JP4622838B2 - Automotive engine control system - Google Patents

Description

  The present invention relates to a control device for an automobile engine provided with an electric supercharger, and more particularly to a technique for improving startability from an idle operation state.

  In recent years, demands for improving fuel consumption are particularly increasing, and as an effective countermeasure, the engine idling speed is decreasing. However, if the idle rotation speed is reduced, the startability may deteriorate when starting from an idle operation state, particularly when starting a relatively large acceleration. This is because the time required to increase the rotational speed of the engine increases and the increase in driving force tends to be delayed.

  In order to solve such a problem, a technique for temporarily reducing the amount of power generated by the alternator is known. The engine output is not always supplied as the driving force of the vehicle, and is usually consumed as a load by various auxiliary machines. In other words, the engine output is distributed to the load by the auxiliary machine and the driving force of the vehicle. An alternator is also a kind of auxiliary equipment, and the load on the engine increases as the amount of power generation increases. Therefore, by temporarily reducing the power generation amount of the alternator and suppressing the engine load, the driving force of the vehicle can be increased without increasing the engine output. This action is used to compensate for the increase in driving force at the start from the idling state.

  For example, Patent Document 1 discloses a technique for reducing the output voltage of an alternator by determining that a relatively large acceleration is required when the engine speed change rate is a predetermined value or more.

  Patent Document 2 discloses a technique for detecting the start from an idle operation state based on a change in engine rotation speed and reducing the amount of power generated by the alternator in such a case.

In addition, an automobile engine equipped with an electric supercharger is known as a prior art related to the present invention. The electric supercharger is a known mechanism that is electrically driven to supercharge intake air. For example, Patent Literature 3 discloses a device that operates an electric supercharger in the early stage of acceleration. Usually, electricity generated by an alternator (including electricity stored in a battery) is used as a drive source for the electric supercharger.
JP 9-327199 A JP 2002-345298 A JP 2004-108152 A

  However, even if the load on the alternator is reduced as described in Patent Documents 1 and 2, the load on the alternator cannot be made smaller than 0, so there is a limit to the reduction allowance. Therefore, there is a case where sufficient startability cannot be obtained or it is difficult to further reduce the idle rotation speed.

  In view of such circumstances, an object of the present invention is to provide an automobile engine control device that can improve the startability from the idling operation state even when the idling rotational speed is reduced.

The invention according to claim 1 for solving the above-described problem is an electric supercharger that is electrically driven to supercharge intake air, and an electric supercharger control means that controls the driving of the electric supercharger, An automobile engine control device mounted on a vehicle together with an automatic transmission includes an alternator driven by engine power and target current control means for adjusting a target output current value of the alternator. A rotation speed detection means; a brake operation detection means for detecting a brake operation state of the vehicle; and an accelerator operation detection means for detecting an accelerator operation state of the vehicle, wherein the engine is operating at a predetermined idle rotation speed. off and the first time it is from the state of the brake on the brake off, the electric supercharger control means drives the electric supercharger engine Rutotomoni increase the force, the target current control means increases the target output current value of the alternator to the first target value to increase the engine load so as to cancel the engine output increases, then, is the accelerator-on At the second time point, the target current control means forcibly reduces the target output current value of the alternator to the second target value while preventing the increased engine output from being reduced, thereby reducing the engine load. The starting driving force increase control for obtaining the driving force is performed.

  The brake does not necessarily indicate only a foot brake, but indicates all brakes for stopping the vehicle from starting. For example, a side brake is also included in the brake. Brake off means a state in which all brakes are released.

  According to a second aspect of the present invention, in the automobile engine control apparatus according to the first aspect, the first target value is set to a constant value equal to or greater than a current consumption of the electric supercharger.

  The current consumption is not necessarily the maximum current consumption corresponding to the rating of the electric supercharger, but is a current value that is appropriately set below the maximum current consumption.

  According to a third aspect of the present invention, in the engine control apparatus for an automobile according to the first or second aspect, the intake flow rate adjusting means for adjusting the intake flow rate is provided, and the intake flow rate adjusting means increases the intake flow rate at the first time point. And controlling to increase the engine speed.

  According to a fourth aspect of the present invention, in the automobile engine control apparatus according to any one of the first to third aspects, the second target value is a predetermined constant value.

  According to a fifth aspect of the present invention, in the automobile engine control device according to any one of the first to third aspects, the vehicle is provided with an acceleration request level determination unit that determines a vehicle acceleration request level from the accelerator operation state. The second target value is set to a smaller value as the degree of acceleration request at the second time point is larger.

According to a sixth aspect of the present invention, in the automobile engine control device according to any one of the first to fifth aspects, the second target value is determined when the vehicle is traveling in a light extinction state at least under a predetermined condition. The value is smaller than the average current consumption of the vehicle.

  According to a seventh aspect of the invention, in the automobile engine control device according to any one of the first to sixth aspects, when the accelerator is not turned on even after a predetermined time has elapsed from the first time point, The charger control means gradually reduces the rotational speed of the electric supercharger, and the target current control means gradually reduces the target output current value of the alternator from the first target value. .

