JP5379713B2 - Idling stop vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the fuel economy performance by increasing frequency of idling stop. <P>SOLUTION: In the case wherein the vehicle speed is lower than a predetermined vehicle speed V1 and wherein a charge condition SOCm of a main battery is lower than a predetermined value S1, the main battery is quickly charged. The main battery can be sufficiently charged for idling stops by quickly charging the main battery just before stopping the vehicle. With this structure, the frequency of idling stop can be increased, and the fuel economy performance of the idling stop vehicle can be improved. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an idling stop vehicle that automatically stops an engine.

  In order to improve the fuel efficiency of the vehicle, an idling stop vehicle has been developed in which the engine is stopped when the vehicle is temporarily stopped (for example, see Patent Document 1). In this idling stop vehicle, not only the alternator is stopped together with the engine, but also the starter motor needs to be driven frequently, so that required values for the output and capacity of the battery are high. Therefore, in the idling stop vehicle of Patent Document 1, a lithium ion battery is mounted in addition to the lead storage battery.

JP 2004-225649 A

  However, in the idling stop vehicle of Patent Document 1, charging / discharging control of the battery is not performed in preparation for idling stop, and therefore idling stop is limited depending on the state of charge of the battery. That is, in order to execute the idling stop, it is necessary to secure electric power necessary for the battery when the engine is stopped or the engine is restarted. For this reason, when the battery is not sufficiently charged, it is impossible to stop idling even if an idling stop opportunity comes. Such a restriction on idling stop has been a factor of lowering fuel efficiency.

  An object of the present invention is to improve fuel efficiency by increasing the number of idling stops.

An idling stop vehicle according to the present invention is an idling stop vehicle that automatically stops an engine when a predetermined stop condition is satisfied, and includes a first power storage unit connected to a generator and a first power storage unit connected to an electric load. If the state of charge of the first power storage unit falls below a predetermined value when the power storage unit is below a predetermined vehicle speed, the first power storage unit is mounted until the state of charge of the first power storage unit exceeds a predetermined value. have a charge control unit for charging the first power supply system is constituted by the generator and the first power storage unit, the second power supply system is constituted by the electrical load and the second power storage unit, the first power supply A switch that is switched to an open state for separating the first power supply system and the second power supply system is provided between the system and the second power supply system, and the charge control unit switches the switch to the open state. State In, the charging voltage applied to the first power storage unit, and setting the above upper limit voltage of the second power supply system.

  In the idling stop vehicle of the present invention, the first power storage unit is a rocking chair type power storage unit.

  According to the present invention, when the charge state of the first power storage unit is lower than the predetermined value when the vehicle speed is lower than the predetermined vehicle speed, the first power storage unit is charged until the charge state becomes equal to or higher than the predetermined value. It is possible to ensure the charged state of the first power storage unit in preparation for the stop. Thereby, the number of idling stops can be increased, and the fuel efficiency can be improved.

It is the schematic which shows the structure of the idling stop vehicle which is one embodiment of this invention. It is explanatory drawing which shows the relationship of the brake operation in idling stop control, a vehicle speed, and an engine speed. It is explanatory drawing which shows the charging / discharging state of the main battery when performing idling stop control. It is explanatory drawing which shows the electric power supply state of the power supply device at the time of idling stop. (a) And (b) is explanatory drawing which shows the electric power supply state of the power supply device at the time of engine starting. (a) And (b) is explanatory drawing which shows the electric power supply state of the power supply device at the time of engine operation. It is the schematic which shows the structure of the power supply device with which the idling stop vehicle which is other embodiment of this invention is provided. (a) And (b) is explanatory drawing which shows the electric power supply state of the power supply device at the time of engine operation. It is explanatory drawing which shows the electric power supply state of the power supply device at the time of idling stop and engine starting.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of an idling stop vehicle 10 according to an embodiment of the present invention. As shown in FIG. 1, a power supply device 13 including two batteries 11 and 12 is mounted on an idling stop vehicle 10 (hereinafter referred to as a vehicle). The vehicle 10 is equipped with an engine 14 and an automatic transmission 15. Drive wheels 18 are connected to an output shaft 16 of the automatic transmission 15 via a differential mechanism 17. A starter motor 19 is assembled to the engine 14. Further, an alternator 20 that is a generator is connected to the engine 14 via a drive belt 21. The illustrated vehicle 10 has an idling stop function, and the engine 14 is automatically stopped when the vehicle is temporarily stopped. In this way, the fuel efficiency of the vehicle 10 is improved by actively stopping the engine 14.

