JP5811033B2 - Engine control device - Google Patents

Description

  The present invention automatically stops an engine (internal combustion engine) provided with a supercharger with a waste gate valve that is closed using negative pressure when the idling stop condition is satisfied, and when the restart condition is satisfied, The present invention relates to a control device that automatically restarts an engine.

  For example, Patent Document 1 discloses that, in an engine having a variable displacement supercharger in which the turbine side has a variable capacity by a variable nozzle vane mechanism, when the idling stop execution condition is satisfied and the engine is stopped, the variable nozzle vane mechanism It is described that the operating state of the variable nozzle vane mechanism (the nozzle vane opening degree is small) is maintained by maintaining the negative pressure in the negative pressure actuator that is the operating source.

  In the variable nozzle vane mechanism, a plurality of nozzle vanes are arranged on the outer peripheral side of the turbine wheel at equal intervals in the circumferential direction, and these nozzle vanes are rotated in synchronization with each other (opening / closing operation), thereby opposing each other of the adjacent nozzle vanes. By changing the interval (nozzle vane opening), that is, the flow passage area (throat area) between the nozzle vanes, the flow rate of the exhaust gas introduced toward the turbine wheel can be adjusted.

  For example, a variable capacity supercharger equipped with the variable nozzle vane mechanism can increase the flow rate of exhaust gas when the flow passage area is reduced at a low engine rotation speed. It becomes possible to obtain pressure.

  A vacuum pump driven by an engine is used as a negative pressure source for supplying a negative pressure to the negative pressure actuator. A negative pressure cutoff valve is provided between the vacuum pump and the negative pressure actuator.

  In addition to this, for example, Patent Document 2 states, “In the configuration where the intake manifold is a negative pressure source for bringing the negative pressure chamber of the brake booster into a negative pressure state, the condition for stopping fuel injection to the engine for eco-run control is disclosed. The negative pressure of the brake booster exceeds a predetermined threshold value.

  Further, for example, Patent Document 3 describes that “when the brake booster negative pressure becomes lower than a predetermined value while the engine is stopped, the vacuum pump is driven to increase the brake booster negative pressure to a predetermined value or higher”.

JP 2012-7544 A JP 2011-64188 A Japanese Utility Model Publication No.59-91445

  In the above-mentioned Patent Document 1, the negative pressure cutoff valve installed between the negative pressure pump and the negative pressure actuator is closed between the engine stop and start, and the idling stop execution condition is established. It is described that when the engine is stopped, the operating state of the variable nozzle vane mechanism of the turbocharger (small nozzle vane opening degree) is maintained, so that a high supercharging effect can be obtained when the engine is restarted I can say.

  However, since the supercharger described in Patent Document 1 is a type that is not equipped with a waste gate valve, the configuration that is a premise of the invention is different from the present invention. Therefore, as a matter of course, Patent Document 1 does not include a description regarding the control of the waste gate valve when the engine is restarted from the idling stop.

  In Patent Document 2, a negative pressure supply source of a brake booster is used as an intake manifold, and a vacuum pump driven by an engine is not used.

  Since the above-mentioned Patent Document 3 does not describe a drive source for the vacuum pump, it is unclear how to drive the vacuum pump when the vacuum pump is driven while the engine is stopped.

  In view of such circumstances, the present invention automatically stops an engine provided with a supercharger with a waste gate valve that is closed using negative pressure when an idling stop condition is satisfied, In a control device that automatically restarts the engine when it is established, it is predicted that a negative pressure is required to close the wastegate valve when the idling stop condition is satisfied when the engine is restarted later. In this case, it is an object of the present invention to make it possible to give priority to securing a negative pressure necessary for closing the waste gate valve by tightening the idling stop execution permission condition.

  The present invention automatically stops an engine provided with a supercharger with a waste gate valve that is closed using negative pressure when the idling stop condition is satisfied, and automatically activates the engine when the restart condition is satisfied. A negative pressure source for generating a negative pressure for closing the waste gate valve is a vacuum pump driven by the engine, and when the idling stop condition is satisfied, A determination unit that permits the idling stop to be executed on condition that the negative pressure of the negative pressure source is equal to or greater than a predetermined threshold value, and for closing the waste gate valve at a subsequent restart prior to the determination by the determination unit If it is predicted that negative pressure will be required, set the threshold value higher than if it is predicted not to be required And a tough, it is characterized in that.

  Since it is assumed that the vacuum pump is stopped when the engine is stopped, when the idling stop is executed, the driving of the vacuum pump is stopped.

