JP2006177367A - Operation-stop revolution control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation-stop revolution control device for an internal combustion engine, reliably reducing vibration when stopping the revolution of the internal combustion engine. <P>SOLUTION: When the engine is automatically stopped, an engine speed NE is kept as a reference speed NEidl for a reference time (S340-S370) to reduce the cylinder air pressure of the engine. With the cylinder air pressure reduced, a pressure fluctuation in a combustion chamber due to revolution is reduced to reduce a torque fluctuation during revolution stop. Additionally, the speed is gradually reduced during the stop (S420), and so there is no sudden change of creeping force and no vibration of a vehicle. When the speed is gradually reduced, the revolution is immediately stopped right before a resonance speed (S430-S460), therefore preventing vibration due to resonance and vibration due to the rise of the cylinder air pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine operation stop rotation control device that executes rotation control of an internal combustion engine when the operation of the internal combustion engine is stopped using an internal combustion engine rotation means capable of rotating an internal combustion engine in an operation stop state.

  Conventionally, in an internal combustion engine for a vehicle, an economy running system (hereinafter referred to as “eco-run system”) is performed. This eco-run system automatically stops the internal combustion engine when the vehicle stops running at an intersection or the like to improve fuel efficiency, and can start the vehicle by automatically starting the internal combustion engine by rotating the motor during start operation. This is an automatic stop / start system.

However, such an automatic stop of the internal combustion engine is a stop that the driver is not aware of, and thus vibrations caused by the stop of the internal combustion engine may give the driver a sense of incongruity. For example, vibration due to torque fluctuation when the engine stops rotating, vibration due to a sudden decrease in creep force, and the like can be mentioned.
JP-A-10-339182

  In Patent Document 1, the rotation of the internal combustion engine is maintained by the second electric motor at the time of fuel cut at the time of deceleration of the vehicle, and after the vehicle speed becomes zero, the second electric motor is stopped and the first electric motor is driven to obtain the creep force. There are no steps. However, by providing two electric motors in this way, if any of the electric motors is not always driven even when the internal combustion engine is stopped, vibrations are caused by fluctuations in the creep force. Therefore, also in this case, when the rotation of the internal combustion engine is completely stopped, vibration due to torque fluctuation of the internal combustion engine and further vibration due to a sudden decrease in the creep force occur.

  An object of the present invention is to provide an internal combustion engine operation stop rotation control device capable of reliably reducing vibrations when stopping the rotation of an internal combustion engine.

In the following, means for achieving the above object and its effects are described.
The internal combustion engine operation stop rotation control device according to claim 1, wherein the internal combustion engine rotation means capable of rotating the operation stop state internal combustion engine rotation means executes rotation control of the internal combustion engine when the operation of the internal combustion engine is stopped. An engine operation stop rotation control device, wherein the internal combustion engine rotation speed when the operation of the internal combustion engine is stopped in a fully closed state of a throttle valve provided in an intake pipe of the internal combustion engine is determined by a reference rotation speed by the internal combustion engine rotation means. An internal combustion engine stop vibration reducing means for reducing vibration when the internal combustion engine rotation is stopped by stopping the rotation of the internal combustion engine after reducing the in-cylinder air pressure of the internal combustion engine by maintaining the internal combustion engine To do.

  The internal combustion engine stop vibration reducing means maintains the internal combustion engine speed at a reference rotational speed by the internal combustion engine rotating means when the operation of the internal combustion engine is stopped in a fully closed state of a throttle valve provided in an intake pipe of the internal combustion engine. This reduces the cylinder air pressure of the internal combustion engine. By reducing the in-cylinder air pressure, the pressure fluctuation in the combustion chamber due to the rotation is reduced, so that the torque fluctuation is reduced.

  Therefore, the vibration when the rotation of the internal combustion engine is stopped can be reduced by stopping the rotation of the internal combustion engine after reducing the cylinder air pressure of the internal combustion engine. For this reason, the driver does not feel uncomfortable.

  According to a second aspect of the present invention, in the internal combustion engine operation stop rotation control device according to the first aspect, the internal combustion engine stop vibration reduction means determines the internal combustion engine rotation speed when the internal combustion engine operation is stopped during a reference time. Then, after reducing the cylinder air pressure of the internal combustion engine by maintaining the reference rotational speed, the vibration at the time of stopping the rotation of the internal combustion engine is reduced by stopping the rotation of the internal combustion engine.

  One method for reducing the in-cylinder air pressure of the internal combustion engine so that the vibration at the time of the internal combustion engine rotation stop can be reduced by using the internal combustion engine speed for the reference time as described herein. To maintain. The reference time and the reference rotational speed may be fixed values, or may be set according to the operating state of the internal combustion engine immediately before the stoppage of operation or the current driving state of auxiliary machinery and the like.

  Therefore, the vibration when the rotation of the internal combustion engine is stopped can be reduced by stopping the rotation of the internal combustion engine after reducing the cylinder air pressure of the internal combustion engine. For this reason, the driver does not feel uncomfortable.

  The internal combustion engine stoppage rotation control device according to claim 3, wherein the internal combustion engine stop time vibration reducing means is configured to stop the internal combustion engine operation until the intake pipe pressure reaches a reference intake pressure. After the internal combustion engine rotation speed is maintained at the reference rotation speed, the rotation of the internal combustion engine is stopped to reduce vibration when the internal combustion engine rotation is stopped.

  One method for reducing the cylinder air pressure of the internal combustion engine so as to reduce the vibration when the internal combustion engine stops rotating is as described here until the intake pipe pressure reaches the reference intake pressure. The internal combustion engine speed when the operation is stopped is maintained at the reference speed. The reference intake pressure and the reference rotation speed may be fixed values, or may be set according to the operating state of the internal combustion engine immediately before the stop of operation or the current driving state of auxiliary machinery.

  Since the determination is made by detecting the intake pipe pressure in this way, it is possible to determine the reduction of the cylinder air pressure more reliably and early. Therefore, it is possible to stop the rotation of the internal combustion engine by driving the internal combustion engine rotation means at an early stage, further improving the fuel consumption and not causing the driver to feel uncomfortable.

  The internal combustion engine operation stop rotation control device according to claim 4, wherein the internal combustion engine stop vibration reducing means is configured to stop rotation of the internal combustion engine from a rotation state at a reference rotation speed. When performing the above, the number of revolutions is gradually reduced.

  The internal combustion engine stop vibration reducing means gradually reduces the rotational speed when the internal combustion engine is stopped from the reference rotational speed. As a result, the creep force is gradually reduced, so that vibrations can be prevented from occurring in a vehicle or the like in which the internal combustion engine is mounted. For this reason, the driver does not feel uncomfortable.

  6. The internal combustion engine stoppage rotation control device according to claim 5, wherein the internal combustion engine stop time vibration reducing means is configured to reduce the rotation of the internal combustion engine that is gradually decreased immediately before the resonance speed. It is characterized by stopping immediately.

  Even when the rotation of the internal combustion engine is at the resonance rotational speed, if the rotational speed is gradually decreased, vibrations due to resonance may occur conversely. Further, if the rotational speed is gradually decreased until the rotation stops, the air pressure in the cylinder rises due to air leakage from the throttle valve, so that torque fluctuation cannot be suppressed.

  Accordingly, when the rotational speed is gradually decreased, if it comes immediately before the resonant rotational speed, vibration can be prevented more effectively by immediately stopping the rotation of the internal combustion engine. Moreover, since the creep force is small immediately before the resonance rotational speed, there is no large step in the creep force even if the rotation of the internal combustion engine is stopped immediately, and vehicle vibration can be prevented. For this reason, the driver does not feel uncomfortable.

  The internal combustion engine stop vibration reducing means stops the rotation of the internal combustion engine before the rotation speed of the internal combustion engine whose rotation is controlled decreases to the resonance speed when the rotation of the internal combustion engine is stopped after the rotation control. ing. Therefore, since the rotation is not controlled in a state where the rotation of the internal combustion engine is at the resonance rotational speed, the occurrence of vibration due to resonance is prevented. For this reason, the driver does not feel uncomfortable.

  According to a sixth aspect of the present invention, in the internal combustion engine operation stop rotation control device, in the configuration of the fifth aspect, the internal combustion engine stop vibration reduction means includes a resonance rotation speed detection means for detecting the resonance rotation speed of the internal combustion engine. The rotation of the internal combustion engine is stopped before the rotation speed of the internal combustion engine decreases to the resonance rotation speed detected by the resonance rotation speed detection means.

  The internal combustion engine may be provided with the resonance rotational speed detection means in order to cope with a characteristic variation, a temperature change, a change with time, or the like regarding a mechanism that affects the resonance rotational speed of the internal combustion engine such as a mount. As a result, variations in characteristics, temperature changes, changes with time, etc. can be compensated for, so that the internal combustion engine vibration reduction means reduces the internal combustion engine speed to the resonance speed detected by the resonance speed detection means. By configuring the internal combustion engine to stop rotating before, vibration can always be prevented appropriately.