  The power supply device 13 is provided with a main battery 11 as a first power storage unit. A starter motor 19 and an alternator 20 are connected to the main battery 11. Thus, the first battery system 25 is constituted by the main battery 11, the starter motor 19 and the alternator 20. The allowable voltage range of the main battery 11 and the alternator 20 constituting the first power supply system 25 is set to about 12 to 18V. That is, the upper limit voltage on the control of the main battery 11 and the alternator 20 is set to 18V. Moreover, as the main battery 11, a power storage unit having a small charge / discharge resistance and excellent cycle characteristics is used. Examples of such a power storage unit include so-called rocking chair type power storage units such as a lithium ion battery, a lithium ion capacitor, an electric double layer capacitor, and a nickel metal hydride battery. Here, the rocking chair type power storage unit refers to a power storage unit that is charged and discharged by reciprocation of lithium ions, hydrogen ions, and the like between electrodes. The power storage mechanism of the rocking chair type power storage unit has the characteristics that the charge / discharge resistance is small and the cycle characteristics are excellent because the physical structure change (dissolution / precipitation) of the electrode is not involved.

  The power supply device 13 is provided with a sub-battery 12 as a second power storage unit. An electrical component 29 such as a headlight 26, an ignition coil 27, and an injector 28 is connected to the sub-battery 12 as an electrical load. Thus, the second power supply system 30 is configured by the sub battery 12 and the electrical component 29. The allowable voltage range of the sub-battery 12 and the electrical component 29 constituting the second power supply system 30 is set to about 12 to 15V. That is, the upper limit voltage on the control of the sub-battery 12 and the electrical component 29 is set to 15V. Further, as the sub-battery 12, a power storage unit having a predetermined power storage capacity is used. The storage capacity of the sub-battery 12 is set in consideration of the starting performance after leaving the vehicle for a predetermined period (for example, three months). Examples of such a power storage unit include a so-called reserve power storage unit such as a lead storage battery having a low storage cost and a large storage capacity. Here, the reserve type power storage unit refers to a power storage unit that performs charging / discharging by dissolving ions in the electrolytic solution from the metal of the electrode and the like, and depositing ions in the electrolytic solution on the electrode as metal or the like. The power storage mechanism of the reserve power storage unit has the characteristics that the charge / discharge resistance is large and the cycle characteristics are poor compared to the rocking chair type power storage unit because it involves the physical structural change (dissolution / deposition) of the electrode. However, since an inexpensive electrode material such as lead can be used, there is a feature that it is easy to obtain a large storage capacity. Further, the sub battery 12 is not limited to the reserve type power storage unit, and a rocking chair type power storage unit may be used as the sub battery 12 as long as a predetermined power storage capacity can be secured at low cost.

  In addition, a switch 32 such as an n-channel FET is provided in the energization line 31 that connects the first power supply system 25 and the second power supply system 30. By switching the switch 32 to the connected state, the first power supply system 25 and the second power supply system 30 can be electrically connected. On the other hand, the first power supply system 25 and the second power supply system 30 can be electrically disconnected by switching the switch 32 to the open state. In this way, by setting the power generation voltage of the alternator 20 to exceed the upper limit voltage (15V) of the second power supply system 30 by opening the switch 32 and disconnecting the alternator 20 and the main battery 11 from the second power supply system 30. Is possible. That is, the charging voltage applied to the main battery 11 is set to be equal to or higher than the upper limit voltage of the second power supply system 30. As a result, the power generation amount of the alternator 20 can be dramatically increased.

