Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R16/00—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for
  • B60R16/02—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements
  • B60R16/03—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements for supply of electrical power to vehicle subsystems or for
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/007—Regulation of charging or discharging current or voltage
  • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
  • H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/14—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
  • H02J7/1446—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle in response to parameters of a vehicle
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
  • H02J2310/40—The network being an on-board power network, i.e. within a vehicle
  • H02J2310/46—The network being an on-board power network, i.e. within a vehicle for ICE-powered road vehicles
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
  • Y02T10/92—Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Definitions

• the present invention relates to a power system for a vehicle, which includes a generator and a battery.
• a well-known power system installed in a vehicle is configured by using two batteries, i.e. a lead battery and a lithium ion battery. Using these batteries properly, electrical power is supplied to various electrical loads installed in the vehicle.
• a patent document JP-A-2012-080706 discloses a specific configuration of such a power system in which a lithium ion battery is electrically connected to a generator and a lead battery via a semiconductor switch.
• the configuration disclosed in JP-A-2012-080706 embodies idle reduction control.
• the engine is automatically stopped when predetermined automatic stop conditions are met, and is automatically restarted when predetermined restart conditions are met in a state where the engine has been automatically stopped.
• An embodiment provides a power system for a vehicle, which can effectively perform idle reduction control.
• a power system for a vehicle in which idle reduction control is performed, under which an engine is automatically stopped when a predetermined automatic stop condition is met, and automatically restarted when a predetermined restart condition is met in a state where the engine is automatically stopped.
• the power system includes a generator which is driven on the basis of output of the engine; a battery which is connected to the generator; and a controller which allows the generator to generate power when an amount of charge of the battery has decreased below a lower limit, and which sets the lower limit to a higher level when the speed of the vehicle has exceeded a predetermined speed than in a case where a speed of the vehicle has not exceeded the predetermined speed.
• Fig. 1 is a schematic diagram illustrating a power system, according to a first embodiment
• Fig. 2 is a table showing upper and lower limits of a lead battery state of charge PbSOC for several conditions, according to the first embodiment
• Fig. 3 is a flow diagram illustrating a process of charge amount retaining control, according to the first embodiment
• Fig. 4 is a time diagram illustrating vehicle speed relative to upper and lower limits of PbSOC, according to the first embodiment
• Fig. 5 is a table showing upper and lower limits of PbSOC for several conditions, according to a second embodiment
• Fig. 6 is a flow diagram illustrating a process of charge amount retaining control, according to the second embodiment
• Fig. 7 is a time diagram illustrating vehicle speed relative to upper and lower limits of PbSOC, according to the second embodiment
• Fig. 8 is a time diagram illustrating vehicle speed relative to upper and lower limits of PbSOC, according to a modification
• Fig. 9 is a time diagram illustrating vehicle speed relative to upper and lower limits of PbSOC, according to another modification
• Fig. 10 is a time diagram illustrating vehicle speed relative to upper and lower limits of PbSOC, according to still another modification.
• Fig. 11 is a schematic diagram illustrating a modification of the power system.
• the power system of the present embodiment is an in-vehicle power system which is used being installed in a vehicle.
• the vehicle runs using an engine (internal combustion engine) as a drive source.
• an engine internal combustion engine
• a starter motor is driven to give an initial rotation to the engine.
• Fig. 1 is a schematic diagram illustrating the power system according to the first embodiment.
• the power system includes an alternator 10, lead battery 20, lithium ion battery 30, electrical loads 41, 42 and 43, MOS switch 50 and SMR switch 60.
• the lead battery 20, the lithium ion battery 30 and the electrical loads 41, 42 and 43 are electrically connected in parallel with the alternator 10 (generator) via a power feeder 15 (connecting cable).
• the power feeder 15 forms a power feed path so that power is fed from the alternator 10 to each of the electrical components.
• the lead battery 20 (battery, first battery) is a well-known general-purpose battery.
• the lithium ion battery 30 (second battery) is a high-density battery having high energy efficiency, high power density and high energy density in charging/discharging power compared with the lead battery 20.
• the lithium ion battery 30 is configured by a battery pack in which a plurality of electric cells iare connected in series.
