JP5273798B2 - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an air-fuel ratio from being made lean if an idle air volume control valve (IACV) is widely opened similarly to a normal starting period when a throttle valve is opened during idle stop control to start an engine. <P>SOLUTION: The target value ICMD of the opening of the IACV 24 is calculated including a water temperature correction coefficient. The water temperature correction coefficient is shifted between an engine starting period during the idle stop control and an engine starting period when a starter switch 33 is operated. In the engine starting during the idle stop control, the water temperature correction coefficient is reduced in comparison with the normal starting period to control the IACV 24 in a closing direction. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an engine control device, and more particularly to an engine control device that controls an idle air amount control valve provided in a bypass passage of a throttle valve.

  An idle air amount control valve (hereinafter referred to as “IACV”) is provided in a bypass passage that bypasses the throttle valve, and the amount of intake air during idle operation is adjusted by controlling the opening of the IACV when the throttle valve is fully closed. The engine to do is known. In Patent Document 1, an IACV feedback correction value, an air conditioner correction value, an air conditioner correction learning value, and the like are added to a basic output value obtained by performing a map search on the opening degree target value output to the IACV based on the cooling water temperature. An engine control device that calculates the value has been proposed.

  Further, as described in Patent Document 2, there is a vehicle that employs an idle stop control system that saves fuel and reduces exhaust gas by automatically stopping the engine at a temporary stop such as waiting for a signal. Are known. In the idle stop control, the engine is usually restarted when an occupant's intention to restart is detected by operating an accelerator operating device (accelerator grip, accelerator pedal, etc.) to open a throttle valve.

Japanese Patent No. 3755188 Japanese Patent No. 3824132

  Unlike the engine start by the starter switch, the engine start in the idle stop control always starts the engine by opening the throttle valve. Therefore, in the idling stop control, the intake air amount may increase when the engine is started and the air-fuel ratio tends to be lean.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an engine control device that can maintain an optimal air-fuel ratio at the time of engine start after an idle stop and prevent a lean tendency to improve vehicle start-up performance. .

  In order to achieve the above object, the present invention provides an engine control apparatus having an IACV that uses a water temperature correction coefficient according to the engine coolant temperature, and that the target opening value of the IACV increases as the water temperature correction coefficient increases. Opening target value calculation means for calculating the target opening value of the IACV using a calculation formula, and whether the engine start is an idle stop start during an idle stop control performed by opening a throttle valve or the like, or a normal start And a water temperature correction coefficient used in the opening target value calculation means is set to be smaller at the time of idling stop start than at the time of normal start. There are features.

  Further, the present invention provides a first correction coefficient table in which a normal start water temperature correction coefficient corresponding to the engine coolant temperature is set, and a second idle stop start water temperature correction coefficient corresponding to the engine coolant temperature. The second feature is that the correction coefficient table is provided.

  Further, the present invention provides a control means for performing air-fuel ratio control so that the richer the feedback coefficient is, the idle stop control is performed using a feedback coefficient calculated based on the oxygen concentration detected by the oxygen concentration sensor. Engine stop determining means for determining whether or not the engine is stopped in a state where the engine is maintained, and storage means for holding a feedback coefficient at that time when the engine is stopped while maintaining the idle stop control. A third feature is that the feedback coefficient held in the storage means is read by the control means when the engine is started during control.

  Further, the present invention has a fourth feature in that the engine stop in the idle stop control is performed by stopping the fuel supply to the engine, and the ignition is continued.

  According to the present invention having the first, second, and fourth features, the IACV opening target value calculation means including the water temperature correction coefficient is set to be smaller than the normal start time when the engine is started by opening the throttle valve. Since the water temperature correction coefficient is used, it is possible to improve the startability by suppressing the IACV opening target value to be small and suppressing the air-fuel ratio to become lean.

  According to the present invention having the third feature, when the engine is stopped by the idle stop control, the feedback coefficient at that time is retained, and when the engine is started by the idle stop control, the retained appropriate feedback coefficient is retained. Is read and used, an appropriate air-fuel ratio can be obtained in a short time after the engine is started.

  Thus, according to the present invention, in the engine having the idle stop control function, the air-fuel ratio of the air-fuel mixture supplied to the engine can be optimized.

