Method Of Assembly Of An Electrical Brush And Terminal Member

Abstract

An electrical snap-in terminal and brush housing and method of assembly are disclosed. The terminal blade member is provided with a plurality of mutually opposed resilient tongues arranged to contactively abut wall means of the brush housing to retain, in a first or blade insertion direction, the terminal blade member within the brush housing. The terminal blade member is also provided with an enlarged shoulder portion to define the position of the terminal blade member within the brush housing in a second or brush insertion direction. In order to aid in the assembly of the brush means within the brush housing, the housing includes an open end portion having the dimensions of a substantial portion of the terminal blade member so that the terminal blade member may itself be used to compressively confine the brush biasing means and, once the biasing means are sufficiently compressed, the brush housing is provided with means to receive the terminal blade member within suitably provided structure comprising a slot and notches in the brush housing so that the terminal blade member will be removably secured within the housing.

Parent Case Text

This is a division of application Ser. No. 362,628, filed May 21, 1973.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to the field of brush housings and snap-in terminal blade members usable for example in dynamoelectric machines having externally loaded electrical brushes. In particular, the present invention is directed to a unitary terminal blade member which may be used as the compressing tool to compressively confine a resiliently biased electrical brush means within a brush housing and which is not orientation sensitive upon insertion into the brush housing.

2. Description of the Prior Art

The prior art, particularly as illustrated in my copending commonly assigned patent application Ser. No. 306,778 titled "Dynamoelectric Machine End Plate And Mounting Means", and as reproduced in FIGS. 1, 2 and 3 of the instant patent application, illustrates a relatively simple, inexpensive and reliable terminal blade member construction and brush housing construction. The terminal blade member is comprised of a unitary stamping of suitable conductive metal such as, for example, copper or aluminum and is provided with a pair of resilient tongue or finger elements which extend from the side of the terminal blade member to provide an abutment engaging means for retaining the terminal blade member within the brush housing. The brush housing is provided with a brush channel extending therethrough in one direction and a terminal blade channel extending therethrough in a second direction which is substantially perpendicular to the one direction. The two channels are of substantially equal width.

This structure presents two major problems. Firstly, assembly of the brush, brush biasing means and terminal blade member within the brush housing is complicated. The brush and brush biasing means must be inserted within the brush channel. The brush biasing means must be compressed by the use of a blunt tool and while compressed, the terminal blade member must be inserted within the terminal blade channel. In the event of improper alignment or premature withdrawal of the compressing tool, the terminal blade member will be improperly received within the terminal blade member channel. In the instance of those brush housings which are formed of a molded plastic, improper insertion of the terminal blade may also result in fracturing of portions of the housing. The integrity of these housing portions is relied upon to provide the abutment member for the resilient terminal blade fingers or tongues to retain the terminal blade within the housing. This problem has resulted in a significant number of field failures of dynamoelectric machines using this structure since the fractured housing may not be immediately detectable.

The second problem, which is somewhat related to the first problem, resides in the fact that the unitary terminal blade member having the projecting resilient fingers tends to be a one directional device. That is, the terminal blade member must be inserted within the terminal blade member channel of the brush housing with the resilient fingers directed away from brush member so that the combination of forces from the brush biasing means and the resilient fingers cause those tongues or fingers to engage the abutment means of the walls of the brush housing. Insertion with an opposite orientation will result in the brush biasing means urging the resilient fingers away from the abutment means resulting in a loose or impositive terminal connection. This also results in a significant number of field failures making the resulting structure relatively expensive since field failure replacements involve replacing the entire dynamoelectric machine. It is, therefore, an object of the present invention to provide an improved terminal blade member. It is also an object of the present invention to provide an improved brush housing. It is a further object of the present invention to provide an improved method of assembly of the new terminal blade and the new brush housing. It is a specific object of the present invention to provide a unitary terminal blade member which may be inserted within the terminal blade member receiving channel or slots in any of the possible positions. It is also a specific object of the present invention to provide a terminal blade member which may itself replace the compressing tool in the assembly stage thereby simplifying the assembly process. It is also a specific object of the present invention to provide an improved brush housing structure which may be of molded plastic in which assembly forces and misalignment will not subject the housing to fracturing and resultant field failures.

