JP2010098801A - On-board power system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the charge of an on-board battery, which has high charge receivability and is used for power feed to a stator at restart of an engine of idle stop, efficiently in inexpensive constitution. <P>SOLUTION: A system performs double voltage rectification of the AC output of the interphase voltage or single-phase voltage of AC, which is generated by an alternator 11, with a rectifier 15, and charges a second on-board battery 2 high in charge receivability by the rectified output of the rectifier 15. Moreover, the system steps down and regulates the output of the double voltage of the second on-board battery 2 into a voltage higher than that of the first on-board battery 1 by a switching regulator 3 prior to takeout. Then, the system feeds the output of the first on-board battery 1 and the output of the second on-board battery 2 through the switching regulator 3 in parallel to the load of a vehicle including a starter 6, and at restart of an engine of idle stop, the system feeds the output of the second on-board battery 2 preferentially to the starter 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an in-vehicle power supply system for an idle stop vehicle, and more particularly to an improvement in charging of an in-vehicle battery (so-called auxiliary battery) that has high charge acceptance performance and is used for restarting an idle stop engine.

  In general, an idle stop vehicle stops the engine while waiting for a signal to keep the brake pedal depressed while the vehicle is stopped, and the key switch (main switch) is moved to the start position by changing the signal from red to blue. Repeat restarting the engine by operating or releasing the brake pedal. In this case, since the energy consumed during the idling stop cannot be covered by power generation while traveling, not only the vehicle-mounted battery (main battery) such as a conventional 12V lead-acid battery but also the charge acceptance performance and depth can be supplied to the vehicle. It has been proposed to mount an on-board battery (auxiliary battery) such as a nickel metal hydride battery that has a higher discharge resistance than a lead-acid battery, etc., and switch between two types of on-board batteries to drive the electrical load during idle stop and restart (For example, refer to Patent Document 1).

  A conventional in-vehicle power supply system for an idle stop vehicle equipped with two types of in-vehicle batteries is, for example, configured as shown in FIG.

  In FIG. 6, reference numeral 100 denotes an in-vehicle battery (main battery) made of a 12V lead storage battery, and supplies power to various 12V electric loads 120 in the vehicle such as a headlamp and an air conditioner through a fuse 111 of a load power supply path 110.

  An in-vehicle battery (auxiliary battery) 130 made of, for example, a nickel metal hydride battery supplies power to the starter 150 via the starter power supply switching relay 140 when the engine is restarted from the idle stop state. Reference numeral 160 denotes a bidirectional switching regulator as an input / output regulator of the in-vehicle battery 130. As shown in FIG. 7, a four-mode control DC / DC controller 161 having a microcomputer configuration and switching control by the controller 161 are performed. A bridge circuit of a plurality of FETs 162 and a smoothing reactor 163 is provided. The switching regulator 160 operates in any one of four modes of step-up charging / discharging and step-down charging / discharging under the control of the controller 161 based on the state of the in-vehicle battery 130 and the voltage state of the load power supply path 110. The FET 162 is switched to control charging / discharging through the load power supply path 110 of the in-vehicle battery 130. In FIG. 6, the charging path of the in-vehicle battery 130 is indicated by a solid line arrow, and the discharging path is indicated by a broken line arrow.

  Reference numeral 170 in FIG. 6 denotes a key switch (main switch) of the vehicle. The ignition contact 171 is turned on when the ignition is turned on, and the start contact 172 is turned on at the start (start) position. Reference numeral 180 denotes a microcomputer-controlled vehicle control ECU that controls the entire vehicle including the engine. When the engine start and restart are recognized from changes in the contact signals of the contacts 171 and 172, the starter power switch signal SW and start A signal SS is generated. The switching signal SW switches the starter power supply switching relay 140 from the selection contact m of the in-vehicle battery 100 to the selection contact s of the in-vehicle battery 130 except during a cold start. The start signal SS energizes the coil 191 of the starter relay 190 and closes the contact 192 of the starter relay 190 when the shift lever (not shown) is in the parking or neutral position and the switch 200 is on (closed). The starter 150 is excited and driven.

