Description of the Prior Art A door closer or a door check has been widely used with an entrance or a fireproof door of a business building and a normal residential building. An exemplary configuration of the conventional door closer is shown in Fig. 1.

A main body 200 of the door closer wherein a sealing is performed after working fluid is charged within the main body is provided with a piston 201 adapted to move in a direction allowing a door to be closed by a spring 202. A rack 203 is formed with a portion of the piston 201. A pinion 204 formed with one portion of a first arm 205a of a link 205 is engaged with the rack 203.

A passage way 207 having a check valve 206 is formed within the piston 201. A first return way 208 having a large diameter and a second return way 209 having a small diameter are formed through lateral portions of a movement way of the piston 201.

The main body 200 and the link 205 are fixed to the door and a door frame, respectively.

When the door is opened, the rotation of the pinion 204 causes the rack 203 to be moved left, allowing the piston 201 to be moved left against the spring 202.

When an external force exerted on the door is removed, the spring 201 returns to its initial position by the restoring force of the spring 202. During this time, the returning of the working fluid driven by the piston 201 is made through the first return way 208 and the second return way 209 until the lead portion of the piston 201 reaches the first return way 208. However, after the lead portion of the piston 201 passes the first return way 208, the working fluid is returned through only the second return way 209. Accordingly, the door is smoothly closed in a lowered closing speed, preventing a shock and the slam.

The door closer having the mechanism described above is mounted to the door 20 and the door frame 10 to work, as shown in Fig. 2.

The door 20 is hinged at a portion of the door frame 10 surrounding the door 20.

On the other hand, the main body 200 is mounted on the door 20, whereas the first arm 205a of the link 205 is mounted on the main body 200, the second arm 205b mounted on the door frame 10. The door closer is actuated by the rotation of the link 205 caused by the rotation of the door 20.

The first arm 205a is hinged with the second arm 205b. An adjust arm 205c is in screw engagement with the second link 205b, allowing an adjustment of an engagement length between the second arm 205b and the adjust arm 205c. The closing force can be adjusted by adjusting a length of the second arm 205b by using the adjusting arm 205c.

In the door closer described above, since the piston 201 is translated within the horizontally mounted main body through the rotation of the link 205, the main body 200 is long in length and the link 205 becomes bulky. As a result of this, they protrude from the door 20 and the door frame 10, degrading the appearance of the door 20.

For this reason, it is general to use an embedded type door closer which is embedded into a lower portion of the door frame as a door closer mounted on an entrance of the building.

However, this type of door closer has a shortcoming in that it is easily contaminated by alien material, e. g., generated during a cleaning. As a result, it suffers from corrosion and contamination so serious as to make it impossible to disassemble the door closer for repair and maintenance purpose.

Although an attempt to embed the door closer into an upper portion of the door has been made to prevent those problems, there's another problem in that an upper portion of the door frame 10 must be larger in size since the torque required to automatically close the door 20 is exceedingly big and a deformation of the door frame occurs.

Another attempt is to form a working fluid returning device with a supporting member between the door 20 and the door frame 10. However, this is not successful, since the mounting place is too narrow to generate the required torque.

Further, since a long link 205 is in an engagement using a hinge and a screw, repeated opening and closing action wears the hinge and causes the screw engagement to be loose, often deforming the link 205 and loosening the adjusting arm. Accordingly, the life time of the door closer becomes more reduced and the reliability of the performance is not guaranteed.

Further, these types of door closers require a number of workers in installing the door closer due to numerous installing steps and have an increased manufacturing costs due to a plurality of components.

On the other hand, the door 20 equipped with the door closer described above can be automatically closed. Further, it can be momentarily maintained in an opened state for an entrance and exit purpose or ventilation. As for the fireproof door, it can be automatically closed when the fire breaks out, while maintaining an opened state in an ordinary condition.

For this reason, in order to prevent a state wherein supporting members 11 and 21 shown in Fig. 3 and fixed to the door frame 10 and the door 20, respectively do not latch with respect to each other, a stopper (not shown) of a shape of a hoof of a roe is mounted to a lower portion of the door 20 and is operated in such a manner that it is unfolded to fix the door 20 with respect to the ground to maintain the opened state of the door 20, while being folded up to close the door.

However, this manner is cumbersome to use.

Further, this type of stopper can not be used to the fireproof door, since the fireproof door must be automatically closed, when the fire breaks out. Therefore, a device capable of fixing the door 20 for ordinary entrance and exit and of automatically closing the door 20 when the fire breaks out is needed.

