A MECHANISM FOR OPENING AND CLOSING TOILET SEAT AND COVER

Abstract: A detachable opening and closing structure for stool seat and cover, wherein a resistance mechanism is not actuated when opening the seat and cover, but turns them quickly within a predetermined range of angles and then operates slowly for closing, and an erection mechanism applicable preferably to such mechanism is provided further thereto. Accordingly, when opening the seat and cover, these can be handled lightly as in the case of normal seat and cover, and closed within a short time despite being loaded with a resistance. Shocks from the opening and closing mechanism to the stool side are relieved, thus preventing members from damage, loose work and the like. Further, it is not necessary to provide the erection mechanism separately from the opening and closing mechanism, a structure can be compact, the mechanism is detachable easily to simplify the maintenance work, and sanitary use is ensured.

Description: This invention relates to an opening and closing mechanism for the seat and cover which are provided on a stool. Description of the Prior Art For a flush toilet, a seat only or a seat with a closable cover is generally mounted, and that with the base end portion coupled to a stool body by a hinge mechanism is employed as the simplest structure. The hinge mechanism consists of base end portions of the seat and cover connecting to the stool body by a shaft such as pins or the like, and the seat and cover are coupled integrally or rotatably with the pins, thus rotating freely to a hinge part of the stool body. In the US-A-2 329 240 there has been described an opening and closing mechanism connecting at least one of a seat and a cover closably to a stool having a fitting shaft inserted in mounts provided on at least one base end of the seat and a cover and supported detachably. This known opening and closing mechanism further comprises a resistance mechanism for providing a turning resistance at least at the time when at least one of said seat and cover is closed. Additionally, this known opening and closing mechanism comprises a constraint mechanism for retaining the seat in an intermediate position, the constraint mechanism comprising a cam means fixedly mounted on the fitting shaft and a locking means engaging the cam means. However, in such a seat and cover working on a free rotation system, the seat and cover naturally fall shut when unhanded for closing and thus cause a loud sound when striking the stool body; therefore care should particularly be taken when using at night. Further, frequent shocks resulting on the stool body by the seat and cover may cause the hinge part to work loose, thus shortening the life of the product. SUMMARY OF THE INVENTION An object of the invention is to provide a opening and closing mechanism capable of realizing a damping function satisfactorily for bringing down the seat and cover from erected state. To solve the above-mentioned problem an opening and closing mechanism connecting at least one of the seat and the cover closably to a stool is provided, having fitting shafts inserted in mounts provided on at least one base end of the seat and the cover and supported detachably and a resistance mechanism for providing a turning resistance only at the time when at least one of said seat and cover is closed, characterized in that said opening and closing mechanism comprises a constraint mechanism for retaining at least one of the seat and the cover in the erected position and a power transmission mechanism for correcting a change in turning force through the period from the erected position to closing, which power transmission mechanism is provided by a combination of that fitting shaft and said resistance mechanism wherein said fitting shaft is inserted into an aperture of a joint member of said resistance mechanism. Improved embodiments of this solution are defined in subclaims 2 to 11. The embodiment according to claims 8 to 10 are able to additionally retain toilet seat or cover in its upright position whereas with the embodiment of claim 11 additionally the fitting shaft can be easily detached for maintenance purposes. