As described earlier, the electrical current to the solenoid of a proportionalvalve needs to be regulated and not just simply switched on or off as is the case with a conventional valve.
作为简单描述，提供给比例阀电磁铁的电流需要被调节，不象应用常规阀的时仅有开关通或断那样简单。
2
A further difference between a switching solenoidvalve and a proportional valve is in the design of the spool.