  "Negative pressure" used in this specification is used as the magnitude (absolute value) of negative pressure with reference to atmospheric pressure, and is expressed as being closer to vacuum and smaller as it is closer to atmospheric pressure. It expresses.

  Furthermore, when the waste gate valve is closed, it is possible to quickly increase the supercharging pressure of the turbocharger in response to a request for increasing the engine speed, thereby improving the engine response (response of the engine rotation to the acceleration request). To come. From this, it can be rephrased that “necessary a negative pressure for closing the waste gate valve” is “necessary to improve engine response”.

  In consideration of this point, in the present invention, when the idling stop condition is satisfied, the negative pressure for closing the waste gate valve at the time of subsequent engine restart is determined when determining whether or not the execution is permitted. If it is predicted that it will be necessary, the threshold for use in determining the idling stop execution permission condition is set high, thereby making the idling stop execution permission criteria stricter. .

  In this configuration, prior to the execution of idling stop, when it is predicted that a negative pressure for closing the waste gate valve is required when the engine is restarted later, and when the negative pressure cannot be secured, A negative pressure required for closing the waste gate valve can be secured by driving a vacuum pump by the engine without permitting execution of the idling stop.

  On the other hand, if it is predicted that a negative pressure for closing the waste gate valve is required at the time of a subsequent engine restart before the idling stop is executed and the negative pressure can be secured, the idling is performed. It is possible to reliably close the waste gate valve at the time of a subsequent restart while permitting the execution of the stop to improve fuel efficiency.

  Preferably, the vacuum pump is configured to be used as a negative pressure source for introducing negative pressure to both an actuator for opening and closing the waste gate valve and a brake booster of a braking device of a vehicle, The determination unit may be configured to permit the idling stop to be executed on condition that a residual negative pressure of the brake booster is equal to or greater than a predetermined threshold.

  In this configuration, the vacuum pump is used not only as a negative pressure source of the negative pressure actuator for driving the waste gate valve but also as a negative pressure source of the brake booster.

  Here, for example, if the driver repeatedly performs a braking operation (braking operation) while the engine is stopped, the residual negative pressure of the brake booster decreases. In such a situation, the engine is restarted later. As a result, even if the vacuum pump is driven, it is expected that it takes time to bring the negative pressure chamber of the brake booster to a predetermined negative pressure. Therefore, in such a situation, it takes a long time to secure the negative pressure necessary to close the waste gate valve from the time when the vacuum pump is started, that is, from the time when the engine is restarted. There is a concern that sometimes the waste gate valve cannot be closed quickly.

  The inventor of the present application pays attention to this point and determines whether or not the idling stop execution permission condition is satisfied by examining whether or not the residual negative pressure of the brake booster is equal to or greater than a predetermined threshold value. I came up with the idea that this would be possible.

  Preferably, the setting unit needs to close the waste gate valve when a power mode for increasing a response (engine response) of engine rotation to an acceleration request at a time of stopping is higher than usual. The configuration can be predicted.

  Here, a specific example for determining whether or not it is necessary to close the waste gate valve to improve the engine response when the engine is restarted from the idling stop is specified. If the engine response is poor even when the engine is restarted after starting idling when the vehicle is temporarily stopped and the engine is restarted, the driver may feel uncomfortable. With this setting, the engine response is improved, so that the driver does not feel uncomfortable.

  Preferably, the setting unit needs to close the waste gate valve when an operation direction of the direction indicator coincides with a steering angle direction of the steering wheel when the direction indicator of the vehicle is operated when the vehicle is stopped. It can be set as the structure which estimates that there exists.

  Here, a specific example for determining whether or not it is necessary to close the waste gate valve to improve the engine response when the engine is restarted from the idling stop is specified. If the engine response is poor when the engine is restarted after starting idling when the vehicle is temporarily stopped and then starting to turn right or left, there is a risk of giving the driver a sense of incongruity. Since the engine response is improved, the driver does not feel uncomfortable.

  Preferably, the control device may further include an execution unit that executes the idling stop when it is determined that the determination unit permits.

  Here, the function realizing elements of the control device according to the present invention are further specified.

  The present invention automatically stops an engine provided with a supercharger with a waste gate valve that is closed using negative pressure when the idling stop condition is satisfied, and automatically activates the engine when the restart condition is satisfied. When the idling stop condition is satisfied in the control device to be restarted, if it is predicted that a negative pressure is required to close the waste gate valve at a later restart, the idling stop is executed. By tightening the permission conditions, priority can be given to securing a negative pressure necessary for closing the waste gate valve.