A prior art door closer for use with the fireproof door is shown in Fig. 4. A fixing plate 211 of a disk shape having a plurality of fixing holes 212 is fixed to a main body 200 of a cylindrical or a rectangular shape, between the main body 200 and the link 205. A stopper 213 is fixed along a circumference defined by the fixing holes 212. The stopper 213 is formed by fixing a plate spring 216 having a concave groove on a meltable metal 214. A roller 217 is formed on a lower portion of the link 205 to be engaged into one of the fixing holes 212 to maintain the opened state of the door 20 at a desired angle, or to be engaged with the concave groove of the plate spring 216 to maintain the door 20 in a fully opened state.

A material meltable at the break-out of the fire such as lead, tin, and bismuth can be used as the meltable metal 214. Accordingly, the plate spring 216 is released to be resiliently unfolded to cause the link 205 to be unlocked, allowing the door 20 to be automatically closed by the door closer.

However, the door closer described and shown in Fig. 4 is not widely used due to a exceedingly high price.

Summarv of the Invention It is, therefore, a primary object of the invention to provide a hydraulic cylinder fixed to a portion of a hinge of a door at which the door is combined to a door frame to thereby cause the door to be quickly opened and to be slowly closed by the hydraulic pressure.

The above and other objects of the invention are accomplished by providing a vertical type door closer connected to a door and a door frame using a hinge comprising: a first support member whose one end is connected to one of the door and the door frame ; a second support member connected at one end to the other of the door and the door frame, being hinged at the other end to the first support member ; a cylinder connected to one of the first support member and the second support member and containing working fluid therewithin, the cylinder having a pair of grooves opposite to each other at a center portion of an internal surface, forming a space opened upwardly, wherein the cylinder includes a vertically movable body having a pair of guiding protrusions formed on its external surface for allowing the vertically movable body to be movable along a guiding groove of the cylinder and a screw formed at its internal surface, a fixed shaft whose one end is fixed to one of the first support member and the second support member, while the other end having a screw engaged with the screw of the vertically movable body, a piston positioned under the vertically movable body and partitioning the internal space of the cylinder into an upper and a lower spaces, an oil passage formed on an inner wall of the cylinder to make the upper and the lower spaces to communicate with each other, a check valve for allowing an oil received in the lower space of the piston to be flown to the upper space in a unidirectional manner, a pressure control valve formed with a portion of the cylinder to control a pressure by the oil within the oil passage, and a restoring spring mounted in the lower space of the cylinder to provide the rotated door with a restoring force.

In accordance with another feature of the present invention, vertical type door closer automatically closing a door connected to a door frame by using a hinge comprising: a first support member whose one end is connected to one of the door and the door frame; a second support member connected at one end to the other of the door and the door frame, connected at the other end to the first support member; a cylinder connected to the second support member, containing working fluid therewithin, wherein the cylinder including a pair of grooves opposite to each other at a center portion of an internal surface and forms a space opened upwardly, a

vertically movable body having a pair of guiding protrusions formed on its external surface for allowing the vertically movable body to be movable along a guiding groove of the cylinder and a screw formed at its internal surface, a fixed shaft whose one end is fixed to the first support member, while the other end having a screw engaged with the screw of the vertically movable body, a piston positioned under the vertically movable body and partitioning the internal space of the cylinder into an upper and a lower spaces, an oil passage formed on an inner wall of the cylinder to make the upper and the lower spaces to communicate with each other, a check valve for allowing an oil received in the upper space of the piston to be flown to the lower space in a unidirectional manner, a pressure control valve formed with a portion of the cylinder to control a pressure by the oil within the oil passage, and a torsion spring for providing the door with a restoring force by resiliently combining the fixed shaft with the cylinder.

Brief Description of the Drawings The above and other objects and features of the instant invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which: Fig. 1 illustrates a schematic sectional view of a prior art door closer; Fig. 2 offers a schematic view of a door equipped with the door closer shown in Fig. 1; Fig. 3 shows an exploded perspective view of a hinge of the door; Fig. 4 shows a schematic perspective view and a sectional view of a prior art door closer; Fig. 5 is a view showing an installation of a vertical type door closer in accordance with the present invention; Fig. 6 offers a sectional view of a cylinder shown in Fig. 5; Fig. 7 depicts a perspective view of the important components shown in Fig. 6; Fig. 8 is a view showing another installation of the vertical type door closer in accordance with the present invention; Figs. 9a and 9b set forth an exploded perspective view and an assembled state view of important parts of the vertical type door closer in accordance with the present invention, respectively; Figs. 10a and 10b set forth an exploded perspective view and an assembled state view of