It is a block diagram which shows the function of the engine control apparatus which concerns on one Embodiment of this invention. 1 is a side view of a motorcycle equipped with an engine control apparatus according to an embodiment of the present invention. It is a system configuration figure of an engine control device. It is a main flowchart concerning control of IACV. It is a flowchart which concerns on calculation of a water temperature correction coefficient. It is a figure which shows the water temperature-water temperature correction coefficient table which shows an example of a water temperature correction coefficient. It is a figure which shows the air | atmosphere-atmospheric pressure correction coefficient table which shows an example of an atmospheric pressure correction coefficient. It is a timing chart of O2 feedback control concerning a 2nd embodiment. It is a flowchart (the 1) of O2 feedback control. It is a flowchart (the 2) of O2 feedback control. It is a block diagram which shows the principal part function of O2 feedback control.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an overall side view of a scooter type motorcycle to which an engine control apparatus according to an embodiment of the present invention is applied.

  The vehicle body front portion and the vehicle body rear portion of the motorcycle 1 are connected to each other through a low floor portion 2, and a vehicle body frame forming a skeleton of the vehicle body extends from the head pipe 3 at the front of the vehicle body and the head pipe 3 downward and rearward. A down tube 4 and a main pipe 4. The main pipe 4 supports a fuel tank and a storage box (both not shown), and a seat 5 is disposed above the fuel tank and a storage box.

  A steering shaft 6 penetrates the head pipe 3 in the vertical direction and is rotatably supported. A steering handle 7 is attached above the steering shaft 6 and a front fork 8 is attached below. A front wheel FW is pivotally supported at the lower end of the front fork 8. The upper part of the steering handle 7 is covered with a handle cover 9 that also serves as an instrument panel. A bracket 10 projects from the lower end of the rising portion of the main pipe 4, and a hanger bracket 12 of a swing unit 11 is connected to the bracket 10 through a link member 13 so as to be swingable.

  The swing unit 11 is equipped with a single-cylinder four-cycle engine 14 at the front thereof. A belt-type continuously variable transmission 15 is connected to the engine 14 via a centrifugal clutch (not shown), and a speed reduction mechanism 16 is connected to the driven side of the belt-type continuously variable transmission 15. A rear wheel RW is supported on the output shaft of the speed reduction mechanism 16.

  A rear cushion 17 is interposed between the speed reduction mechanism 16 and the main pipe 4. An intake pipe 18 is drawn out from the front portion of the engine 14 and is bent and extends rearward of the vehicle body. The intake pipe 18 is provided with a throttle body 19 containing a throttle valve and an IACV (described later). An air cleaner 20 is connected to the rear of the throttle body 19. A fuel injection valve (see FIG. 3) is provided in the intake pipe 18 between the engine 14 and the throttle body 19.

  An accelerator grip (not shown) is provided at the right end of the steering handle 7 of the motorcycle 1. The accelerator grip is attached to the end of the pipe member that forms the steering handle 7 so as to be rotatable.

  FIG. 3 is a system configuration diagram of the engine control apparatus according to the present embodiment, and the same reference numerals as those in FIG. 2 denote the same or equivalent parts. The engine 14 is provided with an intake pipe 18 and an exhaust pipe 21, and a throttle body 19 provided in the intake pipe 18 bypasses the throttle valve 22 and the throttle valve 22, and the intake pipe 18 on both sides of the throttle valve 22. Are connected to each other, and an IACV 24 that opens and closes the bypass passage 23 is provided. A fuel injection valve 25 is provided between the engine 14 and the throttle body 19 on the intake pipe 18.

  The throttle valve 22 is rotated according to the rotation operation of the accelerator grip, and the rotation amount (angle) is detected by the throttle sensor 26. The engine 14 is provided with a water temperature sensor 27 that detects the engine cooling water temperature, and the intake pipe 18 is provided with a PB sensor 28 that detects intake negative pressure. The engine head or exhaust pipe 21 is provided with an O2 sensor 29 that detects the oxygen concentration in the exhaust. The O2 sensor can be made heaterless by being attached to the vicinity of the engine of the exhaust pipe 21 or the engine head. A vehicle speed sensor 30 that detects the vehicle speed from the rotation speed of the output gear of the speed reduction mechanism 16 is provided. The starter switch 33 is a switch for starting the engine 14 by operating an ignition key. Further, an atmospheric pressure sensor 34 is provided at a position far from the intake pipe 18 of the air cleaner 20. The atmospheric pressure sensor 34 may be omitted, and the atmospheric pressure may be estimated based on the detection output of the PB sensor 28.

