Electric vacuum pump

Abstract

In an electric vacuum pump, a pump housing and a lower-end cover member respectively include positioning retainers respectively formed on outer peripheries of the pump housing and the lower-end cover member. A case includes positioning retainers each protruding inward from an inner peripheral surface of the case. The positioning retainers are in contact with the positioning protrusions, thereby positioning the pump housing and the lower-end cover member with respect to the case. The positioning protrusions are formed with screw holes.

1 . An electric vacuum pump including: a case having internal space; a motor part placed in the internal space of the case; and a pump part placed in the internal space of the case and to be driven in sync with the motor part, wherein
 the pump part includes: a cylindrical pump housing; a first cover member placed in the pump housing on one end side in a center axis direction of the pump housing; a second cover member placed in the pump housing on the other end in the center axis direction; a pump chamber formed by an inner peripheral surface of the pump housing, the first cover member, and the second cover member; and a rotor housed in the pump chamber and including a plurality of vanes inserted therein,   the electric vacuum pump further includes a fastening member passed through a through hole formed in the first cover member and being fastened in a fastening hole formed in the case to fix the first cover member to the case and the pump housing,   the pump housing is provided with a positioning retainer formed on an outer periphery and the second cover member is provided with a positioning retainer formed on an outer periphery,   the case is provided with a positioning protrusion formed to protrude inward from an inner peripheral surface of the case,   the positioning retainers are in contact with the positioning protrusion to position the pump housing and the second cover member with respect to the case, and   the fastening hole is formed in the positioning protrusion.   
     
     
         2 . The electric vacuum pump according to  claim 1 , wherein the positioning retainers are formed to respectively protrude from an outer peripheral surface of the pump housing and an outer peripheral surface of the second cover member toward the inner peripheral surface of the case and include grooves engageable with the positioning protrusion. 
     
     
         3 . The electric vacuum pump according to  claim 1 , wherein the case has an end face on the one end side in the center axis direction of the pump housing, the end face being located in the same position as an end face of the first cover member on the other end side in the center axis direction of the pump housing or located in a position closer to the one end side than the end face of the first cover member on the other end side. 
     
     
         4 . The electric vacuum pump according to  claim 1 , wherein the pump part and the inner peripheral surface of the case form therebetween a space in an area excepting the positioning protrusion and the positioning retainers. 
     
     
         5 . The electric vacuum pump according to  claim 4 , further including a member placed in the space to produce at least one of a silencing effect and a cooling effect. 
     
     
         6 . The electric vacuum pump according to  claim 4 , wherein the case includes a rib placed in the space and formed to protrude inward from the inner peripheral surface of the case. 
     
     
         7 . The electric vacuum pump according to  claim 1 , wherein
 the case, is provided with a plurality of the positioning protrusions and a plurality of the fastening holes in two or more and odd-numbered pairs, and   one pair of the pairs of positioning protrusions and fastening holes is placed in a position 180° opposite to a center axis of the inner peripheral surface of the pump housing with respect to a rotation center axis of the rotor.   
     
     
         8 . The electric vacuum pump according to  claim 1 , wherein
 the first cover member includes a suction inlet for sucking gas from outside into the pump chamber and a discharge outlet for discharging gas from the pump chamber to the outside, and   the pump housing and the first cover member are integrally formed.   
     
     
         9 . The electric vacuum pump according to  claim 1 , further including
 a cover closing the internal space of the case from a side of the pump part, and   the cover and the first cover member form therebetween a space.   
     
     
         10 . The electric vacuum pump according to  claim 1 , wherein
 the pump housing has a cylindrical shape of which the outer peripheral surface has a polygonal cross section,   the second cover member has a plate-like shape of which the outer peripheral surface has a polygonal cross section, and   each of the positioning retainers is a surface defined by a side of the polygonal cross section.   
     
     
         11 . The electric vacuum pump according to  claim 1 , wherein the case is made of a metal material.