JPH0564007U - Vehicle power supply - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to supply the specified voltage even during engine startup. A battery 1 provided in a vehicle, a first load circuit 8 that is supplied with electric power from the battery 1, and a second load circuit 9 that also consumes less power than the first load circuit 8. A voltage holding circuit 10 is provided that supplies power of a predetermined voltage only to the second load circuit 9 when the supply voltage from the battery 1 drops below a predetermined value.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vehicle power supply device having a starting motor.

[0002]

[Prior Art]

 It is known that when the engine is started, the voltage of the battery temporarily drops due to the operation of the starting motor, and particularly when the engine is started in cold weather, the voltage of the battery drops to less than half the specified value.

As a device for preventing malfunction of electronic equipment mounted on a vehicle due to the temporary voltage drop of the battery, for example, as disclosed in Japanese Utility Model Publication No. 3-33566, The first and second constant voltage circuits are provided, and the output voltage of the second constant voltage circuit is changed to the second constant voltage circuit only when the output voltage of the second constant voltage circuit becomes lower than the output voltage of the first constant voltage circuit. (1) A power supply device having a backup circuit that makes the output voltage of the constant voltage circuit approximately equal is known, and is used for securing a storage holding voltage of a storage device that holds data for controlling an engine.

[0004]

[Problems to be solved by the device]

 However, in the above power supply device, if the output voltage of the first constant voltage circuit becomes lower than the specified voltage of the battery when the engine is started, the output voltage of the second constant voltage circuit also becomes less than the supply voltage of the battery, and the output voltage of the brake monitor, etc. As for the safety device, there was a problem that the operation during starting was not guaranteed for the load circuit that always required the specified voltage.

Therefore, an object of the present invention is to provide a power supply device for a vehicle, which can supply a prescribed voltage even when the engine is started.

[0006]

The present invention provides a power supply circuit provided in a vehicle, a first load circuit that receives power from the power supply circuit, and a power consumption circuit that consumes more power than the first load circuit. A second load circuit with low power and a voltage holding circuit that supplies power of a predetermined voltage only to the second load circuit when the supply voltage from the power supply circuit drops below a predetermined value.

[0007]

[Action]

 When the voltage of the power supply circuit drops, the voltage holding circuit outputs a predetermined voltage set in advance, and the second load circuit receives the supply of the predetermined voltage from the voltage holding circuit and operates normally. The load circuit of No. 1 receives the reduced voltage from the power supply circuit.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a battery provided in a vehicle and having a negative electrode grounded, 2 is a generator driven by an engine (not shown), 3 is a starter switch that operates in conjunction with an ignition key (not shown) of the vehicle, 4 Is a starting motor that starts an engine (not shown) by opening and closing the starter switch 3, and is driven by the electric power of the battery 1.

Reference numeral 8 denotes a first load circuit that requires a specified voltage only when the engine is operating, and is driven by the battery 1 and is composed of, for example, a lighting circuit.

Reference numeral 9 is a second load circuit that always requires a prescribed voltage, and is constituted by, for example, a brake monitor or the like, and requires the prescribed voltage of the battery even during low voltage such as during engine start.

Reference numeral 5 denotes a forward direction from the first load circuit to the second load circuit, a diode connecting these load circuits, 6 is an auxiliary battery whose negative electrode is grounded, and 7 is a diode between the diode 5 and the second load circuit. Is a constant voltage circuit which is interposed in the forward direction of the diode 5 and is supplied with electric power from the auxiliary battery 6, and the voltage holding circuit 10 composed of these supplies a predetermined voltage to drive the second load circuit 9. To do.

That is, the first load circuit 8 is driven by the battery 1 or the generator 2, and the second load circuit is driven by the battery 1, the generator 2 or the auxiliary battery 6.

The constant voltage circuit 7 is composed of, for example, a switching regulator or a series regulator, and can be composed of a shunt regulator or the like when the power consumption of the second load circuit is low.

The auxiliary battery 6 is composed of a secondary battery, for example, a lead storage battery or a nickel cadmium battery, and can be charged by the battery 1 or the generator 2.

With the above-mentioned configuration, the operation will be described.

