BRUSH HOLDER ASSEMBLY

Abstract: A brush holder (20) for a four pole single speed motor is fabricated from three separate elements, a base member (22) with a central aperture (26) having 4 elongated slots (28) extend equally and angularly from the central aperture (26) and inner and outer bus bars (38, 40). Each bus bar has a pair of brush boxes (30) integrally connected by a bus bar plate (44). The brush boxes (30) are spaced from the plane of the bus bar plate (44) at a distance substantially equal to the thickness of the base member (22). The bus bars are positioned in slots and held there by means of a pressed fit relationship between the brush boxes and the slots. Flat spring means (64) bias brushes in a first direction toward the center of the aperture.

Description: Brush Holder Assembly This invention relates to a direct current motors in general and more particularly to brush cards for one and two speed four pole permanent magnet motors. Background of the Invention Prior Art US Patent 4,559,465 entitled "Brush Holder Assembly for an Electric Motor" issued to Gagneux, on December 1 7, 1 985, describes a brush holder having a simple flat plate cur or stamped to provide slots for sliding of brushes and openings for holding the brush springs. The springs normally engage the ends of the associated brushes to bias them inwardly towards the motor commutator. When the brushes are retracted, the springs engage the sides of the brushes to lock the brushes in the slots. Summary of Invention It is a principle advantage of the brush holder to minimize the number of parts forming the brush holder to thereby reduce the cost of manufacture. It is an additional advantage to reduce the number of operations in the manufacture of the brush holder. It is still another advantage to provide a modular brush holder that is adaptable to four pole single speed motors and four pole two speed motors. It is yet another advantage to provide efficient cooling for the brushes in the motor. A brush holder for a multi-pole, single speed motor having a base member with a central aperture. Connected at ninety degree intervals to the circumference of the central aperture are elongated slots. An inner bus bar member is resiliently and snapping supported on both sides of the base member in diagonally opposite slots. The brush boxes of the inner bus bar member are on one side of the base member and the integral bus bar plate connecting diagonally opposite brush boxes is on the other side of the base member. An outer bus member is resiliently and snapping supported on both sides of the base member in diagonally opposite slots. The brush boxes of the outer bus bar member are on the one side of the base member and positioned ninety degrees to the brush boxes of the inner bus member. The bus bar plate of the outer bus member is spaced from the bus bar of the inner bus member on the other side of base member. Brushes are mounted in each brush box. Spring means, in the form of a coiled flat spring are mounted on each brush box and positioned to bias each of the brushes in a first direction toward the center of the base member. In order to fabricate a four pole, two speed brush holder a second brush holder is fabricated on a base member having a central aperture with a different diameter than the central aperture of the first base member. The two base members are positioned in parallel to each other with the bus bars facing each other. Between the base member is positioned an insulator preventing electrical connections between the bus bars of the first base member and the bus bars of the second base member. These and other advantages will become apparent from the following drawings and detailed description. Detailed Description of the Drawings In the drawings: Fig. 1 is a plan view of a four pole, single speed brush holder of the preferred embodiment; Fig. 2 is a section view taken along line 2-2 in Fig. 1 ; Fig. 3 is a section view taken along line 3-3 in Fig. 1 ; Fig. 4 is a plan view of the base member of the brush holder of Fig. 1 ; Fig. 5 is a plan view of the inner bus bar of the brush holder of Fig. 1 ; Fig. 6 is a section view taken along line 6-6 in Fig. 5; Fig. 7 is an elevation view taken in the direction of line 7 in Fig. 5; Fig. 8 is an enlarged plan view of the area enclosed in the circle in Fig. 5; Fig. 9 is a section view taken along line 9-9 in Fig. 5; Fig. 10 is a section view taken along line 10-10 in Fig. 5; Fig. 1 1 is a plan view of