JP4775360B2 - Automatic engine stop device - Google Patents

Description

  The present invention relates to an automatic engine stop device.

  Conventionally, for the purpose of improving fuel economy and emission, the engine is automatically stopped when a predetermined automatic stop condition is satisfied, and when the predetermined restart condition is satisfied during the automatic engine stop, There is known a system for automatically starting an engine, that is, a so-called idle stop (see, for example, Patent Document 1).

In such an idle stop system, if the engine is automatically stopped when the battery has deteriorated, there is a possibility that the starter motor may be hindered and the engine cannot be restarted. Therefore, the automatic stop condition includes a non-deterioration condition that the battery is not deteriorated.
JP 2004-278402 A

  By the way, when the engine is prohibited from being automatically stopped due to the deterioration of the battery, for example, if the deterioration of the battery is resolved by replacing the battery with a new one, for example. In order to improve fuel efficiency and emissions, it is desirable to detect the detection as early as possible and restart the automatic engine stop.

  The present invention has been made in view of this point, and an object of the present invention is to determine, as soon as possible and accurately, the elimination of the deterioration state of the battery in the automatic engine stop device.

  According to one aspect of the present invention, an automatic engine stop device includes an engine, a first battery that is always connected to an electric load mounted on the vehicle and supplies electric power to the electric load, and a starting motor for the engine. A second battery that is always connected and supplies power to the starter motor, a generator that is driven by the engine and supplies generated power to the first and second batteries, the first battery, and the starter A first switching means that is interposed between the motor and the two switches between a connected state and a disconnected state; and is interposed between the second battery and the generator so that they are not connected and disconnected. It includes at least a second switching means for switching to a connected state, a battery deterioration determining means for determining that the second battery has deteriorated, and a non-deteriorating condition in which the second battery has not deteriorated. It said engine when the constant of the stop condition is satisfied with automatically stopping comprises after its automatic stop, and control means in which a predetermined starting condition is to restart the engine when satisfied, the.

  Further, when the engine is started based on the ignition operation of the occupant, the control means places the first battery and the starter motor in a connected state by the first switching means, and from both the first and second batteries, When power is supplied to the starting motor while the second battery is determined to be deteriorated by the battery deterioration determining means, the first switching means uses the first switching means when starting the engine based on the ignition operation. 1 The connection between the battery and the starter motor is prohibited, power is supplied from only the second battery to the starter motor, and the accompanying voltage drop of the second battery is detected to eliminate the deterioration state of the second battery. And after the detection, the first switching means connects the first battery and the starting motor. In the state, to start the engine by to supply power to the starter motor from both the first and second battery.

  This configuration is a so-called two-battery system including a first battery and a second battery. The first battery is a battery that mainly supplies power to an electric load, and the second battery is a battery that supplies power to a starter motor.

  In this configuration, when the engine is started based on the ignition operation of the occupant, the first battery and the starting motor are connected by the first switching means, and power is supplied from both the first and second batteries to the starting motor. To start the engine.

  Here, if an attempt is made to determine as soon as possible that the above-described degradation state of the battery has been eliminated, it is desirable to determine when starting the engine based on the ignition operation. However, when starting the engine based on the ignition operation, the first switching means connects the first battery and the starter motor to supply power to the starter motor from both the first and second batteries. The battery state (for example, the degree of voltage drop) cannot be accurately determined.

  Therefore, in the above configuration, when it is determined by the battery deterioration determination means that the second battery has deteriorated, the connection between the first battery and the starter motor by the first switching means is temporarily prohibited, and the second battery Only supply power to the starting motor. As a result, the degree of voltage drop of the second battery can be accurately detected, and it is possible to determine whether or not the deterioration state of the second battery has been eliminated based on this. Therefore, it can be determined as early as possible with high accuracy whether or not the deterioration state of the second battery has been eliminated. This means that the automatic stop of the engine is restarted at an early stage, so that fuel efficiency and emission are improved.