  210 is an alternator with a regulator, and a generator unit 212 attached to the engine based on the control of a control circuit 211 of a microcomputer configuration that exchanges information with the vehicle control ECU 180 has U, V, and W according to the engine output. Three-phase alternating current is generated, and the generated output is supplied to a rectifier 213 formed in a three-phase full bridge of a plurality of diodes D for full-wave rectification, and the output of the rectifier 213 is mounted on the vehicle during engine operation. Power is supplied directly to the battery 100 and also supplied to the in-vehicle battery 130 via the switching regulator 160 to charge the in-vehicle batteries 100 and 130. Note that reference numeral 220 in FIG. 6 denotes a charging alarm lamp for charging abnormality notification that is controlled to be turned on and off by the control circuit 211.

  The in-vehicle battery 100 of a lead storage battery has high short-term discharge performance and low self-discharge during long-term storage, but has low charge acceptance performance and requires time for charging. The in-vehicle battery 130 of a nickel metal hydride battery has higher charge acceptance performance and deep discharge resistance than a lead storage battery, and can be charged in a short time.

  Therefore, in the case of the in-vehicle power supply system of FIG. 6, during cold start from a parking state or the like, the starter power supply switching relay 140 is held at the selected contact m of the in-vehicle battery 100 by the ignition-on operation. 150, and the engine is started, but when the engine is restarted due to an idle stop thereafter (warm start), the starter power supply switching relay 140 is switched to the selected contact s of the in-vehicle battery 130, and the starter 150 is operated by the in-vehicle battery 130. To start the engine.

  While the vehicle is running after starting, the rectifier output of the rectifier 213 based on the acceleration or deceleration engine output is supplied to the vehicle battery 100 to charge the vehicle battery 100, and the rectifier output of the rectifier 213 is switched to the switching regulator. The voltage is adjusted by 160 to supply power to the in-vehicle battery 130, and the in-vehicle battery 130 is also charged.

At this time, the on-vehicle battery 130 with high charge acceptance performance is charged to a fully charged state in a short time until the engine restart at the next idle stop, and the starter for feeding the electric load 120 and engine restart during the next idle stop. Prepare for feeding.
JP-A-2004-150354 (for example, paragraphs [0004], [0017]-[0018], FIG. 1)

  In the case of the conventional system shown in FIG. 6, in order to take advantage of the high charge acceptance performance and deep discharge resistance of the in-vehicle battery 130, the low-voltage rectified output of the rectifier 213 of the alternator 210 is bidirectionally switched as an input / output regulator. The voltage is boosted by the regulator 160 to charge the vehicle-mounted battery 130 to a high voltage, and the output (discharge energy) of the vehicle-mounted battery 130 is preferentially supplied to the electric load 120 during idle stop and to starter power supply for engine restart from idle stop. I use it. In this case, the charging transmission path from the rectifier 213 to the switching regulator 160 has a low voltage and a high current, and has a large loss. As a result, the charging efficiency of the in-vehicle battery 130 decreases. In addition, the diameter of the charging transmission path must be increased, resulting in an increase in cost. In addition, loss due to boosting in the switching regulator 160 also occurs.

  Further, the charging current and the discharging current pass through elements such as the diode D of the rectifier 213 and the FET 162 of the switching regulator 160 that cause a voltage drop during charging and discharging (load power supply) of the in-vehicle battery 130, The number of times that the discharge current passes through the element is large (about 4 to 5 times), and the loss is further increased, and the failure probability of the charge / discharge path is increased and the reliability is lowered.

  Furthermore, the starter power supply at the time of cold start is performed by the output of the in-vehicle battery 100, but since the starter power supply for engine restart at idle stop is also performed by the output of the in-vehicle battery 130, a starter power supply switching relay 140 having a low impedance is required. Each wiring needs to be thick, and the number of parts increases and the manufacturing operation becomes complicated.

  In addition, the rectifier capacity of the alternator 210 must be large enough to cover the charging and charging / discharging loss of the in-vehicle batteries 100 and 130, and there is a problem that the cost increases.

  An object of the present invention is to make it possible to efficiently charge an in-vehicle battery used for starter power supply for engine restart at idle stop with high charge acceptance performance with an inexpensive configuration.

