Patent ID: 8079318
Filing Date: 2011-12-20
Classification: D05B

Abstract:
1. A sewing machine comprising: a needle bar disposed so as to vertically reciprocate with respect to a frame but constantly biased upward, and having an engaging device provided at an upper portion of the needle bar; a positioning block that defines an upper dead point of the needle bar; and a carriage to be driven by a main shaft so as to vertically reciprocate in a direction parallel to the needle bar; the carriage including a latching portion disposed so as to move between an engaging position where the latching portion can be engaged with the engaging device and a retreated position where the latching portion is not engaged with the engaging device; the latching portion being constantly subjected to a biasing force applied in a direction from the retreated position toward the engaging position, so that the latching portion normally remains engaged with the engaging device of the needle bar to cause the needle bar to vertically reciprocate with vertical reciprocating motion of the carriage; the sewing machine also comprising a skipping mechanism including a solenoid with a rotating shaft set to reciprocatively rotate and to be driven in one direction when power is supplied to the solenoid; and an operating member radially spaced from the rotating shaft of the solenoid and connected to the rotating shaft of the solenoid, so as to circumferentially rotate with rotation of the rotating shaft of the solenoid; the operating member being set to be engaged with the latching portion of the carriage when power is supplied to the solenoid thus allowing the latching portion to recede from the engaging position to the retreated position, and to allow the latching portion to return to the engaging position when power to the solenoid is disconnected; wherein an operating member return spring is provided between the operating member and the frame; and the operating member return spring is formed such that, in a process that upon supplying power to the solenoid the latching portion is being driven from the engaging position to the retreated position, a spring force of the operating member return spring is not, or only weakly exerted on the operating member while the latching portion is located between the engaging position and the vicinity of a departing point where the latching portion starts to be disengaged, and that the spring force is relatively strongly exerted on the operating member while the latching portion is located between the vicinity of the departing point and the retreated position, so that resilient force is stored in the operating member return spring with the movement of the operating member.