Patent GB-1414851-A (GB)
Title: Door check mechanisms
IPC: E05F15/20
Filed: 1973-02-26
Abstract: 1414851 Spring door closers with hydraulic checks REPUBLIC INDUSTRIES INC 26 Feb 1973 [28 July 1972] 9373/73 Heading E2M [Also in Division F2] A spring door closer, in which a piston 22 connected to a door to move within a cylinder 16 compresses a closer spring 38 as the door opens and displaces hydraulic fluid through restricted passages to provide means for checking the door movement, includes a mechanism for holding the door in any opened position comprising: a tubular extension 82 on that end of the cylinder towards which the piston is moved as the door closes, a second piston 88 moving in the extension and biassed by a light spring 124 to follow the movement of the main piston 22, an end plug 114 blocking the extension 82, a one-way valve 104 which allows fluid to pass, via annular cavity 98, into the space between the second piston and the end plug as the door opens, and a fluid passage formed in the end plug which receives fluid displaced from this space and delivers it, via a return sleeve 126, through a passage 90 formed in the second piston; an electrically actuated valve plunger 160 being held against a seat 168 in the passage through the end plug to prevent fluid flow therethrough and stop the door closing. Movement of the door is transmitted by a linkage 17 to a shaft 14 which engages a rack 34 formed in an aperture 24 of the piston. The check mechanism is shown most clearly in Fig. 3: as the door closes the piston 22 moves to the right from the Fig. 1 and Fig. 3 position and displaces hydraulic fluid through duct 68 and tightly restricted valve 72 through a less tightly restricted valve 66, then via passages 64 and 52 into the piston aperture 24 to be discharged through one-way valve 44. Near the end of the closing movement duct 68 is covered by the piston and flow is through valve 72 alone to provide increased damping. When the door opens, the piston moves to the left from the Fig. 2 position and displaces fluid through restricted valve 56 into the piston aperture for discharge through one-way valve 45. During the opening movement of the door, the fluid discharged through valve 45 can move past the valve 104 and through the second piston 88 into the extension 82; but as the door closes and the second piston is moved into the extension the fluid can only discharge through channels 140, 142, 166, 146 and 144 in the end plug of the extension and through sleeve 126 which is in fluid tight sliding engagement in a bore 90 through the second piston. Once through the piston 88 the fluid can be discharged through the valve 72, 66 as described above, but a solenoid 184 can be energised to move an armature 186 to hold a ball valve 164 against valve seat 168-this blocks channel 166 in the end plug and stops fluid movement to hold the door against closure. The construction shown is designed to permit manual overpowering of the solenoid lock mechanism to close the door, but will re-lock when manual pressure is removed. In a further embodiment of this lock mechanism (Figs. 5, 6, not shown) the plunger acting on the valve ball is modified by being designed, once the mechanism has been initially overpowered and fluid is flowing toward the plunger, to present a face to the fluid of sufficient surface area to allow the fluid to hold the plunger back even after manual force has been removed. This modification is the subject of Specification 1414852.