JP2009293400A - Throttle valve control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throttle valve control device capable of improving responsiveness to a driver's acceleration demand while surely preventing the deterioration of a combustion state immediately after the start of an internal combustion engine using alcohol as fuel. <P>SOLUTION: An upper limit variation DTHTWN and a lower limit variation DTHTWNBS are computed according to parameters TW, TWINI showing an engine temperature and an alcohol concentration parameter KREFBS (S18, S19). A regulation variation DTHTWG is set to the lower limit variation DTHTWNBS immediately after the engine start and controlled to gradually increase toward the upper limit variation DTHTWN with the lapse of time. The increase speed of a throttle valve opening is regulated by the regulation variation DTHTWG. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a throttle valve control device for an internal combustion engine that uses alcohol as fuel, and more particularly to a device that restricts the rapid opening of the throttle valve immediately after the engine is cold-started.

  Patent Document 1 discloses a throttle control device that sets a valve opening speed of a throttle valve according to a warm-up state of an engine. According to this device, when the engine cooling water temperature is lower than the predetermined temperature, the valve opening speed is regulated to be equal to or lower than the upper limit speed corresponding to the engine cooling water temperature. As a result, the throttle valve is suddenly opened immediately after the cold start of the engine, and the air-fuel mixture supplied to the engine is prevented from being diluted.

  Patent Document 2 discloses a method for controlling the opening speed of a throttle valve in accordance with the alcohol concentration in a fuel containing alcohol. According to this method, when the throttle valve opening speed is obtained from the accelerator pedal depression speed, the throttle valve opening speed is controlled to decrease as the alcohol concentration increases.

Japanese Utility Model Publication No. 3-13541 Japanese Patent No. 3044719

  The combustion chamber temperature that has the greatest influence on the combustion state of the engine becomes higher as the elapsed time after the engine starts (after the start of the self-sustaining operation) becomes longer, but this is not taken into consideration in the apparatus disclosed in Patent Document 1. That is, even if the temperature in the combustion chamber rises, there is a delay until the engine cooling water temperature rises, and while the engine cooling water temperature is low, the increase speed of the throttle valve opening is regulated more than necessary, and the operability deteriorates. May invite.

  The method disclosed in Patent Document 2 is intended to make the acceleration corresponding to the accelerator pedal operation constant regardless of the alcohol concentration, and prevents deterioration of the combustion state immediately after the engine is started. It does not provide a method.

  The present invention has been made paying attention to the above-mentioned points, and improves the responsiveness to the driver's acceleration request while reliably preventing the deterioration of the combustion state immediately after the start of the internal combustion engine using alcohol as fuel. It is an object of the present invention to provide a throttle valve control device that can be used.

  In order to achieve the above object, the invention according to claim 1 is a throttle valve control device for an internal combustion engine that controls the opening (TH) of the throttle valve of the internal combustion engine to coincide with the target opening (THO). Restriction value setting means for setting a restriction value (DTHTWG) of the change amount of the throttle valve opening according to at least a temperature parameter (TW) indicating the temperature of the engine, and the target within the range of the restriction value (DTHTWG) Target opening setting means for setting the opening (THOMXTWD, THO), the engine uses alcohol as fuel, and the regulation value setting means includes the temperature parameter (TW) and alcohol in the fuel. Upper and lower limit value setting means for setting an upper limit value (DTHTWNBS) and a lower limit value (DTHTWNBS) of the regulation value in accordance with the concentration (KREFBS); Transition control means for setting the regulation value (DTHTWWG) so as to gradually transition from the lower limit value (DTHTWNBS) to the upper limit value (DTHTWN) according to the elapsed time (CTACR) after engine startup. Features.

  According to a second aspect of the present invention, in the throttle valve control device for an internal combustion engine according to the first aspect, the transition control means includes an initial temperature parameter (TWINI) indicating a temperature of the engine at the start of the engine, and The transition control is performed according to the number of ignitions (CTACR) after starting the engine.

  According to a third aspect of the present invention, in the throttle valve control device for an internal combustion engine according to the first or second aspect, the target opening (THOMXTWD, THO) set by the target opening setting means is an idle speed of the engine. A correction means for changing the target opening (THOMXTWD, THO) to the predetermined throttle valve opening (THICMD) when it is smaller than the predetermined throttle valve opening (THICMD) necessary for maintaining the state; Features.

