JP2564199Y2 - Auxiliary power supply for vehicle - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular auxiliary power supply device used to obtain power for a plurality of vehicular electric appliances from a cigarette lighter socket provided in a vehicle.

[0002]

2. Description of the Related Art In recent years, electric appliances such as a television receiver and a CD player have been frequently used in the interior of an automobile. However, a power supply for such electric appliances is provided on a dashboard of the automobile. It is generally obtained from a cigarette lighter socket. In this case, since only one cigarette lighter socket is provided in an automobile, an auxiliary power supply device for obtaining a power supply for a plurality of electric appliances is practically used.

[0003] That is, this kind of auxiliary power supply device is configured to include a plug connected to a cigarette lighter socket and a plurality of sockets branched from the plug. In this case, in the conventional auxiliary power supply, a plurality of current fuses are provided corresponding to each socket for overcurrent protection.

[0004]

In the above-mentioned conventional configuration, when an excessive load current flows and the current fuses are blown, the fuses must be replaced one by one, and the maintenance becomes troublesome. is there. Further, the cigarette lighter is generally configured to be usable even when the engine is stopped, whereas the auxiliary power supply device is capable of connecting a plurality of electric appliances and consumes relatively large power. In many cases, the capacity of the vehicle-mounted battery may be inadvertently reduced, and in some cases, the engine may not be able to be started.

[0005] The present invention has been made in view of the above circumstances, and its object is to ensure the protection operation against overcurrent and to simplify the maintenance, and to prevent the abnormal consumption of the power supply beforehand. Another object of the present invention is to provide a vehicular auxiliary power supply device having the above effects.

[0006]

In order to achieve the above object, the present invention provides a vehicle auxiliary power supply having a plug connected to a cigarette lighter socket and a plurality of sockets branched from the plug. Current detection means for detecting a load current flowing through the socket, and overcurrent protection means for cutting off a current path to the socket when a state in which the load current detected by the current detection means exceeds a set value continues for a predetermined delay time or more. In addition, under voltage protection means for interrupting the current path to the socket when the input voltage has fallen below the set lower limit voltage for a predetermined delay time or more is provided.

[0007]

The load current flowing through the socket is detected by the current detecting means.
Only when the detected load current exceeds the set value for a predetermined delay time or more, the current path to the socket is cut off. Therefore, when an excessively large load current temporarily flows, the operation of interrupting the current path to the socket is not performed. Further, when the state in which the input voltage falls below the set lower limit voltage continues for a predetermined delay time or more, the undervoltage protection means cuts off the current path to the socket. Accordingly, there is no possibility that the power supply voltage may drop abnormally, and even if there is a temporary drop in the power supply voltage such as when starting the engine, the above-described energization path cutoff operation is not erroneously performed. .

[0008]

In FIG. 2 showing the entire appearance, a connecting plug 3 connected to a not-shown cigarette lighter socket (not shown) provided in an automobile by inserting it into a leading end of a power cord 2 led out of a main body case 1 is shown. Is provided. The main body case 1 is provided with three sockets 4 to 6 opened on the front side in a line.
6 to 6 can be plugged in and connected to electrical equipment for vehicles. The sockets 4 and 5 are provided with lids 1a and 1b for opening and closing them. On the front surface of the main body case 1, for example, a green light emitting diode 7 indicating that the sockets 4 to 6 are available, and a display indicating that the sockets 4 to 6 are unavailable are provided. A red light emitting diode 8 is provided.

FIG. 1 shows an electric circuit configuration, which will be described below. That is, the connection plug 3 has a pair of terminals 3a and 3b, and one of the terminals 3a
Is connected to the positive terminal of the on-vehicle battery 11 via the main fuse 9 and the ACC switch 10, and the other terminal 3
b is connected to the ground terminal. In addition, in-vehicle battery 1
The negative terminal 1 is also connected to the ground terminal.

The sockets 4 to 6 also have a pair of terminals 4a to 4a.
6a, 4b-6b, and each one terminal 4a-4
6a is connected to the normally open contact NO of the relay switch 12a, and the other terminals 4b to 6b are connected to ground terminals. The light emitting diode 7 has an anode connected to a relay switch 12 via a diode 13 having the polarity shown in the figure.
a is connected to the normally open contact NO, and the cathode is connected to the ground terminal via the resistor 14. The light emitting diode 8 has an anode connected to the normally closed contact NC of the relay switch 12a via a diode 15 having the illustrated polarity, and a cathode connected to the ground terminal via the resistor 14.

A sampling resistor 16 as current detecting means is connected between the common contact CM of the relay switch 12a and the terminal 3a. Here, ACC switch 1
When the contacts between the contacts (CM-NO) of the relay switch are turned on in the ON state of 0, the sampling resistor 16 and the contacts (C
The load current is supplied through the interval between M and NO). Therefore, the load current flowing through the sockets 4 to 6 can be detected based on the voltage across the sampling resistor 16.

