WO2007013776A1

WO2007013776A1 - Hinge apparatus having automatic return function

Info

Publication number: WO2007013776A1
Application number: PCT/KR2006/002975
Authority: WO
Inventors: Soon Woo Choi
Original assignee: I-One Innotech Co., Ltd.
Priority date: 2005-07-29
Filing date: 2006-07-28
Publication date: 2007-02-01
Also published as: KR20070014713A; KR100835730B1

Abstract

Provided is an automatic return hinge apparatus which includes a torsion spring to reinforce a door closing force and a clutch unit to minimize a door opening force, the torsion spring and the clutch unit being installed in the upper side thereof, and at least one oil-hydraulic circuit installed in the lower side thereof for controlling a restoring force by a return spring, thereby minimizing the diameter of the hinge apparatus. The hinge apparatus includes a first oil-hydraulic circuit providing a uniform damping power, and a second oil-hydraulic circuit which can variably control the damping power according to the ascending position of a piston. Moreover, the hinge apparatus can provide a restoring force for an actuator with only a clutch unit and a torsion spring. The hinge ap paratus emp loys a clutch unit connected with a to rsion sp ring and an oil-hydraulic circuit, which are separately manufactured from each other.

Description

[DESCRIPTION] [Invention Title]

HINGE APPARATUS HAVING AUTOMATIC RETURN FUNCTION [Technical Field] The present invention relates to a hinge apparatus having an automatic return function, and more particularly, to a slim hinge apparatus having an automatic return function for use in a heavy door, which includes a clutch unit which has a torsion spring installed in the upper side of a hinge in order to reinforce a door closing force and minimize a door opening force, and a hydraulic circuit having a return spring which is installed in the lower side of the hinge, to thereby maximize the door closing force while minimizing the diameter of the hinge apparatus, and which further includes a piston unit having a built-in check valve, in which the length of the hinge is extended so that a decrease in a damping force caused by reduction in the diameter of a chamber can be compensated, to thereby increase a damping force according to an addition of another hydraulic circuit.

[Background Art]

A hinge apparatus makes two members spaced from each other or folded one member over another around a shaft, according to necessity. A representative example of the hinge apparatus is a left/right rotational hinge apparatus including a horizontal actuator which is used for a door or window frame, or an up /down rotational hinge apparatus including a vertical actuator which is used for a refrigerator, a mobile phone, or a notebook computer. A conventional hinge apparatus having an automatic return function is disclosed in Korean Laid-open Patent Publication No. 2001-0027832.

In the case of the conventional hinge apparatus, a conversion head ascends according to rotation of a movable hinge plate when a door is opened, and descends according to an elastic restoring force of a compressed spring when the door is closed. In addition, the conventional hinge apparatus controls the amount of the pressurized oil which flows through and an oil circulation path and first and second rate control oil paths and varies an ascending/descending speed of the conversion head to thereby control the closing speed of the door. However, in the case of the conventional hinge apparatus, the conversion head which ascends and descends according to rotation of a door is guided by a pair of guide pins. The guide pins are fixed to hinge knuckles. Also, a cylinder and the conversion head are incorporated in the knuckles of four or so. Accordingly, when the movable hinge knuckles receive big load and rotate for a long time, durability of the hinge apparatus is lowered and the structure is complicated. As a result, an assembly productivity deteriorates.

Also, the inner portion of the conventional hinge apparatus and a mechanism of connecting the fixed portion and the movable portion of the conventional hinge apparatus are applied only in hinge door opening and closing apparatuses. As a result, it is not possible to apply the conventional hinge apparatus to a structure that the center of a door differs from that of the hinge apparatus. Also, a fixing unit for temporarily fixing the door so that the door does not rotate at the state where the door has been opened at a predetermined angle is not installed in the conventional hinge apparatus. Accordingly, it is inconvenient for users to use the conventional hinge apparatus.

Meanwhile, Korean Utility Model Registration No. 0271646 discloses a hinge door opening and closing apparatus in which a hydraulic door closer and a spring door closer are separately configured and the former and the latter are combined with each other.

Meanwhile, the conventional art has not provided an optimized structure of a left/right or up/down rotational door hinge apparatus which is applied in a Kimchi refrigerator for use in a storage unit for storing a fermentation food such as Kimchi which is one of Korean traditional foods, a general refrigerator, a vehicle trunk, and so on.

Also, Korean Patent No. 435188 discloses a hinge apparatus using a single camshaft having a spiral cam diagram whose multi-stage automatic return speed establishment structure is stabilized. However, it is difficult to embed the conventional hinge apparatus into a door since an outer case is needed outwards and thus the total diameter is formed larger than the thickness of the door. If a camshaft and a chamber are reduced in diameter so that the conventional hinge apparatus can be embedded into and used for a door, a sufficient damping force required for closing a door cannot be obtained from the hinge apparatus. As a result, the damping force is reduced and accordingly an automatic return of the door is not accomplished. That is, a door closing speed is not safely controlled at the time of an abrupt door return.

Further, in the case of a hinge apparatus employing a double camshaft which has been proposed by the same applicant as the present invention in Korean

Laid-open Patent Publication No. 2006-18461 on March 2, 2006 (corresponding to Korean Patent Application No. 2004-66832 on August 24, 2004), an upper camshaft which is installed in order to compensate for reduction of a door closing force includes a pair of spiral ascending/descending holes. The spiral ascending/descending holes may cause the rotational force to vary in the vertical direction when a piston rod and a valve are operated by the rotating camshaft, to accordingly cause a loss of 30% or so. As a result, the upper camshaft does not play a big role of improving the door closing force. [Disclosure]

[Technical Problem]

To solve the above problems, it is an object of the present invention to provide a hinge apparatus having an automatic return function for use in a heavy door, which includes a clutch unit which is connected with a torsion spring installed in the upper side of a hinge in order to reinforce a door closing force and a hydraulic circuit having a return spring which is installed in the lower side of the hinge, to thereby maximize the door closing force while minimizing the diameter of the hinge apparatus, and minimize a door opening force at a certain angle or more.

It is another object of the present invention to provide a slim hinge apparatus having an automatic return function which can be buried in a door and further includes at least one hydraulic circuit in the lengthy direction, in order to compensate for a reduction in a damping force which occurs due to a reduction in diameter of a chamber, to thereby increase a closing force of the door. It is still another object of the present invention to provide a slim hinge apparatus having an automatic return function for use in a heavy door, which can be varied in the door and includes a first hydraulic circuit including a notch portion providing uniform damping power for a check valve at a door closing time in order to compensate for reduction in the damping power according to reduction in the diameter of a chamber, and a second hydraulic circuit in which a fluid pressure control rod is inserted into a oil path formed in a piston rod in order to variably control an amount of oil flow, that is, the ascending speed of a piston according to the ascending position of the piston, to thereby increase the damping power. It is yet another object of the present invention to provide a hinge apparatus having an automatic return function for use in a heavy door, which includes an oil-hydraulic circuit playing a role of a damping unit including a notch portion providing uniform damping power for a check valve at a door closing time in order to set a door closing speed at a certain speed. It is yet still another object of the present invention to provide a slim hinge apparatus having an automatic return function for use in a light door, which provides a restoring force for an actuator and an efficient door closing force with only a clutch unit from which a return spring has been removed and which is connected to a torsion spring. It is a further object of the present invention to provide a slim hinge apparatus having an automatic return function for use in a light door, which can be applicable in a structure which can be embedded at both sides of the door and forming a hinge shaft, in which a clutch unit connected with a torsion spring is separately manufactured from an oil-hydraulic circuit which variably can control an amount of oil flow, that is, the ascending speed of a piston according to the ascending position of the piston, while including a built-in return spring.

It is another further object of the present invention to provide a hinge apparatus having an automatic return function including an overpressure prevention valve preventing damage of all kinds of 0-rings for air-tightness between a body and a piston unit from occurring due to overpressure generated in an upper chamber when the door is rapidly closed by an external force such as strong wind. It is still another further object of the present invention to provide a hinge apparatus ha ving an automatic return function which can maintain an opening status of the door in a certain angular interval by appropriately setting up a cam diagram for first and second elevating guide holes of a camshaft.

It is yet still another further object of the present invention to provide a hinge apparatus having an automatic return function which can control a door closing speed at a multi-stage by combination of the shape of a fluid pressure control rod, a cam diagram for first and second elevating guide holes of a camshaft, and a clutch unit which is connected to a torsion spring. [Technical Solution] To accomplish the above object of the present invention, according to an aspect of the present invention, there is provided a hinge apparatus having an automatic return function for a door which has first and second hinges which are fixed to the door and a door frame, respectively, the automatic return hinge apparatus comprising: an upper body on a circumferential surface of which the upper side of the first hinge is integrally formed and whose upper end portion is blocked by an upper cap on the inner side surface of which a recess is formed; a lower body on a circumferential surface of which the lower side of the first hinge is integrally formed and whose lower end portion is blocked by a lower cap which is connected in a sealing manner; a central body on a circumferential surface of which one side of the second hinge is integrally formed and which is pivotally arranged between the upper and lower bodies; a shaft whose lower end portion is rotatably installed in the middle portion of the central body and whose upper end portion is inserted into the recess of the upper cap and is fixed to the upper body; a piston whose outer circumference is slidably installed along the inner circumferential surface of the central body and which divides the inner portion of the central body into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the piston when the rotational force of the door is applied in the shaft according to the rotation of the door; damping means which provides a damping function in order to delay the ascending speed of the piston in the case that the piston ascends according to closing of the door; and return means which provides a restoring force to the rotational/linear motion converter in order to return the door to an initial position at the time when the door is closed.

Preferably, the rotational/linear motion converting means comprises : a guide hole forming portion which has first and second vertical guide holes which are installed in the inner circumferential surface of the central body and face each other in the vertical direction; a camshaft which includes a cylindrical portion in which first and second elevating guide holes which are extended from the shaft and are made of a spiral shape of a movement symmetrical structure for each other along the outer circumferential surface thereof, are penetratively formed and which is pivoted by a relative external force which is applied to the upper body when the door is rotated; and a guide pin whose both end portions are combined with the first and second vertical guide holes via the first and second elevating guide holes, respectively, in which one end of the guide pin is connected to the upper portion of the piston rod. According to another aspect of the present invention, there is also provided a hinge apparatus having an automatic return function for a door which has first and second hinges which are respectively fixed to the door and a door frame, the automatic return hinge apparatus comprising: an upper body on a circumferential surface of which the upper side of the first hinge is integrally formed and whose upper end portion is blocked by an upper cap on the inner side surface of which a recess is formed; a lower body on a circumferential surface of which the lower side of the first hinge is integrally formed and whose lower end portion is blocked by a lower cap which is connected in a sealing manner; a central body on a circumferential surface of which one side of the second hinge is integrally formed and which is pivo tally arranged between the upper and lower bodies,' a shaft whose lower end portion is rotatably installed in the middle portion of the central body and whose upper end portion is inserted into the recess of the upper cap and is fixed to the upper body; an isolation unit for dividing the chamber where the oil is filled in the central body into first and second chambers! first and second pistons whose outer circumferences are slidably installed along the inner circumferential surface of the first and second chambers in the central body and which divides the inner portions of the first and second chambers into upper and lower chambers, respectively; rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the first and second pistons when the rotational force of the door is applied in the shaft according to the rotation of the door; first and second damping means which provide a damping function in order to delay the ascending speeds of the first and second pistons in the case that the first and second pistons ascend according to closing of the door; and return means which provides a restoring force to the rotational/linear motion converter in order to return the door to an initial position at the time when the door is closed.

According to still another aspect of the present invention, there is also provided a hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising: an upper body on a circumferential surface of which the upper side of a first hinge which is fixed to a door is integrally formed and whose upper end portion is blocked by an upper cap; a lower body on a circumferential surface of which the lower side of the first hinge is integrally formed and whose lower end portion is blocked by a lower cap which is connected in a sealing manner; a central body on a circumferential surface of which one side of a second hinge which is fixed to a door frame is integrally formed and which is pivotally arranged between the upper and lower bodies, in which a sealing cap is combined in the lower end portion of the central body; a shaft whose one end is fixed to the upper cap and whose other end is extended to the central body; a piston whose outer circumference is slidably installed along the inner circumferential surface of the central body and which divides the inner portion of the central body into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the piston when the rotational force of the door is applied in the shaft according to the opening and closing of the door; damping means which is installed in the piston, for controlling the descending and ascending speeds of the piston according to the operation of the opening and closing of the door and selectively providing a damping function in the case that the piston ascends; a return spring which is installed in the lower chamber, and is compressed at the opening time of the door and provides a restoring force for ascending the piston at the closing time of the door; a torsion spring which is built in the upper portion of the central body so that one end of the torsion spring is fixed to the upper end portion of the shaft thereby providing a restoring force rotating the shaft in the direction closing the door; and a clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is within the range of the predetermined opening angle.