It is a figure which shows schematic structure of one Embodiment of the engine used as the application object of the control apparatus which concerns on this invention, and its periphery. FIG. 2 is a diagram illustrating a schematic configuration and an input / output system of the control device in FIG. 1. It is a graph used for description of the execution permission conditions of the eco-run control by the control apparatus of FIG. It is a flowchart which shows the control procedure of the eco-run control by the control apparatus of FIG.

  BEST MODE FOR CARRYING OUT THE INVENTION Best modes for carrying out the present invention will be described in detail below with reference to the accompanying drawings.

  1 to 4 show an embodiment of the present invention. The engine 1 exemplified in this embodiment has, for example, in-line four cylinders, but the number of cylinders and the engine type are not particularly limited.

  A cylinder head (not shown) of the engine 1 is provided with an intake manifold 2 for distributing and supplying intake air to each cylinder, and an exhaust manifold 3 for collecting exhaust gas discharged from each cylinder. ing.

  An intake pipe 4 for taking in air from the atmosphere is connected to the intake manifold 2. An air cleaner 5 is attached to the inlet of the intake pipe 4. The intake manifold 2 and the intake pipe 4 constitute an intake passage.

  A throttle valve 6 for adjusting the intake air amount of the engine 1 is provided upstream of the intake manifold 2 in the intake flow direction. The throttle valve 6 is of an electronic control type that is operated by controlling the throttle motor 6 a by the control device 100.

  The exhaust manifold 3 is connected to the exhaust ports of the cylinders of the engine 1 on the upstream side, and is integrated into a single shape on the downstream side.

  A downstream end of the exhaust manifold 3 is connected in communication with a turbine housing 24 of a supercharger 20 called a turbocharger.

  The supercharger 20 supercharges intake air using exhaust pressure and supplies it to the engine 1, and includes a turbine wheel 21, a compressor impeller 22, and the like.

  The turbine wheel 21 is rotatably provided in the turbine housing 24. The compressor impeller 22 is provided in a compressor housing 25 installed in the middle of the intake pipe 4. The compressor impeller 22 is attached to a turbine shaft 23 that is integral with the turbine wheel 21. Thereby, the turbine wheel 21 and the compressor impeller 22 rotate integrally.

  An exhaust pipe 9 for discharging exhaust gas to the atmosphere is connected to the downstream side of the turbine housing 24. The exhaust pipe 9 is provided with a catalyst 10 for purifying exhaust gas. The exhaust manifold 3 and the exhaust pipe 9 constitute a part of the exhaust passage.

  As a basic operation of the supercharger 20, the turbine wheel 21 is rotated by exhaust energy discharged from the engine 1 to the exhaust manifold 3, and the compressor impeller 22 is rotated integrally therewith, whereby the intake pipe 4. Is supercharged and forcedly fed into the combustion chamber of each cylinder of the engine 1. The air supercharged by the compressor impeller 22 is cooled by the intercooler 7. The intercooler 7 is installed downstream of the compressor impeller 22 in the intake pipe 4 in the intake air flow direction.

  The supercharger 20 of this embodiment is provided with a waste gate valve (WGV) 31.

  The waste gate valve 31 adjusts the amount of exhaust gas blown to the turbine wheel 21 by diverting a part of the exhaust gas from the engine 1. For example, when the flow rate of the exhaust gas blown to the turbine wheel 21 is excessively increased, the excessive increase in the rotation of the turbine wheel 21 can be suppressed by opening the waste gate valve 31.

  The turbine housing 24 is provided with a bypass passage 27 for guiding exhaust gas discharged from the engine 1 to the catalyst 10 by bypassing the turbine wheel 21.

  The bypass passage 27 is installed so as to short-circuit the inlet side and the outlet side of the turbine housing 24. An exhaust port of the bypass passage 27 is provided next to an exhaust gas exhaust port 26 that rotates the turbine wheel 21 in the turbine housing 24.

  The waste gate valve 31 is installed on the discharge port side of the bypass passage 27 so as to be openable and closable, and adjusts the opening amount of the bypass passage 27 to adjust the exhaust gas bypass amount. By adjusting the exhaust gas bypass amount, for example, the supercharging pressure can be controlled, and for example, control can be performed so that the catalyst 10 can be activated quickly after the engine 1 is cold started. It becomes possible.

  As a driving device for driving the waste gate valve 31, for example, a vacuum pump 32, an actuator 33, a pressure accumulating tank 34, a vacuum switching valve (VSV) 35, a check valve 36, and the like are provided.

  The vacuum pump 32 generates negative pressure when driven by the engine 1. Although not shown in detail, for example, the drive shaft of the vacuum pump 32 is driven when the rotational power of the crankshaft of the engine 1 is input via a power transmission unit such as an auxiliary belt and a pulley. ing.