• the lead battery 20 has a charge capacity which is set to be larger than that of the lithium ion battery 30.
• the MOS switch 50 (connection switch) is a semiconductor switch configured by a MOSFET (metal oxide semiconductor field-effect transistor).
• the MOS switch 50 is arranged at a position between the alternator 10 and the lithium ion battery 30. This position also corresponds to a position between the lead battery 20 and the lithium ion battery 30.
• the MOS switch 50 functions as a switch that connects (turns on) and disconnects (turns off) the lithium ion battery 30 to/from the alternator 10 and the lead battery 20.
• the MOS switch 50 is turned on/off by an ECU (electronic control unit) 70. Specifically, an on state (connected state) and an off state (disconnected state) of the MOS switch 50 are switched by the ECU 70.
• the ECU 70 is configured as a well-known microcomputer that includes a CPU and memories (ROM and RAM).
• the SMR switch 60 (battery switch) is a semiconductor switch configured by a MOSFET. In the power feeder 15, the SMR switch 60 is arranged at a position between a connecting portion and the lithium ion battery 30, the connecting portion connecting between the MOS switch 50 and the electrical load 43.
• the SMR switch 60 functions as a switch that connects and disconnects the lithium ion battery 30 to/from the MOS switch 50 and the electrical load 43.
• the SMR switch 60 also functions as an opening/closing means in a time of emergency. Normally, the SMR switch 60 is retained to be in an on state by continuous output of an on signal from the ECU 70. In a time of emergency, the output of the on signal is stopped to bring the SMR switch 60 into an off state. By bringing the SMR switch 60 into an off state, overcharge or overdischarge of the lithium ion battery 30 is avoided.
• the SMR switch 60 may be configured by a normally-open type electromagnetic relay. In this case, even if the ECU 70 breaks down to disable control of the SMR switch 60, the SMR switch 60 is automatically opened to establish disconnection.
• the lithium ion battery 30, the switches 50 and 60, and the ECU 70 are accommodated in a housing (accommodation case) for integration to configure a battery unit U.
• the lithium ion battery 30 is installed with a current sensor, a voltage sensor and a temperature sensor.
• the current sensor measures current that flows out or flows in the lithium ion battery 30.
• the voltage sensor detects a terminal voltage of the lithium ion battery 30.
• the temperature sensor detects a temperature of the lithium ion battery 30. Based on the outputs of these sensors, the ECU 70 detects an output current, an output voltage and a temperature of the lithium ion battery 30.
• the ECU 70 is connected to an ECU (electronic control unit) 80 outside the battery unit U.
• the ECU 80 is connected with a vehicle speed sensor 91 that detects a vehicle speed.
• the ECUs 70 and 80 are connected to each other via a communication network, such as CAN (controller area network), so as to enable intercommunication. Accordingly, various data that are stored in the ECUs 70 and 80 can be shared between these ECUs.
• the ECU 80 (controller) is configured as a well-known microcomputer that includes a CPU and memories (ROM and RAM).
• the electrical load 43 establishes electrical connection on a lithium ion battery 30 side, with respect to the ! MOS switch 50.
• the electrical load 43 is a constant-voltageirequired electrical load which requires that the voltage of supplied power is stable, i.e. the voltage of supplied power is substantially constant or the voltage variation in supplied power falls within a predetermined range. Power supply to the electrical load 43 is mainly taken care by the lithium ion battery 30.
• the electrical load 43 include a navigation system and an audio system.
• the voltage of supplied power is not constant and varies significantly, or varies significantly exceeding the predetermined range, some trouble may be caused.
• the voltage may instantaneously decrease below a minimum operating voltage and reset the operation such as of a navigation system. Therefore, the power supplied to the electrical load 43 is required to be stable at a certain level which will not allow the voltage to decrease below the minimum operating voltage.
• the electrical load 41 is a starter motor that starts the engine, while the electrical load 42 is a generally used electrical load other than the electrical load 43 (constant-voltage-required electrical load) and the starter 41.
• Specific examples of the electrical load 42 include headlights, wipers used such as for a front windshield, a blowing fan for an air conditioner, and a heater used for a defroster of a rear windshield.