  According to an eighth aspect of the present invention, in the vehicle engine control device according to any one of the first to third aspects, the brake operation detecting means detects the speed of the brake off operation at the first time point. In addition, when the speed of the brake-off operation is relatively slow, the electric supercharger control means prohibits the driving of the electric supercharger by the electric supercharger control means or makes the driving force state and the target An increase in the target output current value of the alternator by the current control means is suppressed.

  According to the first aspect of the present invention, as described below, even when the idle rotation speed is lowered, the startability from the idle operation state can be improved.

  In the present invention, as a normal driving operation of an automobile equipped with an automatic transmission, the brake is turned on and the accelerator is turned off during idling, and the brake is first released (turned off) at the start (first). At that time, the accelerator is then turned on (second time point). Then, at the first time point where the accelerator is not turned on, it is assumed that the accelerator will be turned on soon, and the preparation is made.

  In the starting drive force increase control of the present invention, the engine output is increased by the electric supercharger control means driving the electric supercharger at the first time point when the brake is released. On the other hand, when the target current control means increases the target output current value (power generation amount) of the alternator to the first target value, the driving force of the alternator, that is, the engine load increases. The increase in the load cancels out part or all of the increase in the engine output, and the fluctuation of the driving force of the vehicle transmitted to the driving wheels via the automatic transmission is suppressed.

  In order to prevent the driver from feeling uncomfortable, it is desirable that the fluctuation of the driving force of the vehicle is small. For this purpose, the increase in output torque due to the electric supercharger may be balanced with the increase in load due to the increase in power generation amount, and the increase / decrease in output torque (for example, increase / decrease in throttle opening) or the increase / decrease in load separately. You may balance by using together.

  Next, when the accelerator is turned on, that is, depressed at the second time point, the target current control means forcibly reduces the target output current value of the alternator to the second target value. As a result, the load on the engine is reduced, and the engine output torque corresponding to the reduction is instantaneously provided to the driving force of the vehicle. Therefore, the start driving force of the vehicle can be increased without waiting for the engine operating state to change (engine output torque or rotational speed increases). That is, startability can be improved.

  Here, by increasing the power generation amount of the alternator at the first time point in advance, it is possible to expand the reduction amount of the power generation amount at the second time point as compared with the case where this is not performed. Therefore, it is possible to increase the starting driving force increase margin of the vehicle accompanying the accelerator on, which is more advantageous for improving the starting performance.

  By the way, when the power generation amount of the alternator is simply increased at the first time point, the surplus power is charged in the battery. However, if the battery is fully charged, if the amount of power generation is forcibly increased, the battery may be overcharged. However, in the present invention, the electric supercharger is driven at the first time point. As a result, the increased power generation amount can be consumed by the electric supercharger, so that overcharging of the battery can be prevented.

  An electric supercharger is generally a device that consumes more power than other electrical components. Therefore, the increase amount of the power generation amount can be made relatively large, and the reduction amount of the power generation amount at the second time point can be made larger.

  According to the second aspect of the invention, by setting the first target value to a constant value, it becomes easy to make the acceleration feeling constant when the accelerator is on, and it is easy to suppress the driver's uncomfortable feeling. It is desirable to set the first target value as large as possible while avoiding overcharging. Therefore, the first target value is preferably equal to or greater than the current consumption of the electric supercharger, more specifically, the sum of the average current consumption of the vehicle during normal driving when the light is extinguished and the current consumption of the electric supercharger. is there.

  According to the invention of claim 3, by increasing the intake air flow rate at the first time point and increasing the engine rotation speed in advance, the engine rotation speed can be already increased at the second time point when the accelerator is turned on. . That is, since the engine rotation speed is increased prior to the case where the start driving force increase control is not performed, higher startability can be obtained.

  In addition, one knock can be suppressed by increasing the intake flow rate. One-shot knocking is a short-time knocking that occurs at a low speed and a high load, and is likely to occur at the moment when the user tries to start by relatively stepping on the accelerator. This one-shot knock hardly affects the durability of the engine, but it is accompanied by an abnormal noise. In order to suppress one-shot knock, conventionally, an ignition retard that temporarily delays the ignition timing has been generally performed. By performing the ignition retard, the combustion temperature is lowered and knocking is suppressed. However, if ignition retard is performed in order to suppress one-shot knock, the engine torque is reduced, which is a factor that hinders improvement in startability.

  According to the present invention, the occurrence of a single knock can be suppressed by increasing the engine rotation speed at the first time point, that is, by increasing the engine speed. This effect becomes more prominent as the idle rotation speed decreases.

  Another factor that makes it easy to make a single knock is a rise in intake air temperature. Since the intake air is throttled during idle operation, the air is stagnant in the intake passage (mainly in the surge tank). Accordingly, the residence time of the intake air in the high temperature engine room becomes longer, and the intake air temperature rises. When the accelerator is turned on in this state and the throttle opening increases suddenly, hot intake air flows into the cylinder at once, and the temperature rises further due to rapid compression of the air in the cylinder. It becomes.

  On the other hand, according to the present invention, by increasing the engine speed at the first time point, that is, by increasing the intake air flow rate, the time during which the intake air stays in the high-temperature engine room can be shortened. . That is, the intake air temperature can be reduced in advance. Therefore, an increase in the combustion temperature when the accelerator is turned on at the second time point thereafter is suppressed, and a single knock is less likely to occur.