  Hereinafter, idling stop control for automatically stopping the engine 14 will be described. In order to execute idling stop control, the vehicle 10 is provided with a control unit 33. The control unit 33 includes a CPU that executes programs, a ROM that stores programs, a RAM that temporarily stores data, input / output ports connected to various sensors, actuators, and the like. The sensors connected to the control unit 33 include a brake pedal sensor 34 that detects the operation status of the brake pedal, an accelerator pedal sensor 35 that detects the operation status of the accelerator pedal, a vehicle speed sensor 36 that detects the vehicle speed, and the voltage of the main battery 11. A voltage sensor 37 that detects the current of the main battery 11, a temperature sensor 39 that detects the temperature of the main battery 11, a voltage sensor 40 that detects the voltage of the sub battery 12, and a current of the sub battery 12. Current sensor 41 or the like.

  FIG. 2 is an explanatory diagram showing the relationship between brake operation, vehicle speed, and engine speed in idling stop control. The control unit 33 determines the stop condition of the engine 14 based on the brake operation, the vehicle speed, and the like. That is, as shown in FIG. 2, when the vehicle speed is reduced to 0 km / h under the state where the brake pedal is depressed (brake ON) (symbol a), the stop condition of the engine 14 is controlled by the control unit 33. Is determined to hold. Then, the control unit 33 outputs a stop signal to the ignition coil 27, the injector 28, etc., and stops the engine 14. Subsequently, when the depression of the brake pedal is released during idling stop (engine stop) (brake OFF, symbol b), the control unit 33 determines that the stop condition of the engine 14 is not satisfied. Then, the control unit 33 outputs a start signal to the starter motor 19, the ignition coil 27, the injector 28, and the like to restart the engine 14. By the way, in order to perform idling stop, it is necessary to fully charge the main battery 11 in order to ensure power consumption during engine stop or engine restart. That is, when the state of charge SOCm representing the power storage ratio of the main battery 11 is lower than the predetermined value S1, idling stop is limited because it is difficult to secure power during engine stop or engine restart.

  Therefore, the control unit 33 functioning as a charge control unit performs charge control on the main battery 11 as follows in order to ensure the amount of power stored in the main battery 11 in preparation for idling stop. Here, FIG. 3 is an explanatory diagram showing a charge / discharge state of the main battery 11 when the idling stop control is executed. FIG. 4 is an explanatory diagram showing a power supply state of the power supply device 13 when idling is stopped. FIGS. 5A and 5B are explanatory diagrams showing the power supply state of the power supply device 13 when the engine is started. FIGS. 6A and 6B are explanatory views showing the power supply state of the power supply device 13 when the engine is operating. In FIGS. 4 to 6, the power supply state is represented using black arrows.

  First, as shown in FIG. 3, when idling is stopped, power is supplied from the main battery 11 to the various electrical components 29, so that the state of charge SOCm of the main battery 11 gradually decreases. At this time, as shown in FIG. 4, the switch 32 is controlled to be connected by the control unit 33, and the main battery 11 and the sub battery 12 are connected to the electrical component 29. Here, the voltage range in which the storage capacity of the main battery 11 can be exhibited is designed to be higher than the voltage range in which the storage capacity of the sub battery 12 can be exhibited. For this reason, power is mainly supplied from the main battery 11 to the electrical component 29, while power supply from the sub battery 12 is suppressed. In this manner, by suppressing charging / discharging of the sub battery 12, it is possible to prevent the sub battery 12 made of a reserve power storage unit or the like from being deteriorated. In addition, since the cycle characteristics of the main battery 11 made of the rocking chair type power storage unit are good, the main battery 11 does not deteriorate significantly even if it is charged and discharged frequently.

