Description ROTATION TYPE OIL DAMPER

Technical Field

[1] The present invention relates to a damper, and more particularly, to a rotary-type oil damper that can damp a rotating force, which is generated when a door and a cover or lid are opened and closed, by using a blade rotating along a rotation axis and a flow resistance of a viscous fluid. Background Art

[2] Generally, in a process of opening and closing a door, a cover, a lid, and so on, a rotary-type damper is used in order to prevent the door or lid to be closed abruptly by controlling its rotating force. The related art rotary-type damper broadly includes an elastic member type damper, which uses an elastic member such as a spring, and a viscous fluid type damper, which uses a viscous fluid to provide a damping force.

[3] Among the two types, in the elastic member type, the damping force is generated with respect to both a clockwise direction and a counter-clockwise direction. Therefore, when the damping force is required in only one of the two directions, the elastic member type damper cannot be adopted. Also, as the usage of the damper becomes more frequent, the elasticity of the elastic member deteriorates, thereby becoming unable to maintain a constant damping force.

[4] Meanwhile, in the rotary-type oil damper using the viscous fluid, the inside of a housing is filled with viscous fluid. And, a blade rotating within the housing is operated while being closely pressed to an inner peripheral surface of the housing. Also, a fluid flow path allowing the viscous fluid to pass through is formed on the blade, thereby generating the damping force from the flow resistance of the viscous fluid.

Disclosure of Invention Technical Problem

[5] Such related art rotary-type oil damper is disclosed in the Korean Patent Application

No. 414520 or in the Korean Utility Model No. 422594. However, the related art rotary-type oil damper has the following disadvantages.

[6] First of all, depending upon the object of application, in response to the rotating force that rotates a door, the oil damper requires the damping force to be adjusted (or regulated). However, the related art rotary-type oil damper is disadvantageous in that such control of the damping force is impossible. This is because the resistance applied to the blade formed inside the housing of the oil damper is equal to the resistance generated by the viscous fluid regardless of the rotating force and the rotating degree.

[7] Also, in the related art oil damper, a plurality of assembly parts is formed inside the housing in order to generate the damping force from airtight sealing and rotation of the viscous fluid. Thus, the structure becomes complicated, and the assembly process also becomes complicated, thereby causing a decrease in productivity. Additionally, the fabrication cost increases due to this complicated structure, and the growth in the overall size of the oil damper leads to limitations in applying the oil damper in various fields of technology.

[8] Moreover, the related art oil damper could not provide a completely airtight structure inside the housing. Therefore, the viscous fluid within the housing leaked to the outside, thereby causing a gradual deterioration in the damping force with respect to the frequent usage of the oil damper. In addition, the leakage of the viscous fluid also caused the surroundings of the oil damper to be unclean.

[9] Furthermore, in the related art oil damper, the fluid flow path, through which the viscous fluid flows, is asymmetrically formed along the axial direction of the housing, which eventually leads to a concentration of the damping force in a particular area only, thereby causing the oil damper to have an unstable structure. More specifically, since the generation of the damping force is concentrated near the fluid flow path, the rotating structure of the valve, which rotates (or turns) around an axis, becomes unstable. Technical Solution

[10] In an aspect of the present invention, a rotary-type oil damper includes a blade positioned in an airtight space, the airtight space being filled with a viscous fluid, a rotation axis being connected to an object for damping a rotating force and rotating the blade, a first flow path being formed on the rotation axis so as to allow the viscous fluid to pass through, based upon rotating movements of the rotating axis, and an operating valve being positioned to block the first flow path and being moved by an oil pressure of the viscous fluid, the viscous fluid being introduced to the first flow path when the rotation axis is forcibly rotated.

[11] In the oil damper according to an embodiment of the present invention, the first flow path may be formed inwards from an outer peripheral surface and may be bent downwards so as to be connected with the airtight space through a lower end of the rotation axis.

[12] In the oil damper according to an embodiment of the present invention, the operating valve may be positioned on the bent portion of the first flow path, so as to move along a longitudinal direction of the rotation axis.

[13] In the oil damper according to an embodiment of the present invention, the operating valve may include a wing enabling the operating valve to move easily by the oil

pressure of the viscous fluid, wherein the wing may be extended in all directions from an outer peripheral surface of the operating valve and may be positioned near a ceiling of the first flow path.

[14] The oil damper according to an embodiment of the present invention may further include a stopper extending from an inner wall of the airtight space to an outer peripheral surface of the rotation axis, so as to divide the airtight space into a plurality of unit spaces along with the blade, thereby limiting a rotating angle of the blade.