  Thus, since one knock is suppressed, the retard amount (ignition delay margin) of the ignition retard for suppressing the one knock can be reduced. Accordingly, a decrease in engine torque due to ignition retard can be suppressed, and the startability can be further improved.

  When driving the electric supercharger, it is necessary to consider so that surging does not occur. Surging is more likely to occur as the intake air flow rate decreases if the conditions such as the supercharging pressure are the same. According to the present invention, the intake air flow rate is increased together with the driving of the electric supercharger at the first time point, which is advantageous for suppressing surging.

  According to the invention of claim 4, by setting the second target value to a constant value, it becomes easy to make the acceleration feeling constant when the accelerator is on (second time point), and the driver feels uncomfortable. It becomes easy. In particular, when the first target value is also a constant value (see claim 2), the amount of reduction in power generation at the second time point (first target value-second target value) is made constant, making the driver more uncomfortable. The suppression effect can be enhanced.

  According to the invention of claim 5, as the acceleration request degree is larger, the power generation amount reduction margin at the second time point is increased, that is, the starting driving force of the vehicle can be increased, so that it corresponds to the driver's acceleration request degree. The vehicle can be started with acceleration.

  According to the invention of claim 6, the power generation amount reduction allowance at the second time point can be increased as necessary. That is, since the driving force of the vehicle at the start can be further increased, the startability can be improved more flexibly.

  According to the seventh aspect of the present invention, when the accelerator is not turned on within a predetermined time after the brake is released at the first time point, the rotational speed of the electric supercharger and the power generation amount of the alternator are reduced (finally, the original (It is desirable to return to the idling operation state), so that the fuel consumption can be improved as compared with the case where it is not reduced. Moreover, the unpleasant feeling given to a driver | operator can be suppressed by making it reduce gradually. The predetermined time is preferably set sufficiently longer than a general time (within 0.3 to 0.5 seconds) required from the first time point to the second time point when starting with a high degree of acceleration request (for example, 2 to 2). 5 seconds).

  According to the invention of claim 8, when the brake release at the first time point is operated gently, there is very little shift to sudden acceleration immediately after that. While the driving of the feeder itself is prohibited or in a weak driving force state, an increase in the target output current value of the alternator is suppressed, and deterioration in fuel consumption during this period can be suppressed.

  In addition, in a powertrain in which an automatic transmission is connected to the engine body, when the brake release is operated gently, the electric turbocharger itself is prohibited or weakly driven, so the engine speed Can be suppressed, and extremely low-speed creep running can be secured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic block diagram including an automobile engine control apparatus according to an embodiment of the present invention. An automatic transmission 50 is connected to the engine body 1. Further, drive wheels (not shown) are connected to the output shaft of the automatic transmission 50.

  The engine body 1 is provided with a crank angle sensor 30 (rotational speed detecting means), which detects the rotational speed of a crankshaft (not shown), that is, the engine rotational speed.

  A throttle valve 23 driven by an actuator 24 is disposed in the intake passage 21 of the engine body 1. The throttle valve 23 constitutes an intake air flow rate adjusting means together with a throttle opening degree control unit 2b described later. Further upstream of the throttle valve 23, an electric supercharger 26 and an air flow sensor 25 for detecting the intake air flow rate are provided.

  The electric supercharger 26 is a supercharger that is electrically driven to supercharge intake air. Although its structure is well known and will be described briefly, it is mainly composed of a compressor provided in the intake passage 21 and an electric motor for driving the compressor. The electric motor rotates the compressor based on a drive signal from an electric supercharger control unit 2a described later. In this embodiment, a motor with a rating of 1.2 kW is used. The drive source is electricity (including electricity stored in the battery 55) generated by an alternator 28 described later.

  An alternator 28 (generator) is attached to the engine body 1. Since the structure of the alternator 28 is well known, it will be described briefly. However, the output voltage is adjusted by controlling the excitation current of a field coil (not shown) driven by the engine via the belt 27 by a regulator circuit, and a predetermined power generation amount (target output) Current). The driving force of the alternator 28 acts as an engine load.

  The electricity generated by the alternator 28 is supplied to an electric drive unit (so-called electrical component) (not shown) in addition to the electric supercharger 26 described above, and the battery 55 is charged if there is a remainder. The electricity stored in the battery 55 is supplied to the electric supercharger 26 and other electric drive units as necessary.

  In addition, an accelerator opening sensor 34 (accelerator operation detecting means) for detecting the depression amount of an accelerator pedal (not shown) and a brake switch 35 (brake operation detecting means) for detecting on / off of a brake are provided on the vehicle side. ing. When there are a plurality of brake systems, a brake switch 35 is provided for each system. For example, when a foot brake (not shown) and a side brake (not shown) are provided, a total of two brake switches 35 are provided for each brake.

  The ECU 2 is provided as a control unit that controls the combustion of the engine, the auxiliary machinery, or the operation of the electric supercharger 26. The ECU 2 includes a computer having a CPU, a ROM, a RAM, and the like. Specifically, various operations and the like are controlled by executing a program stored in the ROM (or RAM) in advance by the CPU. The ECU 2 is supplied with power from the battery 55 as shown. The ECU 2 receives various signals from the air flow sensor 25, the crank angle sensor 30, the accelerator opening sensor 34, and the brake switch 35, and sends them to the actuator 24, the electric supercharger 26, an ignition plug, a fuel injection device, etc., not shown. Send drive signal.