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings represent a preferred embodiment of the invention. Fig. 1 and Fig. 2 show a state wherein a sanitary washing device B having a cleaning function is provided on a stool body A, and an opening and closing mechanism according to the invention is disposed within the casing. Fig. 3 is a plan view, partly cutaway, of the opening and closing mechanism of the invention; Fig. 4 is a view taken on line I - I of Fig. 3; Fig. 5 (a) is a front view of a fitting shaft; Fig. 5 (b) is a sectional view taken on line II - II of Fig. 5 (a); Fig. 6 is a sectional view showing the fitting shaft and a mount for seat and cover; Fig. 7 (a) is a view, partly cutaway, showing a casing installation of the opening and closing mechanism; Fig. 7 (b) is a plan view, partly cutaway, of the casing. Fig. 8 is a perspective view of a coil spring having a clutch function; Fig. 9 is a sectional view showing a joint behavior according to a rotation of the fitting shaft; Fig. 10 is a sectional view showing an arrangement of the fitting shaft and a locking cap; and Fig. 11 shows another embodiment of locking means for the fitting shaft. Further, Fig. 12 is an exploded perspective view showing a mounting of the seat and cover on the sanitary washing device; Fig. 13 is a longitudinal sectional view showing a main part of a mounting structure; Fig. 14 is a sectional view taken on line V - V of Fig. 13; Fig. 15 is a perspective view showing a locking piece portion of a bush; Fig. 16 is a sectional view showing a deformation of the locking piece due to an insertion of the fitting shaft. DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The embodiment relates to a construction wherein a sanitary washing device B having a cleaning function for the private parts is provided on a stool body A as shown in Fig. 1 and Fig. 2, an opening and closing mechanism is disposed within the casing, and a seat 1 and cover 2 are connected to the sanitary washing device B at left and right portions thereof respectively. A pair of mounts 1a, 2a connected to an opening and closing mechanism M are formed on each base end of the seat 1 and the cover 2, and the seat 1 and the cover 2 are connected to the opening and closing mechanisms M by means of the mounts 1a, 2a and fitting shafts 3. The fitting shaft 3 consists of a rod made of synthetic resin and a nose contracted as shown in Fig. 5 (a), and the section orthogonal to the line of axis is elliptic to have straight and curved profile as shown in Fig. 5 (b). Recesses 3a in point symmetry to the center of section are formed as a cam part on a peripheral surface of the portion inclined toward the nose from the axial center. Sectional forms of insertion holes 1b, 2b of the mounts 1a, 2a for the seat 1 and the cover 2 in which the fitting shafts 3 are inserted vary depending on a horizontal disposition of the mounts 1a, 2a as shown in Fig. 6. That is, when mounts 1a, 2a are located on the right side in Fig. 2, the sectional form of the insertion hole 1b on the seat 1 side is a circle with a circular face of the fitting shaft 3 as radius, as shown in Fig. 6 (a), (b), while the insertion hole 2b for the cover 2 has an elliptic section to which the fitting shaft 3 corresponds. When mounts 1a, 2a are located on the left side in Fig. 2, the fitting shaft 3 is fitted in the insertion hole 1b for the seat 1, and the insertion hole 2b for the cover 2 is circular in section as shown in Fig. 6 (c), (d). According to such sectional forms of the insertion holes 1b, 2b, the seat 1 rotates freely round the fitting shaft 3 on the right side, and the cover 2 rotates together with the fitting shaft 3, while the seat 1 rotates together with the fitting shaft 3, and the cover 2 rotates regardless of the fitting shaft 3 on the left side. The opening and closing mechanism M consists of a casing 4 fixed on a base B-1 of the sanitary washing device B. A support boss B-2 for receiving a fixing piece 4a provided on the casing 4 is formed on the base B-1 at a predetermined position as shown in Fig. 7 (a), and its upper end enters a hole 4b of the fixing piece 4a. An elastic sleeve 5 supporting a lower surface of the fixing piece 4a is provided on the support boss B-2, and the elastic sleeve 5 is available for shock-absorbing. The casing 4 has its fixing piece 4a fixed on the support boss B-2 by means of a screw 4c and a washer 4d. Accordingly, the opening and closing mechanism M can entirely be supported