JPH01170334A - Battery charger for vehicle - Google Patents

Abstract

PURPOSE:To cope with the overdischarge of a main battery by charging the main battery and an auxiliary battery having a small capacity by a generator when both the batteries are not overdischarged, and raising the voltage of the auxiliary battery by a converter thereby to charge it when the main battery is overdischarged. CONSTITUTION:A generator 3 charges a main battery 2 during the operation of an engine, and charges an auxiliary battery 101 having a small capacity through switches 4, 110 and a diode 102. When the battery 2 is overdischarged and the generator 3 is not started at the time of starting the engine, a switch 104 of the battery 101 is continuously pressed. A control circuit 112 outputs to fire an LED 108 thereby to energize a Tr circuit 115, to close a switch 6, to apply the voltage of the battery 101 to a DC/DC converter 107, to raise the voltage, and to apply it to the terminal of the battery 2, thereby starting the engine. Thus, even if the main battery is overdischarged, the engine is immediately started.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle battery charging device useful when a vehicle battery is over-discharged.

[Conventional technology]

Conventional battery charging devices charge the battery by connecting the battery charging device to both terminals of the battery when the battery runs out due to overdischarge.

[Problem that the invention seeks to solve]

However, since conventional battery charging devices are always disconnected from the battery, there is a delay in responding when the battery becomes over-discharged, and it is necessary to always keep a large capacity charging device in a sufficiently charged state in advance. Problems such as the troublesomeness of holding the charging device have arisen.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vehicle battery charging device that can be charged immediately when a battery is over-discharged, has high charging efficiency, and does not require any troublesome maintenance.

[Means for solving problems]

In order to solve the above problems, the present invention includes a main battery that is charged by a generator driven by an internal combustion engine, and an auxiliary battery that has a smaller capacity than the main battery.
When the main battery is not over-discharged, the main battery and the auxiliary battery are charged by the generator, and when the main battery is over-discharged, the voltage of the auxiliary battery is boosted by the converter to charge the main battery. The configuration includes a control means.

[Effect]

According to the above configuration, when the main battery is not in an over-discharge state, the main battery and the auxiliary battery are charged by the generator driven by the internal combustion engine, and the main battery performs, for example, starting the internal combustion engine. In addition, when the main battery is over-discharged, the voltage of the auxiliary battery is boosted by the converter and the main battery is charged, so the energy stored in the auxiliary battery is efficiently transferred to the main battery, and the main battery is over-discharged. can be resolved satisfactorily.

〔Example〕

FIG. 1 shows an electrical circuit diagram of a vehicle battery charging device of the present invention. This embodiment includes a vehicle battery charger 1, a vehicle battery 2 which is a main battery, and an alternator 3 which is a generator.
, an ACC switch 4 and a light switch 5 which are accessory switches. The vehicle battery charger l is installed in a normal engine room (not shown), and the auxiliary battery built in this vehicle battery charger l is installed in a normal engine compartment (not shown).
For example, the NP4-12 (manufactured by Yusenbattery) has a smaller capacity than the main battery, and is charged by the alternator 3 through the ACC switch 4, diode 102, and high voltage protection circuit 110 while the engine is starting, and is always fully charged in case of an emergency. The structure is maintained.

Each element of the battery charger 1 of this embodiment will be described in detail below.

A transistor circuit 111 and a diode 103A.

B is to turn on the light switch 5 and ACC switch 4.

It is provided as a level shifter for notifying the control circuit 112 that it is OFF. In addition, the transistor circuit 113
The diode 103C is provided as a level shifter for notifying the control circuit 112 of the connection state to the vehicle battery 2. Furthermore, the transistor circuit 117 and the diode 103D are connected to the interlocking switch (momentary) 104.
The control circuit 112 is provided as a level shifter for notifying the control circuit 112 of the ON/OFF state of the signal.

The transistor circuit 114 and the diode 103E are
It is provided as a booster circuit for turning on and off the supply of power to the voltage regulator 105 based on the output of the control circuit 112.