[15] In the oil damper according to an embodiment of the present invention, the blade and the stopper may each be formed in pairs and positioned to face into one another.

[16] The oil damper according to an embodiment of the present invention may further include a second flow path being formed at a predetermined length on a lower circumference of the rotation axis and connecting the spaces divided only in a predetermined angle range to which the rotation axis rotates.

[17] The oil damper according to an embodiment of the present invention may further include a hollow groove formed on the lower end of the rotation axis, a supporting protrusion protruding from a bottom surface of the airtight space so as to be fitted into the groove, and an upper end of the supporting protrusion being spaced apart from a ceiling of the groove, and a third flow path being formed to cross over the supporting protrusion and position to face into an end portion of the first flow path, the first flow path being formed on a lower end of the rotation axis within a predetermined angle range.

[18] In the oil damper according to an embodiment of the present invention, the operating valve may be lifted by an oil pressure of the viscous fluid, the viscous fluid passing through the first flow path, and may be positioned so as to return to its initial position by using its empty weight.

[19] The oil damper according to an embodiment of the present invention may further include an elastic member being installed in the rotation axis, so as to elastically push the operating valve.

[20] The oil damper according to an embodiment of the present invention may further include a via hole passing through the rotation axis in a longitudinal direction so as to connect the airtight space with the outside, and having the operating valve positioned therein, and a fixing member being fit around the via hole so as to seal the via hole.

[21] The oil damper according to an embodiment of the present invention may further include an elastic member being inserted in the via hole, so as to be positioned between the operating valve and the fixing member, thereby applying pressure on the regulating member.

[22] In the oil damper according to an embodiment of the present invention, the fixing member may be connected to the via hole by being screwed to the via hole, thereby

being capable of regulating an applied pressure of the elastic member.

Advantageous Effects

[23] The rotary-type oil damper according to the present invention having the above- described structure has the following effects.

[24] Firstly, in the rotary-type oil damper according to the present invention, an operating valve, which opens and closes a first flow path while moving in accordance with a corresponding oil pressure, is mounted on the first flow path having a viscous fluid pass therethrough. Therefore, when the rotating force of the object for damping a rotating force is larger than usual (i.e., when a user forcibly rotates the object for damping a rotating force, such as a door), the operating valve opens the flow path. Accordingly, when the oil damper according to the present invention is applied to a door, the door is adequately damped so as to be opened, only when the user closes or opens the door. And, when the user does not apply any force, the rotation of the door is stopped. Therefore, according to the present invention, not only can minor or casual accidents, which happen when the door is shut abruptly, be prevented in advance but the door can also remain open at a predetermined angle.

[25] Secondly, a second flow path, which is provided at a predetermined length on a lower circumference of the rotation axis, connects the spaces divided only in a predetermined angle range to which the rotation axis rotates. Also, a third flow path formed on the supporting protrusion is positioned to face into an end portion of the first flow path, which is formed on the lower end of the rotation axis within a predetermined angle range defined by the rotation of the rotation axis. Accordingly, when the rotation axis is within the predetermined angle range, the viscous fluid moves by passing through the second flow path and the third flow path, thereby decreasing the damping force of the oil damper. Therefore, according to the present invention, when the object for damping the rotating force, such as a door, begins to open, the damping force is small at first. However, as the rotation progresses, a damping force level of the oil damper may be controlled with respect to the object of application, so that the damping force can become larger.

[26] Thirdly, according to the present invention, by optimizing a rotation axis structure, which is mounted in the housing and generates a damping force by sealing the space accommodating the viscous fluid and by using the blades and the flow paths, the structure can be simplified and the number of assembly parts can be minimized, thereby enhancing productivity.

[27] Fourthly, according to the present invention, by preventing the viscous fluid from leaking to the outer side of the oil damper, the deterioration of the damping performance caused by frequent usage can be prevented, thereby maintaining a stable

damping performance. Additionally, by preventing the leakage of the viscous fluid, the surroundings of the oil damper may be prevented from becoming unclean and dirty by the viscous fluid, thereby maintaining a level of cleanness in the oil damper.

