Door hinge

Abstract: According to the invention, there is provided a door hinge comprising a spring (10) that plays the role of both a torsion spring and a compression spring, wherein its resilient force is used for axially pressing a movable cam (9) against a matching fixed cam (6) it comprises and thereby facilitating the opening and closing motion of the door with which it is used by giving said cams such specific configurations that the spring (10) accelerates the opening motion of the door from a given angular position of the door and locks the door at a particular open position and at a closed position. Since a door using such a hinge that comprises a spring (10) whose resilient force constantly biases the door to open can be either opened to any de­ sired angle or closed and sustained there under a locked condition when the rotary shaft (8) of the hinge is firmly connected to the door, it can be used for a flap door or another vertically rotatable door such as a toilet lid to sustain the door to an open position under a locked condi­ tion even if the resilient force of the spring is nulli­ fied at that position and the door is liable to be pushed back by an obstacle such as a wire located behind the toilet assembly comprising the lid. Therefore, the door is protected against any turning effort and other forces which are unintentionally applied to the door.

Description: This invention relates to a hinge which can be used for a door such as an ordinary swing door, or for a flap door including a vertically pivoting flap door typically used for a toilet lid or the like. Door hinges are known that utilize a viscous fluid, such as polyisobutylene or a similar high molecular viscous fluid, in combination with a spring in order to obtain a high resistance to abrupt motion of the door in one direction: use is made of the viscous shearing resistance of the viscous fluid and the torsional resistance of the spring to provide smooth and easy rotary movement. However, with a door hinge of this type where the resilient force of the spring is used to bias the door only in the direction of opening, it can become very heavy when it is being closed. In order that the door can be closed without difficulty, the hinge may require some additional mechanism, which in turn makes the overall hinge structure very complicated. FR-A-1422988 discloses a hinge comprising a shaft for connecting to a door or the like, a casing to which the shaft is rotatably mounted, a movable cam slidably mounted on the shaft and being arranged to rotate therewith and a spring arranged to bias the movable cam axially along the shaft into face-to-face contact with a cam fixed to the casing, the contacting faces of the cams being profiled so that the cams lock the shaft relative to the casing at a predetermined angular position within a range of rotational angles of the shaft. In particular, the hinge is used for a door and the cams lock the door at predetermined position to prevent swinging movement. US-A-2814049 discloses a hinge for a toilet seat, in which a spring applies a torsional force to bias the seat in the opening direction. In accordance with this invention, there is provided a hinge comprising a shaft for connecting to a door or the like, a casing to which the shaft is rotatably mounted, a movable cam slidably mounted on the shaft and being arranged to rotate therewith, and a spring arranged to bias the movable cam axially along the shaft into face-to-face contact with a cam fixed to said casing, the contacting faces of the cams being profiled so that the cams lock the shaft relative to the casing at a predetermined angular position within a range of rotational angles of the shaft, the hinge being characterised in that the spring is also arranged to apply a torsional force to the shaft to bias the shaft in a predetermined rotary direction relative to the casing. In use of this hinge, any external force applied to the door, to which the hinge is fitted, serves as a rotary force for rotating the rotary shaft of the hinge either in the direction of opening or in the direction of closure of the door. As the rotary shaft is rotated along with the movable cam which it carries, the spring fitted thereto is twisted to generate a torque for returning the door in the opposite direction. Assuming, for instance, that a flap door is provided with the hinge and rotates between a 0° angular position, or closed position, and a 110° angular position, or fully open position and that, when the flap door rotates with the rotary shaft of the hinge for closure, it twists the spring in the hinge to store torsional energy, then the spring naturally accelerates the opening motion of the door to make it easier for the user to open the door. The spring is also utilized to press the movable cam against the fixed cam: preferably the movable cam is provided with a number of ribs each having an inclined side wall, while the fixed cam is provided with the same number of grooves each having a matching inclined side wall. The movable cam is rotated until its ribs are located on the respective inclined side walls of the grooves of the fixed cam and then eventually comes to rest to lock the door at its maximum open position (110° angular position). Therefore, if the door is opened to an intermediary angular position (e.g. 100° angular position) which is close to the maximum angular position (110° angular position), where the ribs of the movable cam are already located on the respective inclined side walls of the grooves of the fixed cam, the movable cam is inevitably rotated further until it is completely engaged with the fixed cam because of the sliding motion of its ribs on the inclined side walls of the grooves of the fixed