  In the internal combustion engine operation stop rotation control device according to claim 7, in the configuration according to claim 6, the resonance rotational speed detection means extracts a resonance frequency from vibration at the time of internal combustion engine rotation stop, and based on the resonance frequency. The resonance rotational speed of the internal combustion engine is determined.

  In this way, the resonance rotation speed detection means can be configured to extract the resonance frequency from the vibration when the internal combustion engine stops rotating, and to determine the resonance rotation speed of the internal combustion engine based on the resonance frequency. As a result, it is possible to obtain a resonance rotational speed that appropriately compensates for characteristic variations, temperature changes, changes with time, and the like. Therefore, the internal combustion engine stop vibration reducing means can obtain the resonance rotational speed information that can accurately determine the internal combustion engine vibration, and can always appropriately prevent the vibration.

  In the internal combustion engine stoppage rotation control device according to claim 8, in the configuration according to claim 5, the internal combustion engine stoppage vibration reducing means includes an internal combustion engine stop state vibration reducing means for detecting a resonance state of the internal combustion engine. By reducing the engine speed, the rotation of the internal combustion engine is stopped before the resonance state detected by the resonance state detecting means becomes larger than the reference vibration state.

  By providing the resonance state detection means for detecting the resonance state of the internal combustion engine in this way, the internal combustion engine stop vibration reducing means stops the rotation of the internal combustion engine before the resonance state becomes larger than the reference vibration state. Can be configured.

  Therefore, since the internal combustion engine stop vibration reducing means can always cope with the internal combustion engine vibration accurately, it is possible to effectively compensate for variations in characteristics, temperature changes, changes with time, etc., and always prevent vibrations appropriately. it can.

[Embodiment 1]
FIG. 1 is a system configuration diagram of a vehicle internal combustion engine to which the above-described invention is applied and a control device therefor. Here, a gasoline engine (hereinafter referred to as “engine”) 2 is used as the internal combustion engine.

  The output of the engine 2 is output from the crankshaft 2a of the engine 2 to the output shaft 6a side via a torque converter 4 and an automatic transmission (hereinafter referred to as “A / T”) 6, and finally the wheels Is transmitted to. In addition to the driving force transmission system from the engine 2 to the wheels, the output of the engine 2 is transmitted to the belt 14 via the pulley 10 connected to the crankshaft 2a. The other pulleys 16 and 18 are rotated by the rotational force transmitted by the belt 14. The pulley 10 is provided with an electromagnetic clutch 10a, which is turned on (connected) and turned off (cut off) as necessary, so that transmission / non-transmission of output can be switched between the pulley 10 and the crankshaft 2a. .

  Of the pulleys 16 and 18, the pulley 16 is connected to the rotating shaft of the auxiliary machinery 22 so that it can be driven by the rotational force transmitted from the belt 14. Examples of the auxiliary machinery 22 include an air conditioner compressor, a power steering pump, an engine cooling water pump, and the like. Although shown as one auxiliary machine 22 in FIG. 1, in reality, one or more of an air conditioner compressor, a power steering pump, an engine cooling water pump, and the like exist, and each has a pulley to provide a belt. 14 is configured to rotate in conjunction with 14. In the first embodiment, it is assumed that an air conditioner compressor, a power steering pump, and an engine cooling water pump are provided as the auxiliary machinery 22.

  Further, a motor generator (hereinafter referred to as “M / G”) 26 is interlocked with the belt 14 by the pulley 18. The M / G 26 functions as a generator (“power generation mode” or “regeneration mode”) as necessary, thereby converting the rotational force of the engine 2 transmitted from the pulley 18 into electric energy. Further, the M / G 26 functions as a motor (“drive mode”) as necessary to rotate the belt 14 via the pulley 18 to rotate one or both of the engine 2 and the auxiliary machinery 22.

  Here, the M / G 26 is electrically connected to the inverter 28. When the M / G 26 is set to the power generation mode or the regenerative mode, the inverter 28 is switched to switch the low-voltage power supply from the M / G 26 to the high-voltage power supply (here, 36 V) battery 30 and via the DC / DC converter 32. The battery 34 is switched to be a power source for the ignition system, meters, ECUs (electronic control units), and the like so that the battery 34 (12V in this case) is charged with electric energy.

  When the M / G 26 is set to the “driving mode”, the inverter 28 supplies power to the M / G 26 from the high-voltage power supply battery 30 that is a power source, thereby driving the M / G 26 and the pulley 18 and the belt. 14, when the engine is stopped, the auxiliary machinery 22 is rotated, and at the time of automatic start, automatic stop or vehicle start, the crankshaft 2 a is rotated. The inverter 28 can adjust the rotational speed of the M / G 26 by adjusting the supply of electric energy from the high-voltage power supply battery 30.

  A starter 36 is provided to start the engine during cold start. The starter 36 is supplied with electric power from the low-voltage power supply battery 34 and rotates the ring gear to start the engine 2.

  The A / T 6 is provided with an electric hydraulic pump 38 to which electric power is supplied from the low-voltage power supply battery 34, and supplies hydraulic oil to the hydraulic control unit inside the A / T 6. This hydraulic oil adjusts the operating states of the clutch, brake, and one-way clutch inside the A / T 6 by a control valve in the hydraulic pressure control unit, and switches the shift state as necessary.

  The eco-run ECU 40 executes on / off switching of the electromagnetic clutch 10a, mode control of the M / G 26, the inverter 28, control of the starter 36, and other control of the storage amount for the batteries 30 and 34 (not shown). Further, driving on / off of the auxiliary machinery 22 excluding the water pump, driving control of the electric hydraulic pump 38, shift control of A / T6, fuel injection control by the fuel injection valve (intake port injection type or in-cylinder injection type) 42, electric motor The opening degree control of the throttle valve 46 provided in the intake pipe 2b by 44 and other engine control are executed by the engine ECU 48. In addition, by providing a VSC (Vehicle Stability Control) -ECU 50, automatic control of the brakes of each wheel is also executed.

  The eco-run ECU 40 detects the rotation speed of the rotation shaft of the M / G 26 from the rotation speed sensor built in the M / G 26, whether the driver has started the eco-run system, and other data from the eco-run switch. Further, the engine ECU 48 detects the engine cooling water temperature THW from the water temperature sensor, the accelerator pedal depression state from the idle switch, the accelerator opening ACCP from the accelerator opening sensor, the steering angle θ of the steering from the steering angle sensor, the vehicle speed SPD from the vehicle speed sensor, The throttle opening sensor 46a detects the throttle opening TA, the shift position SHFT from the shift position sensor, the engine speed sensor detects the engine speed NE, the air conditioner switches on / off operation, and other data for engine control, etc. Yes.

  The VSC-ECU 50 detects operation data of the brake pedal 52 for braking control or the like. The brake pedal 52 is provided with a brake switch 52 a and outputs a signal representing the depression state BSW of the brake pedal 52 to the VSC-ECU 50. That is, the brake switch 52a outputs an off signal when the brake pedal 52 is not depressed, and an on signal when the brake pedal 52 is depressed.

  A brake booster 56 is provided as a booster that increases the depression force of the brake pedal 52. The brake booster 56 has two pressure chambers 56b and 56c that are defined by a diaphragm 56a. Among these, a brake booster pressure sensor 56d is provided in the first pressure chamber 56b, detects the brake booster pressure BBP in the first pressure chamber 56b, and outputs a signal corresponding to the brake booster pressure BBP. An intake negative pressure is supplied to the first pressure chamber 56b from the surge tank 2c via the check valve 56e. This check valve 56e allows air flow from the first pressure chamber 56b to the surge tank 2c, but prohibits reverse flow.

  The brake booster 56 functions as follows. That is, when the brake pedal 52 is not depressed, the negative pressure control valve 56f provided in the brake booster 56 introduces the negative pressure in the first pressure chamber 56b into the second pressure chamber 56c. Therefore, since the first pressure chamber 56b and the second pressure chamber 56c are in the same negative pressure state, the diaphragm 56a is pushed back toward the brake pedal 52 by the spring 56g. For this reason, the push rod 56h interlocked with the diaphragm 56a does not push the piston (not shown) in the master cylinder 56i.

  On the other hand, when the brake pedal 52 is depressed, the negative pressure control valve 56f shuts off between the first pressure chamber 56b and the second pressure chamber 56c in conjunction with the input side rod 56j provided on the brake pedal 52, Air is introduced into the second pressure chamber 56c. As a result, a pressure difference is generated between the first pressure chamber 56b in the intake negative pressure state and the second pressure chamber 56c at atmospheric pressure. For this reason, the stepping force on the brake pedal 52 is doubled, and the diaphragm 56a pushes the push rod 56h toward the master cylinder 56i against the urging force of the spring 56g. As a result, the piston in the master cylinder 56i is pushed and braking is performed.