  According to the first aspect of the present invention, the upper limit value and the lower limit value of the throttle valve opening change amount are set according to the temperature parameter indicating the engine temperature and the alcohol concentration in the fuel. The regulation value is set so as to gradually shift from the lower limit value to the upper limit value according to time. Therefore, immediately after starting, the regulation value is set near the lower limit value, and misfire can be reliably prevented. In addition, since the regulation value gradually increases toward the upper limit value in response to the increase in the combustion chamber temperature with the passage of time after starting, it is possible to improve the responsiveness to the driver's acceleration request. Furthermore, since the lower and upper limit values are set according to the alcohol concentration in the fuel, both the prevention of misfire and the improvement of operability can be achieved when using a fuel that has a high alcohol concentration and easily misfires. If the alcohol concentration is relatively low and the risk of misfire is small, it is possible to avoid excessive regulation.

  According to the second aspect of the present invention, the transition control from the lower limit value to the upper limit value is performed according to the initial temperature parameter indicating the engine temperature at the start of the engine start and the number of ignitions after the engine start. Since the engine temperature and the number of ignitions at the start of the start have a strong correlation with the temperature in the combustion chamber, by performing the transition control according to the initial temperature parameter and the number of ignitions, it becomes possible to control according to the transition of the combustion chamber temperature, Unnecessary restrictions can be avoided.

  According to the third aspect of the present invention, when the target opening is smaller than the predetermined throttle valve opening required to maintain the engine idle state, the throttle opening is changed to the predetermined throttle valve opening. Thus, it is possible to avoid the combustion state from becoming unstable.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention. An internal combustion engine (hereinafter referred to as “engine”) 1 is a four-cylinder engine that can be operated using alcohol, gasoline, and a mixture thereof as fuel. A throttle valve 3 is provided in the intake pipe 2 of the engine 1. An actuator 4 that drives the throttle valve 3 is connected to the throttle valve 3, and the actuator 4 is connected to an electronic control unit (hereinafter referred to as “ECU”) 5. The ECU 5 controls the opening degree TH of the throttle valve 3 via the actuator 4. A throttle valve opening sensor 22 for detecting the throttle valve opening TH is connected to the throttle valve 3, and a detection signal is supplied to the ECU 5.

  The fuel injection valve 6 is provided for each cylinder in the middle of the intake pipe 2 and slightly upstream of an intake valve (not shown) between the engine 1 and the throttle valve 3. The fuel injection valve 6 is connected to a fuel tank 9 through a fuel passage 8.

  The fuel injection valve 6 is electrically connected to the ECU 5, and a valve opening time and a valve opening timing are controlled by a signal from the ECU 5. An intake pressure sensor 23 for detecting the intake pressure PBA and an intake air temperature sensor 24 for detecting the intake air temperature TA are mounted on the downstream side of the throttle valve 3 of the intake pipe 2. Detection signals from these sensors are supplied to the ECU 5.

  The engine 1 is provided with a crank angle position sensor 25 that detects a rotation angle of a crankshaft (not shown) of the engine 1, and a signal corresponding to the rotation angle of the crankshaft is supplied to the ECU 5. The crank angle position sensor 25 is a cylinder discrimination sensor that outputs a pulse (hereinafter referred to as “CYL pulse”) at a predetermined crank angle position of a specific cylinder of the engine 1, and relates to a top dead center (TDC) at the start of the intake stroke of each cylinder. A TDC sensor that outputs a TDC pulse at a crank angle position before a predetermined crank angle (every 180 degrees of crank angle in a four-cylinder engine) and one pulse (hereinafter referred to as “CRK”) with a constant crank angle cycle shorter than the TDC pulse (for example, a cycle of 6 °). The CYL pulse, the TDC pulse, and the CRK pulse are supplied to the ECU 5. These pulses are used for various timing controls such as fuel injection timing and ignition timing, and detection of engine speed (engine speed) NE.

  An engine cooling water temperature sensor 26 for detecting the engine cooling water temperature TW is mounted on the main body of the engine 1, and the detection signal is supplied to the ECU 5. The exhaust pipe 12 of the engine 1 is provided with an oxygen concentration sensor (hereinafter referred to as “LAF sensor”) 27 for detecting the oxygen concentration in the exhaust, and the detection signal of the LAF sensor 27 is supplied to the ECU 5.