  An engine control unit (ECU) 31 having a microcomputer (CPU) receives detection signals from a throttle sensor 26, a water temperature sensor 27, a PB sensor 28, and an O2 sensor 29, and an engine start signal and an engine stop signal from a starter switch 33. Entered. The ECU 31 calculates the opening degree of the IACV 24 and the fuel injection amount by the fuel injection valve 25 based on the input detection signal, and inputs them to the IACV 24 and the fuel injection valve 25, respectively.

  Further, the ECU 31 satisfies a predetermined stopping condition such that the vehicle speed detected by the vehicle speed sensor 30 is zero or less than a predetermined speed, and the throttle opening detected by the throttle sensor 26 is zero or less than a predetermined value. There is an idle stop control function for starting the engine 14 when a predetermined idle stop start condition is satisfied, such as when the engine 14 is sometimes stopped and then the throttle valve is opened. In the engine stop in the idle stop control, only the fuel supply by the fuel injection valve 25 is stopped, and an ignition operation by an ignition device (not shown) is continuously performed.

  The ECU 31 has functions other than the control of the IACV 24 and the fuel injection valve 25 and the idle stop control (for example, the ignition timing of the ignition device), but the description thereof is omitted because it is not a main part of the present invention.

  FIG. 4 is a main flowchart relating to the control of the IACV 24 performed by the ECU 31. In step S1 of FIG. 4, it is determined whether the engine is in the engine start mode or other than when the engine is started (basic mode). If it is determined in step S1 that the basic mode is set, the process proceeds to step S2 to determine whether or not the throttle valve 22 is fully closed. When it is determined in step S2 that the throttle valve 22 is fully closed, the process proceeds to step S3, where the engine speed is fed back and the basic opening IFB of the IACV 24 is calculated.

  In step S4, the basic opening degree IFB is corrected to shift to a feedback mode for obtaining the opening degree target value ICMD of the IACV 24. When the determination in step S2 is negative, that is, when it is determined that the throttle valve 22 is not fully closed, the process proceeds to step S5 to shift to the travel mode of the throttle opening degree IACV24.

  If it is in the engine start mode, the process proceeds from step S1 to step S6 to determine whether the engine is started by turning on the starter switch (SW) 33 (Yes), or by starting by opening the throttle valve 22 during idling stop. Judgment is made (No). When it is determined that the starter switch 33 is started by turning on the starter switch 33, the process proceeds to step S7 to perform the normal start mode process. If it is determined that the engine is in the idle stop mode, the process proceeds to step S8 to perform the idle stop (IS) start mode process.

  In the feedback mode of step S4, the opening target value ICMD of the IACV 24 is calculated using Equation 1. ICMD = IFB × KIPA (Formula 1).

  In the travel mode of step S5, the opening target value ICMD of the IACV 24 is calculated using Equation 2. ICMD = (IXREF + ITW) × KIPA (Formula 2).

  In the normal start mode in step S7, the opening target value ICMD of the IACV 24 is calculated using Equation 3. ICMD = (IXREF + ITWS) × KIPA (Formula 3).

  Further, in the idle stop start mode in step S8, the opening target value ICMD of the IACV 24 is calculated using Equation 4. ICMD = (IXREF + ITWS-IS) × KIPA (Expression 4).

  In Expressions 1 to 4, the sign KIPA is an atmospheric pressure correction coefficient, and the sign IXREF is a learning value of the idle air amount in consideration of the aging deterioration of the IACV 24 and the like. Reference numerals ITW, ITWS, and ITWS-IS are water temperature correction coefficients corresponding to the cooling water temperature.