  The automobile engine control device of the present embodiment is configured to perform start driving force increase control for increasing the start driving force when the vehicle starts. FIG. 1 shows an electric supercharger control unit 2a, a throttle opening control unit 2b, a fuel supply control unit 2c, an ignition control unit 2d, and an alternator power generation amount that are functionally included in the ECU 2 in order to perform start driving force increase control. The control part 2e and the acceleration request | requirement degree determination part 2g are shown in figure.

  The electric supercharger control unit 2a (electric supercharger control means) usually determines whether or not supercharging is necessary based on detection values of the crank angle sensor 30 and the accelerator opening sensor 34, and performs supercharging. Set the rotation speed of the compressor. Then, the drive signal is sent to the electric motor of the electric supercharger 26.

  Further, when the starting driving force increase control is executed, the electric supercharger control unit 2a is configured so that the brake is turned on (at least one brake switch 35 is turned on, the same applies hereinafter) to the off (all brake switches 35) during the idle operation. Is switched off (the same applies hereinafter)) (first time point), the electric supercharger 26 is driven at a predetermined rotational speed.

  The throttle opening control unit 2b constitutes an intake flow rate adjusting means together with the throttle valve 23 described above. The throttle opening control unit 2b normally sets a required throttle opening based on a detection value of the accelerator opening sensor 34, etc., and outputs a drive signal to the actuator 24 to adjust the opening K of the throttle valve 23. For example, during normal idling (accelerator opening Ac = 0%), the throttle opening K = 0%.

  Further, when the start driving force increase control is executed, the throttle opening degree control unit 2b increases the throttle opening degree K at the first time point. That is, the intake flow rate is increased.

  The fuel supply control unit 2c receives the detection value from the air flow sensor 25, and sets the amount of fuel that becomes a predetermined air-fuel ratio corresponding to the operation state with respect to the intake flow rate. For example, in the case of a direct injection engine, a drive signal is sent to a fuel injection device (not shown) to inject a predetermined amount of fuel at a predetermined time (for example, late in the intake stroke).

  When the start driving force increase control is executed, the supercharging pressure and the intake air flow rate are increased at the first time point as described above, and accordingly, the fuel supply control unit 2c increases the fuel supply amount accordingly. As a result, the combustion energy increases, so the engine output torque increases and the rotational speed increases.

  The ignition control unit 2d sets an appropriate ignition timing according to the operating state, sends an ignition signal to an ignition plug (not shown), and ignites it.

  When the starting driving force increase control is executed, after the first time point, the accelerator is switched off (accelerator opening Ac = 0%, the same applies hereinafter) to on (accelerator opening Ac> 0%, the same applies below), and the driver When the acceleration request degree (details will be described later) is large, the ignition control unit 2d performs ignition retard and reduces the combustion temperature to suppress one-shot knock.

  The alternator power generation amount control unit 2e (target current control means) sets the alternator power generation amount Alt (target output current value) according to the operating state, and adjusts the excitation current of the regulator circuit so as to obtain the target output current. . As the alternator power generation amount Alt increases, a larger driving force is required, and the engine load increases.

  When the start driving force increase control is executed, the alternator power generation amount control unit 2e increases the alternator power generation amount Alt to the first target value at the first time point when the brake is released during the idle operation, and then the accelerator is switched from OFF to ON. When the driver's degree of acceleration request is large, the alternator power generation amount Alt is reduced to the second target value.

  The acceleration request level determination unit 2g (acceleration request level determination means) determines the magnitude of the acceleration request level in the starting driving force increase control. At the time of determination, the acceleration request degree determination unit 2g first determines that the accelerator opening change rate DA (accelerator opening per unit time) based on the detected value of the accelerator opening sensor 34 when the accelerator is switched from off to on during idling. Change amount of degree Ac). When the accelerator opening change rate DA is greater than or equal to a predetermined value, it is determined that the driver is requesting a relatively large acceleration at the time of starting, that is, the acceleration request degree is large.

  Next, the operation of the automotive engine control apparatus of the present embodiment will be described focusing on the starting driving force increase control.

  FIG. 2 is a time chart showing a state when the vehicle starts from the idle operation state. The horizontal axis represents time, and the vertical axis represents engine rotational speed Ne, alternator power generation amount Alt, electric supercharger rotational speed Ns, throttle opening K, accelerator opening Ac, and brake operation state. Then, engine speed Ne characteristic 101, alternator power generation amount Alt characteristic 111 (target value is indicated by characteristic 115), electric supercharger rotation speed Ns characteristic 121 (target value is indicated by characteristic 123), throttle opening A characteristic 131 of degree K, a characteristic 141 of accelerator opening degree Ac, and a characteristic 151 of brake operation are shown. Note that the characteristics 105 of the engine rotational speed Ne, the characteristics 125 of the electric supercharger rotational speed Ns, and the characteristics 135 of the throttle opening K are referred to refer to characteristics when the start driving force increase control of this embodiment is not performed. It is shown in.