[28] And, finally, by symmetrically designing the blades, the stoppers, and the flow path, the damping force generated from an airtight space, which accommodates the viscous fluid, can be prevented from being concentrated only in one specific area, thereby enabling the oil damper to be designed with stability. Brief Description of Drawings

[29] Fig. 1 illustrates a perspective view of a refrigerator having an oil damper according to an embodiment of the present invention applied thereto;

[30] Fig. 2 illustrates a disassembled perspective view of a structure of the oil damper according to the present invention being connected to a hinge axis of the refrigerator shown in Fig. 1 ;

[31] Fig. 3 illustrates a disassembled perspective view of the oil damper shown in Fig. 2;

[32] Fig. 4 illustrates a cross-sectional view taken along line I-I of Fig. 2;

[33] Fig. 5 illustrates a perspective cross-sectional view taken along line II-II of Fig. 2;

[34] Fig. 6 to Fig. 8 illustrate perspective cross-sectional views showing the rotation axis in normal rotation, when the oil damper of Fig. 2 is operated;

[35] Fig. 9 illustrates a cross-sectional view showing a movement of a viscous fluid passing through a first flow path, when a rotation axis of the oil damper shown in Fig. 2 rotates normally; and

[36] Fig. 10 illustrates a cross-sectional view showing a movement of a viscous fluid passing through a first flow path, when a rotation axis of the oil damper shown in Fig.

2 rotates inversely.

Best Mode for Carrying out the Invention

[37] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, in the description of the present invention, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and detailed description of the same will be omitted for simplicity.

[38] The rotary-type oil damper according to the present invention is extremely useful when applied to a structure having a door or lid lifted and rotated in order to be open or closed, such as a Kimchi refrigerator or a small commercial freezer (not shown). In Fig. 1, a refrigerator having an oil damper according to an embodiment of the present invention applied thereto is illustrated, which will now be described in more detail with reference to the drawing.

[39] In a food preserving device, such as a Kimchi refrigerator or a small freezer for

freezing and storing frozen goods, the inside of a main body 10 is provided with a divided storage compartment 20, as shown in Fig. 1. Herein, cool air generated by a freezing cycle is provided to the storage compartment 20. In order to so, although it is not shown in the drawing, the main body 10 is provided with a plurality of general assembly parts including a compressor, a condensor, and a vaporizer, which collectively configure the freezing cycle, and also a refrigerant tube connecting the compressor, condensor, and vaporizer, and a refrigerant filling the refrigerant tube, so as to be circulated. The refrigerant is vaporized by the vaporizer, thereby absorbing the surrounding heat. Thereafter, the cooled air surrounding the vaporizer is provided to the inside of the storage compartment (not shown). Thus, the food stored in the storage compartment 20 can be freshly preserved for a long period of time in a refrigerated or frozen state.

[40] As shown in Fig. 1, a Kimchi refrigerator or a small freezer for freezing and storing frozen goods generally adopts a structure of opening a door 30 by lifting the door 30 upwards, as shown in Fig. 1. Accordingly, an upper portion of the storage compartment 20 is open, and the door 30 is joined (or coupled) with an upper side of the main body 10 by a hinge, so that the upper portion of the storage compartment 20 can be open or closed. Herein, the undescribed part with the reference numeral 40 corresponds to a control panel.

[41] As shown in Fig. 2, a hinge axis 31 is protruded from one end of the door 30, and a coupling protrusion 35 having a predetermined shape is protruded from an end portion of the hinge axis 31. The oil damper 100 according to an embodiment of the present invention is connected to the hinge axis 31. Herein, the oil damper 100 is mounted to the main body 10. The oil damper 100 uses a fluid flow resistance of the viscous fluid, such as oil, to damp the rotating force of the hinge axis 31, so as to prevent the door 30 from being shut (or closed) or open abruptly, thereby preventing minor or casual accidents or hinge damage caused by the impact. The structure of the oil damper 100 according to the embodiment of the present invention having such functions is illustrated in detail in Fig. 2 to Fig. 5. Hereinafter, the structure of the oil damper 100 according to the embodiment of the present invention will be described in detail with reference to the corresponding drawings.

[42] Herein, Fig. 2 illustrates a disassembled perspective view of a structure of the oil damper according to the present invention being connected to a hinge axis of the refrigerator shown in Fig. 1. Fig. 3 illustrates a disassembled perspective view of the oil damper shown in Fig. 2. Fig. 4 illustrates a cross-sectional view taken along line I-I of Fig. 2. And, Fig. 5 illustrates a perspective cross-sectional view taken along line II- II of Fig. 2.

