Starting the compressor great strain on the engine. It has to overcome the inertia of the moving parts. (Objects at rest tend to stay at rest.) It should also overcome the high pressure in the crankcase. (In fact, crankcase pressure can be maximum at startup.) It is important to use more powerful. Even so, the engines are usually taxed to the limit at the time of launch. This is particularly true when, starting from the normal or above normal head pressure.
Compressor low pressure control is used in some systems. This will help the low side of the crankcase pressure at a reasonable level, even though the rest of low pressure may be high. He never permits the crankcase pressure exceeds a certain safe values, and is known as a reverse froze, two-temperature valve.
Crankcase pressure-regulating valves are needed where the compressor is running too long before the side of low pressure drops, that does not overload the compressor. Suction line pressure may exceed the safe pressure. In this case, the valve closes off from the compressor suction line.
Valve body, usually made of brass and a diaphragm or bellows of phosphor bronze.
Needle and place, as a rule, made of wear-resistant steel, alloys. Fig. 13-134 shows valve in a typical installation, located in the suction line between the evaporator and the compressor. For some applications, other components of the system should be located after the valve.
Pressure-regulating valve prevents overload of the EC compressor motor. This eliminates the pressure in the crankcase, during and after defrost cycle or after the normal shutdown period. The crankcase pressure-regulating valves are closed as the output pressure increases. They also react to the compressor, sump or suction pressure. They cover the increase in the pressure at the output. Fig. 13-135 shows this valve. Input pressure from the bottom of the bellows and the top side of the seat of the disk.
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