• the electrical load 42 includes a drive load that drives a power steering or a power window when predetermined drive conditions thereof are met. Power supply to the starter 41 and the electrical load 42 is mainly taken care by the lead battery 20.
• the alternator 10 generates power using the rotational energy of the crank shaft (output shaft) of the engine.
• the configuration or the like of the alternator 10, which is well known, is omitted from being illustrated but will be briefly explained.
• excitation current passes through the rotor coil, in response to which, AC current is induced in the stator coil.
• the AC current is then converted to DC current by a rectifier.
• the excitation current passing through the rotor coil is adjusted by a regulator of the alternator 10 to thereby adjust the voltage of the generated DC current so as to be a set voltage Vreg.
• the operation of the regulator is controlled by the ECU 80.
• the power generated by the alternator 10 is supplied to the electrical loads 41, 42 and 43, while also being supplied to the lead battery 20 and the lithium ion battery 30.
• power is supplied from the lead battery 20 and the lithium ion battery 30 to the electrical loads 41, 42 and 43.
• deceleration regeneration is performed, in which regenerative energy of the vehicle is used to allow the alternator 10 to generate power to thereby charge both of the batteries 20 and 30.
• the deceleration regeneration is performed when several conditions are met, the several conditions including that the vehicle is in deceleration, fuel injection to the engine is cut, and the like.
• the batteries 20 and 30 are connected in parallel. Accordingly, in charging the batteries with the alternator 10, if the MOS switch 50 is in an on state, the excited current of the alternator 10 flows into a battery whose terminal voltage is lower than the other.
• the terminal voltage of the lithium ion battery 30 is ensured to have much more opportunities of decreasing below the terminal voltage of the lead battery 20, so that the lithium ion battery 30 is charged in preference to the lead battery 20.
• Such a setting can be realized by determining the open-circuit voltages and the internal resistances of the batteries 20 and 30.
• the open-circuit voltages can be determined by selecting a positive-electrode active material, negative-electrode active material and an electrolytic solution of the lithium ion battery 30.
• idle reduction control is performed, under which the engine is automatically stopped when predetermined automatic stop conditions are met, and automatically restarted when predetermined restart conditions are met in a state where the engine is automatically stopped.
• the MOS switch 50 is turned off (disconnected) by the ECU 70. Further, when the engine is restarted, the MOS switch 50 is turned off (disconnected) by the ECU 70 in a state where the lead battery 20 is electrically disconnected from the lithium ion battery 30, so that the starter (electrical load 41) is driven by the lead battery 20.
• the ECU 70 When the vehicle runs in a time period other than the time period of regenerative charge, the ECU 70 turns off the MOS switch 50 and turns on the SMR switch 60.
• the alternator 10 and the lead battery 20 are electrically disconnected from the electrical load 43 while the lithium ion battery 30 is electrically connected to the electrical load 43. Accordingly, the lithium ion battery 30 solely supplies power to the electrical load 43.
• the terminal voltage of the lithium ion battery 30 is ensured to have many more opportunities of decreasing below the terminal voltage of the lead battery 20, so that the generated power can be positively charged to the lithium ion battery 30.
• the lithium ion battery 30 has higher energy efficiency, thereby enhancing the charging/discharging efficiency of the entire power system.
• the lead battery 20 is installed with a current sensor and a voltage sensor.
• the current sensor detects a current that flows out of and flows into the lead battery 20.
• the voltage sensor detects a terminal voltage of the lead battery 20. Detection values derived from these sensors are transmitted to the ECU 80 (battery system control unit).
• the ECU 70 detects an output current and an output voltage of the lithium ion battery 30 on the basis of the outputs of the sensor installed in the lithium ion battery 30.
• Various data of the ECUs 70 and 80 are shared between these ECUs.
• the ECU 80 calculates a SOC (state of charge: percentage (%) of the actual amount of charge with respect to the amount of charge in a fully-charged state) of each of the lead battery 20 and the lithium ion battery 30 on the basis of the detection values derived from the current sensors and the voltage sensors mentioned above.
