Buffering device capable of lower-limit position adjustment

A buffering device capable of lower-limit position adjustment, mounted to a roller blind, the buffering device comprising:

• a fixed sleeve mounted around a bar of the roller blind, wherein the bar extends in an axial direction, and the fixed sleeve is not rotatable with respect to the bar;
• at least one constricting spring tightly wound around an outer periphery of the fixed sleeve in the axial direction, wherein the constricting spring has two end portions, and when an external force is applied to push the two end portions toward each other, the constricting spring is elastically loosened and no longer tightly wound around the outer periphery of the fixed sleeve;
• an adjustment ring mounted around an outer periphery of the constricting spring, wherein the adjustment ring is provided with an opening, the opening has two lateral edges each forming a pushing portion, and the two end portions of the constricting spring are located between the two pushing portions such that when the adjustment ring is rotated, one of the pushing portions is subjected to the external force and transfers the external force to, and thereby pushes, a corresponding one of the end portions of the constricting spring;
• a sleeve base mounted around an outer periphery of the adjustment ring, wherein the sleeve base is protrudingly provided with a push block, and the push block extends into the opening of the adjustment ring and is located between the two end portions of the constricting spring such that when any one of the end portions is pushed by the corresponding one of the pushing portions, the push block is pushed by the one of the end portions and rotates the sleeve base;
• and
• a lower-limit position defining base threadedly provided on an inner tube of the roller blind, wherein the lower-limit position defining base is rotatable by the sleeve base via a transmission spring in order to move the inner tube in the axial direction with respect to the lower-limit position defining base.