  When the brake pedal 52 is stepped back, the negative pressure control valve 56f blocks the communication between the second pressure chamber 56c and the outside air in conjunction with the input side rod 56j provided on the brake pedal 52, and the first pressure Communication between the chamber 56b and the second pressure chamber 56c is established. As a result, intake negative pressure is introduced from the first pressure chamber 56b into the second pressure chamber 56c. Therefore, the first pressure chamber 56b and the second pressure chamber 56c have the same pressure. Therefore, the diaphragm 56a moves to the brake pedal 52 side by the urging force of the spring 56g and returns to the original non-braking state.

  Each of the ECUs 40, 48, and 50 described above is configured with a microcomputer at the center, and the CPU executes necessary arithmetic processing in accordance with a program written in the internal ROM, and based on the calculation result. Various controls are executed. These arithmetic processing results and the data detected as described above are exchanged as necessary between the ECUs 40, 48, and 50 capable of mutual data communication. As a result, the ECUs 40, 48 and 50 can execute control in conjunction with each other.

  Next, vehicle drive control executed by the eco-run ECU 40 will be described. Among the controls described below, the automatic stop process and the automatic start process are executed when the driver turns on the eco-run switch.

  The automatic stop process is shown in the flowchart of FIG. This process is a process that is repeatedly executed in a short cycle. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When this automatic stop process is started, first, an operation state for determining execution of automatic stop is read (S110). For example, the engine coolant temperature THW detected from the water temperature sensor, the accelerator pedal depression / non-depression detected from the idle switch, the voltages of the batteries 30 and 34, the brake pedal 52 depression / non-depression detected from the brake switch 52a, and the vehicle speed sensor The detected vehicle speed SPD and the like are read into the RAM work area inside the eco-run ECU 40.

  Next, it is determined whether or not an automatic stop condition is satisfied from these operating states (S120). For example, (1) the engine 2 is warmed up and not overheated (the engine cooling water temperature THW is lower than the water temperature upper limit and higher than the water temperature lower limit), and (2) the accelerator pedal is not depressed. State (idle switch is on), (3) state where the amount of charge of batteries 30 and 34 is at a required level, (4) state where brake pedal 52 is depressed (brake switch 52a is on), and ( 5) It is determined that the automatic stop condition is satisfied when the conditions (1) to (5) that the vehicle is stopped (the vehicle speed SPD is 0 km / h) are all satisfied.

If any one of the above conditions (1) to (5) is not satisfied, the automatic stop condition is not satisfied (“NO” in S120), and the process is temporarily terminated.
On the other hand, if the driver stops the vehicle at an intersection, for example, and the automatic stop condition is satisfied (“YES” in S120), the traveling M / G control process is stopped (S130). This running M / G control process is a process that is started in an automatic start process (FIG. 5) described later. Specifically, the traveling M / G control process sets the M / G 26 in the power generation mode during normal traveling, and recovers the traveling energy by setting the M / G 26 in the regeneration mode when the vehicle is decelerated during fuel deceleration. This is a process of assisting the rotation of the engine 2 immediately after returning from the cut.

  Next, an engine stop process is performed (S140). That is, when the fuel cut instruction is issued from the eco-run ECU 40 to the engine ECU 48, the fuel injection of the fuel injection valve 42 is stopped, and the throttle valve 46 is fully closed. As a result, the combustion in the engine combustion chamber is stopped, and the operation of the engine 2 is stopped.

Next, execution of an engine stop M / G drive process (FIG. 3) described later is set (S150). In this way, this process is once ended.
The M / G driving process when the engine is stopped is shown in the flowchart of FIG. This process is a process that is started by executing step S150 and is repeatedly executed in a short cycle.

  When the engine stop M / G drive process is started, it is first determined whether or not a vibration reduction process end flag Xstop indicating that the vibration reduction process when the engine is stopped is “OFF” (S210). The vibration reduction process end flag Xstop is set to “OFF” at the time of initial setting when the eco-run ECU 40 is turned on and when an automatic start condition is satisfied in an automatic start process (FIG. 5) described later.

  First, since Xstop = “OFF” (“YES” in S210), first, the engine ECU 48 is instructed to prohibit the air conditioner from being turned on (S215). As a result, if the air conditioner is turned on, the engine ECU 48 cuts off the air conditioner compressor and the pulley 16 and stops driving the air conditioner.

  Next, crankshaft rotation processing (S220) is executed. Details of the crankshaft rotation process are shown in FIG. In the crankshaft rotation process, first, the electromagnetic clutch 10a provided in the pulley 10 is turned on (S310), and the M / G 26 is set in the drive mode (S320). Note that the process of step S310 includes a case where the on-state is maintained if the electromagnetic clutch 10a is already on. The same applies to other processes for turning on the electromagnetic clutch 10a.

  Then, it is determined whether or not the rotational speed gradual reduction start flag Xdown is “OFF” (S330). Note that the rotational speed gradual decrease start flag Xdown is set to “OFF” at the time of initial setting when the eco-run ECU 40 is turned on and when an automatic start condition is satisfied in an automatic start process (FIG. 5) described later.

  First, since Xdown = “OFF” (“YES” in S330), the target idle speed NEid (for example, 600 rpm) is set as the target engine speed NEt of the engine 2 (S340). Then, the output control of the M / G 26 is performed by the inverter 28 so that the engine speed NE becomes the target speed NEt (S350). That is, the control of rotating the crankshaft 2a of the engine 2 through the pulley 18, the belt 14, and the pulley 10 and rotating the engine 2 to the same rotational speed as the idle rotation is started by the output of the M / G 26.

  Next, it is determined whether or not the actual engine speed NE has reached the target engine speed NEt (S360). If the actual engine speed NE has not yet reached the target engine speed NEt (“NO” in S360), this process is temporarily terminated.

  Thereafter, by repeating Steps S340 and S350, the engine speed NE is controlled to the target speed NEt by the output control (S350) of the M / G 26. Once the engine speed NE has reached the target speed NEt (“YES” in S360), it is then determined whether or not the reference time has elapsed since the engine speed NE has reached the target speed NEt. It is determined (S370). This reference time is, for example, 0.5 seconds. Until the reference time has elapsed (“NO” in S370), steps S340 and S350 are repeated.

  When the reference time has elapsed when the engine 2 is forcibly maintained at the idling speed level by driving the M / G 26 ("YES" in S370), the brake booster pressure sensor 56d is then used. It is determined whether or not the detected brake booster pressure BBP is equal to or lower than the reference pressure Px (S380). The reference pressure Px represents a pressure at which the boosting function of the brake pedal force can be sufficiently exerted even if the brake booster 56 depresses the brake pedal 52 immediately after the engine rotation stops.

  If BBP> Px (“NO” in S380), it is next determined whether or not a limit time has elapsed since the engine speed NE reached the target speed NEt (S390). This limit time is, for example, 3 seconds. Until the time limit has elapsed (“NO” in S390), steps S340 and S350 are repeated. If BBP ≦ Px (“YES” in S390), “ON” is set to the rotational speed gradual decrease start flag Xdown (S400), and this process is temporarily terminated.

  If BBP ≦ Px has already been reached when the reference time has passed (“YES” in S370) (“YES” in S380), “ON” is immediately set to the rotational speed gradual reduction start flag Xdown (S400). This processing is once completed.

  The reference time mentioned above is sufficient in the engine cylinder to prevent vibration when the rotation of the engine 2 is stopped by forcibly rotating the crankshaft 2a by the M / G 26 with the throttle valve 46 fully closed. This is the time provided to complete the air pressure drop. This reference time varies depending on the type of engine and the state of the air conditioner and the electrical load until just before, but is previously determined by experiment to obtain the time until the air pressure can surely prevent vibration.

  On the other hand, the limit time is for avoiding the amount of power stored in the high-voltage power supply battery 30 when the brake booster pressure BBP does not decrease to the reference pressure Px because the driver has operated the brake pedal 52, for example. It is the time provided for.

  In this way, when the rotational speed gradual decrease start flag Xdown = “ON” (S400), it is determined as “NO” in step S330 in the next control cycle. Next, whether or not there is a drive request for the power steering pump, that is, whether or not the steering power is high or the power steering hydraulic pressure is high during steering, or when the steering is held and stopped in a high load state. Is determined (S410).

  If there is no request for driving the power steering pump (“NO” in S410), then the target rotational speed NEt is calculated as shown in the following equation 1 (S420).

(Equation 1)
NEt ← NEt-dNE ... [Formula 1]
Here, the gradually changing value dNE is a value for gradually decreasing the target rotational speed NEt.

  Then, it is determined whether or not the target rotational speed NEt has become equal to or lower than the limit rotational speed NEs by the calculation of Equation 1 (S430). This limit rotational speed NEs is set as the rotational speed immediately before the engine 2 decreases to the resonant rotational speed. Here, for example, it is set to 400 rpm.

  If NEt> NEs (“NO” in S430), then output control of the M / G 26 is executed so that the engine speed NE becomes the target speed NEt (S440). Then, this process is temporarily terminated.