cam, and the door is locked to that angular position to prevent any accidental or unintentional closing motion of the door. In other words, preferably the fixed and movable cams of the hinge are so configured that a torque is generated to further open the door once the door is opened to a given angular position. The performance of the hinge may be altered by modifying the configuration of the fixed and movable cams so that the door to which the hinge is fitted may be locked to a different angular position or to a fully closed position. Also, in accordance with this invention, there is provided a hinge comprising a shaft for connecting to a door or the like, a casing to which the shaft is rotatably mounted, a movable cam slidably mounted on the shaft and being arranged to rotate therewith and a spring disposed between the movable cam and a spring carrier fixed to the shaft to bias the movable cam axially along the shaft into face-to-face contact with a cam fixed to said casing, the hinge being characterised in that the spring has its opposite ends engaged respectively with the spring carrier and an axially extending groove formed in the casing, the spring being arranged to apply a torsional force to the shaft to bias the shaft in a predetermined rotary direction relative to the casing, the contacting faces of the cams are profiled so that a rotational torque is applied to the shaft by the axial compressive force of the spring when the shaft is within a range of rotational angles relative to the casing a member is rotatably mounted within the casing, a space between the movable member and the casing being filled with a viscous fluid, and a spring clutch is connected between the movable member and the spring carrier such that the movable member rotates with the shaft in one direction of shaft rotation only. In use of this hinge, any external force applied to the door, to which the hinge is fitted, serves as a rotary force for rotating the rotary shaft of the hinge either in the direction of opening or in the direction of closure of the door. The spring carrier, with which the rotary shaft is engaged, is engaged with or disengaged from the movable member by means of the spring clutch depending on the direction of rotation: thus the movable member does not rotate with the rotary shaft when the shaft rotates in a given direction and therefore no viscous shearing resistance is generated within the viscous fluid of the hinge. Assuming, for instance, that a flap door is provided with the hinge and rotates between a 0° angular position, or closed position, and a 110° angular position, or fully open position and that, when the flap door rotates with the rotary shaft and the spring carrier for closure, it twists the spring in the hinge to store torsional energy, then the spring naturally accelerates the opening motion of the door to make it easier for the user to open the door. Preferably the spring carrier and the movable member are engaged by means of the spring clutch during the closing motion, so that the movable member is rotated with the rotary shaft and the spring carrier to generate viscous shearing resistance in the viscous fluid contained in the space between the movable member and the casing of the hinge, so that the hinge operates as a damper that resists the rotation of the rotary shaft. Consequently, thanks to the resilient force of the spring and the viscous shearing resistance of the viscous fluid, the door will be closed smoothly and softly. The spring is also utilized to press the movable cam against the fixed cam, so that a torque is generated within the hinge to accelerate rotation of the shaft, preferably in the opening direction of the door, at least when the door has been opened to a predetermined angular position (e.g. 55° angular position) and until the door reaches its maximum angular position (110° angular position), where preferably it is locked. The performance of the hinge may be altered by modifying the configuration of the fixed and movable cams so that the door to which the hinge is fitted may be locked to a different angular position or to a fully closed position. In another embodiment, the fixed cam and the movable cam of the hinge are so configured that, as the door to which the hinge is fitted comes close to its fully closed position, the door is subjected to a torque generated by the spring, trying to move the door in the other direction. Consequently the door is closed softly and smoothly. When the door is fully closed and then opened slightly, the spring presses the movable cam against the fixed cam so that the rotary shaft is subjected to a torque that accelerates the opening motion of the door in the initial stages of the opening operation to make it easier for the user to open it. Now the present invention will be described in greater detail by referring to the accompanying drawings that illustrate preferred embodiments of the invention. In the drawings: Of Figs. 1 through 7 showing a first embodiment of the hinge of the invention, Fig. 1 is a longitudinal sectional view of the embodiment when it is locked; Fig. 2 is a longitudinal sectional view of the embodiment when it is released from the locked condition; Fig. 3 is an exploded perspective view of the embodiment; Figs. 4(a) and (b) are perspective views respectively showing the movable cam and the fixed cam of the embodiment; Figs. 5(a) and (b) are longitudinal sectional views showing the positional relationship among the fixed cam, the movable cam, the spring and the rotary shaft respectively when the embodiment is locked and when it is unlocked; Figs 6(a), (b) and (c) are radial sectional views showing the engagement between the fixed cam and the movable cam under three different