  Before the time point t1 (first time point), the accelerator opening degree Ac = 0% and the brake is on, which is a normal idle operation state. That is, the engine speed Ne = N1 (for example, N1 = 600 rpm) and the throttle opening K = 0%. Further, the alternator power generation amount Alt = Ia (A). The power generation amount Ia is an average current consumption of the vehicle during normal running when the light is extinguished, and shows, for example, a case of about 30A.

  When the brake is released at time t1 (characteristic 151), the throttle opening degree control unit 2b increases the throttle opening degree K from 0% to K1%. As a result, the intake air flow rate increases, and the engine output torque and the rotational speed increase. The throttle opening K1 is an appropriate value that can be maintained by increasing the engine speed Ne from N1 to N2 (for example, N2 = 900 rpm). The throttle opening K1 may be a preset value or may converge the engine speed Ne to N2. Alternatively, adjustment may be performed by feedback control. Since the engine output increases also by driving the electric supercharger 26 described later, the throttle opening K1 is determined including the increase in the output.

  The electric supercharger control unit 2a drives the electric supercharger 26 substantially at the same time as the time t1, preferably at a time t1 'after a short time (for example, after 0.1 s). The power consumption of the electric supercharger 26 can be set as appropriate in a range of rated (1.2 kW) or less and in a region where surging does not occur. When the voltage is 13.5V, the maximum current consumption is about 90A. In this embodiment, the current consumption is set to 35A. The electric supercharger rotational speed N6 at that time is N6 = 50000 rpm. By driving the electric supercharger 26, the supercharging pressure rises and the engine output increases.

  Further, at the time point t1 ', the alternator power generation amount control unit 2e increases the target power generation amount (target output current value) of the alternator 28 to the first target value Ib (A) (characteristic 115). In the present embodiment, the first target value Ib is a constant value obtained by adding the consumption current (for example, 35 A) of the electric supercharger 26 to the average consumption current (about 30 A) of the vehicle during normal driving when the light is extinguished. About 65A). Increasing the alternator power generation amount Alt increases the load on the engine by the auxiliary machine. In this embodiment, the increase in engine output torque due to the increase in the intake air flow rate and the increase in the supercharging pressure balances with the increase in engine load due to the increase in alternator power generation amount Alt, resulting in substantial fluctuations in the drive torque of the vehicle. It is set so as not to occur.

  Note that a slight time difference is provided between the time point t1 and the time point t1 ′ because the increase in the engine speed Ne is increased by slightly increasing the throttle opening K before the increase in the alternator power generation amount Alt. This is to make the process smoother and faster. The first time point in the present invention includes a time point t1 '.

  Subsequently, the accelerator is depressed at time t2 (second time point) (characteristic 141). When the driver's acceleration request degree is large, the time point t2 is usually 0.3 to 0.5 s after the time point t1.

  At the time point t2, the acceleration request degree determination unit 2g determines the acceleration request degree based on the characteristics 141 of the accelerator opening degree Ac. In the present embodiment, the rate of change DA of the accelerator opening Ac is calculated, and it is assumed that the greater the accelerator opening change rate DA is, the greater the degree of acceleration request is. When the accelerator opening change rate DA> predetermined value a1, the alternator power generation amount control unit 2e reduces the target power generation amount of the alternator power generation amount Alt to a second target value Ic lower than the first target value Ib. The alternator 28 is highly responsive in the direction of reducing the power generation amount, and the actual power generation amount is rapidly reduced (characteristic 111).

  When the alternator power generation amount Alt is reduced at time t2, the engine output torque corresponding to the reduction allowance (Ib-Ic) is instantaneously supplied as the vehicle starting drive force. Therefore, the start driving force of the vehicle increases without waiting for the engine operating state to change (the engine output torque or the rotational speed Ne increases). Thus, it is possible to easily start with acceleration according to the driver's request. That is, startability is improved.

  Here, since the alternator power generation amount Alt is increased to the first target value Ib in advance, the reduction allowance (Ib-Ic) is the reduction allowance when the alternator power generation amount Alt is not increased (Ia-Ic). Can be larger. Moreover, the electric supercharger 26 is generally a device that consumes more power than other electrical components. Therefore, the first target value Ib can be made relatively large, and the reduction allowance (Ib−Ic) can be made larger.

  Although FIG. 2 shows the case where the second target value Ic is smaller than the power generation amount Ia at the time point t1, the setting may be equal to or greater than the power generation amount Ia. The minimum value of the second target value Ic can be set to 0 (A). The greater the reduction amount (Ib-Ic) of the alternator power generation amount Alt, the greater the effect of increasing the starting driving force. In the present embodiment, the first target value Ib is set to a constant value, and as the accelerator opening change rate DA is larger, that is, as the degree of acceleration request is larger, the second target value Ic is decreased to generate the alternator power generation amount Alt. The reduction allowance (Ib-Ic) is increased. By doing so, it is possible to start the vehicle with acceleration according to the degree of acceleration demand of the driver.

  Alternatively, both the first target value Ib and the second target value Ic may be predetermined constant values. In this case, the acceleration feeling when the accelerator is on is made constant, and the driver can be prevented from feeling uncomfortable.

