Abstract:
An automatic detecting and switching vehicle charger having a power control circuit is disclosed. A power supply control circuit is connected to a positive electrode clip and a negative electrode clip for supplying power to a battery of a car; a conductive end of the positive electrode clip being further connected to an input end of the power supply control circuit through a signal conductive wire. The power supply control circuit is formed by a power supply unit, a parallel connected relay unit, a serial connected relay unit, a fault detection unit, a low level positive voltage detection unit, a high level positive voltage detecting unit, a reference voltage unit, an alarm unit and a state display unit. In that, the power sources are switched automatically and thus the user is unnecessary to prepare a plurality of batteries as standby devices.

Description:
FIELD OF THE INVENTION 
     The present invention relates to vehicle chargers, and particularly to an automatic detecting and switching vehicle charger. 
     BACKGROUND OF THE INVENTION 
     Referring to FIG. 1, a prior art emergency device  1  of a charger of a vehicle is illustrated. In this prior art, battery  11  is connected to a positive electrode clip A and a negative electrode clip B (referring to FIG.  1 — 1 ). The connecting ends A 1  and B 1  of the clips A and B, respectively, clamp the positive electrode C 1  and negative electrode C 2  of a car so that when the power of the vehicle is insufficient. The power can be conducted from the battery  11 . 
     However, in general, when the emergency device  1  is actuated, since the two ends of the clips A and B are opened. If the two ends A 1  and B 1  are contacted to one another, a large short circuit will be induced so as to generate a spark. This will induce a great threat to the children. Moreover, it is possible that the two electrodes are connected reversely so as to destroy the devices in the vehicle, such as computers, audios, etc. 
     To improve this defect, in one design, a positive electrode voltage detecting circuit and a negative electrode voltage detecting circuit are used to detect the polarities of the charger C. Thereby, before conduction, the clips A and B are insulated, when the positive electrode voltage detecting circuit detects a positive voltage, the small power relay conducts, and meanwhile a large power relay will excite so as to form a loop. 
     However, above mentioned device has some defects. Firstly, when the clips A and B are connected with wrong polarities. Since the large power relay is conductive, the polarities cannot be determined correctly and thus short circuit cannot be effectively avoided. Moreover, since in general, the voltage of a vehicle charger is generally 12V or 24V, but it is often that the voltage of the charger is not clearly indicted, if the large power relay is connected. It is possibly that the battery will be destroyed. Thereby, the prior art charger protection device has still some defects. 
     SUMMARY OF THE INVENTION 
     Thereby, the object of the present invention is to provide an automatic detecting and switching vehicle charger; a power supply control circuit being connected to a positive electrode clip and a negative electrode clip for supplying power to a battery of a car; a conductive end of the positive electrode clip being further connected to an input end of the power supply control circuit through a signal conductive wire; the power supply control circuit comprising: a power supply unit including a first battery and a second battery, and a main switch for controlling the switching of power; a parallel connected relay unit including a small power parallel connected relay set which is formed by two parallel connected small power relays, and a large power parallel connected relay set which is formed by two parallel connected large power relays; a serial connected relay unit being formed by a small power serial connected relay set having a small power relay and a large power serial connected relay set having the large power relay; a low level positive voltage detection unit is a detection circuit which includes an operation integrated circuit, a resistor and a first transistor and an input point of the power supply control circuit being connected to a positive voltage through a diode in a positive direction for rising the voltage to a third pin of an integrated circuit; a high level positive voltage detecting unit including a comparator which is formed by an operation integrated circuit, a limiting resistor and a second integrated circuit; the high level positive voltage detecting unit being connected to the input end of the power supply control circuit through a diode along a positive direction; then input voltage being divided by the resistors and then the divided voltages are outputted to a fifth pin of the operation integrated circuit; a reference voltage unit being connected to input ends of the low level positive voltage detecting unit and the high level positive voltage detecting unit for providing reference voltage; a fault detection unit including an operation integrated circuit; an input end of the fault detection unit being connected to a lower level voltage of the reference voltage unit and an input end for detecting the fault of the input end; an alert unit being connected to an output end of the fault detection unit for alerting faults; a state display unit being formed by resistors and displays for displaying various conditions; the states are switched by a third transistor, a fourth transistor and diodes and resistor. 