According to yet an other asp ect of th e present invention, there is also provided a hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising: a body formed of a single cylindrical shape and whose upper end portion is blocked by an upper cap and whose lower end portion is blocked by a lower cap which is connected in a sealing manner; a shaft whose one end is extended to the outside via the upper cap, and whose other end is extended to the body; a piston whose outer circumference is slidably installed along the inner circumferential surface of the body and which divides the inner portion of the body into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the piston when the rotational force of the door is applied in the shaft according to the opening and closing of the door; damping means which is installed in the piston, for controlling the ascending speeds of the piston at the closing of the door", a return spring which is installed in the lower chamber, and is compressed at the opening time of the door and provides a restoring force for ascending the piston at the closing time of the door; a torsion spring which is built in the upper portion of the body so that one end of the torsion spring is fixed to the upper cap, thereby providing a restoring force rotating the shaft in the direction closing the door; and a clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is in the range of the predetermined opening angle.

According to yet still another aspect of the present invention, there is also provided a hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising: first and second hinge apparatus units which are embedded in the lower and upper portions of a door, respectively, wherein the first h inge ap paratus unit comp rises: a first body wh ose up per and lower e nd portions are blocked by first up per and lower cap s, resp ectively; a first sh aft whose one end is extended to the outside via the first upper cap and whose other end is extended to the inner portion of the first body! a torsion spring which is built in the upper portion of the body so that one end of the torsion spring is fixed to the first upper cap, thereby providing a restoring force rotating the first shaft in the direction closing the door; and a clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is within the range of the predetermined opening angle, and wherein the second hinge apparatus unit comprises-' a second body whose upper and portion is blocked by a second upper cap, and whose lower end portion is blocked by a second lower cap in a sealing manner; a second shaft whose one end is extended to the outside via the second upper cap and whose other end is extended to the inner portion of the second body; an isolation unit which divides the chamber of the second body into first and second chambers; first and second pistons whose outer circumferences are slidably installed along the inner circumferential surfaces of the first and second chambers in the second body and which divide the inner portions of the first and second chambers into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the second shaft into axial linear motions of the first and second pistons when the rotational force of the door is applied in the second shaft according to the rotation of the door; and first and second damping means which provide damping functions so that the ascending speeds of the first and second pistons can be delayed in the case that the first and second pistons ascend at the closing time of the door.

According to a further aspect of the present invention, there is also provided a hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising-" first and second hinge apparatus units which are embedded in the lower and upper portions of a door, respectively, wherein the first h inge ap paratus unit comp rises •" a first body wh ose up per and lower e nd portions are blocked by first up per and lower cap s, resp ectively; a first sh aft whose one end is extended to the outside via the first upper cap and whose other end is extended to the inner portion of the first body; a torsion spring whose one end is fixed to the first lower cap, thereby providing a restoring force rotating the first shaft in the direction closing the door; and a ball-type clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is within the range of the predetermined opening angle, and wherein the second hinge apparatus unit comprises: a second body whose upper and portion is blocked by a second upper cap, and whose lower end portion is blocked by a second lower cap in a sealing manner; a second shaft whose one end is extended to the outside via the second upper cap and whose other end is extended to the inner portion of the second body; an isolation unit which divides the chamber of the second body into first and second chambers; first and second pistons whose outer circumferences are slidably installed along the inner circumferential surfaces of the first and second chambers in the second body and which divide the inner portions of the first and second chambers into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the second shaft into axial linear motions of the first and second pistons when the rotational force of the door is applied in the second shaft according to the rotation of the door; and first and second damping means which provide damping functions so that the ascending speeds of the first and second pistons can be delayed in the case that the first and second pistons ascend at the closing time of the door. [Advantageous Effects]

As described above, the present invention provides an automatic return hinge apparatus in which a return spring and a torsion spring are installed together in order to compensate for loss of a closing force in a door which occurs at the automatic opening and returning time of the door, and simultaneously reduce an opening force of the door by a clutch unit so that a heavy door of a large size can be easily opened with a less power.

Additionally, the hinge apparatus of the present invention has the advantage that it is formed into a slim type in order to be embedded in the inner side of all kinds of doors wh ich req uire ultra-typ e s mall di ameter, to th ereby maintain the overall external appearance to be simple, and that it can be applied to heavy and light doors of large and small sizes, respectively, by extending at least one oil-hydraulic circuit, that is, a damping unit in order to prevent degradation of a damping power according to reduction in the diameter. [Description of Drawings]

The above and/or other objects and/or advantages of the present invention will become more apparent by describing the preferred embodiments thereof in detail with reference to the accompanying drawings in which: FIG. 1 is a cross-sectional view showing an automatic return hinge apparatus for a heavy door of a large size according to a first preferred embodiment of the present invention;

FIG. 2 is a perspective view showing a camshaft of the automatic return hinge apparatus shown in FIG. 1 ; FIG. 3 is a schematic diagram showing the location of a guide pin and the compression state o f a return sp ring ac cording to a door opening angle in an elevating guide hole of the camshaft shown in FIG. 2^',

FIG. 4 is a perspective view showing an outer clutch of the automatic return hinge apparatus shown in FIG. 1; FIG. 5 is a partially enlarged sectional view which shows the hydraulic flow at the operation time of an overpressure prevention valve shown in FIG. 1 ;

FIGS. 6A through 6D are top sectional diagrams which sequentially show the operating state of a clutch unit according to the opening of a door, respectively;

FIGS. 7A through 7C are partially enlarged sectional views which sequentially show the hydraulic flow when an actuator descends according to the opening of a do or a ccording to t he first p referred embodiment of th e p resent invention, respectively;

FIGS. 7D and 7E are partially enlarged sectional views which sequentially show the hydraulic flow when the actuator ascends according to the closing of the door according to the first preferred embodiment of the present invention, respectively; FIG. 8 is a partially enlarged sectional view showing the characteristic portion of the automatic return hinge apparatus having the structure that a check valve is embedded in a piston according to a second embodiment of the present invention;

FIG. 9A is a cross-sectional view which shows an automatic return hinge apparatus showing a variation of the first preferred embodiment of the present invention;

FIG. 9B is a cross-sectional view which shows a check valve having a notch portion applied to the variation of the first preferred embodiment shown in FIG. 9A; FIG. 10 is a lengthy direction cross-sectional view showing a slim type automatic return hinge apparatus having a double oil-hydraulic circuit according to a third preferred embodiment of the present invention!

FIGS. HA through HC are partially enlarged sectional views which sequentially show the hydraulic flow when an actuator descends at the opening time of a door according to the third preferred embodiment of the present invention;

FIGS. HD and HE are partially enlarged sectional views which sequentially shows the hydraulic flow when the actuator ascends according to the closing of the door;

FIG. 12 is a lengthy direction cross-sectional view showing a slim type automatic return hinge apparatus having a ball type clutch unit and a double oil-hydraulic circuit according to a fourth preferred embodiment of the present invention;

FIG. 13 is a perspective view showing the ball type clutch unit according to the present invention;

FIGS. 14A through 14C are top sectional diagrams which sequentially show the operating state of the ball type clutch unit at the door opening time," FIG. 15 is a cross-sectional view showing an isolation structure of the slim type automatic return hinge apparatus according to the fourth embodiment of the present invention,"

FIG. 16 is an illustrative view which illustrates the state where the separable automatic return hinge apparatus shown in FIG. 15 has been applied to a door," and

FIG. 17 is an illustrative view which illustrates the state where the integrated automatic return hinge apparatus shown in FIG. 12 has been applied to a door. [Best Mode]

Hereinbelow, an automatic return hinge apparatus according to preferred embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals denote like elements through the following embodiments.

1. First preferred embodiment

1 - 1. Overall structure of hinge apparatus Firstly, referring to FIGS. 1 through 5, an automatic return hinge apparatus according to a first preferred embodiment of the present invention includes an upper body 11, a central body 15 and a lower body 13 which are aligned in the same axial direction along the longitudinal direction. The upper and lower bodies 11 and 13 are combined with the upper and lower sides of a first hinge 21 fixed to a door, respectively. The central body 15 is combined with one side of a second hinge 23 fixed to a door frame.

It has been described that the first and second hinges 21 and 23 are fixed to a door and a door frame, respectively in the first embodiment of the present invention. However, it is not limited thereto in use but it is possible that one of the first and second hinges 21 and 23 is coupled with the door frame and the other is fixed to the door.

Moreover, an upper cap 31 and a lower cap 33 are coupled with the upper side of the upper body 11 and the lower side of the lower body 13, respectively, in order to close the inner portion of the hinge apparatus. A camshaft 50 is inserted into the inner side of the upper body 11 and the central body 15 as shown in FIG. 1.

Moreover, the camshaft 50 is fixed by a pair of fixing pieces 32 in which the upper side of a shaft 51 penetrates the upper body 11 and the upper cap 31. As a result, the camshaft 50 receives the rotational force of the door at the opening and closing time of the door, and thus can rotate in the same rotational direction as that of the door. That is, the leading ends of a pair of the fixing pieces 32 are inserted into joint grooves 52a formed in the upper side of the shaft 51, respectively, and the camshaft 50 is fixed so as to rotate with the rotation of the upper body 11. Furthermore, a cylindrical body 53 extended and formed in the lower end of the shaft 51 has a space portion into which the upper end of a piston rod 61 of an actuator 60 which will be described later is slidably inserted. In addition, the cylindrical body 53 includes first and second elevating guide holes 54a and 54b which are made of a spiral shape of a movement symmetrical structure for each other along the outer circumferential surface thereof. The first and second elevating guide holes 54a and 54b have the cam diagram angles as illustrated in FIG. 3. The cam diagram will be concretely described below with the operation of the hinge apparatus.

In the meantime, in the case of an actuator 60 shown in FIG. 1, the upper portion of the piston rod 61 is penetrated with a guide pin 70. Both ends of the guide pin 70 are penetrated in order to be guided with the first and second elevating guide holes 54a and 54b in the cylindrical body 53.

Furthermore, a piston unit 62 having the diameter contacting the outer circumference of the central body 15 and simultaneously dividing an oil chamber in the central body 15 into upper and lower chambers 91 and 93 is integrally formed in the lower center of the piston rod 61. An overpressure prevention unit 63 forming an overpressure prevention valve 630 is disposed in the lower side of the piston unit 62 at the state where the center of the overpressure prevention unit 63 is penetratively coupled with the lower portion of the piston rod 61.

In this case, a first oil path 68a is formed in the piston rod 61 from the bottom of the piston rod 61 to the top thereof. A second oil path 68b communicating with the upper end of the first oil path 68a and the outer circumference of the piston rod 61 is formed in the piston rod 61. Moreover, the piston unit 62 includes a plurality of third oil paths 68c which are penetrated in the vertical direction.

In the meantime, as shown in FIG. 5, the overpressure prevention valve 630 includes the overpressure prevention unit 63 which is formed a little smaller than the inner diameter of the central body 15. Consequently, a sixth oil path 68f in which the oil in the upper chamber 91 flows into the lower chamber 93 is formed between the external diameter of the overpressure prevention unit 63 and the central body 15.

Moreover, a dish-shaped spring 64 and a snap ring 65 for fixing the dish-shaped spring 64 are sequentially penetratively coupled with the lower end of the piston rod 61 in the lower side of the overpressure prevention unit 63.

The overpressure prevention valve 630 of the above-described structure does not operate in the case that a user closes a door at a normal speed, but operates only in the case that an external force of a big power like the strong wind is applied to a door, and thus the door is rapidly closed. That is, as will be described later, when a door is opened and closed at a normal speed, at least one pair of check valves 631 which are formed according to action of opening and closing balls 63a embedded in the overpressure prevention unit 63 act to block the oil path (see FIG. 7D).