elastically on the sanitary washing device B by means of the sleeve 5 having a shock-absorber-function between the lower surface of the fixing piece 4a and the base B-1. Further, since the upper end of the support boss B-2 is inserted in the hole 4b of the fixing piece 4a, a positioning operation in assembling can be simplified. As will be apparent from Fig. 7 (b), the casing 4 has a double-tube structure with an annular inner wall 6. A slit 6a running axially of the casing 4 is provided at the upper and lower portions in a longitudinal section of the inner wall 6, and a salience 6b which is circular in longitudinal section is projected axially at the center of the inside end wall of the casing 4. Further, as shown in Fig. 3, a rotor 7 is disposed in the casing 4 which provides a resistance to a rotation of the seat 1 and the cover 2 which is transmitted from the fitting shaft 3, and a joint 8 for connecting the fitting shaft 3 to the opening and closing mechanism M is also disposed in the casing 4. The rotor 7 provides a resistance when the seat 1 and the cover 2 are closed, thus functioning as a resistance mechanism, enabling a damped closing operation. That is, the rotor 7 has a double-tube structure with a two-layer wall standing between an inner peripheral wall of the casing 4 and the inner wall 6, and filling up an inner peripheral side of the inner wall 6. A tubular rib 7a is formed at the center of the interior of the rotor 7 so as to be coaxial with the casing 4. An O-ring 7b is provided between the casing 4 and the joint 8, a closed space is provided between the inner peripheral wall of the casing 4 and inner and outer walls of the inner wall 6, and grease or the like is charged therein. The grease is charged entirely on the inner wall 6 and between the inner peripheral wall of the casing 4 and the rotor 7, and a viscosity of the grease functions as a resistance of a rotation of the rotor 7 to the casing 4. The joint 8 has its nose portion inserted in the rib 7a of the rotor 7, and the joint 8 and the rotor 7 are rotatable independently. The outside diameter of the rib 7a and the outside diameter on the nose side of the joint 8 are formed to be equal, and a portion joining with an end portion of the rib 7a is provided with metallic rings 9a, 9b. The rings 9a, 9b have outside diameters equal to that of the rib 7a, a coil spring 10 is fitted between a base end of the rib 7a and a halfway portion of the joint 8, and a junction through the coil spring 10 is utilized as a clutch mechanism. The coil spring 10 is wound counterclockwise (spirally counterclockwise centrally of the line of axis of the spring) as shown in Fig. 8 (a), and is incorporated in the opening and closing mechanism M in the left side in Fig. 2. A wire such as heat-treated steel or the like which constitutes the coil spring 10 is suitably flat in section. Further, the coil spring 10 wound clockwise (spirally clockwise centrally of the line of axis of the spring) as shown in Fig. 8 (b) is incorporated in the opening and closing mechanism M in the right side in Fig. 2. Thus, when raising the seat 1 and/or the cover 2, a rotation of the fitting shaft 3 will not be transmitted to the rotor 7 by providing the coil springs 10 on the opening and closing mechanisms M. That is, when the opening and closing mechanism M is located in the left side in Fig. 3, the fitting shaft 3 rotates clockwise when viewed from the center of the seat 1 and the cover 2, and the coil spring 10 is loaded with a working force counter to the winding direction of the coil spring 10. As a result, the coil spring 10 is expanded in its inner diameter, a transmission of the turning force between the joint 8 and the rotor 7 is collapsed due to slipping between the coil spring 10 and the rotor, and thus the rotation is not transmitted from the fitting shaft 3 to the rotor 7. On the other hand, when the opening and closing mechanism M is positioned in the right side in Fig. 2, the fitting shaft 3 rotates counterclockwise when viewed from the center of the seat 1 and the cover 2. The coil spring 10 is loaded with a working force which is counter to the winding direction of the coil spring, therefore due to an expansion of the inner diameter of the coil spring 10 a slip arises likewise, and the rotation cannot be transmitted. Fig. 9 (a) is