At the time of starting the engine (not shown), when the starter switch 3 is operated, the starting motor 4 cranks the engine by the electric power of the battery 1.

At this time, since the starting motor 4 consumes a large amount of power, the supply voltage of the battery 1 temporarily drops, and the generator 2 supplies sufficient power at the rotation speed during cranking. Therefore, the voltage supplied to the first load circuit 8 and the diode 5 becomes lower than the specified voltage.

Although the auxiliary battery 6 maintains the specified voltage, the current flowing toward the starting motor 4 and the first load circuit 8 whose voltage has been lowered by the diode 5 does not flow to the constant voltage circuit 7. Only the specified voltage is supplied, and the second load circuit 9 receives the specified voltage of the constant voltage circuit 7 and operates normally.

On the other hand, when the engine starts and enters a normal operating state, the starter switch 3 is cut off and the starting motor 4 stops, and the generator 2 starts supplying electric power to the first load circuit 8. Supply the specified voltage, and if the battery 1 is below the specified voltage, start charging.

When the supply voltage exceeds the voltage of the auxiliary battery 6, the generator 2 supplies electric power to the constant voltage circuit 7 to drive the second load circuit 9 and charge the auxiliary battery 6. The auxiliary battery 6 can always supply the specified voltage.

Therefore, the second load circuit is normally driven by the specified voltage of the auxiliary battery 6 through the constant voltage circuit 7 even if the voltage drop of the battery 1 occurs during engine start or the like, and the diode 5 Prevents the power supply to the first load circuit 8 and the starting motor 4 of the auxiliary battery 6 to prevent the voltage drop of the auxiliary battery 6, and further, when the engine is operating normally, the auxiliary battery 6 is used by the generator 2. Since the battery 6 is charged and the second load circuit 9 is driven, the auxiliary battery 6 can generate a specified voltage at the next engine start without discharging.

FIG. 2 shows another embodiment, in which a capacitor 61 is connected instead of the auxiliary battery 6 in the first embodiment, and other configurations are the same as those in the first embodiment.

Therefore, when the voltage of the battery 1 drops during engine startup, the second load circuit is normally driven by the discharge of the capacitor 61 via the constant voltage circuit 7, and the diode 5 is connected to the first of the capacitor 61. 1 The power supply to the load circuit 8 and the starting motor 4 is blocked to prevent the voltage drop of the capacitor 61. Furthermore, in the normal operating state of the engine, the generator 2 charges the capacitor 61 and the second load. Since the circuit 9 is driven, the capacitor 61 can generate a specified voltage during the next engine start without discharging.

FIG. 3 shows still another embodiment, in which the voltage holding circuit 10 is connected to the battery 1 to drive the second load circuit 9, and the step-up controllable switching regulator 71 and the voltage of the battery 1 are regulated. The voltage monitor circuit 62 switches the switching regulator 71 to the boost control when the voltage drops below the voltage of (1). The other configuration is the same as that of the first embodiment.

The voltage monitor circuit 62 switches the switching regulator 71, which normally performs step-down control, to step-up control when the voltage of the battery 1 drops below a predetermined value during engine startup or the like, and sets the dropped voltage to a specified value. The voltage is boosted to drive the second load circuit 9.

[0027]

[Effect of the device]

 As described above, according to the present invention, even if the voltage of the power supply circuit is lowered during engine startup, the second load circuit is normally driven by the regulated voltage supplied by the voltage holding circuit. If the load circuit is composed of a safety device such as a brake monitor, there is an effect that it can always operate properly.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

[Explanation of symbols]

 2 Generator 4 Starting Motor 6 Auxiliary Battery 7 Constant Voltage Circuit 8 First Load Circuit 9 Second Load Circuit 10 Voltage Holding Circuit

Claims (1)

[Scope of utility model registration request] 1. A power supply circuit provided in a vehicle, a first load circuit that receives power from the power supply circuit, and a second load circuit that consumes less power than the first load circuit.
And a voltage holding circuit that supplies power of a predetermined voltage only to the second load circuit when the supply voltage from the power supply circuit drops below a predetermined value. apparatus.