• the ECU 80 controls power generation of the alternator 10, so that SOC of each of the lead battery 20 and the lithium ion battery 30 will fall in a proper range (so that the batteries will not be overcharged or overdischarged).
• the set voltage Vreg is adjusted by the ECU 80, while the operation of the MOS switch 50 is controlled by the ECU 70.
• SOC of the lead battery 20 is referred to as PbSOC
• SOC of the lithium ion battery 30 is referred to as LiSOC.
• a proper range of LiSOC is about 35% to 80%, while that of PbSOC is about 88% to 92%.
• a proper range (lower limit to upper limit) of PbSOC is finely set according to several conditions.
• a lower limit Dl of PbSOC is set to 89.8% and an upper limit Ul is set to 90.2%.
• a lower limit D2 of PbSOC is set to 89.2% and an upper limit U2 is set to 89.6%.
• the lower limit Dl of PbSOC of Condition 1 is set to be higher than the upper limit U2 of PbSOC of Condition 2.
• the range between the lower and upper limits Dl and Ul of PbSOC of Condition 1 is set so as to be equal to the range between the lower and upper limits D2 and U2 of PbSOC of Condition 2.
• the predetermined speed may be 50 km/h that is a speed for making a determination that the vehicle has a high probability of keeping running, or, in other words, a speed for making a determination that the engine has a low probability of being automatically stopped.
• a lower limit D3 of PbSOC is set to 90.5%, while an upper limit U3 is set to 91.0%. Further, the lower limit D3 of PbSOC of Condition 3 is set to be higher than the upper limit U 1 or U2 of PbSOC of Condition 1 or 2. In other words, when a current discharged from the lead battery 20 has exceeded the predetermined current, the lower limit of PbSOC is set to be higher than in the case where a current discharged from the lead battery 20 has not exceeded the predetermined current.
• the range between the lower and upper limits D3 and U3 of PbSOC of Condition 3 is set to be larger than the range between the lower and upper limits of PbSOC in the case where Condition 3 is not met. Further, the range between the lower and upper limits D3 and U3 of PbSOC of Condition 3 is set to be larger than the range between the lower and upper limits Dl (D2) and Ul (U2) of PbSOC of Condition 1 (2).
• the predetermined current is set to a current for making a determination that the amount of charge of the lead battery 20 decreases faster. *
• a process of control for retaining the amount of charge of the lead battery 20 (charge amount retaining control) on the basis of upper and lower limits of PbSOC.
• the process includes a series of steps, which is repeatedly performed by the ECU 80 at a predetermined cycle.
• step Sll it is determined whether or not a current discharged from the lead battery 20 has exceeded a predetermined current. Specifically, the ECU 80 determines, in a state where no power is generated by the alternator 10, whether or not a current discharged from the lead battery 20 has exceeded a predetermined current, on the basis of a detection value derived from the current sensor of the lead battery 20. If it is determined that the current discharged from the lead battery 20 has exceeded the predetermined current (YES in step Sll), the upper and lower limits of PbSOC are set to the upper and lower limits U3 and D3 of Condition 3.
• step S13 it is determined whether or not the vehicle speed has exceeded a predetermined speed. Specifically, the ECU 80 determines whether or not the vehicle speed has exceeded a predetermined speed, on the basis of a detection value derived from the vehicle speed sensor 91.
• the predetermined speed is set to a higher level in the increase of the vehicle speed (in acceleration) than in the decrease of the vehicle speed (in deceleration) to thereby exhibit hysteresis.
• step S14 it is determined whether or not a time period T2 has expired after the vehicle speed has exceeded the predetermined speed.
• the time period T2 (second time period) is set to a value that can make a determination that the vehicle speed has a low probability of again decreasing below the predetermined speed. If it is determined that the time period T2 has expired after the vehicle speed has exceeded the predetermined speed (YES at step S14), the upper and lower values of PbSOC are set to the upper and lower limits Ul and Dl of Condition 1 (step S15).
• the lower limit of PbSOC is set to a higher level than in the case where the vehicle speed has not exceeded the predetermined speed.