  Then, when the detection of the voltage drop degree of the second battery is completed, the first battery and the starting motor are connected by the first switching means, and power is supplied from both the first and second batteries to the starting motor. By doing so, it is possible to reliably start the engine.

  Thus, in this configuration, since only the power from the second battery is supplied to the starter motor at the start of the engine start, the startability of the engine is reduced accordingly. However, the decrease in the startability is limited when it is determined that the second battery is deteriorated, and the phenomenon that the startability is decreased is caused to cause the occupant to recognize the deterioration of the battery. Can be encouraged to replace the battery.

When the temperature of the second battery is lower than a predetermined value, the control means is configured to start the engine based on the ignition operation even when the battery deterioration determination means determines that the second battery is deteriorated. In this case, it is preferable that the first battery and the starter motor are connected to each other by the first switching unit, and power is supplied to the starter motor from both the first and second batteries.

  In other words, when the engine startability is reduced, it is preferable to supply both the first and second battery power to the starter motor from the beginning in order to avoid further deterioration of the startability.

  In addition, it is preferable that the control unit performs correction according to the temperature of the second battery when determining the deterioration elimination of the second battery. Since the degree of battery voltage drop varies according to the battery temperature, whether or not the deterioration state of the second battery has been eliminated by detecting the degree of voltage drop of the second battery more accurately by performing temperature correction. The determination accuracy becomes even higher.

  As described above, according to the present invention, when the deterioration of the second battery is determined, power is supplied from the second battery only to the starting motor when the engine is started based on the ignition operation. By detecting the degree of voltage drop of the second battery, it is possible to determine whether or not the deterioration state of the second battery has been eliminated as quickly and accurately as possible. Thereby, when the deterioration state of the second battery is resolved, the automatic engine stop can be restarted at an early stage, and fuel consumption and emission can be further improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

-Schematic configuration of idle stop system-
1 and 2 show an embodiment of an idle stop system including an engine automatic stop device according to this embodiment. The system E includes an engine 1 including a cylinder head 10 and a cylinder block 11 and an ECU 2 (engine controller) for controlling the engine 1. As shown in FIG. 2, the engine 1 is provided with four cylinders 12A to 12D. Inside each of the cylinders 12A to 12D, pistons connected to the crankshaft 3 as shown in FIG. Thus, a combustion chamber 14 is formed above the piston 13 in each of the cylinders 12A to 12D.

  Here, in general, in a multi-cylinder four-cycle engine, each cylinder performs a combustion cycle composed of intake, compression, expansion, and exhaust strokes with a predetermined phase difference. In the case of a cylinder engine, when referred to as the first cylinder 12A, the second cylinder 12B, the third cylinder 12C, and the fourth cylinder 12D from one end in the cylinder row direction, the first cylinder (# 1), the third cylinder (# 3), Combustion is performed with a phase difference of 180 degrees in crank angle in the order of the fourth cylinder (# 4) and the second cylinder (# 2). Thus, the output torque accompanying the drive of the engine 1 is transmitted to drive wheels (not shown) via a torque converter connected to the crankshaft 3 and an automatic transmission (AT) 52 (see FIG. 3). become.

  A spark plug 15 for igniting and burning the air-fuel mixture in the combustion chamber 14 is provided at the top of each combustion chamber 14 of each of the cylinders 12A to 12D. An electrode is disposed so as to face the combustion chamber 14. Further, a fuel injection valve 16 is disposed on the side of the combustion chamber 14 (right direction in FIG. 1) with the tip injection hole facing the combustion chamber 14. This fuel injection valve 16 incorporates a needle valve and a solenoid (not shown) and is driven to open for a time corresponding to the pulse width in response to the input of a pulse signal from the ECU 2 so that an amount of fuel corresponding to the driving time is supplied. The cylinders 12A to 12D are configured to inject directly. The fuel injection direction is adjusted so as to be directed to the vicinity of the electrode of the spark plug 15.

