Tape measure with epicyclic gear drive for tape retraction
AssigneeMilwaukee Electric Tool Corporation
InventorsJonathan F. Vitas, Devin W. Herritz, Scott Earl McKinster
Life of this patent
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Abstract
A tool, such as a tape measure, including a spring-based retraction system is shown. The retraction system utilizes an epicyclic gear train coupled between the tape blade winding reel and a rotating arbor or axle within the tape measure. A spiral spring has an outer end coupled to the reel and an inner end coupled to the axle. The gear train may be a reduction gear train such that the axle rotates slower than the reel. By coupling the spiral spring between the gear train input and gear train output, high energy density springs may be used, which may allow for decrease in housing size, increase in tape length or thickness for a given housing size, and/or advantageous retraction speed control.
Claims20
A tape measure comprising:
- a housing;
- an axle rotatably mounted within the housing;
- a tape reel rotatably mounted within the housing around the axle, the tape reel comprising a radially outward-facing surface;
- an elongate tape blade wound around the radially outward-facing surface of the tape reel, both the axle and the tape reel rotating within the housing during extension and rewinding of the elongate tape blade with respect to the housing;
- a hook coupled to an outer end of the elongate tape blade;
- a retraction system configured to drive rewinding of the elongate tape blade on the tape reel;
- and
- a gear train comprising an input coupled to the tape reel and an output coupled to the axle, wherein the retraction system and the gear train are configured to provide a pre load torque between the tape reel and the axle between 0.5 and 2.5 in-lbf.
A tape measure comprising:
- a housing;
- an axle rotatably mounted within the housing;
- a tape reel rotatably mounted within the housing around the axle, the tape reel comprising a radially outward-facing surface;
- an elongate tape blade wound around the radially outward-facing surface of the tape reel, both the axle and the tape reel rotating within the housing during extension and rewinding of the elongate tape blade with respect to the housing;
- a hook coupled to an outer end of the elongate tape blade;
- a retraction system configured to drive rewinding of the elongate tape blade on the tape reel;
- and
- a gear train comprising an input coupled to the tape reel and an output coupled to the axle;
- wherein a maximum torque generated by the retraction system reacting between the tape reel and the axle is between 3 and 20 in-lbf.
A tape measure comprising:
- a housing;
- an axle rotatably mounted within the housing;
- a tape reel rotatably mounted within the housing around the axle, the tape reel comprising a radially inward-facing surface defining an interior reel cavity and a radially outward-facing surface;
- an elongate tape blade wound around the radially outward-facing surface of the tape reel;
- a spring located within the interior reel cavity, the spring comprising an outer end coupled to the tape reel and an inner end coupled to the axle, wherein, when the elongate tape blade is unwound from the tape reel to extend from the housing, the spring stores energy, and the spring releases energy driving rewinding of the elongate tape blade on to the tape reel;
- a retraction system configured to drive rewinding of the elongate tape blade on the tape reel;
- and
- a gear train comprising an input coupled to the tape reel and an output coupled to the axle;
- wherein during extension of the elongate tape blade from the housing, a ratio of tape reel rotations to axle rotations is greater than 1.1:1 and less than 1.6:1.
Dependencies are inferred from the claim text.