  Connected to the ECU 5 are an accelerator sensor 28 for detecting an accelerator pedal depression amount (hereinafter referred to as “accelerator pedal operation amount”) AP of a vehicle driven by the engine 1 and an atmospheric pressure sensor 29 for detecting an atmospheric pressure PA. The detection signals from these sensors are supplied to the ECU 5.

  The ECU 5 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, etc., and a central processing unit (hereinafter referred to as “CPU”). A storage circuit for storing various calculation programs executed by the CPU, calculation results, and the like, a fuel injection valve 6, an actuator 4, and an output circuit for supplying a drive signal to an ignition plug (not shown) of each cylinder. Is done.

  The ECU 5 calculates the target opening degree THO of the throttle valve 3 in accordance with the engine operating state such as the accelerator pedal operation amount AP and the engine speed NE so that the detected throttle valve opening degree TH matches the target opening degree THO. Next, the actuator 4 is controlled.

  2 and 3 are flowcharts of processing for calculating an increase amount restriction maximum opening THOMXTWD, which is a parameter for restricting the increase speed of the throttle valve opening TH. This process is executed every predetermined time (for example, 10 milliseconds) by the CPU of the ECU 5. The increase amount restriction maximum opening THOMXTWD is a parameter for restricting the amount of increase (increase speed) per unit time of the throttle valve opening TH immediately after the start of the engine.

  In step S11, the required opening THSELTW is calculated by adding the idle opening THICMD to the command opening THOMI calculated in accordance with the accelerator pedal operation amount AP and the engine speed NE. The idle opening THICMD is the minimum throttle valve opening necessary for maintaining the engine 1 in an idle state.

  In step S12, it is determined whether or not the required opening degree THSELTW is larger than an upper limit value THOMAXT (previous value) that is a minimum value of the maximum opening degree calculated by other processing (not shown). When the answer to step S12 is affirmative (YES), the post-limit processing required opening THSELTWD is set to the upper limit value THOMAXT (step S13), while when the answer to step S12 is negative (NO), the limit processing is performed. The rear required opening degree THSELTWD is set to the required opening degree THSELTW (step S14).

  In step S15, it is determined whether or not the DBW failure flag FFSPETDEF is “1”. The DBW failure flag FFSPETDEF is set to “1” when a failure of the drive device (for example, the actuator 22) of the throttle valve 3 is detected. If the answer to step S15 is affirmative (YES), the process proceeds to step S37 (FIG. 3), and the increase restriction maximum opening THOMXTWD is set to the maximum value THMAX0. The maximum value THMAX0 is set to the maximum value of the throttle valve opening TH, and by executing step S37, the restriction by the increase amount restriction maximum opening THOMXTWD is substantially not performed.

  If FFSPETDEF = 0 in step S15, it is determined whether or not the coolant temperature sensor failure flag FFSA06 is “1” (step S16). The coolant temperature sensor failure flag FFSA06 is set to “1” when a failure of the coolant temperature sensor 26 is detected. When FFSA06 = 1, both the cooling water temperature TW and the initial cooling water temperature TWINI are set to a predetermined water temperature THF (for example, −40 ° C.) (step S17), and the process proceeds to step S18. The initial coolant temperature TWINI is a coolant temperature detected and stored at the start of engine 1 start. If the answer to step S16 is negative (NO), the process immediately proceeds to step S18. In this case, the detected cooling water temperature TW and the stored initial cooling water temperature TWINI are applied to the calculations in steps S18 to S20 described below.

  In step S18, a DTHTWN map shown in FIG. 5A is retrieved according to the cooling water temperature TW and the alcohol concentration parameter KREFBS, and an upper limit change amount DTHTWN is calculated. The alcohol concentration parameter KREFBS is a parameter calculated by the process shown in FIG. 8 and indicating the alcohol concentration in the fuel being used. In this embodiment, the alcohol concentration parameter KREFBS is set to take “1.2” when the alcohol concentration is 100% and to take “0.7” when the alcohol concentration is 0% (gasoline 100%). .