     By above structure, when the main switch is actuated, if it is not conducted, the large power relays will not conduct so that the power supply unit and output end has no voltage; thereby, the object of short circuit proof is achieved; if the polarities of the power supply control circuit is connected, the input end will has a positive voltage; when the positive voltage is larger than the reference voltage of the reference voltage unit, the exciting coil of the small power relay will is excited and the exciting coil of the large power relay is induced so that a lower level loop is formed; if the positive voltage captured from the input end is divided and the divided voltage is larger than a reference voltage of the reference voltage unit, the third transistor will ground and conduct, then the small power relay will conduct so that the large power relay is excited; then, the two batteries are serially connected so as to form a high level conductive loop so as to trigger the fourth transistor to conduct so that the low level positive voltage detection unit is shorted to the negative electrode so as to cut off the circuit; if another clip is pulled out, if no voltage is derived from the input end, then the small power relay will stop exciting so that the power supply unit will turn off. 
    
    
     The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a prior art charger. 
     FIG.  1 — 1  shows that a prior art emergency charger is clamped to a charger of a car. 
     FIG. 2 is a structural block diagram of the present invention. 
     FIG. 3 is a circuit diagram of the present invention. 
     FIG. 4 shows that the present invention is clamped to a battery of a car. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The automatic detecting and switching vehicle charger of the present invention will be described herein after. In the present invention, a power supply control circuit  2  is connected to a positive electrode clip A and a negative electrode clip B (referring to FIG. 3) for supplying power to the battery C. A conductive end A 1  of the positive electrode clip A is further connected to an input end I/P of the power supply control circuit  2  through a signal conductive wire D. The method and structure of the present invention will be described herein. 
     The power supply control circuit  2  (referring to FIG. 2) is formed by a power supply unit  21 , a parallel connected relay unit  22 , a serial connected relay unit  23 , a fault detection unit  24 , a low level positive voltage detection unit  25 , a high level positive voltage detecting unit  26 , a reference voltage unit  27 , an alarm unit  28  and a state display unit  29 , as shown in the FIG.  3 . 
     The power supply unit  21  includes a first battery  211  and a second battery  212 , and a main switch  213  for controlling the switching of the power source Vcc. 
     The parallel connected relay unit  22  includes a small power parallel connected relay set  221  which is formed by two parallel connected small power relays RELAY 2 -RELAY 3 , and a large power parallel connected relay set  222  which is formed by two parallel connected large power relays RELAY 5  and RELAY 6 . The normal-open joints of the small power relays RELAY 2  and RELAY  3  are connected to the exciting coils  5   d  and  6   d , respectively, of the large power relays, RELAY 5  and RELAY 6  and then further connected to the ground end. After the exciting coil  5   d  of the RELAY 5  is serially connected to the second battery  212 , the negative electrode is connected to the ground end. Thereby, in conduction, the first battery  211  and second battery  212  of the power supply unit  21  are connected together so as to generate a lower level power output. 
     The serial connected relay unit  23  is formed by a small power serial connected relay set  231  having the small power relay RELAY 1  and a large power serial connected relay set  232  having the large power relay RELAY 4 . The normal opening joint  1   a  of the small power relay RELAY 1  is connected to the exciting coil  4   d  of the large power relay RELAY 4  and then is further grounded. Thereby, in conduction, the first battery  211  and second battery  212  of the power supply unit  21  are directly and serially connected to a high level power output end; and the exciting coil  1   d  of the small power relay RELAY 1  is connected to common joints  2   c  and  3   c  of the small power relays RELAY 2  and RELAY 3 , respectively, of the small power parallel connected relay set  221 . The exciting coil  4   d  of the large power relay RELAY 4  is serially connected to the normal opening joint  4   a  and then is connected to common joint  5   c  of the large power relay  5  of the large power parallel connected relay set  222  so that the serial connected relay unit  23  can be switched with the parallel connected relay unit  24 . 
     The low level positive voltage detection unit  25  is a detection circuit which includes an operation integrated circuit U 1 A, a resistor  16  and a first transistor  252  and an input point I/P of the power supply control circuit  2  is connected to a positive voltage through a diode in a positive direction for rising the voltage to a third pin (+) of an integrated circuit U 1 A. 
     The high level positive voltage detecting unit  26  includes a comparator which is formed by an operation integrated circuit U 1 B, a limiting resistor R 11  and a second integrated circuit  261 . The high level positive voltage detecting unit  26  is connected to the input end I/P of the power supply control circuit  2  through a diode D 2  along a positive direction. Then input voltage is divided by the resistors R 12 , R 13  and then the divided voltages are outputted to a fifth pin (+) of the operation integrated circuit U 1 B. 