another important parts the vertical type door closer in accordance with the present invention, respectively; Figs. 1 la and 1 lob set forth an exploded perspective view and an assembled state view of another important parts the vertical type door closer in accordance with the present invention, respectively; Figs. 12a through 12c are planar views showing operations of the inventive vertical type door closer, respectively; Fig. 13 sets forth an exploded perspective view of another important parts the inventive vertical type door closer; Fig. 14 sets forth a sectional view of the inventive vertical type door closer; Fig. 15 is a planar view of the components shown in Fig. 14.

Figs. 16a through 16c are planar views showing operations of the inventive vertical type door closer, respectively; Fig. 17 is an exploded perspective view of the inventive vertical type door closer; Fig. 18 presents an assembled state view of the components shown in Fig. 17; Fig. 19 is a planar view showing operation of the inventive vertical type door closer; Fig. 20 is an enlarged planar view of the important parts shown in Fig. 19; Fig. 21 is an exploded perspective view of the inventive vertical type door closer; Fig. 22 is a sectional view of an embodiment of a roller sleeve of the inventive door closer; Figs. 23a through 23c are sectional views of another embodiment and operation of the roller sleeve of the inventive door closer, respectively; Fig. 24 offers a sectional view of a second embodiment of the inventive door closer; Fig. 25 depicts an exploded perspective view of important parts shown in Fig. 24; Fig. 26 shows a sectional view of a second embodiment of the inventive door closer; Fig. 27 shows a sectional view of a state wherein two features of the second embodiment of the inventive door closer shown in Figs. 24 and 25; Fig. 28 is a sectional view showing a basic feature of the inventive door closer; and Fig. 29 represents a sectional view of the inventive door closer shown in Fig. 28, when taken along a line V-V'.

Detailed Description of the Preferred Embodiments

Hereinbelow, preferred embodiments of the present invention are now described with reference to the accompanying drawings. First, a first embodiment of the present invention will be described with reference to Figs. 5 through 23c.

As shown in Fig. 5, in a door closer automatically closing a door 20 connected to a door frame 10 by using a hinge, the inventive door closer in accordance with the first embodiment comprises a first support member 11 whose one end is connected to one of the door 20 and the door frame 10, a second support member 21 connected at one end to the other of the door 20 and the door frame 10, connected at the other end to the first support member 11, and a cylinder 1 connected to one of the first support member 11 and the second support member 21. The cylinder 1 containing working fluid therewithin includes a pair of grooves 43 opposite to each other at a center portion of an internal surface and forms a space opened upwardly.

As shown in Fig. 6, the cylinder 1 includes a vertically movable body 46 having a pair of guiding protrusions 46a formed on its external surface for allowing the vertically movable body 46 to be movable along a guiding groove of the cylinder 1 and a screw 46b formed at its internal surface, a fixed shaft 41 whose one end is fixed to one of the first support member 11 and the second support member 21, while the other end having a screw 41a engaged with the screw 46b of the vertically movable body 46, a piston 45 positioned under the vertically movable body 46 and partitioning the internal space of the cylinder 1 into an upper and a lower spaces 49 and 50, an oil passage 42 formed on an inner wall of the cylinder 1 to make the upper and the lower spaces 49 and 50 to communicate with each other, a check valve 47 for allowing an oil received in the lower space 50 of the piston 45 to be flown to the upper space 49 in a unidirectional manner, a pressure control valve 48 formed with a portion of the cylinder 1 to control a pressure by the oil within the oil passage 42, and a restoring spring 60 mounted in the lower space 50 of the cylinder 1 to provide the rotated door 20 with a restoring force.

A first embodiment of the inventive vertical type door closer will now be described with reference to Figs. 5 and 6.

As shown, the cylinder 1 is fixed to the first support member 11, with the fixed shaft 41 extending from the cylinder 1 being fixed to the second support member 21. The restoring spring 60 is inserted into the lower space 50.

When the door 20 equipped with the door closer described above is opened, the piston 45 moves against the restoring spring 60 as described above.

At the moment, the vertically movable body 46 connected to the fixed shaft 41 via the screw is loosened from the fixed shaft 41 to move down to cause the piston 45 under the vertically movable body 46 to be moved down. At the same time, the oil received in the lower space 50 of the cylinder 1 is flown into the upper space 49 via the oil passage 42 and the check valve 47 due to the pressure caused by the downward movement of the piston 45.