  FIG. 5 is a flowchart for calculating the water temperature correction coefficient. In step S10 of FIG. 5, the water temperature correction coefficient ITW of the travel mode corresponding to the engine water temperature is searched with reference to the water temperature TW-water temperature correction coefficient T_ITW table. In step S11, the water temperature correction coefficient ITWS in the normal start mode corresponding to the engine water temperature TW is searched with reference to the water temperature TW-water temperature correction coefficient T_ITWS table. In step S12, the water temperature correction coefficient ITWS-IS in the idling stop start mode corresponding to the engine water temperature TW is searched with reference to the water temperature TW-water temperature correction coefficient T_ITWS-IS table.

  FIG. 6 is a diagram illustrating an example of a table for searching for a water temperature correction coefficient. In FIG. 6, the horizontal axis represents the water temperature TW detected by the water temperature sensor 27, and the vertical axis represents the water temperature correction coefficient corresponding to the water temperature TW. As can be understood from FIG. 6, the table is set so that the water temperature correction coefficient takes a large value in the order of the travel mode, the idle stop start mode, and the normal start mode. Therefore, the target opening value of the IACV calculated by the equations 2, 3, and 4 using the water temperature correction coefficients ITW, ITWS, ITWS-IS set in this way is the largest in the normal start mode, Next, the idling stop start mode and the traveling mode become smaller in order. In other words, the amount of air supplied to the engine 14 through the IACV 24 at the start of idling stop is smaller than the amount of air supplied to the engine 14 through the IACV 24 at the normal start. Therefore, when the throttle valve 22 is opened during the idle stop control and the engine 14 is started, the tendency that the intake air amount becomes excessive and the air-fuel mixture becomes lean can be corrected.

  FIG. 7 is a diagram illustrating an example of a search table for the atmospheric pressure correction coefficient KIPA. In the figure, the horizontal axis represents the atmospheric pressure PA detected by the atmospheric pressure sensor 34, and the vertical axis represents the atmospheric pressure correction coefficient KIPA. As shown in FIG. 7, since the table is set so that the atmospheric pressure correction coefficient KIPA becomes larger as the atmospheric pressure PA is lower, the atmospheric pressure PA becomes lower and the insufficient air amount can be compensated.

  FIG. 1 is a block diagram illustrating functions related to the IACV control unit of the ECU 31. In FIG. 1, the water temperature correction coefficient ITWS-IS corresponding to the water temperature TW is set in the water temperature correction value table (second correction coefficient table) 35 at the time of idling (IS) start-up, and is detected by the water temperature sensor 27. Based on the water temperature TW, the water temperature correction coefficients ITWS and ITWS-IS are read out.

  In the normal start time water temperature correction value table (first correction coefficient table) 36, a water temperature correction coefficient ITWS corresponding to the water temperature TW is set. The switching unit 37 switches between the idling start time water temperature correction value table 35 and the normal start time water temperature correction value table 36 based on the determination result of the start mode determination unit 38, and changes the water temperature correction coefficient ITWS-IS or ITWS to the IACV opening target. Input to the value calculator 39.

  The start mode discriminating unit 38 discriminates whether the start operation by the starter switch 33 has been performed, or whether the throttle valve 22 has been opened from the fully closed state by the throttle open detecting unit 41 during idling stop by the idle stop control unit 40. The switching unit 37 selects the normal start water temperature correction value table 36 during the start operation by the starter switch 33 and selects the idling start water temperature correction value table 35 during the opening operation of the throttle valve 22 during idling stop. Switch.

  The input learning value IXREF, the atmospheric pressure correction coefficient KIPA, and the water temperature correction coefficient (ITWS, ITWS-IS) are used in the IACV opening target value calculation unit 39, and the IACV opening target value is calculated according to Equations 3 and 4. ICMD is calculated. The calculated IACV opening target value ICMD is supplied to the driver 42 of the IACV 24. The driver 42 drives and controls the step motor provided in the IACV 24 according to the IACV opening target value.