  Lines L1, L2, and L3 in FIG. 5A are respectively a predetermined value KREFBS1 (for example, a value corresponding to about 22% alcohol concentration) and KREFBS2 (for example, a value corresponding to about 64% alcohol concentration) corresponding to a predetermined alcohol concentration. ), And KREFBS3 (for example, a value corresponding to an alcohol concentration of about 96%), and the relationship KREFBS1 <KREFBS2 <KREFBS3 is established. When the alcohol concentration parameter KREFBS takes a value other than the predetermined values KREFBS1, KREFBS2, and KREFBS3, the upper limit change amount DTHTWN is calculated by interpolation calculation or extrapolation calculation.

  The DTHTWN map shown in FIG. 5A is basically set so that the upper limit change amount DTHTWN increases as the coolant temperature TW increases, and the upper limit change amount DTHTWN decreases as the alcohol concentration parameter KREFBS increases. ing. The upper limit change amount DTHTWN corresponds to an increase rate of the throttle valve opening that can be allowed after a predetermined time (for example, 10 seconds) has elapsed from the time when the engine start is completed (the time when cranking is completed and the autonomous operation is started).

  In step S19, a DTHTWNBS map shown in FIG. 5B is searched according to the initial cooling water temperature TWINI and the alcohol concentration parameter KREFBS, and a lower limit change amount DTHTWNBS is calculated.

  Lines L11, L12, and L13 in FIG. 5B correspond to predetermined values KREFBS1, KREFBS2, and KREFBS3, respectively. When the alcohol concentration parameter KREFBS takes a value other than the predetermined values KREFBS1, KREFBS2, and KREFBS3, the lower limit change amount DTHTWNBS is calculated by interpolation or extrapolation.

  The DTHTWNBS map shown in FIG. 5B is basically set such that the lower limit change amount DTHTWNBS increases as the initial cooling water temperature TWINI increases, and the lower limit change amount DTHTWNBS decreases as the alcohol concentration parameter KREFBS increases. Has been. If the alcohol concentration parameter KREFBS is the same, the relationship DTHTWN> DTHTWNBS is established. The lower limit change amount DTHTWNBS corresponds to the increase rate of the throttle valve opening that can be allowed immediately after the engine is started.

  In step S20, a KTHOMXTWDACR map shown in FIG. 5C is retrieved according to the number of ignitions CTACR and the initial coolant temperature TWINI, and a transition coefficient KTHOMXTWDACR is calculated. The number of ignitions CTACR is the number of ignitions from when the engine 1 is started. 5C corresponds to the case where the initial cooling water temperature TWINI is “−10 ° C.”, the line L22 corresponds to the case where the initial cooling water temperature TWINI is “20 ° C.”, and the line L23 corresponds to the initial cooling. This corresponds to the case where the water temperature TWINI is “70 ° C.”. That is, the KTHOMXTWDACR map is set so that the transition coefficient KTHOMXTWDACR decreases as the initial coolant temperature TWINI increases, and the transition coefficient KTHOMXTWDACR decreases as the number of ignition times CTACR increases. CT1 to CT4 shown in FIG. 5C are set to, for example, “300”, “600”, “800”, and “1000”, respectively. When the initial cooling water temperature TWINI is a temperature other than “−10 ° C.”, “20 ° C.”, and “70 ° C.”, the transition coefficient KTHOMXTWDACR is calculated by interpolation calculation or extrapolation calculation.

In step S21, the upper limit change amount DTHTWN, the lower limit change amount DTHTWNBS, and the transition coefficient KTHOMXTWDACR are applied to the following equation (1) to calculate the basic change amount DTHTWNXF.
DTHTWNXF = DTHTWN
-KTHOMXTWDACR × (DTHTWN-DTHTWNBS)
(1)

  In step S22, a KTHTTWN table shown in FIG. 5 (d) is searched according to the engine speed NE, and a rotation speed correction coefficient KTHTTWN is calculated. The KTHTTWN table is set so that the rotational speed correction coefficient KTHTTWN decreases as the engine rotational speed NE decreases in the range of the predetermined rotational speed NE1 to NE2 (for example, a range of 1000 to 3000 rpm). This is because the lower the engine speed NE, the more easily the combustion state becomes worse due to the rapid opening of the throttle valve. By applying the rotational speed correction coefficient KNTHTWN, it is possible to prevent deterioration of the combustion state particularly in the operating state where the engine rotational speed NE is low.

In step S23, the regulation change amount DTHTWWG is calculated by multiplying the basic change amount DTHTWNXF by the rotation speed correction coefficient KNTHTWN.
In the subsequent step S31 of FIG. 3, the FTTWGCND setting process shown in FIG. 4 is executed to set the gradual increase control execution flag FTTWGCND.

