High Voltage DC Relay Vacuum Brazing

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As a key safety device in new energy vehicles, the high-voltage DC relay needs to have the basic functions of high voltage resistance, load resistance, shock resistance, strong arc extinguishing ability and strong breaking ability. The high-voltage DC relay is a relay used to control high voltage and high current in the DC circuit. It is used for the safe connection between the power battery pack and the vehicle power system. It is an indispensable core key component of new energy vehicles. Fast, small size, high arc extinguishing safety, high reliability of action, long life and so on. The high-voltage DC relay is mainly composed of a high-voltage cavity, an armature mechanism, and an electromagnetic drive.

At present, most of the high-voltage DC relays use copper-based contacts. Copper-based contacts are prone to oxidation reaction in the air, resulting in product performance degradation. It is necessary to use a sealed cavity to prevent electric shock oxidation. Some relays use silver alloy contacts, which can make up for the shortcomings of easy oxidation. At the same time, silver alloys also It has the characteristics of resistance to adhesion and arc burning.

The process of refilling the gas in the relay: first, the air in the vacuum chamber is drawn out through the sealing tube, and then the leakage of the vacuum chamber is detected by a helium mass spectrometer. The qualified products are refilled with gas, and finally the sealing tube is clamped by a mechanical device, and the sealing tube is cut off. Alcohol check the pinch off for leaks. If necessary, a small amount of helium can be added to the mixed gas, and the finished product can be tested for leaks after the mixed gas is refilled to ensure the reliability of the product.

The backfill gas can be one or more mixed gases, and the inflation pressure can be determined in advance according to the design needs. Generally, it is calculated according to the volume of the vacuum chamber of the relay, the service life, and the air pressure at the end of the service life, and the backfill pressure and the air pressure of the relay are obtained. The maximum allowable leakage rate, which can be used as a relay leak detection standard.

Most of the return gas in the vacuum chamber is positive pressure. The commonly used pressure specification is 1.5 atmospheres. This has two advantages. First, the gas has the advantage of pressurized arc extinguishing. The use of positive pressure can improve the arc extinguishing ability of the gas. On the one hand, it can ensure that the vacuum chamber of the relay is always in a positive pressure state during the design life cycle, preventing external air from entering the vacuum chamber, so as to improve the service life of the relay.

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