Brush construction for a small electrodynamic machine

Claim 2

In an electrodynamic machine including a frame having a spring-engaging first reference point, an assembly for holding a brush against a commutator, the assembly comprising at least one arm having a first end part pivotally secured to the frame, a remote part holding the brush, and a second reference point along the length of said arm, the assembly further comPrising a leaf spring which is generally flat in its unloaded condition defining an initial length between its ends, this spring when assembled being bowed under a buckling load whereby the spring has a first end secured to the frame at said first reference point and the spring has a remote part engaging the arm at said second reference point, the distance between said two points being less than said initial spring length, the spring so loaded exerting a force on the arm both axially along the length thereof and laterally relative to said pivot and thereby resiliently positioning and urging the brush against the commutator, said spring having a spring characteristic which is very level within a comparatively wide range of spring deflection.

Claim 3

In an electrodynamic machine including a frame having a spring-engaging first reference point, an assembly for holding a brush against a commutator, the assembly comprising at least one arm having a first end part pivotally secured to the frame, a remote part holding the brush, and a second reference point along the length of said arm, the assembly further comPrising a leaf spring which is generally flat in its unloaded condition defining an initial length between its ends, this spring when assembled being bowed under a buckling load whereby the spring has a first end secured to the frame at said first reference point and the spring has a remote part engaging the arm at said second reference point, the distance between said two points being less than said initial spring length, the spring so loaded exerting a force on the arm both axially along the length thereof and laterally relative to said pivot and thereby resiliently positioning and urging the brush against the commutator, said spring having a spring characteristic which is very level within a comparatively wide range of spring deflection.

Claim 4

In an electrodynamic machine including a frame having a spring-engaging first reference point, an assembly for holding a brush against a commutator, the assembly comprising at least one arm having a first end part pivotally secured to the frame, a remote part holding the brush, and a second reference point along the length of said arm, the assembly further comPrising a leaf spring which is generally flat in its unloaded condition defining an initial length between its ends, this spring when assembled being bowed under a buckling load whereby the spring has a first end secured to the frame at said first reference point and the spring has a remote part engaging the arm at said second reference point, the distance between said two points being less than said initial spring length, the spring so loaded exerting a force on the arm both axially along the length thereof and laterally relative to said pivot and thereby resiliently positioning and urging the brush against the commutator, said spring having a spring characteristic which is very level within a comparatively wide range of spring deflection.

Claim 5

Apparatus according to claim 1 wherein the frame defines an aperture through which the first part of the arm extends externally, whereby said first end is manually removable from the frame.

Claim 6

In an electric motor including a frame having a spring-engaging first reference point, and commutator and brush elements, the improvement in combination therewith of an assembly for holding each brush against the commutator, comprising for each brush an arm having a first end-part pivotally secured to the frame, a remote part holding the brush, and a second reference point along the length of said arm, and a leaf spring which is generally flat in its unloaded condition defining an initial length between its ends, this spring when assembled being bowed under a buckling load whereby the spring has a first end secured to the frame at said first reference point and the spring has a remote part engaging the arm at said second reference point, the distance between said two points being less than said initial spring length, the spring exerting a force on the arm both axially along the length thereof and laterally relative to said pivot and thereby resiliently positioning and urging the brush against the commutator, said spring having a spring characteristic which is very level within a comparatively wide range of spring deflection.

Claim 7

In an electric motor including a frame having a spring-engaging first reference point, and commutator and brush elements, the improvement in combination therewith of an assembly for holding each brush against the commutator, comprising for each brush an arm having a first end-part pivotally secured to the frame, a remote part holding the brush, and a second reference point along the length of said arm, and a leaf spring which is generally flat in its unloaded condition defining an initial length between its ends, this spring when assembled being bowed under a buckling load whereby the spring has a first end secured to the frame at said first reference point and the spring has a remote part engaging the arm at said second reference point, the distance between said two points being less than said initial spring length, the spring exerting a force on the arm both axially along the length thereof and laterally relative to said pivot and thereby resiliently positioning and urging the brush against the commutator, said spring having a spring characteristic which is very level within a comparatively wide range of spring deflection.

Claim 8

Apparatus according to claim 3 wherein said spring has a spring characteristic which is very level within a comparatively wide range of spring deflection.

Claim 9

Apparatus according to claim 3 wherein said pivoted engagement of said first end part comprises a knife-edge bearing.

Claim 10

Apparatus according to claim 3 wherein the frame defines an aperture through which the first part of the arm extends externally, whereby said first end is manually removable from the frame.