positional conditions; and Fig. 7 is a side view of a toilet assembly incorporating the embodiment of the invention. Of Figs. 8 through 12 showing a second embodiment of the door hinge of the invention, Fig. 8 is a longitudinal sectional view of the embodiment when it is locked; Fig. 9 is a longitudinal sectional view of the embodiment when it is released from the locked condition; Figs. 10(a) and (b) are perspective views respectively showing the movable cam and the fixed cam of the embodiment; Figs. 11(a) and (b) are radial sectional views showing the engagement between the movable cam and the fixed cam under two different positional conditions; and Fig. 12 is a side view of a toilet assembly incorporating the embodiment of the invention. Of Figs. 13 through 17 showing a third embodiment of the door hinge of the invention, Fig. 13 is a partially sectional side view of the embodiment when it is locked; Fig. 14 is a partially sectional side view of the embodiment when it is released from the locked condition; Figs. 15(a) and (b) are perspective views respectively showing the movable cam and the fixed cam of the embodiment; Figs. 16(a), (b) and (c) are radial sectional views showing the engagement between the movable cam and the fixed cam under three different positional conditions; and Fig. 17 is a schematic plan view of a door incorporating the third embodiment. Figs. 18(a) and (b) are respectively perspective views of the movable cam and the fixed cam of a fourth embodiment of the invention. Figs. 19(a) and (b) are sectional views showing the engagement of the fixed cam and the movable cam of the fourth embodiment under two different positional conditions. Fig. 20 is a side view of a toilet assembly incorporating the fourth embodiment. Figs. 21(a) and (b) are respectively perspective views of the movable cam and the fixed cam of a fifth embodiment of the invention. Figs. 22(a), (b) and (c) are sectional views showing the engagement of the fixed and the movable cam of the fifth embodiment under three different positional conditions. Fig. 23 is a side view of a toilet assembly incorporating the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION Figs. 1 through 7 illustrate a first embodiment of the invention. As seen from Figs. 1 through 3, horizontally placed cylindrical casing 1 comprises a projection 1b inwardly extended from the center of the inner surface of its end wall 1a and a threaded section 1c arranged at the inner periphery of its other end as well as a plurality of longitudinal grooves 1d... crossing said threaded section 1c. Horizontally placed cylindrical and movable shell 2 has a length which is approximately a half of the effective length of the inside of said casing 1 and an outer diameter which is slightly smaller than the inner diameter of the casing. Its end wall 2a is provided at the center of its outer surface with a bore 2b for receiving said projection 1b and on the outer periphery near its open end with a circular groove 2d for receiving a O-ring 3 so that the casing 1 and the movable shell 2 are axially rotatable relative to each other and the space A between them is airtightly sealed by the ring 3. The space A is thus defined by the end wall 1a and the peripheral wall 1e of the casing 1 and the end wall 2a and the peripheral wall 2e of the movable shell 2 and contains in it viscous fluid B that can be a high molecular viscous fluid such as polyisobutylene, pitch or highly viscous water glass. Horizontally placed cylindrical spring carrier 4 comprises along its axis a cylindrical recess 4a and a polygonal hole 4b arranged side by side as well as a flange 4c on its outer periphery outwardly and radially projecting from the end closer to the recess 4a. Said spring carrier 4 is so arranged within said movable shell 2 that it is rotatable around the axis of the casing 1 by means of a spring one-way clutch 5 disposed between the recess 4a and the projection 2c of the movable shell 2. Said spring one-way clutch 5 is realized by winding a highly resilient steel wire having a rectangular or circular cross section to form a densely wound coil which presses itself against the inner peripheral surface of the recess 4a of said spring carrier 4, an end 5a of said clutch 5 projecting perpendicularly relative to its axis and received by a recess 2f formed on the projection 2c of the movable shell 2, the other end 5b being left free within the space provided for the clutch 5. The fixed cam 6 has a disc-like form with a considerable thickness and is provided with an axial through bore 6a and a plurality of axially extending ribs 6b... arranged on its outer periphery and received by the respective grooves 1d... of the casing for engagement, said fixed cam being securely held by a lid plate 7 which is screwed into the threaded section 1c of the casing 1 so that it is not axially movable nor rotatable around its axis. As shown in Figs. 4(b), 6(a), 6(b) and 6(c), said fixed cam 6 is provided with three radially extending grooves 6c... arranged on its inner end surface 6d and equally spaced apart from one another, each of said grooves 6c... having an inclined side wall 6e between the inner end surface 6d of the cam 6 and the bottom of the groove. The rotary shaft 8 runs through the through bore 6a of the fixed cam 6 so that it is rotatable around the axis of the casing 1. Said rotary shaft 8 has a polygonal extension 8a, the end of which is received by the matching polygonal hole 4b of the spring carrier 4 for being tightly engaged therewith. As shown in Figs. 3, 4(a), 6(a), 6(b) and 6(c), the movable cam 9 also has a disc-like form with a considerable thickness and is provided with an axial and polygonal through bore 9a and three radially extending ribs 