[43] As shown in Fig. 3 and Fig. 4, the housing 110 of the oil damper 100 has one open

side, in which an accommodation space is formed. The outer surface of the housing 110 has the shape similar to a rectangular parallelepiped (or a rectangular box), as shown in Fig. 1. However, the overall shape of the housing will not be limited only to the rectangular box-like figure and may vary depending upon the object that is to be mounted on the housing 110. The housing 110 may be fixed in a variety of methods in accordance with the mounting object. For example, the housing 110 may be inserted in and fixed to the mounting object, or, as shown in Fig. 1 to Fig. 3, the housing 110 may be stably fixed to the mounting object by using a flange 111 and a fastening element (not shown), which are formed on the outer surface of the housing 110 in order to be coupled with the mounting object. Herein, the flange 111 is provided with fastening apertures I l ia enabling the fastening element to pass through.

[44] The accommodation space is formed in a cylindrical shape, as shown in Fig. 4, wherein its lower part is blocked by the housing 110 and its upper part is open. A viscous fluid is filled in the lower part of the accommodation space within the housing 110. Additionally, a rotation axis 130, which is connected to an object for damping the rotating force, such as the door 30, and rotates, is placed in the accommodation space. Then, the open upper part of the accommodation space is covered by a cover 120.

[45] The cover 120 is coupled with the open upper portion of the housing 110. More specifically, a fastening hole 124 is formed in each corner portion of the cover 120, as shown in Fig. 2 to Fig. 4. And, a coupling hole 114 corresponding to each fastening hole 124 is formed in each upper corner portion of the housing 110. Then, a fastening element 126 is formed to pass through each fastening hole 124 and coupling hole 114, thereby enabling the cover 120 to be coupled with the housing 110. Thus, the housing 110 is covered.

[46] An opening 121 is formed in the center portion of the cover 120, as shown in Fig. 2 to Fig. 4. Herein, the hinge axis 31 of the door 30 is introduced inside the housing 110 by passing through the opening 121, so as to be connected with the rotation axis 130 provided inside the housing 110. Conversely, the rotation axis 130 may be exposed to the outside through the opening 121 and may be equipped so that the hinge axis 31 of the door 30 can be connected with the end portion of the exposed rotation axis 130.

[47] The rotation axis 130 is placed on the central axis of the accommodation space in a longitudinal direction. At the mid-portion of the rotation axis 130, a compartment 140 is protruded, as shown in Fig. 4, so as to form an airtight space A at the lower portion of the accommodation space, which is filled with the viscous fluid. Also, a lower portion of the rotation axis 130 placed in the airtight space A is provided with a blade 150, which is positioned to be submerged in the viscous fluid, thereby damping the rotating force of the corresponding object by rotating along the rotation axis 130 and using the flow resistance of the viscous fluid. Hereinafter, the rotation axis 130, the

compartment 140, and the blade 150 will be described in more detail with reference to the accompanying drawings.

[48] As shown in Fig. 3 and Fig. 4, the compartment 140 is placed at the mid-portion of the rotation axis 130. The compartment 140 is extended in all directions from the outer peripheral surface of the rotation axis 130 to the inner suface of the housing 110, thereby dividing the accommodation space into an upper portion and a lower portion. Accordingly, an airtight space A, which is surrounded by the compartment 140 and the bottom of the housing 110, is formed in the lower portion of the housing 110. The airtight space A formed as described above is then filled with a viscous fluid, i.e., oil.

[49] In order to enhance the airtight sealing force between the compartment 140 and the inner surface of the housing 110, a hollow (or concave) groove 141 is provided on the outer peripheral surface of the compartment 140, as shown in Fig. 3 and Fig. 4, and a ring-shaped sealing 145 is provided around the groove 141. The sealing 145 is in close contact with the outer peripheral surface of the compartment 140 and with the inner surface of the housing 110, thereby effectively preventing the oil filling the airtight space A from leaking.

[50] The rotation axis 130 is, for example, shaped like a long cylindrical bar and placed inside the accommodation space. The lower end of the rotation axis 130 is fixed to be in contact with the bottom of the housing 110, i.e., the bottom of the airtight space A. Since the compartment 140, which is extended from the mid-portion of the rotation axis 130, comes in contact with the inner surface of the housing 110, the rotation axis 130 stably placed in the center of the accommodation space within the housing 110 in the longitudinal direction, as shown in Fig. 4.

[51] A mounting groove 131 is formed on the upper end of the rotation axis 130, as shown in Fig. 4. Herein, the coupling protrusion 35 formed on the hinge axis 31 of the door 30 is fit into the mounting groove 131. Since the upper end of the rotation axis 130, which is placed so as to be connected with the outside through the opening 121, is connected to the door 30, the rotation axis 130 can rotate within the housing 110. While the rotation axis 130 rotates, a friction may be generated between the upper end of the rotation axis 130 and the cover 120. Therefore, as shown in Fig. 3 and Fig. 4, a washer 125 may be provided between the cover 120 and the upper end of the rotation axis 130.