  For example, when the power generation amount Ia = 30A, Ib = 65A, and Ic = 30A (= Ia), the reduction amount (Ib−Ic) of the alternator power generation amount Alt corresponds to an increase of about 9 N · m in engine torque ( Ne = N2 and the efficiency of the alternator 28 is 0.57). Further, when Ic = 0 A, the reduction amount (Ib−Ic) of the alternator power generation amount Alt corresponds to an increase of about 16.4 N · m of the engine torque. This is because the engine torque corresponding to the maximum value (30A) of the reduction amount (Ia-Ic) of the alternator power generation amount Alt when the start driving force increase control is not performed, approximately 11.3 N · m (Ne = N1) ) 1.4 times or more.

  In addition, although the consumption current of the electric supercharger 26 at the time point t1 ′ is set to 35 A, a bypass passage (not shown) of the electric supercharger 26 is provided, and the consumption current of the electric supercharger 26 is about 90 A which is the maximum. (Electric supercharger rotational speed N6 is set to about 75000 rpm), and this bypass passage may be opened somewhat so that surging does not occur. In this case, the first target value Ib of the alternator power generation amount Alt can be set to about 90 A, and the reduction amount (Ib-Ic) of the alternator power generation amount Alt corresponds to an increase of about 16.4 N · m of the engine torque. The reduction amount (Ib-Ic) of the alternator power generation amount Alt when Ic = 0 A corresponds to an increase of about 22.5 N · m of the engine torque, and an acceleration feeling can be obtained accordingly.

  In addition, when the power generation amount of the alternator 28 is simply increased at the time t1 ′, there is a risk of overcharging if the battery 55 is fully charged. However, in this embodiment, the increased power generation amount is generated by the electric supercharger 26. Since it is consumed, overcharging of the battery 55 is prevented.

  Further, according to the start driving force increase control, the engine pressure is already increased at the time point t2 when the accelerator is turned on by increasing the boost pressure and the intake air flow rate at the time points t1 to t1 ′ and increasing the engine output. The output torque and the rotational speed Ne are increased. That is, the engine output torque and the rotational speed are increased in advance of the case where the start driving force increase control is not performed (characteristic 105). This is also advantageous for improving startability.

  In addition, since the intake air flow rate is increased at time t2, it is advantageous for suppressing surging during supercharging.

  Further, the start driving force increase control provides an effect of suppressing a single knock as described below. In general, when starting from an idling state where the accelerator is depressed relatively strongly, the vehicle is in a low speed and high load state, which is a condition in which a single knock is likely to occur. On the other hand, in the start driving force increase control, it is possible to suppress the occurrence of one knock by increasing the engine speed Ne at the time point t1, that is, by increasing the speed. This effect becomes more prominent as the idle rotation speed decreases.

  In addition, another factor that makes one-shot knocking easily occurs is a phenomenon that the intake air temperature rises. According to the start driving force increase control, the engine rotational speed Ne is increased at time t1, that is, the intake air flow rate. By increasing this, the time during which intake air stays in the high-temperature engine room can be shortened. That is, the intake air temperature can be reduced in advance. Accordingly, an increase in the combustion temperature when the accelerator is turned on at a subsequent time point t2 is suppressed, and it is possible to make one knocking difficult to occur.

  Thus, since one knock is suppressed, the retard amount of the ignition retard for suppressing one knock can be reduced. Accordingly, a decrease in engine torque due to ignition retard can be suppressed, and the startability can be further improved.

  Subsequently, at time t3 after time t2, the alternator power generation amount Alt is gradually returned to normal control. The time point t3 is preferably 3 to 5 seconds after the time point t2, for example. Thereafter, the control shifts to normal traveling control.

  FIG. 3 is a time chart when the driver does not depress the accelerator after the first time point (time points t1 and t1 ′). The horizontal axis and each vertical axis are in accordance with FIG.

  When the brake is released at time t1 (characteristic 211), the throttle opening K is increased from 0% to K1% (characteristic 191), and the engine speed Ne increases from N1 to N2 (characteristic 161). At t1 ′, the target power generation amount (target output current value) of the alternator 28 is increased to the first target value Ib (A) (characteristic 171), and the electric supercharger 26 is driven at the rotational speed N6 (characteristic 181). Is the same as in FIG.

  However, the accelerator opening degree Ac remains 0% (characteristic 201). In other words, the driver has released the brake, but has not performed the accelerator operation at least immediately. This is, for example, a driving mode seen in creep running during traffic jams.

  In such a case, in this embodiment, the start driving force increase control is interrupted at time t9. The time point t9 is preferably 2 to 5 seconds after the time point t1, for example. At time t9, the throttle opening K is returned to 0%, and the engine speed Ne is also returned to the normal idle speed N1. Further, the alternator power generation amount Alt is returned to the original power generation amount Ia (A), and the driving of the electric supercharger 26 is also stopped. (Characteristic 181).

  By doing so, it is possible to prevent deterioration in fuel consumption caused by continuously increasing the engine output for a long time. At this time, as indicated by the characteristics 191, the characteristics 171, and the characteristics 181, the throttle opening K, the alternator power generation amount Alt, and the electric supercharger rotation speed Ns are gradually returned. By doing so, the uncomfortable feeling given to the driver can be suppressed.