The dish-shaped spring 64 elastically supports the overpressure prevention unit 63 in the lower end of the piston unit 62 with a predetermined pressure. In the case that the overpressure generated in the upper chamber 91 is greater th an th e ela stic force of th e dish -shaped sp ring 64, th e overp ressure prevention unit 63 moves downwards by the pressure of the oil. If the overpressure prevention unit 63 moves downwards, the fifth oil path 68e is formed between the lower surface of the piston unit 62 and the upper surface of the overpressure prevention unit 63. A massive amount of the oil in the upper chamber 91 flows to the lower chamber 93 through the fifth and sixth oil paths 68e and 68f to thus release the overpressure state. Consequently, one of all kinds of O-rings 81-83, 87, and 88 arranged in the neighbor of the central body 15 and the piston unit 62 for maintaining of the air tightness is destroyed or the body is damaged by the overpressure of the upper chamber 91. Accordingly, an oil leaking problem can be prevented in advance.

However, in the case that the pressure generated in the upper chamber 91 becomes smaller than the elastic force of the dish-shaped spring 64, according to the normal closing of the door, the overpressure prevention unit 63 does not move downwards by the pressure of the oil. In this way, if the overpressure prevention unit 63 does not move downwards and maintains the state having contacted the lower surface of the piston unit 62, the fifth oil path 68e is not formed between the lower surface of the piston unit 62 and the upper surface of the overpressure prevention unit 63. Moreover, when the door is opened, the oil moves from the lower chamber 93 to the upper chamber 91 via the fourth oil path 68d and the check valve 631.

In this case, it is preferable that the dish-shaped spring 64 is designed in order to have an elastic coefficient of the extent that the overpressure prevention unit 63 can be moved at the time of generating the overpressure.

In the meantime, a support nut 66 is screw-coupled in the end of the piston rod 61. The support nut 66 plays a role of making the elastic force of the return spring 67 for elastically supporting the actuator 60 not directly affect the elastic force of the dish-shaped spring 64 to thereby smoothly perform the overpressure protection function in the chamber.

In the first preferred embodiment shown in FIG. 1, the check valve 631 has been implemented in the form that the check valve 631 has been separated from the piston unit 62 for the employment of the overpressure prevention valve 630 and built in the overpressure prevention unit 63. However, the employment of the overpressure prevention valve 630 is not essential. That is, in the case that the overpressure prevention valve 630 is not employed, the check valve 631 can be embedded in a built-in structure to replace the third oil path 68c formed in the piston unit 62. An example in which the check valve is integrally formed in the piston unit is shown in FIG. 8 as a second embodiment of the present invention.

Whether or not the overpressure prevention valve is employed and the installation place of the check valve can be identically applied to another preferred embodiment which will be described later. Moreover, the lower end of the return spring 67 is disposed in the lower end of the central body 15 and is combined with a sealing cap 47 for sealing the lower chamber 93. In addition, a ball bearing 48 is installed between the lower cap 33 and the sealing cap 47, and thus it is possible to make a smooth rotation between the central body 15 and the lower body 13. Moreover, a fluid pressure control rod 45 whose leading end is inserted is installed in the first oil path 68a of the piston rod 61, in order to control the inflow of the oil. The lower end of the fluid pressure control rod 45 is fixed by a support 43 installed in the lower cap 33. The specific structure of the fluid pressure control rod 45 will be described later. In addition, an adjusting bolt 41 perpendicularly combined in the center of the lower cap 33 is combined in the inner side of the support 43. Accordingly, the level of the fluid pressure control rod 45 can be set according to the forward rotation/reverse rotation of the adjusting bolt 41, to thus freely set the oil amount which passes through the first oil path 68a. Consequently, the automatic return speed of the door is determined.

1-2. Clutch unit

In the meantime, a torsion spring 76 is arranged at the state of surrounding the shaft 51, in the upper side of the inner portion of the central body 15 for improvement of the closing force at the closing time of a door, and a clutch unit 700 is arranged so as to be connected with the torsion spring 76 in the lower end of the torsion spring 76 in order to control the elastic force generated in the torsion spring 76 according to the rotation of the door.

The clutch unit 700 includes: an outer clutch 71 which is fixed at the inner center of the central body 15 by a fixing piece 72; an inner clutch 73 whose lower end is rotatably inserted into the upper end of the outer clutch 71, and in the internal space of which the shaft 51 in the camshaft 50 is supported at a rotatable contact state; and a pair of roller pins 75 which are disposed between the outer and inner clutches 71 and 73 and play the role of combining the inner clutch 73 with the shaft 51 or separating the former from the latter according to the opening angle of the shaft 51, that is, the door.

Moreover, the torsion spring 76 is fixed with a first fixing hole 77a whose upper end is formed in the lower end of the upper cap 31, and a second fixing hole 77b whose lower end is formed in the upper portion of the inner clutch 73, respectively. Therefore, if the camshaft 50 rotates at the door opening time, the inner clutch 73 operates and rotates, for example, within the range of 0-90°, and accordingly the torsion spring 76 gets twisted to thus cause deformation. Thereafter, in the case that the clutch unit 700 reaches 90° which is a clutching starting angle of the clutch unit 700, a clutching operation is performed and thus the twist deformation of the torsion spring 76 is stopped to then make only the camshaft 50 rotate. The clutch unit 700 shown in the FIGS. 6 A through 6D shows an example of the case where the clutching starting angle is 90°, which is applied to a slim type automatic return hinge apparatus which is suitable for a miniature door which does not use a return spring but uses only a torsion spring. Therefore, in the case of an automatic return hinge apparatus for a heavy door of a large size, which requires for both the return spring 67 and the torsion spring 76, it is possible to establish the clutching starting angle of the clutch unit 700 into a desired angle. For example, the clutching starting angle of the clutch unit 700 can be established to 30°. in the case of setting the clutching starting angle as 30° as described above, a second insertion hole 74c formed in the upper end of the outer clutch 71 based on the time when the camshaft 50 is at the initial state, is arranged in a location which is obtained by making a first insertion hole 74a formed in the outer circumference of the shaft 51 and a throughhole 74b formed in the inner clutch 73 rotate by 30°.

In the meantime, the pair of the roller pins 75 are of a pin-shaped configuration whose cross-section is circular. The pair of the roller pins 75 are inserted so as to move between a pair of first insertion holes 74 which are correspondingly formed on the outer circumference of the shaft 51 and whose cross-section is hemispherical, a throughhole 74b formed in the inner clutch 73, and a second insertion hole 74c formed in the upper end of the outer clutch 71 as shown in FIG. 4 and whose cross -section is hemispherical. The process of being clutched through the pair of the roller pins 75 will be described in detail with the operation of the hinge apparatus which will be described later.

In the meantime, the outer clutch 71 is cylindrically formed which is extended to the lower portion thereof, and includes an integrally formed guide hole forming portion which includes first and second guide holes 78a and 78b formed at both sides of the guide hole forming portion, into which both ends of the guide pin 70 are vertically slidably mounted, as shown in FIG. 4. In this case, the guide pin 70 passes through the piston rod 61, the first and second elevating guide holes 54a and 54b, and the first and second guide holes 78a and 78b, simultaneously, and if the first hinge 21 rotates together with rotation of the door, and thus the camshaft 50 rotates, the guide pin 70 moves in the vertical down direction along the first and second guide holes 78a and 78b. Simultaneously, the actuator 60 rotates at the state of being elastically supported to the return spring 67 along the first and second elevating guide holes 54a and 54b and descends by a prescribed distance. Therefore, the camshaft 50 having the first and second elevating guide holes 54a and 54b, the guide hole forming portion having the first and second guide holes 78a and 78b, and the guide pin 70 constitutes a rotational/linear motion converter playing a role of converting a rotational motion of the door 21, that is, the shaft 51 into an up-and-down linear motion of the piston 62 connected to the piston rod 61.

In FIG. 1, reference numerals 81, 82, 83, 87 and 88 denote an 0-ring, respectively, a reference numeral 84 denotes a packing, a reference numeral 85 denotes a bushing, and a reference numeral 86 denotes a thrust bearing. The thrust bearing 86 plays a role of reducing the rolling friction and the noise generated between the lower surface of the introvert projection of the outer clutch 71 fixed to the central body 15 and the upper side of a cylindrical body 53 of the camshaft 50 when the camshaft 50 rotates.

1-3. Elevating guide structure of actuator

Hereinbelow, the elevating guide structure of the actuator 60 will be described in detail. In addition, a clutching process of the clutch unit for controlling the elastic force of the torsion spring 76 for reinforcing the closing force of a door will be described together.

FIGS. 6A through 6D are top sectional diagrams which sequentially show the operating state of a clutch unit according to the opening of a door, respectively. FIGS. 7A through 7C are partially enlarged sectional views which sequentially show the hydraulic flow when an actuator descends according to the opening of a door according to the first preferred embodiment of the present invention, respectively. FIGS. 7D and 7E are partially enlarged sectional views which sequentially show the hydraulic flow when the actuator ascends according to the closing of the door according to the first preferred embodiment of the present invention, respectively. Firstly, the first and second elevating guide holes 54a and 54b formed in the cylindrical body 53 of the camshaft 50 operate with the door opening angle as shown in FIG. 3, and are divided into four sections "a" through "d," which guide the elevating of the piston unit, that is, a first section "a" of the door opening angle of 0-15°, a second section "b" of the door opening angle of 15-90°, a third section "c" of the door opening angle of 90-130° and a fourth section "d" of the door opening angle of 130-160°.

Among the four sections "a"-"d," the first section "a" is a section that the opening angle in which the piston unit 62 of the actuator 60 ascends and descends is determined in the range of 0-15° and a cam diagram angle α of the first and second elevating guide holes 54a and 54b is set a range of 45-65° which is relatively bigger than an angle β of the second section "b" to thus enhance an efficiency of ascending the piston unit 62 and supplementing the closing force loss due to the resistance of the oil-hydraulic circuit and the proportional degradation of the restoring force of the return spring 67. Here, the state of oil-hydraulic circuit corresponds to the state shown in FIG. 7B. However, the oil flow direction of FIG. 7B shows the case of opening a door.

In the first section "a," that is, when the opening angle is in the range of 0-15°, the elastic restoring force of the return spring 67 is nearly consumed, since the return speed of a door is limited to a certain speed and delayed in advance at the section of 90-15° by the check valve 631 for the safety of a user during the closing of the door. However, in order to complete the automatic return of the door, a latch installed at the door must have a closing force so as to be combined with a lock installed at a door frame.

For this purpose, the hinge apparatus according to the present invention includes the clutch unit 700 which is clutched at the opening angle of 30° at the automatic return time of the door, particularly, a large-size door, as will be described later, stops the reverse twisting of the torsion spring 76 when the opening angle exceeds 30°, and releases the clutching operation when the opening angle is less than 30° to thus transfer the restoring force of the torsion spring 76 which has been reversely twisted to the camshaft 50. Therefore, in the first section "a," the check valve 631 does not operate at the door opening time and the torsion spring 76 is reversely twisted proportionally to the opening angle. The return spring 67 is also compressed proportionally to the opening angle. However, at the automatic return time of a door, the clutching operation of the clutch unit 700 is released from the opening angle less than 30° and the restoring force supplied from the torsion spring 76 which is in the reverse twisted state makes the inner clutch 73 and the camshaft 50 rotate in the right-hand screw direction. Consequently, the elastic force of the torsion spring 76 is added to the elastic force of the return spring 67 ascending the piston unit 62 to accordingly make the door completely returned, that is, locked. In this case, since most of the elastic force generated at the door opening time can be nearly reduced to the door closing force in comparison with the conventional hinge apparatus having the double camshaft structure, the efficiency of ascending the piston unit 62 can be enhanced to thus supplement loss of the door closing force. Moreover, in the second section "b," that is, when the opening angle is in the range of 15-90°, the check valve 631 does not operate at the door opening time and the torsion spring 76 is reversely twisted proportionally to the opening angle, in the range of 15-30° when the working angle of the clutch unit 700 is set as 30° for example. In addition, the return spring 67 is compressed proportionally to the opening angle. Moreover, at the time of the opening of the door, the reverse twisting of the torsion spring 76 is stopped in the range of the opening angle of 30-90° according to the operation of the clutch unit 700, and only the return spring 67 is compressed according to the descending of the piston unit 62.

