1. Field of the Invention
The present invention relates generally to a motor, and more particularly, to a rear cover mounted to the motor.
2. Description of the Related Art
A conventional motor includes a case, a rotor received in the case, and a rear cover connected to the case to seal the rotor. For assembling such motor, the rotor is put into the case first, and then engaged with an annular plug with a bore of the case to mount the rear cover on the case by screws that a spindle of the rotor passes through the rear cover via a center bore thereof.
Typically, the rear cover is made of plastic with high rigidity and is high heat-resistant. It is made by injection molding such that the annular plug and the center bore are formed in the molding process. Due to thermal expansion of plastic and the difficulty in managing precision of the cavity of the molding, the annular plug 1 is deformed, which means an outline of the plug 1 is not round. When user, as shown in
The primary objective of the present invention is to provide a motor rear cover, which has a firm structure of connection with the motor case.
According to the objective of the present invention, a motor rear cover, which is connected to a motor case having a connecting bore, includes a main body and a plurality of protrusions. The main body has an annular plug, on which the protrusions are provided. The annular plug is inserted into the connecting bore and the protrusions will press a sidewall of the connecting bore.
In addition, diameter of the annular plug is slightly smaller than that of the connecting bore.
As shown in
The annular rim 121 has a top face 121a and two bores 121b. Two bolts 40 may be inserted into the bores 121b and screwed into the threaded bores 24 of the motor case 20 to secure the main body 12 to the motor case 20.
The carbon brush bases 122 are symmetric and each has a recess 122a to receive a carbon brush 50 therein.
The annular plug 123 is axially projected from the top face 121a of the annular rim 121. As shown in
The ribs 124 connect the annular rim 121 and the spindle base 125 to provide a stronger structure.
The spindle base 125 has a round bore 126, which has a big-diameter section 126a and a small-diameter section 126b to receive a first bearing 60 and a second bearing 70 therein that the spindle 30 passes through the first bearing 60 and the second bearing 70.
The positioning block 127 is on the top face 121a of the annular rim 121.
The protrusions 14 are on the circumference 123a of the annular plug 123 with a constant interval therebetween. Each of the protrusions 14 has a block 142 and a tapered portion 141 at a front end of the block 142. As shown in
Before assembling the motor rear cover 10 and the motor case 20, the rotor 30 is put in the motor case 20. Next, align the positioning block 127 of the motor rear cover 10 with the positioning bore 26 of the motor case 20, and then align the annular plug 123 with the connecting bore 22. In engagement of the annular plug 123 and the connecting bore 26, the tapered portions 141 of the protrusions 14 guide the annular plug 123 to a desired position. Following, exert the motor rear cover 10 to force the annular plug 123 entering the connecting bore 22 that the annular plug 123 is fit to the connecting bore 22 in interference fitness because of the protrusions 14. Even if the connecting bore 22 or the protrusion 142 is deformed or deviated, it will not affect the interference fitness of the annular plug 123 and the connecting bore 22, as shown in
The description above is a few preferred embodiments of the present invention. Those equivalences of the present invention are still in the scope of claim construction of the present invention.