Next, when an external force exerted on the door 20 is removed, the restoring spring 60 is restored to its initial condition to move up the piston 45, allowing the door to be closed. At the time, the fixed shaft 41 and the cylinder 1 are rotated about each other.

At the time, the vertically movable body 46 moves to its initial position, being driven into the screw of the fixed shaft 41, while the oil is flown via only the oil passage 42 due to the closing of the check valve 47, resulting that the closing movement of the door 20 is made at a reduced speed as unlike as the opening movement.

At the time, in order to avert an exceedingly quick closing or an exceedingly slow closing, the pressure control valve 48 mounted on the lower portion of the cylinder 44 can be rotated to adjust the size of the oil passage 42, which in turn adjust the flow rate of the oil to allow the closing speed of the door 20 to be controlled.

Further, as shown in Fig. 8, the vertical type door closer described above further comprises a torsion spring 30 surrounding a hinge shaft 24 positioned in the lower portion of the door 20 whose ends are fixed to the door 20 and the door frame 10, respectively, to assist a restoring force when the door 20 having a heavy weight, especially, a fireproof door, in an opened state is returned to a closed state.

The installation of the vertical type door closer and the torsion spring 30 described above with the door is described hereinbelow.

The first support members 11 and 1 la of a plate shape are mounted on an internal upside an internal downside of the door frame 10, respectively, in a parallel relationship therewith. The first support members 11 and 11 a have extensions 12 and 12a, respectively, which have hinge holes 13 and 13a formed outwardly in an opposite relationship with each other, respectively.

The second support members 21 and 21 a are mounted on an upper end and a lower end of the door 20 combined into the door frame 10, respectively. The second support members 21 and 21 a have extensions 22 and 22a, respectively, which have hinge holes 23 and 23a protruding therefrom, respectively. The hinge holes 23 and 23a communicate with the hinge holes 13 and 13a of the first support members 11 and 1 la, respectively, when the door 20 is combined into the

door frame 10.

Further, the cylinder 1 having the fixed shaft 41 protruding therefrom is mounted on a lower side of the hinge hole 23 formed through the extension 22 of the upper second support member 21. The hinge shaft 24 protruding downwardly through the hinge hole 23a of the lower second support member 21a is combined into the hinge hole 13a formed through the support member 1 la of the door frame 10.

At the moment, one end of the torsion spring 30 of a coil shape surrounding the hinge shaft 24 is coupled into a receiving groove 25 formed with the second support member 21a, while the other end is coupled into a receiving groove 14 formed with the support member 1 la of the door frame 10.

When the door is opened after the vertical type door closer is installed in this manner, the door 20 rotates under the resilience of the restoring spring 60 within the cylinder 1 and the torsion spring 30 surrounding the hinge shaft 24. The upside of the door 20 rotates about the fixed shaft 41.

Next, if the external force is removed from the door 20, the door 20 is closed by the restoring force caused by the restoring spring 60 and the torsion spring 30. At the same time, the cylinder 1 allows the door 20 to be slowly closed.

An explanation on a configuration wherein the door can be properly rotated and a constant gap between the door and the door frame can be maintained in such a manner that a sleeve shaft 31 combined with the fixed shaft 41 on the upper side of the inventive vertical type door closer using a torque is fixed to the door frame 10 to rotatably support the door and the cylinder, is now made with reference to Figs. 9a and lOb.

In the vertical type door closer of the configuration described above, the fixed shaft 41 and the cylinder 1 are coupled to the first support member 11 and the second support member 21, respectively, to rotate about each other, wherein the fixed shaft 41 is the rotating shaft.

Accordingly, if the rotation of the door is hindered, a vertical movement more easily occurs than a rotational movement, allowing the door to be vertically moved rather than to be rotated, due to a characteristic of the screw 41a which usually has multiple-thread. Accordingly, in order to prevent this problem, the upper portion of the inventive vertical type door closer has a configuration and a function like this.

A means for transmitting a torque is formed on a periphery of the fixed shaft 41.

Another means for transmitting a torque corresponding to the torque transmission means of the

fixed shaft 41 is formed inside of the sleeve shaft 3. The sleeve shaft 3 has on its lower portion a flange 4 rotatably coupled to the cylinder 1 and the second support member 21, a rotation support surface 3b formed on the lower periphery of the fixed shaft 41 to rotatably support the second support member 21, and a screw 3c formed on the upper portion of the fixed shaft 41 and combined to the first support member 11.