9c... arranged on an end surface 9b and equally spaced apart from one another, said ribs being engaged with the corresponding respective grooves 6c... of the fixed cam 6. More specifically, each of the ribs 9c of the movable cam 9 has an inclined side wall 9d that matches the inclined side wall 6e of the fixed cam 6. The movable cam 9 is so arranged around said polygonal extension 8a of the rotary shaft 8 within the casing 1 and between the spring carrier 4 and the fixed cam 6 that it is not freely rotatable around the axis of the casing but axially slidable relative to the rotary shaft 8. In other words, as the movable cam 9 rotates with the rotary shaft 8, its ribs 9c... come into engagement with the corresponding respective grooves 6c... and then disengaged therefrom. The spring 10 is located within said casing 1 with its ends respectively abutting the flange 4c of the spring carrier 4 and a surface of said movable cam 9. As illustrated, the spring 10 is a coil spring which is so designed that it biases the rotary shaft 8 in one direction, resists any rotary movement of the shaft 8 in the other direction and at the same time press the movable cam 9 against the fixed cam 6. Therefore, when the spring 10 is not compressed, it has a length significantly greater than the distance between the flange 4c of the spring carrier 4 and the spring receiving surface of the movable cam 9. As mentioned earlier, an end 10a of said spring 10 is received by the flange 4c of the spring carrier 4, while its other end 10b is slidably received by an axially extending groove 1f formed on the inner periphery 1e of the casing 1. The spring 10 may be forcibly twisted before its ends 10a and 10b are received by the respective receiving members so that the rotary shaft 8 is angularly biased by the spring by a certain angle from the angle of reference, or angle 0°. The portion of the rotary shaft 8 which is projecting from the casing 1 is rigidly connected to the center of rotation of a door or a similar item (not shown) so that an external turning effort is applied thereto. As the rotary shaft 8 and the spring carrier 4 are rotated in one direction or the direction indicated by arrow C in Fig. 1, the spring one-way clutch 5 comes to closely contact with the inner peripheral surface of the recess 4a of the spring carrier 4 until the movable shell 2 is connected and rotates with the rotary shaft 8 and the spring carrier 4. When, on the contrary, the rotary shaft 8 and the spring carrier 4 are rotated in the other direction or the direction indicated by arrow D in Fig. 1, the spring one-way clutch 5 comes to slide on the inner peripheral surface of the recess 4a so that it is eventually disconnected from the rotary shaft 8 and the spring carrier 4. In short, the spring one-way clutch 5 plays the role of sustaining or disrupting the power transmission path constituted by the rotary shaft 8, the spring carrier 4 and the movable shell 2 depending on the direction of rotation of the rotary shaft 8 and the spring carrier 4. When a hinge having a configuration as described above is used for a toilet seat and a toilet lid as illustrated in Fig. 1 or a flap door (not shown), the rotary shaft 8 is connected to the toilet seat 11 and the casing is fitted to a toilet seat holding member, or a toilet bowl 12, in such a manner that the toilet seat 11 can be pivoted by an angle greater than 90° between its horizontal closed position, or angle 0° position, and its wide open position, or angle 110° position, as illustrated in Fig. 7. It should be noted that the opening movement of the toilet lid corresponds to the rotation of the rotary shaft 8 in the direction indicated by arrow D in Fig. 1. When the toilet seat 11 is opened from its angle 0°position and the rotary shaft 8 is rotated in the direction of arrow D, the spring carrier 4 is also rotated in the direction of arrow D due to the fact that it is engaged with the rotary shaft 8, that the spring carrier 4 is biased in the direction of arrow D by the spring 10 and that the rotary shaft 8 is subjected to the resilient force of the spring 10 in the direction of arrow D by way of the spring carrier 4. The rotation of the spring carrier 4 results in reduction of the diameter of the spring one-way clutch 5, which in turn releases the tight connection of the spring one-way clutch 5 and the spring carrier 4 so that the connection between the spring carrier 4 and the movable shell 2 is also released to produce a clutch "disconnected" condition, where only the rotary shaft 8 and the spring carrier 4 are rotated in the direction of arrow D while the movable shell 2 is not rotated and therefore the shearing resistance of the viscous fluid B remains inoperative. While the movable cam 9 is rotated with the rotary shaft 8 in the direction of arrow D because of their mutual engagement, the front ends of the ribs 9c... are pressed against the surface 6d of the fixed cam 6 under a condition as illustrated in Fig. 6(a). As the rotary shaft 8 is further rotated in the direction of arrow D by the opening motion of the toilet seat 11 until the latter reaches the angle 100° position as illustrated in Fig. 7, the ribs 9c... of the movable cam 9 move to the corresponding inclined side walls 6e... of the fixed cam 6. Under this condition, a torque is generated within the system to accelerate the opening motion of the toilet seat 11 because of the resilient force of the spring 10 trying to bias the movable cam 9 toward the fixed cam so that said ribs 9c are guided into the respective grooves 6c... along the inclined side walls 6e... until said ribs 9c... are completely received by the respective grooves 6c... and therefore the movable cam 9 is securely engaged with the fixed