a longitudinal sectional view of the joint 8 which is taken on line III - III of Fig. 3. An insertion hole 8a in which a nose portion of the fitting shaft 3 is inserted is formed axially on the joint 8. The insertion hole 8a has an opening sectional form whereby the fitting shaft 3 having an almost elliptic section can be turned freely by a predetermined angle round its axis. That is, since a pair of curved portions 8b having a form equal to that of a circular portion of the fitting shaft 3 and a pair of segmentary linear portions 8c are formed, the fitting shaft 3 is allowed to have a play of predetermined angle around the axis as shown in Fig. 9 (a) and (b). Accordingly, if the fitting shaft 3 rotates within the range of angles included in the play, the rotation of the fitting shaft 3 will not be transmitted to the joint 8. When linear portions of the fitting shaft 3 come in contact with the linear portions 8c of the insertion hole 8a (as shown in Fig. 9 (c), (d)), the joint 8 rotates together with the rotation of the fitting shaft 3. Further, a locking cap 11 for the fitting shaft 3 is detachably attached to the casing 4 so as to be coaxial with the joint 8. As shown in Fig. 3 and Fig. 4, the locking cap 11 consists of an annular member provided with a hook 11a engaging with a claw 4e projecting on a peripheral surface of the casing 4. As shown in Fig. 10 (a), a pair of locking pieces 12 for constraining a peripheral surface of the recess 3a of the fitting shaft 3, and roller pieces 12a incorporated rotatably therein for minimizing a wear of the contact face are contained within the locking cap 11. The locking pieces 12 have the base ends pivoted rotatably on the locking cap 11 and thus are rotatable in the direction indicated by an arrow in the drawing. A spring 13 for energizing the locking piece 12 to the peripheral of the fitting shaft 3 is connected thereto, and a rotation of the fitting shaft 3 is loaded with a resistance due to the energizing force. When the fitting shaft 3 is inserted into the joint 8 through the locking cap 11, the recess 3a of the fitting shaft 3 is set to a position corresponding to that of the roller pieces 12a of the locking pieces 12 of the locking cap 11, as shown in Fig. 3. As shown in Fig. 5 (b), the recess 3a of the fitting shaft 3 has the linear portions 3b and the curved portions 3c, and the linear portions 3b are sandwiched between the roller pieces 12a as shown in Fig. 10. Thus, when the linear portions of the fitting shaft 3 face to the roller pieces 12a in position, the rotation of the fitting shaft 3 is constrained. Accordingly, the locking cap 11 may function as a constraint mechanism for holding the seat 1 at a position where the seat 1 should be erected. Another opening and closing mechanism M including the aforementioned elements is disposed in the right side in Fig. 2. In this case, the relationship between the insertion holes 1b, 2b of the mounts 1a, 2a for the seat 1 and the cover 2 and the fitting shaft 3 is described with reference to Fig. 6 (a) and (b). Since the cover 2 will not fall in the direction in which the cover is closed on an empty weight even in case it is placed against a tank of the stool, the constraint mechanism is not required, and hence the locking pieces 12 and the roller pieces 12a are not incorporated in the locking cap 11. However, other mechanisms are all the same as those on the left side. In the above-described construction where the cover 2 only is erected, the fitting shaft 3 is fitted in the insertion hole 2b of the mount 2a in the right side as shown in Fig. 6 (b), while it is fitted loosely therein on the left side, therefore the fitting shaft 3 of the opening and closing mechanism M in the right side rotates together with the cover 2. That is, in erecting the cover 2 only, only the opening and closing mechanism M in the right side contributes to actuation, and the cover 2 is rotatable around the fitting shaft 3 connected to the opening and closing mechanism M in the left side. On the other hand, the fitting shaft 3 for erecting the seat 1 from the closed state rotates as shown in Fig. 9 and Fig. 10. Fig. 10 (a) and Fig. 10 (b) indicate the case where the seat 1 is closed, and the linear portion 3b of the fitting shaft 3 is vertical. When the seat 1 is erected from the closed state, the