The torque transmission means of the fixed shaft 41 and the sleeve shaft 3 includes a hexagonal male body 41b and a female nut 3 a, and a support groove la onto which the flange 4 of the sleeve shaft 3 is rotatably received.

Since a rotation support hole 5 corresponding to the rotations support surface 3b of the sleeve shaft 3 is formed through a connection head H2 of the second support member 21, the flange 4 of the sleeve shaft 3 can be kept in place between the cylinder 1 and the second support member 21 and the cylinder 1 and the second support member 21 can rotate about the sleeve shaft 3, when the cylinder 1 is coupled to the second support member 21.

At the time, since the lower portion of the door is supported by another hinge, the sleeve shaft 3 functions to maintain a separation d between the first support member 11 and the second support member 21, and functions as a rotational shaft for ensuring the proper rotation of the two members 11 and 21. Accordingly, the problem that the door is vertically moved when the rotation of the door is hindered or a problem that the door 20 is closely fitted into the door frame 10 can be prevented.

The configuration described above can be modified like this to reduce the number of manufacturing steps. That is, as shown in Figs. 10a and lOb, a polygonal protrusion 6 may be formed on the lower side of the connection head H2 of the second support member 21, while a support groove la'may be formed to have a polygonal shape corresponding to the polygonal protrusion 6.

Hereinafter, an explanation on a configuration wherein the sleeve shaft 31 formed on the upper side of the inventive vertical type door closer includes a sleeve 33 and a flange 32, wherein the sleeve 33 functions as the rotational shaft for the second support member 21 and the cylinder 1, while a key block 9 engaged with the fixed shaft 41 for a torque transmission is fixed around the flange 32 to allow the rotation of the key block 9 to simply control an initial restoring force, is now made with reference to Figs. 11 a and 13.

The key block 9 is coupled to the upper side of the fixed shaft 41 for a torque transmission. The sleeve 33 through which the fixed shaft 41 passes, rotatably supports the

second support member 21 and the cylinder 1 by its external surface. The sleeve shaft 31 has a fixing means for fixing the key block 9 and the flange 32 fixed with the connection head H1 of the first support member 11. At the moment, the engagement between the fixed shaft 41 and the key block 9 for the torque transmission is achieved by the hexagonal male body 41b and a nut groove 7. Further, the key block 9 is engaged with a key groove 32a formed on the flange 32 of the sleeve shaft 31. Further, a tool groove 8 for a lever T for rotating the key block 9 is formed on the key block 9.

The adjustment of the restoring force in the inventive vertical type door closer described above is achieved through the process shown in Figs. 12a through 12c. In this case wherein the hexagonal male body 41b and the nut groove 7 are formed in a hexagonal shape, an adjustment by an angular size of 60 degree can be obtained.

The process is now described. As shown in Fig. 12a, the nut groove 7 of the key block 9 is combined to the hexagonal male body 41b of the fixed shaft 41 at a predetermined angle therebetween. Next, as shown in Fig. 12b, the key block 9 is aligned with the key groove 32a by rotating the key block 9 after a lever T such a large driver is inserted into the tool groove 8. As a result, the key block 9 is seated on the key groove 32a along the hexagonal male body 41b.

Finally, as shown in Fig. 12c, a nut N is combined to the screw 42c of the fixed shaft 41 to be locked therewith, as a final step for adjusting the initial restoring force.

Through the steps described above, the piston 45 positioned under the vertically movable body 46 whose screw 46b is combined to the screw 41 a of the fixed shaft 41 is moved downward to depress the spring 60 to adjust the initial restoring force.

A modification of the configuration described above is shown in Fig. 13. In the modification, a key block 9'is combined to a supporting shaft 31'via a fixing screw 10 rather than the key groove 32a.

Hereinbelow, an explanation on a configuration wherein the inventive vertical type door closer includes a restoring force adjusting oil passage 42 which is always opened and has an adjustable cross-section area, and a timing adjusting passage 70 which selectively connects a returning passage 72 with multiple passages 43b which have different meeting points with the piston 45, thereby providing an optimal initial restoring force and an optimal operational timing, is now made with reference to Figs. 14 through 16c.

