My invention consist of visual disappearance of the gadget which, once it is inserted inside the door, leaves the external aspect unchanged.
Thanks to ita cylindrical form and the fact that is easy to fit in, it can be fitted in aluminium, ivon and wooden doors.
The hidraulic piston can work following two systems:

1. 1) Double piston system (FIG. 4°)
2. 2) Single piston system with internal spherical valve (FIG. 5)

The pre-exstig techinique of old door-checks consisted of an external arm which pushed the door in order to shut it. The arm ivas scissor-shaped. As a result, its old-fashioned function was different from that of my invention, besides, it had a very inelegant appearance.

A hydraulic built-in door check is known from US-A-3 343 203 comprising the features of the preamble of claim 1.

The purpose of the built-in door check is to close a door automatically when it has been left open by means of the forward and backward sliding of the piston, in the internal starter shaft; by so doing, it opens and blocks the oil passage in order to lubrificate the system. (FIG.4) The fastening of the door is activated by a spring which in turn is regu lated by the piston. (FIG. 2')
On sliding, the piston blocks the oil influx, letting only the necessary amount in order for the door to close slowly.
On fastening, the click, which denotes the definitive fastening of the door, is obtained by widening a part of the cylinder which, given that i it is wider than the diameter, lets the piston slide without any resistance.
The starter shaft consist of 180° arc-shaped arm, a return spring and a hydraulic piston (FIG.1)). All three conponents are inserted in a cilinder. A plate with side holes at the far ends so that, it can be fixed onto the door and a central tunnel. (FIG. 1)
Shapped one, is attached to one of the ends of the cilinder.(
The closing click can be fixed or adjustable, the latter being possible in two ways:

1. 1) by threading the starter shaft, which screws on to one of the ends of the arc-shapped arm leads to the lenthening or shortening of the starter shaft. In this way it carries the piston along with it; the piston is thusshifted to the deired position and brings about the more or less strong click.
2. 2) by tightening the screw positioned on the plate.

FIG.1) -

Illustrates all the details or componente of the door-check.

FIG.2) -

Illustrates a cross-section of the cylinder showing the maximum diameter of the click and point where the piston slides inside the shortest diameter.

FIG.3) - Illustrates the connecting starter shaft of the componentes in

cluding the arm, the click regulation bolt.

FIG. 4) -

Illustrates the starter shaft and the piston and their function inside the cilinder.

FIG. 5) -

Illustrates the dual function of the piston;

FIG. 6) -

Illustrates the click-regulates fixing plate oh the door frame.

FIG. 7) -

Illustrates the definitive positioning of the door-check.

MY INVention named "BUILT-IN DOOR-CHECK", can be used for closing door of all kinds and models

In the industrial field, the built in door-check can be used in banks, shops, offices, dwelling and in any context in which it is necessary to clo close a door automatically without making use of one's hands.