  In order to achieve the above-described object, an in-vehicle power supply system of the present invention includes an alternator that rectifies and outputs alternating current generated by an engine output in an in-vehicle power supply system for an idle stop vehicle, and is charged by the output of the alternator. 1 in-vehicle battery, a rectifier that rectifies the output of the AC interphase voltage or single-phase voltage generated by the alternator n times (n is an integer of 2 or more), and charge acceptance performance higher than that of the first in-vehicle battery A second in-vehicle battery charged by the output of the rectifier, and an output regulator for stepping down an output taken out from the second in-vehicle battery to a voltage higher than that of the first in-vehicle battery, A vehicle load including an engine starter that outputs the output of the in-vehicle battery and the output of the second in-vehicle battery via the output regulator. It is characterized by parallel feed (claim 1).

  In the case of the in-vehicle power supply system according to the first aspect of the present invention, the AC interphase voltage or single-phase voltage generated output generated by the alternator is voltage-rectified n times by a rectifier separate from the rectifier of the alternator. Due to the rectified output of the voltage, the second in-vehicle battery is effectively charged with a high voltage in a short time and efficiently using the charge acceptance performance higher than that of the first in-vehicle battery.

  Further, the output of the second in-vehicle battery is extracted after being stepped down to a voltage higher than that of the first in-vehicle battery by an output regulator that performs only step-down adjustment during discharging (load feeding). And the output of the 1st vehicle-mounted battery charged with the rectification output of an alternator and the output of the 2nd vehicle-mounted battery via an output regulator are electrically fed in parallel to the vehicle load including the engine starter.

  When the engine is restarted from the idle stop state, the remaining energy is effectively taken out from the second vehicle-mounted battery charged to the fully charged state by the engine output before the idle stop by the step-down adjustment of the output regulator. The output voltage of the second in-vehicle battery that is stepped down by the output regulator is higher than the output voltage of the first in-vehicle battery. Therefore, the output of the second in-vehicle battery is preferentially supplied to a vehicle load such as a starter, and starter power supply for engine restart at idle stop is performed by the output of the second in-vehicle battery. When the first in-vehicle battery is a battery with low self-discharge, such as a lead-acid battery, the starter power supply during cold start is such that the first in-vehicle battery with less self-discharge than the second in-vehicle battery has a high voltage, Since the impedance is low, starter power feeding is automatically performed with the output of the first in-vehicle battery without providing a starter power source switching relay or the like of the conventional device.

  And the extraction of charging power from the alternator to the second in-vehicle battery and transmission of the extracted power can be performed efficiently with high voltage and small current of power generation AC with little loss, and the DC wiring diameter is reduced as in the conventional device. There is no need to make it thicker and it becomes cheaper. Therefore, the second in-vehicle battery can be efficiently charged with a configuration that is less expensive than the conventional system.

  In addition, instead of a bidirectional switching regulator (input / output regulator) 160 that performs both charge input adjustment and discharge output adjustment in the conventional system, an output regulator that performs only voltage drop adjustment during discharge may be provided. In addition, since the starter power supply switching relay 140 of the conventional system can be omitted, the cost is further reduced.

  Furthermore, the number of times of passage of elements such as diodes and FETs (switching elements) that cause the voltage drop of the second in-vehicle battery is reduced, and the charge / discharge loss is reduced. The failure probability is lowered and the reliability is improved.

  In addition, the rectifier capacity of the alternator may be a small capacity that covers the charging of the first in-vehicle battery, and there is an advantage that the cost is further reduced.

  Next, an embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows the configuration of the in-vehicle power supply system of this embodiment, and FIG. 2 shows the detailed configuration of the switching regulator 3 of FIG. 3 and 4 are operation explanatory diagrams of the in-vehicle power supply system of FIG.

  In FIG. 1, reference numeral 1 denotes a first in-vehicle battery (main battery) corresponding to the in-vehicle battery 100 in FIG. 6, and is composed of a 12 V lead storage battery similar to the in-vehicle battery 100. Reference numeral 2 denotes a second in-vehicle battery (auxiliary battery) having a lithium ion secondary battery configuration corresponding to the in-vehicle battery 130 in FIG. 6. For example, the series connection circuit 2b of two cells 2a having a terminal-to-terminal voltage of 14.6 V is set to 3 A parallel output of each serial connection circuit 2b (output which becomes 29, 2V when fully charged) is taken out.