SUMMARY OF THE PRESENT INVENTION

The present invention provides an improved terminal blade member which is of unitary structure. The terminal blade member comprises a brush biasing wall portion for receipt within the brush housing and a conductor receiving portion having a pair of shoulders extending laterally to a greater extent than the brush biasing wall portion. The brush biasing wall portion is provided with front and rear wall elements each of which is provided with at least one resilient finger or tongue member directed generally toward the conductor receiving portion and extending away from the terminal blade member. The conductor receiving portion of the terminal blade member is further provided with a pair of spacer elements which are directed generally perpendicular to the conductor receiving portion and located at the laterally extending shoulders.

The brush housing is provided with a brush channel and with a terminal blade channel. The brush channel is substantially open, or U-shaped, from the brush insertion end up to the terminal blade channel and is provided with a pair of cover wall means from the terminal blade channel inwardly to assist in confining the brush and brush biasing means. The terminal blade channel is further provided with a pair of outwardly facing notches. The notches cooperate with the shoulders of the conductor receiving portion and with the spacer elements to define the position of the terminal blade member within the housing in the brush insertion direction while the finger elements of the terminal blade member and the cover wall portion cooperate to define the position of the terminal blade member within the brush housing in the blade insertion direction. By providing a substantially open, or U-shaped, brush insertion region, the terminal blade member may be used as the compressing tool and when the resilient means are sufficiently compressed, the terminal blade member may be inserted so that its remote end is within a slot provided therefor in the rear wall of the brush channel and the shoulders and spacer elements are within the notches provided therefor in the housing.

The terminal blade member according to the present invention thus can be seen to cooperate with the brush housing of the present invention to define an assembly in which the orientation of the terminal blade member with respect to the brush housing is bidirectional and which, following assembly is relatively rigid in character. It will also be appreciated that, until the final terminal blade snap-in, the forces encountered in the assembly process will be almost exclusively applied in the direction of the major axis of the brush channel thereby avoiding any application of forces of a character which could cause fracturing or splitting of the brush housing and the resulting field failures. By providing a terminal blade member having dimensions which substantially correspond to the dimensions of the receiving location provided therefor on the brush housing, misalignment problems resulting in field failures are readily avoided.

By providing the terminal blade member with a first portion which substantially corresponds in dimensions to the insertion region of the brush channel, the terminal blade member readily functions initially as the biasing means compressing tool eliminating the need for an additional compression tool thereby facilitating assembly. Furthermore, by providing a substantially open U-shaped insertion region for the brush and brush biasing means, the assembly process is greatly facilitated while a source of field failure problems, that is, the relatively unsupported overhanging cover wall structure in this region according to the prior art brush housing, has been eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates, in a partial elevational view, a molded plastic brush housing according to the prior art.

FIG. 2 illustrates, in an elevational view, a terminal blade member for use with the brush housing of FIG. 1.

FIG. 3 illustrates, in a sectional view, the terminal blade member of FIG. 2 and the brush housing of FIG. 1 in assembled relationship.

FIGS. 4 and 5 illustrate, in an elevational view and in a perspective view, a terminal blade member according to the present invention.

FIG. 6 illustrates, in a partial elevational view, a molded plastic brush housing according to the present invention.

FIG. 7 illustrates, in a sectional view, the terminal blade member of FIGS. 4 and 5 and the brush housing of FIG. 6 in assembled relationship.

FIGS. 8, 9, 10 and 11 illustrate, in perspective views the sequence of steps in the method of assembly of the terminal blade member of FIGS. 4 and 5 in the brush housing of FIG. 6 according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIG. 1 illustrates a partial elevational view of a dynamoelectric machine end plate structure 10 according to my above-noted copending patent application Ser. No. 306,778. The end plate structure 10 is formed of a molded resinous or plastic material and is provided with an electrical brush housing denoted generally at 12. The brush housing 12 is comprised of a rear wall portion and a pair of upwardly extending L-shaped wall members 14 which are arranged to be facing one another so that the portions 16 which extend toward one another define cover wall means for a brush channel 18. A terminal blade channel 20 is formed by removing a small section of each of the cover wall means 16 and by forming a matching slot or hole in the rear wall portion in alignment with the removed sections of the cover wall means. The channels 18 and 20 extend generally perpendicularly to one another.