In the conventional hinge apparatus, as the opening angle of the door is changed from 0°, that is, the completely closed state, to 160°, that is, the completely opened state, at the time of opening the door, the opening force required for op ening th e door increases directly p roportionally to th e op ening angle. Accordingly, it needs much force to open the door from the second section "b," that is, the opening angle of 15°. However, the present invention needs the opening force similar to that of the conventional case, in order to preserve the closing force of the door in the first section "a," but it needs the opening force which is greatly reduced in comparison with the section of the opening angle of less than 30° since the reverse twisting of the torsion spring 76 can be stopped from the opening angle of 30° of the second "b" according to the operation of the clutch unit 700, to thereby easily open a heavy large-size door.

In the meantime, in the second section "b," the cam diagram angle β of the first and second elevating guide holes 54a and 54b is set to be in the range of 10-45° which is relatively smaller than the angle α of the first section "a." As a result, when a door is opened, the rotating efficiency of the camshaft 50 is proportionally increased to thus supplement an opening force rising edge increasing proportionally to the opening of the door.

Moreover, in the third section "c" where the piston unit 62 is stopped, that is, in the range of the opening angle of 90-130°, the cam diagram angle is set to be zero to thus block the automatic return by the return spring 67. Here, the angle of the state where the door has been opened is maintained, and the largest restoring force of the return spring 67 works. The fourth section "d" is formed to be inclined upwards, and is a stopping power strengthening section where the guide pin 70 is stopped to be unable to move due to a stopper function. In this case, it is possible to extend the fourth section "d" so that the door opening angle is in the range of 130-180°.

In the meantime, in the case that the guide pin 70 ascends due to the repulsive power of the compressed return spring 67, the fluid pressure of the upper chamber 91 works greater than the elastic force of the return spring 67 in the vicinity of a limit in which the piston unit 62 can ascend. Accordingly, the piston unit 62 can abruptly descend in the reverse direction.

Moreover, the guide pin 70 may cause the internal noise and the damage of the internal components due to the irregular motion at the initial time entering into the second section "b" from the third section "c." To prevent these problems, it is preferable that a border between a first cam diagram sustenance portion 544 and a second cam diagram sustenance portion 545 of the first and second elevating guide holes 54a and 54b are formed in the form of a curved surface, respectively.

Moreover, the first cam diagram sustenance portion 544 and the second cam diagram sustenance portion 545 are set to have opposing curved surfaces at regular intervals with respect to the elevating guide hole 54a.

1-4. Fluid pressure control rod structure

The fluid pressure control rod 45 of the first preferred embodiment includes a high-speed section (Fast) setting portion 45a having a large amount of the flow of oil and a low-speed section (Slow) setting portion 45b having a small amount of the flow of oil, both which are disposed up and down in order to be suitable for the control of a single oil-hydraulic circuit as illustrated in FIGS. 7A through 7E. The high-speed setting portion 45a is set as an identical diameter, so that approximately half the oil flow can be made so as to make a relatively large amount of oil flow in comparison with an amount of the flow of oil, when the check valve 631 does not operate (at an OFF state), that is, at the door opening time like the descending of the piston. The low-speed section (Slow) setting portion 45b is tapered so that the diameter thereof increases from the upper portion to the lower portion. Accordingly, an amount of the flow is varied by 1/2-1/80 approximately, as the piston unit 62 ascends, in comparison with an amount of the flow of oil of the case that the check valve 631 does not operate (at an OFF state).

In this case, in the section where even a part of the high-speed setting portion 45a does not enter the inside of a first oil path 68a when the piston unit 62 ascends, an amount of the flow of oil moving from the upper chamber 91 to the lower chamber 93 becomes large and the door return can be made at a high speed.

Moreover, in the section where a part of the low-speed setting portion 45b does not enter the inside of the first oil path 68a when the piston unit 62 ascends, an amount of the flow of oil moving from the upper ch amber 91 to the lower chamber 93 gradually increases according to the ascending position of the piston unit 62 and a reduction in the restoring force of the return spring can be compensated for.

The high-speed setting portion 45a and the low-speed setting portion 45b set the length of each section variably according to an object to which the automatic return hinge apparatus is applied. Further, an amount of taper in the low-speed setting portion 45b is determined. For example, since doors such as constructional materials (fire preventive steel iron gates etc.) should be firmly shut, initiation of the high-speed setting portion 45a is initiated from for example, the door opening angle of 30°. However, the door opening angle starts from for example 5° in the case of the miniature doors for electric home appliances or the doors for the indoor rooms. In addition, since the high-speed setting portion is unnecessary in the case of up-and-down rotating type doors like Kimchi refrigerators in which Kimchi is a Korean fermentation food, the high-speed setting portion 45a is not employed in the up-and-down rotating type doors and only a low-speed setting portion 45b is employed therein, respectively.

1-5. Operation of hinge apparatus

The entire operation of the hinge apparatus according to the invention will illustrated below with reference to FIGS. 6A-6D and 7A-7E. In this case, the clutch unit 700 shown in FIGS. 6A-6D is set as a clutching starting angle of 90°.

However, since the hinge apparatus of the large-size door employing both the torsion spring and the return spring will be described, the operation of the hinge apparatus will be described for the case where the clutching starting angle is set as 30°as an example.

1-5-1. At the door opening time

Firstly, when a door is opened from the state and where the door has been closed, that is, from the state where the door has been stopped, as shown in FIGS. 6A and 7A, an oil-hydraulic circuit is set in the hinge apparatus according to the first preferred embodiment of the present invention for the as shown in FIG. 7B. That is, when the door is opened, the external rotational power is delivered to the shaft 51 of the camshaft 50 via the first hinge 21. Accordingly, the internal components operate as follows. When a user opens the door at the initial state of FIGS. 6A and 7A which show the state where the door has been closed, the torsion spring 76 is reversely twisted to thus generate the elastic force, while the shaft 51 of the camshaft 50 and the inner clutch 73 rotate in the left-handed screw direction, at the state including a pair of the roller pins 75 as shown in FIG. 6B. Simultaneously, the rotational force of the left-handed screw direction is transferred to the camshaft 50. Therefore, the guide pin 70 whose both end portions are inserted into a pair of the first ad second guide holes 78a and 78b which are formed in the first and second elevating guide holes 54a and 54b and the outer clutch 71, moves downwards along the first and second elevating guide holes 54a and 54b. according to the rotation of the camshaft 50.

In this case, as shown in FIG. 7B, the power to urge the piston unit 62 to move to the down direction is applied to the piston unit 62 operating with the guide pin 70 and the piston rod 61 which move to the down direction.

Accordingly, the oil positioned in the lower side of the piston unit 62, that is, the lower chamber 93 moves to the upper chamber 91 through the first oil path 68a and the second oil path 68b. Simultaneously, the fourth oil path 68d is opened, while a p lurality of opening and cl osing control bal Is 63a o f th e overp ressure prevention unit 63 move upwards. Accordingly, the oil moves to the upper chamber 91 through the fourth oil path 68d and the third oil path 68c. That is, at the door opening time, the check valve 631 is closed, that is, in the OFF state. As a result, a large amount of oil rapidly moves from the lower chamber 93 to the upper chamber 91. As such, the guide pin 70 moves in the first and second sections "a" and "b" like the operating state at the first and second elevating guide holes 54a and 54b, while the support nut 66 of the actuator 60 descends while compressing the return spring 67.

Moreover, if the door opening angle exceeds 30° as shown in FIG. 7C, while the piston rod 61 moves downward, the low-speed setting portion 45b of the fluid pressure control rod 45 which is taper formed enters into the first oil path 68a. As a result, an amount of the oil passing through the first oil path 68a is decreased. However, the piston unit 62 rapidly descends since most of much amount of oil rapidly moves from the lower chamber 93 to the upper chamber 91 through the check valve 631 which is in the OFF state.

Furthermore, when the opening angle of the door becomes 30°, a pair of the roller pins 75 are seceded from the first insertion hole 74a of the inner clutch 73 and is inserted to the second insertion hole 74c of the outer clutch 71, as shown in FIG. 6C. When the opening angle of the door becomes 30° or greater, the rotation of the inner clutch 73 is suspended and only the shaft 51 of the camshaft 50 rotates as shown in FIG. 6D. Accordingly, an increase in the elastic force of the torsion spring 76 is stopped based on the opening angle of the door of 30°. In this case, the roller pin 75 hanging on the first insertion hole 74a is inserted up to the center or less. Therefore, if he roller pin 75 gets twisted by the torsion spring 76, in FIG. 6C, the power spreading out to the outside works and gets to go out through the second insertion hole 74c, when reaching the second insertion hole 74c. Moreover, when the camshaft 50 continuously rotates at the state where an increase in the elastic force of the torsion spring 76 is stopped, the guide pin 70 gets to reach the third section "c" in which the door opening angle is 90°. As the movement of the guide pin 70 is limited by the first stopper 542 in the third section "c" of the first ad second elevating guide holes 54a and 54b, the piston unit 62 is maintained as the stationary state at the state of being positioned at the lower dead centre.

Therefore, when a door of the opening angle of 30-90° which users generally wisely use is opened in the present invention, the opening force is greatly reduced in comparison with that in the section of the opening angle less than 30° to thereby easily open a large-size heavy door.

In the meantime, in the above preferred embodiment, it is possible that the third section "c" where the door opening angle is in the range of 90-130° is set as the stationary section. However, it is possible to modify the stationary section into for example, the range of 60-100° or 90-100°by shifting the location of the first stopper 542 of the first and second elevating guide holes 54a and 54b or reducing or increasing the width of the first stopper 542 according to a need.

1-5-2. At the door closing time

In the meantime, when a door is closed, the door is closed so that the opening angle of the door becomes less than 90° as shown in FIG. 7D. Otherwise, a user opens the door and lets the door alone in the door opening angle of less than 90°, the door performs the automatic return operation to the initial position. Assuming that the opening angle of a door is 90°, that is, when the door is in the stationary state, if a user rotates the door so that the external force is a little delivered to the camshaft 50 in the right-hand screw direction, the guide pin 70 passes the first stopper 542 and deviates from the third section "c." In this case, the elastic force of the return spring 67 which is in the compressed state should be set larger than the pressure of the oil contained in the upper chamber 91 and applied to the upper surface of the piston unit 62.

Then, the piston unit 62 begins to move upwards by the strong repulsive power of the compressed return spring 67. The guide pin 70 connected to the piston unit 62 ascends vertically along the second section "b" of the first and second elevating guide holes 54a and 54b, that is, the elevating guide portion 541 of the slow tilt angle of 10-45° and the first and second guide holes 78a and 78b. Consequently, the camshaft 50 rotates in the right-hand screw direction to thereby try to return the door to the initial position.

Here, if the oil in the upper chamber 91 receives a pressure by the piston unit 62 ascending as shown in FIG. 7D, the oil is pressurized to move to the lower chamber 93 through the third and fourth oil paths 68c and 68d. In this case, each check valve 631 is at the ON state as a plurality of opening and closing control balls 63a each close a plurality of fourth oil paths 68d. Accordingly, the oil is unable to flow through the fourth oil paths 68d and passes through the space between the cylinder body 53 and the piston rod 61 and then passes through the second and first oil paths 68b and 68a to then be transferred to the lower chamber 93. As a result, the piston unit 62 ascends at a first speed of a relatively low speed in the section of the range of 90-30°.

In this case, according to the ascending of the piston unit 62, the repulsive power of the return spring 67 gradually decreases. However, the low-speed setting portion 45b which has been inserted into the first oil path 68a gradually moves to a portion whose diameter is small. Thus, an amount of the flow of the oil passing through the first oil path 68a gradually increases. As a result, the first speed can be consistently maintained.

Thereafter, the piston unit 62 ascends and enters the range of the opening angle of 30-0°, the low-speed setting portion 45b runs away from the first oil path 68a to the lower chamber 93, as shown in FIG. 7E. That is, only the high-speed setting portion 45a is inserted into the first oil path 68a. The oil in the upper chamber 91 passes through the space between the cylinder body 53 and the piston rod 61 and then passes through the second and first oil paths 68b and 68a to then be transferred to the lower chamber 93 with an amount of the flow of oil more than that in the section of the range of 90-30°. As a result, the piston unit 62 ascends at a second speed faster than the first speed.