  Reference numeral 3 denotes a switching regulator as an output regulator according to the present invention. As shown in FIG. 2, a switching regulator includes a one-mode control DC / DC controller 31 having a microcomputer configuration. A smoothing reactor 33 is formed in series with the discharge path of the second in-vehicle battery 2.

  The switching regulator 3 switches the FET 32 by the controller 31 based on the state of the second in-vehicle battery 2 and the voltage state of the load power supply path 4, and the switching regulator 3 based on the discharge energy of the second in-vehicle battery 2. The voltage of the DC output is controlled to a voltage slightly higher than the voltage of the first in-vehicle battery 1 and lower than the DC output of the alternator 11. In FIGS. 1 and 2, the charging path of the second in-vehicle battery 2 is indicated by a solid line arrow, and the discharging path is indicated by a broken line arrow.

  Further, the output of the first in-vehicle battery 1 and the output of the second in-vehicle battery 2 whose voltage is adjusted by the switching regulator 3 are supplied through various fuses 41 of the load power supply path 4 such as a headlamp and an air conditioner. Power is supplied to the electric load 5 in parallel and to the starter 6. This starter 6 corresponds to the starter 150 of FIG. 6, but the starter power supply switching relay 140 of FIG. 6 is omitted, so that the output of the first in-vehicle battery 1 and the second voltage adjusted by the switching regulator 3 are adjusted. The output of the in-vehicle battery 2 is always supplied in parallel.

  Then, at the initial start of the engine and at the subsequent restart of the idle stop, a start signal SS * similar to the start signal SS of FIG. 6 is sent via the switch 8 similar to the switch 200 of FIG. The coil 71 of the star relay 7 similar to the relay 190 is energized, the contact 72 of the star relay 7 is closed, and the starter 6 is excited.

  Next, reference numeral 9 in FIG. 1 denotes a vehicle key switch corresponding to the vehicle key switch 170 in FIG. 6, and the ignition contact 91 and the start contact 92 are turned on by the ignition-on operation. A vehicle control ECU 10 having a microcomputer configuration corresponding to the vehicle control ECU of FIG. 6 generates a start signal SS * when it recognizes engine start and restart from changes in contact signals of the contacts 91 and 92, and the like. .

  Reference numeral 11 denotes an alternator with a regulator corresponding to the alternator 210 of FIG. 5, and the generator unit 13 attached to the engine based on the control of the control circuit 12 having a microcomputer configuration for exchanging information with the vehicle control ECU 10 serves as the engine output. Therefore, U, V, and W three-phase alternating current is generated, and the generated output is supplied to a rectifier 14 formed by a three-phase full bridge of a plurality of diodes D to be full-wave rectified. Power is supplied to the first in-vehicle battery 1.

  Reference numeral 15 denotes a rectifier according to the present invention. An AC interphase voltage or a single-phase voltage output generated by the generator unit 13 of the alternator 11 is multiplied by n times (n is an integer of 2 or more) by half-wave rectification of each diode 16. Rectification is performed, and the second in-vehicle battery 2 is charged with the rectified output. Specifically, in the case of the present embodiment, the voltage between each phase of U and V, V and W, W and U taken out from the generator unit 13 is double-voltage rectified (n = 2), and the second in-vehicle battery The two cells 2a of each of the two serial connection circuits 2b are charged. Therefore, for example, with respect to the interphase voltage between U and V, when the U phase becomes a positive voltage, one cell 2a of the corresponding series connection circuit 2b is charged by the rectified output of the diode 16 whose anode is connected to the U phase, and V When the phase becomes positive voltage, the other cell 2a of the series connection circuit 2b is charged by the rectified output of the diode 16 whose cathode is connected to the U phase, and the series connection circuit 2b is charged by voltage doubler rectification. Similarly, the inter-phase voltage of V and W and the inter-phase voltage of W and U are similarly charged by the voltage doubler rectification. By charging the voltage doubler rectified output, the second in-vehicle battery 2 is charged to, for example, 29.2V described above. Note that the second in-vehicle battery 2, the switching regulator 3, and the rectifier 15 are actually formed by an auxiliary battery unit 17 with a voltage doubler rectifier circuit, which is a single component. Further, 18 in FIG. 1 is the same charging warning light as the charging warning light 220 in FIG.