• step S14 if it is determined that the time period T2 has not expired after the vehicle speed has exceeded the predetermined speed (NO in step S14), the upper and lower limits of PbSOC are retained as they are currently set. It should be appreciated that, before start of the series of steps, the upper and lower limits of PbSOC are initially set to the upper and lower limits Ul and Dl of Condition 1.
• step S16 it is determined whether or not a time period T3 has expired after the vehicle speed has decreased below the predetermined speed.
• the time period T3 (third time period) is set to a value that can make a determination that the vehicle speed has a low probability of again exceeding the predetermined speed. If. the time period T3 is determined to have expired after the vehicle speed has decreased below the predetermined speed (YES in step S16), the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 2 (step S17).
• the lower limit of PbSOC is set to a lower level than in the case where the vehicle speed has exceeded the predetermined speed.
• the ECU 80 controls power generation of the alternator 10 on the basis of the set upper and lower limits so that PbSOC falls in a proper range. Specifically, the ECU 80 allows the alternator 10 to generate power when the amount of charge of the lead battery 20 has decreased below the lower limit, but stops power generation of the alternator 10 when the amount of charge of the lead battery 20 has risen above the upper limit. After that, the series of steps of the process is terminated (END).
• Fig. 4 is a time diagram illustrating vehicle speed relative to upper and lower limits of PbSOC. In Fig. 4, proper ranges of PbSOC are shown by hatching between upper and lower limits of PbSOC.
• the upper and lower limits of PbSOC are set to the upper and lower limits U l and Dl of Condition 1.
• the vehicle speed decreases and, at time ti l, decreases below the predetermined speed (in deceleration)
• the upper and lower limits of PbSOC are still retained to be the upper and limits U l and Dl .
• the period T3 which starts from time ti l
• the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 2.
• the upper and lower limits of PbSOC are retained to be the upper and lower limits U l and Dl of Condition 1. Then, at a time point when the engine has come to have a high probability of being automatically stopped, the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 2.
• the lower limit of PbSOC is set to a higher level than in the case where the vehicle speed has not exceeded the predetermined speed (Condition 2). Accordingly, when the vehicle speed has exceeded the predetermined speed and the vehicle has a high probability of keeping running, the lead battery 20 is ensured to have a much more amount of charge than in the case where the vehicle speed has not exceeded the predetermined speed. In contrast, when the vehicle speed has not exceeded the predetermined speed and the engine has a high probability of being automatically stopped, power generation of the alternator 10 is not conducted before the amount of charge of the lead battery 20 becomes lower than in the case where the vehicle speed has exceeded the predetermined speed. Thus, when the vehicle has a high probability of keeping running, the amount of charge is ensured to be large, but when the engine has a high probability of being automatically stopped, more discharge is permitted. As a result, idle reduction control can be effectively performed.
• the lower limit of PbSOC is set to a lower level than under Condition 1.
• the lower limit D3 of PbSOC is set to a higher level than in the case where the current discharged from the lead battery 20 has not exceeded the predetermined current.
• the lower limit D3 of PbSOC is set to be higher than the lower limit Dl of PbSOC in the case where the vehicle speed has exceeded the predetermined speed (Condition 1).
• the amount of charge of the lead battery 20 decreases rapidly, the amount of charge is ensured to be larger than in the case where the vehicle has a high probability of keeping running. Accordingly, when the engine has a high probability of being automatically stopped, power generation of the alternator 10 cans be suppressed. As a result, idle reduction control can be more effectively performed.
• the range between the lower and upper limits D3 and U3 is set to be larger than the range between the lower and upper limits in the case where the current discharged from the lead battery 20 has not exceeded the predetermined current.
• the predetermined speed is set to be higher in the case where the vehicle speed increases (in acceleration), than in the case where the vehicle speed decreases (in deceleration).
• the upper and lower limits of PbSOC are prevented from being frequently changed even when the vehicle speed varies.
• the power system includes the lithium ion battery 30 which is connected to the alternator 10 and the lead battery 20. Therefore, current is discharged from the lead battery 20 to the lithium ion battery 30, allowing PbSOC to easily decrease below the lower limit. Thus, a large amount of charge is ensured when the vehicle has a high probability of keeping running, but when the engine has a high probability of being automatically stopped, power generation of the alternator 10 is suppressed. In this way, a great advantage can be obtained with such a configuration.