  Thereafter, if NEt ≦ NEs is obtained by repeating step S420 (“YES” in S430), then the value of the limit rotational speed NEs is set as the target rotational speed NEt (S445). Then, it is determined whether or not the engine speed NE has reached the target speed NEt (S450). If the engine speed NE has not yet reached the target speed NEt (“NO” in S450), the process is temporarily terminated after the process of step S440.

  If the engine speed NE has reached the target speed NEt (“YES” in S450), the vibration reduction process end flag Xstop is set to “ON” (S460), and this process is temporarily ended.

  In the state where NEt> NEs (“NO” in S430), when it is determined that there is a drive request for the power steering pump in step S410 while the processes in steps S420 and S440 are repeated (“ YES "), only step S440 is executed and the process is temporarily terminated. Thus, since step S420 is not executed, the target rotational speed NEt maintains the value of the target rotational speed NEt at that time as long as it is determined as “YES” in step S410. Thereafter, when there is no request for driving the power steering pump (“NO” in S410), the processing (S420, S430) for gradually decreasing the target rotational speed NEt to the limit rotational speed NEs is resumed.

  Since Xstop = “ON” (S460) after the target rotational speed NEt is gradually reduced to the limit rotational speed NEs in this way, “NO” is determined in step S210 (FIG. 3) of the next control cycle. Is done. As a result, the engine ECU 48 is instructed to allow the air conditioner to be turned on (S225). Next, it is determined whether or not there is a request for driving the auxiliary machinery 22 (S230). If there is a drive request for auxiliary equipment ("YES" in S230), the electromagnetic clutch 10a is turned off (S240), and the M / G 26 is set to the drive mode (S250). Note that the process of step S240 includes a case where the off state is maintained if the electromagnetic clutch 10a is already off. The same applies to other processes for turning off the electromagnetic clutch 10a.

  Then, the rotational speed NMGidl, which is a value obtained by converting the idle target rotational speed NEidl to the rotational speed of M / G26, is set in the target rotational speed NMGt of M / G26 (S260). Then, the output control of the M / G 26 is performed by the inverter 28 so that the actual rotational speed NMG of the M / G 26 becomes the target rotational speed NMGt (S270). In this way, this process is once completed. On the other hand, if there is no drive request for auxiliary equipment (“NO” in S230), the function of the M / G 26 is stopped (S280), and this process is temporarily terminated.

  In this way, after the engine speed NE is gradually reduced to the limit speed NEs, the electromagnetic clutch 10a is turned off (S240) or the M / G26 function is stopped (S280). The rotation of the crankshaft 2a is stopped. Therefore, the engine rotation quickly stops at the resonance speed.

  If there is a drive request for the auxiliary machinery 22 after the rotation of the engine 2 is stopped due to the M / G 26 function stop (S280) ("YES" in S230), the M / G 26 is driven, The auxiliary machinery 22 can be rotated through the pulley 18, the belt 14, and the pulley 16 in the same manner as when the engine 2 is in idle rotation. Therefore, even if the engine 2 is stopped, the air conditioner and the power steering can be driven as required. When the M / G 26 is driven when the engine is stopped (S240 to S270), the electromagnetic clutch 10a is in an off state, so that the crankshaft 2a of the engine 2 rotates even when the M / G 26 is driven. There is nothing to do. Therefore, wasteful power consumption can be prevented and fuel consumption can be improved.

Next, the automatic start process is shown in the flowchart of FIG. This process is a process that is repeatedly executed in a short cycle.
When the automatic start process is started, first, an operation state for determining execution of automatic start is read (S510). Here, for example, the same as the data read in step S110 of the automatic stop process (FIG. 2), the engine coolant temperature THW, the state of the idle switch, the charged amount of the batteries 30, 34, the state of the brake switch 52a, the vehicle speed SPD, etc. Are loaded into the RAM work area.

  Next, it is determined from these operating states whether or not the automatic start condition is satisfied (S520). For example, under the condition that the engine is stopped by the automatic stop process, (1) the engine 2 is warmed up and not overheated (the engine cooling water temperature THW is lower than the water temperature upper limit and the water temperature lower limit Higher than the value), (2) the accelerator pedal is not depressed (idle switch is on), (3) the charged amount of the batteries 30, 34 is at a required level, and (4) the brake pedal 52 is depressed. And (5) one of the conditions (1) to (5) that the vehicle is stopped (the vehicle speed SPD is 0 km / h) is satisfied. If not, it is determined that the automatic start condition is satisfied.

  If the engine is not stopped by the automatic stop process or if all of the above conditions (1) to (5) are satisfied even if the engine is stopped by the automatic stop process, the automatic start condition is not satisfied (S520). "NO"), the process is temporarily terminated.

  If any one of the above conditions (1) to (5) is not satisfied in the engine stop state by the automatic stop process, it is assumed that the automatic start condition is satisfied (“YES” in S520), and the aforementioned M / The G drive process (FIG. 3) is stopped (S530). Then, execution of the M / G drive start start process and the traveling M / G control process is set (S540). Here, the M / G drive start start process is a process for starting the vehicle and starting the engine 2 by driving the M / G 26. In the traveling M / G control process, when the vehicle is normally traveling, the M / G 26 is rotated by the output of the engine 2 to generate electric power, or the traveling energy of the vehicle is recovered by the M / G 26 when the fuel is cut when the vehicle is decelerated. It is processing.

  Next, the vibration reduction process end flag Xstop is set to “OFF” (S550), the rotation speed gradual reduction start flag Xdown is set to “OFF” (S560), and this process is temporarily ended.

  An example of the processing executed as described above is shown in the timing chart of FIG. As indicated by the solid line, before the time t0, the engine 2 is operated at an idle speed corresponding to the load state at that time by idle speed control executed by the engine ECU 48 after the vehicle stops. When the automatic stop condition is satisfied at time t0, the fuel injection from the fuel injection valve 42 is stopped, and the engine 2 stops its operation. Then, the engine stop M / G driving process (FIGS. 3 and 4) drives the M / G 26 to set the engine target rotational speed NEt to the idle target rotational speed NEidl (= 600 rpm), and this rotational state continues for the reference time. To do. When the engine 2 is forcibly rotated by the M / G 26, the throttle valve 46 is in the fully closed state, so that the air pressure in the cylinder is sufficiently low, and the air pressure Pa is less than or equal to the air pressure Pa sufficient to prevent vibration when the engine rotation is stopped. .

  At time t1 after the reference time, the brake booster pressure BBP is already equal to or lower than the reference pressure Px, and thereafter the engine target speed NEt is gradually decreased. Accordingly, the creep force transmitted to the wheel side through the torque converter 4 and A / T 6 in the non-lock-up state is gradually reduced.

  When the engine target speed NEt reaches the limit speed NEs (= 400 rpm) at time t2, if there is no request for driving the auxiliary machinery 22, the driving of the M / G 26 is stopped, and the driving request for the auxiliary machinery 22 is requested. If there is, the electromagnetic clutch 10a is turned off. Therefore, the rotation of the engine 2 stops.

  When steering is performed (time t11) during the period (t1 to t2) in which the engine target speed NEt gradually decreases, a drive request for the power steering pump is generated. Until the drive request for the power steering pump disappears (time t12), the target rotational speed NEt when the drive request for the power steering pump is generated is maintained. This causes the power steering pump to function at M / G26. If the drive request for the power steering pump disappears (time t12), the engine target speed NEt is gradually decreased to the limit speed NEs (time t13), and if there is no drive request for the auxiliary machinery 22, M / The driving of G26 is stopped, and the electromagnetic clutch 10a is turned off if there is a driving request for the auxiliary machinery 22. Therefore, the rotation of the engine 2 stops.

  In the configuration of the first embodiment described above, M / G 26 corresponds to the internal combustion engine rotating means, and steps S310 to S370, S400, and S420 to S460 correspond to the processing as the internal combustion engine stop vibration reducing means.

According to the first embodiment described above, the following effects can be obtained.
(I). When the engine 2 is automatically stopped, the engine rotational speed NE is maintained at the reference rotational speed (here, the idle target rotational speed NEidl) for a reference time, thereby reducing the cylinder air pressure of the engine 2. By reducing the in-cylinder air pressure in this way, the pressure fluctuation in the combustion chamber due to the rotation is reduced, so that the torque fluctuation when the rotation is stopped is reduced. Therefore, the vibration when the engine rotation is stopped can be reduced by stopping the rotation of the engine 2 after the cylinder air pressure of the engine 2 is reduced. For this reason, the driver does not feel uncomfortable.

  (B). When stopping the rotation of the engine 2 from the rotation state at the idle target rotation speed NEidl, the engine rotation speed NE is gradually decreased. As a result, the creep force is slowly reduced, so that the vehicle can be prevented from vibrating. For this reason, the driver does not feel uncomfortable.