In this way, in determining from only the oil-hydraulic circuit, the piston unit 62 ascends at the first speed of the relatively low-speed in the section of the opening angle of 90-30°, and the piston unit 62 ascends at the second speed in the section of the opening angle of 30-0°. Accordingly, a door is closed at a low-speed with a small amount of the flow of oil in comparison with the door opening time. Therefore, in the section of the opening angle of 90-30° h aving an effect on the incoming and outgoing of users, the door is closed at the first speed which is the low speed, to thereby prevent the safety accident and inconveniences from occurring according to the abrupt return of the door. However, in the section of the opening angle of 30-0° which does not have an effect on the incoming and outgoing of users, the door is closed relatively rapidly to thus reinforce the closing force of the door. Thereafter, according to the ascending of the piston unit 62, the shaft 51 rotates in the right-hand screw direction and the opening angle of a door becomes 30° or less. In this case, the roller pin 75 is seceded from the second insertion hole 74c of the outer clutch 71 and is inserted into the first insertion hole 74a of the shaft 51. Here, the roller pin 75 hanging on the second insertion hole 74c is inserted up to the center or less thereof. Therefore, the inner clutch 73 which receives the rotational force of the initial setting direction, that is, the right-hand screw direction by the elastic restoring force of the torsion spring 76, applies the rotational force to the roller pin 75. Then, the roller pin 75 secedes from the second insertion hole 74c and rotates in the right-hand screw direction together with the inner clutch 73.

Accordingly, the stopped inner clutch 73 receives the rotational force of the initial setting direction, that is, the right-hand screw direction by the elastic restoring force of the torsion spring 76, and applies the rotational force of the right-hand screw direction to the shaft 51 via the roller pin 75. As a result, the door closing force is additionally reinforced by the return spring 67.

Thereafter, when the door opening angle passes 15° and is in the range of 15-0°, the oil-hydraulic circuit is set in the same manner as that of the case that the door op ening angle is in th e range of 30 -15°. However, th e tilt angle o f 45-65° of the first section "a" of the elevating guide portion 541 is set relatively larger than that of the tilt angle of 10-45°of the second section "b." Consequently, the restoring force of the return spring 67 is reduced, but the frictional resistance of the elevating guide portion 541 also decreases. Accordingly, the elevating speed of the piston unit 62 is accelerated at a third speed. Therefore, the door is returned to the initial position and becomes at a locked state by the latch of the door. Here, the piston unit 62 returns to the location of the initial state as shown in FIG. 7A. As described above, the hinge apparatus according to the present invention employs both the return spring 67 and the torsion spring 76, to thereby prevent the loss of the door closing force at the door closing time, and remove the compression repulsive power of the torsion spring 76 from the door opening angle of 30° or greater in which the clutching of the clutch unit is accomplished at the door opening time. Accordingly, in comparison with the case having no clutching, the hinge apparatus according to the present invention can easily open a heavy, large-size door with relatively small power.

In the description of the first preferred embodiment, it is assumed that the high-speed setting portion 45a of the fluid pressure control rod has been at the state of the door opening angle of 30° which is suitable for a fire prevention door. However, the door opening angle is set as 5°in the case of for the miniature doors for electric home appliances or the doors for the indoor rooms, etc. In addition, the up/down rotational doors which are applied in Kimchi refrigerators for use in a storage unit for storing a fermentation food such as Kimchi which is one of Korean traditional foods, can be configured with only the low-speed setting portion 45b of a tapered shape, without the high-speed setting portion 45a.

2. Second embodiment FIG. 8 is a partially enlarged sectional view showing the characteristic portion of the automatic return hinge apparatus having the structure that a check valve is embedded in a piston according to a second embodiment of the present invention. When a door is rapidly closed by the external force like strong wind, the automatic return hinge apparatus according to the above-described first preferred embodiment, includes an overpressure prevention valve preventing damage of all kinds of 0-rings for maintenance of air-tightness of a body and a piston unit in which the overpressure prevention valve is separated from the piston unit. However, the automatic return hinge apparatus according to the second embodiment of the present invention has a difference from that of the first embodiment of the present invention, in a point of view of having the structure that the overpressure prevention valve is removed from that of the second embodiment and the check valve 633 is embedded in the piston unit 62a. The structure and operation of the check valve 633 in the second embodiment are substantially identical to those of the check valve 631 in the first preferred embodiment.

Therefore, since the structure and the opening and closing operations of the check valve 633 and the piston unit 62a in the second embodiment are substantially same as those of the first preferred embodiment, like references denote like elements. Accordingly, the detailed description thereof will be omitted.

3. Variation of the first preferred embodiment

FIG. 9A is a cross-sectional view which shows an automatic return hinge apparatus showing a variation of the first preferred embodiment of the present invention, and FIG. 9B is a cross-sectional view which shows a check valve having a notch portion applied to the variation of the first preferred embodiment shown in

FIG. 9A.

When compared with the first embodiment, a variation shown in FIG. 9A includes a notch portion 69 which applies uniform damping power to the check valve 632 at the door closing time as shown in FIG. 9B. In addition, the variation shown in FIG. 9A has the structure from which the oil path passing through the inner portion of the piston rod 610 and the fluid pressure control rod 45 whose leading end portion is inserted into the oil path have been removed.

In the above-described automatic return hinge apparatus according to the variation of the present invention, the operation at the door opening time is substantially same as that of the first embodiment, and has a difference only in the case of the door closing time.

That is, if the piston unit 620 ascends according to the closing of the door, the oil of the upper chamber 91 receives a pressure with the ascending piston unit 620 and moves to the lower chamber 93 through the third and fourth oil paths 68c and 68d, respectively. In this case, a plurality of opening and closing control balls

63a of the check valve 632 each closes a plurality of fourth oil paths 68d, respectively. Accordingly, the oil flows out to the lower chamber 93 through a narrow single notch portion 69 by a small amount of oil, each time. As a result, the piston unit 620 ascends at a first speed of a low speed in the section of the range of 90-30°.

Thereafter, when the piston unit 620 ascends and reach the opening angle of 30°, the clutch unit 700 starts to operate like the first embodiment. Accordingly, the clutch unit 700 receives the rotational force of the initial setting direction, that is, the right-hand screw direction by the elastic restoring force of the torsion spring 76, and applies the rotational force of the right-hand screw direction to the shaft 51 via the roller pin 75. As a result, the door closing force is additionally reinforced by the return spring.

Moreover, when the door opening angle passes 15° and advances in the range of 15-0°, the frictional resistance of the elevating guide portion 541 decreases more than that of the second section "b" according to setting of the tilt angle of 45-65° of the first section "a" of the elevating guide portion 541. Accordingly, the elevating speed of the piston unit 62 is accelerated at a second speed. Therefore, the door is returned to the initial position and becomes at a locked state by the latch of the door. Here, the piston unit 62 returns to the location of the initial state as shown in FIG. 7A.

As described above, in the case of the hinge apparatus according to the variation of the present invention, the check valve 632 operates at the door closing time of the opening angle of 90-30° and thus the oil in the upper chamber 91 flows into the lower chamber 93, through only the narrow notch portion 69. Accordingly, an amount of the flow of oil is greatly reduced and thus the piston unit 620 slowly ascends at a certain speed. The setting of such a slow door closing speed is the oil-hydraulic circuit which is suitable for products which require that the door closing be accomplished within certain time, for example, four seconds and do not need a minute speed control like for example, refrigerators. 4. Third preferred embodiment

FIG. 10 is a lengthy direction cross-sectional view showing a slim type automatic return hinge apparatus having a double oil-hydraulic circuit according to a third preferred embodiment of the present invention. FIGS. 1 IA through 11C are partially enlarged sectional views which sequentially show the hydraulic flow when an actuator descends at the opening time of a door according to the third preferred embodiment of the present invention. FIGS. HD and HE are partially enlarged sectional views which sequentially shows the hydraulic flow when the actuator ascends according to the closing of the door.

On the one hand, the first and second embodiments relate respectively to the hinge apparatus applied to the heavy, large-size architectural doors like fire prevention door and the doors for the large -capacitive electric home appliances for example. On the other hand, the hinge apparatus of the third preferred embodiment relates to the slim type automatic return hinge apparatus in which the diameter of the body is small so that the hinge apparatus can be embedded in the above-described heavy, large-size door, especially, a door for large-size electric home appliances.

The structure of the hinge apparatus according to the third preferred embodiment of the present invention employs both a return spring 167 and a torsion spring 176 like the first preferred embodiment. The overall configuration thereof is similarly accomplished.

Hereinafter, the detailed description of the configuration of the third embodiment which is same as that of the first preferred embodiment will be omitted. The configuration of the third embodiment different from that of the first embodiment, that is, the structure of configuring two independent oil-hydraulic circuits and supplementing the damping power which is reduced as the hinge apparatus slims will be described in detail.

Firstly, the hinge apparatus according to the third preferred embodiment of the present invention includes a first fixing member 121 fixed to one end of a door frame of a refrigerator and a second fixing member 123 fixed to a door.

In this case, the first fixing member 121 is fixed to the upper end of the shaft 151 of the camshaft 150 through a connector 100. One end of the second fixing member 123 is fixed to an upper cap 131 fixed to a body 113 by a plurality of fixing pieces 132, in order to rotate the body 113 according to the rotation of the door at the door opening time, and descend an actuator 160 to thereby activate the oil-hydraulic circuit in the oil chamber into operation. Moreover, the actuator 160 has the structure that first and second piston units 162a and 162b are combined with the center and the bottom side of a piston rod 161 at a prescribed distance, in which the piston rod 161 is axially movably supported between the fist and second piston units 162a and 162b, and an isolation unit 200 is fixed to the body 113. The isolation unit 200 is disposed between a first lower chamber 193a and a second upper chamber 191b, in order to partition first and second upper and lower chambers 191a and 193a; 191b and 193b by the first and second piston units 162a and 162b. Additionally, the piston rod 161 in the actuator 160 includes a first oil path

168a, a second oil path 168b mutually communicating the first oil path 168a and the first upper chamber 191a, and a third oil path 168c mutually communicating the first oil path 168a and the first lower chamber 193a, so that the oil loaded in the first lower chamber 193a can move to the first upper chamber 191a according to the descending of the first piston unit 162a, that is, at the door opening time. Furthermore, the piston rod 161 in the actuator 160 includes a fourth oil path 168d which mutually communicates the first oil path 168a and the second upper chamber 191b so that the oil loaded in the second lower chamber 193b can move to the second upper chamber 191b according to the descending of the second piston unit 162b.

In this case, one end of the fluid pressure control rod 145 for controlling the oil path is inserted into the first oil path 168a, and the other end thereof is fixed to a support supported in the lower cap 133. The fluid pressure control rod 145 in the third embodiment includes a pair of high-speed (Fast) setting portions 145a and 145c having a large amount of the flow of oil and a pair of low-speed (Slow) setting portions 145b and 145d having a small amount of the flow of oil, so as to be suitable for the control of the double oil-hydraulic circuit as illustrated in FIG. HA and HB, in which both the high-speed (Fast) setting portions 145a and 145c and the low-speed (Slow) setting portions 145b and 145d are alternately arranged.

The pair of the high-speed setting portions 145a and 145c are set as an identical diameter, so that approximately half the oil flow can be made so as to make a relatively large amount of oil flow in comparison with an amount of the flow of oil, when the check valves 170 and 171 do not operate (at an OFF state), that is, at the door opening time like the descending of the piston. The pair of the low-speed (Slow) setting portions 145b and 145d are tapered so that the diameter thereof increases from the upper portion to the lower portion. Accordingly, an amount of the flow is varied by 1/2-1/80 approximately, as the piston units 162a and 162b ascend, in comparison with an amount of the flow of oil of the case that the check valves 170 and 171 do not operate (at an OFF state).

