Patent Publication Number: US-2012037436-A1

Title: Motor unit and vehicle equipped therewith

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0078518 filed in the Korean Intellectual Property Office on Aug. 13, 2010, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a motor unit. More particularly, the present invention relates to a motor unit that uses electrical energy to generate torque for moving a vehicle, and a vehicle having it. 
     (b) Description of the Related Art 
     Recently, automobiles with good fuel economy have been in high demand, and as one example of automobile manufactures&#39; efforts to meet these demands, hybrid cars with extremely low fuel consumption have been developed. 
     Particularly, a hybrid car is provided with an auxiliary power mechanism (a motor assist mechanism), wherein an engine provides the main power and a DC brushless motor assists the engine upon acceleration or the like. 
     The motor assist mechanism is subject to many constraints in installation, since a brushless motor is disposed in a limited space between the engine and a transmission in an engine compartment. Thus, such a brushless motor is required to have a thin configuration. 
     As described above, the compact brushless motor includes a rotor directly connected to a crank shaft of an engine, and a ring-like stator enclosing the rotor. The stator includes magnetic poles that have windings on cores, a stator holder that contains the magnetic poles, and a centralized distribution unit that concentratedly distributes current to the windings. 
     The central distribution unit is used in a 3-phase DC brushless motor to have ring-like bus bars, and each bus bar includes a ring-like body, a terminal portion protruding in a radial direction of the body, and a connecting portion protruding in an opposite direction of the terminal portion. The terminal portion receives a current from a battery, and the connecting portion is electrically connected to an end portion of the wire that is wound on the bus bar. 
     It is necessary to securely connect one end of the wire wound on the bus bar to the connecting portion of the bus bar in a compact space. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to provide a motor unit having advantages of securely connecting a connecting portion of a bus bar with a wire. 
     A motor unit according to an exemplary embodiment of the present invention may include a bus bar receiving a current from a power supply, a wire that is wound along the bus bar, and a connecting portion that is extended from the bus bar to be electrically connected to one end portion of the wire, wherein the connecting portion has a circular bent portion that is formed along the outer circumference of the wire. 
     The connecting portion may include a first extension portion that is formed by bending one side of the bus bar inwardly, and a second extension portion that is integrally formed with the first extended portion but that is extended at a predetermined angle therewith, wherein the circular bent portion may be formed in the connected portion between the first extension portion and the second extension portion, and has a curvature radius such that the outer circumference of the wire coincides with the curvature. 
     A crossing angle between the first extension portion and the second extension portion may be acute, and the outer circumference of the wire may be in a surface contact state with the inside surface of the bent portion between the first extension portion and the second extension portion. 
     The curvature radius and the section radius of the wire may be identical to each other. 
     The inside surface of the bent portion and the outside surface of the wire are welded to each other to be electrically connected. 
     The bus bar may include a U-bus bar, a V-bus bar, and a W-bus bar that supply 3-phase power, wherein the connecting portion may be respectively integrally formed with the U-bus bar, the V-bus bar, and the W-bus bar, and further the U-bus bar, the V-bus bar, and the W-bus bar may be respectively fabricated through different molds. 
     A vehicle according to an exemplary embodiment of the present invention may include a wheel that is disposed at a lower portion of a vehicle body, and the motor unit that is disposed in the vehicle body to transfer torque to the wheel so as to move the vehicle body. 
     In the motor unit according to the present invention as stated above, the connecting portion of the bus bar includes a bent portion, and one end portion of the wire wound on the bus bar contacts the bent portion such that welding becomes easier and the welded portion is firm. 
     Further, the connecting portion includes the first extension portion and the second extension portion that are at an acute angle such that the wire is not separated from the connecting portion and the welding process becomes easier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a central distribution unit that is mounted in a motor unit according to an exemplary embodiment of the present invention. 
         FIG. 2  is an exploded perspective view of a central distribution unit that is mounted in a motor unit according to an exemplary embodiment of the present invention. 
         FIG. 3  is a partial perspective view of a central distribution unit that is mounted in the motor unit according to an exemplary embodiment of the present invention. 
         FIG. 4  is a partial top plan view of a central distribution unit that is mounted in a motor unit according to an exemplary embodiment of the present invention. 
     