  Therefore, during engine operation such as when the vehicle is running, the first in-vehicle battery 1 is gradually charged to about 12 V by the rectified output of the rectifier 14 of the alternator 11 as in the in-vehicle battery 100 of the conventional device. On the other hand, the second in-vehicle battery 2 is efficiently charged to a high voltage (29.2 V) in a short time by an output obtained by voltage rectifying the three-phase AC power generation output of the generator unit 13 of the alternator 11 with the rectifier 15.

  When the engine is restarted at idle stop (warm start), the output voltage of the switching regulator 3 based on the discharge energy of the second in-vehicle battery 2 is higher than the voltage of the first in-vehicle battery 2, and the starter of the conventional system Even without the power supply switching relay 140 or the like, the discharge energy of the second in-vehicle battery 2 is automatically supplied to the starter 6 and the engine is restarted.

  Next, a specific charging / discharging operation of the in-vehicle power supply system of FIG. 1 will be described with reference to FIGS. 3 and 4, the rectifier 15 between the alternator 11 and the second in-vehicle battery 2 is omitted.

  First, at the time of the first cold start from the parking state or the like, the voltage of the first in-vehicle battery 1 with less residual energy in the second in-vehicle battery 2 and less self-discharge becomes higher than the voltage of the switching regulator 3. Therefore, the discharge energy of the first in-vehicle battery 1 is preferentially supplied to the starter 6, and based on this supply, the starter 6 rotates according to the start signal SS * to start the engine. At this time, the first in-vehicle battery 1 is discharged.

  During the idle state immediately after the engine is started, the first in-vehicle battery 1 is charged by the rectified output (output of the rectifier 14) of the alternator 11 indicated by arrows α and β in FIG. 5 power supply is covered. Moreover, the 2nd vehicle-mounted battery 2 is charged by the double voltage rectification output of the alternating current (three-phase alternating current of the generator part 13) of the alternator 11 shown by the arrow line (gamma) of the same figure (a). At this time, the first in-vehicle battery 1 seems to be deeply discharged due to standby power consumption and energy consumption for starting the engine, but charging does not proceed due to low charge acceptability. On the other hand, the second in-vehicle battery 2 with high charge acceptance performance is quickly charged even if it is completely discharged by self-discharge. For this reason, the in-vehicle batteries 1 and 2 immediately after the engine is started are in a charged state indicated by, for example, a hatched line in FIG. 3 and 4, the upward arrow line on the left side of the second in-vehicle battery 2 indicates that the in-vehicle battery 2 is in a charged state.

  Next, when the vehicle travels, the power generation amount of the alternator 11 rises due to surplus energy of the engine based on acceleration and deceleration during traveling, and the vehicle is mounted by the rectified output and power generation AC of the alternator 11 as shown in FIG. Each of the batteries 1 and 2 is charged, and the rectified output of the alternator 11 supplies power to the electric load 5. At this time, although the apparent voltage of the first in-vehicle battery 1 increases due to the increase in the amount of power generated by the alternator 11, there is little increase in the actual remaining energy (stored energy), and it takes time to fully charge. On the other hand, the second in-vehicle battery 2 has a high charging voltage and a high charge acceptance performance, and thus reaches a fully charged state of a high voltage (for example, 29.2 V) in a short time.