  Although not shown, fuel is supplied to the fuel injection valve 16 via a fuel supply passage or the like by a fuel pump, and the fuel supply pressure is in the middle of the compression stroke of each cylinder 12A to 12D. Thereafter, the pressure is set higher than the pressure in the combustion chamber 14 so that fuel can be injected into the high-pressure in-cylinder combustion chamber 14.

  An intake port 17 and an exhaust port 18 that open toward the combustion chamber 14 are provided in the upper part of the combustion chamber 14 of each of the cylinders 12A to 12D. An intake valve 19 and an exhaust valve are provided in these ports 17 and 18, respectively. 20 are arranged respectively. These intake valve 19 and exhaust valve 20 are driven by a valve operating mechanism including a camshaft (not shown), and as described above, each of the cylinders 12A to 12D performs a combustion cycle with a predetermined phase difference. The opening / closing timing of the intake / exhaust valves 19 and 20 for each cylinder is set.

  Further, an intake passage 21 and an exhaust passage 22 are provided so as to communicate with the intake port 17 and the exhaust port 18, respectively. As shown in FIG. An independent branch intake passage 21a is provided for each of the cylinders 12A to 12D, and the upstream end of each branch intake passage 21a communicates with the surge tank 21b. The intake passage 21 upstream of the surge tank 21b is a common intake passage 21c common to the cylinders 12A to 12D. The throttle valve 23 adjusts the cross-sectional area of the passage 21c by, for example, a butterfly valve to restrict the intake flow. And an actuator 24 for driving it, and as shown only in FIG. 2, an air flow sensor 25 for detecting the intake air amount is provided upstream of the throttle valve 23.

  On the other hand, a catalyst 29 for purifying the exhaust is disposed downstream of the collection portion of the exhaust passage 22 where exhaust from the cylinders 12A to 12D collects. The catalyst 29 may be a so-called three-way catalyst, but is not limited thereto, and may be a so-called lean NOx catalyst, for example.

  Further, the engine 1 is provided with an alternator 28 that is drivingly connected to the crankshaft 3 by a belt or the like, and the electric power generated by the alternator 28 is stored in a battery 80 as shown in FIG. It has become.

  Further, the engine system E is provided with two crank angle sensors 30 and 31 for detecting the rotation angle of the crankshaft 3, and the engine rotation speed is mainly based on a signal from one crank angle sensor 30. The rotation direction and the rotation angle of the crankshaft 3 are detected from the crank angle signals output from the two crank angle sensors 30 and 31 with the phases shifted from each other. In addition, the engine system E includes a cam angle sensor 32 that detects a specific rotational position of the camshaft and outputs it as a cylinder identification signal, and an ignition switch 33 that performs an on / off operation for manually switching between operation and stop of the engine 1. (IG switch), a vehicle speed sensor 34 comprising an electromagnetic pickup for detecting the vehicle speed, a brake fluid pressure sensor 35 for detecting the brake fluid pressure, and the like are provided.

  The ECU 2 receives signals from the sensors and the switches 25, 30 to 35, and outputs a signal for controlling the fuel injection amount and the injection timing to the fuel injection valve 16, and an ignition device for the ignition plug 15. 27 outputs a signal for controlling the ignition timing, and further outputs a signal for controlling the throttle opening to the actuator 24 of the throttle valve 23. As will be described in detail below, the ECU 2 stops the fuel supply to each cylinder 12A to 12D (fuel cut) and automatically stops the engine when a predetermined engine stop condition is satisfied during idling. Thereafter, the engine 1 is automatically restarted when a predetermined engine restart condition is satisfied by the driver's brake operation or the like.