  In addition, it is assumed that the accelerator is depressed with a large degree of acceleration request after time t9. In this case, the normal intake air flow rate, the normal idle rotation speed, and the acceleration from the stopped state of the electric supercharger 26 are obtained. However, in this case, the acceleration is after creeping for a while and has already reached a certain speed. Therefore, the stall rotation speed (rotation speed in a state where slippage with the automatic transmission 50 side is suppressed) is higher than that in the start from the stop state. That is, the engine rotation speed at the initial acceleration is likely to increase, which is advantageous for increasing the output torque and suppressing one-shot knocking, so there is little concern about the startability. This is because the automatic transmission 50 is of any type, such as a multi-stage transmission, a continuously variable transmission, or a clutchless automatic transmission called an autoshift manual, and a torque converter or This applies to any mechanism such as an electromagnetic clutch.

  Although not specifically illustrated, at the time t2 shown in FIG. 2, although the accelerator is depressed, the start driving force increase control is interrupted even when the accelerator opening change rate DA is small, that is, when the acceleration request degree is small. As shown in FIG. 3, the throttle opening K, the alternator power generation amount Alt, and the electric supercharger rotational speed Ns are gradually returned to normal control. By doing so, it is possible to prevent the acceleration that is higher than the driver's request from being caused and the user from feeling uncomfortable.

  4 to 5 are schematic flowcharts centering on the starting driving force increase control of this embodiment. When the flowchart starts, the flag F is first determined in step S10. The flag F is a flag indicating an execution state of the start driving force increase control. When the flag F = 0 (reset state), the start driving force increase control is not being executed, and when the flag F = 1, the start driving force increase control is being executed.

  Immediately after the start of the flowchart (when the start driving force increase control is not executed), the flag F is in a reset state, that is, the flag F = 0, and therefore, NO is determined in step S10. Next, in step S12, it is determined whether or not the engine is idling (engine speed Ne = N1, accelerator opening degree Ac = 0%). If YES is determined in step S12, it is then determined whether or not the brake is released from ON to OFF (step S14).

  If it is determined NO in step S12 or step S14, the execution condition of the starting driving force increase control is not satisfied, and the process returns. If it is determined as YES in step S14, the execution condition of the start driving force increase control is established, and the process proceeds to start drive force increase control.

  When the starting driving force increase control is started (time t1), the timer TA is first reset, and the elapsed time from the time t1 is measured (step S16).

  Next, the throttle opening degree controller 2b increases the throttle opening degree K from 0% to K1% (step S18).

  At time t1 ′ (YES in step S20) when timer TA> predetermined period m1 (eg, m1 = 0.1 s), the target power generation amount (output current value) of alternator 28 is set to normal value Ia (eg, Ia = 30 A). To a first target value Ib (for example, Ib = 65A) (step S22).

  Next, 1 is input to the flag F (step S24), and the electric supercharger 26 is driven at the rotational speed N6 (the rotational speed corresponding to the power consumption (Ib-Ia)) (step S30).

  Next, it is determined whether or not the accelerator is turned on (step S34). If NO, it is further determined whether or not timer TA> predetermined period m2 (for example, m2 = 2 to 5s) (step S46). If NO in step S46, the process returns. Since the flag F = 1 at this time, it is determined YES in step S10 in the next routine, and the process proceeds to step S34. Thus, a standby state is repeated in which the routine from step S34 to step S46 is repeated.

  During the standby state, if YES in step S34, that is, if it is determined that the accelerator is on (time t2), the acceleration request degree determination unit 2g determines whether or not the accelerator opening change rate DA> predetermined value a1. Step S36).

  If YES in step S36, it is determined that the acceleration request degree is large. The target power generation amount of the alternator 28 is set to the second target value Ic (for example, Ic = 0 to 30A) according to the accelerator opening change rate DA. To do. The second target value Ic is set to a smaller value as the accelerator opening change rate DA is larger, and the reduction margin from the first target value Ib is increased (step S42).

  When a predetermined period m3 (eg, m3 = 3 to 5 s) has elapsed since the accelerator was turned on (time t2) (YES in step S44), the alternator 28 is gradually returned to normal control (step S50), and the flag F is reset. (Step S52) The starting driving force increase control is terminated. Thereafter, the routine returns to normal alternator control (step S54), normal throttle opening control (step S56), and normal electric supercharger control (step S60).

  When it is determined NO in step S36, it is determined that the accelerator is turned on but the degree of acceleration request is small, and the start driving force increase control is interrupted. That is, the throttle opening K is gradually returned to the normal control (step S48), and the process proceeds to step S50.

  If it is determined YES in step S46, it means that the accelerator is not turned on even after a predetermined period m2 after the brake is released at time t1. Also in this case, the start driving force increase control is interrupted and the process proceeds to step S48.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to said Embodiment, A various deformation | transformation is possible within the range of the invention described in the claim. For example, the target engine is not limited to a spark ignition engine, and may be one that performs combustion by compression self-ignition, such as a diesel engine. In that case, it is not always necessary to increase or decrease the intake flow rate.

  In the above embodiment, the brake switch 35 for detecting on / off of the brake is provided for both the foot brake and the side brake as the brake operation detecting means. However, the displacement of the brake pedal is detected linearly only by the foot brake. A position sensor (not shown) is provided, and the brake switch 35 of the side brake and this position sensor detect that all brakes have been released, and the brake pedal operating speed (brake pedal per hour) when the brake is released The ratio of the displacement amount may be detected.