Referring now to FIG. 2, a terminal blade member 22 according to the prior art is illustrated. The terminal blade member 22 is formed of a unitary piece of suitable metallic construction, such as for example, copper or aluminum and is arranged to be of substantially uniform width for insertion into the channel 20 of the brush housing 12 of FIG. 1. The terminal blade member is provided with a conductor receiving portion denoted generally as 24 having a first and a second conductor securing portions 26, 28 which extend generally perpendicularly away from the conductor receiving portion 24. Terminal blade member 22 is also provided with a brush retaining portion denoted generally as 30. A pair of resilient finger elements or tongues 32 are formed integral with the retaining portion 30 and extend generally toward the conductor receiving portion 24. Tongues 32 are at a slight angle with respect to the retaining portion 30 so that their free ends may extend laterally away from the main portion of terminal blade member 22. The terminal blade member 22 is provided with a width dimension which substantially coincides with the width of the terminal blade receiving channel 20 to provide uniform biasing of the electrical brushes as described hereinbelow.

Referring now to FIG. 3, the terminal blade member 22 is shown received within the terminal blade channel 20 of the brush housing 12 in a sectional view taken approximately along the middle of brush channel 18. The view also illustrates a brush member 34 and a brush biasing means 36 received within brush channel 18. In preparing the assembly illustrated in FIG. 3, the brush 34 and brush biasing means 36 would be inserted within brush channel 18 from the insertion, or radially remote, end 38 with the brush 34 being in abuting contact with a slip ring member, now shown. "Radial" is intended to mean radial with respect to the axis of rotation of the associated slip ring. The brush biasing means 36 would be compressed through the use of a separate compressing tool to a depth sufficient to provide that the radially extreme end of biasing means 36 was below, relative to FIG. 3, the terminal blade channel 20. Terminal blade member 22 would be inserted within the opening of terminal blade channel 20 and would be inserted part way within housing 12 so as to engage a major portion of the end of brush biasing means 36. The tool would than be removed and the terminal blade member 22 would be inserted the rest of the way through terminal blade channel 20. As shown in FIG. 3, resilient finger member 32 is arranged to abut wall portion 40 of the cover wall 16. Due to the biasing action of resilient means 36, terminal blade member 22 must be oriented with the finger elements 32 extending away from the brush member 34. If the terminal blade member 22 were inserted with the finger elements 32 directed toward brush member 34, the reaction force of the brush biasing means 36 would prevent finger element 32 from engaging any abutment surface and the terminal blade member 32 would then rely solely upon frictional loading between the terminal blade member 22 and the side wall of terminal blade channel 20 for retention of terminal member 22 within terminal blade channel 20. Furthermore, as discussed hereinabove, misalignment of terminal blade member 22 upon insertion into terminal blade channel 20 and/or excessive assembly forces could result in fracturing of the brush housing channel particularly in the area of wall portion 40 of cover wall 16 so that the reaction force of brush biasing means 36 eventually would remove the material from this region and the brush would no longer be biased toward its associated slip ring.

Referring now to FIGS. 4 and 5, the terminal blade member according to the present invention and designated generally as 50 is shown in an elevational view, FIG. 4, and in a perspective view FIG. 5. Terminal blade member 50 is also comprised of a conductor receiving portion 52 and a brush retaining means 54. Conductor receiving portion 52 includes a pair of elements 56, 58 which extend generally perpendicularly away from the main portion of the conductor receiving portion 52 and are analogous to the elements 26, 28 described hereinabove with reference to FIG. 2. Conductor receiving portion 52 is further provided with a pair of extending shoulders 60 which extend substantially beyond, in terms of width, the brush retaining means 54. Shoulders 60 are further provided with a pair of spacer elements 62 which are formed to extend substantially at right angles from shoulders 60 and whose function will be more fully described hereinbelow.

Retaining means 54 is provided with a front wall portion 64 and a rear wall portion 66. The terms "front" and "rear" are merely for purposes of differentiation. The front and rear wall portions 64, 66 are formed by bending or folding a substantially planar terminal blade portion, as at 68, through a substantially 180.degree. bend to form the front and rear wall portions 64, 66 of retaining portion 54. Retaining portion 54 is provided with a plurality of finger elements or tongues 70 with each of the front and rear wall portions 64, 66 being provided with preferably two each of finger elements 70. The finger elements 70 are substantially analogous to the prior art finger elements 32 and are similarly situated and formed.

