PM fluctuates in a vibrating manner around PM1. In this case, it is possible to prevent the fully closing process and the valve opening process of the ISCV 52 from being repeatedly performed.
[0038]
Next, FIG. 4 is a solid line showing a time chart of the ISC opening and the rotational speed NE of the internal combustion engine 10 when the internal combustion engine 10 is started when the ECU 66 executes the above routine. FIG. 4 shows that the ISCV 52 is fully closed immediately after the start of the cranking start, that is, when the ISCV 52 is opened to the target opening DOP simultaneously with the start of the starter 64, and immediately after the starter 64 is started. After that, when the PM reaches PMc, the ISCV 52 is opened to the DOP,oneThis is indicated by a dotted chain line.
[0039]
As shown by the broken line in FIG. 4, when the ISCV 52 is opened simultaneously with the start of the starter 64, the engine speed NE overshoots the target engine speed NEc. As described above, such an overshoot causes a large amount of intake air of the internal combustion engine 10 by opening the ISCV 52 in a state where air at atmospheric pressure is present in the intake system immediately after the start of the internal combustion engine 10. It is caused by the above. When the ISC opening is fully closed immediately after the start of cranking and the ISC opening is set to DOP when the intake pressure PM reaches PMc, as indicated by the dashed line in FIG. NE undershoots after reaching NEc. As described above, such an undershoot is caused by a delay time from when the ISCV 52 is opened to when the intake air amount of the internal combustion engine 10 increases due to the opening.
[0040]
In contrast, in the present embodiment, the ISCV 52 is fully closed immediately after the start of cranking, and when the intake pressure PM reaches PM1 set in consideration of the delay time as described above, the ISCV 52 By opening the valve, the rotational speed NE of the internal combustion engine 10 is quickly increased to the target idle rotational speed NEc without causing overshoot or undershoot, as shown by the solid line in FIG.
[0041]
As described above, according to the idle speed control device for the internal combustion engine of the present embodiment, the speed of the internal combustion engine 10 at the time of starting can be stabilized to the target speed without fluctuations such as overshoot and undershoot. This can prevent the driver from feeling uncomfortable, such as vibration of the vehicle, when the internal combustion engine 10 is started.
[0042]
Next, a second embodiment of the present invention will be described with reference to FIGS. This embodiment is the same as the first embodiment except that the ECU 66 executes the routine shown in FIG. 7 instead of the routine shown in FIG. 3 in the system shown in FIG. This embodiment is characterized in that the ISC opening is continuously changed based on the intake pressure PM of the internal combustion engine 10 and the cooling water temperature THW of the internal combustion engine 10.
[0043]
As described above, immediately after the start of the internal combustion engine 10, the PM is substantially equal to the atmospheric pressure, and when the engine speed NE increases, the PM decreases substantially in inverse proportion to the NE. Therefore, in order to make the rotation speed immediately after the start of the internal combustion engine 10 reach the target rotation speed NEc without any overshoot or undershoot, the ISC opening is completely closed immediately after the start of the internal combustion engine 10, It is appropriate to gradually increase the ISC opening in accordance with the increase in NE, that is, the decrease in PM, and to set the ISC opening to the target opening DOP when the NE reaches the vicinity of NEc. Further, as described above, when the internal combustion engine 10 is in a low temperature state, the viscosity of the lubricating oil increases, and the frictional force on the piston 18 increases. In this case, it is appropriate to increase the amount of intake air of the internal combustion engine 10 in order to increase the power generated by the internal combustion engine 10 so that the frictional force is compensated.
[0044]
Therefore, in the present embodiment, the upper limit value DST is set based on the intake pressure PM and the cooling water temperature THW, respectively.G, And the upper limit value DSTW are determined, and guard processing is performed on the DOP based on the sum of the upper limit values, thereby realizing the ISC opening according to the PM and the THW as described above.
[0045]
Fig. 5 shows PM and DST.GShows the relationship with As shown in FIG. 5, the DSTG is 0% (fully closed) in a region where PM exceeds a predetermined value PM3, increases in a region from PM3 to PM4 in accordance with the decrease in PM, and 100% in a region below PM4. (Fully open)WhenIt is provided so that it becomes. The relationship as shown in FIG. 5 can be obtained by experimentally obtaining a change in the ISC opening degree with respect to PM so as to optimize the rotation speed at the time of starting the internal combustion engine 10.
[0046]
FIG. 6 shows the relationship between THW and DSTW. As shown in FIG. 6, the DSTW is provided so that when the THW is equal to or lower than a predetermined temperature, the DSTW increases as the THW decreases. Note that the relationship as shown in FIG. 6 can be obtained by experimentally obtaining the ISC opening required for realizing the target rotational speed NEc at various cooling water temperatures THW.
[0047]