(C). Further, the decrease in the engine speed that is gradually performed ends immediately before the resonance speed (200 to 300 rpm in this case) and stops the engine rotation.
Even when the engine rotational speed NE is at the resonance rotational speed, if the rotational speed is gradually decreased, vibration due to resonance occurs. Further, if the engine speed NE is gradually decreased until the engine rotation stops, the air pressure in the cylinder rises due to the air leakage from the throttle valve 46, and thus torque fluctuation cannot be suppressed.

  Therefore, when the engine speed NE is gradually decreased and immediately before the resonance speed, the engine rotation by driving the M / G 26 is immediately stopped, so that vibration can be prevented more effectively. . Moreover, since the creep force is small immediately before the resonance rotational speed, there is no large step in the creep force even if the engine rotation is stopped immediately, and vehicle vibration can be prevented. For this reason, the driver does not feel uncomfortable.

[Embodiment 2]
The second embodiment is different from the first embodiment in that the crankshaft rotation process shown in FIG. 7 is executed instead of the crankshaft rotation process (FIG. 4). The surge tank 2c is provided with an intake pressure sensor to detect the intake pipe pressure PM and output it to the engine ECU 48. The other configuration is the same as that of the first embodiment unless otherwise described. 7 is different from the crankshaft rotation process (FIG. 4) of the first embodiment in that steps S372 and S374 are executed instead of step S370. Therefore, the following description will focus on steps S372 and S374.

  When the crankshaft rotation process (FIG. 7) is started and the engine speed NE once reaches the target speed NEt by driving the M / G 26 (“YES” in S360), then the intake pipe pressure PM Is determined to be equal to or lower than the reference intake pressure Pi (S372). This reference intake pressure Pi indicates a state in which the air pressure in the engine cylinder is sufficiently lowered to prevent vibration when the engine 2 stops rotating.

  If PM> Pi (“NO” in S372), it is next determined whether or not a limit time has elapsed since the engine speed NE reached the target speed NEt (S374). The limit time in step S374 is, for example, a time set in a range of 0.5 to 3 seconds. Until the limit time has elapsed (“NO” in S374), steps S340 and S350 are repeated thereafter. If PM ≦ Pi (“YES” in S374), it is then determined whether or not the brake booster pressure BBP detected by the brake booster pressure sensor 56d has become equal to or lower than the reference pressure Px (S380). Thereafter, the same processing as in the first embodiment is performed.

In the configuration of the second embodiment described above, steps S310 to S370, S400, and S420 to S460 correspond to processing as vibration reduction means when the internal combustion engine is stopped.
According to the second embodiment described above, the following effects can be obtained.

  (I). When the engine 2 is automatically stopped, the cylinder air pressure of the engine 2 is reduced by maintaining the engine speed NE at the reference speed until the intake pipe pressure PM becomes equal to or lower than the reference intake pressure Pi. By reducing the in-cylinder air pressure in this way, the pressure fluctuation in the combustion chamber due to the rotation is reduced, so that the torque fluctuation when the rotation is stopped is reduced. Therefore, the vibration when the engine rotation is stopped can be reduced by stopping the rotation of the engine 2 after the cylinder air pressure of the engine 2 is reduced.

  Here, since the decrease in the air pressure in the cylinder is determined by the detected value of the intake pipe pressure PM, it is possible to determine the decrease in the cylinder air pressure more reliably and early. For this reason, it is possible to quickly stop the internal combustion engine rotation while suppressing the vibration. Therefore, engine rotation by driving the M / G 26 can be stopped early, fuel efficiency is further improved, and the driver does not feel uncomfortable.

(B). The effects (b) and (c) of the first embodiment are produced.
[Embodiment 3]
In the third embodiment, when the M / G function stop process (S280) in the engine stop M / G drive process (FIG. 3) is executed, the M / G stop shown in FIG. 8 is performed instead of the process of step S280. The point that the driving of the M / G 26 is stopped by the processing is different from the first embodiment. The other configuration is the same as that of the first embodiment unless otherwise described.

  The M / G stop process shown in FIG. 8 is an interrupt process that is repeatedly executed in a short period in step S280. When this M / G stop process is started, it is first determined whether or not the current value of the crank counter CCRNK is any one of “0, 4, 8, 12, 16, 20” ( S610).

  Here, the crank counter CCRNK is a counter that is counted up every crank angle of 30 ° between 0 and 23 as shown in FIG. 9 by processing separately performed by the engine ECU 48, and based on this value. As shown in the figure, the crank angle and the stroke of each cylinder are determined. At the timing when the crank counter CCRNK = 0, the first cylinder # 1 becomes the compression top dead center, and at the timing when the CCRNK = 4, the fifth cylinder # 5 becomes the compression top dead center, and the CCRNK = 8. At the timing, the third cylinder # 3 is at compression top dead center, at the timing when CCRNK = 12, the sixth cylinder # 6 is at compression top dead center, and at the timing when CCRNK = 16, the second cylinder # 2 is compression up At the timing when CCRNK = 20 at the dead point, the fourth cylinder # 4 is set to be the compression top dead center. Therefore, the determination in step S610 determines whether or not any cylinder is in a compression top dead center state.

  If the value of the crank counter CCRNK is not any value of “0, 4, 8, 12, 16, 20” (“NO” in S610), this processing is temporarily terminated as it is. Therefore, the M / G 26 has not been stopped yet.

  By repeating the M / G stop process (FIG. 8), the value of the crank counter CCRNK advances, and the value of the crank counter CCRNK becomes any one of “0, 4, 8, 12, 16, 20”. If “YES” in S610, the power supply to the M / G 26 is then stopped, and the rotational driving force of the M / G 26 with respect to the crankshaft 2a of the engine 2 is stopped (S620). As a result, the rotation of the crankshaft 2a of the engine 2 is stopped.

  Then, an M / G stop process (FIG. 8) is performed to stop the execution of itself (S630), and this process ends. Thereafter, the M / G stop process (FIG. 8) is not executed until the automatic stop condition of the engine 2 is satisfied and the M / G drive process (FIG. 3) is executed when the engine is stopped. .

  Here, an example of a change in the rotational force applied to the crankshaft 2a of the engine 2 before and after the stop of the M / G 26 is shown in the timing chart of FIG. Here, it is assumed that the combustion of the engine 2 has already stopped before the time t1, and the engine 2 is forcibly rotated by the M / G 26. At this time, the rotational force on the crankshaft 2a of the engine 2 fluctuates in a wavy manner due to the action of the in-cylinder pressure for six cylinders with respect to the rotational driving force of the M / G 26. As a result, the angular acceleration of the crankshaft 2a of the engine 2 also fluctuates around 0 as shown in the figure.

  At time t1, step S280 of the engine stop M / G drive process (FIG. 3) is executed, and interrupt execution of the M / G stop process (FIG. 8) is started. When the interrupt execution of the M / G stop process (FIG. 8) is started, since the crank counter CCRNK = 2 (“NO” in S610), the M / G 26 is not stopped.

  When the crank counter CCRNK is incremented while the interrupt execution of the M / G stop process (FIG. 8) is repeated, and the crank counter CCRNK = 4 (“YES” in S610), the M / G 26 stops here. (S620). At the timing when the crank counter CCRNK = 4 (time t2), the increase rate of the rotational force is almost the maximum due to the synthesis of the in-cylinder pressure of the six cylinders, and the angular acceleration of the crankshaft 2a becomes a positive value that is almost the maximum. ing.

  At this timing, the angular acceleration due to the disappearance of the rotational driving force of the M / G 26 is applied to the crankshaft 2a as a negative value. Therefore, the maximum positive angular acceleration generated by the combination of the cylinder pressures of the six cylinders and the negative angular acceleration due to the disappearance of the rotational driving force of the M / G 26 cancel each other, and the M / G 26 becomes as shown in FIG. The absolute value of angular acceleration after stopping is kept small.

  FIG. 11 shows a case where the M / G 26 is immediately stopped at time t1 as a comparative example. At time t1, it is a period during which the rotational force is reduced by the synthesis of the in-cylinder pressure of the six cylinders, and the angular acceleration of the crankshaft 2a is a negative value. For this reason, the negative angular acceleration generated by the synthesis of the in-cylinder pressure of the six cylinders and the negative angular acceleration due to the disappearance of the rotational driving force of the M / G 26 are intensified, and the M / G 26 stops as shown in FIG. After that, the absolute value of angular acceleration is greatly amplified.

  In the configuration of the third embodiment described above, steps S310 to S370, S400, S420 to S460 of the crankshaft rotation process (FIG. 4) and the M / G stop process (FIG. 8) are performed as vibration reduction means when the internal combustion engine is stopped. It corresponds to processing.

According to the third embodiment described above, the following effects can be obtained.
(I). The effects (a), (b) and (c) of the first embodiment are produced.
(B). The stop timing of the M / G 26 is also set to a state where the angular acceleration generated by the synthesis of the in-cylinder pressures of the six cylinders of the engine 2 is positive, particularly the maximum crank angle (compression top dead center of each cylinder). is doing.