  By detecting the operation speed of the brake pedal in this way, when the brake release is operated gently, the increase in the throttle opening K based on the brake release is suppressed, and further the increase in the target power generation amount of the alternator 28 is suppressed. In addition, by prohibiting the driving of the electric supercharger 26 or setting it to a weak driving force state, the intake air amount for acceleration is increased in a state where there is almost no sudden acceleration request even though the brake is released. Therefore, the driving of the electric supercharger 26 and the load increase of the alternator 28 are suppressed, and fuel consumption can be reduced.

  In addition, since the automatic transmission 50 is connected to the engine body 1, when the brake release is gently operated, the increase in the engine speed is suppressed, and extremely low speed creep travel can be secured.

  Furthermore, as a configuration of the supercharger, the electric supercharger 26 may not be used alone. For example, it may be used in combination with a so-called turbocharger or mechanical supercharger.

  The first target value Ib and the second target value Ic of the alternator power generation amount at the time point t1 ′ (first time point) and the time point t2 (second time point) are not limited to the above values, but within a range of Ib> Ic. Any setting may be made. Further, the target value N2 of the engine speed Ne after the time point t1 is not limited to the above value. However, N2 is preferably about 1000 rpm or less so as not to give the driver a sense of incongruity.

  In the above embodiment, the start driving force increase control is interrupted when the acceleration request level at the time point t2 is small. You may do it.

1 is a schematic block diagram including an automobile engine control device according to an embodiment of the present invention. It is a time chart which shows the state at the time of a vehicle starting from an idle driving state. It is a time chart when the accelerator is not depressed within a predetermined time after the brake is released. It is a front | former stage of the general | schematic flowchart centering on start driving force increase control concerning the said embodiment. It is the latter part of the flowchart.

Explanation of symbols

2 ECU
2a Electric supercharger control unit (electric supercharger control means)
2b Throttle opening control unit (intake flow rate adjusting means)
2e Alternator power generation amount control unit (target current control means)
2g Acceleration request degree determination unit (acceleration request degree determination means)
23 Throttle valve (intake flow rate adjustment means)
26 Electric supercharger 28 Alternator 30 Crank angle sensor (rotational speed detection means)
34 Accelerator opening sensor (accelerator operation detection means)
35 Brake switch (brake operation detection means)
50 Automatic transmission 55 Battery Ib First target value Ic (of alternator target output current value) Second target value (of alternator target output current value) t1, t1 ′ Time point t1, t1 ′ (first time point)
t2 time point t2 (second time point)

Claims (8)

An electric supercharger that is electrically driven to supercharge intake air;
Electric supercharger control means for controlling the driving of the electric supercharger;
An alternator driven by engine power;
A target current control means for adjusting a target output current value of the alternator,
In an automobile engine control device mounted on a vehicle together with an automatic transmission,
A rotational speed detecting means for detecting the rotational speed of the engine;
Brake operation detection means for detecting the brake operation state of the vehicle;
An accelerator operation detecting means for detecting an accelerator operation state of the vehicle,
At a first time when the engine is operating at a predetermined idle rotation speed and the accelerator is off and the brake is off, the electric supercharger control means drives the electric supercharger to output the engine. Rutotomoni increased, the target current control means increases the target output current value of the alternator to the first target value to increase the engine load so as to cancel the engine output increases, then, the was the accelerator-on At two time points, the target current control means forcibly reduces the target output current value of the alternator to the second target value while preventing the increased engine output from being reduced, thereby reducing the engine load. An automotive engine control device that performs start driving force increase control for obtaining driving force.   The automotive engine control apparatus according to claim 1, wherein the first target value is set to a constant value equal to or greater than a current consumption of the electric supercharger. Intake flow rate adjustment means to adjust the intake flow rate,
3. The automobile engine control device according to claim 1, wherein the intake air flow rate adjusting means increases the intake air flow rate at the first time point and controls to increase the engine rotation speed. 4.   4. The automobile engine control apparatus according to claim 1, wherein the second target value is a predetermined constant value. 5. Acceleration request degree determination means for determining the acceleration request degree of the vehicle from the accelerator operation state,
4. The automobile engine control apparatus according to claim 1, wherein the second target value is set to a smaller value as the degree of acceleration request at the second time point is larger. 5. The said 2nd target value is made into a value smaller than the average consumption current of the vehicle at the time of driving | running | working in a light extinction state at least on predetermined conditions. The engine control apparatus for automobiles as described.   When the accelerator is not turned on even after a predetermined time has elapsed from the first time point, the electric supercharger control means gradually reduces the rotational speed of the electric supercharger, and the target current control means The automotive engine control apparatus according to any one of claims 1 to 6, wherein the target output current value of the alternator is gradually reduced from the first target value.   The speed of the brake off operation at the first time point is detected by the brake operation detecting means, and when the speed of the brake off operation is relatively slow, the electric supercharger control means 4. The driving of the electric supercharger is prohibited or made into a weak driving force state, and an increase in the target output current value of the alternator by the target current control means is suppressed. The automobile engine control device according to claim 1.

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