  That is, the vacuum pump 32 is driven when the engine 1 is driven, and is stopped when the engine 1 is stopped. For this reason, the vacuum pump 32 also stops the generation of negative pressure when the engine 1 is stopped.

  The actuator 33 opens and closes the waste gate valve 31 using the negative pressure generated by the vacuum pump 32 as an operating source. The pressure accumulation tank 34 accumulates negative pressure generated by the vacuum pump 32. The VSV 35 adjusts the amount of supply (introduction) of the negative pressure generated by the vacuum pump 32 and accumulated in the pressure accumulation tank 34 to the actuator 33. The check valve 36 prevents the negative pressure in the pressure accumulating tank 34 from leaking to the vacuum pump 32 side.

  The operation of the VSV 35 will be described. First, when the electromagnetic solenoid of the VSV 35 is in a non-excited state, the inside of the cylinder 33a is brought to atmospheric pressure by opening the cylinder 33a of the actuator 33 to the atmosphere. In this case, the rod 33c of the actuator 33 is pushed most out of the cylinder 33a by the urging force of a reverse spring (not shown), so that the waste gate valve 31 is opened.

  On the other hand, when the electromagnetic solenoid of the VSV 35 is in an excited state, the inside of the cylinder 33a of the actuator 33 is set to a negative pressure by bringing the vacuum pump 32 and the actuator 33 into communication. In this case, since the rod 33c of the actuator 33 is pulled into the cylinder 33a against the urging force of the reverse spring, the waste gate valve 31 is closed. When the waste gate valve 31 is closed in this way, the flow rate of the exhaust gas to the turbine wheel 21 can be increased, and the supercharging pressure of the supercharger 20 can be quickly increased.

  Thus, when a predetermined negative pressure is introduced into the cylinder 33a of the actuator 33, the waste gate valve 31 is closed by pulling the rod 33c connected to the diaphragm 33b in the cylinder 33a. When the pressure inside the cylinder 33a is set to atmospheric pressure, the waste gate valve 31 is opened by pushing the rod 33c by the urging force of a reverse spring (not shown).

  In this embodiment, the above-described vacuum pump 32 is configured to be used as a negative pressure source of the brake booster 42 of the braking device 40 provided in the vehicle.

  The braking device 40 includes a brake pedal 41, a brake booster 42, a master cylinder 43, a check valve 44, and the like.

  The brake pedal 41 is a pedal that is depressed by the driver to brake the vehicle, and is connected to the input rod 45 of the brake booster 42.

  The brake booster 42 is a device that generates an assist force proportional to the pedaling force applied to the brake pedal 41. Although not shown, a negative pressure chamber is provided on the master cylinder 43 side. An output rod (not shown) of the brake booster 42 is connected to an input shaft (not shown) of the master cylinder 43.

  The master cylinder 43 generates hydraulic pressure according to the depression force of the brake pedal 41 and the assist force from the brake booster 42. Although not shown, the master cylinder 43 is connected to a wheel cylinder provided in a caliper of a disc brake of each wheel via a hydraulic circuit. Each wheel cylinder generates a braking force by pressing the brake pad against the disc brake by the hydraulic pressure supplied from the master cylinder 43.

  The negative pressure chamber of the brake booster 42 is connected to a negative pressure passage 37 that connects the vacuum pump 32 and the pressure accumulation tank 34 via a negative pressure passage 46.

  A check valve 44 is provided at a connection portion between the negative pressure passage 46 and the negative pressure chamber of the brake booster 42. The check valve 44 opens when the negative pressure (absolute value) of the negative pressure passage 37 (accumulation tank 34) is larger than the negative pressure (absolute value) of the negative pressure chamber of the brake booster 42. As a result, negative pressure is accumulated in the negative pressure chamber of the brake booster 42.

  A pressure sensor 51 is provided in the negative pressure passage 46 connecting the vacuum pump 32 and the brake booster 42. The pressure sensor 51 inputs a signal corresponding to the residual negative pressure of the brake booster 42 to the control device 100.

  This pressure sensor 51 can use an existing one. This is because, in the conventional configuration in which the negative pressure in the intake manifold is used as the negative pressure source of the brake booster 42, generally, the negative pressure chamber of the brake booster 42 is detected in order to detect the residual negative pressure of the brake booster 42. A pressure sensor is installed at the inlet. This pressure sensor can be used as the pressure sensor 51. Therefore, it can be said that it is advantageous in suppressing an unnecessary increase in equipment cost.

  As shown in FIG. 2, the control device 100 is a generally known electronic control unit (ECU), and includes a CPU 101, a ROM 102, a RAM 103, a backup RAM 104, and the like.