the outer bus bar of the brush holder of Fig. 1 ; Fig. 12 is a section view taken along line 12-12 in Fig. 1 1 ; Big. 13 is an enlarged plan view of the area enclosed in the circle in Fig. 12; and Fig. 14 is a side view of a four pole, two speed brush holder. Detailed Description Referring to the drawings by the characters of reference there is illustrated in Fig. 1 a plan view of the assembled brush holder 20 of the preferred embodiment. The base member 22, illustrated in Fig. 4, « is fabricated from a non electrically conductive material. The base member 22 has a plurality of apertures such as the apertures 24. A larger central aperture 26 having four elongated slots 28 equally spaced around its periphery provides for the mounting the brush boxes 30. In addition there is a pair of cut outs 32, 34 providing means to locate wiring tabs 36. The wiring tabs 36 are formed at the end of the inner bus bar 38 and the outer bus bar 40 as better illustrated in Figs. 5 and 1 1 . Fig. 10 illustrates the downturned members 42 of the wiring tabs which function to locate any connector, not shown, which is used to attach a circuit wire to the bus bar. Referring to Fig. 5, there is illustrated the formed inner bus bar 38. This bus bar is initially stamped in one flat piece of flexible and resilient electrically conductive material such as copper from which the brush boxes 30 are formed into position. This forms an integral bus bar 38 and brush boxes 30 for the diagonally opposite brush boxes which are electrically connected together through the bus bar plate 44. Each brush box 30 on each of the inner bus bar 38 and the outer bus bar 40 are identical and the same reference characters will be use in the several Figs for clarity and not having all the reference characters in one Fig. Each brush box has a pair of parallel sides 48 which are space to accommodate a brush 50. The top 58 of brush box is formed with a pair of parallel slots 52, shown more clearly in Fig. 8, at one end to accommodate the wire 54 attached to brush 50. The enclosing end wall 56 of the brush box is more clearly illustrated in Fig. 7 and provides for the brush wire 54 to be located and supported. Fig. 1 1 is similar to Fig. 5 with the sole exception that the bus bar plate 60 is formed on a larger radius than the bus bar plate 44. The reason for this is that when the brush holder is assembled, the bus bar plates 44 and 60 are electrically and physically spaced apart. Referring to Fig. 6 and Fig. 12 which are sectional views of the inner and outer bus bars 38 and 40. Integral with the end of the brush box sides 48 is a outwardly formed member 62 which supports a spring means 64 for urging the brush toward the center of the brush holder. The spring means is shown in Fig. 1 , as a coiled flat spring one end of which is contained between the side of the brush box and the formed member 62. The leaf spring extends from the one side 48 of the brush box, down the inside of the brush box to the enclosed end, across the enclosed end and back along the inside of the of the opposite side 48 of the brush box. The other end of the coiled leaf spring is contained between the formed member on the opposite side of the brush box and side of brush box. The brush holder is assembled by taking the inner bus bar 38 and placing it on one side of the base member 22 and have the brush boxes inserted into the elongated slots 28. The flexibility and resiliency of the material will form a sandwich construction with the base member 22 between the bus bar plate 44 and the bottom of the brush boxes 30. The wiring tabs 36 are positioned in the cut out 32. Next the outer bus bar 40 is assembled to the base member in the same way but with the brush boxes positioned ninety degrees from the brush boxes. Again the flexibility and resiliency of the material will form a sandwich construction with the base member 22 between the bus bar plate 60 and the bottom of the brush boxes 30. Thus the completed brush card hold without the brushes 50 and the spring means 64 comprises only three separate members requiring no additional staking to hold the bus bars and the brush boxes in position. The flexibility and resiliency of the material will form a sandwich construction with the base member 22 between the bus bar plate 44 and the bottom of the brush boxes 30. To fabricate a four pole, two speed brush holder as illustrated in Fig. 14, it is necessary to fabricate two substantially identical brush holders as