cam to lock the toilet seat 11 (rotary shaft) to its open position (angle 110° position). When, to the contrary, the toilet seat 11 is closed and the rotary shaft 8 is rotated in the direction of arrow C of Fig. 1 along with the spring carrier 4, the spring one-way clutch 5 comes to tightly contact with the inner peripheral surface of the recess 4a of the spring carrier 4 to connect the movable shell 2 with the spring carrier 4 and the rotary shaft 8 so that the movable shell 2 is rotated with the rotary shaft 8 to generate a viscous shearing resistance in the viscous fluid B that resists the rotary movement of the rotary shaft 8. Since, at this stage, the coil spring 10 is twisted further by the rotation of the spring carrier 4, it exerts a resistance against the rotary movement of the rotary shaft 8 to slow down the closing action of the toilet seat 11 until it smoothly and softly reaches the closed position, or angle 0° position. Moreover, since the movable cam 9 is rotated in the direction of arrow C of Fig. 1 with the rotary shaft 8 from the position as indicated in Fig. 6(C), the ribs 9c... of the movable cam 9 climb up the respective inclined side walls 6e... of the grooves 6c... against the resilient force of the spring 10 until they get to the surface 6d of the fixed cam 6 to release the toilet seat 11 from the open and locked condition. Arrow E in Fig. 7 indicates the direction in which the resilient force of the spring 10 is applied to the rotary shaft 8 and therefore the toilet seat 11 and arrow F indicates the direction of viscous shearing resistance of the viscous fluid B, whereas arrow G shows the direction where no viscous shearing resistance is traced. Figs. 8 through 12 illustrate a second embodiment of the invention. As seen from Figs. 8 through 12, casing 1 comprises a cylindrical projection 1g standing from the center of its end 1a, an axial bore 1h being formed along the axis of said cylindrical projection 1g. Rotary shaft 8 runs through the axial through bore 6a of a fixed cam 6 which is rigidly held by the casing 1 so that the rotary shaft 8 and the casing 1 are concentric relative to each other. An extension of said rotary shaft 8 which is found within the casing 1 is rotatably received by the axial bore 1h and the portion of said extension between the outer end of the cylindrical projection 1g and the movable cam 6 forms a polygonal section 8a, a movable cam 9 being arranged around said polygonal section 8a in such a manner that it is axially slidable relative to the rotary shaft 8 and rotatable around axis of rotation of the rotary shaft 8 with the latter. A spring 10 is arranged within the casing 1 between the inner surface of the end 1a and the inner surface of the movable cam 9, its one end 10a being bent to form a hook and held within a recess 1i formed on said end 1a, its other end 10b being received by an axial groove 8b formed on said movable cam 9 so that it is slidable only in the axial direction and therefore said spring 10 may be twisted further when the rotary shaft 8 is rotated in the direction of arrow C in Fig. 8. The effective length of said spring 10 is so selected that it is longer than the distance between the inner surface of the end 1a of the casing 1 and the inner surface of the movable cam 9 and therefore the movable cam 9 is constantly biased toward the fixed cam 6 by the spring 10. The fixed cam 6 has on its surface facing the movable cam 9 three radial grooves 6e... which are spaced apart from one another by the same angle, or 120°, and has a substantially semicircular cross section, while the movable cam 9 is provided with three corresponding radial ribs 9c... which are also equally spaced apart from one another and has a substantially semicircular cross section so that they may be engaged with and disengaged from the respective grooves 6e.... It should be noted that, unlike the first embodiment, this second embodiment is not provided with a movable shell 2, nor with a spring carrier 4 and therefore not with a viscous fluid B. When said second embodiment is used for a toilet seat 11 of a toilet assembly as illustrated in Fig. 12, the rotary shaft 8 is connected to the toilet seat 11 in a manner similar to that of the first embodiment. When the toilet seat 11 is opened from its closed position, or angle 0° position, and the rotary shaft 8 is rotated in the direction of arrow D in Fig. 8, the movable cam 9 is rotated with said rotary shaft 8 in that direction and the rotary shaft 8 is biased in the same direction by the spring 10 while the ribs 9c... of the movable cam 9 are pressed against the inner surface 6d of the fixed cam 6 by the spring 10 as illustrated in Fig. 11(a). As the toilet seat 11 is opened further until it reaches the full open position, or angle 110° position, the ribs 9c... of the movable cam 9 are fully received by the respective grooves 6c... of the fixed cam 6 for mutual engagement of the movable and fixed cams 6 and 9 and the toilet seat 11 is locked to its position (angle 110° position). When the toilet seat 11 is closed from the open position, the rotary shaft 8 is rotated in the direction as indicated by arrow C in Fig. 8 and the spring 10 is twisted also in that direction so that the resilient force of the spring 10 resists the rotation of the rotary shaft 8 and consequently the toilet seat 11 is smoothly and softly closed to its fully closed position, or angle 0° position. At this stage, the ribs 9c... of the movable cam 9 are released from the engagement with the respective grooves 6c of the fixed cam 6 by the rotary movement of the movable cam 9 in the direction of arrow C against the biasing force of the spring 10 so that the toilet seat 11 is unlocked from its open position. Figs. 