The restoring force adjusting oil passage 42 whose cross-section area is adjustable is always opened. In the timing adjusting passage 70, the multiple passages 43b including a

plurality of passages having different meeting points with piston, respectively, are selectively connected to the returning passage 72 of an adjustment boss 71. The restoring force adjusting oil passage 42 and the timing adjusting passage 70 are formed on a rib 73 in a parallel relationship with each other, as shown in Fig. 15.

The adjustment of the restoring force of the inventive vertical type door closer described above is achieved as shown in Fig. 16. First, when the user opens the door 20, the working fluid received in the lower space 50 is moved to the upper space 49.

If the external force exerted on the door by the user is removed, the working fluid in the upper space 49 is moved to the lower space 50 due to the restoring force of the spring 60, as shown in Fig. 16b. At the time, since the check valve 49 is closed, the working fluid passes through only the restoring force adjusting passage 42 and the timing adjusting passage 70.

When the piston 45 is additionally moved upward to pass the multiple passages 43b of the timing adjusting passage 70, the multiple passages 43b are blocked off, allowing the working fluid to be returned via only the restoring force adjusting oil passage 42 to further reduce the closing speed of the door 20.

As described above, by fitting one of the multiple passages 43b with the returning passage 72, it is possible to adjust the operational timing of the inventive vertical type door closer.

Hereinbelow, an explanation on a configuration wherein the inventive vertical type door closer includes roller sleeves 81 and 90 and a fixed cam which are in a rolling contact and a linear contact with each other in order to momentarily fix the door 20 in a desired angular position, with the roller sleeves 81 and 90 having a fuse tube 92 for automatically closing the door when the fire breaks out, is now made with reference to Figs. 17 through 23c.

An arm 83 protrudes outwardly from one of the first support member 11 and the second support member 21. A resilient rotational shaft 82 is coupled to an upside and a downside of the arm 83. The roller sleeves 81 and 90 is installed around an external surface of the resilient rotational shaft 82 with a predetermined clearance therebetween. One or plurality of the fixed cams 84 protrudes outwardly from the other of the first support member 11 and the second support member 21 to be contacted to the external surface of the roller sleeves 81 and 90. At the time, the roller sleeves 81 and 90 selectively have a taper on an upside or a downside thereof.

The fuse tube 92 made of a metal having a lower melting point is coupled between an inner surface 93 and an outer surface of the roller sleeve 90. A plurality of drain holes 94a are formed

through the outer surface 94. At the time, the cylinder 1 is integrally coupled to the second support member 21, while the fixed shaft 41 of the cylinder being coupled to the first support member 11.

The inventive vertical type door closer having the configuration described above is not operated when the door 20 is closed as shown in Fig. 18, whereas the roller sleeve 81 is contacted to a corresponding fixed cam 84 of the second support member 21 to momentarily fix the door 20 in an opened state, when the door 20 is opened at an angle of 90 degree as indicated with a solid line in Fig. 18 or at an angle of 180 degree as indicated with a dot and dash line in Fig. 18. The plurality of fixed cam 84 may be formed, if desired.

The operation of the device described above will be described with reference to Fig. 20.

When the door is opened, the fixed cam 84 of the second support member 21 rotates clockwise with respect to the roller sleeve 81. A sluggishly slant surface of the fixed cam 84 is contacted to the roller sleeve 81, allowing the roller sleeve 81 to be contacted to the fixed cam 84 to hinder the opening of the door 20.

If the external force exerted on the door 20 is removed, the inventive vertical type door closer rotates the second support member 21 counterclockwise. At the time, since, if the rotation of the second support member 21 is continued, the roller sleeve 81 comes in the rolling contact with the fixed cam 84, the fixed cam 84 easily goes by the roller sleeve 81 to allow the door to be automatically closed.

On the other hand, if the user stops the door 20 at the momentary fixing positions, e. g., about 90 degree or 180 degree during the closing of the door 20 and then lets the door 20 alone, since the roller sleeve 81 comes in the linear contact with the fixed cam 84 in a non-rotational condition, by the frictional force, a steep slant surface is locked with the roller sleeve 81 to allow the closing door to be fixed in the opened state of a predetermined angle.

Closing the door again toward the fully closed position from the state described above is achieved by pulling the door in a closing direction or pushing the door in an opening direction and then letting the door alone. At the time, the roller sleeve 81 rotates again to come in the rolling contact with the fixed cam 84 to pass it, allowing the door 20 to be closed.

The clearance between the resilient rotational shaft 82 and the roller sleeve 81 and the slightly resilient deformation of the resilient rotational shaft 82 enables the roller sleeve 81 passing the fixed cam 84 and the fixation of the door.