  Next, a second embodiment of the present invention will be described. In the first embodiment, in order to optimize the air-fuel ratio of the air-fuel mixture during the idling stop control, the water temperature correction coefficient at the time of starting the engine is changed separately from that at the time of normal starting. In the second embodiment, in addition to the control of the first embodiment, the air-fuel ratio detected by the oxygen concentration detected by the O2 sensor (oxygen concentration) 29 is fed back to the fuel injection amount by the fuel injection valve 25 to return the air-fuel ratio. An example of optimizing Conventionally, the learning value of the O2 feedback coefficient KO2 calculated based on the detected value of the O2 sensor 29 is cleared at the time of initial or engine stop, so when the engine is stopped by the idle stop control, The feedback control is started from the state where the feedback coefficient KO2 is “1.0”. Therefore, the air-fuel ratio may tend to be rich for a while from the start.

  Therefore, in the second embodiment, during the idle stop control, the learning value is held without clearing the O2 feedback coefficient KO2 when the engine is stopped.

  FIG. 8 is a timing chart of O2 feedback. In the upper part of FIG. 8, the engine stall is indicated by “1” and the engine rotation is indicated by “0”. In the middle row, “1” indicates that O2 feedback control is being executed, and “0” indicates that O2 feedback control is stopped. Also, the lower part shows the change of the O2 feedback coefficient KO2.

  As shown in FIG. 8, when the engine 14 is stopped during the idle stop control at the timing t1, the O2 feedback control is also stopped. Then, the engine 14 is started by idle stop control at timing t2. However, the O2 feedback control is not started at the timing t2, and the O2 feedback control is started at the timing t3 when the detection output of the O2 sensor 29 is stabilized. The time T between t2 and t3 may be a fixed time by a timer or a variable value in consideration of the cooling water temperature.

  Conventionally, the O2 feedback coefficient KO2 is cleared to “1.0” at the timing t1 when the O2 feedback control is stopped, but in this embodiment, learning of the O2 feedback coefficient when the engine is stopped (time t1). A value (“0.85” as an example) is held, and at the timing t3, the held O2 feedback coefficient KO2 is read to restart the O2 feedback control.

  According to this, since the optimum O2 feedback coefficient O2 can be used from the start of the O2 feedback control, compared with the case where the O2 feedback coefficient KO2 reset to “1.0” is used, in the area A of FIG. The fuel consumption can be improved as much as shown.

  FIG. 9 is a flowchart of O2 feedback control when the engine is stopped. In step S20, it is determined whether the engine 14 has stopped. If it is determined that the engine 14 has stopped, the process proceeds to step S21. In step S21, it is determined whether the engine is stopped by idle stop control or the engine is stopped by turning off the power by turning off the starter switch 33. If the engine 14 is stopped by the idle stop control, the process proceeds to step S22, and the O2 sensor feedback coefficient KO2 is held. If the engine 14 is stopped due to turning off the starter switch 33, the process proceeds to step S23, and the O2 feedback coefficient KO2 is reset to “1.0”.

  FIG. 10 is a flowchart of O2 feedback control at the time of engine start. In step S30, it is determined whether the engine is started from a stop state by idle stop control or is a normal start by the starter switch 33. In the case of starting from the stop state by the idle stop control, the process proceeds to step S31, and the holding value (for example, “0.85”) of the O2 feedback coefficient KO2 is read. If it is a normal start by the starter switch 33, the process proceeds to step S32 and "1.0" is read as the feedback coefficient KO2.

  In step S33, it is determined whether or not the output of the O2 sensor 29 is stable, that is, whether or not the time T has elapsed. If step S33 is positive, the process proceeds to step S34, where feedback control using the O2 feedback coefficient KO2 is performed, and the fuel injection amount by the fuel injection valve 25 is calculated.

  The fuel injection amount is obtained by the fuel injection pulse width, that is, the fuel injection time Ti within a predetermined unit time. The fuel injection time Ti is calculated using, for example, the following equation. Ti = Tp × KTW × KO2 + TS (Formula 5).

  In Equation 5, Tp is a basic injection pulse width calculated based on the intake air amount Q and the engine speed Ne, KTW is a correction coefficient for correcting an increase in fuel according to the water temperature TW, and KO2 is a feedback coefficient.

  In step S35, an O2 feedback coefficient KO2 is calculated based on the detection output of the O2 sensor 29. In step S36, the O2 feedback coefficient KO2 is updated.