  Here, the engine 1 according to the present embodiment is capable of starting the engine 1 by itself without borrowing the force of a starting motor 54 to be described later when the engine 1 is restarted. That is, first, the first combustion is performed in the cylinder 12 in which the piston 13 is stopped in the middle of the compression stroke, and the piston 13 is pushed down, so that the crankshaft 3 is slightly reversed, thereby being in the expansion stroke. The piston 13 of the cylinder 12 is raised and the air-fuel mixture in the cylinder 12 is compressed. Then, by igniting and burning the air-fuel mixture in the expansion stroke cylinder 12 that has been compressed in this manner and whose temperature and pressure have been increased, a torque in the forward rotation direction is applied to the crankshaft 3, and the engine 1 is The engine is started (so-called combustion start).

  In order to start the engine 1 by itself, the torque in the forward rotation direction is applied to the crankshaft 3 as much as possible by the combustion of the cylinder 12 in the expansion stroke at the time of stop. , Abbreviated as TDC), the cylinder 12 must overcome its compression reaction force (compression pressure) and exceed TDC. Therefore, in order to start the engine 1 reliably, it is necessary to ensure sufficient air for combustion in the stop-time expansion stroke cylinder 12.

  At the same time, in order to improve the startability of the engine, it is necessary to keep the stop position of the piston 13 of the cylinder 12 in the expansion stroke within a predetermined range suitable for restart.

  Therefore, as described later, the engine 1 adjusts the amount of intake air into the compression stroke cylinder 12 and the expansion stroke cylinder 12 at the time of stop by adjusting the opening of the throttle valve 23, or the alternator 28, as will be described later. The external load of the engine 1 is adjusted by adjusting the power generation amount.

  However, even if such control at the time of automatic stop is performed, the stop position of the piston 13 of the cylinder 12 in the expansion stroke may not fall within a predetermined range due to various factors. It is desirable to start the engine 1 with the starter motor 54 without restarting the engine 1.

  The engine 1 is started when the engine 1 is started for the first time (that is, when the engine 1 is started by an ignition operation) or when the engine 1 cannot be restarted by the combustion start described above. For this purpose, a starting motor 54 is provided. The starter motor 54 includes a pinion gear that meshes with a ring gear 55 that is fixed to the crankshaft 3. The pinion gear can be reciprocated between a meshing position that meshes with the ring gear and a retracted position that is distant from the ring gear. ing. When the engine 1 is restarted by the starter motor 54, the crankshaft 3 is rotationally driven, that is, cranked by moving the pinion gear and meshing with the ring gear 55 and driving the starter motor 54 according to control by the ECU 2. Will do.

  FIG. 3 shows a configuration of a power supply system according to the idle stop system, and this system is a two-battery system including two batteries of a main battery 80a and a sub battery 80b.

  The main battery 80a is a battery having a relatively large capacity. The main battery 80a is always connected to the vehicle electrical load 82 and mainly supplies power to them. The vehicle electrical load 82 is roughly divided into a first load group 82a, a second load group 82b, and a third load group 82c.

  The first load group 82a is an electric load among the general electric loads in which it is not desirable for the battery voltage to temporarily decrease during cranking by the starter motor 54. Specific examples include an airbag control unit, an EHPAS (electrohydraulic power steering) control unit, a navigation system, audio, and various meters.

  The second load group 82b is a general electric load that does not cause much problem even when the battery voltage temporarily decreases during cranking by the starter motor 54. Specific examples include various lights and defoggers.

  The third load group 82c is an electric load peculiar to the vehicle, and specifically includes a hill holder mechanism that prevents the vehicle from sliding down while stopping on a slope, a motor of an electric power steering, and the like. The hill holder mechanism covers that the power brake does not operate during the automatic stop of the engine 1, and the electric power steering covers that the EHPAS does not operate during the automatic stop of the engine 1.

  The main battery 80a is also connected to the starting motor 54 via the power relay 85. The power relay 85 is turned on and off by the ECU 2. When the power relay 85 is off, power is not supplied from the main battery 80a to the starter motor 54, and when the power relay 85 is on, power can be supplied from the main battery 80a to the starter motor 54. Thus, the power relay 85 functions as a first switching unit that switches between supplying power to the starting motor 54 from the main battery 80a and stopping the supply.