  Subsequently, as shown by the symbol a in FIG. 3, when the engine is started after the idling stop, as shown in FIG. 5A, the switch 32 is switched to the open state by the control unit 33. The starter motor 19 is supplied with electric power from the main battery 11, and the electric component 29 such as the ignition coil 27 and the injector 28 is supplied with electric power from the sub battery 12. In this way, the starter motor 19 is driven by the large electric power from the main battery 11 and the electric component 29 is supplied with the large storage capacity of the sub battery 12, so that the engine 14 can be quickly restarted and the electric component 29 can be supplied. Thus, it is possible to achieve both instantaneous power failure prevention of the electrical component 29 by supplying a stable voltage. When the engine is difficult to start, the starter motor 19 may be driven with the switch 32 connected as shown in FIG. 5B. Thereby, the starter motor 19 can be driven by the electric power from the main battery 11 and the sub-battery 12, and the engine 14 can be restarted quickly even in a low temperature environment.

  Further, as shown in FIG. 3, normal charging of the main battery 11 and the sub-battery 12 is performed during engine operation after engine startup. Thereby, the state of charge SOCm of the main battery 11 gradually increases. At this time, as shown in FIG. 6A, the control unit 33 controls the switch 32 to be in a connected state, so that the first power supply system 25 and the second power supply system 30 are electrically connected. That is, during normal charging, the power generation voltage of the alternator 20 is limited to 15V or less in order to protect the second power supply system 30 whose upper limit voltage is 15V.

  Subsequently, as shown in FIG. 3, when the vehicle speed falls below a predetermined vehicle speed V1 (for example, 10 km / h) (reference number b), when the state of charge SOCm of the main battery 11 falls below a predetermined value S1, the idling stop is performed. In addition, the main battery 11 is rapidly charged. As a result, the state of charge SOCm of the main battery 11 can be increased so as to exceed the predetermined value S1 (reference symbol c). At this time, as shown in FIG. 6B, the switch 32 is switched to the open state by the control unit 33, and the first power supply system 25 and the second power supply system 30 are electrically disconnected. Thus, the alternator 20 and the main battery 11 can be disconnected from the second power supply system 30, and the generated voltage of the alternator 20 can be raised to the upper limit voltage (18 V) of the first power supply system 25. That is, at the time of rapid charging, the generated voltage of the alternator 20 can be controlled exceeding the upper limit voltage (15 V) of the second power supply system 30. In this way, by performing rapid charging with a generated voltage (generated power) higher than normal charging, the main battery 11 can be sufficiently charged in a short time until the vehicle stops.

  As described above, since the main battery 11 is rapidly charged immediately before stopping, the state of charge SOCm of the main battery 11 can be raised to a predetermined value S1 or more in preparation for idling stop. Thereby, the engine 14 can be stopped without missing an idling stop opportunity, and the fuel efficiency of the vehicle 10 can be improved. That is, as indicated by reference symbol d in FIG. 3, even if the state of charge of the main battery 11 is lower than the predetermined value S1 when the vehicle is stopped under normal charging, rapid charging is performed immediately before stopping as shown by reference symbol c. It is possible to secure the state of charge SOCm exceeding the predetermined value S1 by performing the above. In addition, since the quick charging is performed at the time of deceleration immediately before stopping, the main battery 11 can be charged without increasing the engine load. Moreover, since idling stop cancellation resulting from insufficient charging of the main battery 11 can be reduced, it is possible to enhance the satisfaction of the driver who expects idling stop. Furthermore, even when the ignition switch is turned off after the vehicle stops, the engine startability at the next boarding can be improved by charging the main battery 11 immediately before the vehicle stops.