fitting shaft 3 rotates clockwise in Fig. 9 (a) and Fig. 10 (a). In this case, the recess 3a of the fitting shaft 3 pushes the locking pieces 12 and the roller pieces 12a to continue the turning of the fitting shaft 3, and the nose portion inserted in the joint 8 changes the posture as shown in Fig. 9 (b). That is, since the insertion hole 8a of the joint 8 has a play to the fitting shaft 3, the rotation will not be transmitted to the joint 8 until the linear portion 3b of the fitting shaft 3 comes in contact with the linear portion 8c of the insertion hole 8a as shown in Fig. 9 (b). Accordingly, such load as is necessary for the recess 3a to rotate against the spring 13 is sufficient for the cover 2 to start opening, thus ensuring light handling. When the seat 1 is raised further, the turning force is transmitted to the joint 8, which is ready for turning. On the other hand, the coil spring 10 of the opening and closing mechanism M in the left side is wound counterclockwise when viewed from the center of the seat 1. Accordingly, since the joint 8 rotates clockwise, the coil spring 10 is loaded with a working force which is counter to the direction in which it is wound in a circumferential direction concurrently with a rotation of the joint 8. As a result, the inner diameter of the coil spring 10 becomes large, a fitting-in degree to the joint 8 and the rotor 7 decreases, and the transmission of the turning force therebetween is stopped. Thus, by utilizing a deformation of the coil spring 10, the joint 8 idles in the casing 4, and the fitting shaft 3 will not be loaded with a resistance caused by the casing 4 and the rotor 7. Accordingly, no resistance will work when the seat 1 is opened, thus enabling an easy operation to erect the seat 1 in position. In the opening and closing mechanism M on the right side, the fitting shaft 3 is rotatable in the insertion hole 1b of the mount 1a as shown in Fig. 6 (a), therefore it rotates freely at the time when the seat 1 is turned. When the seat 1 is erected, the roller pieces 12a of the locking pieces 12 of the locking cap 11 come in contact with the linear portions 3b of the fitting shaft 3 as shown in Fig. 10 (c). The roller pieces 12a hold the linear portions 3b therebetween with energizing force of the spring 13, and constrain a rotation of the fitting shaft 3 by means of the moment of rotational force of the seat 1. Thus the seat 1 is retained at its erected position and ready for self-supporting. Accordingly, the seat 1 can stand still at a proper angle of erection. When closing the seat 1, the seat 1 is to be depressed with force enough to release the constraint of the fitting shaft 3 due to the roller pieces 12a. In this case, the fitting shaft 3 rotates counterclockwise in Fig. 9 (d) and Fig. 10 (c). The seat 1 moves quickly, without being subjected to a resistance caused by the casing 4 and the rotor 7, down to a predetermined angle from the point of erection according to the existence of a play between the joint 8 and the fitting shaft 3. That is, through the period from the state of Fig. 9 (d) to that of (c), the fitting shaft 3 rotating together with the seat 1 idles in the joint 8 because of the form of the insertion hole 8a in the joint 8. As shown in Fig. 9 (c), a rotation from the fitting shaft 3 is transmitted to the joint 8 when the linear portions 3b of the fitting shaft 3 come in contact with the linear portions 8c of the insertion hole 8a. Accordingly, in a domain with angle α shown in Fig. 9 (c), the seat 1 moves in a manner of a natural fall and turns quickly in the direction of closing without being subjected to a resistance. Further, after reaching the state of Fig. 9 (c), the joint 8 is rotated counterclockwise by means of the fitting shaft 3. In this case, the coil spring 10 disposed against the rotor 7 receives a working force in the winding direction from a peripheral surface of the joint 8. Accordingly, the coil spring 10 is deformed to have the inner diameter reduced, and pushes strongly each fitted portion of the joint 8 and the rotor 7, and thus a turning force can be transmitted from the joint 8 to the rotor 7. When the rotor 7 turns in the casing 4, a resistance caused by the grease enclosed therein works. As a result, the seat 1 turns quickly in the domain with angle α , while the seat 1 is