  FIG. 11 is a block diagram illustrating main functions of the ECU 31 according to the second embodiment. In FIG. 11, the O2 feedback control unit 43 calculates the O2 feedback coefficient KO2 based on the detection signal of the O2 sensor 29, and calculates the fuel injection amount by the fuel injection valve 25 using the O2 feedback coefficient KO2. The O2 feedback coefficient KO2 is stored in the coefficient storage unit 44.

  The idle stop control unit 45 temporarily stops the engine 14 when a predetermined stop condition is satisfied, and starts the engine 14 when a predetermined condition for starting such as an opening operation of the throttle valve 22 is satisfied. . The idle stop control is performed according to known conditions.

  The engine stop determination unit 46 determines whether the engine 14 is stopped by idle stop control or the starter switch 33 is turned off. If the engine is stopped by the idle stop control, the feedback coefficient KO2 stored in the coefficient storage unit 44 is held as it is. If the engine is stopped by the starter switch 33, “1.0” is stored in the coefficient storage unit 44 as the O2 feedback coefficient KO2.

  When the engine is started and O2 feedback control is started, first, the O2 feedback coefficient KO2 is read from the coefficient storage unit 44.

  DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 14 ... Engine, 18 ... Intake pipe, 19 ... Throttle body, 22 ... Throttle valve, 24 ... IACV, 26 ... Throttle sensor, 27 ... Water temperature sensor, 29 ... O2 sensor, 31 ... ECU, 33 ... Starter 35, second correction coefficient table, 36, first correction coefficient table, 38, start mode determination unit, 39, IACV opening target value calculation unit

Claims (5)

In an engine control device having an idle air amount control valve (IACV) (24) provided in a bypass passage (23) that bypasses the throttle valve (22) and connects the intake pipe (18),
An opening target value for calculating the target opening value of the IACV using a calculation formula that uses a water temperature correction coefficient corresponding to the cooling water temperature of the engine and increases the target opening value of the IACV as the water temperature correction coefficient increases Calculating means (39);
A start mode discriminating means (38) for discriminating whether the engine is started normally by the starter switch (33) or idling stop by the idling stop control;
The water temperature correction coefficient used by the opening target value calculation means (39) is set smaller at the time of idle stop start than at the time of normal start ,
At the time of the idle stop start and the normal start, a large value is obtained by adding the water temperature correction coefficient and the learned value (IXREF) of the idle air amount taking into account the aging deterioration of the idle air amount control valve (24). The opening target value of the IACV is calculated by multiplying the atmospheric pressure correction coefficient (KIPA), which is a larger value as the atmospheric pressure is lower,
In a feedback mode in which the basic opening degree (IFB) of the IACV is feedback controlled based on the oxygen concentration detected by the oxygen concentration sensor, the basic opening degree (IFB) is used without using the learning value (IXREF) of the idle air amount. ) And the atmospheric pressure correction coefficient (KIPA) to calculate the target opening value of the IACV .   2. The engine control device according to claim 1, wherein the idling stop start is performed by an accelerator operation for opening a throttle valve (22). A first correction coefficient table (36) in which a normal start water temperature correction coefficient corresponding to the engine coolant temperature is set;
The engine control device according to claim 1 or 2, further comprising a second correction coefficient table (35) in which a water temperature correction coefficient for idling stop start corresponding to the engine coolant temperature is set. An oxygen concentration sensor (29) for detecting the oxygen concentration in the exhaust;
Control means (43) for performing air-fuel ratio control so that the larger the feedback coefficient, the richer the feedback coefficient, using a feedback coefficient calculated based on the oxygen concentration detected by the oxygen concentration sensor;
Engine stop determining means (46) for determining whether or not the engine is stopped in a state in which the idle stop control is maintained;
Storage means (44) for holding a feedback coefficient at that time when the engine is stopped in a state in which the idle stop control is maintained,
The engine control device according to claim 1, wherein the feedback coefficient held in the storage means (44) is read by the control means (43) when the engine is started during idle stop control.   2. The engine control device according to claim 1, wherein the engine stop in the idle stop control is performed by stopping the fuel supply to the engine and the ignition is continued.

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