Tape rule assembly with differential spring-drive systems

Patent metadata

Field	Value
Publication number	US-10870555-B2
Application number	US-201715598479-A
Country	US
Kind code	B2
Filing date	May 18, 2017
Priority date	May 18, 2017
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

A tape rule assembly includes differential spring-drive systems for rotating a reel of tape through an angular distance different from the angular distance traveled by a hub carrying a wound spring, relative to the tape rule housing. The differential spring drive systems include planetary and cycloidal drive systems. The tape rules of the present invention are thus made more compact than conventional tape rules.

First claim

What is claimed is:

1. A tape rule assembly including a length of tape and a wound spring operatively associated with the tape, comprising:
a housing defining an enclosed space; and
a differential spring-drive subassembly rotatably disposed in the housing enclosed space, the differential spring-drive subassembly operative to tighten the spring around a hub when the tape is extended from the housing, wherein the differential spring-drive subassembly includes a cycloidal drive system;
wherein the hub defines a single, self-contained spindle; and
wherein the enclosed space is uninterrupted by any other spindle;
the differential spring-drive subassembly includes a reel supporting the length of tape, the reel and the hub being rotatable about an axis of rotation relative to the housing;
the reel is disposed in the housing concentrically about the hub; and
wherein the reel and the hub are operatively associated with the housing so that, when the tape is extended from the housing, the reel rotates through a first angular distance, and the hub rotates through a second angular distance different from the first angular distance;
the housing includes a housing member defining a gear member axis eccentric to the axis of rotation; and further comprising:
a gear member rotatably disposed in the housing about the gear member axis and operatively associated with the hub and the reel;
wherein, as tape is withdrawn from the reel, the consequent rotation of the reel about the axis of rotation results in eccentric rotation of the hub relative to the housing; and
wherein the hub rotates through an angular distance different from that of the reel.

2. The tape rule assembly claimed in claim 1 , wherein:
the hub includes two annular side walls defining respective bearing surfaces; and
wherein a surface of the reel is rotatably journaled on the hub bearing surfaces.

3. The tape rule assembly claimed in claim 1 , wherein the reel rotates through a greater angular distance than does the hub, and in the same circumferential direction as does the hub.

4. The tape rule assembly claimed in claim 1 , wherein:
the reel and hub are formed of plastic;
the hub annular side walls defining respective bearing surfaces; and
wherein a surface of the reel is rotatably journaled directly on the hub bearing surfaces.

5. The tape rule assembly claimed in claim 1 , wherein:
the housing includes two opposing side walls;
each housing side wall defines an annular support member extending axially inwardly;
the annular support members are axially aligned along the gear member axis;
the hub is concentrically rotatably disposed within the reel about the axis of rotation and includes two side walls, each hub side wall supporting a plurality of annular members extending axially outwardly from respective hub side walls;
the axis of rotation is parallel and eccentric to the gear member axis;
the reel includes two end faces, each reel end face includes a ring defining a plurality of radially-inwardly-directed alternating cycloidal drive teeth and drive recesses;
the gear member defines a central through-bore and is disposed within, and radially aligned with, each reel end face, each gear member rotatably supported on each housing side wall annular support member via respective gear member central through-bores, such that the axes of rotation of the gear members are eccentric relative to the axis of rotation of the hub and reel;
each gear member includes a plurality of radially-outwardly-extending driven teeth, each gear member further defining a plurality of clearance apertures operatively associated with the plurality of hub annular members;
the plurality of driven teeth of each gear member is configured to cooperate with the plurality of alternating cycloidal drive teeth and drive recesses;
the number of the plurality of alternating cycloidal drive teeth and drive recesses of the reel is greater than the number of the plurality of driven teeth of the gear member;
the reel ring is configured to cooperate with the gear member, the housing and the hub so that when the tape is extended from the housing tape exit, the reel cycloidal drive teeth rotatably drive the gear member driven teeth, and the gear member in turn eccentrically rotates the hub via engagement of respective gear member clearance apertures with the hub annular members so that the angular distance traveled by the hub is greater than the angular distance traveled by the reel; and
wherein the gear member clearance apertures are configured to accommodate the eccentric rotation of respective hub annular members relative to the gear member.

6. The tape rule assembly claimed in claim 5 , wherein:
the hub rotates through a greater angular distance than does the reel;
a hub outer surface includes at least one bearing surface; and
wherein an inner surface of the reel is rotatably journaled on the at least one bearing surface.

7. The tape rule assembly claimed in claim 5 , wherein:
each hub annular member includes a roller engageable with the gear member via a respective clearance aperture;
each gear member includes eight equally-circumferentially-spaced driven teeth;
each reel end face defines nine equally-circumferentially-spaced sets of alternating cycloidal drive teeth and recesses; and
wherein, for every eight revolutions of the reel, the hub makes nine revolutions, thereby resulting in one wrap of spring being tightened around the hub for each eight revolutions of the reel.

8. The tape rule assembly claimed in claim 5 , wherein the reel rotates in the same circumferential direction as the hub.

9. A tape rule assembly, comprising:
a housing; and
a cycloidal differential spring-drive system having an eccentric bearing to create an eccentric cycloidal motion rotatably disposed in the housing;
wherein the cycloidal differential spring-drive system includes a reel supporting a length of tape and a hub supporting a coil of spring; and
wherein the reel is operatively associated with the housing and the hub so that when tape is extended from the housing, the reel rotates through a different angular distance than does the hub.

10. A method of minimizing the diameter of a coil of spring disposed around a hub of a tape rule assembly having a housing, comprising:
creating an enclosed space within the housing uninterrupted by a spindle; and
rotatably disposing a cycloidal differential spring-drive system within the enclosed space, such that rotating a reel of the differential spring-drive system through a first angular distance causes the hub of the differential spring-drive system to rotate through a second angular distance different from the first angular distance;
wherein the cycloidal differential spring-drive system has an eccentric bearing to create an eccentric cycloidal motion.

Assignees

• Stanley Black & Decker Inc

Inventors

• Orsini Antony
• Lombardi Keith M
• Eidinger Bruce

Classifications

• G01B3/1005 Primary

  Means for controlling winding or unwinding of tapes · CPC title

• G01B2003/1023

  Winding mechanisms · CPC title

• G01B2003/103

  operated by springs · CPC title

• G01B3/1041

  characterised by casings · CPC title

• B65H2403/481

  Planetary · CPC title