decelerated thereafter due to the resistance to an approximately constant low speed, and then falls slowly to reach the upper surface of the stool body A. Thus, when closing the seat 1, it rotates quickly in a predetermined range of angle from the erected state and falls slowly thereafter. Accordingly, the time for closing the seat 1 is shortened as compared with a construction wherein the resistance works always through closing motion. In the movement of the seat 1 to reach the surface of the stool body A, since the resistance caused by the casing 4 and the rotor 7 works, the seat 1 can move slowly. Thus, a shock will not occur on the seat 1 and hence loud sound will never be produced, and a smooth and gentle operation can be conducted consequently. Further, when raising both the seat 1 and the cover 2 together, a similar operation to that in the above description is realized according to a function of the opening and closing mechanisms M. Needless to say, the seat 1 assumes a similar behavior to the above description. The cover 2 performs a damping action for closing in the right side opening and closing mechanism M. The cover 2 has the fitting shaft 3 fitted in the insertion hole 2b of the mount 2a as shown in Fig. 6 (b), and the seat 1 is rotatable with reference to the fitting shaft 3 as shown in Fig. 6 (a). Thus, the right side opening and closing mechanism M controls only to operation of the cover 2, and its behavior is exactly the same as that for the seat 1. That is, when raising the cover 2, a resistance is removed by expansion of the inner diameter of the coil spring 10, and when closing, it moves quickly at first but is subjected to a resistance caused by the casing 4 and the rotor 7 before running toward the seat 1, thus closing gently. Further, in case the seat 1 only is closed while the cover 2 remains erected, the opening and closing mechanism M in the left side operates. Since the fitting shaft 3 is rotatable with reference to the insertion hole 1b in the right side of the seat 1 as shown in Fig. 6 (a), the right side opening and closing mechanism M does not interlock with the operation of the seat 1. It goes without saying that the seat 1 may be related to interlocking with the opening and closing mechanism M in the right side, and the cover 2 may be related to interlocking with that in the left side because of the relationship between the fitting shaft 3 and the insertion holes 1b, 2b for the seat 1 and the cover 2. Further, the fitting shaft 3 has its end surface constrained by a projection 2c provided on the cover 2 as shown in Fig. 3 and Fig. 4. Still further, the opening and closing mechanism M is fixed on the base B-1 by means of the sleeve 5 having a damping function. Accordingly, shocks and so on due to the operation of the seat 1 and the cover 2 are absorbed, and vibrations affecting the sanitary washing device B can be damped. Thus, an impact on the equipments provided on the sanitary washing device B is reduced, and a loose work of members can be eliminated thereby. Another embodiment of the construction of the constraint mechanism is illustrated in Fig. 11. The locking cap 11 is provided with a pair of locking arms 120 at the inner periphery thereof. A slit 130 separates each locking arm 120 from the inner body of the locking cap 11, so that the locking arms 120 may be elastically deformed in the radial direction. The locking arm 120 has an engaging portion 120a at the inner side of the distal end thereof which engages the linear portion 3b of the fitting shaft 3 shown in Fig. 16 (a) to regulate the rotation of the fitting shaft 3. When the fitting shaft 3 is forced to rotate counterclockwise in Fig. 11 (a), the linear portion 3b pushes the engaging portion 120a to deform the locking arm 120 outwardly, and subsequently the fitting shaft 3 rotates without being constrained due to the locking arms 120 as shown in Fig. 11 (a). On the other hand, when the fitting shaft 3 rotates clockwise in Fig. 11 (b), the curved portion 3c pushes the distal inner end portion of the locking arm 120, so that the fitting shaft 3 may rotate and move into the state of locking shown in Fig. 11 (a). Such a construction of the constraint mechanism can perform locking function for the fitting shaft 3 as well as that in the embodiment shown in Fig. 10. Another mode than the