     The fault detection unit  24  includes a short signal comparator and a negative voltage signal comparator. The short signal comparator includes an operation integrated circuit UIC, and resistors R 18 , R 19 , and R 20  and the negative voltage signal comparator includes an operation integrated circuit UID, and resistors R 2 , R 21 , R 22 , R 23  and R 24 . When the input end I/P is shorted, the ninth pin (−) of the operation integrated circuit UIC will capture a short current. The current is compared with the ground of tenth pin (+) from the resistor R 20 . Then the grounded eighth pin (output) outputs a high voltage so that the integrated circuit UID will capture a negative voltage by the diode D 1  reversely connected. Thereby, the fourteen pin (output) will output a high voltage. 
     The reference voltage unit  27  is formed by resistors R 5 , R 6  and R 7  and a Zener diode ZD 2 . The resistors R 7  serves for limiting current. The Zener diode, a driving diode Q 1 , a buzzer BZ and resistors R 4 , R 8 , R 9  and R 10 . The Zener diode serves for regulating voltages with a voltage of about 2.5 V. Then the voltage is divided by the resistors R 5  and R 6  and then the divided voltages are outputted to a reference voltage lower than one volt to the second pin (−) of the operation integrated circuit U 1 . 
     The alert unit  28  is formed by a music IC ICU 2 , a Zener diode ZD 1 , a driving transistor Q 1 , a buzzer BZ and a resistors R 4 , R 8 , R 9  and R 10 . The Zener diode ZD 1  serves for regulating voltage. The resistor,R 4  serves to limiting current. By the resistor R 4 , the high voltages of the 8 th  and 14 th  pins of the operation integrated circuit UIC and operation integrated circuit UID in the fault detection unit  24  are received so that the music IC ICU 2  will generate a push-pull current through the resistor  29  so that the buzzer BZ will actuate. Thus the object of alerting will be achieved. 
     A state display unit  29  is formed by resistors R 14 , R 15 , and R 17  and displays LED 1 , LED 2 , and LED 3  for displaying various conditions. 
     The states are switched by a third transistor  291 , a fourth transistor  292  and diodes D 4 , D 5  and resistor R 1 . 
     By above structure, when the main switch  213  is actuated, if it is not conducted, the large power relays will not conduct so that the power supply unit and output end has no voltage. Thereby, the object of short circuit proof is achieved. If the electrodes of the power supply control circuit are connected, the input end will has a positive voltage. When the positive voltage is larger than the reference voltage of the reference voltage unit  27 , the exciting coil of the small power relay will is excited and the exciting coil of the large power relay is induced so that a lower level loop is formed. If the positive voltage captured from the input end is divided and the divided voltage is larger than a reference voltage of the reference voltage unit  27 , the third transistor  291  will ground and conduct, then the small power relay will conduct so that the large power relay is excited. Then, the two batteries are serially connected so as to form a high level conductive loop to trigger the fourth transistor  292  to conduct so that the low level positive voltage detection unit is shorted to the negative electrode so as to cut off the circuit; if another clip is pulled out, and if no voltage is derived from the input end, then the small power relay will stop exciting so that the power supply unit will turn off. 
     Referring to FIGS. 2 and 3, in the present invention, exciting coils of the small power relays  221 ,  231  of the parallel connected relay unit  22  and the serial connected relay unit  23  are serially connected to the low level manual switch  3  and a high level manual switch  4 . The low level manual switch  3  will enforce the parallel connected relay unit  22  to conduct when the voltage is lower than a set value of determining a low voltage. If the level voltage (for example, 24V) battery C is lower than a set value (for example, 14V) of determining a high voltage so that the system seems that it is a low voltage output, then a high level manual switch  4  can be actuated to enforce the serial connected relay unit  23  to conduct so as to have a high voltage output. Thereby, the system can be actuated. 
     The state display unit  29  and the alert unit  28  may be an image device selected from one of light emitting diodes, liquid crystal displays, and bulbs or a speech device. The controlling elements of the low level positive voltage detection unit  25  and high level positive voltage detection unit  26  may be one of diodes, transistors, rectifiers, comparators, and operational amplifiers, etc. 
     Although the present invention has been described with reference to the preferred embodiments, it will be understood that the invention is not limited to the details described thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.