  In step S51 of FIG. 4, a THTWGMIN map (not shown) is searched according to the engine speed NE and the coolant temperature TW, and the determination opening THTWGMIN is calculated. The THTWGMMIN map is basically set so that the determination opening THTWGMIN increases as the engine speed NE increases, and the determination opening THTWGMIN increases as the cooling water temperature TW increases. The determination opening THTWGMIN is set to a relatively low opening range (for example, about 3 to 15 degrees).

  In step S52, it is determined whether or not the requested opening degree THSELECTWD after the limit process is larger than the determination opening degree THTWGMIN. If the answer is affirmative (YES), it is determined that the throttle valve opening gradually increasing control should be executed, and the gradually increasing control execution flag FTHTWGCND is set to “1” (step S54). When the answer to step S52 is negative (NO), it is determined that it is not necessary to execute the gradual increase control of the throttle valve opening, and the gradual increase control execution flag FTTWGCND is set to “0” (step S53).

  Returning to FIG. 3, in step S <b> 32, it is determined whether or not the gradual increase control execution flag FTTWGCND is “1”. If this answer is negative (NO), the process proceeds to step S37, and the gradual increase control is not executed. When FTTWGCND = 0 and the answer to step S32 is negative (NO), the engine speed NE is in a relatively high speed range, or the engine coolant temperature TW is in a relatively high temperature range, In addition, when the required throttle valve opening is relatively low and the combustion state is maintained relatively stably, it is not necessary to regulate the increase amount of the throttle valve opening. Therefore, unnecessary restrictions can be avoided by steps S31 and S32. The determination opening THTWGMIN is preferably calculated based on both the engine speed NE and the cooling water temperature TW as described above, but may be calculated based on either the engine speed NE or the cooling water temperature TW. I do not care. In this case, the determination opening THTWMIN increases as the engine speed NE increases. Alternatively, the determination opening THTWMIN increases as the cooling water temperature TW increases.

  If the gradual increase control execution flag FTTWGCND is “1” in step S32, it is determined whether or not the target opening THO (previous value) is equal to or greater than the determination opening THTWGMMIN (step S33). When this answer is negative (NO), the provisional value THTWGTMP is set to the determination opening THTWGMMIN (step S34), and the process proceeds to step S38.

When THO ≧ THTWGMIN in step S33, the target opening degree THO (previous value) and the regulation change amount DTHTWG are applied to the following equation (2) to calculate the provisional value THTWGTMP (step S35).
THTWGTMP = THO + DTHTWG (2)

  In step S36, it is determined whether or not the calculated provisional value THTWGTMP is equal to or smaller than the post-limit processing required opening THSELTWD. If this answer is negative (NO), it is not necessary to execute the gradual increase control, and the process proceeds to step S37. On the other hand, if THTWGTMP ≦ THSELECTWD in step S36, the process proceeds to step S38.

  In step S38, it is determined whether or not the provisional value THTWGTMP is larger than the idle opening THICMD. When the answer is affirmative (YES), the increase amount restriction maximum opening THOMXTWD is set to the provisional value THTWGTMP (step S40). When THTHGTMP ≦ THICMD, the increase amount restriction maximum opening THOMXTWD is set to the idle opening THICMD (step S39).

FIG. 6 is a flowchart of processing for calculating the target opening THO. This process is executed by the CPU of the ECU 5 after the processes shown in FIGS.
In step S61, the command opening THOMI is calculated according to the accelerator pedal operation amount AP and the engine speed NE. Basically, the command opening THOMI is set to increase as the accelerator pedal operation amount AP increases. In step S62, the target opening THO is calculated by adding the idle opening THICMD to the command opening THOMI.

  In step S63, the smaller one of the increase amount restriction maximum opening THOMXTWD calculated in the processing of FIGS. 2 and 3 and the upper limit value THOMAXT which is the minimum value of the maximum opening calculated in other processing is selected. To calculate the upper limit opening THOMAX.

  In step S64, it is determined whether or not the target opening THO is larger than the upper limit opening THOMAX. If the answer is affirmative (YES), the target opening THO is set to the upper limit opening THOMAX (step S65). If THO ≦ THOMAX, this process is immediately terminated.