  The ROM 102 stores at least a control program for controlling various operations of the engine 1 and a control program related to eco-run control described below. The CPU 101 executes arithmetic processing based on the program and map stored in the ROM 102. A RAM 103 is a memory that temporarily stores calculation results of the CPU 101, data input from each sensor, and the like. The backup RAM 104 is a non-volatile memory that stores data to be saved when the engine 1 is stopped.

  The CPU 101, ROM 102, RAM 103, and backup RAM 104 are connected to each other via a bus 107, and are connected to an input interface 105 and an output interface 106.

  The input interface 105 is connected to at least an accelerator opening sensor 61, a throttle opening sensor 62, a crank position sensor 63, a wheel speed sensor 64, a brake switch 65, a pressure sensor 51, and the like. At least the fuel injection valve 11, the throttle motor 6a, the VSV 35, and the like are connected to the output interface 106.

  The control device 100 detects the depression amount of an accelerator pedal (not shown) based on the signal input from the accelerator opening sensor 61 and detects the opening of the throttle valve 6 based on the signal input from the throttle opening sensor 62. Then, the rotational speed of the engine 1 is detected based on the signal input from the crank position sensor 63, and the rotational speed of the wheel and the traveling speed (vehicle speed) of the vehicle (not shown) are determined based on the signal input from the wheel speed sensor 64. Based on the ON signal from the brake switch 65, it is detected that the brake pedal 41 has been depressed more than a predetermined amount.

  In this embodiment, a power switch 66 for selecting either the normal mode or the power mode (or sports mode) is provided. “Normal mode” is selected when the power switch 66 is off, and “power mode” is selected when the power switch 66 is on.

  The power mode is a mode in which a response (response) of engine rotation to a vehicle acceleration request (for example, accelerator pedal operation) is made higher than normal (normal mode). The normal mode is a mode in which improvement in fuel efficiency is prioritized over improvement in engine response.

-Eco-run control-
The eco-run control means that the engine 1 is automatically stopped when the idling stop condition is satisfied while the vehicle is temporarily stopped, such as waiting for a signal at an intersection, and the restart condition is satisfied during the idling stop. This is control that automatically restarts the engine 1.

  The idling stop conditions are (1) the ignition is ON, (2) the vehicle speed is zero (detected based on the input of the output signal from the wheel speed sensor 64), and (3) the accelerator pedal (not shown) ) Is depressed (detected based on the output signal input from the accelerator opening sensor 61), (4) the brake pedal 41 is depressed (ON signal input from the brake switch 65) Based on the detection). It is assumed that the idling stop condition is satisfied when all these four conditions are satisfied.

  The restart conditions are as follows: (1) the brake pedal 41 is depressed and released (detected based on the input of an off signal from the brake switch 65), and (2) the accelerator pedal (not shown) is depressed. (Detected based on the input of the output signal from the accelerator opening sensor 61). Assume that the engine restart condition is satisfied when both of these two conditions are satisfied.

  Specifically, the control device 100 temporarily executes the engine 1 by executing a process (fuel cut) for stopping the fuel injection operation of the fuel injection valve 11 (shown only in FIG. 2) when executing the idling stop. While stopping, the VSV 35 is closed.

  When the engine 1 is idling stopped in this way, the driving of the vacuum pump 32 is stopped, but the pressure accumulation tank is constituted by the check valve 36 and the VSV 35 closed between the pressure accumulation tank 34 and the vacuum pump 32. 34 is sealed. Thereby, even after the drive of the vacuum pump 32 is stopped, the negative pressure in the pressure accumulation tank 34 and the negative pressure in the cylinder 33a of the actuator 33 are maintained. Therefore, since the rod 33c of the actuator 33 remains pulled into the cylinder 33a, the waste gate valve 31 is maintained in the closed state. Further, since the check valve 44 is provided at the connection portion between the negative pressure chamber of the brake booster 42 and the negative pressure passage 46, the negative pressure in the negative pressure chamber is also maintained.

  When the restart condition is satisfied during idling stop, the control device 100 starts the fuel injection operation by the fuel injection valve 11 and simultaneously operates the starter motor (not shown) to crank the engine 1. Then, the engine 1 is started.

  When the engine 1 is started, the vacuum pump 32 is driven as the crankshaft (not shown) rotates, so that negative pressure is supplied to the negative pressure chambers of the pressure accumulation tank 34 and the brake booster 42, respectively.

  When the engine 1 is restarted, the VSV 35 is opened to supply the negative pressure accumulated in the pressure accumulation tank 34 to the cylinder 33a of the actuator 33.

