| 摘要 |
A rotary vane-type vacuum pump with a backward flowing preventing device is provided to promptly interrupt flowing backward to vacuum equipment by promptly releasing an oil pressure of an upper oil space through oil paths formed at a piston simultaneously with returning motion of a first spring of a backward flowing preventing device when a pump module stops. A piston(10) has a valve rod(12) combined with a valve plate(11) for opening and shutting an intake port(101) and has an oil path dividing a working space into an upper oil space(71a) and a lower oil space(71b) and communicating the upper oil space with the lower oil space. A first spring(20) is installed under the piston for elastically supporting the piston. A passage A(31) is directly communicated with the upper oil space of the piston from an oil pump installed at a pump module. Another passage B(32) is directly communicated with an oil storage from the lower oil space of the piston.
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