The relay coil 12 of the relay switch 12a
b has one end connected to the terminal 3 a and the other end connected to the collector of the npn transistor 17. The transistor 17 forms a part of the relay drive circuit 18. The relay drive circuit 18 will be described below.

That is, the transistor 17 is in a state in which the resistor 19 is connected between the base and the emitter. The emitter is connected to the ground terminal via the resistor 20 and the base is connected via the resistor 21. Connected to terminal 3a. An npn-type transistor 22 is connected to both ends of the resistor 19.
The resistor 23 is connected between the base and the emitter of the transistor 22. The base of the transistor 22 is connected to the resistors 24, 2
5 is connected to the normally closed contact NC of the relay switch 12a. A constant voltage diode 2 for voltage clamping is provided between the collector of the transistor 17 and the ground terminal.
6 is connected.

On the other hand, the common connection point P of the resistors 24 and 25 in the relay drive circuit 18 configured as described above is pnp
It is connected to the collector of the transistor 27 via a resistor 28. The transistor 27 forms a part of an overcurrent trip circuit 29 as overcurrent protection means, and the overcurrent trip circuit 29 will be described below.

That is, the transistor 27 has its emitter connected to the terminal 3a which is one end of the sampling resistor 16 via the resistor 30, and its base connected to the other end of the sampling resistor 16 via the diode 31 having the polarity shown in the figure. It is connected to a common contact CM of a certain relay switch 12a. The base of the transistor 27 is connected to the ground terminal via the resistor 32.

The resistors 24, 2 in the relay drive circuit 18
5 is also connected to the collector of the pnp transistor 33 via the resistor 34. The transistor 33 forms a part of an undervoltage trip circuit 35 as undervoltage protection means. The undervoltage trip circuit 35 will be described below.

That is, the emitter of the transistor 33 is connected to the terminal 3a via the resistor 36, and is connected to the ground terminal via the constant voltage diode 37 having the illustrated polarity for voltage clamping. The base of the transistor 33 is connected to a resistor 3 connected in series between the terminal 3a and the ground terminal.
8 and 39 are connected to a common connection point.

The resistors 24, 2 in the relay drive circuit 18
5 is connected between the common connection point P and the ground terminal, a capacitor 40 for giving a time constant which is also used in each of the relay drive circuit 18, the overcurrent trip circuit 29, and the undervoltage trip circuit 35. ing.

Next, the operation of the embodiment constructed as described above will be described. When the ACC switch 10 is turned on in a state where the connecting plug 3 is inserted into a cigarette lighter socket (not shown), the terminals 3a and 3a are turned off.
The power is turned on during b. Then, the base current of the transistor 17 is supplied to the resistor 21 and the transistor 17 is turned on.
Is applied to the relay switch 12a and the contact (CM-N
The state is switched from the ON state during C) to the ON state between the contacts (CM-NO).

When the power is turned on, the sampling resistor 16 and the contact of the relay switch 12a (CM-
During NC), a current supply path to the base of the transistor 22 is formed via the resistors 25 and 24. However, the supply of the base current via such a path is delayed by the time constant of the resistor 25 and the capacitor 40. After the power is turned on, the transistor 22 is not turned on, and after the relay switch 12a is turned on between the contacts (CM-NO) in response to the turning on of the transistor 17, the transistor 22 is not turned on. Since the current supply path is cut off, the transistor 22 is not turned on after the elapse of the time constant set in the resistor 25 and the capacitor 40.

The contact (CM-N) of the relay switch 12a
O), when turned on, the terminals 4 of the sockets 4 to 6
a to 6a, and 4b to 6b, the contact points (CM-N
During the period O), the power supply is connected to the vehicle-mounted battery 11 via the sampling resistor 16 and the like, so that the sockets 4 to 6 exhibit a power supply state. Once inserted, power can be supplied to those electrical appliances. In this case, the light emitting diode 7 is energized and turned on to indicate that the sockets 4 to 6 are in a usable state.

When the load current flowing through the sockets 4 to 6 is small, the voltage drop at the sampling resistor 16 is small, so that the voltage between the emitter and base of the transistor 27 in the overcurrent trip circuit 29 is suppressed low. Therefore, the transistor 27 maintains the off state.

On the other hand, if the level of the load current rises beyond the limit, the voltage drop at the sampling resistor 16 increases and the voltage between the emitter and base of the transistor 27 rises to a level sufficient to turn it on. The transistor 27 turns on.

Then, the potential of the common connection point P of the resistors 24 and 25 rises at a speed corresponding to the time constant of the resistors 30 and 28 and the capacitor 40.
The transistor 22 is turned on when a predetermined delay time has elapsed after the turning on of the transistor 7, and the transistor 17 is turned off accordingly. As a result, the relay coil 12b is cut off, and the relay switch 12a returns to a state in which the contacts (CM and NC) are turned on. At the same time, the light emitting diode 7 is turned off and the light emitting diode 8 is energized and turned on, thereby displaying that the sockets 4 to 6 are in an unusable state.