  By the way, in this embodiment, when the idling stop condition is satisfied, execution of the idling stop is permitted on condition that the residual negative pressure of the brake booster 42 is equal to or greater than a predetermined threshold. The threshold value is appropriately set based on the residual negative pressure of the brake booster 42 that makes it possible to ensure the braking force necessary for stopping the vehicle.

  In addition, with respect to the threshold value, when it is predicted that a negative pressure for closing the waste gate valve 31 is required at the time of restart from the idling stop, in other words, it is predicted that the engine response needs to be improved. In this case, it is set higher than the case where it is predicted that it is not necessary (normal case).

  The reason for changing the threshold in this way will be described.

  As in this embodiment, when it is assumed that the vacuum pump 32 is used as a negative pressure source for both the WGV driving actuator 33 and the brake booster 42 as the engine 1 is driven, the pressure accumulating tank 34 to be used is used. The larger the capacity, the less influenced by the brake booster 42 side.

  However, when the mounting space of the accumulator tank 34 is restricted in the vehicle, the accumulator tank 34 having a sufficient capacity as described above cannot be used. Therefore, when the pressure accumulation tank 34 having a small capacity is used due to the restriction, the waste gate valve 31 is closed with a negative pressure obtained by adding the residual negative pressure of the brake booster 42 to the negative pressure accumulated in the pressure accumulation tank 34. It must be designed to ensure the necessary negative pressure.

  Here, as described above, when the engine 1 is stopped by executing the idling stop, the negative pressure accumulated in the pressure accumulation tank 34 is maintained. When the brake operation is repeatedly performed by the driver, the residual negative pressure of the brake booster 42 becomes small.

  In such a situation, even if the VSV 35 is opened later when the engine 1 is restarted, there is a high possibility that the negative pressure necessary for closing the waste gate valve 31 cannot be quickly secured. There is a concern that it takes time until the valve 31 is completely closed. The cause is that although the vacuum pump 32 is driven as the engine 1 is restarted, it takes some time for the negative pressure chamber of the brake booster 42 to reach a predetermined negative pressure due to an operation time lag of the vacuum pump 32. This is because of this.

  This point will be described with reference to FIG.

  In FIG. 3, the vertical axis represents the time from the start of driving of the vacuum pump 32 until the internal pressure of the actuator 33 reaches the negative pressure required to close the waste gate valve 31 (the arrival time), and the horizontal axis represents the accumulated pressure. This is the capacity of the tank 34.

  In FIG. 3, the alternate long and short dash line indicates the target arrival time, and the thick solid line indicates a normal allowable limit line for allowing the execution of the eco-run control determined based on the residual negative pressure of the brake booster 42. Yes. It is divided into an execution prohibition area and an execution allowable area with this allowable limit line as a boundary. The two-dot chain line indicates an allowable limit line that is suitable when engine response improvement is required at the time of restart from the idling stop.

  First, for example, when the capacity of the pressure accumulating tank 34 can be made larger than “Va” in FIG. 3, the arrival time is the target arrival time regardless of the residual negative pressure of the brake booster 42 (FIG. 3 Pmin to Pmax). It becomes the following.

  If such an accumulator tank 34 can be used, even if the idling stop condition of the eco-run control is satisfied, even if the residual negative pressure of the brake booster 42 is Pmin in FIG. 3, for example, atmospheric pressure, the accumulator tank 34, the internal pressure of the actuator 33 can be quickly reached to the negative pressure required for closing the waste gate valve 31 only by the negative pressure accumulated in the engine 34. It can be said that the engine response can be improved immediately upon restart. Therefore, in this case, it can be said that there is no problem even if the determination threshold value of the residual negative pressure of the brake booster 42 is set to Pmin in FIG. Therefore, in this case, the determination threshold value may be appropriately set based on the residual negative pressure of the brake booster 42 that makes it possible to ensure the braking force necessary for stopping the vehicle as described above.

  However, when the capacity of the pressure accumulating tank 34 has to be made smaller than “Va” in FIG. 3 due to the mounting restrictions, the arrival time reaches the target as the residual negative pressure of the brake booster 42 decreases. It will be over time.

  For example, when the capacity of the pressure accumulating tank 34 is set to “Vb” which is smaller than “Va” in FIG. 3, the arrival time becomes the target time when the residual negative pressure of the brake booster 42 becomes smaller than the predetermined value Px in FIG. If the remaining negative pressure of the brake booster 42 is equal to or greater than the predetermined value Px in FIG. 3, the arrival time is less than the target arrival time.