  Further, the main battery 80a is always connected to the alternator 28, whereby the electric power generated by the alternator 28 is stored in the main battery 80a.

  The sub-battery 80b is a battery having a relatively small capacity, and is a battery dedicated to driving the starter motor 54 here. The sub-battery 80b is always connected to the starter motor 54, and power can be supplied to the starter motor 54. The sub battery 80b is also connected to the alternator 28 (main battery 80a) via the charge relay 87. On / off of the charge relay 87 is controlled by the ECU 2. When the charge relay 87 is on, the electric power generated by the alternator 28 is also stored in the sub battery 80b. In this manner, the charge relay 87 functions as a second switching unit that switches between supply of generated power from the alternator 28 to the sub battery 80b and stop of the supply.

  As described above, when the engine 1 cannot be restarted due to combustion start, the engine 1 is started by cranking by the starter motor 54. At this time, the power relay 85 is turned off, whereby electric power is supplied from the sub-battery 80b to the starter motor 54, and the starter motor 54 is driven. Since the power consumption of the starter motor 54 at the time of cranking is relatively large, the battery voltage of the sub battery 80b is temporarily greatly reduced. However, the vehicle electrical load 82 receives power supply from the main battery 80a and is not affected by the voltage drop of the sub battery 80b. This is particularly effective in preventing a voltage drop for the first load group 82a and the third load group 82c, in which a battery voltage drop is not desirable.

  Furthermore, when starting the engine 1 by operating the IG switch 33, as will be described later, basically, by turning on the power relay 85, both the sub-battery 80b and the main battery 80a are connected to the starting motor 54. Power is supplied.

  Then, after starting the engine 1 with the electric power of the sub battery 80b, the sub battery 80b is charged by turning on the charge relay 87.

  The main battery 80a and the sub-battery 80b are respectively connected to the ECU 2. The ECU 2 uses the battery voltages of the main battery 80a and the sub-battery 80b and the detected values of SOC (State of Charge), respectively. The deterioration state (whether or not it is deteriorated) is determined at any time. When it is determined that the sub battery 80b has deteriorated, the ECU 2 turns on the sub battery deterioration flag. As will be described later, the sub-battery deterioration flag is used for the automatic stop control of the engine 1 and the control when the engine 1 is started.

−Automatic engine stop / start control−
Next, the automatic stop control of the engine 1 executed by the ECU 2 will be described with reference to the flowchart shown in FIG.

  First, in step S11, it is determined whether or not the vehicle speed is 0 km / h based on the detected value of the vehicle speed sensor 34. If the vehicle speed is not 0 km / h, step S11 is repeated while the vehicle speed is 0. If YES, the process proceeds to step S12.

  In step S12, it is determined whether or not an idle stop condition (an automatic engine stop condition) is satisfied. Specifically, the automatic stop condition includes a condition that the detected brake fluid pressure is equal to or higher than a predetermined threshold based on the detected value of the brake fluid pressure sensor 35 in addition to the accelerator being off and the brake being on. included. Further, as described above, a condition (non-deterioration condition) that the sub-battery deterioration flag that is set when the sub-battery 80b is deteriorated is included. This is because if the engine 1 is stopped while the sub battery 80b is deteriorated, the engine 1 may not be restarted by the power from the sub battery 80b.

  If the automatic stop condition is not satisfied, step S12 is repeated. If the automatic stop condition is satisfied, the process proceeds to step S13.

  In step S13, stop control of the engine 1 is executed. The stop control of the engine 1 is control for keeping the piston position within a predetermined range optimum for combustion start. Specifically, the stop compression stroke cylinder 12 and the expansion stroke by adjusting the opening of the throttle valve 23 are controlled. The amount of intake air into the cylinder 12 is adjusted, and the external load of the engine 1 is adjusted by adjusting the power generation amount of the alternator 28. Thereby, the rotational speed of the engine 1 is adjusted, and the engine 1 is stopped so that the piston 13 is within a predetermined stop range. In this way, the engine 1 is automatically stopped.