    
    
     DESCRIPTION OF SYMBOLS 
     
         
         
           
               100 : central distribution unit 
               110   a : U-terminal 
               110   b : V-terminal 
               110   c : W-terminal 
               200   a : U-bus bar 
               200   b : V-bus bar 
               200   c : W-bus bar 
               200   d : ground bus bar 
               300 : connecting portion 
               300   a : first extension portion 
               300   b : bent portion 
               300   c : second extension portion 
               400 : wire 
               410 : welding portion 
           
         
       
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings, 
       FIG. 1  is a perspective view of a central distribution unit that is mounted in a motor unit according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , a motor unit includes a central distribution unit  100 , and the central distribution unit  100  is included in a stator of a motor unit to centralize current energy on a wound wire. 
     The rotor and the stator included in a motor unit are known to the public, so detailed descriptions thereof are omitted in an exemplary embodiment of the present invention. 
     As shown, the central distribution unit  100  has a ring shape, and a U-terminal  110   a , a V-terminal  110   b , and a W-terminal  110   c  respectively protrude outwardly so as to receive 3-phase power. 
     The U-terminal  110   a , the V-terminal  110   b , and the W-terminal  110   c  are connected to an external battery or a generator (not shown) to receive a 3-phase current. Further, a non-illustrated wire is wound along the central distribution unit  100 , and the central distribution unit  100  supplies the current with the wire. 
       FIG. 2  is an exploded perspective view of the central distribution unit  100  that is mounted in a motor unit according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , the central distribution unit  100  includes a U-bus bar  200   a , a V-bus bar  200   b , a W-bus bar  200   c , and a ground bus bar  200   d  that have a ring shape, and the U-terminal  110   a  is formed on the U-bus bar  200   a , the V-terminal  110   b  is formed on the V-bus bar  200   b , and the W-terminal  110   c  is formed on the W-bus bar  200   c.    
     The U-bus bar  200   a  receives a current through the U-terminal  110   a , the V-bus bar  200   b  receives a current through the V-terminal  110   b , and the W-bus bar  200   c  receives a current through the W-terminal  110   c.    
       FIG. 3  is a partial perspective view of the central distribution unit that is mounted in the motor unit according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 3 , a connecting portion  300  is respectively formed at the U-bus bar  200   a , the V-bus bar  200   b , the W-bus bar  200   c , and the ground bus bar  200   d , and the connecting portion  300  is respectively connected to one end portion of a wire that is wound along the central distribution unit  100 . 
     More particularly, one end of a first wire (not shown) that is wound along the central distribution unit  100  is connected to the connecting portion  300  of the U-bus bar  200   a , and the other end thereof is connected to a connecting portion of the ground bus bar  200   d.    
     Further, one end of a second wire (not shown) that is wound along the central distribution unit  100  is connected to a connecting portion of the V-bus bar  200   b , and the other end thereof is connected to a connecting portion of the ground bus bar  200   d.    
     One end of a third wire (not shown) that is wound along the central distribution unit  100  is connected to a connecting portion of the W-bus bar  200   c , and the other end thereof is connected to a connecting portion of the ground bus bar  200   d.    
     Accordingly, the number of connecting portions that are formed along the ground bus bar  200   d  is the same as the sum of the connecting portions that are formed along the U-bus bar  200   a , the V-bus bar  200   b , and the W-bus bar  200   c.    
     Referring to  FIG. 3 , the connecting portion  300  is formed by incising one side of the U-bus bar  200   a  to be integrally formed therewith, and the connecting portion  300  includes a first extension portion  300   a , a bent portion  300   b , and a second extension portion  300   c.    
     The first extension portion  300   a  is extended in a central portion of the central distribution unit  100 , and the second extension portion  300   c  is bent to be at a predetermined acute angle with the first extension portion  300   a.    
     The inner surface of the bent portion  300   b  where the first extension portion  300   a  and the second extension portion  300   c  are connected corresponding to an outer circumference of the wire has a predetermined radius along one part of a circle. 
     Referring to  FIG. 2  and  FIG. 3 , the U-terminal  110   a , the V-terminal  110   b , and the W-terminal  110   c  are respectively integrally formed on the U-bus bar  200   a , the V-bus bar  200   b , and the W-bus bar  200   c , and the respective connecting portions  300  are integrally formed between them. 
     Accordingly, because the shapes thereof are different from each other, it is desirable that a separate mold is used to form the respective bus bars in an exemplary embodiment of the present invention. 
       FIG. 4  is a partial top plan view of a central distribution unit that is mounted in a motor unit according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 4 , a wire  400  is in surface contact with the inner surface  410  of the bent portion  300   b  between the first extension portion  300   a  and the second extension portion  300   c  in the connecting portion  300  that is formed on the U-bus bar ( 200   a ) and is welded thereto. 
     The wire  400  has a section of a predetermined radius, and the bent portion  300   b  is bent to have the predetermined radius along the outer circumference of the wire  400 . 
     If the angle that the first bent portion  300   b  and the second bent portion  300   b  crosses is larger than 90 degrees, the wire  400  can be separated from the bent portion, but because the angle is, e.g., 60 degrees that is smaller than 90 degrees, the wire between the first bent portion  300   b  and the second bent portion  300   b  can be securely positioned. 
     Accordingly, the wire  400  can be easily welded to the bent portion  300   b , and the welding portion  410  is firmly fixed thereto after the welding process. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.