The transistor circuit 115 is provided as a booster circuit for turning on and off the relay 106 based on the output of the control circuit 112. Power from the auxiliary battery 101 is supplied by a relay 106 to a DC/DC converter, which will be described later.

A voltage comparator built into the resistance circuit 116 and the control circuit 112 is provided to compare the terminal voltage of the auxiliary battery 101 with a reference voltage and monitor the state of charge.

The high voltage protection circuit 110 uses a relay 110A to prevent the auxiliary battery 101 from being overcharged and damaged when this device is connected to a 24V vehicle battery.
This is a circuit that protects 1.

DC/DC converter 1 for step-up which is a converter
07 (for example, a circuit using μA78S40) is a circuit that boosts and discharges the terminal voltage of the auxiliary battery IO1 when discharging to the vehicle battery 2.

The control circuit 112 operates according to a predetermined program.
This circuit executes digital arithmetic processing using software, and includes a CPU, ROM, RAM, 110 circuit section, clock generation section, etc., and receives a stable voltage of 5V from the auxiliary battery 101 via the voltage regulator 105, and performs arithmetic processing. Executes and outputs a signal. The LED loB is provided to light up or blink based on the output of the control circuit 112 to indicate the operating state of the device.

The operation of the above configuration is shown in FIG.

The explanation will be given according to the flowchart.

When the driver confirms that the main battery 2 is over-discharged, such as when starting the engine, if the driver continues to press the interlock switch 104, the power is turned on to the circuit of the charging device (step 201). After the power is turned on, the process proceeds to step 202, where the registers, memory, etc. in the control circuit 112 are initialized. Next, proceeding to step 203, the transistor circuit 11
Detect the output of 3 and check whether it is connected to the vehicle battery. If the wires are connected, go to step 2゜4.
If the wires are not connected, the process returns to input in step 203.

In step 204, the state of the "PWR" flag and the fall of the output of the transistor circuit 117 are detected, and if both are satisfied, the process proceeds to step 213. If the interlock switch 104 is released in this state, the power supply to the circuit is stopped. If the condition in step 204 is not met, the process proceeds to step 205. In step 205, the ON/OFF states of the ACC switch 4 and the light switch 5 are determined based on the output of the transistor circuit 111. If at least one of the switches is ON, the process proceeds to 215, and if both are OFF, the process proceeds to 206. .

In steps 206 and 215, the internal clock timer determines whether one second has elapsed since the power was turned on.
If one second has elapsed, the process proceeds to the next step, and if it has not elapsed, the process returns to step 2050 input. This one
The purpose of the second waiting time is to prevent the power from being turned on even if the interlocking switch 104 is pressed due to some kind of erroneous operation. In step 207, the "PWR" flag is set, and in step 208, the voltage is output from the output of the control circuit 112 to the booster circuit 114. From this point on, even if the interlock switch 104 is turned off, the power of the auxiliary battery 101 is sent to the circuit. Supplied. Next step 209
The control circuit 112 turns the relay 106 ONL, D C/D.
Power from the auxiliary battery 101 is supplied to the C converter 107, and the vehicle battery 2 is charged. At this time, the terminal voltage of the auxiliary battery lot is monitored in step 201.

That is, a comparator built into the resistance circuit 116 and the control circuit 112 determines whether the terminal voltage of the auxiliary battery 101 is below IOV or above 12V in this example. 10■ or less, that is, if it is determined that the auxiliary battery 101 is in an over-discharge state, step 213
, and charging is stopped. On the other hand, if it is being charged at 12V or more, it is determined that the internal impedance of the vehicle battery 2 is high (the vehicle battery is defective), and the process proceeds to step 214, where the LED 108 blinks at a frequency of about 2Hz, indicating abnormal charging. Let me know.

If the terminal voltage of the auxiliary battery 101 is within the range of IOV to 12V, the process advances to step 211, and the LEDlo
B blinks at a frequency of about IHz to let you know that it is being charged normally. The charging time is determined by step 212. In this case, after 5 minutes have passed after the power is turned on, the process advances to step 213 and charging is stopped. If 5 minutes have not elapsed, the process returns to step 203.

