Coil spring
Patent 4957278 Issued on September 18, 1990. Estimated Expiration Date: 
April 12, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
April 12, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesWire for coiled spring Patent #: 4735403 InventorsAssigneeApplicationNo. 336476 filed on 04/12/1989US Classes:267/166, COIL267/180IrregularExaminersPrimary: Reger, Duane A.Attorney, Agent or FirmForeign Patent References
International ClassF16F 001/10Foreign Application Priority Data1989-01-10 JPAbstractA coil spring has a strand having a width w and a thickness t, such that 1.1ࣘcࣘ1.7, where c is a ratio determined according to c=w/t. Further, the strand has a cross-sectional shape defined by a plurality of partial curves, which are portions of a clothoid, a curve whose radius varies inversely in proportion to its length. Further, the partial curves are combined to form a closed loop. The tangent lines of any adjacent two of the partial curves of the coil spring, at their boundaries where they are combined, are oriented in the same direction. | |
