Interconnecting Circuit for Connecting One d.c. Voltage Source to Another

The present invention uses polarity detecting relay means to limit direction of current flow in the wiring of batteries between two vehicles. The relay arrangement allows electric current to flow and charging to begin, when the wiring is correct. In reverse, the relay arrangement cuts out automatically, if the wiring is wrong.

The conventional jumper cable between two vehicles uses usually a long cable having a double line wire. A respective line clamp is installed respectively at the two ends of each line wire for clamping to respective terminals of the batteries in the two vehicles.

Due to negligence of the driver or poor visibility on a dark night, short circuiting may result on the wires. Furthermore, such fault occurs often, when the battery is charged from a charger. The circuit of the present invention uses the polarity detecting relay arrangement to make the electric circuit cut off when it is incorrectly connected. It also may function to provide an indication of an incorrect connection and can improve the above-indicated defects.

FIG. 1A is a schematic diagram of an exemplary embodiment of an interconnecting ("jumper") circuit having polarity detecting relay arrangement in accordance with the present invention.

FIG. 1B is a schematic diagram of a variant of circuit of FIG. 1A, the polarity detecting relay arrangement being connected with voltage-limiting Zener diodes in series.

FIG. 2 is a schematic diagram of a variant of the circuit of FIG. 1A with a wrong polarity indicating LED arrangement.

FIG. 3 is a schematic diagram of a variant of the circuit of FIG. 1A with a delay electric circuit arrangement.

FIG. 4 is a schematic diagram of a circuit of a polarity detecting relay arrangement having a conventional Zener diode providing constant voltage across its winding.

FIG. 5 is a schematic diagram of a circuit of a polarity detecting relay arrangement having a transistor in series with its winding and providing constant current therethrough.

FIG. 6 is a schematic diagram of an interconnecting circuit providing automatic polarity exchange, the circuit being controlled by an exclusive OR gate.

This invention concerns an improved design of an interconnecting ("jumper") circuit between two batteries in different vehicles or from a charger. As known by the people, direct charging between two batteries is usually done in the outdoors or in the absence of a power supply or charger. It is a temporary method for charging the battery having an insufficient electric charge. The correct method for effecting this operation is as follows:

1. the positive pole of one battery connects with the positive pole of the other and the negative pole of the one battery connects with the negative pole of the other; and

2. the battery to be charged should not make a short circuit, otherwise the connecting wires will overheat the battery may be destroyed.

Whenever an operator has insufficient knowledge, or is negligent, or it is too dark, wrong connected polarities may happen. Therefore, applicant has provided the polarity detecting relay arrangement of the present invention to protect it. Its applicable example is shown in FIG. 1A. Its main principle lies in that the wire clamps are installed respectively at the two ends of positive conducting wire of the interconnecting ("jumper") circuit, in which respective polarity detecting relay sets composed of respective relay windings RY101 and RY102 are installed on a section. One end of the respective polarity detecting relay windings RY101 and RY102 connects in positive direction in series with respective diodes CR101 and CR102 which have their anodes connected to the positive conducting wires. When two ends have corrective polarities, current flows in the winding RY101 which causes the pair of contacts RY101C to close; current also flows in the winding RY102 causing the pair of contacts RY102C to close. The two ends of negative conducting wire, also provided with the clamps, connect to the free terminals of the windings RY101 and RY102 which are conductively connected to one another. When the polarities of two ends are correct, the closed pairs of contacts RY101C and RY102C allow electric current to flow for charging between the two batteries. When a battery has too little remaining charge to drive its relay, the charging electric current is cut off. Because battery-to-battery charging is used only for an insufficient electric charge condition of a battery, the two batteries may both become over-heated due to too large charging current, when a battery has become discharged completely. Therefore, this state should be avoided. In order to detect the state of this insufficient terminal voltage condition, the minimum activating terminal voltage can be selected respective Zener diodes ZD101, ZD102 connected respectively between the respective diodes CR101, CR102 and the relay windings RY101, RY102 (as shown in FIG. 1B). If any pole has an incorrect connection polarity, the polarity detecting relay set will not act, due to reverse obstruction of the diode CR101 or CR102, so that at least one of the pairs of contacts RY101C, RY102C remains open and the protective function is achieved. Furthermore, the pairs of contacts of above-said polarity detecting relay arrangement can be alternatively installed in series in the negative conducting wire.

A further variant is shown in FIG. 2, in which the respective diodes CR201, CR202 having reverse polarity in parallel and with respective LED201, LED202 having respective limiting resistors R201, R202 in series therewith to display the reverse polarity connection when present, the respective LED201 or the LED202 emitting light when one or the other of the diodes CR201, CR202 is nonconducting.