  Next, the restart control of the engine 1 executed by the ECU 2 will be described with reference to the flowchart shown in FIG.

  First, in step S21, it is determined whether a restart condition is satisfied. For example, when the driver tries to start the vehicle by returning the brake pedal based on the detection value of the brake fluid pressure sensor 35, the restart condition is established. When the restart condition is not satisfied, step S21 is repeated. When the restart condition is satisfied, the process proceeds to step S22.

  In step S22, based on the stop position of the piston 13, it is determined whether or not the piston stop position is within a predetermined range where combustion start is possible. On the other hand, if NO in step S24, the process proceeds to step S24.

  In step S23, as described above, the engine 1 is restarted by combustion start, while in step S24 in which combustion start is impossible, the starter motor 54 is driven only by power supply from the sub battery 80b, and cranking is performed. The engine 1 is restarted.

  Next, control when starting the engine 1 based on the ignition operation will be described with reference to FIG. In this control, when it is determined that the sub-battery 80b has deteriorated, it is determined whether or not the deterioration state of the sub-battery 80b has been eliminated when the engine 1 is started.

  First, in step S31 after the start, it is determined whether or not the ECU 2 is activated. When the ECU 2 is not activated, NO is repeated, and when the ECU 2 is activated, the process proceeds to step S32. .

  In step S32, it is determined whether or not the IG switch 33 is turned on. If the answer is NO, the process repeats step S32. If the answer is YES, the process proceeds to step S33.

  In step S33, it is determined whether or not the sub-battery deterioration flag is on. If the sub-battery deterioration flag is not on (NO in the sub-battery 80b), the process proceeds to step S34 and the power relay 85 is turned on. On the other hand, the process proceeds to step S35. On the other hand, if the sub battery deterioration flag is ON (it is determined that the sub battery 80b is deteriorated), the process proceeds to step S34 without proceeding to step S34. The process proceeds to S35.

  In step S35, it is determined whether or not the position of the IG switch 33 is “starter”. If the starter is NO, step S35 is repeated, and if the starter is YES, the process proceeds to step S36.

  In step S36, the starting motor 54 is driven. At this time, when the sub-battery deterioration flag is not on, the power relay 85 is on, so that power is supplied to the starter motor 54 from the main and sub batteries 80a and 80b. Driven. On the other hand, when the sub-battery deterioration flag is on, the power relay 85 is not turned on, so that power is supplied from only the sub-battery 80b to the starter motor 54, thereby driving the starter motor 54.

  Then, in the following step S37, it is determined whether or not the sub-battery deterioration flag is on. If the sub-battery deterioration flag is on, the process proceeds to step S38. The process proceeds to step S313 without passing through the deterioration elimination determination of the sub battery 80b in S38 to S312.

In step S38, the engine speed, the battery voltage, and the battery fluid temperature are detected, and the state of the sub battery 80b is calculated based on the detected engine speed. That is, the relationship between the consumption current of the sub-battery 80b accompanying the driving of the starter motor 54 and the battery voltage is detected. Specifically, as shown in FIG. 7, the back electromotive force of the starter motor corresponding to the detected engine speed is calculated based on a map or calculation formula stored in advance in the ECU. Then, based on the back electromotive force, the battery voltage, and the preset resistance value of the starting motor 54,
The current value of the sub battery 80b is calculated from the current value = (battery voltage−back electromotive force) / resistance value of the starting motor.

  In step S39, it is determined whether or not the detection of the state of the sub battery 80b has been completed. If NO, the process returns to step S38, and the detection of the state of the sub battery 80b is continued. The process proceeds to step S310.