  Next, when the travel stops with the setting that the idle stop does not work and the engine returns to the idle state, the second in-vehicle battery 2 is in a fully charged state as shown in FIG. 3 (c). As shown by the arrow lines α and β in (c), charging of the first in-vehicle battery 1 and feeding of the electric load 5 by the rectified output of the alternator 11 are performed. At this time, since the power generation amount of the alternator 11 is small in the idle state, the first in-vehicle battery 1 does not easily reach a fully charged state if the electric load 5 is large and the load is heavy. In addition, arrow line (gamma) and x mark of FIG.3 (c) show that the charging current is not inject | poured when the 2nd vehicle-mounted battery 2 is a full charge state. Even when the engine output (power) decreases to the idle state and the power generation amount of the alternator 11 decreases, the second in-vehicle battery 2 is already in the charged state, and thus is maintained in the fully charged state.

  Next, a case where the vehicle travels with the idle stop set will be described.

  First, when an idle stop state is caused by a red signal or the like, the engine output is turned off, and the power generation AC and rectification output of the alternator 11 are also turned off. At this time, as shown in FIG. 4A, even if the first in-vehicle battery 1 is not fully charged, the second in-vehicle battery 2 is in a fully charged state by the previous charging. Since the output voltage of the switching regulator 3 is controlled to be slightly higher than the voltage of the first in-vehicle battery 1, the discharge energy of the second in-vehicle battery 2 is changed to the switching regulator as shown by an arrow line δ in the figure. Power is preferentially supplied to the electric load 5 via 3. This is because the energy of the second in-vehicle battery 2 with high charge acceptance performance and high charge / discharge efficiency is positively used to increase the use efficiency of the engine output, and finally the fuel efficiency of the vehicle is improved. It is for aiming at. Therefore, the switching regulator 3 adjusts, for example, the output voltage to be a target voltage (for example, 12.5 V) set so that the first vehicle-mounted battery 1 is neither charged nor discharged. Alternatively, the output voltage of the switching regulator 3 during the idle stop may be adjusted by measuring the voltage of the load power supply path 4 immediately before the idle stop and predicting the remaining power amount of the in-vehicle battery 1.

  Next, when the idling stop is completed by changing from a red signal to a blue signal and the engine is restarted (warm restart), the second in-vehicle battery 2 has a remaining amount due to load power supply during idling stop. Even if the energy is reduced, the voltage is high (29.2V) because it is charged by voltage doubler rectification. Therefore, the switching regulator 3 can sufficiently use the remaining energy of the second in-vehicle battery 2 having a high deep discharge tolerance, and can supply the load power supply path 4 with a direct current sufficient to start the starter 6. Therefore, as shown in FIG. 4B, the power supply from the second in-vehicle battery 2 indicated by the solid line arrow δ has priority over the power supply from the first in-vehicle battery 1 indicated by the solid line arrow ε. The starter 6 is rotated by the discharge energy, and the engine is restarted. At this time, the impedance of the switching regulator 3 is low, and the discharge energy of the second in-vehicle battery 2 is reliably supplied to the starter 6 and the like without using the conventional starter power supply switching relay 140 and the like.

  If the power consumption of the starter 6 and the electric load 5 cannot be covered only by the power supply from the in-vehicle battery 2, energy is also taken out from the in-vehicle battery 1 due to the voltage drop.

  In the case of the in-vehicle power supply system of the present embodiment, the charging transmission path from the alternator 11 to the rectifier 15 in order to extract and transmit power to the second in-vehicle battery 2 by the three-phase AC of the power generation output of the alternator 11. Is a high voltage and a small current, has little loss, and the transmission efficiency of charging the second in-vehicle battery 2 is dramatically improved over the conventional system. Further, it is not necessary to increase the wiring diameter, and the cost can be reduced. Furthermore, since the switching regulator 3 is configured to operate in a single mode that only performs step-down adjustment during discharging, the configuration is simpler than the bidirectional type that operates in a plurality of modes of charging and discharging, and the impedance to the passing current Is low and further cost reduction can be achieved.

  Further, the rectifier 15 has a diode half-wave rectification configuration. Further, since the charging current of the second in-vehicle battery 2 does not pass through the rectifier 14 or the switching regulator 3, the second in-vehicle battery 2 is charged and discharged. The number of times a charging current or discharging current passes through an element such as a diode or FET that sometimes causes a voltage drop is smaller than that of the conventional system, and there is less loss, and the failure probability of the charging / discharging path is reduced, thereby improving the reliability.