In this case, in the section where the pair of the high-speed setting portions 145a and 145c correspond to the third and fourth oil paths 168c and 168d when the piston units 162a and 162b ascend, an amount of the flow of oil respectively moving from the first and second upper chambers 191a and 191b to the first and second lower chambers 193a and 193b becomes remarkably large and the return of the door can be made at a high speed. Moreover, in the section where the pair of the low-speed setting portions

145b and 145d correspond to the third and fourth oil paths 168c and 168d when the piston units 162a and 162b ascend, an amount of the flow of oil respectively moving from the first and second upper chambers 191a and 191b to the first and second lower chambers 193a and 193b gradually increases according to the ascending positions of the piston units 162a and 162b and a reduction in the restoring force of the return spring can be compensated for.

The pair of the high-speed setting portions 145a and 145c and the pair of the low-speed setting portions 145b and 145d set the length of each section variably according to an object to which the automatic return hinge apparatus is applied. Further, an amount of taper in the low-speed setting portions 145b and 145d is determined.

For example, since doors such as constructional materials (fire preventive steel iron gates etc.) should be firmly shut, initiation of the high-speed setting portions 145a and 145c is initiated from for example, the door opening angle of 30°. However, the door opening angle starts from for example 5° in the case of the miniature doors for electric home appliances or the doors for the indoor rooms. In addition, since the high-speed setting portions 145a and 145c are unnecessary in the case of up-and-down rotating type doors like Kimchi refrigerators in which Kimchi is a Korean fermentation food, the high-speed setting portions 145a and 145c are not employed in the up-and-down rotating type doors and only the low-speed setting portions 145b and 145d are employed therein, respectively.

In the meantime, first and second overpressure prevention units 163a and 163b include overpressure prevention valves 630a and 630b which are elastically installed by first and second dish-shaped springs 164a and 164b at the lower portions of the first and second piston units 162a and 162b, respectively. In this case, the first and second dish-shaped springs 164a and 164b are supported by first and second snap rings 165a and 165b, respectively, to thereby prevent the first and second dish-shaped springs 164a and 164b from being pushed along the piston rod 161 by the overpressure at the time of generation of the overpressure and to thus make the overpressure prevention valves 630a and 630b smoothly operate. Moreover, the hinge apparatus according to the third preferred embodiment included a plurality of check valves 170 and 171 which are same as those of the first preferred embodiment in the first and second overpressure prevention units 163a and 163b. The return spring 167 is arranged in the lower part of the actuator 160. The clutch unit 710 is arranged on the top of the cylindrical body 153 of the camshaft 150. The torsion spring 176 is arranged between the clutch unit 710 and upper cap 131.

Furthermore, a basic mechanism which elevates the actuator 160 and in this case, controls the ascending and descending speeds of a door (that is, the door opening and closing speeds) is also formed in the same manner as that of the first preferred embodiment.

The above-described third preferred embodiment is substantially same as the first embodiment, excepting that two closed circuit chambers are formed in order to supplement the damping power which reduces as the hinge apparatus slims as described above, and to configure two independent oil-hydraulic circuits in the longitudinal direction, that is, to add an additional independent oil-hydraulic circuit.

Moreover, considering the operation of the hinge apparatus, the first and second piston units 162a and 162b are positioned in the top dead center of each chamber in the third preferred embodiment as shown in FIG. 1 IA in the case that the door opening angle is 0° at the door opening time. In the meantime, when the first and second piston units 162a and 162b descend as shown in FIG. HB in the case that the door opening angle is in the section of the range of 0-30°, the first and second check valves 170 and 171 are in the OFF state, and the oil of the first and second lower chambers 193a and 193b rapidly moves to the first and second upper chambers 191a and 191b through the first and second check valves 170 and 171, and the first to fourth oil paths 168a~168d in the piston rod 161. Moreover, the oil in the first and second lower chambers 193a and 193b rapidly moves to the first and second upper chambers 191a and 191b as shown in FIG. HC through the first and second check valves 170 and 171 and the first to fourth oil paths 168a- 168d in the piston rod 161 in the case that the door opening angle is in the section of the range of 30-90°. Only in the case that the door opening angle is in the section of the range of

0-30°, the oil moving through the first to fourth oil paths 168a- 168d corresponds to the high-speed setting portions 145a and 145c, and an amount of the flow of oil increases a little in comparison with the case that the door opening angle corresponding to the low-speed setting portions 145b and 145d is in the section of the range of 30-90°. However, most of the oil moves through the first and second check valves 170 and 171.

Since the operation of the clutch unit 700 is performed in the same manner as that of the first preferred embodiment at the door opening time, an increment in the elastic force of the torsion spring 176 stops in the case that the opening angle of a door exceeds the clutching start angle, for example, 30°. Therefore, the door opening force is greatly reduced at the time of opening a door after the clutching start angle, to thereby easily open the heavy, large-size door.

In the meantime, at the closing time of a door, in the case that the door opening angle is in the section of the range of 90-30°, as shown in FIG. HD, the oil in the first and second upper chambers 191a and 191b moves to the first and second lower chambers 193a and 193b at a first speed which is the low speed through the first to fourth oil paths 168a^~168d in the piston rod 161 since the first and second check valves 170 and 171 become in the ON state.

In this case, the oil moving through the first to fourth oil paths 168a- 168d is determined in correspondence to the taper type low-speed setting portions 145b and 145d, and an amount of the flow of oil gradually increases in order to compensate for a decrease in the restoring force of the return spring. Thereafter, in the case that the door opening angle is in the section of the range of 30-0° as shown in FIG. HE, the oil in the first and second upper chambers 191a and 191b moves to the first and second lower chambers 193a and 193b at a second speed which is the low speed through the first to fourth oil paths 168a- 168d in the piston rod 161, since the first and second check valves 170 and 171 become in the ON state.

In this case, the oil moving through the first to fourth oil path 168a-168d is determined in correspondence to the high-speed setting portions 145a and 145c, and a decrease in the restoring force of the return spring has been compensated for and simultaneously the closing force of a door has been supplemented. As described above, when the opening angle of a door is at the state of the clutching start angle, that is, 30° or less, the clutching of the clutch unit 700 is released or canceled and thus the elastic restoring force of the torsion spring 76 is applied, to thereby additionally increase the closing force of the door by the return spring 167. Moreover, when the door opening angle is in the section of the range of 15-0°, the elevating speed of the piston units 162a and 162b can be accelerated at a third speed according to the setting of the large tilt angle of the elevating guide portion 541. Therefore, the door returns to the initial position and becomes at the locked state by the latch of the door.

As described above, the hinge apparatus according to the third preferred embodiment, adds at least one oil-hydraulic circuit to compensate for the damping power which decreases instead of reducing the diameter of the body playing a role of a housing into the slim type, to thereby provide sufficient damping power to control the ascending speeds of the piston units 162a and 162b.

Moreover, the hinge apparatus according to the third preferred embodiment also employs both the return spring and the torsion spring, to thereby prevent the loss of the closing force of the door and easily open a large-size heavy door with a small amount of force from which the compression repulsive power of the torsion spring has been removed after a certain angle or more by the operation of the clutch unit at the door opening time.

As described above, considering the operation of the hinge apparatus according to the third embodiment, the first preferred embodiment has the structure that a door, that is, an actuator is connected to the camshaft 50, and the central body 15 is connected to a door frame, that is, a fixed body, to thereby enable the camshaft 50 to rotate according to the rotation of the door. However, in the third preferred embodiment, the camshaft 150 is fixed to the door frame through the first fixing member 121, and the single body 113 is fixed to a door through the second fixing member 123. Therefore, there is only a difference between the first and third embodiments, in the point of view that the body 113 is rotated as an actuator and the camshaft 150 is fixed as a fastener, but the first and third embodiments are identically made in the point of view of elevating and driving the actuator 160.

Moreover, the hinge apparatus according to the third preferred embodiment of the present invention includes two independent oil-hydraulic closed circuits in the longitudinal direction, and a pair of check valves 170 and 171 which simultaneously operate according to the elevating of the actuator 160, respectively, in the close circuit. As a result, the sufficient damping power is provided so that a door is delayed at a certain speed in spite of employing the slim structure, that is, the door is automatically returned at a delayed speed.

In the above-described third preferred embodiment, the amount of the flow of oil in the duplex oil-hydraulic circuit is controlled by the check valves and the fluid pressure control rod. However, the upper oil-hydraulic circuit forms the first fluid pressure circuit including the notch portion providing the uniform damping power for the check valve at the door closing time, and the lower oil-hydraulic circuit forms th e second fluid p ressure circuit in wh ich th e fluid pressure control rod is inserted into the oil path formed in the piston rod so that an amount of the flow of oil, that is, the ascending speed of the piston can be variably controlled according to the ascending position of the piston, to then allow a combination of the upper and lower oil-hydraulic circuits. 5. Fourth embodiment

FIG. 12 is a lengthy direction cross-sectional view showing a slim type automatic return hinge apparatus having a ball type clutch unit and a double oil-hydraulic circuit according to a fourth preferred embodiment of the present invention. FIG. 13 is a perspective view showing the ball type clutch unit according to the present invention. FIGS. 14A through 14C are top sectional diagrams which sequentially show the operating state of the ball type clutch unit at the door opening time.

The automatic return hinge apparatus according to the fourth preferred embodiment is similar to that of the respective first to third embodiment in the point of view of em ploying th e dup lex oil-h ydraulic circuit for reinforcing th e damping power in order to seek after the slim type. However, the fourth embodiment differs from the first to third embodiments, in the point of view of employing a ball type clutch unit whose length is relatively short instead of employing the roller pin type clutch unit as in the first to third embodiments.

Therefore, in the case of the fourth embodiment, the same reference numbers are given to the same elements as the first to third preferred embodiments. The detailed description thereof will be omitted.

As shown in FIGS. 12 and 13, the ball type clutch unit includes: a clutch body 271 having a throughhole 271c at the central portion thereof; an axial disc

272 whose rotational axis 270 is combined with the throughhole 271c and which is faced with the clutch body 271 perpendicularly with the rotational axis; a body holder 274 which is disposed in opposition to the lower part of the axial disc 272, into the throughhole 274c of the central portion of which the rotational axis 270 is rotatably inserted, and which is fixed to a door by a fixing pin 275; and first and second balls 273a and 273b which move between the clutch body 271, the axial disc 272, and the body holder 274, when the body holder 274 rotates in one direction and the other direction, and selectively coupled with each other, to thus deliver the rotational force and to thereby selectively remove the compression repulsive power of the torsion spring 276 whose one end is combined with the body holder 274.

Hemispherical first and second inserting holes 271a and 271b are formed in the lower surface of the clutch body 271 so that the first and second balls 273a and 273b move between the clutch body 271, the axial disc 272, and the body holder 274, and are selectively combined with each other to deliver or block the rotational force of the body holder 274. First and second throughholes 272a and 272b are formed in the axial disc 272 so that the first and second balls 273a and 273b can pass through the first and second throughholes 272a and 272b. Hemispherical first and second lower insertion holes 274a and 274b are formed in the upper surface of the body holder 274.

A rectangular protrusion 271d which is combined with a shaft accommodation portion of a door frame in the upper side of the clutch body 271, when a hinge apparatus is installed in a door is protruded to the outside. An E-ring for suppressing the secession of the clutch body 271 from the rotational axis 270 extended through the throughhole 271c is combined with the leading end portion of the rotational axis 270 in the upper side of the protrusion 27 Id. Moreover, the upper end of the torsion spring 276 is fixed by a first fixing hall 278a in the lower portion of the body holder 274. The upper end of the torsion spring 276 is fixed by a second fixing hole 278b formed in the upper end of a shaft holder 277. A hexagonal lower portion of the rotational axis 270 is combined with a hexagonal through-groove formed at the central portion of the shaft holder 277. The hexagonal lower portion of the rotational axis 270 can be combined with the camshaft 150 of the oil-hydraulic circuit in a simple axial coupling structure.

The operation of the ball type clutch unit constructed as described above will be illustrated with reference to FIGS. 14A through 14C. In FIGS. 14A through 14C, the shaded portions represent the positions where the first and second balls 273a and 273b are positioned.

At the state of FIG. 14A, in which a door is closed, that is, when the door is at the initial state, the first and second balls 273a and 273b which are positioned between the first and second upper inserting holes 271a and 271b of the clutch body 271 and the first and second throughholes 272a and 272b of the axial disc 272 are blocked by the upper surface of the body holder 274.