illustrated in Fig 1 . The first bush holder 66 is for high speed and is substantially similar to the brush holder 20 of Fig. 1 . However instead of forming the downturned members 42 of the wiring tabs in a direction opposite the brush boxes as illustrated in Fig. 2, the members are formed in the direction of the brush boxes 30. The central aperture is sized to allow the high speed commutator of the motor to extend therethrough. Additional apertures are formed in the base member of the brush holder 66 to allow the wiring tabs to extend above the top surface of the base member. The second brush holder 68 is formed on a second base member with the central aperture of a different, smaller, size than that of the first base member 66. This is to accommodate the second commutator in the motor. The first and second brush holders 66, and 68 are positioned with their flat sides facing each other with an insulator 70 positioned therebetween. The insulator prevents any electrical shorting between the two brush holders. In each brush holder 20, 66, and 68, the outer peripheral surface of the base members is formed with sufficient irregularities to accommodate the location and fixing of the brush holders in the motor during assembly. A method for assembly a mutli pole brush holder for a four pole single speed motor comprising the steps of fabricating a first base member from an electrically nonconductive material. The base member has a central aperture with four elongated slots extending equally and angularly outwardly from the aperture forming a cross-like pattern. An inner bus bar member is fabricated from an electrically conductive resilient material having a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate. An outer bus bar member is fabricated from an electrically conductive resilient material having a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate. The brush boxes of the inner bus bar member are inserted into opposite ones of the elongated slots on the base member with the brush bar plate flat against one side of the base member and the brush boxes extending away from the other side of base member. The brush boxes of the outer bus bar member are inserted into the remaining elongated slots on the base member with the brush bar plate flat against the one side of the base member and the brush boxes extending away from the other side of base member so that each brush box on the inner bus member is positioned ninety degrees from a brush box on the outer bus member. Spring means are inserted in each brush box and then brushes are inserted in each brush box and against the spring means. To assembly a four pole brush holder for a two speed motor requires the additional steps of fabricating a second base member from a second electrically nonconductive material. The base member has a central aperture with a different diameter than the central aperture of the first base member and includes elongated slots extending equally and angularly outwardly from the aperture. A second inner bus bar member is fabricated from an electrically conductive resilient material and has a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate. A second outer bus bar member is fabricated from an electrically conductive resilient material and has a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate. The brush boxes of the second inner bus bar member are inserted into opposite ones of the elongated slots on the second base member with the brush bar plate flat against one side of the base member and the brush boxes extending away from the other side of the second base member. The brush boxes of the second outer bus bar member are inserted into the remaining elongated slots on the base member with the brush bar plate flat against the one side of the second base member and the brush boxes extending away from the other side of base member. The brush boxes on the second inner bus member are positioned ninety degrees from the brush boxes on the second outer bus member. Spring means are inserted in each brush box and then brushes are inserted in each brush box and against the spring means; Each assembled bus bar member is positioned with the one sides of said first and second base members in a parallel relationship with the central apertures axially inline; and an insulator is positioned between the first and second base members. The insulator has a central aperture that is greater than the central apertures of the first and second base members.