  Furthermore, it is the structure which carries out parallel electric power feeding of the output of the vehicle-mounted battery 1 and 2 to the load electric power feeding path 4, and it replaces with the bidirectional | two-way switching regulator 160 which performs both the input adjustment of charge of the conventional system, and the output adjustment of discharge. The voltage drop regulator 3 only needs to be provided in one stage, and the starter power supply switching relay 140 that is essential in the conventional system is unnecessary due to the low impedance effect by the voltage drop means (FET 32 and reactor 33) of the voltage drop regulator 3 in one stage. Therefore, the diameter of each power supply wiring can be reduced, the number of parts is small, and the manufacturing work is facilitated.

  Next, each cell 2a of the second in-vehicle battery 2 is divided into three sets of two by the rectifier 15 of voltage doubler rectification, and the two cells 2a of each set are divided into three types of phases different for each set. For example, even if one set fails, charging and discharging can be performed with the other two sets, and the reliability is further improved.

  Furthermore, the charge boosting loss energy of the second in-vehicle battery 2 becomes unnecessary, and the rectifier capacity of the alternator 11 may be a small capacity that covers the charging of the first in-vehicle battery 1 and the capacity of the second in-vehicle battery 2 is small. Therefore, the idle stop system can be reduced in size and cost can be further reduced.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, the second in-vehicle battery 2 is Various secondary batteries with high charge acceptance performance other than the nickel-hydrogen battery may be used, and further, the battery may be constituted by a capacitor such as a so-called large-capacity capacitor. Moreover, the 1st vehicle-mounted battery 1 may be a secondary battery with little self-discharge amount other than a lead acid battery.

  Further, the configuration of the switching regulator 3 and the rectifier 15, the number of cells of the second in-vehicle battery 2, the charging voltage, and the like are not limited to those of the above embodiment.

  Next, in the embodiment, the generator unit 12 of the alternator 11 has a three-phase structure, and the second in-vehicle battery 2 is charged by the voltage doubler rectified output of each interphase voltage of the generator unit 12 by the rectifier 15. Of course, the rectifier 15 may be formed into a voltage rectifier of 3 times, 4 times,..., And the second vehicle-mounted battery 2 may be charged by a double voltage rectified output of 3 times, 4 times,. Further, for example, a single-phase voltage (line voltage) may be taken out from the generator unit 12 of the alternator 11, and the second in-vehicle battery 2 may be charged by rectifying the voltage n times. In the case of charging by voltage doubler rectification (n = 2), for example, a rectifier 15 * having a configuration shown in FIG. In the figure, 2c is a cell divided into two sets of the second in-vehicle battery 2, and 16 * is a positive and negative rectifier diode of the rectifier 15 *.

  And this invention is applicable to the vehicle-mounted power supply system of various idle stop vehicles.

It is a connection diagram of the vehicle-mounted power supply system of one Embodiment of this invention. FIG. 2 is a detailed connection diagram of the switching regulator of FIG. 1. It is explanatory drawing of the charging / discharging operation | movement of FIG. It is another explanatory view of the charge / discharge operation of FIG. It is a connection diagram of the other example of the rectifier of this invention. It is a connection diagram of a conventional system. FIG. 7 is a detailed connection diagram of a part of FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st vehicle-mounted battery 2 2nd vehicle-mounted battery 3 Switching regulator (output regulator)
6 Starter 11 Alternator 15, 15 * Rectifier

Claims (1)

In the in-vehicle power supply system for idle stop cars,
An alternator that rectifies and outputs AC generated by engine output;
A first in-vehicle battery charged by the output of the alternator;
A rectifier for voltage rectifying the output of the AC interphase voltage or single-phase voltage generated by the alternator n times (n is an integer of 2 or more);
A second in-vehicle battery having higher charge acceptance performance than the first in-vehicle battery and charged by the output of the rectifier;
An output regulator for stepping down the output taken from the second in-vehicle battery to a voltage higher than that of the first in-vehicle battery;
An in-vehicle power supply system, wherein the output of the first in-vehicle battery and the output of the second in-vehicle battery via the output regulator are fed in parallel to a vehicle load including a starter of the engine.

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