Next, if at least one of the ACC switch 4 and the light switch 5 is turned on in step 205, the process proceeds to step 215 as described above. Steps 216 and 217 represent operations similar to steps 207 and 208, respectively. In step 218, LED loB is lit to warn that the ACC switch 4 and light switch 5 have been forgotten to be turned off. In step 219, LED 10
Determine the lighting time of B. In this case, after turning on the power,
If it is within seconds, the process returns to step 219, and if it exceeds 5 seconds, it proceeds to step 213 and stops.

In the above configuration, a microcomputer is used as the control circuit 112, but a configuration using hard logic is also possible. Furthermore, although LED loB is used for display, warnings using voice synthesis or the like are also possible.

Furthermore, in step 210 of the above flowchart,
By making it possible to detect 11.5V, it is also possible to detect the fully charged state of the auxiliary battery 101.

In the embodiment described above, the over-discharge state of the main battery 2 was checked when the driver started the engine, but it may be automatically detected by a control circuit or the like.

By employing this embodiment as described above, when the vehicle battery 2 is over-discharged, the electric energy of the auxiliary battery 101 charged by the alternator 3 can be efficiently and quickly transferred via the converter 107. Not only can you transfer it, but you can also get the following effects.

(1) Since the charging of the vehicle battery can be automatically stopped based on the set time or the auxiliary battery terminal voltage, over-discharge of the auxiliary battery can be prevented.

(2) When the vehicle ACC or light switch is turned on,
Since charging of the vehicle battery from the auxiliary battery is stopped, the vehicle battery can be efficiently charged.

(3) In order to protect the auxiliary battery, when a vehicle battery with a steady voltage different from that of the auxiliary battery is connected to the battery charging device, charging of the auxiliary battery can be automatically stopped.

(4) Furthermore, although the vehicle battery charging device of this embodiment is normally mounted on a vehicle while connected to the main battery, in the event of an emergency involving another vehicle such as over-discharging of the main battery of another vehicle,
It can also be used as a portable battery charging device.

〔Effect of the invention〕

By adopting the present invention, the vehicle battery charging device of the present invention is constantly charged by the generator driven by the internal combustion engine, so there is no need to worry about holding the charging device, and furthermore, the vehicle battery charging device of the present invention is constantly connected to the battery. Therefore, it is possible to immediately respond to over-discharge of the battery. Furthermore, since the voltage of the auxiliary battery is boosted by the converter, the electrical energy of the auxiliary battery can be efficiently (and quickly) transferred to the main battery.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of a vehicle battery charging device according to the present invention, and FIG. 2 is a flowchart showing the operation of the embodiment. l...Vehicle battery charger, 2...Main battery (
vehicle battery), 3... alternator (8 generators). 101... Auxiliary battery, 106... Relay, 11
2...Control circuit.

Claims (1)

[Scope of Claims] A main battery charged by a generator driven by an internal combustion engine, an auxiliary battery having a smaller capacity than the main battery, and when the main battery is not over-discharged, the main battery and the auxiliary battery are A vehicle for use in a vehicle, characterized by comprising a control means for charging a battery by the generator, and for charging the main battery by boosting the voltage of the auxiliary battery by a converter when the main battery is over-discharged. Battery charging device. (2) The battery according to claim 1, wherein the control means stops charging the main battery from the auxiliary battery when the voltage of the auxiliary battery drops below a reference value. Charging device. (3) When the auxiliary battery is charging the main battery, the control means stops charging the auxiliary battery to the main battery after a certain period of time has elapsed from the start of charging. Battery charging device as described in section. (4) The control means enables charging of the main battery from the auxiliary battery only when the main battery and the auxiliary battery are connected. The battery charging device according to any one of Item 3. (5) The control means enables charging of the main battery from the auxiliary battery only when both an accessory switch and a light switch of the vehicle are OFF. 4. The battery charging device according to any one of items 4 to 4. (6) Claims 1 to 5, wherein the control means stops charging the auxiliary battery when the steady voltage of the auxiliary battery and the steady voltage of the main battery are different. Any of the battery charging devices described above.