  In step S310, as shown in FIG. 8, the battery voltage value with respect to the consumption current of the sub-battery 80b (see the white circle in FIG. 8) and the voltage drop degree in the new battery preset and stored in the ECU 2 (same as above). (See the solid line in the figure: evaluation index), and based on the size of the gap (difference in voltage value, see arrow in the figure), whether the deterioration state of the sub-battery 80b has been eliminated, that is, the sub-battery It is determined whether or not 80b has been replaced. That is, when the size of the gap is smaller than the predetermined value, it can be determined that the sub battery 80b has been replaced.

  Here, since the degree of voltage drop of the battery varies depending on the temperature of the battery, the evaluation index is corrected (inclination correction) according to the detected liquid temperature of the sub-battery 80b, for example, using a correction coefficient or a map. You may be made to do by.

  When it is determined in step S310 that the sub-battery 80b is new (YES), the process proceeds to step S311 and the sub-battery deterioration flag is cleared (flag is turned off), and then the process proceeds to step S312. When it is determined that the sub battery 80b is not new (NO), the process proceeds to step S312 without proceeding to step S311.

  In step S312, the power relay 85 is turned on, whereby electric power is supplied to the starter motor 54 from both the main battery 80a and the sub battery 80b. Then, in the following step S313, it is determined whether or not the IG switch 33 is turned back on from the starter. When the IG switch 33 is not turned back on (not on), step S3313 is repeated to start the motor 54. When the IG switch 33 returns to ON (that is, the engine 1 has started), the process proceeds to step S314. In step S314, the power relay 85 is turned off and the flow ends.

  After the sub-battery deterioration flag is turned off in this way, the non-deterioration condition included in the automatic stop condition of the engine 1 is satisfied, so that the engine 1 can be automatically stopped (see FIG. 4).

  As described above, in the idle stop system, when the sub battery 80b is deteriorated, the automatic stop of the engine 1 is prohibited, while the sub battery 80b is replaced when the engine 1 is started based on the ignition operation. It can be determined as early as possible that the deterioration state of the sub-battery 80b has been eliminated by determining whether or not it has been performed. Thereby, the automatic stop of the engine 1 which has been prohibited due to the deterioration of the sub-battery 80b can be restarted at an early stage, which is advantageous in improving fuel consumption and emission.

  Further, the determination relating to the battery replacement is made based on the fact that the power supply from the main battery 80a to the starter motor 54 is temporarily prohibited and the power is supplied to the starter motor 54 only from the sub battery 80b. Thus, the state of the sub battery 80b (the degree of voltage drop of the sub battery 80b accompanying the driving of the starter motor 54) can be determined with high accuracy, and the determination accuracy that the deterioration state of the sub battery 80b has been eliminated can be increased. it can. Thus, the automatic stop control of the engine 1 can be properly restarted.

  Further, by supplying power to the starter motor 54 only from the sub battery 80b in this way, the startability of the engine 1 is reduced by that amount, which is determined that the sub battery 80b has deteriorated. In addition, the phenomenon that the startability is deteriorated occurs, and it can be expected that the occupant recognizes the deterioration of the battery and prompts the replacement of the battery.

  Further, in the deterioration elimination determination of the sub battery 80b, since the evaluation index is corrected according to the liquid temperature (battery temperature) of the sub battery 80b, it is more accurately determined whether or not the sub battery 80b has been replaced with a new one. It is possible to avoid erroneous determination.