[52] As shown in Fig. 4, a hollow groove 137 is formed on the lower end of the rotation axis 130, which comes in contact with the bottom of the airtight space A. A supporting protrusion 117 protrudes from the bottom of the airtight space A so as to be inserted in the groove 137. Accordingly, the rotation axis 130 can stably rotate along a pivot of the rotation axis 130 without shaking. Meanwhile, a gap is formed between the supporting protrusion 117 and the upper inner surface of the groove 137 formed on the

lower end of the rotation axis 130, as shown in Fig. 4. Herein, the gap is connected with a first flow path 101, which will be described later on.

[53] The blade 150 is placed below the compartment 140 and is extended from the lower outer peripheral surface of the rotation axis 130 towards the inner side wall of the airtight space A. As shown in Fig. 5, the blade 150 is in close contact with the inner side wall of the airtight space A, thereby dividing the airtight space A into a plurality of unit spaces.

[54] According to an embodiment of the present invention, the blade 150 is provided in pairs, as shown in Fig. 3 and Fig. 5, and placed symmetrically with respect to the rotation axis 130. As described above, by symmetrically placing the blades 150, the damping force may be prevented from being concentrated in only a specific area, thereby stabilizing the structure of the oil damper.

[55] As shown in Fig. 5, a stopper 115 is protruded from the inner side wall of the airtight space A. The stopper 115 is extended towards the rotation axis 130, so as to limit the rotating movements of the blade 150 when the rotation axis 130 is rotated. With the above-described structure, the rotation angle of the object for damping the rotating force, such as a door, a cover, or a lid, which is fixed to the oil damper 100 according to the present invention, may be limited.

[56] The stopper 115 may be formed to be extended to the outer peripheral surface of the rotation axis 130. Accordingly, by touching the outer peripheral surface of the rotation axis 130, the stopper 115 along with the blade 150 divides the airtight space A into a plurality of unit spaces. The stopper 115 having the above-described structure is also formed in pairs, just as the blades 150, which are arranged to symmetrically face into each other within the airtight space A.

[57] The oil damper 100 according to the embodiment of the present invention is provided with at least one flow path, which moves (or transports) viscous fluid accommodated in a space, which is divided by the blade 150 and the stopper 115 during the rotation of the rotation axis 130, into another space. The at least one flow path may be configured by including, for example, a first flow path 101, a first flow path 101, and a third flow path 103.

[58] In the flow paths provided as described above, an operating valve 165 is placed on the first flow path 101. Herein, the operating valve 165 is positioned to block the first flow path 101. Accordingly, when the rotation axis 130 forcibly rotates, i.e., when the user opens or closes the door 30, the operating valve 165 is moved by the oil pressure of the viscous fluid, which is introduced to the first flow path 101, thereby opening the first flow path 101. In addition, when a force is not applied to the rotation axis 130, i.e. , when the door 30 is not forcibly rotated, the first flow path 101 is blocked, thereby interrupting the flow of the viscous fluid through the first flow path 101. Hereinafter, the

first flow path 101, the operating valve 165, and each of the other flow paths having the above-described functions will now be described in detail with reference to the accompanying drawings.

[59] As shown in Fig. 4 and Fig.5, the first flow path 101 is formed on the rotation axis

130. The first flow path 101 is formed inwards from the outer peripheral surface of the rotation axis 130 and then bent downwards, so as to be connected with the airtight space A through the lower end of the rotation axis 130. Herein, an upper end of the first flow path 101 is positioned to be adjacent to (or in close contact with) a ceiling of inner upper surface (or ceiling) of the airtight space A, and a lower end of the first flow path 101 is formed on the lower end of the rotation axis 130 in a hollow shape. Herein, the lower end of the first flow path 101 is positioned to be adjacent to the side (or lateral) surface of the blade 150. The first flow path 101 having the above-described structure allows the viscous fluid to pass through, when the rotation axis 130 is forcibly rotated.

[60] The operating valve 165 is formed in the first flow path 101, as shown in Fig. 4, so as to block the first flow path 101. When the rotation axis is focibly rotated, the above- described operating valve 165 is moved by the oil pressure of the viscous fluid, which is introduced to the first flow path 101, thereby opening the first flow path 101. Such operating valve 165 may be positioned, for example, to fit in a via hole 135, which is formed to pass through the rotation axis 130, as shown in Fig. 4.