  When the increase amount (increase speed) of the command opening THOMI is larger than the increase amount (increase speed) of the target opening by the restriction change amount DTHTWG, the restriction change amount DTHTWWG is added to the previous target opening. The calculated increase amount regulation maximum opening THOMXTWD is set as the target opening THO. Therefore, the increasing speed of the target opening degree THO is regulated according to the regulation change amount DTHTWG, and finally, the increasing speed of the throttle valve opening degree TH is regulated.

  Next, a method for calculating the alcohol concentration parameter KREFBS will be described with reference to FIGS. The calculation of the alcohol concentration parameter KREFBS is executed when the fuel vapor is not purged and the fuel supply is not shut off. The calculated alcohol concentration parameter KREFBS is stored in a memory that retains the stored contents even when the engine is stopped, and the alcohol concentration parameter KREFBS read from the memory is used at the next engine start.

  In step S71, the air-fuel ratio A / F of the air-fuel mixture in the combustion chamber is calculated from the output of the LAF sensor 27. In step S72, the KAF table shown in FIG. 9 is searched according to the air-fuel ratio A / F, and the feedback coefficient KAF is calculated. The KAF table is set so that the feedback coefficient KAF increases as the air-fuel ratio A / F increases.

In step S73, the feedback coefficient KAF is applied to the following equation (3) to calculate the smoothed feedback coefficient KREFX. CREF in equation (3) is a smoothing coefficient set to a value between “0” and “1”, and KREFX on the right side is a previously calculated value.
KREFX = CREF × KAF + (1−CREF) × KREFX (3)

In step S74, the smoothing feedback coefficient KREFX is applied to the following equation (4) to update the alcohol concentration parameter KREFBS. KREFBS on the right side is the previous calculated value.
KREFBS = KREFBS × KREFX (4)

The calculated feedback coefficient KAF and alcohol concentration parameter KREFBS are applied to the following equation (5) to calculate the fuel injection amount TOUT. In the equation (5), TIM is a basic fuel amount calculated according to the engine speed NE and the intake pressure PBA, and K1 is another correction coefficient set according to the engine operating state.
TOUTM = TIM × KAF × KREFBS × K1 (5)

  As the alcohol concentration of the fuel increases, the detected air-fuel ratio A / F increases and the feedback coefficient KAF increases, so the alcohol concentration parameter KREFBS increases. If the fuel is constant and the alcohol concentration does not change, the feedback coefficient KAF decreases as the alcohol concentration parameter KREFBS increases, and the smoothed feedback coefficient KREFX converges to “1.0”. As a result, the alcohol concentration parameter KREFBS also converges to a value corresponding to the alcohol concentration.

  As described above in detail, in the present embodiment, the upper limit change amount DTHTWN and the lower limit change amount DTHTWNBS are set according to the cooling water temperature TW and the alcohol concentration parameter KREFBS indicating the alcohol concentration of the fuel being used, and the elapsed time after engine start-up Using a transition coefficient KTHOMXTWDACR set in accordance with the number of ignition times CTACR indicating time, as shown in FIG. 7 (time t0 indicates the start completion point), the lower limit change amount DTHTWNBS gradually shifts to the upper limit change amount DTHTWN. Thus, the regulation change amount DTHTWG is set. Therefore, immediately after the start, the regulation change amount DTHTWG is set in the vicinity of the lower limit change amount DTHTWNBS, so that misfire can be reliably prevented. Further, since the regulation change amount DTHTWG gradually increases toward the upper limit change amount DTHTWN in response to the increase in the combustion chamber temperature with the passage of time after starting, it is possible to improve the responsiveness to the driver's acceleration request. Furthermore, since the upper limit change amount DTHTWN and the lower limit change amount DTHTWNBS are set to values corresponding to the alcohol concentration in the fuel, when a fuel having a high alcohol concentration and easily misfires is used, misfire prevention and improved drivability are achieved. If the alcohol concentration is relatively low and the risk of misfire is small, it is possible to avoid excessive regulation.

  In addition, since the initial cooling water temperature TWINI and the ignition frequency CTACR have a strong correlation with the combustion chamber temperature, the transition of the combustion chamber temperature is determined by setting the transition coefficient KTHOMXTWDACR in consideration of not only the ignition frequency CTACR but also the initial cooling water temperature TWINI. It is possible to perform control according to the situation, and avoid unnecessary regulation.