  Therefore, the positive angular acceleration and the negative angular acceleration generated by the disappearance of the rotational driving force of the M / G 26 cancel each other, and the absolute value of the angular acceleration after the M / G 26 stops can be kept small. Thereby, the vibration at the time of stopping rotation of engine 2 can be controlled more effectively.

  FIG. 12 shows experimental data when the rotation of the M / G 26 is stopped at the compression top dead center (crank counter CCRNK = 4) of the fifth cylinder # 5. Further, as a comparative example, FIG. 13 shows experimental data in which the rotation of the M / G 26 is stopped at the timing when the negative angular acceleration is generated, specifically, the crank counter CCRNK = 14.

  As can be seen from the figure, when the crank counter CCRNK = 4 in which the positive angular acceleration occurs and the M / G 26 is stopped at the crank counter CCRNK = 14 in which the negative angular acceleration occurs (FIG. 12). It can be seen that the left and right vibration level in the engine mount is lower than in FIG.

  FIG. 14 shows the measurement results of the left and right vibrations in the engine mount that occurred when the rotation of the M / G 26 was stopped by changing the rotation stop timing of the M / G 26. 14A shows the compression top dead center (CCRNK = 0, 4, 8, 12, 16, 20) of each cylinder, and FIG. 14B shows the compression top dead center + 30 ° (CCRNK = 1, 5, 9). , 13, 17, 21), (C) is compression top dead center + 60 ° (CCRNK = 2, 6, 10, 14, 18, 22), and (D) is compression top dead center + 90 ° (CCRNK). = 3, 7, 11, 15, 19, 23), the case where the M / G 26 is stopped is shown.

  As can be seen from the figure, although the increase rate of the rotational force is almost at the maximum timing, that is, the absolute value of the positive angular acceleration is at the maximum timing (A), it can be seen that the vibration when the M / G 26 stops is small. . The rotational force decrease rate is almost the maximum timing, that is, the absolute value of the negative angular acceleration is almost the maximum timing (C), but the vibration when the M / G 26 is stopped is much higher than that of (A). It turns out that it is big.

[Embodiment 4]
In the fourth embodiment, the limit rotation speed NEs used in steps S430 and S445 of the crankshaft rotation process (FIG. 4) of the first embodiment is variable, and the limit rotation speed NEs setting process described below is performed. The point calculated by the eco-run ECU 40 is different from that of the first embodiment. Further, as data used for the limit rotational speed NEs setting process, an acceleration sensor for detecting the vibration of the engine 2 is provided in the cylinder block of the engine 2 to detect the engine vibration in the rolling direction as an acceleration change. This is different from the first embodiment. The other configuration is the same as that of the first embodiment unless otherwise described.

  The limit rotation speed NEs setting process is shown in the flowchart of FIG. This process is performed during the period in which the crankshaft 2a is rotated by driving the M / G 26 after the rotational speed gradual decrease start flag Xdown is set to “ON” in step S400 of the crankshaft rotation process (FIG. 4). Substantial processing is performed.

  When the limit rotational speed NEs setting process in FIG. 15 is started, it is first determined whether or not the rotational speed gradual decrease start flag Xdown is “ON” (S710). If Xdown = “OFF” (“NO” in S710), “OFF” is set to the limit rotational speed setting completion flag Xnes (S720), and this process is temporarily terminated.

  If Xdown = “ON” by executing step S400 of the crankshaft rotation processing (FIG. 4) (“YES” in S710), then whether or not the limit rotational speed setting completion flag Xnes is “OFF”. Is determined (S730). Since Xnes = “OFF” in the initial stage (“YES” in S730), it is next determined whether or not the vibration reduction process end flag Xstop is “ON” (S740). Here, the state determined as “NO” in step S430 or “NO” in step S450 of the crankshaft rotation processing (FIG. 4), that is, the engine speed NE is rotated by driving the M / G 26, and In a state where the engine speed NE is gradually decreasing, Xstop = “OFF” (“NO” in S740). Therefore, as described above, the acceleration is sampled every short time by the acceleration sensor provided in the cylinder block (S750). In this way, this process is once completed.

  Rolling direction in the cylinder block of engine 2 as long as Xdown = “ON” (“YES” in S710), Xnes = “OFF” (“YES” in S730) and Xstop = “OFF” (“NO” in S740) The acceleration sampling continues (S750).

  Thereafter, when the decrease in the engine speed NE by driving the M / G 26 is finished, the vibration reduction process end flag Xstop is set to “ON” (crankshaft rotation process: step S460 in FIG. 4). Therefore, since Xstop = “ON” (“YES” in S740), the FFT operation is next performed on the sampled acceleration data (S760). Thereby, the frequency spectrum of the acceleration is calculated.

  Then, in this frequency spectrum, it is determined whether or not there is a frequency whose vibration intensity represented by the absolute value of acceleration is equal to or higher than the reference intensity (S770). Here, the reference strength is set to a strength at which the acceleration starts to give a sense of discomfort to the vehicle occupant, or a value slightly lower than this strength.

  If the vibration intensity is less than the reference intensity at any frequency obtained by the FFT calculation (“NO” in S770), the decrease correction value NEd is expressed as shown in the following expression 2 with respect to the currently set limit rotational speed NEs. Minute reduction calculation is executed (S780).

(Equation 2)
NEs ← NEs − NEd ... [Formula 2]
Next, “ON” is set to the limit rotational speed setting completion flag Xnes (S790), and this process is temporarily terminated. Thereafter, since Xnes = “ON” (“NO” in S730), no substantial process is performed in the limit rotational speed NEs setting process.

  On the other hand, if the frequency obtained by the FFT calculation has a vibration intensity equal to or higher than the reference intensity (“YES” in S770), the highest frequency among the frequencies equal to or higher than the reference intensity is the maximum frequency fmax. (S800).

  Then, the engine speed corresponding to the maximum frequency fmax is calculated based on the function Fne (may be a map), and the corresponding engine speed is increased and corrected by the increase correction value NEp as shown in the following equation 3. Then, a new limit rotational speed NEs is calculated (S810).

(Equation 3)
NEs <-Fne (fmax) + NEp ... [Formula 3]
By correcting the increase correction value NEp, it is possible to set the limit rotational speed NEs that stops the rotation of the crankshaft 2a before causing the engine 2 to resonate.

  Then, “ON” is set to the limit rotational speed setting completion flag Xnes (S790), and this process is temporarily terminated. Thereafter, since Xnes = “ON” (“NO” in S730), no substantial process is performed in the limit rotational speed NEs setting process.

In the configuration of the fourth embodiment described above, the limit rotational speed NEs setting process (FIG. 15) corresponds to the process as the resonance rotational speed detection means.
According to the fourth embodiment described above, the following effects can be obtained.

(I). The effects (a), (b) and (c) of the first embodiment are produced.
(B). When the engine 2 is stopped, when resonance occurs during a period in which the engine speed NE is gradually decreased by driving the M / G 26, the frequency causing the resonance is detected, and the maximum frequency fmax is detected among these frequencies. Based on the above, the limit rotational speed NEs is set. For this reason, even if the initially set limit rotational speed NEs is not suitable for preventing resonance due to variations in engine mounts, temperature changes, changes with time, or the like, the critical rotational speed NEs is not appropriate. Since the appropriate limit rotational speed NEs is learned and set by the setting process (FIG. 15), vibration can be reliably prevented.

  (C). When resonance does not occur during a period in which the engine speed NE is gradually decreased by driving the M / G 26, the limit speed NEs is decreased. In this way, the limit rotational speed NEs is made as low as possible within a range where resonance does not occur. For this reason, the creep force can be reduced as much as possible. Therefore, even if the engine rotation is stopped immediately from the limit rotational speed NEs, the step difference in the creep force becomes very small and vehicle vibration can be prevented. For this reason, it is possible to more effectively prevent the driver from feeling uncomfortable.

[Embodiment 5]
The fifth embodiment is different from the fourth embodiment in that a limit rotation speed NEs setting process shown in FIG. 16 is executed instead of the limit rotation speed NEs setting process (FIG. 15) of the fourth embodiment. . Other configurations are the same as those in the fourth embodiment unless otherwise specified.

  The limit rotational speed NEs setting process (FIG. 16) will be described. When the limit rotational speed NEs setting process is started, it is first determined whether or not the rotational speed gradual decrease start flag Xdown is “ON” (S910). If Xdown = “OFF” (“NO” in S910), “OFF” is set to the limit rotational speed setting completion flag Xnes (S920), and this process is temporarily terminated.