The fuse tube 92 shown in Fig. 23 is melted at a predetermined temperature representing

the break-out of the fire. Especially, the fuse tube 92 in the melted state is easily drained through the drain hole 94a of the outer surface 94. If the fuse tube 92 is melted to be drained, the outer surface 94 is pushed left-ward, allowing the fixed cam 94 being locked with the outer surface 94 to be released to close the door 20.

Hereinafter, a second embodiment of the present invention is now described with reference to Figs. 24 through 29 and the drawings related to the first embodiment previously described. In the second embodiment of the present invention, a piston 45 is resiliently depressed downward and the torsion spring and the compression spring are combined with each other in order to solve the problem in that the operation of the cylinder 1 is dependent on the characteristic of the spring.

In the door closer automatically closing the door 20 connected to the door frame 10 by using a hinge, the inventive door closer in accordance with the second embodiment comprises a first support member 11 whose one end is connected to one of the door 20 and the door frame 10, a second support member 21 connected at one end to the other of the door 20 and the door frame 10, connected at the other end to the first support member 11, and a cylinder 1 connected to the second support member 21. The cylinder 1 containing working fluid therewithin includes a pair of grooves 43 opposite to each other at a center portion of an internal surface and forms a space opened upwardly. The cylinder 1 includes a vertically movable body 46 having a pair of guiding protrusions 46a formed on its external surface for allowing the vertically movable body 46 to be movable along a guiding groove of the cylinder 1 and a screw 46b formed at its internal surface, a fixed shaft 41 whose one end is fixed to the first support member 11, while the other end having a screw 41 a engaged with the screw 46b of the vertically movable body 46, a piston 45 positioned under the vertically movable body 46 and partitioning the internal space of the cylinder 1 into an upper and a lower spaces 49 and 50, an oil passage 42 formed on an inner wall of the cylinder 1 to make the upper and the lower spaces 49 and 50 to communicate with each other, a check valve 47 for allowing an oil received in the upper space 49 of the piston 45 to be flown to the lower space 50 in a unidirectional manner, a pressure control valve 48 formed with a portion of the cylinder 1 to control a pressure by the oil within the oil passage 42, and a torsion spring 61 for providing the door 20 with a restoring force by resiliently combining the fixed shaft 41 with the cylinder 1.

At the time, the piston 45 is resiliently depressed downward by the spring 61. The piston 45 is lift up to open the door 20, while being moved downward by the restoring force of

the spring 61 to close the door 20. Further, the compression spring 60 may be combined into the cylinder 1 in stead of the torsion spring 61.

Further, a compression spring 160 resiliently supporting the piston 45 may be installed in the cylinder 1. The piston 45 is resiliently depressed downward by at least one spring of the torsion spring 61 or the compression spring 160.

As shown in Figs. 24 and 25, in the second embodiment of the inventive vertical type door closer, the fixed shaft 41 is resiliently combined with the cylinder 1 through the torsion spring 61.

For this, the fixed shaft 41 has a protruding body 41d of, e. g., a rectangular shape around which a torque groove 53a of a lever 53 is combined. The lever 53 has an engagement hole 53b into which one end of the torsion spring 61a is inserted. For the convenience of the assembling workability, two of the engagement holes 53b are formed through both ends of the lever 53. Further, the lever 53 has an external shape well fitted into the internal surface of the cylinder 1 and a thickness enough to prevent the torsion spring 61 from being tilted.

The other end of the torsion spring 61 is inserted into another engagement hole lb formed through the cylinder 1.

In this configuration, since the fixed shaft 41 is resiliently combined with the cylinder 1 through the torsion spring 61, when the torsion spring 61 is deformed by the opening of the door, the restoring force 61 is directly transmitted to the fixed shaft 41.

Another application of the second embodiment of the inventive vertical type door closer is shown in Fig. 26. In the door closer, the piston 45 is moved upward against the compression spring 60 due to a rotation of the fixed shaft 41 when the door is opened, whereas the piston 45 is moved downward due to the restoring force by the compression spring 60 to rotate the fixed shaft 41, allowing the door 20 to be closed.

In this configuration, since the restoring force by the compression spring 60 is exerted downwardly, there's a tendency for the door to be depressed downward when the door is closed.

That is, even if the automatical closing of the door 20 is hindered due to the friction between the guiding protrusion 46a and the groove 43, the door 20 is depressed downward rather than upward. At this time, since the lower portion of the door 20 (not shown) is supported through a hinge, there's no hinderance, e. g., a pressured fit of the door into the door frame during the automatic closing of the door 20.