[61] The via hole 135 is formed to pass through the rotation axis 130 in a longitudinal direction, thereby connecting the first flow path 101 and the airtight space A with the outside. Herein, the viscous fluid may be introduced to the above-described via hole 135. In this case, when the viscous fluid is injected, the viscous fluid passes through the via hole 135 and the lower end of the first flow path 101, so as to be introduced to the airtight space A. Accordingly, the air inside the airtight space A is easily exhausted to the outside through the upper end of the first flow path 101 and the via hole 135.

[62] When the viscous fluid is completely introduced, the regulating valve 165 is inserted in the via hole 135, as shown in Fig. 4. Thereafter, a lower end of the operating valve 165 is formed to block the first flow path 101, which is formed in the rotation axis 130. Herein, as shown in Fig. 4, a bent section is formed on the first flow path 101, and the operating valve 165 is placed to open and close the bent section while moving along the longitudinal direction of the rotation axis 130.

[63] More specifically, the first flow path 101 is vertically extended upwards from a groove 137 formed at the lower end of the rotation axis 130, as shown in Fig. 4. Then, the first flow path 101 is bent towards the side wall, so as to be connected with the airtight space A. Thereafter, the regulating valve 165, which is inserted in the via hole 135, is placed to block the area vertically formed in the first flow path 101. Ac-

cordingly, the oil pressure causes the operating valve 165 to move vertically, i.e., to move along the longitudinal direction of the rotation axis 130, thereby opening and closing the first flow path 101.

[64] As shown in Fig. 3 and Fig. 4, a broad wing 167 is formed on the surface of the operating valve 165. The wing 167 is extended in all directions from the upper portion of the operating valve 165. Also, when the the operating valve 165 is positioned to block the first flow path 101, the wing 167 is inserted in the via hole 135, so as to be positioned near the ceiling (or inner upper surface) of the first flow path 101. Accordingly, when the oil pressure within the first flow path 101 is elevated, the viscous fluid pushes the wing 167 upwards. Thus, the operating valve 165 can be eaily moved by the oil pressure.

[65] The operating valve 165 may be positioned to block the first flow path 101 with its own weight (or empty weight). However, as shown in Fig. 3 and Fig. 4, the operating valve 165 may be elastically pressurized by an elastic member 163 so as to block the first flow path 101. In the former case, the operating valve 165, which is lifted (or elevated) by the oil pressure, returns to its initial position by its empty weight, so as to block the first flow path 101. In the latter case, as shown in Fig. 4, the elastic member 163 is inserted in the via hole 135 after the operating valve 165 is inserted. Herein, with its ability to recover elasticity, the elastic member 163 may return to its initial position.

[66] After the operating valve 165 and the elastic member 163 are inserted in the via hole

135, a fixing member 161 is fit around the via hole 135 so that the via hole 135 can be completely sealed. At this point, the elastic member 163 supports the lower end of the fixing member 161, thereby elastically pushing the operating valve 165 downwards. The operating valve 165 is screwed on the via hole 135. And, by tightly screwing (or tightening) or loosening the operating valve 165, the applied pressure of the elastic member 163 may be adjusted. Accordingly, the pressure of the viscous fluid that moves the operating valve 165 may also be adjusted, which signifies that the damping force of the oil damper 100 can be managed by adjusting the operating valve 165. Meanwhile, in order to completely seal the via hole 135, a sealing 162 is inserted between the fixing member 161 and the rotation axis 130, as shown in Fig. 3 and Fig. 4.

[67] The second flow path 102 is provided at a predetermined length on a lower circumference of the rotation axis 130, as shown in Fig. 3 and Fig. 5. The second flow path 102 is extended from a point in close contact with one side surface of any one blade 150 towards the other blade 150 at a predetermined length. The second flow path 102 is formed to be longer than the width of the stopper 115. Accordingly, when the rotation axis 130 rotates, the second flow path 102 connects the spaces divided by the

stopper 115 in a predetermined angle range to which the rotation axis rotates. Evidently, when the rotation axis 130 rotates at an angle outside of the predetermined angle range, the second flow path 102 cannot connect the spaces divided by the stopper 115.

