JP2008014241A - Engine automatically stopping controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine automatically stopping controller by which an idling stopping chance or term can be ensured to the maximum extent possible without inducing malfunction in engine restarting. <P>SOLUTION: A control unit including the engine automatically stopping controller stops an engine under the condition for stopping idling, while restarts the engine (S9) under the conditions for restarting the engine (S8). The condition for stopping idling is defined as the depth of discharge of a battery which exceeds a limit value during an engine stop. Further, idling stopped frequencies are calculated and the limit value for the depth of discharge of a battery is defined as a small value when the idling stopped frequencies are large, while the limit value is defined as a large value when the idling stopped frequencies is small. As a result, the idling stopping chance or term can be ensured to the maximum extent possible with the battery degradation restrained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention automatically stops an engine when a predetermined engine stop condition is satisfied, and restarts the engine when a predetermined engine restart condition is satisfied after the engine is stopped. The present invention relates to an automatic stop control device.

  In general, when a vehicle is temporarily stopped due to a red light or the like, the engine rotates in an idling state, but such idling reduces the fuel efficiency of the vehicle and generates carbon dioxide that contributes to global warming. Increase the amount. Therefore, in recent years, the engine is automatically stopped when a predetermined condition is satisfied when the vehicle is temporarily stopped or idling, and the engine is automatically restarted when the vehicle starts or when the accelerator pedal is depressed, so-called idle An engine (hereinafter referred to as an “idle stop engine”) that improves fuel efficiency and reduces the amount of carbon dioxide produced by performing a stop is used.

In such an idle stop engine, the alternator stops at the time of idle stop, so that electric power is supplied to various electric loads of the automobile exclusively by discharging the battery. For this reason, depending on the state of charge of the battery at the time of idling stop or the power consumption state of the electric load, the engine may not be restarted quickly or smoothly. In order to avoid such problems, when the current consumption value of the electrical load exceeds a predetermined value or when the battery current consumption integrated value exceeds a predetermined value, execution of idle stop is prohibited, and idle stop is already being executed. If any, an idle stop engine or a control device thereof has been proposed in which the idle stop is canceled and the engine is forcibly restarted to recover the battery charge state (see Patent Document 1).
JP 2001-173480 A (paragraphs [0029] to [0031], FIG. 2)

  However, when the idle stop is prohibited or forcibly canceled based on the current consumption value of the electrical load or the battery current consumption integrated value as described above, the above-mentioned problems (such as battery exhaustion) at the time of restarting the engine are solved. However, since the opportunity or period for executing the idle stop is considerably reduced, there is a problem that improvement in fuel consumption performance and reduction in carbon dioxide production cannot be realized sufficiently.

  In general, a lead-acid battery is used as a battery for automobiles. However, when the lead-acid battery is repeatedly charged and discharged, it gradually deteriorates due to sulfation or the like, and its power supply capacity decreases. And the aspect of deterioration of such a lead storage battery is largely different depending on the aspect of charge / discharge particularly related to idle stop. However, the conventional idle stop engine disclosed in Patent Document 1 does not consider such a difference in charging / discharging or deterioration of the battery, so that there is a problem that the deterioration of the battery cannot be sufficiently suppressed. is there.

  The present invention has been made to solve the above-described conventional problems, and can effectively suppress the deterioration of the battery caused by the idle stop, and the engine restarts from the idle stop state. It is an object of the present invention to provide an engine automatic stop control device that makes it possible to secure an opportunity or period for executing idle stop without causing occurrence of the engine.

  An automatic engine stop control device according to the present invention, which has been made to solve the above-mentioned problems, automatically stops the engine when a predetermined engine stop condition is satisfied, and performs a predetermined engine restart after the engine is stopped. An automatic stop / restart control means is provided for restarting the engine when the condition is satisfied. Here, one of the engine restart conditions is that the discharge depth of the battery becomes equal to or greater than a predetermined discharge depth limit value (maximum discharge depth) while the engine is stopped. Further, the engine automatic stop control device includes a stop frequency detecting means for detecting the frequency of engine stop by the automatic stop / restart control means, and a discharge depth limit value when the stop frequency detected by the stop frequency detecting means is large. Discharge depth limit value setting means for setting the discharge depth limit value to a large value when the stop frequency is small while setting the value to be small.

  In the engine automatic stop control device according to the present invention, it is preferable that the discharge depth limit value setting means gradually changes the discharge depth limit value with respect to a change in the stop frequency. The stop frequency detecting means preferably detects the engine stop frequency every predetermined period while the vehicle equipped with the engine is running.