  In the above description, when the state of charge SOCm falls below the predetermined value S1 immediately before stopping, the main battery 11 is rapidly charged until the minimum required value S1 is recovered. However, the present invention is not limited to this. Alternatively, a predetermined value higher than the predetermined value S1 may be set as a target value for rapid charging. Further, as a method for calculating the state of charge SOCm in the main battery 11, for example, a calculation method described in Japanese Patent Application Laid-Open No. 2005-201743 can be used. In this calculation method, the state of charge SOCc based on the integrated value of the charge / discharge current and the state of charge SOCv based on the estimated open-circuit voltage are calculated, and the state of charge SOCm and SOCv are weighted and combined to calculate the state of charge SOCm. It is a method to do. It is not restricted to this calculation method, You may calculate charge condition SOCm using another calculation method.

  In the above description, the switch 32 is provided between the first power supply system 25 and the second power supply system 30 in order to raise the power generation voltage of the alternator 20 at the time of rapid charging. However, the present invention is not limited to this. The switch 32 may be reduced from between the first power supply system 25 and the second power supply system 30. In this case, the generated voltage of the alternator 20 is controlled within the allowable voltage range (about 12 to 15 V) of the second power supply system 30. For example, the generated voltage of the alternator 20 is set to 13.5 V during normal charging, and the generated voltage of the alternator 20 is set to 15 V during rapid charging. In this way, the main battery 11 may be rapidly charged by raising the power generation voltage of the alternator 20 within the allowable voltage range (about 12 to 15 V) of the second power supply system 30.

  In the above description, the power supply device 13 including the first power supply system 25 and the second power supply system 30 is mounted on the vehicle 10, but the power supply device 13 is not limited to this, and other power supply devices are provided. The present invention may be applied to a different vehicle. Here, FIG. 7 is a schematic diagram showing a configuration of a power supply device 50 provided in an idling stop vehicle according to another embodiment of the present invention. In FIG. 7, members similar to those shown in FIG. 1 are given the same reference numerals and description thereof is omitted.

  As shown in FIG. 7, the alternator 20 and the electrical component 29 are connected via a power supply line 51 that bypasses the main battery 11. The power supply line 51 is provided with a first switch SW1 made of an n-channel FET or the like. The positive line 52 of the main battery 11 is connected to the electrical component 29, and the negative line 53 of the main battery 11 is connected to the plus terminal of the alternator 20. Thus, the main battery 11 and the alternator 20 are connected in series. The negative line 53 is provided with a second switch SW2 made of an n-channel FET or the like. Further, a ground line 54 is connected to the negative electrode line 53 between the switch SW2 and the main battery 11. The connection point 55 between the switch SW2 and the main battery 11 is grounded by the ground line 54. The ground line 54 is provided with a third switch SW3 made of an n-channel FET or the like. The positive line 56 of the sub battery 12 is connected to the electrical component 29, and the negative line 57 of the sub battery 12 is grounded. As described above, the sub battery 12 is connected in parallel to the main battery 11 and the alternator 20.

  Even in a vehicle equipped with such a power supply device 50, it is possible to reduce idling stop cancellation due to insufficient charging of the main battery 11 by performing rapid charging on the main battery 11 immediately before stopping. . Here, FIGS. 8A and 8B are explanatory views showing the power supply state of the power supply device 50 when the engine is operating. FIG. 9 is an explanatory diagram showing the power supply state of the power supply device 50 when idling is stopped and when the engine is started. In FIGS. 8 and 9, the power supply state is represented using black arrows.

  As shown in FIGS. 8A and 8B, when the engine is operating, the switches SW1 and SW3 are switched to the connected state, and the switch SW2 is switched to the open state. As a result, the power generated by the alternator 20 is supplied to the main battery 11, the sub battery 12, and the electrical component 29. Then, as shown in FIG. 8A, during normal charging other than immediately before stopping, the power generation voltage of the alternator 20 is kept low (for example, 13.5 V). Further, as shown in FIG. 8 (b), the power generation voltage of the alternator 20 is raised (for example, 15V) at the time of rapid charging immediately before stopping. The power generation voltage of the alternator 20 is controlled within the allowable voltage range (about 12 to 15 V) of the sub battery 12 and the electrical component 29. Further, as shown in FIG. 9, at the time of idling stop or engine start, the switches SW1 and SW2 are switched to the open state, and the switch SW3 is switched to the connected state. Thereby, power from the main battery 11 and the sub battery 12 is supplied to the electrical component 29. The illustrated electrical component 29 includes a starter motor 19.