When the door is opened at the state where the first and second throughholes 272a and 272b of the axial disc 272 are blocked by the upper surface of the body holder 274, and the body holder 274 fixed to the door rotates in the left-hand screw direction, the torsion spring 276 is reversely twisted. Here, if the body holder 274 continuously rotates as shown in FIG. 14B and thus the door opening angle reaches the clutching stopper start angle, for example, 30°, the first and second lower insertion holes 274a and 274b of the body holder 274 face the first and second balls 273a and 273b. In this case, because the body holder 274 is twisted, that is, is applied with a twisted force, the first and second balls 273a and 273b move to the first and second lower insertion holes 274a and 274b. Thereafter, when the body holder 274 continuously rotates according to the opening of the door, the body holder 274 and the axial disc 272 rotate together in the left-hand screw direction and the clutch body 271 maintains the stopped state, as shown in FIG. 14C. That is, if the clutching state is maintained, an increment of the elastic force of the torsion spring 276 stops, at the time of the rotation after the clutching starting angle, the opening force is greatly reduced and thus a user can easily open the heavy, large-size door.

Moreover, at the closing time of the door, when the door opening angle reaches the clutching stopper start angle, the clutching is released or canceled and the elastic force of the torsion spring 276 is added to the restoring force of the return spring. As a result, the door closing force increases.

6. Application of hinge apparatus

Since the structure and functional effects of the remaining elements of the slim type automatic return hinge apparatus according to the fourth preferred embodiment having the ball type clutch unit and the duplex oil-hydraulic circuit are same as those of the third preferred embodiment. The detailed description thereof will be omitted.

An application of the hinge apparatus 300 according to the fourth embodiment, as shown in FIG. 17, a rectangular protrusion 27 Id of the clutch body

271 which is embedded in one side well of the door 310 and is protruded from the hinge apparatus 300 is coupled with and fixed to the shaft accommodation portion 321 of the door frame 320, and the simple hinge apparatus 311 is rotatably supported by the door frame 320, at the lower portion of the door. In the application, the body 113 of the hinge apparatus 300 is pivoted around the rotational axis 270 and the simple hinge apparatus 300 as an axis together with the door 310.

In the meantime, it is possible that the automatic return hinge apparatus according to the respectively above-described third and fourth preferred embodiments does not cause any problems, and can separate the first hinge apparatus "A" made of the torsion spring and the clutch unit from the main body of the automatic return hinge apparatus. The reason is because the first hinge apparatus "A" and the second hinge apparatus "B" from which the first hinge apparatus "A" has been separated are combined with each other in a simple axial coupling structure.

FIG. 15 is a cross-sectional view showing an isolation structure of the slim type automatic return hinge apparatus according to the fourth embodiment of the present invention, and FIG. 16 is an illustrative view which illustrates the state where the separable automatic return hinge apparatus shown in FIG. 15 has been applied to a door.

The slim type automatic return hinge apparatus according to the fourth embodiment is divided into the first hinge apparatus "A" having the torsion spring 276 and the clutch unit 720 and the second hinge apparatus "B" having the return spring 167 and the oil-hydraulic circuit and having the automatic return function, by separating the shaft holder 277 and the guide hole forming portion 78, as shown in FIG. 15. In this case, as shown in FIG. 16, the slim type automatic return hinge apparatus according to the fourth embodiment can be configured as an application of the structure that the first hinge apparatus "A" is embedded in one side well of the door 310 and the rectangular protrusion 271d of the clutch body 271 which is protruded from the first hinge apparatus "A" is coupled with and fixed to the shaft accommodation portion 321 of the door frame 320, and the second hinge apparatus "B" is embedded in the upper portion of the door and the protruded shaft 151 of the second hinge apparatus "B" is fixed to the door frame 320.

In the application, the door rotates together with the body of the first and second hinge apparatuses "A" and "B" around the rotational axis 270 of the first hinge apparatus "A" and the shaft 151 of the second hinge apparatus "B."

Moreover, the automatic return hinge apparatus of the first preferred embodiment has been described with respect to the case that it is installed in a door and a frame using a hinge apparatus. However, the present invention is not thus restricted thereto but is possible to be applied with modes which are well-known. For example, it is possible that the body is formed into a single body and the body and the shaft are installed using the fixing members whose one end is fixed to in the door frame and the door for use in a refrigerator as in the third embodiment, respectively.

7. Variations

In the meantime, in the description of the first embodiment, the torsion spring 76 and the return spring 67 are combined in use. When the clutch unit 700 exceeds the opening angle of 30°, the oil-hydraulic control structure where the clutching operation is performed has been described. However, in the case of the slim type hinge apparatus according to the first embodiment of the present invention, the return spring is removed and only the torsion spring 76 can be provided to provide the restoring force for the actuator 60. Moreover, even in the case of the hinge apparatus according to the respective second to fourth preferred embodiments, the return spring is removed and only the torsion spring

76 can be provided to provide the restoring force for the actuator 60.

That is, in the case of the slim type automatic return hinge apparatus for the miniature doors for the electric home appliances and the architectural buildings except for the cases that require the large restoring force for the actuator like the large-size heavy doors, it is possible to provide the restoring force for the actuator with only the torsion spring 76. In this case, it is preferable that the clutching stopper start angle that the clutching of the clutch unit 700 is performed is set as for example, 90°.

The ball type clutch unit which has been described in the fourth embodiment can be applied to the other embodiments or variations. Moreover, in the above preferred embodiment, the ball type check valve has been described, but it is possible to be made of a sheet form.

[Industrial availability]

The automatic return hinge apparatus according to the present invention can compensate for the closing force loss of a door, and reduce the opening force of the door so as to be applied to the heavy large-size door. Further, the automatic return hinge apparatus according to the present invention can be applied in the inner side of various kinds of doors of a large size or a small size which require ultra-small type diameter in a built-in form.

As described above, the present invention has been described with respect to particularly preferred embodiments. However, the present invention is not limited to the above embodiments, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention. Thus, the protective scope of the present invention is not defined within the detailed description thereof but is defined by the claims to be described later and the technical spirit of the present invention.

Claims

[CLAIMS]

[Claim 1]

A hinge apparatus having an automatic return function for a door which has first and second hinges which are fixed to the door and a door frame, respectively, the automatic return hinge apparatus comprising: an upper body on a circumferential surface of which the upper side of the first hinge is integrally formed and whose upper end portion is blocked by an upper cap on the inner side surface of which a recess is formed; a lower body on a circumferential surface of which the lower side of the first hinge is integrally formed and whose lower end portion is blocked by a lower cap which is connected in a sealing manner; a central body on a circumferential surface of which one side of the second hinge is integrally formed and which is pivotally arranged between the upper and lower bodies; a shaft whose lower end portion is rotatably installed in the middle portion of the central body and whose upper end portion is inserted into the recess of the upper cap and is fixed to the upper body," a piston whose outer circumference is slidably installed along the inner circumferential surface of the central body and which divides the inner portion of the central body into upper and lower chambers," rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the piston when the rotational force of the door is applied in the shaft according to the rotation of the door; damping means which provides a damping function in order to delay the ascending speed of the piston in the case that the piston ascends according to closing of the door; and return means which provides a restoring force to the rotational/linear motion converter in order to return the door to an initial position at the time when the door is closed. [Claim 2]

The automatic return hinge apparatus according to claim 1, wherein the rotational/linear motion converting means comprises: a guide hole forming portion which has first and second vertical guide holes which are installed in the inner circumferential surface of the central body and face each other in the vertical direction; a camshaft which includes a cylindrical portion in which first and second elevating guide holes which are extended from the shaft and are made of a spiral shape of a movement symmetrical structure for each other along the outer circumferential surface thereof, are penetratively formed and which is pivoted by a relative external force which is applied to the upper body when the door is rotated; and a guide pin whose both end portions are combined with the first and second vertical guide holes via the first and second elevating guide holes, respectively, in which one end of the guide pin is connected to the upper portion of the piston rod. [Claim 31

The automatic return hinge apparatus according to claim 2, wherein the first and second elevating guide holes comprise a first elevating section formed of a first cam diagram angle, a second elevating section formed of a second cam diagram angle which is relatively smaller than the first cam diagram angle, and a stop section whose cam diagram angle is zero, respectively. [Claim 4]

The automatic return hinge apparatus according to claim 2, wherein the damping means comprises: a piston rod which includes a first oil path whose leading end is connected to the guide pin so as to be slidably combined with the inner portion of the cylindrical portion of the camshaft and whose lower end is connected to the center of the piston, so that the oil can flow between the upper and lower chambers," at least one check valve which is installed in the piston and opens the oil path of the oil moving from the lower chamber to the upper chamber at the opening time of the door, and closes the oil path of the oil moving from the upper chamber to the lower chamber at the door closing time; and an elevating speed control unit for controlling the elevating speed of the piston which ascends and descends at the door closing time. [Claim 5]

The automatic return hinge apparatus according to claim 4, wherein the elevating speed control unit comprises a fluid pressure control rod whose leading end is inserted into the first oil path of the piston rod and which controls an amount of oil flowing from the upper chamber to the lower chamber through the first oil path. [Claim 6]

The automatic return hinge apparatus according to claim 5, wherein the fluid pressure control rod includes a high-speed setting portion and a low-speed setting portion in order to vary the amount of oil flowing through the first oil path according to the opening angle of the door. [Claim 7]

The automatic return hinge apparatus according to claim 5, wherein the high-speed setting portion of the fluid pressure control rod is formed of an identical diameter and the low-speed setting portion is tapered so that the diameter of the low-speed setting portion is gradually reduced towards the leading end portion. [Claim 8]

The automatic return hinge apparatus according to claim 5, wherein the fluid pressure control rod includes a low-speed setting portion which is tapered so that diameter of the low-speed setting portion is gradually reduced towards the leading end portion. [Claim 9]

The automatic return hinge apparatus according to claim 1, wherein the damping means includes at least one check valve which is installed in at least one oil path of the piston and which opens the oil path of the oil moving from the lower chamber to the upper chamber, and limits the oil path of the oil moving from the upper chamber to the lower chamber to have a relatively small amount of oil in order to provide a uniform damping power at the door closing time. [Claim 10]

The automatic return hinge apparatus according to claim 1, wherein the return means comprises: a torsion spring providing a restoring force for rotating the shaft in the direction returning the door at the door closing time, and which is built in the upper body so that one end of the torsion spring is fixed to the upper end portion of the shaft; and a clutch unit which is connected to the other end of the torsion spring to thus stop an increment of an elastic force by an reverse twisting of the torsion spring when it reaches a clutching starting angle at the door opening time, and restore a restoring force of the torsion spring when reaching the clutching starting angle at the door closing time. [Claim 11]

The automatic return hinge apparatus according to claim 10, wherein the clutch unit comprises: an outer clutch whose outer circumference is fixed to the inner circumference of the central body in a forced insert structure; an inner clutch whose lower end is rotatably inserted into the upper end of the outer clutch, in the internal space of which the shaft is supported at a rotatable contact state, and to the upper end of which the lower end portion of the torsion spring is fixed; and a pair of roller balls which are disposed between the outer and inner clutches and play the role of combining the inner clutch with the shaft or separating the former from the latter according to the opening angle of the door. [Claim 12]

The automatic return hinge apparatus according to claim 10, further comprising a return spring which is installed in the lower chamber and which is compressed at the door opening time, and providing a restoring force for ascending the piston at the closing time of the door. [Claim 131

A hinge apparatus having an automatic return function for a door which has first and second hinges which are respectively fixed to the door and a door frame, the automatic return hinge apparatus comprising: an upper body on a circumferential surface of which the upper side of the first hinge is integrally formed and whose upper end portion is blocked by an upper cap on the inner side surface of which a recess is formed; a lower body on a circumferential surface of which the lower side of the first hinge is integrally formed and whose lower end portion is blocked by a lower cap which is connected in a sealing manner! a central body on a circumferential surface of which one side of the second hinge is integrally formed and which is pivotally arranged between the upper and lower bodies; a shaft whose lower end portion is rotatably installed in the middle portion of the central body and whose upper end portion is inserted into the recess of the upper cap and is fixed to the upper body; an isolation unit for dividing the chamber where the oil is filled in the central body into first and second chambers; first and second pistons whose outer circumferences are slidably installed along the inner circumferential surface of the first and second chambers in the central body and which divides the inner portions of the first and second chambers into upper and lower chambers, respectively; rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the first and second pistons when the rotational force of the door is applied in the shaft according to the rotation of the door; first and second damping means which provide a damping function in order to delay the ascending speeds of the first and second pistons in the case that the first and second pistons ascend according to closing of the door; and return means which provides a restoring force to the rotational/linear motion converter in order to return the door to an initial position at the time when the door is closed. [Claim 14]

The automatic return hinge apparatus according to claim 13, wherein the damping means each comprise: a piston rod which includes a first oil path whose lower end is connected to the centers of the first and second pistons, so that the first and second pistons are exercised up and down according to operation of the rotational/linear motion converter and so that the oil can flow between the upper and lower chambers of the first and second chambers, respectively! at least one check valve which is respectively installed in the first and second pistons and opens the oil path of the oil moving from the lower chamber to the upper chamber at the opening time of the door, and closes the oil path of the oil moving from the upper chamber to the lower chamber at the door closing time; and an elevating speed control unit for controlling the elevating speeds of the first and second pistons which ascends and descends at the door closing time. [Claim 151

The automatic return hinge apparatus according to claim 14, wherein the elevating speed control unit comprises a fluid pressure control rod in which a high-speed setting portion and a low-speed setting portion are repeatedly formed in order to vary the amount of oil flowing through the first oil path according to the opening angle of the door. [Claim 16]

The automatic return hinge apparatus according to claim 14, wherein the first and second check valves further include first and second overpressure preventive units for terminating overpressure in the case that the first and second pistons are required to rise up by external forces at a high speed and thus the upper chamber is increased to a predetermined pressure or higher.