  If Xdown = “ON” by executing step S400 of the crankshaft rotation processing (FIG. 4) (“YES” in S910), then whether or not the limit rotational speed setting completion flag Xnes is “OFF”. Is determined (S930). Since Xnes = “OFF” in the initial stage (“YES” in S930), it is next determined whether or not the vibration reduction process end flag Xstop is “ON” (S940). Here, the state determined as “NO” in step S430 or “NO” in step S450 of the crankshaft rotation processing (FIG. 4), that is, the engine speed NE is rotated by driving the M / G 26, and In a state where the engine speed NE is gradually decreasing, Xstop = “OFF” (“NO” in S940). Therefore, next, as described above, it is determined whether or not the absolute value of the acceleration detected by the acceleration sensor provided in the cylinder block is equal to or larger than the reference value (S950). Here, the reference value is set to a level at which the acceleration level starts to give a sense of discomfort to the vehicle occupant, or an absolute value of acceleration at a level slightly lower than this.

If the absolute value of the acceleration is less than the reference value (“NO” in S950), this process is temporarily terminated.
After that, when the decrease in the engine speed NE by driving the M / G 26 is finished while the state where the absolute value of the acceleration is less than the reference value continues, “ON” is set to the vibration reduction process end flag Xstop. (Crankshaft rotation process: Step S460 in FIG. 4). Therefore, since Xstop = “ON” (“YES” in S940), next, as shown in the following equation 4, a reduction calculation corresponding to the reduction correction value NEd is executed with respect to the currently set limit rotational speed NEs. (S960).

(Equation 4)
NEs ← NEs − NEd ... [Formula 4]
Next, “ON” is set to the limit rotational speed setting completion flag Xnes (S970), and this process is temporarily terminated. Thereafter, since Xnes = “ON” (“NO” in S930), substantial processing is not performed in the limit rotational speed NEs setting processing.

  On the other hand, if the absolute value of the acceleration is greater than or equal to the reference value before Xstop = “ON” (“YES” in S950), then, as shown in the following equation 5, the current engine speed NE is set. On the other hand, a new limit rotational speed NEs is calculated by performing an increase correction with the increase correction value NEp (S980).

(Equation 5)
NEs ← NE + NEp ... [Formula 5]
Since the absolute value of the acceleration is equal to or greater than the reference value, it indicates that the current engine speed NE is close to the resonance speed or is the resonance speed. Therefore, the limit rotational speed NEs for stopping the rotation of the crankshaft 2a before causing the resonance of the engine 2 can be set by increasing the current engine speed NE with the increase correction value NEp.

  Next, “ON” is set to the limit rotational speed setting completion flag Xnes (S970), and this process is temporarily terminated. Thereafter, since Xnes = “ON” (“NO” in S930), substantial processing is not performed in the limit rotational speed NEs setting processing.

  In the configuration of the fifth embodiment described above, the acceleration sensor is used as the resonance state detecting means, and steps S310 to S370, S400, S420 to S460 of the crankshaft rotation processing (FIG. 4) and the limit rotational speed NEs setting processing (FIG. 16) are performed. This corresponds to processing as vibration reduction means when the internal combustion engine is stopped.

According to the fifth embodiment described above, the following effects can be obtained.
(I). The effects (a), (b) and (c) of the first embodiment are produced.
(B). When the engine 2 is stopped, when resonance occurs or is about to occur during a period in which the engine speed NE is gradually decreased by driving the M / G 26, the limit is based on the engine speed NE at this time. The rotational speed NEs is set. For this reason, even if the initially set limit rotational speed NEs is not appropriate or is not appropriate due to variations in engine mounts, temperature changes, changes with time, etc., limit rotational speed NEs setting processing ( Since an appropriate limit rotational speed NEs is learned and set according to FIG. 16), vibration can be reliably prevented.

  In addition, when resonance occurs or is about to occur within a period in which the engine speed NE is gradually decreased by driving the M / G 26, the limit rotational speed NEs is corrected to increase, so that the crankshaft rotation is immediately performed. This can be reflected in the limit rotational speed NEs of the process (FIG. 4). For this reason, vibration can be prevented quickly.

  (C). If resonance does not occur until the vibration reduction processing end flag Xstop becomes “ON”, the limit rotational speed NEs may be set higher than necessary. For this reason, when resonance does not occur during a period in which the engine speed NE is gradually decreased by driving the M / G 26, the limit speed NEs is decreased. In this way, the limit rotational speed NEs is made as low as possible without causing resonance. For this reason, the creep force can be reduced as much as possible. Therefore, even if the engine rotation is stopped immediately from the limit rotational speed NEs, the step difference in the creep force becomes very small and vehicle vibration can be prevented. For this reason, it is possible to more effectively prevent the driver from feeling uncomfortable.

[Other embodiments]
In the first embodiment, in order to be able to cope with re-depressing of the brake pedal 52 immediately after the rotation of the engine 2 is stopped, the engine rotation stop timing due to the driving of the M / G 26 is set to the reference time. In addition, the determination was made by comparing the brake booster pressure BBP with the reference pressure Px. In addition to this, instead of directly using the value of the brake booster pressure BBP, an appropriate engine forced rotation time that allows the brake booster pressure BBP to be equal to or lower than the reference pressure Px is obtained by experiment, and during this engine forced rotation time, the engine 2 May be forcibly rotated by driving the M / G 26. In this case, when the engine forced rotation time for decreasing the brake booster pressure BBP and the reference time for decreasing the cylinder air pressure, whichever is longer, the rotational speed gradual decrease start flag Xdown is set to “ ON "(S400). Further, the brake booster 56 is determined based on the engine forced rotation time, and in order to prevent vibration, the cylinder air pressure drop may be determined from the degree of intake pressure in the surge tank 2c as in the second embodiment. good.

  In the first and second embodiments, the reference rotational speed of the crankshaft 2a for reducing the in-cylinder air pressure is the idle target rotational speed NEidl. However, it may be any rotational speed that can reduce the in-cylinder air pressure. Other rotational speeds may be used. Further, the reference rotation speed is not limited to the case of showing one rotation speed. For example, the in-cylinder air pressure may be reduced by controlling the rotation speed of the crankshaft 2a so that a certain rotation speed region is set as the reference rotation speed and within the rotation speed region.

  In the first and second embodiments, when the engine is stopped, as long as there is a request for driving the power steering pump due to the presence of step S410 (“YES” in S410), the engine is rotated by driving the M / G 26. In this case, a time limit may be provided for continuing the engine rotation. For example, by providing a time limit, even if there is a drive request for the power steering pump, if the time limit elapses, steps S420 to S460 are made to function again or the electromagnetic clutch 10a is disconnected. Thus, the engine rotation by driving the M / G 26 is not continued for a long time, and the power consumption can be reduced.

  In the first and second embodiments, when the engine is stopped, if there is a drive request for the power steering pump due to the presence of step S410 (“YES” in S410), the target rotational speed NEt at that time is maintained. Although the engine rotation is continued, the target rotational speed NEt may be gradually decreased even if there is a request for driving the power steering pump as long as there is no problem in generating the necessary power steering hydraulic pressure. For example, if there is no problem in generating the required power steering hydraulic pressure even when the engine rotational speed NE is 400 rpm, the target rotational speed NEt is continuously reduced even if there is a request for driving the power steering pump, and the engine rotational speed NE is increased to 400 rpm. At this point, the electromagnetic clutch 10a may be disconnected to stop the rotation of the engine 2 and drive only the auxiliary machinery 22.

  In the third embodiment, the example in which the M / G stop process shown in FIG. 8 is applied to the first embodiment has been described. However, the third embodiment can also be applied to the second embodiment. Further, the M / G stop process shown in FIG. 8 is not combined with the processes of the first and second embodiments, but is stopped when the M / G 26 that rotates the engine 2 is stopped in other processes. It can be applied to produce an effect of suppressing vibration.

  In the third embodiment, when executing step S280 of the engine stop M / G drive process (FIG. 3), the M / G 26 itself is stopped at the timing at which the rotational drive force of the M / G 26 to the engine 2 is extinguished. It was set in the M / G stop processing (FIG. 8). In addition to this, the process of extinguishing the rotational driving force of the M / G 26 with respect to the engine 2 also corresponds to the off process of the electromagnetic clutch 10a in step S240 of the engine stop M / G driving process (FIG. 3). For this reason, the OFF timing of the electromagnetic clutch 10a in step S240 may also be the timing when the angular acceleration of the crankshaft 2a becomes a positive region.

  For example, the processing as shown in the flowchart of FIG. 17 is executed in place of steps S240 to S270 of the engine stop M / G drive processing (FIG. 3), so that the vibration also occurs when the engine rotation is stopped by turning off the electromagnetic clutch 10a. Can be reduced. That is, when there is a drive request for the auxiliary machinery 22 (“YES” in S230), the crank counter CCRNK reaches “0, 4, 8, 12, 16, 20” after Xstop = “ON”. It is determined whether or not (S235). This determination is “YES” once the crank counter CCRNK has any value of “0, 4, 8, 12, 16, 20” after the vibration reduction processing end flag Xstop is set to “ON”. It is determined. Therefore, after Xstop = “ON” is set, this process is temporarily ended as long as the crank counter CCRNK does not become “0, 4, 8, 12, 16, 20”. However, once CCRNK = “0, 4, 8, 12, 16, 20”, “YES” is determined in step S235, and steps S240 to 270 described in the first embodiment are performed. Executed. In such a process, the timing at which the electromagnetic clutch 10a is first turned off in the execution of step S240 is the timing when CCRNK = “0, 4, 8, 12, 16, 20”. Even when the angular acceleration of the shaft 2a is positive, the rotational driving force of the M / G 26 with respect to the engine 2 can be extinguished particularly at the timing when the angular acceleration is almost the maximum. Thus, vibration can be suppressed even when the engine rotation is stopped by turning off the electromagnetic clutch 10a.

