Door closing mechanism

摘要

The present invention relates to a mechanism for closing a hinged member which comprises a resilient element for effecting closure of the hinged member and a hydraulic damper 5. The hydraulic damper 5, comprising a closed cylinder cavity 20 within a cylinder barrel 19, a rotational damper shaft 22 which extends into the cylinder cavity 20, and a piston 21, placed within the cylinder barrel 19 so as to divide the cylinder cavity 20 into a first side 20a above the piston 21 and a second side 20b below the piston 21. An outer perimeter surface of the piston 21 presents a clearance fit with an inner perimeter surface 27 of the cylinder barrel 19 at 20° C. The cylinder barrel 19 is made of a first material and the piston 21 of a second material which has a higher thermal expansion coefficient than the first material. In this way variations of the viscosity of the hydraulic fluid as a result of pressure fluctuations are compensated for by an increase or a decrease of the cross-section area of the clearance.

主权项

1. A hydraulic damper (5; 60) for closing a hinged member (H) comprising:
a cylinder barrel (19; 68); a closed cylinder cavity (20; 70) formed within the cylinder barrel (19; 68); a piston (21; 72) placed within the closed cylinder cavity (20; 70) so as to divide the closed cylinder cavity (20; 70) into a first side (20a; 70a) and a second side (20b; 70b); and a damper shaft (22; 62) coupled to the piston (21; 72) for dampening closing movement of the hinged member, wherein, at least at 20° C., an outer perimeter surface of the piston (21; 72) defines a clearance between an inner perimeter surface (27) of the cylinder barrel (19) to allow hydraulic fluid contained in the cylinder cavity (20; 70) to flow through the clearance between the outer perimeter surface of the piston (21; 72) and the inner perimeter surface of the cylinder barrel (19) between the first side (20a; 70a) and the second side (20b; 70b) of the closed cylinder cavity (20; 70), wherein the cylinder barrel (19; 68) is made of a first material, having a first thermal expansion coefficient and the piston (21; 72) is made of a second material having a second thermal expansion coefficient, the second thermal expansion coefficient being larger than the first thermal expansion coefficient so that the clearance decreases when the temperature of the damper (5; 60) is raised and increases when the temperature of the damper (5; 60) is lowered, and wherein the difference between the first and second thermal expansion coefficients is at least 1.5×10−5 K−1.