13 through 17 illustrate a third embodiment of the invention. This embodiment differs from the first embodiment in that the fixed cam 6 and the movable cam 9 have profiles which are different from those of the fixed and movable cams 6 and 9 of the first embodiment. In this embodiment, the inclined side wall 6e of each of the recesses 6c... of the fixed cam 6 and the matching inclined side wall 9d of each of the ribs 9c... of the movable cam 9 are arranged on the side opposite to that of their counterparts of the first embodiment. Otherwise, this third embodiment is configured similarly as the first embodiment. When this embodiment is used for an ordinary swing door 11a as illustrated in Fig. 17, the rotary shaft 8 is connected to the door 11a in a manner similar to that of the first embodiment. When the door 11a is turned open from its angle 0° position in a direction as indicated by arrow D, the rotary shaft 8 is rotated with the movable cam 9 also in the direction of arrow D until the door 11a reaches the full open position, or angle 110° position because of the resilient force of the spring 10 applied to the rotary shaft 8. When, to the contrary, the door 11a is turned for closure, the rotary shaft 8 is rotated in the direction of arrow C to twist further the spring 10 as in the case of the first embodiment so that the door 11a is closed smoothly and softly by the resilient force of the spring and the viscous shearing resistance of the viscous fluid in the hinge assembly that resist any abrupt closing movement of the door 11a. As the movable cam 9 is rotated with the rotary shaft 8 in the direction of arrow C and the door 11a comes close to its fully closed angle 0° position or point H in Fig. 17, it is pressed against the inner surface 6d of the fixed cam 6 by the spring 10 and the front edges of the ribs 9c... of the movable cam 9 move to the respective inclined side walls 6e... of the grooves 6c... of the fixed cam 6 as illustrated in Fig. 16(a). Then, the inclined side walls 9d... of the movable cam 9 slide on the respective inclined sides walls 6e... of the fixed cam 6 until the ribs 9c... of the movable cam 9 comes to be fully engaged with the respective recesses 6c... of the fixed cam 6 as shown in Fig. 16(b) so that the door 11a moves from the point H to the angle 0° position and locks there. It should be noted that the arrows E, F and G in Figs. 12 and 17 respectively indicate directions which are same as those indicated by the arrows E, F and G in Fig. 7. According to a fourth embodiment of the invention, there is provided a hinge having a configuration which is essentially identical with that of the above first embodiment but differs from it in the sense as described below. Like the above first embodiment, a hinge according to the fourth embodiment of the invention comprises a relatively thick disc-shaped fixed cam 6 having a central circular axial through bore 6a and a plurality of axial ribs 6b... arranged on its outer peripheral surface, said axial ribs 6b... being received by corresponding respective axial grooves 1d... of a casing 1 and rigidly held there by means of a lid plate 7 which is screwed into the threaded section 1c of the casing 1 so that it may not axially move nor rotate. However, as seen from Figs. 18 and 19, the inner surface 6d is realized in the form of an inclined surface 6e and a perpendicular wall 6h whose height is defined by the highest portion 6f and the lowest portion 6g of the inclined surface 6e. As shown in Figs. 18(a), 19(a) and 19(b), the hinge also comprises a relatively thick disc-shaped movable cam 9 having a central polygonal axial through bore 9a and its outer surface 9d is realized in the form of an inclined surface and a perpendicular wall 9g that respectively corresponds to the inclined surface 6e and the perpendicular wall 6h of the fixed cam 6, the height of which is defined by the highest portion 9e and the lowest portion 9f of the inclined surface 9d. Said movable cam 9 is fitted to polygonal extension 8a of a rotary shaft 8 in such a manner that it is axially movable but not peripherally so that it freely rotates with the rotary shaft 8 and may be engaged with or disengaged from the fixed cam 6 as it axially moves as illustrated in Fig. 19(a) and (b) A hinge according to the fourth embodiment of the invention operates in the following manner. Referring to Fig. 20, as the toilet seat 11 to which the hinge is applied is rotated from its closed position S1 to a first open position S2 (e.g. opened by 55°), the highest portion 9e of the movable cam 9 is moved to the inclined surface 6e of the fixed cam 6 as shown in Fig. 19(a) and a torque is generated to open the toilet seat 11 because of the effect of the spring 10 as a compression spring and the shape of the two cams 6 and 9 so that the movable cam 9 is rotated in the direction of arrow D of Fig. 19(b) through the mutual action of the two inclined surfaces 6d and 9c until the perpendicular walls 6h and 9g of the cams 6 and 9 abut each other. Consequently, the toilet seat 11 is opened up to a full open position S3 and locked there. When, to the contrary, the toilet seat 11 is moved for closure from its full open position, the rotary shaft 8 and the spring carrier 4 are rotated in the direction of arrow C in Fig. 1 and the spring one-way clutch 5 comes to closely contact with the inner peripheral wall of the recess 4a of the spring carrier 4 and connect the movable shell 2 with the spring carrier 4 and the rotary shaft 8 so that the movable shell 2 is rotated with the rotary shaft 8 and a viscous shearing resistance is generated in the viscous fluid B to hinder the rotation of the rotary shaft 8. At this stage, the spring 10 is twisted further by the rotation