Another advantage caused by this configuration is that the hydraulic pressure of an oil

pressure is not reduced, even if the amount of the working fluid is reduced. Even if bubble occurs in the working fluid due to a repeated expansion and compression of the working fluid caused by the change of temperature of the cylinder 1, the bubble stays at only an upper portion of the cylinder 1. However, in this embodiment, since the piston 45 is moved downward during the restoring operation, the piston 45 moves in the working fluid not containing the bubble.

Accordingly, a proper damping action against the movement of the piston 45 can be made to allow the door 20 to be softly and completely closed.

The reference numerals 51 and 52 represent end caps of the cylinder 1. Two end caps are needed to allow the assembling of the fixed shaft 41, the piston 45 and the springs 60,61 and 160 to be carried out bilaterally.

Another application of the second embodiment of the inventive vertical type door closer is shown in Fig. 27, wherein the previously described applications are integrally combined with one another. In the door closer, the piston 45 is moved downward by the compression spring 160, while the fixed shaft 41 being resiliently combined with the cylinder 1 through the torsion spring 61.

In this configuration, the force for automatically closing the door 20 is provided by the torsion spring 61 directly rotating the fixed shaft 41 and the compression spring 160 applied to the piston 45 to supply the rotational force to the fixed shaft 41 via the screw 41 a.

Although this feature may seem a simple serial arrangement of the two different springs 61 and 160, requirements of the springs 61 and 160 for effecting this features are different from those in the previously described applications.

That is, since the stroke of the piston 45 in the vertical type door closer ranges within 20 mm, a great level of resilient force is needed by the spring to automatically close the heavy- weight door under such a short stroke range described above. Although the torsion spring 61 can exert a large resilient force, in a case that the two springs 61 and 160 are used, it is possible to use a normal spring not subjected to a heat treatment for increasing the strength as the torsion spring 61 since less resilient force of the torsion spring 61 is required.

Hereinafter, an explanation on a configuration wherein, in the inventive vertical type door closer in accordance with the second embodiment, forming the vertically movable body 46 and the corresponding guiding groove 43 of the cylinder 1 in a polygonal shape solves wear and damage problems, and combining the fixed shaft 41 and the vertically movable body 46 with both ends of the coil spring 60 provides a linear restoring force along with a torsional restoring

force, is now made with reference to Figs. 28 and 29.

In this application, the external shape of the vertically movable body 46 and the guiding groove 43 of the cylinder 1 into which the vertically movable body 46 is inserted have polygonal cross sections fitting with each other. Further, the cross sections of the vertically movable body 46 and the guiding groove 43 are preferably an octagonal shapes in which two continued sides are different from each other in length. However, a polygonal cross-section of any shape is available to use.

By the configuration described above, since the limitation of the rotation of the vertically movable body 46 is achieved through surface contacts of the plurality of surfaces of the polygonal shape, pressure between the vertically movable body 46 and the guiding groove 43 is reduced by far. Accordingly, the wear and the damage are reduced by far to extend the life time of the components in a great level.

Further, the compression spring 60 is mounted in such a manner that ends 60a and 60b of the compression spring 60 are inserted into the holes of a rim 41e of the fixed shaft 41 and the vertically movable body 46. As a result, the compression spring is compressed by an upward movement of the piston connected to the vertically movable body 46, being torsionally deformed by the rotation of the fixed shaft 41 at the same time. Accordingly, the coil spring 60 exerts both the linear restoring force and the rotational restoring force caused by the torsional deformation to properly make the automatic closing of the door 20. Since this coil spring 60 can exert a sufficient force by the compression and the torsion, a large spring is not required.

As described above, unlike the first embodiment, the inventive vertical type door closer in accordance with the second embodiment has a feature in that the piston 45 is adapted to be resiliently depressed downward.

Further, although the inventive vertical type door closer in accordance with the second embodiment has been described with reference to Figs. 24 through 29, it can be applied or constructed according to the configuration shown in Figs. 9a through 23c, which is applied to the first embodiment. An explanation on this application or construction is not made because it is similar to the previous description.

Although the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

The door closer in accordance with the present invention has advantage in that it enables a quick and easy opening of a door caused by a hydraulic cylinder and a slow closing of the door by using a hydraulic pressure in order to prevent slam of the door and to ensure a convenient use for the user.