• Figs. 5 to 7 hereinafter is described a second embodiment of the present invention.
• the charge amount retaining control shown in Fig. 3 is changed to the one shown, in Fig. 6.
• the remaining configuration is similar to that in the first embodiment. It should be appreciated that, in the second embodiment and in modifications that will be subsequently described, the components or the steps of a control process, which are identical with or similar to those in the first embodiment, are given the same reference numerals for the sake of omitting unnecessary explanation.
• Fig. 5 is a table showing upper and lower limits of PbSOC for several conditions according to the second embodiment. As shown in Fig. 5, in the second embodiment, a proper range of PbSOC is finely set according to several conditions. As shown in Fig. 5, in a state where the engine is in operation (Condition 4), the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl similar to those of Condition 1. In a state where the engine is automatically stopped (Condition 5), the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 similar to those of Condition 2.
• the lower limit of PbSOC is set to a lower level than in a state where the engine is in operation. Irrespective of whether Condition 4 or 5 is met, when a current discharged from the lead battery 20 has exceeded a predetermined current (Condition 3), the upper and lower limits of PbSOC are set to the upper and lower limits U3 and D3 similar to those of Condition 3 described above.
• the relationships between the upper limits Ul, U2 and U3 and the lower limits Dl, D2 and D3, respectively, are the same as those in the first embodiment.
• a process of control for retaining the amount of charge of the lead battery 20 (charge amount retaining control), on the basis of the upper and lower limits of PbSOC.
• the process includes a series of steps, which is repeatedly performed by the ECU 80 at a predetermined cycle.
• step Sll if a current discharged from the lead battery 20 is determined not to have exceeded a predetermined current (NO in step Sll), it is determined whether or not the engine is in operation (step S23). If the engine is determined to be in operation (YES in step S23), it is determined whether or not a time period Tl (first time period) has expired after the engine has been automatically restarted (step S24).
• the time period Tl (first time period) is set to a time period that can make a determination that the vehicle has a high probability of keeping running.
• step S24 if it is determined that the time period Tl has expired from the automatic restart of the engine (YES in step S24), the upper and lower limits of PbSOC are set to the upper and lower limits U 1 and Dl of Condition 4 (step S25). Specifically, in a state where the engine is in operation, on condition that the time period Tl has expired from the automatic restart of the engine, the lower limit of PbSOC is set to a higher level than in a state where the engine is automatically stopped. On the other hand, if it is determined, in step S24, that the time period Tl has not expired from the automatic engine restart (NO in step S24), the upper and lower limits of PbSOC are retained as they are currently set. It should be appreciated that, before starting the series of steps, the upper and lower limits of PbSOC are initially set to the upper and lower limits Ul and Dl of Condition 4.
• step S23 If it is determined, in step S23, that the engine is not in operation, i.e. the engine is in a state of being automatically stopped (NO in step S23), the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 5 (step S26). ⁇
• the ECU 80 controls power generation of the alternator 10 on the basis of the set upper and lower limits, so that PbSOC falls in a proper range. Specifically, the ECU 80 allows the alternator 10 to generate power when the amount of charge of the lead battery 20 has decreased below the lower limit, but stops power generation of the alternator 10 when the amount of charge of the lead battery 20 has risen above the upper limit. After that, the series of steps of the process is terminated (END).
• Fig. 7 is a time diagram illustrating vehicle speed relative to upper and lower limits of PbSOC.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 4.
• the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 5. Therefore, before expiration of the time period Tl from the automatic restart of the engine, power generation of the alternator 10 will not be conducted until PbSOC further decreases.
• the second embodiment specifically described has advantages as set forth below. The advantages similar to those in the first embodiment are omitted.
• the lower limit of PbSOC is prevented from being set to a higher level than in a state where the engine is automatically stopped (Condition 5). Accordingly, when the time period Tl has not expired from the automatic restart of the engine and the engine has a high probability of being automatically stopped again, more discharge is permitted.
• the lower limit of PbSOC is set to a higher level than under Condition 5.
