JPS63202218A - Overcurrent protector for capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an overcurrent prevention device for a capacitor provided in parallel with a vehicle battery in order to stabilize the output voltage of the battery.

[Prior Art] In order to prevent fluctuations in battery voltage due to the occurrence of load dump surges, starter startup, or superposition of high-frequency ripple voltage, it is conceivable to provide a capacitor with a relatively large capacity on the battery power line.

[Problems to be Solved by the Invention] By the way, when the battery is removed and reconnected for inspection inside the engine compartment or battery replacement, a large current flows into the discharged capacitor, causing ignition or heat generation. However, there is a problem in that it becomes extremely difficult to handle.

The present invention aims to solve this problem, and aims to provide a capacitor overcurrent prevention device that prevents a large current from flowing into a capacitor when a battery is connected, thereby making it easier to handle when a battery is connected. Be selfish.

[Means for Solving Problems] To explain the configuration of the present invention with reference to FIG. 1, the overcurrent prevention device includes a switching contact 3 provided in a line connecting a battery 1 and a capacitor 2, and A current limiting resistor 4 provided in parallel,
A driving means 5 for operating the opening/closing contact 3; and a control means 6 for detecting the charging voltage of the capacitor 2 and causing the driving means 5 to close the opening/closing contact 3 when the charging voltage is equal to or higher than a predetermined value. Equipped with

[Function] In the device of the present invention, when the battery is removed for replacement or the like, the capacitor is discharged and its charging voltage gradually decreases. When the charging voltage falls below a predetermined value, the control means opens and closes the opening/closing contact via the driving means.

When the battery is reconnected, the charging current to the capacitor is limited to a sufficiently small value by flowing through the current limiting resistor. The capacitor is charged and the charging voltage increases, and when this reaches the predetermined value or more, the switching contact is operated to close, and the battery and the capacitor are directly connected.

[Effects] According to the present invention, a large charging current to a capacitor when a battery is connected is restricted, and thus handling at the time of connection becomes extremely easy.

[Embodiment] In FIG. 1, an alternator 7 is connected to an on-vehicle battery 1, and a starter 8 is further connected to it via an opening/closing contact 3. A capacitor 2 is provided between the switching contact 3 and the starter 8, and its positive electrode is connected. A current-limiting resistor 4 is provided in parallel with the opening/closing contact 3, and both ends of the current-limiting resistor 4 are connected to a control circuit 6, which will be described later. The control circuit 6 controls the operation of the drive motor 5, and the drive motor 5 operates the opening/closing contact 3.

The capacitor 2, switching contact 3, current limiting resistor 4, drive motor 5, and control circuit 6 are housed in an integrated case 9 as described later.

The control circuit 6 includes a pair of diodes 61 and 62 connected to the current-limiting resistor 4 and having their cathodes facing each other, a pair of comparators 63 and 64 that input a divided voltage of the line voltage a from the capacitor 2, and the comparator 6
The drive motor 5 is comprised of a driver circuit 65 that rotates the drive motor 5 in the forward and reverse directions according to the output signal of 3.64.

The above comparators 63 and 64 are M manufactured by Fujitsu Ltd.
B3761 was used, and as the driver circuit 65, M54543 manufactured by Mitsubishi Electric Corporation was used. Power for these comparators 63, 64 and driver circuit 65 is supplied from between the cathodes of the diodes 61, 62.

Hysteresis is provided to the comparators 63 and 64, and the output signal 63a of the comparator 63 changes from the "0" level to the "1" level when the pressure Va is 9.4V or more, and "1" when the pressure Va is 9.0V or less. The level changes from "1" level to "0" level. Also, the output signal 64a of the comparator 64
changes from the "1" level to the "0" level when the above voltage is 8.3V or higher, and changes from the "0" level to the "1" level when the voltage is 7.7V or lower.
Change to level. The driver circuit 65 causes the drive motor 5 to rotate forward when the signal 63a is at the "1" level, and rotates the drive motor 5 in the reverse direction when the signal 64a is at the "1" level.

