Automatic door closing device

Details Automatic door closing device Automatic door closing device

1989-11-22

1992-02-25

Seidel, Richard K.

Miscellaneous hardware (e.g., bushing, carpet fastener, caster,

Checks and closers

16 51, 16 58, 16 82, E05F 300

Patent

active

050900897

DESCRIPTION:

BRIEF SUMMARY
The invention relates to an automatic door closing device according to the preamble of claim 1. It preferably concerns tooth-wheel drive door closing devices or crank-gear door closing devices in accordance with German Industry Standards (DIN) 18,263. Said door closing devices are used in fire protection doors, smoke protection doors and residential main locking front/back doors. The requisite energy for the automatic closing is, as a rule, stored in a propeller thrust spring. The closing movement is damped by means of hydraulic throttling. In this connection the externally controlled displaceable hydraulic plunger is arranged between radial throttle bores which are interconnected via a bypass valve which connects, respectively, a pressurized space inside the cylinder in front of the plunger to an unpressurized space behind the plunger via a throttle valve.
Among the door closing devices of this kind known in the art, the damping cylinder, which concurrently forms the housing of the door closing device, is of a single-piece construction, either as a pressure diecast enclosure or as a segment of a corresponding extruded hollow section, preferably consisting of a light metal. Fabrication of such cylinders, as regards the reception for the damping plunger, which must be performed to close tolerances, and the required long bypass valves and with respect to the throttle bores, is difficult and demands specialized tooling machines. As a consequence of the high pressures which result, fabrication of the reception for the damping plunger must be performed to very high tolerances. Fabrication difficulties are particularly encountered with the bypass valve which, as a rule, extends parallel to the damping plunger in the single-piece cylinder and which must be precisely connected to the transversely arrayed throttle bores from the outside or from the inside.
German Patent Specification 931,696 has already proposed arranging a tubular line serving as a bypass valve externally on a special damping plunger which functions to damp a door closing device accommodated in a separate housing. Such an externally located bypass line, however, is inconvenient.
German Patent Specification 826,849 discloses a method for joining, through casting, an added piece with an integrally cast bypass line onto the damping cylinder configured as a housing of an automatic door closing device. Tubular sections have also been integrally cast as a cylinder reception in the housing formed as a casting body. Fabrication of such door closing device housings has proven costly and difficult. It requires precise setting up of the tubular sections in the casting mould. The resulting housing itself is relatively voluminous.
German Patent Specification A 1,584,167 discloses a technique whereby a hollow cylinder is concentrically arrayed on the damping cylinder. The ring slot formed functions as a bypass valve for the hydraulic fluid. The relatively large cross-section of the ring slot, however, does not permit adequate throttle control. Fabrication costs are high.
The task of the invention consists in simplifying, from the production engineering standpoint, an automatic door closing device of the kind designated at the outset.
The task of the invention is solved on the basis of a door closing device displaying all the characteristic features of claim 1.
In accordance with the proposal according to the invention, factory-manufactured sections of tubing can be used for the damping cylinders, which sections, as regards plunger reception, have already been sufficiently tooled to close tolerances. By virtue of the formation of the bypass valve between the outside of the tubular damping cylinder and the compactly superimposed covering element, the intricate bores in the damping cylinder heretofore required are eliminated. The covering elements which conform to the external shape of the tubular damping cylinder only necessitate a very slight enlargement of the outside diameter of the cylinder.
According to a preferred embodiment of the invention according to cl

REFERENCES:
patent: 3079629 (1963-03-01), Millard
patent: 3574886 (1971-04-01), Solovizfe
patent: 3584331 (1971-06-01), D'Hooge
patent: 3887961 (1975-06-01), Saajos
patent: 3913170 (1975-10-01), Nakane
patent: 4115897 (1978-09-01), Zunkel
patent: 4601502 (1986-07-01), Van Dyke

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