of the spring carrier 4 and therefore the rotation of the rotary shaft 8 is hindered by the resilient force of the spring 10. As a result, the toilet seat 11 is moved smoothly and softly until it reaches a closed position S₁. Since the movable cam 9 is rotated with the rotary shaft 8 in the direction of arrow C shown in Fig. 1, the movable cam 9 and the fixed cam 6 are relatively separated from each other as the movable cam 9 is rotated because the inclined surface 9d climbs up the inclined surface 6e of the fixed cam 6. According to a fifth embodiment of the invention, there is provided a hinge having a configuration which is essentially identical with that of the first embodiment described earlier but differs from it in the sense as stated below. As illustrated in Figs. 21(b) and 22(a), a hinge according to the fifth embodiment of the invention comprises a relatively thick disc-shaped fixed cam 6 having three radial grooves 6c... on its inner surface 6d which are equally spaced apart from one another, one of the side walls of each of said grooves 6c... being formed as an inclined side wall 6e stretching from the inner surface 6d down to the bottom of the groove 6c, the other side wall being a perpendicular side wall 6i. As seen from Fig. 21(a), the movable cam 9 of the hinge is realized in the form of a relatively thick disc having a polygonal central axial through bore 9a and three radially extending ribs 9c... on its outer surface which are equally spaced apart from one another. Each of the ribs 9c... has a profile that corresponds to that of the groove 6c that receives it although the width of the former is a little smaller than that of the groove 6c so that the movable cam 9 may be slightly rotated even when the ribs 9c... are fully engaged with the respective grooves 6c.... Each of said ribs 9c... has an inclined side wall 9d that matches the corresponding inclined side wall 6e of the fixed cam 6 and a perpendicular side wall 9h that also matches the corresponding perpendicular side wall 6i of the fixed cam 6. Said movable cam 9 is fitted to an polygonal extension 8a of the rotary shaft 8 between the spring carrier 4 and the fixed cam 6 in such a manner that it is axially slidable but peripherally not slidable relative to the rotary shaft 8 and that it is rotatable with the rotary shaft 8 so that it may be engaged with and disengaged from the fixed cam 6 as illustrated in Figs. 22(a) and (b). A hinge according to the fifth embodiment of the invention operates in the following manner. Referring to Fig. 23, when the toilet seat 11 is slightly moved from its closed position, or position S1, to an open position, or position S4, the ribs 9c... of the movable cam 9 come to abut the respective inclined side walls 6e... of the fixed cam 6 as illustrated in Fig. 22(b). Under this condition, the inclined side walls 9d... of the movable cam 9 slide down the respective inclined side walls 6e... of the fixed cam 6 by the axially biasing effect of the spring 10 and consequently the movable cam 9 is rotated in the direction of arrow D. In other words, a torque is generated within the hinge to turn the rotary shaft 8 and the toilet seat 11, which is therefore moved with ease by a light initial opening effort of the user. As the toilet seat 11 passes the position S4 illustrated in Fig. 23, the ribs 9c of, the movable cam 9 come to be engaged with the respective grooves 6c... of the fixed cam 6. Consequently, the torque of the hinge, due to the axial bias of the spring, is reduced to nil, as it is in the closed position S1. Now, the toilet seat 11 is moved to its open position S3 by the resilient force of the spring 10. When, to the contrary, the toilet seat 11 is moved from its open position, the rotary shaft 8 and the spring carrier 4 are rotated in the direction of arrow C of Fig. 1 to bring the spring one-way clutch 5 into a tight contact with the spring carrier 4 so that the movable shell 2 is connected with the spring carrier 4 and the rotary shaft 8 and the movable shell 2 is rotated to generate a viscous shearing resistance within the viscous fluid B that resists the turning effort of the rotary shaft 8. Since the spring 10 is twisted further by the rotation of the spring carrier 4 at this stage, the resilient force of the spring 10 deters any abrupt motion of the toilet seat 11 so that it is moved smoothly and softly to its closed position S1. Under this condition, as the movable cam 9 is rotated from the position as shown in Fig. 22(c) in the direction of arrow C in Fig 1 or in the direction opposite to arrow D in Fig. 22(c), the movable cam 9 is rotated while its inclined side walls 9d... climb the respective inclined side walls 6e of the fixed cam 6 to the left in Fig. 1 to compress and at the same time shift the spring 10 leftward as seen in Fig. 2. Consequently, the ribs 9c... of the movable cam 9 are pressed hard against the inner surface 6d of the fixed cam 6 by the spring 10. The pressure of the spring 10 acts as a braking force for the closing movement of the toilet seat 11 at the final stages of its closure. Thus, the toilet seat 11 is smoothly and softly moved from the open position S4 in Fig. 23 to the closed position S1. As is apparent from the above detailed description of the present invention, since a door using a hinge according to claim 1 and comprising a spring whose resilient force constantly biases the door to open can be either opened to any desired angle or closed and sustained there under a locked condition when the rotary shaft of the hinge is firmly connected to the door, it can be used for a flap door or another vertically rotatable door such as a toilet lid to sustain the door to an open position under a locked condition even if the