Roots vacuum pump

Abstract

The present invention relates to a roots vacuum pump which is capable of implementing a good outer appearance and an improved layout design of a pump by forming a certain path through which a remaining compression gas is returned to a suction port side of a roots pump in a housing of a roots pump in the case that a gas compressed by a roots pump is not fully exhausted by a latter part pump and remains in an exhaust pot side of the roots pump and is capable of concurrently operating a roots pump and a latter part pump. The roots vacuum pump apparatus in which a root pump and a latter part pump are connected, includes bypass paths formed in at least one inner surface among the inner surfaces of the front cover and the rear cover for communicating the suction pot and exhaust port of the cylinder, and an one-way valve installed in an inlet of the bypass path contacting with the exhaust port for opening the bypass path when a pressure of the exhaust port exceeds a certain level.

What is claimed is:  
     
         1 . In a roots vacuum pump apparatus in which a suction port and an exhaust port are formed at both sides of a roots pump cylinder having a pair of rotors which are supported by a rotary shaft and are rotated in an engaged state, a front cover and motor fixing plate are sequentially engaged in one side of the cylinder, and a rear cover and a gear box are sequentially engaged in the other side of the same, and an exhaust port is connected with the latter part pump, a roots vacuum pump apparatus, comprising: 
 bypass paths formed in at least one inner surface among the inner surfaces of the front cover and the rear cover for communicating the suction pot and exhaust port of the cylinder; and    an one-way valve installed in an inlet of the bypass path contacting with the exhaust port for opening the bypass path when a pressure of the exhaust port exceeds a certain level.    
     
     
         2 . The apparatus of  claim 1 , wherein said one-way valve includes a valve guide installed in a wall surface of the cover opposite to the inlet of the bypass path, a valve member movable based on a guide of a valve guide for opening and closing the inlet of the bypass path an opposite direction with respect to the valve guide, an elastic member disposed between the valve member and the valve guide for generating a certain elastic force in order for the valve member to closely contact with the inlet of the bypass path, and an  0 -ring formed in a contact surface of the valve member.  
     
     
         3 . The apparatus of  claim 1 , wherein a motor housing is engaged to one side of the motor fixing plate, and a can housing is engaged in such a manner that the interior of the motor housing is sealed, and a stator is installed in the interior of the can housing, and a motor rotor is fixed in an outer surface of the rotary shaft in such a manner that the motor rotor is protruded to the outside of the motor fixing plate for thereby implementing a good sealing state and an easier attaching and detaching operation of the motor.