Electromagnetically released spring applied friction brake with torque booster
First Claim
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1. A friction braking arrangement comprising:
- at least one rotatable member to be braked;
a stationary ferromagnetic housing mounted adjacent to said at least one rotatable member;
a ferromagnetic armature interposed said rotatable member and said stationary ferromagnetic housing and means mounting said armature to said housing for relative axial movement while restraining said armature against free relative rotation;
spring operator means interposed said armature and said ferromagnetic housing for generating a force acting on said armature tending to urge said armature axially away from said housing;
friction engagement means for creating a frictional breaking force on said at least one rotatable member by the urging of said armature away from said stationary housing;
electromagnetic means mounted in said ferromagnetic housing and acting when energized, for urging said armature axially towards said ferromagnetic housing with a force nullifying said spring operator force; and
torque booster means comprising non self-energizing camming means reacting to the torque reaction generated by said friction engagement means to increase the axial engagement force only when said spring operator force is exerted on said armature, whereby the increased axial engagement force increases the torque capacity of said brake arrangement, said camming means comprising conical ballrecess engagement means interposed said at least one of said rotatable member and at least another of said rotatable members.
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Abstract
A compactly sized spring-applied electromagnetically released radial face friction brake, with a ball-pocket torque booster producing increased torque capacity. The friction brake is released by energization of an electromagnetic coil attracting an axially movable armature, which nullifies the spring operator force to release the brake. A fail safe electric motor brake application of the brake includes a friction surface mounted to the cooling fan rotated by the electric motor armature to aid in dissipating the heat energy developed in braking.
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Citations
10 Claims
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1. A friction braking arrangement comprising:
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at least one rotatable member to be braked; a stationary ferromagnetic housing mounted adjacent to said at least one rotatable member; a ferromagnetic armature interposed said rotatable member and said stationary ferromagnetic housing and means mounting said armature to said housing for relative axial movement while restraining said armature against free relative rotation; spring operator means interposed said armature and said ferromagnetic housing for generating a force acting on said armature tending to urge said armature axially away from said housing; friction engagement means for creating a frictional breaking force on said at least one rotatable member by the urging of said armature away from said stationary housing; electromagnetic means mounted in said ferromagnetic housing and acting when energized, for urging said armature axially towards said ferromagnetic housing with a force nullifying said spring operator force; and torque booster means comprising non self-energizing camming means reacting to the torque reaction generated by said friction engagement means to increase the axial engagement force only when said spring operator force is exerted on said armature, whereby the increased axial engagement force increases the torque capacity of said brake arrangement, said camming means comprising conical ballrecess engagement means interposed said at least one of said rotatable member and at least another of said rotatable members. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fail safe braking arrangement for an electric motor of the type having a cooling fan and a motor casing, comprising:
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a stationary ferromagnetic brake housing fixed to said motor casing, said housing having a radial face; an electromagnetic coil mounted in said housing; an axially movable ferromagnetic armature disposed adjacent to said radial face of said housing; an annular friction surface mounted to said motor fan and mounted adjacent to said armature so as to be frictionally engaged by said armature; spring operator means for urging said armature away from said radial face of said housing and into engagement with said annular friction surface; torque booster means comprising non self-energizing camming means reacting to the brake torque generated by said spring operator means to increase the engagement pressure between said armature and said further surface, said camming means comprising conical ball-recess engagement means interposed said armature and said housing; and means for energizing said coil when said electric motor is energized so as to create an attractive force on said armature and thereby nullifying said operator spring force to release said brake. - View Dependent Claims (10)
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9. The electric motor brake unit according to claim 9 wherein said conical ball-recess engagement means includes a plurality of ball elements and corresponding plurality of pockets formed respectively in said radial faces of said armature and said housing, said pockets aligned with each other to form conical pocket pairs, each of said ball elements disposed in a pocket pair.
Specification