| 摘要 |
PURPOSE:To prevent intrusion of external liquid into a chamber having therein a driving means, by forming an air chamber between the chamber having a driving means and a pump connected directly to the driving means. CONSTITUTION:Providing that the volume of a space in a motor chamber 4 under the atmospheric pressure is V1, the volume of an air chamber 8 under the atmospheric pressure is V2, the maximum discharge pressure of a pump or the maximum pressure developed at the portion where a shaft is extended through when the pump is in operation is P1, and the sum of the volumes of air in the motor chamber 4 and the air chamber 8 is V3, the following relationship, V3= 1/(P1+1)(V1+V2), is satisfied. Here, if the volume V2 of the air chamber 8 is so selected that the level of a liquid 9 entered into the air chamber 8 is lower than the bottom of the motor chamber 4 under the condition of the volume V3, it is enabled to prevent intrusion of external liquid into the motor chamber 4. |