  In the starting control flow of the engine 1 based on the ignition operation, as shown in FIG. 9, whether or not the battery liquid temperature (battery temperature) is higher than a predetermined value between step S33 and step S35. A step of determining (Step S315) may be added. In other words, when the battery temperature is higher than the predetermined value, the process proceeds to step S35, and the starting motor 54 is driven by the electric power of only the sub battery 80b. On the other hand, when the battery temperature is equal to or lower than the predetermined value, the process proceeds to step S34. 85 may be turned on, thereby prohibiting power supply only from the sub-battery 80b. This is control in consideration of the startability of the engine 1. That is, when the battery temperature is relatively low and the startability of the engine 1 is poor, even if it is determined that the sub-battery 80b is deteriorated, the deterioration elimination determination of the sub-battery 80b is not performed. In this way, further deterioration of the startability of the engine 1 may be avoided. In step S315, based on the engine water temperature instead of the battery liquid temperature, when the engine water temperature is higher than a predetermined value, the process proceeds to step S35, and the starter motor 54 is driven by the electric power of only the sub battery 80b. When the engine water temperature is equal to or lower than the predetermined value, the process may proceed to step S34 to turn on the power relay 85, thereby prohibiting the power supply from only the sub battery 80b.

  The engine 1 is configured to be able to start combustion. However, the present invention is not limited to this. For example, the engine 1 may be configured only to be started by the starter motor 54.

  As described above, the present invention is useful as an automatic engine stop device because it can improve fuel efficiency and emission by detecting early that the deterioration state of the battery has been eliminated.

1 is a schematic configuration diagram of an idle stop system according to an embodiment of the present invention. It is a schematic diagram which shows the structure of the intake system and exhaust system of an engine. It is a schematic block diagram of the electric power supply system which concerns on an idle stop system. It is a flowchart which shows the control which concerns on an engine automatic stop. It is a flowchart which shows the control which concerns on restart of an engine. It is a flowchart which shows the control which concerns on starting of the engine based on ignition operation. It is a figure which shows the relationship of the back electromotive force with respect to the engine speed in a starting motor. It is a figure explaining the standard of battery degradation cancellation determination. It is a flowchart which shows a part of engine starting control which concerns on a modification.

Explanation of symbols

1 Engine 2 ECU (control means, battery deterioration determination means)
28 Alternator (generator)
33 IG switch 54 Start motor 80a Main battery (first battery)
80b Sub battery (second battery)
82 Vehicle electrical load 85 Power relay (first switching means)
87 Charge relay (second switching means)

Claims (3)

Engine,
A first battery that is always connected to an electric load mounted on the vehicle and supplies electric power to the electric load;
A second battery that is always connected to the starter motor of the engine and supplies power to the starter motor;
A generator driven by the engine and supplying generated power to the first and second batteries;
A first switching means interposed between the first battery and the starter motor, for switching between a connected state and a disconnected state;
A second switching means interposed between the second battery and the generator to switch both between a connected state and a disconnected state;
Battery deterioration determining means for determining that the second battery is deteriorated;
The engine is automatically stopped when a predetermined stop condition including at least a non-deteriorating condition in which the second battery has not deteriorated, and after the automatic stop, the engine is restarted when a predetermined start condition is satisfied. Control means for starting,
The control means further includes
When starting the engine based on the ignition operation of the occupant, the first battery and the starting motor are connected by the first switching means, and power is supplied to the starting motor from both the first and second batteries. While letting
When it is determined by the battery deterioration determining means that the second battery has deteriorated, when the engine is started based on the ignition operation, the first switching means connects the first battery and the starter motor. Prohibiting, supplying power to the starting motor only from the second battery, detecting a voltage drop degree of the second battery associated therewith to determine whether or not the deterioration state of the second battery has been eliminated, and After the detection, the first switching means connects the first battery and the starter motor and supplies power to the starter motor from both the first and second batteries to start the engine. Automatic stop device. The automatic engine stop device according to claim 1,
When the temperature of the second battery is lower than a predetermined value, the control means is configured to start the engine based on the ignition operation even when the battery deterioration determination means determines that the second battery is deteriorated. In this case, the engine automatic stop device is configured to connect the first battery and the starter motor to the connected state by the first switching unit and to supply power to the starter motor from both the first and second batteries.
The automatic engine stop device according to claim 1,
The control unit is an automatic engine stop device that performs correction in accordance with the temperature of the second battery when determining whether or not the second battery has deteriorated.

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