• the lower limit D3 of PbSOC in the case where a current discharged from the lead battery 20 has exceeded a predetermined current is set to a higher level than the lower limit Dl of PbSOC in the case where the vehicle speed has exceeded a predetermined speed (Condition 1).
• the lower limit D3 of PbSOC under Condition 3 may be set to a level equal to the lower limit Dl of PbSOC of Condition 1.
• the lower limit D3 of PbSOC of Condition 3 may be set to a level lower than the lower limit Dl of PbSOC of Condition 1.
• the lower limit D3 of PbSOC in the case where a current discharged from the lead battery 20 has exceeded a predetermined current is set to a level higher than the lower limit Dl of PbSOC in a state where the engine is in operation (Condition 4).
• the lower limit D3 of PbSOC of Condition 3 may be set to a level equal to the lower limit Dl of PbSOC of Condition 4.
• the lower limit D3 of PbSOC of Condition 3 may be set to a level lower than the lower limit Dl of RbSOC of Condition 4.
• a lower limit larger than the lower limit D2 of PbSOC of Condition 2 may be used.
• the predetermined speed when the vehicle speed increases (in acceleration), the predetermined speed is set to a higher level than in the case where the vehicle speed decreases (in deceleration).
• the predetermined speed may be set to the same level both in acceleration and deceleration.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 1. Even when the vehicle speed decreases below the predetermined speed, at time t31, the upper and lower limits of PbSOC are still retained to be the upper and lower limits Ul and Dl. Then, when the time period T3 expires, at time t32, after the vehicle speed has decreased below the predetermined speed, the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 2.
• the upper and lower limits of PbSOC are maintained to the upper and lower limits Ul and Dl of Condition 1. Then, at a time point when the engine has come to have a high probability of being automatically stopped, the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 2.
• the upper and lower limits of PbSOC are still retained to be the upper and lower limits U2 and D2 of Condition 2.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 1. Accordingly, while the vehicle speed has a high probability of again decreasing below the predetermined speed, the upper and lower limits of PbSOC are retained to be the upper and lower limits U2 and D2 of Condition 2.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 1.
• the predetermined speed in acceleration is not required to be changed in deceleration, or vice versa, thereby simplifying the process performed by the ECU 80.
• the upper and lower limits of PbSOC are changed on condition that the period T3 has expired after the vehicle speed has decreased below the predetermined speed, or that the period T2 has expired after the vehicle speed has exceeded the predetermined speed.
• variation of the vehicle speed hardly induces frequent change of the upper and lower limits of PbSOC.
• the upper and lower limit of PbSOC may be changed without meeting the condition of expiring the time period T3 or T2. In this case, as shown in Fig.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 1, in a state where the vehicle speed is initially higher than the predetermined speed.
• the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 2.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 1.
• the lead battery 20 is ensured to have a much higher amount of charge when the vehicle has a high probability of keeping running, and the power generation of the alternator 10 (generator) is suppressed when the engine has a high probability of being automatically stopped.
• the lower limit of PbSOC when the engine is in operation but the time period Tl has not expired from the automatic restart of the engine, the lower limit of PbSOC is prevented from being set to a higher level than in a state where the engine is automatically stopped (Condition 5).
• the upper and lower limits of PbSOC may be changed without meeting the condition of expiring the time period Tl.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 4.
• the upper and lower limits of PbSOC are set to the upper and lower limits U2 and D2 of Condition 5.
• the upper and lower limits of PbSOC are set to the upper and lower limits Ul and Dl of Condition 4.
• power generation of the alternator 10 can be suppressed in a state where the engine is actually automatically stopped.
• the upper and lower limits of PbSOC of Condition 1 are made equal to those of Condition 4.
• the upper and lower limits Ul and Dl of PbSOC of Condition 1 may be different from the upper and lower limits U4 and D4 of PbSOC of Condition 4.
• the upper and lower limits of PbSOC of Condition 2 are made equal to those of Condition 5.
• the upper and lower limits U2 and D2 of PbSOC of Condition 2 may be different from the upper and lower limits U5 and D5 of PbSOC of Condition 5.