Terminal blade member 50 retains the ease of formation of the prior art terminal blade member 20 (FIG. 2). Spacers 62 extending from the conductor receiving portion 52 in the same general direction as the conductor retaining portions 56, 58 may be formed in the same formation process. Finger elements or tongues 70 may be formed in a fashion similar to the formation of the tongues 32 of the FIG. 2 terminal blade member. The terminal blade member 50 would be provided with the bend 68 as a final formation step. This process can be readily automated on existing equipment by well known techniques.

Referring now to FIG. 6, the brush housing 72 according to the present invention is illustrated. As shown the brush housing is formed of a molded resinous or plastic material on an end plate member 10 which is substantially identical with that illustrated in FIG. 1. The brush housing 72 has a back wall member, a pair of side wall members 74 and a pair of cover wall members 76. The cover wall members 76 extend toward one another from the side walls 74 to define a pair of substantially L-shaped wall structures. A brush channel 77 is thereby formed. In order to accomplish the specifics of the present invention, the cover wall members 76 do not extend radially to the brush insertion region 82. Further, side wall members 74 are provided with a pair of notches 78 each of which have an inner edge 79 in alignment with the radially outer edge of the associated cover wall member 76. In order to provide additional lateral support for the brush housing, each side wall 74 is provided with a support wall 80 circumferentially located on the end plate member 10 in the vicinity of the notches 78. It can be seen by inspection, comparing the FIGS. 1 and 6, that whereas the side walls 14 of the prior art brush housing were uninterrupted, the side walls 74 of the brush housing according to the present invention are notched as at 78 to receive portions of the snap-in terminal blade member and in particular the shoulders 60 and the spacing elements 62 of the terminal blade member 50 according to the present invention. Furthermore, to facilitate assembly and avoid field failure problems, the cover wall means 76 do not extend radially beyond the inner edge 79 of notches 78 whereas the prior art taught that the cover walls extend into the brush insertion region 82 (where they are identified as 40 in FIG. 1).

Referring now to FIG. 7, the terminal blade member 50 is illustrated in assembled relationship within the brush housing 72. FIG. 7 is a sectional view taken approximately along the radial center line of brush channel 77 similarly to the FIG. 3 view. FIG. 7 also shows a brush member 34 and a brush biasing means 36 received within brush housing 72 and confined by terminal blade member 50. The portion of terminal blade member 50 in the vicinity of the 180.degree. fold 68 is received within a suitably provided slot or void 84 within the rear wall of brush housing 72 comparable to that illustrated in FIG. 3 but having a substantially larger radial dimension. The resilient finger member 70 which is in proximity to the biasing means 36 is shown to be in abuting contact with the cover wall means 76 while the finger element 70 which is more remote from the biasing means 36 is not in use. Shoulders 60 and spacer elements 62 of the terminal blade member according to FIGS. 4 and 5 are received within notches 78 to define in cooperation with the resilient finger 70 in contact with the cover wall means 76 a relatively rigid removably secured position for the terminal blade member 50 within brush housing 76 which does not rely upon the resilient bias of the biasing means 36 or any frictional contact to maintain position.

By providing the terminal blade member 50 with the widened shoulder 60 and the generally radially directed spacer elements 62 and by further providing a brush housing 72 having notches 78 for receipt of the shoulders 60 and spacer elements 62 the present invention provides maximum support (in the radial direction) for the terminal blade member 50 while avoiding the exposure of relatively delicate cantilever plastic material to any stresses which might tend to fracture that material. These elements cooperate to permit the radially generated forces (generated by brush biasing means 36) to be uniformly distributed over relatively thick portions of the side walls 74. By arranging the resilient fingers 70 to engage the cover wall 76 radially inwardly from the terminal blade member 50, the fingers 70 engage cantilever plastic structure which is structurally stronger since it is of substantially greater length and is not subject to radially directed reaction forces.