  In the engine automatic stop control device according to the present invention, when the automobile is used in an environment where the idle stop frequency (stop frequency) is large, for example, when used mainly in an urban area, that is, the battery is deteriorated due to the idle stop. Since the depth of discharge limit value is small when the battery is in an environment where it is easy to proceed, battery deterioration due to idle stop can be effectively suppressed. Further, the engine can be restarted quickly and smoothly from the idle stop state.

  On the other hand, when the vehicle is used in an environment where the idle stop frequency is low, for example, when used mainly in a suburb or in a depopulated area, that is, when the battery is not easily deteriorated due to the idle stop, the depth of discharge is reduced. Since the limit value becomes large, it is possible to increase the number of opportunities for executing the idle stop as long as possible without causing any trouble in restarting the engine from the idle stop state, or the period for performing the idle stop as long as possible. be able to.

  In other words, according to the present invention, it is possible to suppress the deterioration of the battery due to the idle stop, and the opportunity or period for executing the idle stop without causing any trouble in restarting the engine from the idle stop state. Can be sufficiently ensured, fuel efficiency can be improved, and the amount of carbon dioxide produced can be reduced.

  In the engine automatic stop control device according to the present invention, when the discharge depth limit value setting means gradually changes the discharge depth limit value with respect to the change of the stop frequency, It is possible to eliminate or suppress the discomfort of the occupant due to the opportunity to execute the stop or the period changing rapidly. In addition, when the stop frequency detection means is adapted to detect the engine stop frequency every predetermined period while the vehicle is running, the discharge depth limit value can be set according to the latest change in the running environment, The opportunity or period for executing the idle stop can be ensured to the maximum while effectively suppressing the deterioration of the battery.

Hereinafter, embodiments of the present invention (best mode for carrying out the present invention) will be described in detail with reference to the accompanying drawings.
As shown in FIG. 1, the engine 1 is not shown in detail, but the fuel is injected from the fuel injection valve 2 into the air in the intake passage (not shown) or the air in the combustion chamber (not shown). (For example, gasoline) is injected to generate an air-fuel mixture, and the air-fuel mixture is ignited and burned by a spark plug 3 in the combustion chamber, and the heat energy generated by the combustion of the air-fuel mixture is converted into rotational movement of the crankshaft 4. It is supposed to convert. The engine 1 is controlled by a control unit C including a computer, as will be described later. In this embodiment, the engine 1 is an ignition engine, but the present invention can be applied to an engine other than the ignition engine, for example, a diesel engine.

  The engine 1 is provided with an alternator 7 (generator) for supplying electric power to the engine 1 or various electric loads 5 of an automobile equipped with the engine 1 and charging the battery 6 with surplus electric power. A V-belt 11 is wound around a drive pulley 8 attached to the front end portion (the left end portion in FIG. 1) of the crankshaft 4 and a driven pulley 10 attached to the front end portion of the rotating shaft 9 of the alternator 7. 7 is driven to rotate by the crankshaft 4 to generate electric power. Further, the engine 1 is provided with a starter 12 (starter motor) for starting the engine 1. Although not shown in detail, the starter 12 rotates when a starter switch (not shown) is turned on and power is supplied from the battery 6, and the crankshaft 4 is connected via a gear set (not shown) or the like. Is rotated to start the engine 1.

  The battery 6 is a lead storage battery, and its positive electrode 6 a is electrically connected to various electric loads 5, an alternator 7, a starter 12, a control unit C and the like by a positive conductor 13. Here, a first current sensor 14 that detects the value of the current (generated current) output from the alternator 7 and the value of the current that is supplied to the electric load 5 (current consumption) are detected on the plus-side conductor 13. A second current sensor 15 is provided. Further, the negative electrode 6 b of the battery 6 is electrically connected to the ground portion 17 (for example, a frame of the vehicle body) by a negative-side conductive wire 16. The battery 6 is provided with a voltage sensor 18 for detecting the output voltage (battery voltage).

  The control unit C is a comprehensive control device for the engine 1 including a computer, and the output current of the alternator 7 detected by the first current sensor 14 and the consumption of the electric load 5 detected by the second current sensor 15. Current, battery voltage detected by the voltage sensor 18 (output voltage of the battery 6), vehicle speed detected by the vehicle speed sensor 20, accelerator opening detected by the accelerator opening sensor 21, and brake detected by the brake switch 22. Various engine controls including idle stop control are performed using on / off or the like as control information.