Claims: What is claimed: 1 . A brush holder for a multi-pole, single speed motor having a base member with a central aperture having elongated slots connected at ninety degree intervals to the circumference of the central aperture; an inner bus bar member resiliently and snapping supported on both sides of the base member in diagonally opposite slots, said inner bus bar member having brush boxes on one side of the base member and an integral bus bar plate connecting diagonally opposite brush boxes on the other side of the base member; an outer bus member resiliently and snapping supported on both sides of the base member in diagonally opposite slots, said outer bus member having brush boxes on said one side of the base member and positioned ninety degrees to the brush boxes of the inner bus member and an integral bus bar plate of the outer bus member connecting the diagonally opposite brush boxes spaced from the bus bar of said inner bus member on the other side of said base member. 2. A brush holder for a multi-pole single speed motor according to claim 1 additionally including brushes mounted in each brush box and spring means mounted on each brush box and positioned to bias each of said brushes in a first direction toward the center of said base member. 3. A brush holder for a multi-pole single speed motor according to claim 2 wherein said spring means is a coiled flat spring member. 4. A brush holder for a multi-pole, two speed motor having a first base member having, an inner bus bar member resiliently and snapping supported on both sides of the base member having the brush boxes on one side of the base member and the bus bar plate connecting diagonally opposite brush boxes on the other side of the base member, and an outer bus member resiliently and snapping supported on both sides of the base member having the brush boxes on said one side of the base member positioned ninety degrees to the brush boxes of said inner bus member and the bus bar plate of said outer bus member being spaced from the said bus bar of the inner bus member; a second base member having an inner bus bar member resiliently and snapping supported on both sides of the base member having the brush boxes on one side of the base member and the bus bar plate connecting diagonally opposite brush boxes on the other side of the base member, and an outer bus member resiliently and snapping supported on both sides of the base member having the brush boxes on said one side of the base member positioned ninety degrees to the brush boxes of said inner bus member and the bus bar plate of said outer bus member being spaced from the said bus bar of the inner bus member; and an insulator member positioned between the said other sides of said first and second base members preventing electrical connections between said bus members on said first base member and said bus members on said second base member. 5. A brush holder for a multi-pole two speed motor according to claim 4 additionally including brushes mounted in each brush box and spring means mounted on each brush box and positioned to bias each of said brushes in a first direction toward the center of said base member. 6. A brush holder for a multi-pole two speed motor according to claim 5 wherein said spring means is a coiled flat spring member. 7. A method for assembly a mutli pole brush holder for a motor comprising the steps of fabricating a first base member from an electrically nonconductive material, the base member having a central aperture with elongated slots extending outwardly from said aperture, fabricating an inner bus bar member from an electrically conductive resilient material having a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate; fabricating an outer bus bar member from an electrically conductive resilient material having a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate; inserting the brush boxes of the inner bus bar member into opposite ones of the elongated slots on the base member with the brush bar plate flat against one side of the base member and the brush boxes extending away from the other side of base member ; inserting the brush boxes of the outer bus bar member into the remaining elongated slots on the base member with the brush bar plate flat against the one side of the base member and the brush boxes extending away from the other side of base member so that each brush box on the inner bus member is positioned ninety degrees from a brush box on the outer bus member; inserting spring means in each brush box; and then inserting brushes in each brush box and against the spring means. 8. A method for assembly a mutli pole brush holder for a motor according to claim 7 additionally including the steps of fabricating a second base member from a second electrically nonconductive material, the base member having a central aperture with a different diameter than the central aperture of the first base member with elongated slots extending outwardly from the aperture, fabricating a second inner bus bar member from an electrically conductive resilient material having a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate; fabricating a second outer bus bar member from an electrically conductive resilient material having a pair of brush boxes integrally connected by means of a brush bar plate formed so that the brush boxes are spaced from the bus bar plate; inserting the brush boxes of the second inner bus bar member into opposite ones of the elongated slots on the second base member with the brush bar plate flat against one side of the base member and the brush boxes extending away from the other side of the second base member ; inserting the brush boxes of the second outer bus bar member into the remaining elongated slots on the base member with the brush bar plate flat against the one side of the second base member and the brush boxes extending away from the other side of base member so that each brush box on the second inner bus member is positioned ninety degrees from a brush box on the second outer bus member; inserting spring means in each brush box; inserting brushes in each brush box and against the spring means; positioning the one sides of said first and second base members in a parallel relationship with the central apertures axially inline; and the placing an insulator between the first and second base members, the insulator having a central aperture that is greater than the central apertures of the first and second base members.

Inventors: RUBINCHIK ILYA, RUBINCHIK, ILYA
Applicants: SIEMENS ELECTRIC LTD, SIEMENS ELECTRIC LIMITED
Application year: 1995
Main classification: H02K5
IPC codes: H01R39, H02K5