Background Art As well known to those skilled in the art, a hydraulic floor hinge is used for supporting a door on a support floor while hydraulically absorbing undesirable mechanical impact in the case of opening or closing the door, thus allowing the door to be smoothly operated. A conventional floor hinge comprises a casing fixedly set in a support floor, a hydraulic hinge actuating unit set within the casing, and a top cover covering the top of the casing with a pivot of the hydraulic hinge actuating unit being exposed outside the top cover. The above top cover is firmly locked to the top flange of the casing at several positions using a plurality of set screws. In such a floor hinge, the viscosity of the actuating fluid of the hinge actuating unit is thermally changed in accordance with an atmospheric temperature, and so the pressure of the fluid is changed. Such a thermal-change in the pressure of the fluid also changes the shock absorbing capacity of the floor, thus undesirably changing the moving velocity of a door when the door is opened or closed. Therefore, it is necessary for such a hydraulic floor hinge to be provided with a pressure adjusting screw for allowing a user to appropriately adjust the pressure of the actuating fluid when necessary. In such a conventional hydraulic floor hinge, the pressure adjusting screw is set on a predetermined position on the top portion of the hydraulic hinge actuating unit within the covered casing. When it is necessary to adjust the pressure of the actuating fluid, a user

has to loosen the set screws one by one and remove the top cover from the casing so as to reach the pressure adjusting screw prior to controlling the adjusting screw.

This is very inconvenient to users and makes the users waste time while adjusting the pressure adjusting screw or repairing the hydraulic hinge actuating unit enclosed within the covered casing.

That is, since the set screws, locking the top cover to the top flange of the casing, are always exposed to the outside of the support floor, they may easily rust.

In such a case, it is very difficult to loosen or tighten the set screws. In an effort to overcome the problem caused by the set screws, an opening may be formed on the top cover at a position corresponding to the pressure adjusting screw, thus allowing a user to reach the pressure adjusting screw through the opening.

However, such an opening also allows a variety of external impurities, such as water, sand and dust, to reach the pressure adjusting screw, thus causing a malfunction of the pressure adjusting screw and preventing a user from easily operating the pressure adjusting screw.

Disclosure of the Invention Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a hydraulic floor hinge for doors, which is designed to allow a user to easily and simply reach and operate the pressure adjusting screw for a hydraulic hinge actuating unit when necessary, with the pressure adjusting screw being enclosed within a covered casing to be normally protected from external impurities.

In order to accomplish the above object, the present invention provides a hydraulic floor hinge for doors, comprising an internally-threaded hole formed on the top cover of a casing at a position corresponding to the pressure adjusting screw enclosed within the covered casing, with an annular step formed on the outside surface of the cover along the edge of the internally-threaded hole. A screw cap is normally tightened to the internally-threaded hole at the outside of the

cover so as to close the hole and to protect the pressure adjusting screw from external impurities. The cap movably engages with the internally-threaded hole at its externally-threaded part and is closely seated on the annular step at its slotted head while being exposed to the outside of the cover.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a plan view of a hydraulic floor hinge having a screw cap in accordance with the preferred embodiment of the present invention; Fig. 2 is a sectional view taken along the line A-A of Fig. 1, showing the floor hinge with the cap being removed from the hinge; and Fig. 3 is a sectional view of the floor hinge of Fig. 2.

Best Mode for Carrying Out the Invention Figs. 1 to 3 are views, showing a hydraulic floor hinge having a screw cap in accordance with the preferred embodiment of this invention. As shown in the drawings, the hydraulic floor hinge for doors of this invention comprises a lower casing 10, a hydraulic hinge actuating unit 11 set within the casing 10 and provided with a pressure adjusting screw 13, and a top cover 12 closing the casing 10. The floor hinge further comprises an internally-threaded hole 14, which is formed on the top cover 12 at a position corresponding to the pressure adjusting screw 13 enclosed within the covered casing 10. A screw cap 18 is normally tightened to the internally-threaded hole 14 at the outside of the top cover 12 so as to normally close the hole 14. The head 16 of the screw cap 18 is slotted at its top surface, thus having a slot 15 at which a screwdriver may be utilized to rotate the screw cap 18 when necessary. The above screw cap 18 also has an externally- threaded part 17 and movably engages with the internally-threaded hole 14 at the

externally-threaded part 17.

In the present invention, it is preferable to form an annular step 19 on the outside surface of the top cover 12 along the edge of the internally-threaded hole 14, thus allowing the slotted head 16 of the cap 18 to be closely seated on the annular step 19 while being exposed to the outside of the top cover 12. Due to the annular step 19, the contact area between the head 16 of the screw cap 18 and the top cover 12 is increased as best seen in Fig. 3, thus improving the sealing effect between the cap 18 and the cover 12. Therefore, it is possible to almost completely prevent external impurities from being introduced into the interior of the casing 10 and prevent both the hole 14 and the externally-threaded part 17 of the cap 18 from rusting. This finally prevents a malfunction of the floor hinge and allows a user to easily and conveniently open or close the cap 18 when necessary.

When it is necessary to control the pressure adjusting screw 13 of the hydraulic hinge actuating unit 11, the screw cap 18 is removed from the top cover 12 using a screwdriver (not shown). The screw cap 18 removed from the cover 12 is shown in Fig. 2. After the pressure adjusting screw 13 is appropriately adjusted, the screw cap 18 is retightened to the internally-threaded hole 14 of the cover 12 using the screwdriver. The tightened position of the screw cap 18 on the cover 12 is shown in Fig. 3.

Industrial Applicability As described above, the present invention provides a hydraulic floor hinge for doors. The floor hinge of this invention is designed to allow a user to easily and simply reach and operate the pressure adjusting screw for a hydraulic hinge actuating unit when necessary, with the pressure adjusting screw being enclosed within a covered casing to be normally protected from external impurities. That is, an internally-threaded hole is formed on the top cover of the casing at a position corresponding to the pressure adjusting screw enclosed within the covered casing, while a screw cap is normally tightened to the internally-threaded hole at the

outside of the top cover so as to close the hole. When it is necessary to operate the pressure adjusting screw in order to control the pressure of the actuating fluid of the hydraulic hinge actuating unit in accordance with a variation in an atmospheric temperature changing the viscosity of the actuating fluid, the screw cap is removed from the internally-threaded hole of the top cover by a screwdriver, thus allowing a user to easily reach the pressure adjusting screw without removing the cover from the casing. After appropriately adjusting the pressure of the actuating fluid of the hinge actuating unit by operating the pressure adjusting screw, the cap is retightened to the internally-threaded hole of the cover. The floor hinge of this invention allows a user to easily control the pressure adjusting screw while almost completely preventing an introduction of external impurities into the interior of the casing.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.