Moreover, the elements such as polarity detecting relay set, LED and over current breaker as shown in FIGS. 1A, 1B and 2 can be installed in a housing or installed respectively near by the ends of the charging wire. This structure results in a new effect, i.e. when the charging current is too large, a very large voltage drop results along the charging wire and the relay on the load side switches out and then switches on again, so that a switching cycle is formed. This switching cycle can delay the steady state cycle using a delay electric circuit, functioning somewhat like an automatic return type over-current circuit breaker, and charge the battery initially intermittently.

FIG. 3 is an applicable example of a variant, in which additionally a delay electric circuit is provided. Respective capacitors C301 and C302 have been connected respectively in parallel across the respective detecting relay set windings RY301, RY302 and respectively in series with resistors R301, R302 and the respective diodes CR301, CR302. When the electric charging current flows through the pairs of contacts RY301C, RY302C between the batteries, resistor R301 with capacitor C301 and resistor R302 with capacitor C302 act to provide delay in the appearance of the full voltage across relay windings RY301, RY302, respectively. When either battery has insufficient voltage, the associated one of the capacitors discharges and an off-delay is generated, so that its off and on cycle can be postponed and the voltage of charged battery can rise slowly.

Furthermore, in order to let above-mentioned polarity detecting relay sets act in the different voltage ranges, one can use a conventional control transistor Q501 (FIG. 5) with a constant electric current characteristic to let the relay winding provide current-constant drive in the larger voltage range; or one can use a Zener diode ZD401 (FIG. 4) and an active resistor R401 (FIG. 4) to connect with the relay having a lower active voltage in series for effecting voltage-constant drive in the larger voltage range, so that its active function can be assured.

Moreover, one can select the various components and functions described above to form various designs and to enlarge its applications.

A further design of interconnecting circuit is shown in FIG. 6, in which an exclusive OR gate is used to detect and to control the interconnecting polarity by exchanging automatically the polarities, in case one of the batteries is connected in reverse polarity.

As illustrated in FIG. 6, a preferred embodiment of the interconnecting circuit of the present invention includes a polarity exchange switching circuit having two sets pairs of contacts RY601C1, RY601C2 and RY601C3, RY601C4 of the relay RY601, in which its two connecting contacts of a pair connect to an input of the charging wire and one of double normally closed contacts or double normally opened contacts connects to another input. Its second set of pairs of contacts connect intersectionally, so that two input ends have inverse-parallel connection and parallel-parallel connection, when the polarity exchange relay winding RY601 is energized or is not energized. After its winding RY601 has been connected with a control transistor Q601, it connects with the constant directional power supply in parallel. This relay can be constituted of many types, for example, it may be of the electro-mechanical type relay or the solid-state type.

The circuit of FIG. 6 includes a double set bridge rectifier used for providing respective constant d.c. power supplies. It has double set bridge rectifying circuit composed of diodes CR601, CR602, CR603, CR604 as well as diodes CR605, CR606, CR607 and CR608. Its a.c. inputs connect with two inputs in parallel and its d.c. outputs connect to one another. Therefore, when one of two sets has electricity, then it can supply electric current for the polarity exchange relay inspite of the polarity state of either of the batteries connected with the two inputs.

Polarity detection is provided by dropping resistors R601 and R602, obstructive diodes CR609 and CR610 and two sets of photo-couplers PC601 and PC602 connected respectively with the input ends on two sides in parallel in the positive direction. When the connected polarity of one or the other of the batteries is same as that of its associated obstructive diode, the output of its photo-coupler is switched on. When the connected polarity of the battery is reverse to that of the obstructive diode, the input of the photo-coupler is switched off.

The exclusive OR gate circuit is composed of an IC or an electric circuit component having this logic function and has an output connected with base of the control transistor Q601 and has also two inputs connected with resistors R603 and R604. The resistors R603 and R604 are connected with the output of above-mentioned polarity detecting components for providing the electric signs corresponding to the connected battery polarity.

In operation, when the two inputs connect each other with the same correct polarities respectively, the two input detecting circuits PC601 and PC602 show high or low at the same time and the input of exclusive OR gate shows low. At this moment, the polarity exchange relay winding 601 is not energized.

When two inputs have different polarities, the detecting circuits PC601 and PC602 show a high and a low and the output of exclusive OR gate shows high. The polarity exchange relay winding RY601 is energized and the reverse parallel connection of the battery at two inputs is changed to positive parallel connection, so that the possible damage to the battery or other accidents can be avoided.

The charging protective equipment described in FIGS. 1A, 1B and 2-6 can be further used in conjunction with a charger, i.e. the battery is replaced by the output of d.c. power supply of the charger. The above-said electric circuit can be installed in the housing or on the transmission conducting wire.

Based on the above description, this design uses the polarity detecting relay set to avoid the shortcomings of the conventional charging interconnecting ("jumper") circuit. It has the functions of a fault alarm and provides protection or automatic polarity correction.