  However, engine control other than idle stop control, for example, general engine control such as fuel injection control, ignition timing control, and EGR control is well known to those skilled in the art, and such general engine control is described in the present invention. Therefore, only the idle stop control according to the gist of the present invention will be described with reference to the flowchart shown in FIG.

  As shown in FIG. 2, when the idle stop control according to the present invention is started, first, in step S1, the output current of the alternator 7, the current consumption of the electric load 5, the battery voltage, the vehicle speed, the accelerator opening, the brake on -Control information (various signals) such as OFF is read. In step S1, a battery charge state (SOC: State of Charge), a battery deterioration state (SOH: State of Health), a battery discharge depth, and the like are calculated based on the control information. Subsequently, in step S2, it is determined whether or not idle stop is already being executed. Here, if the idle stop is being executed (YES), the following steps S3 to S7 are skipped, and it is determined whether or not the engine restart condition is satisfied in step S8 described later.

If it is determined in step S2 that the idle stop is not being executed (NO), it is determined in step S3 whether an idle stop execution condition (engine stop condition) is satisfied. Here, the idle stop execution condition is to satisfy all the following individual conditions. Note that the idle stop execution condition or individual condition is merely an example, and it is needless to say that the idle stop execution condition according to the present invention is not limited thereto. For example, one of the following individual conditions may be deleted, or another individual condition may be added.
(1) The accelerator opening is 0 (accelerator off).
(2) The brake is on.
(3) The vehicle speed is zero.
(4) The battery voltage is equal to or higher than a predetermined set value.
(5) The battery state of charge (SOC) is greater than or equal to a predetermined set value.
(6) The battery deterioration state (SOH) is less than a predetermined set value.
(7) The battery discharge depth is less than the battery discharge depth limit value.

  If it is determined in step S3 that the idle stop execution condition is not satisfied (NO), that is, if one of the individual conditions is not satisfied, the idle stop cannot be executed. All steps S3 to S9 are skipped, and the process returns to step S1 (return). On the other hand, if it is determined in step S3 that the idle stop execution condition is satisfied (YES), that is, if all the individual conditions are satisfied, the idle stop is executed in step S4. That is, fuel injection from the fuel injection valve 2 is stopped, spark discharge by the spark plug 3 is stopped, and the engine 1 is stopped.

  After the idle stop is executed in this way, first, in step S5, an idle stop frequency per predetermined period (hereinafter referred to as “idle stop frequency” for short) is calculated. Here, the predetermined period is, for example, a period until the integrated value of the time during which an ignition switch (not shown) is on (that is, the operating time of the engine 1 including the idle stop state) reaches a predetermined set value. It is. It should be noted that a predetermined time may be simply set as the predetermined period regardless of whether the ignition switch is turned on or off. As a result, the battery discharge depth limit value can be set or changed according to the latest changes in the driving environment, and the opportunity or period for performing the idle stop is ensured to the maximum while effectively suppressing the deterioration of the battery 6. can do.

  Next, in step S6, based on the idle stop frequency, a battery discharge depth limit value that is one element of the idle stop execution condition and one element of the engine restart condition is calculated. Note that the battery discharge depth is an integrated value of the amount of electricity discharged from the battery 6. For example, if the battery discharge depth at a certain point is 5%, the amount of charge or the remaining amount of electricity at the point in time is 6 is 95% of the amount of charge or the remaining amount of electricity when fully charged.

  As shown in FIG. 3, the battery discharge depth limit value is a value determined according to the idle stop frequency, and the battery discharge depth limit value decreases as the idle stop frequency increases. That is, when the idle stop frequency is high, the battery discharge depth limit value is decreased, the idle stop execution frequency is decreased, or the idle stop is released, that is, the engine 1 is restarted so that the deterioration due to the discharge of the battery 6 does not proceed. I'm trying to speed up. On the other hand, when the idling stop frequency is low, the battery discharge depth limit is increased, the idling stop opportunity is increased as much as possible, or the idling stop period is made as long as possible to improve fuel efficiency and reduce carbon dioxide production. I try to plan.

  FIG. 4 shows a relationship between the battery discharge depth and the number of charge / discharge cycles until the battery 6 is in a certain deterioration state (for example, a state in which the battery should be replaced). This data is obtained when the battery 6 is used in an environment of 40 ° C. As is clear from FIG. 4, the greater the battery discharge depth, the smaller the number of discharge cycles. That is, when the battery discharge depth is large, the battery 6 is rapidly deteriorated and its life is shortened. Therefore, it is necessary to appropriately control the battery discharge depth in order to increase the idle stop opportunities as much as possible while suppressing the deterioration of the battery 6 or to make the idle stop period as long as possible. Therefore, in this idle stop control, the battery discharge depth limit value is changed according to the operating state of the engine 1.

