Spring motor for generating constant torque

• US 6,199,664 B1
• Filed: 11/16/1998
• Issued: 03/13/2001
• Est. Priority Date: 11/16/1998
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Tkaczyk, John Eric, Tiemann, Jerome Johnson
• Primary Examiner(s): Bucci, David A.
• Assistant Examiner(s): HANSEN, COLBY M
• Application Number:
  US09/192,464
• Time in Patent Office: 848 Days
• Field of Search: 185/10, 185/39, 185/43, 185/37, 290/1.R
• US Class Current: 185/39
• CPC Class Codes: F03G 1/00 Spring motors spring-driven toys A63H; springs in general F16F; precision time mechanisms, e.g. for clocks or watches, G04B

Abstract

A spring motor for driving an electric power generator with constant power includes a crank-up spool, a take-up spool, and a relatively wide, flat tape spring which winds in a relaxed condition on the take-up spool. In one form, the spring has a width which varies approximately linearly from one end to another end so as to generate a constant torque at a fixed radius from an axis of the crank-up spool as the spring unwinds. In another form, the spring width is constant and a separate drum is driven by contact with the unwinding spring, with the separate drum driving an output shaft. In still another form, an idler wheel is driven by contact with the spring and the output shaft is driven from the idler wheel through gear contact with the periphery of an output drum mounted on the output shaft.

Claims

1. A spring motor for delivering constant power to a load, the spring motor comprising:

a crank-up spool and a take-up spool;

a flat, tape spring pre-treated to wind normally in a relaxed configuration about said take-up spool;

means for winding said spring in a reverse, tensioned configuration on said crank-up spool with at least one end of said spring being attached to said take-up spool, whereby release of said winding means allows said spring to unwind from said crank-up spool and rewind onto said take-up spool;

an idler shaft coupled in driven relationship to said spring whereby transfer of said spring from said crank-up spool to said take-up spool causes rotation of said idler shaft;

an idler wheel attached to said idler shaft and positioned in frictional engagement with said spring; and

a plurality of uniformly spaced notches in said spring, said idler wheel including means for engaging said notches to establish a positive driving relationship between said spring and said shaft.

2. The spring motor of claim 1 wherein the width of the spring is defined by:

3. The spring motor of claim 2 and including an electric power generator coupled to be driven by rotation of said crank-up spool.

4. The spring motor of claim 1 wherein said means for engaging said notches comprises a plurality of teeth uniformly circumscribing said idler wheel.

5. The spring motor of claim 4 and including:

an output shaft;

an output spool mounted on said output shaft; and

means drivably coupling said idler shaft to said output spool.

6. The spring motor of claim 1 wherein said spring is formed with a width which varies generally linearly from a narrow width at said at least one end to a wider width at the opposite end thereof such that torque generated by said spring remains constant with change in radial displacement of said spring on said crank-up spool.

7. The spring motor of claim 6 and including;

an electric power generator having a rotor shaft; and

a gear train for coupling said output shaft to said rotor shaft for establishing a desired torque at the rotor shaft.