Next, the contents of the ISC opening control routine executed by the ECU 66 in this embodiment will be described with reference to FIG. FIG. 7 shows a flowchart of an ISC opening degree control routine executed by the ECU 66 in the present embodiment. In FIG. 7, the same steps as those in the routine shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.
[0048]
In the routine shown in FIG. 7, if it is determined in step 126 that the elapsed time CSTAON since the starter 64 was turned on has not reached T0, then the process of step 150 is executed. In step 150, a guard process is performed for the target opening degree DOP of the ISCV 52 with the upper limit value being the sum of the upper limit value DSTG based on the intake pressure PM and the upper limit value DSWT based on the coolant temperature THW. That is, in step 150, DOP is compared with (DSTG + DSW), and if DOP ≦ (DSTG + DSW), the value of DOP is not changed, and if DOP> (DSTG + DSW), (DSTG + DSW) is substituted into DOP. Processing is executed.
[0049]
In the present embodiment, the relationship as shown in FIGS. 6 and 7 is stored in the ECU 66 in advance. Then, when step 150 is executed, the DSTG and the DSW are determined from the PM and the THW based on the stored values. When the processing in step 150 is completed, the ISC opening is set in step 124, and the current routine is terminated.
[0050]
As described above, according to the present embodiment, the ISC opening at the start of the internal combustion engine 10 is continuously set based on the intake pressure PM and the cooling water temperature THW, so that the ISC opening is set in a more optimal state. Can be set to Therefore, according to the present embodiment, the rotational speed NE at the time of starting the internal combustion engine 10 can be more stably and promptly increased to the target rotational speed NEc as compared with the case of the first embodiment.
[0051]
In the first and second embodiments, the water temperature sensor 16 and the intake pressure sensor 42 correspond to the above-mentioned operating condition detecting means. Therefore, the cooling water temperature THW and the intake pressure PM correspond to the above operating condition of the internal combustion engine. Is equivalent to The ISCV 52 corresponds to the above-described intake air amount control valve, and the ECU 66 executes the ISC opening degree control routine shown in FIG. 3 or FIG.
[0052]
However, the operating state of the internal combustion engine is not limited to the cooling water temperature THW and the intake pressure PM, and the present invention is applied to an internal combustion engine of a type having an air flow meter instead of the intake pressure sensor 42, and The amount of intake air per rotation can be used as the operating state of the internal combustion engine. In addition, as the operating state of the internal combustion engine, the engine speed NE, the vibration state of the internal combustion engine detected by the acceleration sensor, the intake air temperature detected by the intake air temperature sensor 40, and the like can be used.
[0053]
【The invention's effect】
As described above, according to the present invention, it is possible to stably control the rotation speed at the time of starting the internal combustion engine. This can prevent the driver from feeling uncomfortable when the internal combustion engine is started.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an embodiment of the present invention.
FIG. 2 is a flowchart of a time measurement routine executed by an ECU in the embodiment.
FIG. 3 is a flowchart of an ISC opening control routine executed by an ECU in the embodiment.
FIG. 4 is a time chart showing an execution result of the embodiment.
FIG. 5 is a diagram showing a relationship between intake pressure PM and upper limit value DSTG.
FIG. 6 is a diagram showing a relationship between a cooling water temperature THW and an upper limit value DSGW.
FIG. 7 is a flowchart of an ISC opening control routine executed by an ECU according to a second embodiment of the present invention.
[Explanation of symbols]
10 Internal combustion engine
16 Water temperature sensor
42 Intake pressure sensor
52 ISCV
64 Starter
66 ECU

Claims (1)

An idle speed control device for an internal combustion engine that controls an idle speed of the internal combustion engine by controlling an opening degree of an intake air amount control valve of the internal combustion engine,
Operating state detecting means for detecting an intake pressure of the internal combustion engine or an intake air amount per one rotation of the engine;
In a cranking state at the time of starting the internal combustion engine, the intake air amount control valve is set to a target in which the intake pressure or the intake air amount detected by the operating state detection means corresponds to a target idle speed of the internal combustion engine. The valve is fully closed until a predetermined state set before the start of the internal combustion engine is reached from the state, and the valve is opened to a target opening when the intake pressure or the intake air amount reaches the predetermined state. a starting time opening control means comprises,
In the cranking state at the time of starting the internal combustion engine, when the temperature of the internal combustion engine is lower than a predetermined value, the opening degree control unit at the time of starting prohibits a measure for completely closing the intake air amount control valve. idle speed control apparatus for an internal combustion engine, wherein to Rukoto.

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