In FIGS. 2 and 3, the case 9 is a rectangular cylinder made of resin, and the opening/closing contact 3, the current limiting resistor 4, and the drive motor 5 are housed in the case 9, which is assembled integrally with a frame 91. It is. The control circuit 6 is formed on a printed board 92 which also serves as a substrate.

The drive motor 5 is provided facing downward, and its output shaft is connected via a gear group 51 to a rotating shaft 52 provided in a vertical position. The rotating shaft 52 is provided with a substantially rectangular cam body 53.

The opening/closing contact 3 consists of a pair of phosphor bronze arms 31A and 31B whose base ends are held on both sides of the stand, respectively, and the arm 3.
It consists of silver contacts 32 which are provided at the ends of the contacts 1A and 31B that are close to each other and are brought into contact with each other for electrical conduction. The current limiting resistor 4 is connected between the base ends of the arms 31A and 31B, and one end of electric wires 33 and 34 leading to the vehicle battery 1 and the starter 8 are connected to these base ends, respectively.

An aluminum foil electrode 21 and an electrolytic paper 22 are provided on the outer periphery of the case 9.
The capacitor 2 is formed by winding the capacitors alternately. The electrodes 21 are connected by caulking at every other edge, and one is the positive electrode and the other is the positive electrode.
The other is the negative electrode. The positive electrode is connected to the electric wire 34 by the lead wire 23, and the negative electrode is grounded. The above electrode 21
The electrolytic paper 22 is entirely covered with a resin layer 24.

In the overcurrent prevention device having the above structure, when the battery is removed, the capacitor is gradually discharged, and when the voltage Va becomes 7.7V or less, the signal 64a goes to the "1" level and the drive motor 5 is reversed via the driver circuit 65. It will be done. As the motor 5 reverses, the cam body 53 rotates from the horizontal position shown in the figure to the vertical position hitting the stopper 54, and pushes the arms 31A, 31B apart at both ends thereof. As a result, the contact 32
are separated.

When the battery 1 is reconnected in this state, a charging current flows through the discharged capacitor 2, but this is limited to a sufficiently small value by the current limiting resistor 4.

Therefore, sparks and heat generation due to large currents do not occur when connecting the battery terminals, and handling is extremely easy.

Capacitor 2 is charged and the voltage Va becomes 9.4V.
At this point, the signal 63a goes to the "1" level, causing the drive motor 5 to rotate forward through the driver circuit 65, and the cam body 53 returns to the horizontal position (the state shown in the figure) in contact with the stopper 54. This causes the contacts 32 to become electrically conductive again. In this case, since the capacitor 2 has already been sufficiently charged, no large charging current will flow.

In the above embodiment, since the capacitor 2, the switching contact 3, the current limiting resistor 4, and the control circuit 6 are provided in the integrated case 9, it can be easily installed in the engine compartment of the vehicle.

In the embodiments described above, semiconductor elements can also be used as switching contacts.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the overcurrent prevention device, FIG. 2 is a horizontal sectional view thereof, and FIG. 3 is a vertical sectional view thereof. 1... Vehicle battery 2... Capacitor 21... Aluminum foil electrode 22... Electrolytic paper 3... Opening/closing contacts 31A, 31B... Arm 32... Contact 4... Current limiting resistor 5 ... Drive motor (drive means) 52 ... Rotating shaft 53 ... Cam body 6 ... Control circuit (control means) 7 ... Alternator 8 ... Starter 9 ... Case

Claims (2)

[Claims] (1) An overcurrent prevention device for a capacitor connected in parallel to an on-vehicle battery, which includes a switching contact provided in a line connecting the battery and the capacitor, a current limiting resistor provided in parallel with the switching contact, and the above-mentioned A capacitor comprising: a drive means for operating the opening/closing contact; and a control means for detecting the charging voltage of the capacitor and causing the drive means to operate the contact to close when the charging voltage is equal to or higher than a predetermined value. overcurrent protection device. (2) A patent claim in which the opening/closing contact, the current limiting resistor, the drive means, and the control means are integrally housed in a case, and the capacitor is constructed by winding a foil electrode sandwiching electrolytic paper around the outer periphery of the case. An overcurrent prevention device for a capacitor according to item 1.