Tape measure with compact retraction system

Patent metadata

Field	Value
Publication number	US-9874428-B1
Application number	US-201715782978-A
Country	US
Kind code	B1
Filing date	Oct 13, 2017
Priority date	Oct 5, 2016
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A tool, such as a tape measure, including a spring-based retraction system is shown. Various spring-based retraction system embodiments are configured to decrease the size occupied by the spring within the tape measure housing, which consequently reduces tape measure housing size providing a more compact tape measure. Various spring-based retraction system embodiments are configured to control retraction of the tape measure in a manner that reduces whip or otherwise controls tape blade retraction. Some retraction system embodiments utilize a reduction gear train, and others utilize a compression spring and a transmission system that converts rotational movement of the tape reel to axial movement, which compresses the spring.

First claim

What is claimed is:

1. A tape measure comprising:
a housing;
a shaft coupled to the housing;
a tape reel rotatably mounted within the housing around the shaft, the tape reel comprising a radially outward facing surface and a radially inward facing surface defining an interior reel cavity;
an elongate tape blade wound around the radially outward facing surface of the tape reel, the elongate tape blade having an upper surface with a concave profile when extended from the housing;
a spiral spring located at least partially within the interior reel cavity and at least partially surrounded by the elongate tape blade in the radial direction, the spiral spring is coupled between the tape reel and the shaft such that when the elongate tape blade is unwound from the tape reel to extend from the housing the spiral spring stores energy and the spiral spring releases energy driving rewinding of the elongate tape blade on to the tape reel;
a reduction gear train rotatably coupling the spiral spring to the tape reel such that, during extension of the elongate tape blade from the housing, each full rotation of the tape reel is translated into less than a full rotation of the spring; and
a hook assembly coupled to an outer end of the elongate tape blade.

2. The tape measure of claim 1 , wherein at least one gear of the reduction gear train is located radially inside of the tape reel such that the at least one gear is at least partially surrounded by the elongate tape blade in the radial direction, wherein the elongate tape blade has an average width, TW, greater than 10 mm.

3. The tape measure of claim 1 , wherein the reduction gear train is a planetary gear train comprising:
a sun gear;
a ring gear surrounding the sun gear; and
a planetary gear located between the sun gear and the ring gear.

4. The tape measure of claim 3 , wherein at least one of the sun gear and the ring gear rotates in a path around the shaft.

5. The tape measure of claim 4 , wherein the planetary gear rotates about an axis at a fixed location relative to the shaft.

6. The tape measure of claim 3 , wherein one of the sun gear and the ring gear is rigidly coupled to the tape reel.

7. The tape measure of claim 6 , wherein an inner end of the spiral spring is coupled to the shaft.

8. The tape measure of claim 7 , wherein the shaft is rotatably coupled to the housing such that the shaft rotates during extension or rewinding of the elongate tape blade.

9. The tape measure of claim 8 , further comprising a spring spool including a radially inward facing surface defining an interior spring spool cavity, wherein the spring spool is located at least partially within the interior reel cavity, and the spiral spring is located within the interior spring spool cavity, wherein an inner end of the spiral spring is coupled to the shaft and an outer end of the spiral spring is coupled to the spring spool.

10. The tape measure of claim 1 , further comprising a total spiral spring length, wherein the elongate tape blade has a length between 6 feet and 50 feet, wherein a ratio of the length of the elongate tape blade to the total spiral spring length is greater than 2.52.

11. The tape measure of claim 10 , wherein the ratio of the length of the elongate tape blade to the total spiral spring length is between 3 and 15.

12. The tape measure of claim 1 , wherein the reduction gear train provides a gear reduction such that a full turn of the spiral spring about the shaft results in at least 1.5 rotations of the tape reel about the shaft.

13. The tape measure of claim 12 , wherein the reduction gear train provides a gear reduction such that a full turn of the spiral spring about the shaft results in between 1.8 and 3.5 rotations of the tape reel about the shaft.

14. The tape measure of claim 1 , wherein the elongate tape blade comprises a metal core and a coating layer, and the metal core has an average thickness, TT, and the spiral spring has an average thickness, ST, wherein TT/ST is less than 0.72.

15. The tape measure of claim 14 , wherein TT/ST is between 0.1 and 0.7.

16. The tape measure of claim 1 , wherein the housing has a maximum outer width dimension of 45 mm to 63 mm, a maximum outer height dimension of 69 mm to 103 mm, and a maximum outer length dimension of 78 mm to 110 mm.

17. The tape measure of claim 1 , wherein there is only one spiral spring located within the interior reel cavity.

18. The tape measure of claim 1 , wherein the tape reel comprises a diameter, D, measured across the radially outward facing surface of the tape reel, wherein the elongate tape blade has a total maximum extended length of TL, wherein TL/D is greater than 165.

19. The tape measure of claim 18 , wherein TL is less than 29 feet.

20. The tape measure of claim 18 , wherein TL is less than 27 feet.

21. The tape measure of claim 18 , wherein TL/D is greater than 195.

22. The tape measure of claim 18 , wherein TL/D is greater than 237.

23. The tape measure of claim 18 , wherein TL/D is greater than 240.

24. The tape measure of claim 18 , wherein TL/D is less than 250.

25. The tape measure of claim 18 , wherein there is only one spiral spring located within interior reel cavity.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Nelson Collin J
• Wortelboer David Andrew
• Anderson Kyle C
• Khangar Abhijeet A
• Vitas Jonathan F

Classifications

• G01B3/1005 Primary

  Means for controlling winding or unwinding of tapes · CPC title

• G01B2003/103

  operated by springs · CPC title

• G01B3/1041

  characterised by casings · CPC title