resilient force of the spring is nullified at that position and the door is liable to be pushed back by an obstacle such as a wire located behind the toilet assembly comprising the lid. Therefore, the door is protected against any turning effort and other forces which are unintentionally applied to the door and can be kept to an open position, although it can be turned back to the closed position smoothly and softly against the resilient force of the spring it comprises and locked to that position so that any abrupt motion of the door may be eliminated. Moreover, since the hinge may be so designed that it can generate a torque for both opening and closing the door by altering the profile of the fixed and movable cams, there may be provided, if necessary, a door that can be opened or closed from a certain intermediary position to a fully open or closed position and locked there. Since a single spring can meet all these requirements, the hinge is configured with a very simple structure and therefore can be prepared at a low cost. A flap door or a toilet lid provided with a hinge according to claim 2 and having a rotary shaft rigidly connected to the door can be opened to any angular position by the spring it comprises that operates as a torsion spring to that position and thereafter acts as a compression spring for pressing a movable cam against a fixed cam to generate a torque for further opening the door so that the door may be turned smoothly and softly to its fully open position and locked there. Then, the door may be smoothly and softly turned back to its closed position thanks to the torque generated within the hinge for opening the door, the resilient force of the spring and the viscous shearing resistance of the viscous fluid it contains that tend to offset the abrupt closing motion of the door. Since the door may be so designed as to be opened to any desired angular position by altering the profile of the fixed and movable cams, the door may perform any selected action in terms of opening and closing. Moreover, since a single spring is used as both a torsion spring and a compression spring, the hinge is configured with a very simple structure and therefore can be prepared at a low cost. Since a flap door or a toilet lid using a hinge according to claim 3 and comprising a spring that operates as a compression spring for constantly biasing a movable cam to a fixed cam it comprises which, if appropriately configured, generate a torque for rotating the rotary shaft in the direction of opening the door, the initial stages of the opening operation of the door are carried out particularly smoothly and softly. Moreover, the closing action of the door is also soft and smooth because the torque for rotating the rotary shaft in the direction of opening the door decelerates the closing motion of the door. Here again, since a single spring is used as both a torsion spring and a compression spring, the hinge is configured with a very simple structure and therefore can be prepared at a low cost.

Claims: A hinge comprising a shaft (8) for connecting to a door or the like, a casing (1) to which the shaft (8) is rotatably mounted, a movable cam (9) slidably mounted on the shaft and being arranged to rotate therewith, and a spring (10) arranged to bias the movable cam (9) axially along the shaft (8) into face-to-face contact with a cam (6) fixed to said casing (1), the contacting faces of the cams (6,9) being profiled so that the cams (6,9) lock the shaft (8) relative to the casing (1) at a predetermined angular position within a range of rotational angles of the shaft, the hinge being characterised in that the spring (10) is also arranged to apply a torsional force to the shaft (8) to bias the shaft (8) in a predetermined rotary direction relative to the casing (1). A hinge comprising a shaft (8) for connecting to a door or the like, a casing (1) to which the shaft (8) is rotatably mounted, a movable cam (9) slidably mounted on the shaft and being arranged to rotate therewith, and a spring (10)disposed between the moveable cam (9) and a spring carrier (4) fixed to the shaft (8) to bias the movable cam (9) axially along the shaft (8) into face-to-face contact with a cam (6) fixed to said casing (1), the hinge being characterised in that the spring (10) has its opposite ends engaged respectively with the spring carrier (4) and an axially extending groove (1F) formed in the casing (1), the spring (10) being arranged to apply a torsional force to the shaft (8) to bias the shaft (8) in a predetermined rotary direction relative to the casing (1), the contacting faces of the cams (6,9) are profiled so that a rotational torque is applied to the shaft (8) by the axial compressive force of the spring (10) when the shaft (8) is within a range of rotational angles, relative to the casing (1), a member (2) is rotatably mounted within the casing (1), a space (A) between the movable member (2) and the casing (1) being filled with a viscous fluid (B), and a spring clutch (5) is connected between the movable member (2) and the spring carrier (4) such that the movable member (2) rotates with the shaft (8) in one direction of shaft rotation only. A hinge as claimed in claim 2, characterised in that the contacting faces of the cams (6,9) are profiled so that the rotational torque is applied to the shaft (8) in an initial stage of rotation of the shaft (8) relative to the casing (1).

Inventors: NAKAYAMA YOJIRO C O SUGATSUNE, OHSHIMA KAZUYOSHI C O SUGATSUN, NAKAYAMA, YOJIRO, C/O SUGATSUNE INDUSTRIAL CO.LTD., OHSHIMA,KAZUYOSHI, C/O SUGATSUNE INDUSTRIAL CO.LTD
Applicants: SUGATSUNE KOGYO, SUGATSUNE INDUSTRIAL CO., LTD.
Application year: 1990
Main classification: A47K13
IPC codes: E05D11, E05F3, A47K13