Referring now to FIGS. 8, 9, 10 and 11, the method of assembly of the terminal blade member 50 within the brush housing 72 is illustrated in a sequence of perspective views which illustrate the various steps involved. For convenience, the brush 34, brush biasing means 36 and electrical connective wiring have been removed from the views in FIGS. 8, 9 and 10 while a portion of the brush housing 72 has been broken away in FIG. 11 to show the final assembly positioning. With the terminal blade member 50 removed from the brush housing 72, as shown in FIG. 8, brush 34 and brush biasing means 36 would be inserted within the brush housing 72 through the entry portion 82 of brush channel 77 so that the brush 34 is in electrical contact with its associated slip ring. Either wall 64, 66 of terminal blade member 50 would then be placed in contact with the free end of brush biasing means 36 and the terminal blade member 50 would be moved in the radial direction to compress brush biasing means 36 at least to the imaginary plane established by inner edges 79 and notches 78. This would place the folded portion 68 of terminal blade member 50 in substantial alignment with the slot or void 84 provided therefor in end plate 10. When the brush biasing means 36 have been sufficiently comprssed, as illustrated by the relative position of terminal blade member 50 in FIG. 9, terminal blade member 50 can then be moved to insert folded portion 68 within the slot 84 in the rear wall of the brush housing 72 while concomitently aligning shoulders 60 and spacer elements 62 with the notches 78 as shown in FIG. 10. For ease of assembly, the length of the retaining means 54 of terminal blade member 50 from shoulders 60 to fold 68 should be slightly greater or slightly less than the distance from the top of the notches 78 to the slot or void so that the terminal blade member 50 may have its fold 68 and shoulders 60 inserted within the slot and notches 78 respectively, one at a time. Preferably the length of the retaining means portion 54 will be greater than the distance between the slot and the notches.

Following insertion of folded portion 68 into the void 84, further insertion pressure will compress the resilient finger elements 70 which are on the side of the terminal blade member 50 in the direction of brush 34 so that the terminal blade member 50 can be fully inserted. At full insertion shoulders 60 and spacer elements 62 will be received within notches 78 and the resilient fingers 70 will no longer be compressed and the free ends of the finger elements 70 will move toward the brush 34 to thereby move behind cover wall means 76. Terminal blade member 50 will thereby become removably secured within the brush housing 72. FIG. 11 illustrates the final assembled position relationship in a perspective view with a portion of brush housing 72 broken away. Conductor means 86 in the conductor receiving portion 52 is included in this view.

It can be seen that the structure according to the present invention provides a terminal blade member 50 which may be inserted within the brush housing 72 in either of two directions making it position insensitive while further providing a structure which permits the use of terminal blade member 50 as the compressing tool for compressing the resilient brush biasing means 36 thereby facilitating assembly of the terminal blade member brush housing.

Claims

What I claim is:

1. A method of assemblying a resiliently biased electrical brush within a brush housing comprising the steps of:

inserting in a first direction the brush and biasing means within the housing;

compressing the biasing means with an end of the terminal blade member to a degree sufficient compress all of the biasing means between the brush and an imaginary plane defined by the terminal blade member final position;

sliding the terminal blade member generally perpendicular to the first direction until the end of the blade member enters a slot provided therefor in said housing and the shoulders of said blade member are aligned with notches provided therefor in said housing; and

forcing said blade member end and said shoulders into said slot and notches, respectively, until resilient fingers of said terminal blade member move freely behind wall means of said housing.

2. The method of claim 1 wherein the step of forcing said blade member end and said shoulders is continued until widened shoulder portions abut the bottom of the housing notches.

3. The method of claim 1 wherein the step of sliding includes the step of rotating the terminal blade member to a position substantially perpendicular to the first direction to further compress the brush biasing means after the end of the terminal blade member has entered the slot.

4. The method of claim 1 wherein the terminal blade member has two substantially identical oppositely deposed brush biasing wall portions and the step of compressing includes the step of orienting either of the brush biasing wall portions to generally directed toward the brush.

5. A method of assemblying a resiliently biased electrical brush within a brush housing comprising the steps of:

inserting the brush and brush biasing means with a housing channel in a first direction;

contacting the free end of the brush biasing means with a brush biasing wall portion of a terminal blade member, the brush biasing wall portion being generally perpendicular to the first direction;

forcing the terminal blade member in the first direction to apply a compressive force to the brush biasing means;

aligning the end portion of the terminal blade member with a slot provided therefor in a wall of the brush housing while aligning shoulder portions of the terminal blade member with notches provided therefor in opposite walls of the brush housing; and

forcing the terminal blade member in a direction perpendicular to the first direction to cause the terminal blade member end portion and shoulder portions to enter the slot and notches, respectively.

6. The method of claim 5 wherein the step of forcing includes the step of moving the terminal blade member in the direction perpendicular to the first direction until resilient fingers on said terminal blade member move behind wall means of the brush housing.