  Therefore, in this case, if the residual negative pressure of the brake booster 42 is smaller than the predetermined value Px in FIG. 3 when the idling stop condition is satisfied, the internal pressure of the actuator 33 is required to close the waste gate valve 31. Since it takes too much time to reach a negative pressure, it can be said that the engine response cannot be improved upon restart. However, if the residual negative pressure of the brake booster 42 is equal to or higher than the predetermined value Px in FIG. 3 when the idling stop condition is satisfied, the internal pressure of the actuator 33 is reduced to a negative pressure necessary for closing the waste gate valve 31. Since it can be reached quickly, it can be said that the engine response can be improved upon restart.

  For this reason, the threshold value for determining the residual negative pressure of the brake booster 42, which is an idling stop execution permission condition, may be set to the above-described Px when it is necessary to improve the engine response upon subsequent restart. In addition, when there is no need to improve the engine response at the time of a subsequent restart, it can be said that it may be set appropriately on the side smaller than Px.

  Therefore, when it is necessary to improve the engine response, the threshold value may be set to an appropriate value higher than the residual negative pressure of the brake booster 42 that can ensure the braking force necessary for stopping the vehicle. It can be said that it is preferable.

  Next, an example of the control procedure of the eco-run control by the control device 100 in this embodiment will be described in detail with reference to the flowchart of FIG. The processing of this flowchart is started when the engine 1 is started, for example, and is entered every predetermined cycle (several msec).

  First, in step S1, it is determined whether or not the idling stop is being executed by determining whether or not the engine stop flag is “1”. This engine stop flag is set to “1” when the engine 1 is stopped (including other than idling stop), and is “0” when the engine 1 is started (including other than restart due to idling stop cancellation). Reset to.

  If the engine stop flag is “0”, a negative determination is made in step S1, and the process proceeds from the following steps S2 to S8. If it is “1”, an affirmative determination is made in step S1. Then, the process proceeds from step S9 to step S11.

  First, the flow from step S2 to step S8 will be described. In step S2, it is determined whether an idling stop condition by eco-run control is satisfied.

  If the idling stop condition is not satisfied, a negative determination is made in step S2, and this flowchart is terminated. On the other hand, if the idling stop condition is satisfied, an affirmative determination is made in step S2, and the process proceeds to the subsequent step S3.

  In this step S3, it is predicted whether or not the waste gate valve 31 needs to be closed in order to improve the engine response when restarting from the idling stop.

  When the waste gate valve 31 needs to be closed when restarting from the idling stop, the power mode is selected when the idling stop condition is satisfied (the power switch 66 is turned on). Or when the vehicle direction indicator (not shown) is operated when the vehicle is stopped, the operating direction of the direction indicator coincides with the steering angle direction of the vehicle handle (not shown). If you are. Therefore, in the step S3, these situations are examined.

  Here, when it is predicted that it is not necessary to improve the engine response at the time of restart, a negative determination is made in step S3, and in step S4, the threshold value in step S6 below is set to a normal threshold value. On the other hand, when it is predicted that it is necessary to improve the engine response at the time of restart, an affirmative determination is made in step S3, and in step S5, the threshold value in step S6 below is set to a threshold value higher than the normal threshold value. The normal threshold value and the threshold value higher than the normal value may be appropriately set based on the capacity of the pressure accumulating tank 34 to be used as described with reference to FIG.

  After executing Steps S4 and S5, both proceed to Step S6. In step S6, it is determined whether an idling stop execution permission condition is satisfied. The idling stop execution permission condition is that the negative pressure required to drive the waste gate valve 31 to the closed side is equal to or greater than a predetermined threshold value.

  In this embodiment, in step S6, the residual negative pressure of the brake booster 42 is detected based on the input of the output signal from the pressure sensor 51, and the detection result is compared with the threshold value. This threshold is set in step S4 or step S5 as described above.

  Here, if the idling stop execution permission condition is not satisfied, a negative determination is made in step S6, and this flowchart is ended. On the other hand, when the idling stop execution permission condition is satisfied, an affirmative determination is made in step S6, the idling stop is executed in the subsequent step S7, and the engine stop flag is set to "1" in the subsequent step S8. Then, this flowchart is ended.

  Next, the flow from step S9 to step S10 will be described. In step S9, it is determined whether a restart condition of the engine 1 by the eco-run control is satisfied.

  If the restart condition is not satisfied, a negative determination is made in step S9, and this flowchart is terminated. On the other hand, if the restart condition is satisfied, an affirmative determination is made in step S9, a process for restarting the engine is executed in the subsequent step S10, and the engine stop flag is reset to “0” in the subsequent step S11. Then, this flowchart is ended.

