Latch spring mechanism

A latch bolt mechanism for a window sash which is movable with respect to a window frame, said latch bolt mechanism comprising:

• an elongated housing having top, bottom, side and back walls and being open at a front end,
• an integrated, one-piece latch bolt and actuating spring formed of a plastic material received within said housing,
• said latch bolt having front and back ends and spaced apart sides and being of a width to be closely received between the side walls of said housing and slideably guided thereby for movement on a longitudinal axis in said housing over a predetermined distance between a fully extended limit position and a fully retracted limit position,
• said actuating spring being integrally joined, at a front end thereof, with said back end of said latch bolt as a one-piece molding and extending longitudinally rearward from said latch bolt,
• said actuating spring having an extended condition and a compressed condition, when said latch bolt is in said fully extended and fully retracted limit positions, respectively,
• a back end of said actuating spring, when said latch bolt is in said fully extended limit position, extending to said housing back wall to retain said latch bolt in said fully extended limit position,
• said actuating spring comprising a series wave-shaped sections, each formed of alternately reversely oriented U-shaped sections open at one side and having a semi-cylindrical portion at an opposite side,
• each of said semi-cylindrical portions being joined to an adjacent one of said semi-cylindrical portions by an integrally molded connecting section disposed transversely to said longitudinal axis, forming legs of said U-shaped sections, wherein adjacent connecting sections are disposed in substantially parallel relation to each other when said actuating spring is in said extended condition, each of said wave-shaped sections having an amplitude, measured between laterally outermost surfaces of adjacent semi-cylindrical portions, such that, when said actuating spring is in said compressed condition, said wave-shaped sections are laterally confined by the housing side walls,
• said semi-cylindrical portions each having an outside radius which is less than one-third of said amplitude and greater than one-fourth of said amplitude,
• a forwardmost connecting section of said connecting sections is positioned closest to the back end of said latch bolt, being integrally joined with said back end, closely adjacent to one of the side walls of said latch bolt, by an arcuate spring section extending laterally and forwardly from an end of said forwardmost connecting section to space said forwardmost connecting section rearwardly from the back end of said bolt latch,
• a rearwardmost connecting section of said connecting sections is positioned closest to the back wall of said housing, being integrally joined with an arcuately shaped resilient tail section forming the back end of said actuating spring, said resilient tail section extending rearwardly over an arc of about 180° from said rearwardmost connecting section and having a portion positioned for contact with the housing back wall,
• said actuating spring having an extended length when the actuating spring is in said extended condition and a compressed length when the actuating spring is in said compressed condition, wherein said compressed length is less than 60% of said extended length, and a spacing between adjacent ones of said connecting sections, when said actuating spring is in said extended condition, is less than 15% of the extended length.