above-described embodiment may be employed as a structure for providing the seat 1 and the cover 2. The embodiment is described with reference to Fig. 12 to Fig. 16. In Fig. 12, the seat 1 and the cover 2 are fitted rotatably by inserting fitting shafts 30 into pivoting holes 51a of a casing 51 of the sanitary washing device. The seat 1 as well as the mounts 1a is made of synthetic resin such as ABS or the like, and a bush 40 for supporting the fitting shaft 30 thereon is unified with the mount 1a. Since a synthetic resin has mechanical strength, the bush 40 can be incorporated in the hole 1b provided on the mount 1a by use of insertion works. As shown in Fig. 14, a plurality of ridges 40a are provided on the peripheral surface of the bush 40, and are engaged in the hole 1b, thereby constraining a rotation of the bush 40. Further, a side of the bush 40 facing to the center of the seat 1 forms an open cavity 40b, and an insertion hole 40c of the fitting shaft 30 communicates with the cavity 40b. A tubular portion 50 is formed integrally with the cavity 40b so as to be coaxial with the insertion hole 40c. Four slits 50a are provided axially on a nose of the tubular portion 50 as shown in Fig. 15, and a pair of slits with a minor length in the circumferential direction are made to function as locking pieces 60 for the fitting shaft 30. The locking pieces 60 are positioned opposite each other radially, and a projection 60a is provided on the inner periphery of each nose protrusively toward the center. On the other hand, the fitting shaft 30 is provided with a flange 30a at one end thereof which is seated on an end surface of the bush 40, and a groove 30c is formed in the circumferential direction on a the shaft part 30b near the flange 30a. The groove 30c is formed at a position where the projection 60a of the locking piece 60 may come in when the flange 30a is seated on the end surface of the bush 40 as shown in Fig. 13. The nose of the fitting shaft 30 passes through the bush 40 to reach the hole 2b provided on the cover 2, and the fitting shaft 30 is supported within the hole 51a of the washing device 51. In the above-described construction, the mounts 1a, 2a are set in position, and the fitting shaft 30 is inserted in the bush 40 as shown in Fig. 16 (a) to couple the seat 1 and the cover 2 to the washing device 51. In this case, the locking piece 60 is deformed elastically by the shaft part 30b of the fitting shaft 30 to expand outward as shown in Fig. 16 (a) and (b) (a sectional view taken on line VI - VI of Fig. 15 (a)). A relief is prepared with a nose of the projection 60a of the locking piece 60 as a tapered face 60b so as to allow smooth insertion of the fitting shaft 30. When the nose of the fitting shaft 30 comes into the hole 51a of the washing device 51 and the flange 30a is seated on an end surface of the bush 40, the projection 60a of the locking piece 60 engages with the groove 30c as shown in Fig. 13. Accordingly, the fitting shaft 30 is regulated against axial movement by means of the locking piece 60, and thus can be prevented from ejection. As described above, the seat 1 and the cover 2 can be coupled simply by inserting the fitting shaft 30 in the bush 40 provided with the locking piece 60 to be deformed elastically. Thus, a mechanical means such as a screw or the like is not required, and hence it is ready for installation simply and manufactured very easily. When removing off the fitting shaft 30, it can be detached simply by raising the flange 30a by means of a screwdriver or the like and disengaging the projection 60a and the groove 30c. Accordingly, it is easy to handle and the stool is clean to ensure a comfortable use at all times. In the above-described embodiment, the seat and the cover are coupled to the washing device. In addition, the fitting structure according to this invention can be applied also to directly couple the seat and cover to the stool body where these are coupled directly by using a hinge mechanism. Further, the fitting structure can be applied likewise to a stool provided with the seat only. The opening and closing mechanism for the seat and cover according to this invention may be applied not only to the stool having a sanitary equipment as exemplified in the above-described embodiment but also to a stool having various forms.

