| 摘要 |
A vacuum pump driven by an electric motor 12 comprises a reciprocating piston 194 sealed to a housing 162 by a rolling lobe diaphragm 202, buckling of the diaphragm during reciprocation being prevented by a mechanical basing arrangement 208, 212 which acts on the lobe portion of the diaphragm. The biasing arrangement is formed by balls 208 retained in contact with the diaphragm by disc 212 which has radial slits to form flexible fingers (216). The motor 12 includes a pair of relatively movable sequentially operating armatures 34, 74 which eliminate the need for any external timing mechanism or for any complex delay mechanism. A spring 228 performs the upward stroke of the piston 194 and the armature 74 the downward stroke when a coil 132 is energised through contacts 38, 91. The motor is inherently capable of operating the pump as a self-actuating demand pump. <IMAGE> |