[Claim 17] The automatic return hinge apparatus according to claim 13, wherein the return means comprises: a torsion spring providing a restoring force for rotating the shaft in the direction returning the door at the door closing time, and which is built in the upper body so that one end of the torsion spring is fixed to the upper end portion of the shaft; and a clutch unit which is connected to the other end of the torsion spring to thus stop an increment of an elastic force by an reverse twisting of the torsion spring when it reaches a clutching starting angle at the door opening time, and restore a restoring force of the torsion spring when reaching the clutching starting angle at the door closing time. [Claim 18]

The automatic return hinge apparatus according to claim 17, further comprising a return spring which is installed in the lower chamber of the second chamber, and which is compressed at the door opening time, and providing a restoring force for ascending the piston at the closing time of the door. [Claim 19]

The automatic return hinge apparatus according to claim 13, wherein the first damping means comprises at least one first check valve which is installed in the first piston and opens the oil path of the oil moving from the lower chamber to the upper chamber at the opening time of the door, and limits the oil path of the oil moving from the upper chamber to the lower chamber to have a relatively small amount of oil in order to provide a uniform damping power at the door closing time, and wherein the second damping means comprises at least one second check valve which is installed in the second piston and opens the oil path of the oil moving from the lower chamber to the upper chamber at the opening time of the door, and blocks the oil path of the oil moving from the upper chamber to the lower chamber at the closing time of the door. [Claim 20]

A hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising: an upper body on a circumferential surface of which the upper side of a first hinge which is fixed to a door is integrally formed and whose upper end portion is blocked by an upper cap; a lower body on a circumferential surface of which the lower side of the first hinge is integrally formed and whose lower end portion is blocked by a lower cap which is connected in a sealing manner; a central body on a circumferential surface of which one side of a second hinge which is fixed to a door frame is integrally formed and which is pivotally arranged between the upper and lower bodies, in which a sealing cap is combined in the lower end portion of the central body; a shaft whose one end is fixed to the upper cap and whose other end is extended to the central body; a piston whose outer circumference is slidably installed along the inner circumferential surface of the central body and which divides the inner portion of the central body into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the piston when the rotational force of the door is applied in the shaft according to the opening and closing of the door; damping means which is installed in the piston, for controlling the descending and ascending speeds of the piston according to the operation of the opening and closing of the door and selectively providing a damping function in the case that the piston ascends; a return spring which is installed in the lower chamber, and is compressed at the opening time of the door and provides a restoring force for ascending the piston at the closing time of the door; a torsion spring which is built in the upper portion of the central body so that one end of the torsion spring is fixed to the upper end portion of the shaft thereby providing a restoring force rotating the shaft in the direction closing the door; and a clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is within the range of the predetermined opening angle. [Claim 21]

The automatic return hinge apparatus according to claim 20, wherein the rotational/linear motion converting means comprises: a guide hole forming portion which has first and second vertical guide holes which are installed in the inner circumferential surface of the central body and face each other in the vertical direction; a camshaft which includes a cylindrical portion in which first and second elevating guide holes which are extended from the shaft and are made of a spiral shape of a movement symmetrical structure for each other along the outer circumferential surface thereof, are penetratively formed and which is pivoted by a relative external force which is applied to the upper body when the door is rotated; and a guide pin whose both end portions are combined with the first and second vertical guide holes via the first and second elevating guide holes, respectively, in which one end of the guide pin is connected to the upper portion of the piston rod, wherein the clutch unit comprises-' an outer clutch whose outer circumference is fixed to the inner circumference of the central body in a forced insert structure; an inner clutch whose lower end is rotatably inserted into the upper end of the outer clutch, in the internal space of which the shaft is supported at a rotatable contact state, and to the upper end of which the lower end portion of the torsion spring is fixed; and a pair of roller balls which are disposed between the outer and inner clutches and play the role of combining the inner clutch with the shaft or separating the former from the latter according to the opening angle of the door, and wherein the outer clutch and the guide hole forming portion are integrally formed. [Claim 22] A hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising: a body formed of a single cylindrical shape and whose upper end portion is blocked by an upper cap and whose lower end portion is blocked by a lower cap which is connected in a sealing manner; a shaft whose one end is extended to the outside via the upper cap, and whose other end is extended to the body; a piston whose outer circumference is slidably installed along the inner circumferential surface of the body and which divides the inner portion of the body into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the shaft into an axial linear motion of the piston when the rotational force of the door is applied in the shaft according to the opening and closing of the door; damping means which is installed in the piston, for controlling the ascending speeds of the piston at the closing of the door; a return spring which is installed in the lower chamber, and is compressed at the opening time of the door and provides a restoring force for ascending the piston at the closing time of the door; a torsion spring which is built in the upper portion of the body so that one end of the torsion spring is fixed to the upper cap, thereby providing a restoring force rotating the shaft in the direction closing the door; and a clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is in the range of the predetermined opening angle. [Claim 23]

The automatic return hinge apparatus according to claim 22, further comprising: a first fixing member whose one end is combined with the upper cap and whose other end is combined with the door; and a second fixing member whose one end is combined with the exposed shaft and whose other end is combined with a door frame. [Claim 241

The automatic return hinge apparatus according to claim 22, wherein the body is embedded in the door.

[Claim 25] The automatic return hinge apparatus according to claim 22, wherein the body comprises a first body portion including the torsion spring and the clutch unit; and a second body portion includising the piston, the rotational/linear motion converting means, the damping means, and the return spring. [Claim 26]

The automatic return hinge apparatus according to claim 25, wherein the first and second body portions are embedded in the lower and upper portions of the door, respectively, and first and second shafts which are extended from the first and second body portions are fixed to the lower and upper portions of the door frame, respectively. [Claim 27]

A hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising: first and second hinge apparatus units which are embedded in the lower and upper portions of a door, respectively, wherein the first hinge apparatus unit comprises: a first body whose upper and lower end portions are blocked by first upper and lower caps, respectively; a first shaft whose one end is extended to the outside via the first upper cap and whose other end is extended to the inner portion of the first body! a torsion spring which is built in the upper portion of the body so that one end of the torsion spring is fixed to the first upper cap, thereby providing a restoring force rotating the first shaft in the direction closing the door; and a clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is within the range of the predetermined opening angle, and wherein the second hinge apparatus unit comprises: a second body whose upper and portion is blocked by a second upper cap, and whose lower end portion is blocked by a second lower cap in a sealing manner; a second shaft whose one end is extended to the outside via the second upper cap and whose other end is extended to the inner portion of the second body; an isolation unit which divides the chamber of the second body into first and second chambers; first and second pistons whose outer circumferences are slidably installed along the inner circumferential surfaces of the first and second chambers in the second body and which divide the inner portions of the first and second chambers into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the second shaft into axial linear motions of the first and second pistons when the rotational force of the door is applied in the second shaft according to the rotation of the door; and first and second damping means which provide damping functions so that the ascending speeds of the first and second pistons can be delayed in the case that the first and second pistons ascend at the closing time of the door. [Claim 28]

The automatic return hinge apparatus according to claim 27, wherein the clutch unit comprises: an outer clutch whose outer circumference is fixed to the inner circumference of the first body in a forced insert structure; an inner clutch whose lower end is rotatably inserted into the upper end of the outer clutch, in the internal space of which the first shaft is supported at a rotatable contact state, and to the upper end of which the lower end portion of the torsion spring is fixed; and a pair of roller balls which are disposed between the outer and inner clutches and play the role of combining the inner clutch with the first shaft or separating the former from the latter according to the opening angle of the door. [Claim 29]

The automatic return hinge apparatus according to claim 27, further comprising a return spring which is installed in the lower chamber of the second chamber, and is compressed at the opening time of the door and provides a restoring force for ascending the second piston at the closing time of the door. [Claim 30]

A hinge apparatus having an automatic return function, the automatic return hinge apparatus comprising: first and second hinge apparatus units which are embedded in the lower and upper portions of a door, respectively, wherein the first hinge apparatus unit comprises-' a first body whose upper and lower end portions are blocked by first upper and lower caps, respectively; a first shaft whose one end is extended to the outside via the first upper cap and whose other end is extended to the inner portion of the first body,' a torsion spring whose one end is fixed to the first lower cap, thereby providing a restoring force rotating the first shaft in the direction closing the door; and a ball-type clutch unit which is connected with the torsion spring, for stopping an increment of an elastic force of the torsion spring in the case that an opening angle exceeds a predetermined opening angle at the door opening and closing times, and for restoring the elastic force of the torsion spring in the case that the opening angle is within the range of the predetermined opening angle, and wherein the second hinge apparatus unit comprises: a second body whose upper and portion is blocked by a second upper cap, and whose lower end portion is blocked by a second lower cap in a sealing manner; a second shaft whose one end is extended to the outside via the second upper cap and whose other end is extended to the inner portion of the second body; an isolation unit which divides the chamber of the second body into first and second chambers; first and second pistons whose outer circumferences are slidably installed along the inner circumferential surfaces of the first and second chambers in the second body and which divide the inner portions of the first and second chambers into upper and lower chambers; rotational/linear motion converting means which converts a rotational motion of the second shaft into axial linear motions of the first and second pistons when the rotational force of the door is applied in the second shaft according to the rotation of the door; and first and second damping means which provide damping functions so that the ascending speeds of the first and second pistons can be delayed in the case that the first and second pistons ascend at the closing time of the door.

[Claim 31]

The automatic return hinge apparatus according to claim 30, wherein the ball-type clutch unit comprises : the first upper cap having a throughhole at the central portion thereof; an axial disc in which the first shaft is combined with the throughhole and which is disposed perpendicularly with the first shaft and in opposition to the upper cap; a body holder which is disposed in opposition to the lower portion of the axial disc and is fixed in the door, in which the first shaft is rotatably inserted into the throughhole of the central portion thereof; and first and second balls which are selectively combined with each other to thereby deliver the rotational force, and thus remove a compression repulsive power of the torsion spring whose one end is combined in the body holder, while moving between the upper cap and the axial disc and the body holder, when the body holder is rotated in one direction and the other direction. [Claim 32]

The automatic return hinge apparatus according to claim 30, wherein the first and second shafts in the first and second hinge apparatus units are combined with each other in a simple axial coupling structure and the first and second bodies are integrally formed. [Claim 33]

The automatic return hinge apparatus according to claim 30, further comprising a return spring which is installed in the lower chamber of the second chamber, and is compressed at the opening time of the door and provides a restoring force for ascending the second piston at the closing time of the door.