Claims: An opening and closing mechanism (M) connecting at least one of a seat (1) and a cover (2) closably to a stool (A), having fitting shafts (3; 30) inserted in mounts (1a, 2a) provided on at least one base end of the seat (1) and the cover (2) and supported detachably and a resistance mechanism (4, 6, 7, 8, 9a, 9b, 10) for providing a turning resistance only at the time when at least one of said seat (1) and cover (2) is closed, characterized in that said opening and closing mechanism (M) comprises a constraint mechanism (12, 120) for retaining at least one of the seat (1) and the cover (2) in the erected position and correcting a change in turning force through the period from the erected position to closing, which power transmission mechanism is provided by a combination of that fitting shaft (3) and said resistance mechanism (6, 7, 8, 9a, 9b, 10) wherein said fitting shaft (3) is inserted into an aperture (8a) of a joint member (8) of said resistance mechanism (6, 7, 8, 9a, 9b, 10). Mechanism according to claim 1, wherein a means (3b, 8b, 8c) for providing an interplay (backlash) (α) is interposed between said fitting shaft (3) and said aperture (8a) and allows at least the seat (1) or the cover (2), respectively, to be brought into a position where it tends to fall down or a position where it may be raised up easily. Mechanism according to claim 1 or claim 2, which comprises a viscosity resistance device (grease between 4 and 6) cooperating with a clutch means (10) of the resistance mechanism (4, 6, 7, 8, 9a, 9b, 10). Mechanism according to claim 3, wherein the viscosity resistance device comprises a rotor (7) and parts (6) of a casing (4) fixed to the stool (A), grease being interposed between said rotor (7) and said parts (6) of the casing (4). Mechanism according to claim 4, wherein in the power transmission means the clutch means comprises a coil spring (10) interposed between said rotor (7) and said joint member (8), which spring (10) disconnects said rotor (7) and said joint member (8) when the corresponding seat (1) or cover (2), respectively, is moved from the closed to the opened position. Mechanism according to anyone of the preceding claims wherein a resistance mechanism is provided each for the cover (2) and the seat (1). Mechanism according to claim 6, wherein means (1a, 1b, 2a, 2b - left end right side - 3 - Fig. 6) are provided which allow the cover (2) and the seat (1) to be turned separately. Mechanism (M) according to anyone of the preceding claims wherein the constraint mechanism (12, 120) retains also at least one of the seat (1) and the cover (2) in the closed position, and the constraint mechanism (12, 120) comprises a cam means (3a, 3b, 3c) fixedly mounted on the fitting shaft (3) and a locking means (12, 120) engaging the cam means (3a, 3b, 3c) in both end positions of the seat (1) or cover (2), respectively, the locking means (12, 120) being a spring loaded device with operating surfaces being adapted to the caming surfaces of the cam means (3a, 3b, 3c). Mechanism according to claim 8, wherein the locking means (12) comprises a cap (11) having a pair of locking pieces (12) which are pivotably mounted in the cap (11) and loaded each by a corresponding spring (13). Mechanism according to claim 8, wherein the locking means (120) comprises a locking cap (11) having a pair of locking arms (120), each of the arms (120) being separated by a corresponding slit (130) from the inner periphery of the cap (11) to be elastically deformable in the radial direction and each having an engaging portion (120a) at the distal end thereof. Mechanism according to anyone of the preceding claims wherein a synthetic resin made bush (40) is provided on each of said mounts (1a), each fitting shaft (30) being inserted through a corresponding bush (40), each bush (40) having a locking piece (60) which can elastically be deformed radially around a line of insertion of the corresponding fitting shaft (30) and in that a groove (30c) being provided on a peripheral surface of each fitting shaft (30) which groove (30c) engages with the corresponding locking piece (60).

Inventors: FUJIE, YUJI, KADOMATSU, SIGENARI, KAWAMOTO, MASANOBU, KOBAYASHI, KEIICHI KOKURA PLANT NO. 2, TOTO LTD., MORIWAKI, MASAZUMI KOKURA PLANT NO. 2, TOTO LTD.
Applicants: NIFCO INC., TOTO LTD.
Application year: 1989
Main classification: A47K13
IPC codes: A47K13, E05D11, E05F3