The present invention relates generally to motors, and more particularly to a DC (direct current) motor, to a brush holder for a DC motor, and to a system including a DC motor and including an assembly having a component operatively driven by the motor.
Conventional DC motors include a DC motor having a rotatable armature shaft. The motor includes an armature core which is attached to the armature shaft and which is surrounded by non-rotating permanent magnets attached to a motor housing. An armature winding is attached to, and axially extends beyond, the armature core. The armature winding is connected to a commutator which rotates with the armature shaft. Non-rotating brushes are connected to a DC power source and make contact with the commutator which causes the armature shaft to rotate as is known to those skilled in the art. Designs are known which have two motor-shaft support bearings located on the same side of the armature core. Other designs are known wherein radially outwardly extending brushes contact radially inwardly extending surfaces of a commutator which is attached to an overhanging portion of the armature core. Brush holders are known which include a metallic brush holder body located in an electrically-insulated portion of the motor housing.
What is needed is an improved DC motor, an improved brush holder for a DC motor, and an improved system including a DC motor and including an assembly having a component operatively driven by the motor.
A first expression of an embodiment of the invention is for a brush holder for a DC motor wherein the brush holder includes flexible first and second elongated electrical conductors and includes an elongated, flexible, electrically-insulative brush-holder body. The first and second elongated electrical conductors each have a proximal end and a distal end. The brush-holder body: separately surrounds, and is strip-molded to, the first and second elongated electrical conductors; extends from at least proximate the proximal end to past the distal end of each of the first and second elongated electrical conductors; and has a distal end portion which surrounds the distal ends of the first and second elongated electrical conductors and which includes first and second brush recesses.
A second expression of an embodiment of the invention is for a DC motor including a rotatable armature shaft, an armature core, an armature winding, first and second support bearings, and a commutator and a brush holder. The armature shaft has a central longitudinal axis. The armature core has a first core portion attached to the armature shaft and has a second core portion which is attached to the first core portion, which extends axially from the first core portion, and which is spaced radially outwardly apart from the armature shaft. The armature winding is attached to the first and second core portions, has a first winding portion extending axially beyond the first core portion, and has a second winding portion extending axially beyond the second core portion. The first and second support bearings are operatively connected to the armature shaft, wherein the second support bearing is disposed between the first support bearing and the first core portion and wherein the first winding portion at least partially axially overlaps the second bearing. The second winding portion at least partially axially overlaps the commutator and the brush holder.
A third expression of an embodiment of the invention is for a motor system including a DC motor and an assembly. The DC motor includes: a motor housing; a rotatable armature shaft; an armature core attached to the armature shaft and disposed within the motor housing; a motor end plate having a central opening and covering the motor housing, wherein the armature shaft extends from the central opening; and a motor-associated support bearing operatively attached to the motor end plate and to the armature shaft. The assembly includes: a component operatively driven by the motor; an assembly housing; and an assembly-associated support bearing operatively attached to the assembly housing and to the armature shaft.
Several benefits and advantages are derived from one or more of the expressions of an embodiment of the invention. In one example, the strip-molded brush holder avoids the manufacturing complexities of conventional metallic brush holders. In the same or a different example, having the second winding portion at least partially axially overlap the commutator and the brush holder and having the two support bearings located on the other side of the armature core shortens the axial length of the DC motor (the combined axial length of the motor housing and the motor end plate) compared to conventional motor designs. In the same or a different example, having the first winding portion at least partially axially overlap the second support bearing shortens the axial length of the motor system.
Referring now to the drawing,
In one enablement of the first expression of the embodiment of
In one choice of materials of the first expression of the embodiment of
A second expression of the embodiment of
In one construction of the embodiment of
In one enablement of the second expression of the embodiment of
A third expression of the embodiment of
In one enablement of the third expression of the embodiment of
Several benefits and advantages are derived from one or more of the expressions of an embodiment of the invention. In one example, the strip-molded brush holder avoids the manufacturing complexities of conventional metallic brush holders. In the same or a different example, having the second winding portion at least partially axially overlap the commutator and the brush holder and having the two support bearings located on the other side of the armature core shortens the axial length of the DC motor (the combined axial length of the motor housing and the motor end plate) compared to conventional motor designs. In the same or a different example, having the first winding portion at least partially axially overlap the second support bearing shortens the axial length of the motor system.
The foregoing description of several expressions of an embodiment of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.