  In the illustrated power supply device 50, since the main battery 11 and the alternator 20 are connected in series, the main battery 11 can be deeply discharged without being limited by the lower limit voltage of the sub battery 12 or the electrical component 29. It has become. That is, the generated voltage of the alternator 20 is raised in accordance with the voltage drop of the main battery 11 under the state where the switches SW1 and SW3 are switched to the open state and the switch SW2 is switched to the connected state. As a result, even when the main battery 11 is deeply discharged, the applied voltage to the sub-battery 12 and the electrical component 29 can be held above the lower limit voltage. Therefore, the storage capacity of the main battery 11 can be fully utilized.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the illustrated case, the present invention is applied to the vehicle 10 having only the engine 14 as a power source. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention may be applied. Moreover, although the main battery 11 and the sub battery 12 are mounted on the vehicle 10 shown in the figure, the present invention is not limited to this, and the present invention may be applied to a vehicle on which the sub battery 12 is not mounted. .

  In the above description, the present invention is applied to the vehicle 10 provided with the automatic transmission 15. However, the present invention is not limited to this, and the present invention may be applied to a vehicle provided with a manual transmission. . In a vehicle equipped with a manual transmission, the stop condition of the engine 14 is determined based on information such as an operation state of a clutch pedal, a shift position, and a vehicle speed. In the above description, the engine 14 is stopped after the vehicle is completely stopped. However, the present invention is not limited to this, and the engine 14 may be stopped before the vehicle is completely stopped.

  Further, in the case shown in FIG. 3, the normal charging is always performed when the engine is operated. However, the present invention is not limited to this, and the normal charging may be stopped according to the traveling state of the vehicle 10. For example, it is conceivable to perform normal charging during deceleration while stopping normal charging during acceleration. Thereby, the alternator 20 can be controlled so as not to increase the engine load, and the fuel efficiency of the vehicle 10 can be improved.

  In the above description, the alternator 20 and the starter motor 19 are separately provided. However, an electric motor having the functions of the alternator 20 and the starter motor 19 may be provided. Further, in the above description, the allowable voltage range of the first power supply system 25 is set to about 12 to 18 V, but is not limited to this voltage range. Similarly, the allowable voltage range of the second power supply system 30 is set to about 12 to 15 V, but is not limited to this voltage range.

10 Idling stop vehicle 11 Main battery (first power storage unit)
12 Sub-battery (second power storage unit)
14 Engine 20 Alternator (generator)
25 First power supply system 26 Headlight (electric load)
27 Ignition coil (electric load)
28 Injector (electric load)
29 Electrical components (electric load)
30 Second power supply system 32 Switch 33 Control unit (charging control means)
S1 predetermined value V1 predetermined vehicle speed

Claims (2)

An idling stop vehicle that automatically stops the engine when a predetermined stop condition is satisfied,
A first power storage unit connected to the generator;
A second power storage unit connected to the electrical load;
When the charging state of the first power storage unit is lower than a predetermined value when the vehicle speed is lower than the predetermined vehicle speed, the charging control unit charges the first power storage unit until the charging state of the first power storage unit becomes a predetermined value or more. It has a door,
A first power supply system is configured by the generator and the first power storage unit,
A second power supply system is configured by the electrical load and the second power storage unit,
Provided between the first power supply system and the second power supply system is a switch that is switched to an open state that separates the first power supply system and the second power supply system,
The charging control means sets the charging voltage applied to the first power storage unit to be equal to or higher than an upper limit voltage of the second power supply system under a state where the switch is switched to an open state. Stop vehicle. The idling stop vehicle according to claim 1,
The idling stop vehicle, wherein the first power storage unit is a rocking chair type power storage unit.

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