  In addition, when the provisional value THTWGTMP is smaller than the idle opening THICMD which is the minimum throttle valve opening necessary for maintaining the idle state, the increase amount restriction maximum opening THOMXTWD is immediately changed to the idle opening THICMD. It is possible to avoid the combustion state becoming unstable in the idle state.

  In the present embodiment, when the increase amount restriction maximum opening THOMXTWD is smaller than the upper limit value THOMAXT determined from the maximum opening set by other processing, that is, the increase restriction maximum opening THOMXTWD is set to the target opening THO. Of course, it goes without saying that the above-described effects can be obtained.

  In the present embodiment, the ECU 5 constitutes a restriction value setting means, a target opening degree setting means, an upper / lower limit value setting means, a transition control means, and a correction means. Specifically, the processing in FIGS. 2 and 3 corresponds to the regulation value setting means, and the processing in FIG. 6 corresponds to the target opening setting means. 2 correspond to upper / lower limit setting means, steps S20 to S23 and steps S31 to S35 correspond to transition control means, and steps S38 and S39 correspond to correction means.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, an example in which an internal combustion engine using a fuel containing alcohol is controlled is shown. However, the present invention has two systems, a main fuel containing alcohol and a secondary fuel having a relatively high gasoline concentration. The present invention can also be applied to an internal combustion engine having a fuel supply means. In that case, the alcohol concentration of the main fuel is used as the alcohol concentration applied to the calculation of the upper limit change amount DTHTWN and the lower limit change amount DTHTWNBS.

  The DTHTWNBS map shown in FIG. 5B is set according to the initial cooling water temperature TWINI and the alcohol concentration parameter KREFBS. However, according to the cooling water temperature TW and the alcohol concentration parameter KREFBS, the DTHTWNBS map shown in FIG. You may make it set similarly to a map.

  In the above-described embodiment, the cooling water temperature TW is used as a parameter indicating the engine temperature. However, the lubricating oil temperature or the temperature at a predetermined location of the engine 1 may be used.

  The present invention can also be applied to throttle valve control of a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. It is a flowchart of the process which calculates the increase amount regulation maximum opening degree (THOMXTWD) which is a parameter which regulates the increase speed of a throttle valve opening degree. It is a flowchart of the process which calculates the increase amount regulation maximum opening degree (THOMXTWD) which is a parameter which regulates the increase speed of throttle valve opening degree. 4 is a flowchart of a flag setting subroutine executed in the process of FIG. It is a figure which shows the table or map referred by the process of FIGS. It is a flowchart of the process which calculates the target opening degree (THO) of a throttle valve. It is a time chart for demonstrating the control by the process of FIG.2 and FIG.3. It is a flowchart for demonstrating the calculation method of an alcohol concentration parameter (KREFBS). It is a figure which shows the table referred by the process of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 3 Throttle valve 4 Actuator 5 Electronic control unit (Regulation value setting means, target opening setting means, upper / lower limit value setting means, transition control means, correction means)
22 Throttle valve opening sensor 26 Engine coolant temperature sensor 27 Oxygen concentration sensor 28 Accelerator sensor

Claims (3)

In the throttle valve control device for an internal combustion engine that controls the opening of the throttle valve of the internal combustion engine to match the target opening,
Restriction value setting means for setting a restriction value of the amount of change in the throttle valve opening according to a temperature parameter indicating at least the temperature of the engine;
A target opening setting means for setting the target opening within the range of the regulation value,
The engine uses alcohol as fuel,
The restriction value setting means includes upper and lower limit value setting means for setting an upper limit value and a lower limit value of the restriction value according to the temperature parameter and an alcohol concentration in the fuel, and according to an elapsed time after the start of the engine. A throttle valve control device for an internal combustion engine, comprising: a transition control unit that sets the restriction value so as to gradually shift from the lower limit value to the upper limit value.   2. The transition control unit according to claim 1, wherein the transition control unit performs the transition control according to an initial temperature parameter indicating a temperature of the engine at a start of the engine and an ignition frequency after the engine is started. A throttle valve control device for an internal combustion engine.   When the target opening set by the target opening setting means is smaller than a predetermined throttle valve opening required to maintain the engine in an idle state, the target opening is changed to the predetermined throttle valve opening. The throttle valve control device for an internal combustion engine according to claim 1, further comprising correction means for performing the correction.

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