In this case, the transistor 27 is turned off at the moment when the contact (CM-NO) of the relay switch 12a is turned off, but the transistor 22 is turned on by the discharge charge of the capacitor 40 even after the transistor 27 is turned off. After the state is maintained and the relay switch 12a returns to the state where the contact (CM-NC) is turned on, the on state is turned on by the base current supplied through the resistors 25 and 24 between the contacts (CM-NC). As a result, the output stop state in which the transistor 17 is turned off is maintained as it is.

In order to release the output stop state, the ACC switch 10 may be turned off and then turned on again, or the connecting plug 3 may be pulled out from the cigarette lighter socket and then reinserted. .

On the other hand, when the power supply voltage, that is, the voltage between the terminals 3a and 3b is relatively high, the undervoltage release circuit 35
The divided voltage (the transistor 33)
Of the transistor 33 is maintained higher than the clamp voltage (corresponding to the emitter potential of the transistor 33) by the constant voltage diode 37.
Is kept off.

On the other hand, when the power supply voltage falls below the predetermined lower limit voltage due to the decrease in the output of the vehicle-mounted battery 11, the divided voltage by the resistors 38 and 39 becomes lower than the clamp voltage by the constant voltage diode 37. As a result, the transistor 33 is turned on. Then, the potential of the common connection point P of the resistors 24 and 25 rises at a speed corresponding to the time constant of the resistors 36 and 34 and the capacitor 40. As a result, the transistor 22 is turned on, and in response to this, the transistor 17 is turned off and the output is switched to the same state as described above.

In short, according to the configuration of the present embodiment described above, it is possible to obtain a power source for a plurality of vehicular electric appliances through the sockets 4 to 6. In this case, when an excessive load current flows, The current path for the sockets 4 to 6 can be reliably and automatically shut off. Moreover, in this case, it is not necessary to replace the current fuse as in the conventional configuration, so that the maintenance can be simplified. In addition, since the current path to the sockets 4 to 6 is cut off only when the load current exceeds the set value for a predetermined delay time or more, when an excessively large load current temporarily flows. In this case, the operation of interrupting the load current path is not performed, and the usability is improved.

Further, even when the power supply voltage falls below the set lower limit voltage due to a decrease in the output of the vehicle-mounted battery 11, the power supply path to the sockets 4 to 6 is automatically cut off. This eliminates the risk of inadvertently lowering the capacity of the vehicle-mounted battery 11, thereby preventing a situation where the engine cannot be started as in the related art. In addition, since the shut-off operation is performed only when the state in which the power supply voltage falls below the set lower limit voltage continues for a predetermined delay time or more, a temporary interruption of the power supply voltage such as when starting the engine is performed. If there is a descent,
This eliminates the possibility that the above-described energization path cutoff operation is erroneously performed.

[0031]

According to the present invention, as is apparent from the above description, a plurality of sockets branched from a plug connected to a socket for a cigarette lighter are provided, and a power source for a vehicular electric appliance is obtained from these sockets. In such a vehicle auxiliary power supply device, when a state in which the load current flowing through the socket exceeds a set value exceeds a predetermined delay time or more, a cut-off operation of a current path to the socket is performed, and the input voltage is reduced. When the state of falling below the set lower limit voltage continues for a predetermined delay time or more, the operation of shutting off the current path to the socket is performed, so that the protection operation against overcurrent and the maintenance can be simplified, and This has a practical effect that abnormal power consumption can be prevented beforehand.

[Brief description of the drawings]

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

FIG. 2 is an overall perspective view.

[Explanation of symbols]

In the figure, 1 is a main body case, 2 is a power cord, 3 is a connecting plug, 4 to 6 are sockets, 11 is an onboard battery, 12a
Is a relay switch, 12b is a relay coil, 16 is a sampling resistor (current detection means), 18 is a relay drive circuit, 29 is an overcurrent trip circuit (overcurrent protection means), 3
Reference numeral 5 denotes an undervoltage trip circuit (undervoltage protection means).

Claims (1)

(57) [Scope of request for utility model registration] 1. A vehicle comprising: a plug connected to a cigarette lighter socket provided in the vehicle; and a plurality of sockets branched from the plug, from which the power source of the vehicle electrical equipment is obtained. Current detecting means for detecting a load current flowing through the socket in the auxiliary power supply device; and a communication with the socket when the load current detected by the current detecting means exceeds a set value for a predetermined delay time or more. Overcurrent protection means for interrupting the electric circuit, and undervoltage protection means for interrupting the current path to the socket when the state in which the input voltage has dropped below the set lower limit voltage has continued for a predetermined delay time or more. Vehicle auxiliary power supply.