  As is clear from the above description, when the idling stop condition of the eco-run control is satisfied, it is predicted that a negative pressure is required to close the waste gate valve 31 at the time of subsequent restart before the execution thereof. If the negative pressure can be secured, execution of idling stop is allowed.

  In this case, the idling stop is executed when the vehicle is stopped, so that the fuel consumption can be improved. In addition, since the waste gate valve 31 can be quickly closed at the time of restart, it becomes possible to improve the engine response to the acceleration request by the driver when re-starting, so that the driver does not feel uncomfortable. Will be able to contribute to the improvement of drivability.

  On the other hand, when the idling stop condition for the eco-run control is satisfied, it is predicted that a negative pressure for closing the waste gate valve 31 is predicted at the time of the subsequent restart before the execution of the idling stop condition. When the pressure cannot be secured, the idling stop is prohibited.

  In this case, since idling is not stopped when the vehicle is stopped, it is not possible to contribute to improvement of fuel consumption, but it is possible to secure a negative pressure necessary for closing the waste gate valve 31 with the vacuum pump 32 driven by the engine 1 while the vehicle is stopped. Therefore, the waste gate valve 31 can be quickly closed at the time of restart, and it becomes possible to improve the engine response to the driver's acceleration request when re-starting, so the driver feels uncomfortable. It becomes possible to contribute to the improvement of drivability, such as not having to give.

  In such an embodiment, step S6 corresponds to the determination unit described in the claims, steps S4 and S5 correspond to the setting unit described in the claims, and step S7 includes the claims. Corresponds to the execution unit.

  As described above, in the embodiment to which the present invention is applied, when the idling stop of the eco-run control is established, prior to the execution, when it is predicted that the engine response improvement is not required at the subsequent restart, It is possible to perform idling stop as much as possible, but on the other hand, only when it is predicted that engine response improvement will be required at the time of subsequent restart, fuel efficiency is improved by tightening the conditions for allowing idling stop execution It becomes possible to improve the engine response.

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) The engine 1 of the above embodiment may be either a gasoline engine or a diesel engine, and the present invention can also be applied to a hybrid vehicle that uses these engine and motor as a drive source. It is.

  (2) In the above embodiment, the vacuum pump 32 is used as a negative pressure source for both the actuator 33 for driving the waste gate valve and the brake booster 42. However, the vacuum pump 32 is used as a brake booster. The present invention can be applied even to a configuration that is not used as the negative pressure source 42.

  The present invention automatically stops an engine equipped with a supercharger with a waste gate valve that is closed using negative pressure when an idling stop condition is satisfied, and automatically activates the engine when the engine restart condition is satisfied. It is applicable to a control device that restarts automatically.

1 Engine 20 Supercharger 31 Wastegate valve (WGV)
32 Vacuum pump 33 Actuator 34 Accumulation tank 35 Vacuum switching valve (VSV)
37 Negative pressure passage 40 Braking device 41 Brake pedal 42 Brake booster 51 Pressure sensor 66 Power switch 100 Control device

Claims (5)

An engine equipped with a supercharger with a waste gate valve that is closed using negative pressure is automatically stopped when the idling stop condition is satisfied, and the engine is automatically restarted when the restart condition is satisfied. A control device,
A negative pressure source for generating a negative pressure for closing the waste gate valve is a vacuum pump driven by the engine;
When the idling stop condition is satisfied, a determination unit that permits the idling stop to be executed on condition that the negative pressure of the negative pressure source is equal to or greater than a predetermined threshold; and
Prior to the determination by the determination unit, when it is predicted that a negative pressure for closing the waste gate valve is required at the time of subsequent restart, the threshold value is set as compared with a case where it is predicted that the negative pressure is not required. An engine control device comprising: a setting unit for setting a high value. The engine control device according to claim 1,
The vacuum pump is configured to be used as a negative pressure source for introducing negative pressure into both an actuator for opening and closing the waste gate valve and a brake booster of a vehicle braking device,
The determination unit permits execution of an idling stop on condition that a residual negative pressure of the brake booster is equal to or greater than a predetermined threshold value. The engine control apparatus according to claim 1 or 2,
The setting unit predicts that the waste gate valve needs to be closed when a power mode for making the engine rotation response to an acceleration request higher than usual when the vehicle is stopped is selected. The engine control device. The engine control apparatus according to claim 1 or 2,
The setting unit needs to close the waste gate valve when the direction indicator of the vehicle is operated when the vehicle is stopped and the operating direction of the direction indicator coincides with the steering angle direction of the steering wheel. An engine control device characterized by predicting. The engine control device according to any one of claims 1 to 4,
The engine control apparatus further includes an execution unit that executes the idling stop when it is determined that the determination unit permits.

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