• the first and second embodiments may be combined. Specifically, the process including steps S13 to S18 shown in Fig. 3 and the process including steps S23 to S26 shown in Fig. 6 may both be performed. In particular, vehicles that automatically stop the engine before the vehicle speed becomes zero can obtain the advantages of both of the first and second embodiments.
• the power system includes the lead battery 20 and the lithium ion battery 30.
• a power system without including the lithium ion battery 30 may be used.
• the alternator 10 may be permitted to conduct power generation when the amount of charge of the lead battery 20 decreases below the lower limit.
• the lower limit of PbSOC when the vehicle speed has exceeded the predetermined speed, the lower limit of PbSOC may be set to a higher level than in the case where the vehicle speed has not exceeded the predetermined speed. Further, in a state where the engine is automatically stopped, the lower limit of PbSOC may be set to a lower level than in a state where the engine is in operation. As a result, idle reduction control can be effectively performed.
• a power system for a vehicle in which idle reduction control is performed, under which an engine is automatically stopped when a predetermined automatic stop condition is met, and automatically restarted when a predetermined restart condition is met in a state where the engine is automatically stopped.
• the power system includes a generator (10) which is driven! on the basis of output of the engine; a battery (20) which is connectedi to the generator (10); and a controller (80) which allows the generator to generate power when an amount of charge of the battery has decreased below a lower limit, and which sets the lower limit to a ⁇ higher level when the speed of the vehicle has exceeded a predetermined speed than in a case where a speed of the vehicle has not exceeded the predetermined speed.
• the engine is automatically stopped when predetermined automatic stop conditions are met, and automatically restarted when predetermined restart conditions are met in a state where the engine is automatically stopped. Further, when the amount of charge of the battery decreases below the lower limit, power is generated by the generator on the basis of the output of the engine to thereby charge the battery connected to the generator. Thus, when the amount of charge of the battery decreases below the lower limit in a state where the engine is automatically stopped, the engine is restarted to drive the generator.
• the lower limit of the amount of charge is set to a higher level than in the case where the vehicle speed has not exceeded the predetermined speed. Accordingly, when the vehicle speed has exceeded the predetermined speed and the vehicle has a high probability of keeping running, the battery is ensured to have a much higher amount of charge than in the case where the vehicle speed has not exceeded the predetermined speed.
• the vehicle speed has not exceeded the predetermined speed and the engine has a high probability of being automatically stopped power is not generated by the generator before the amount of charge of the battery becomes lower than in the case where the vehicle speed has exceeded the predetermined speed.
• a much higher amount of charge is ensured when the vehicle has a high probability of keeping running, and power generation of the generator is suppressed when the engine has a high probability of being automatically stopped. As a result, idle reduction control can be effectively performed.
• a power system for a vehicle in which idle reduction control is performed, under which an engine is automatically stopped when a predetermined automatic stop condition is met, and automatically restarted when a predetermined restart condition is met in a state where the engine is automatically stopped.
• the power system includes a generator (10) which is driven on the basis of output of the engine; a battery (20) which is connected to the generator (10); and a controller (80) which allows the generator to generate power when an amount of charge of the battery has decreased below a lower limit, and, in a state where the engine is automatically stopped, which sets the lower limit to a lower level than in a state where the engine is in operation.
• the lower limit of the amount of charge is set to a level lower than in a state where the engine is in operation.
• power generation is not performed by the generator before the amount of charge of the battery becomes lower than in a state where the engine is in operation. Accordingly, power generation of the generator is suppressed in a state where the engine is actually automatically stopped. As a result, idle reduction control can be effectively performed.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Mechanical Engineering (AREA)
• Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
• Control Of Charge By Means Of Generators (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

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• 2012
  • 2012-08-07 JP JP2012174781A patent/JP5965775B2/ja active Active
• 2013
  • 2013-08-07 IN IN144DEN2015 patent/IN2015DN00144A/en unknown
  • 2013-08-07 CN CN201380041653.8A patent/CN104541432B/zh active Active
  • 2013-08-07 DE DE112013003970.2T patent/DE112013003970T5/de active Pending
  • 2013-08-07 WO PCT/JP2013/071896 patent/WO2014025064A1/en active Application Filing

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