[68] When the rotation axis 130 rotates, and when the second flow path 102 connects the spaces divided by the stopper 115, the viscous fluid passes through the second flow path 102, thereby causing the damping force of the oil damper 100 to become relatively weak (or small). Conversely, when the rotation axis 130 deviates from the predetermined angle range, the second flow path 102 is incapable of moving the viscous fluid. Thus, the damping force of the oil damper 100 is relatively increased. Therefore, the second flow path 102 causes the damping force of the oil damper 100 to vary with respect to the rotating angle of the rotation axis 130.

[69] Meanwhile, as shown in Fig. 4 and Fig. 5, the third flow path 103 is formed on the supporting protrusion 117, so that the third flow path 103 can flow across the supporting protrusion 117. When the rotation axis 130 rotates, as shown in Fig. 5 and Fig. 6, the third flow path 103 is connected with the lower end of the first flow path 101 within a predetermined angle range. Therefore, a large amount of the viscous fluid may pass through the third flow path 103, when the rotation axis 130 rotates within the angle range, wherein the third flow path 103 is connected with the first flow path 101. Thus, the damping force of the oil damper 100 becomes weaker.

[70] Hereinafter, the process of damping the rotation force performed by the oil damper

100 according to an embodiment of the present invention, when the oil damper 100 is being operated, will now be described in detail with reference to Fig. 6 to Fig. 10. Herein, Fig. 6 to Fig. 8 illustrate perspective cross-sectional views showing the rotation axis in normal rotation, when the oil damper of Fig. 2 is operated. Fig. 9 illustrates a cross-sectional view showing a movement of a viscous fluid passing through a first flow path, when a rotation axis of the oil damper shown in Fig. 2 rotates normally. And, Fig. 10 illustrates a cross-sectional view showing a movement of a viscous fluid passing through a first flow path, when a rotation axis of the oil damper shown in Fig. 2 rotates inversely. An example of the oil damper 100 according to the present invention being applied to a door 30 configured to be open and closed while rotating in vertical directions, as shown in Fig. 1. However, it is apparent that the application of the oil damper 100 according to the present invention will not be limited only to the door of a refrigerator.

[71] In the storage compartment of Fig. 1, when the door 30 is closed, the operating valve

165 of the oil damper 100 is placed in the position shown in Fig. 4, and the blade 150 and the rotation axis 130 are placed in the respective positions shown in Fig. 5. In such initial position, the operating valve 165 closes the first flow path 101. Also, the lower

end of the first flow path 101 is connected with the airtight space A. However, the upper end of the first flow path 101 is in contact with the side surface of the stopper 115, thereby being blocked. The third flow path 103 is connected with the lower end of the first flow path 101. And, accordingly, the spaces that are divided by the blade 150 and the rotation axis 130 are connected with one another by the lower end of the first flow path 101 and the third flow path 103.

[72] In the initial position, wherein the door 30 is closed, when the door 30 of Fig. 1 is slightly lifted upwards, the rotation axis 130 and the blade 150 rotate in a normal direction, as shown in Fig. 6. The viscous fluid accommodated in a space that is placed before the rotating direction of the blade 150 shifts to a space that is placed after the rotating direction through the lower end of the first flow path 101 and the third flow path 103. Also, when the blade 150 rotates slightly in the normal direction, the second flow path 102 connects the two spaces that are divided by the stopper 115, as shown in Fig. 6. Accordingly, the viscous fluid can flow through the second flow path 102 as well.

[73] When the rotation axis 130 rotates, as shown in Fig. 6, the space that is placed before the rotating direction of the blade 150 is compressed by the blade 150. Therefore, the viscous fluid accommodated herein is also introduced inside of the rotation axis 130 through the lower end of the first flow path 101. The viscous fluid introduced to the inside of the rotation axis 130 then flows upwards along the first flow path 101, as shown in Fig. 9, thereby lifting the operating valve 165. At this point, since the moving direction of the operating valve 165 is the same as the travelling (or moving) direction of the viscous fluid, the viscous fluid overcomes the force of the elastic member 163, thereby being capable of lifting the operating valve 165. When the operating valve 165 is lifted so as to open the first flow path 101, a large amount of viscous fluid pass through the first flow path 101, thereby facilitating the rotating movements of the rotation axis 130.

[74] As described above, when the door 30 begins to open from its initial closed state, the viscous fluid pass through the spaces divided by the first flow path 101 and the second flow path 102 and the third flow path 103. Accordingly, the damping force of the oil damper 100 at this point becomes very small (or weak). Therefore, the user is capable of lifting the door 30 upwards by using just a small amount of force.