  In the fourth embodiment, in the limit rotational speed NEs setting process (FIG. 15), when the vibration intensity is lower than the reference intensity at any frequency (“NO” in S770), the currently set limit The rotational speed NEs is decreased by the decrease correction value NEd as shown in the equation 2 (S780). In addition, when the vibration intensity is less than the reference intensity (“NO” in S770), the value of the limit rotation speed NEs may be maintained without reducing the limit rotation speed NEs.

  Similarly, in the limit rotational speed NEs setting process (FIG. 15), if there is a vibration intensity exceeding the reference intensity (“YES” in S770), the engine speed corresponding to the maximum frequency fmax is expressed by the above formula. As shown in FIG. 3, the limit rotational speed NEs was calculated by performing an increase correction with the increase correction value NEp (S810). In addition to this, by setting a value sufficiently lower than the vibration intensity that gives a sense of incongruity to the vehicle occupant as the reference intensity in step S770, the engine speed itself corresponding to the maximum frequency fmax is set as the limit speed NEs. May be set.

  In the fifth embodiment, in the limit rotational speed NEs setting process (FIG. 16), when the rotation of the crankshaft 2a is stopped while the absolute value of the acceleration remains below the reference value (“YES” in S940). ), The currently set limit rotational speed NEs is decreased by the decrease correction value NEd as shown in the equation 4 (S960). In addition, when the rotation of the crankshaft 2a is stopped without causing a problem vibration, the value of the limit rotation speed NEs may be maintained without reducing the limit rotation speed NEs. .

  Similarly, in the limit rotational speed NEs setting process (FIG. 16), when the absolute value of the acceleration is equal to or higher than the reference value (“YES” in S950), the current engine rotational speed NE is shown in the above equation 5. As described above, the limit rotational speed NEs is calculated by performing the increase correction with the increase correction value NEp (S980). In addition to this, even if the current engine speed NE itself is set as the limit engine speed NEs by setting a value sufficiently lower than a value that gives a sense of incongruity to the vehicle occupant as the reference value in step S950. good.

  The limit rotation speed NEs setting process (FIG. 15) in the fourth embodiment and the limit rotation speed NEs setting process (FIG. 16) in the fifth embodiment are combinations with the configuration of the first embodiment. The limit rotational speed NEs setting process (FIGS. 15 and 16) may be combined with the configurations of the second embodiment and the third embodiment, respectively.

Although the embodiment of the present invention has been described above, it should be noted that the embodiment of the present invention includes the following embodiment.
(1). 9. The internal combustion engine rotation means according to claim 1, wherein the internal combustion engine rotation means is a motor generator disposed outside a driving force transmission system from the internal combustion engine to the wheels. Control device.

1 is a system configuration diagram of an internal combustion engine for a vehicle and a control device thereof according to Embodiment 1. FIG. 5 is a flowchart of automatic stop processing executed by the eco-run ECU according to the first embodiment. 6 is a flowchart of an engine stop M / G drive process executed by the eco-run ECU according to the first embodiment. 4 is a flowchart of crankshaft rotation processing executed by the eco-run ECU according to the first embodiment. 3 is a flowchart of automatic start processing executed by the eco-run ECU according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment. 9 is a flowchart of crankshaft rotation processing executed by an eco-run ECU according to the second embodiment. 10 is a flowchart of M / G stop processing executed by an eco-run ECU according to the third embodiment. Explanatory drawing which shows the relationship between the crank counter CCRNK in Embodiment 3, and the stroke of each cylinder. 10 is a timing chart showing an example of control in the third embodiment. 10 is a timing chart showing a comparative example with respect to the third embodiment. 10 is a graph showing actual measurement data according to the third embodiment. 10 is a graph showing actual measurement data as a comparative example with respect to the third embodiment. FIG. 5 is a comparative distribution diagram of actually measured data between the third embodiment and a comparative example. 10 is a flowchart of limit rotation speed NEs setting processing executed by an eco-run ECU according to the fourth embodiment. 10 is a flowchart of limit rotational speed NEs setting processing executed by an eco-run ECU according to the fifth embodiment. 10 is a flowchart showing a modification of the third embodiment.

Explanation of symbols

  2 ... Engine, 2a ... Crankshaft, 2b ... Intake pipe, 2c ... Surge tank, 4 ... Torque converter, 6 ... Automatic transmission (A / T), 6a ... Output shaft, 10 ... Pulley, 10a ... Electromagnetic clutch, 14 ... Belts 16, 18 ... pulleys, 22 ... auxiliaries, 26 ... motor generator (M / G), 28 ... inverter, 30 ... battery for high voltage power source, 32 ... DC / DC converter, 34 ... battery for low voltage power source, 36 ... starter, 38 ... electric hydraulic pump, 40 ... eco-run ECU, 42 ... fuel injection valve, 44 ... electric motor, 46 ... throttle valve, 48 ... engine ECU, 50 ... VSC-ECU, 52 ... brake pedal, 52a ... brake switch 56 ... Brake booster 56a ... Diaphragm 56b ... First pressure chamber 56c ... Second pressure chamber 56d ... brake booster pressure sensor, 56e ... check valve, 56f ... negative pressure control valve, 56 g ... spring, 56h ... pushrod, 56i ... master cylinder, 56j ... input rod.

Claims (8)

An internal combustion engine operation stop rotation control device that executes internal combustion engine rotation control when the internal combustion engine operation is stopped using an internal combustion engine rotation means capable of rotating the operation stopped internal combustion engine,
In the fully closed state of the throttle valve provided in the intake pipe of the internal combustion engine, the internal combustion engine speed when the internal combustion engine is stopped is maintained at the reference rotational speed by the internal combustion engine rotating means, whereby the cylinder air pressure of the internal combustion engine is maintained. An internal-combustion-engine stop-time rotation control device comprising: an internal-combustion-engine stop-time vibration reducing unit that reduces vibrations when the internal combustion engine stops rotating by reducing the rotation of the internal combustion engine after reducing the internal combustion engine.   2. The internal combustion engine in-cylinder air pressure of the internal combustion engine according to claim 1, wherein the internal combustion engine stop vibration reducing means maintains the internal combustion engine speed at a reference speed for a reference time when the internal combustion engine is stopped. An internal combustion engine operation stop rotation control device that reduces vibrations when the internal combustion engine stops rotating by reducing the rotation of the internal combustion engine after reducing the internal combustion engine.   2. The internal combustion engine stop vibration reducing means according to claim 1, wherein the internal combustion engine stop vibration reducing means maintains the internal combustion engine speed at the reference engine speed when the operation of the internal combustion engine is stopped until the intake pipe pressure reaches the reference intake pressure. An internal combustion engine operation stop rotation control device that reduces vibrations when the internal combustion engine rotation stops by stopping the rotation of the engine.   4. The structure according to claim 1, wherein the internal combustion engine stop vibration reducing means gradually decreases the rotational speed when stopping the rotation of the internal combustion engine from the rotational state of the reference rotational speed. An internal combustion engine operation stop rotation control device.   5. The internal combustion engine stop vibration reducing means according to claim 4, wherein the internal combustion engine stop vibration reducing means immediately stops the rotation of the internal combustion engine being gradually reduced immediately before the resonance rotational speed. Rotation control device.   6. The configuration according to claim 5, further comprising a resonance speed detecting means for detecting a resonance speed of the internal combustion engine, wherein the internal combustion engine stop vibration reducing means is configured so that the speed of the internal combustion engine is equal to the resonance speed detection means. An internal combustion engine operation stop rotation control device that stops the rotation of the internal combustion engine before the detected resonance rotational speed is reduced.   7. The configuration according to claim 6, wherein the resonance rotational speed detection means extracts a resonance frequency from vibration when the internal combustion engine stops rotating, and determines the resonance rotational speed of the internal combustion engine based on the resonance frequency. Rotation control device for internal combustion engine operation stop.   6. The configuration according to claim 5, further comprising resonance state detection means for detecting a resonance state of the internal combustion engine, wherein the internal combustion engine stop vibration reducing means is provided in the resonance state detection means by reducing the rotational speed of the internal combustion engine. An internal combustion engine operation stop rotation control device that stops the rotation of the internal combustion engine before the detected resonance state becomes larger than the reference vibration state.

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