Next, in step S7, the battery discharge depth limit value is weighted. That is, the battery discharge depth limit value is gradually changed according to the change in the idle stop frequency. As a result, it is possible to eliminate or suppress an occupant's uncomfortable feeling due to an abrupt change in the opportunity or period for executing idle stop with respect to changes in the driving environment. The weighting process of the battery discharge depth limit value is performed by, for example, the following formula 1.
A = A _i × α + A _i−1 × (1-α) …………………………………………
A: Weighted battery discharge depth limit value
A _i : battery discharge depth limit value calculated this time
A _i-1 : battery discharge depth limit value calculated last time
α: Weighting coefficient (0 <α <1)

  Subsequently, in step S8, it is determined whether or not an engine restart condition is satisfied. In this idle stop control, when at least one of the individual conditions in the idle stop execution condition is no longer satisfied, the idle stop is canceled and the engine 1 is restarted. That is, in this idle stop control, the engine restart condition is that the idle stop execution condition is not satisfied. Of course, the engine restart condition is not limited to this.

  If it is determined in step S8 that the engine restart condition is satisfied (YES), in step S9, fuel injection from the fuel injection valve 2 is resumed, and spark discharge by the spark plug 3 is resumed. The engine 1 is restarted. Thereafter, the control returns to step S1 (return). On the other hand, if it is determined in step S8 that the engine restart condition is not satisfied (NO), step S9 is skipped to return to step S1 in order to continue the idle stop.

  As a result of such idle stop control, when the automobile is used in an environment where the idle stop frequency is high, for example, mainly in an urban area, that is, in an environment where deterioration of the battery 6 due to idle stop is likely to proceed. In this case, since the battery discharge depth limit value becomes small, it is possible to effectively suppress the deterioration of the battery 6 due to the idle stop. On the other hand, when the vehicle is used in an environment where the idle stop frequency is low, for example, in a suburb or a depopulated area, that is, when the battery 6 is not easily deteriorated due to the idle stop, the battery discharge is performed. Since the depth limit value becomes large, it is possible to increase the number of opportunities to perform idle stop as much as possible without causing problems (for example, battery exhaustion) in restarting the engine 1 from the idle stop state, or execute idle stop. The period to do as long as possible.

  That is, the deterioration of the battery 6 caused by the idle stop can be suppressed, and the opportunity or period for executing the idle stop can be maximized without causing any trouble in restarting the engine 1 from the idle stop state. It can be ensured, fuel efficiency can be improved, and the amount of carbon dioxide produced can be reduced.

It is a schematic diagram which shows the outline | summary of the electric system of the engine which concerns on embodiment of this invention. It is a flowchart which shows the control method of the idle stop control in the engine shown in FIG. It is a graph which shows the relationship between idle stop frequency and a battery discharge depth limit value. It is a graph which shows the relationship between a battery discharge depth and the number of charging / discharging cycles until a battery will be in a fixed deterioration state.

Explanation of symbols

C control unit, 1 engine, 2 fuel injection valve, 3 spark plug, 4 crankshaft, 5 electric load, 6 battery, 6a battery positive pole, 6b battery negative pole, 7 alternator, 8 drive pulley, 9 rotating shaft, 10 driven pulley, 11 V belt, 12 starter, 13 plus side conductor, 14 first current sensor, 15 second current sensor, 16 minus side conductor, 17 grounding part, 18 voltage sensor, 20 vehicle speed sensor, 21 accelerator opening sensor , 22 Brake switch.

Claims (3)

An automatic stop / restart control means is provided for automatically stopping the engine when a predetermined engine stop condition is satisfied, and restarting the engine when the predetermined engine restart condition is satisfied after the engine is stopped. An engine automatic stop control device in which one of the engine restart conditions is that the discharge depth of the battery is equal to or greater than a predetermined discharge depth limit value while the engine is stopped.
Stop frequency detecting means for detecting the frequency of the engine stop by the automatic stop / restart control means;
Discharge depth limit value setting means for setting the discharge depth limit value small when the stop frequency detected by the stop frequency detection means is large, and setting the discharge depth limit value large when the stop frequency is low. An automatic stop control device for an engine.   The engine automatic stop control device according to claim 1, wherein the discharge depth limit value setting means gradually changes the discharge depth limit value with respect to the change in the stop frequency. The automatic stop control device for an engine according to claim 1, wherein the stop frequency detecting means detects the engine stop frequency for every predetermined period while the vehicle equipped with the engine is running.

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