[75] As the opening of the door 30 becomes larger, the rotation axis 130 rotates more repeatedly, thereby reaching the position shown in Fig. 7. Accordingly, the lower end of the first flow path 101, which is formed on the lower end of the rotation axis 130, and the third flow path 103 are not connected to each other, as shown in Fig. 7. Furthermore, since the second flow path 102 is also concealed by the stopper 115, the spaces divided by the stopper 115 cannot be connected to one another, either.

Therefore, when the door 30 is open at a predetermined angle or larger, the viscous fluid can only travel by passing through the first flow path 101.

[76] In the state shown in Fig. 7, the operating valve 165 opens the first flow path 101 only when the oil pressure of the viscous fluid passing through the first flow path 101 is greater than the force of the elastic member 163. Conversely, when the oil pressure is smaller than the force of the elastic member 163, the applied pressure of the elastic member 163 causes the first flow path 101 to be closed. This signifies that the first flow path 101 can be open so as to allow the rotation axis 130 to rotate, only when the door 30 is forcibly rotated by a force greater than the predetermined strength. Therefore, when the door 30 is not forcibly rotated, the operating valve 165 closes the first flow path 101. And, accordingly, since the viscous fluid cannot flow, the rotation axis 130 is unable to rotate and remains fixed. Thus, the door 30 can be fixed to be open at a predetermined angle, as shown in Fig. 1.

[77] Between the position of the rotation axis 130 shown in Fig. 7 and the position of the rotation axis 130 shown in Fig. 8, even if the rotation axis 130 is placed in any one of the positions, the rotation axis 130 remains fixed, as long as the door 30 is not forcibly rotated. Therefore, the present invention is advantageous in that the user can open the door 30 at a desired angle, thereby being able to take out the stored food from the storage compartment 20. Evidently, at this point, since the operating valve 165 closes the first flow path 101, the door 30 cannot be rotated in an inverse direction due to its empty weight. Therefore, the hinge can be effectively prevented from being damaged by a casual accident or impact.

[78] When the door 30 rotates to a maximum level, the blade 150 comes into contact with the stopper 115, as shown in Fig. 8. Then, the rotating movements of the rotation axis 130 is stopped by the stopper 115, and the door 30 can no longer be open. In a state where the door is open to a maximum level, the blade 150 is supported by the stopper 115, and the operating valve 165 closes the first flow path 101 and also coses both the second flow path 102 and the third flow path 103. Therefore, since the viscous fluid cannot move, the door 30 may stably maintain its completely open state.

[79] Meanwhile, in the state shown in Fig. 8 where the door 30 is completely open, when the door 30 is inversely rotated so as to be closed, the viscous fluid is introduced to the inside of the rotation axis 130 through the upper end of the first flow path 101, as shown in Fig. 10. The viscous fluid that is introduced to the inside of the rotation axis 130 moves (or flows) along the lateral direction. Then, as shown by the arrow of Fig. 10, the viscous fluid lifts the operating valve 165 to an actual vertical direction of the flowing direction of the viscous fluid. Accordingly, a relatively large force is required to lift up the operating valve 165. Therefore, with only the empty weight of the door 30, the operating valve 165 is lifted up, thereby causing difficulty in closing the door

30. And, the operating valve 165 opens only when the user forcibly and inversely rotates the door 30 so as to close it, thereby enabling the door 30 to be closed.

[80] When the door 30 inversely rotates more and more until the rotation axis 130 reaches a position between the positions shown in Fig. 6 and Fig. 5, the second flow path 102 connects the spaces divided by the stopper 115 to one another, and is also connected to the end portions of the third flow path 103 or the first flow path 101. Accordingly, the viscous fluid also flows through the second flow path 102 and the third flow path 103. Therefore, since the damping force of the oil damper 100 becomes weak, the door 30 can be closed more easily. Also, even if the first flow path 101 blocks the operating valve 165 because the user no longer rotates the door 30, the viscous fluid flows through the second flow path 102 and the third flow path 103. Therefore, in the last process step in which the door 30 closes, the door 30 gradually closes automatically.

[81] When the rotary-type oil damper according to the present invention is applied as described above, the oil pressure of the viscous fluid allows the operating valve 165 to move (or travel) so as to open and close the first flow path 101, thereby being able to freely stall the movement of the door 30 within the predetermined angle range and stopping the door 30. Thus, based upon the object of application, the convenience for the user may be enhanced. Also, in the rotary-type oil damper 100 according to the present invention, the damping force may be increased or decreased based upon the rotating angle of the rotation axis 130. Accordingly, since the present invention can be designed so that the damping force decreases when the door is first opened, the convenience for the user may further be enhanced.

[82] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.