Opening-closing device of western style toilet seat and seat cover

An opening-closing device for a Western style toilet seat and seat cover is disclosed, in which a pair of hinge cases are mounted at a predetermined spacing at the rear upper end of a Western style toilet bowl; in either of the pair of hinge cases a rotating shaft for the seat and a rotating shaft for the seat cover are rotatably mounted; on the rotating shaft for the seat in either hinge case, the seat mounting section is rotatably mounted, and on the rotating shaft for the seat cover in the hinge case, the seat cover mounting section is rotatably mounted; and a rotation control mechanism is mounted on the rotating shaft for the seat and the rotating shaft for the seat cover, to thereby prevent sudden drop of the seat and seat cover, At this time, the rotation control mechanism may be a cam mechanism using a compression spring, a torsion spring, a rotation camper, or a friction mechanism. Furthermore, the cam mechanism may be comprised of a stationary cam fixed on a partition wall provided in the hinge case with the rotating shaft inserted in the center, a rotating-sliding cam which is disposed oppositely to the stationary cam and can slide in the axial direction of the rotating shaft while rotating together with the rotating shaft, and a compression spring for pressing the rotating-sliding cam towards the stationary cam side.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an opening-closing device suitable for use 
particularly in opening and closing Western style toilet seat and seat 
cover. 
2. Description of the Related Art 
As this type of opening-closing device, a pair of opening-closing devices 
having a rotating shaft fitted with a rotation control means have been 
known. These devices are mounted at a specific spacing at the rear upper 
end of the toilet bowl in order to prevent abrupt drop of the seat and 
seat cover. One of the opening-closing devices is for the toilet seat, 
while the other is for the seat cover. In the prior art opening-closing 
device, a mounting section of the seat is secured on one mounting shaft 
portion of the rotating shaft and at the same time the mounting section of 
the seat cover is rotatably supported. Also on the mounting shaft portion 
of the other rotating shaft, the other mounting section of the seat is 
rotatably supported and the mounting section of the seat cover is secured, 
so that either opening-closing device will operate when either the seat or 
the seat cover is opened or closed. 
In the prior art opening-closing device, the mounting shaft portion of the 
rotating shaft to be coupled to the mounting section of the seat and the 
seat cover and the mounting pin of the seat and seat cover to be inserted 
into an irregular mounting hole provided axially in the rotating shaft are 
irregular shafts of approximately elliptical section which are formed by 
cutting off their both sides. The irregular shaft is fixed in one 
irregular hole of the seat and seat cover mounting section, and inserted 
into a round hole. Therefore there arises such a disadvantage that the 
seat and seat cover are likely to vibrate more or less when opened or 
closed, and since the opening-closing device with the rotation control 
means acts only on one side of the seat and seat cover mounting section. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an opening-closing 
device which ensures well-balanced operation of the seat and seat cover. 
It is another object of the present invention to provide an opening-closing 
device so constituted as to prevent vibration when the seat and seat cover 
is opened or closed. 
It is further another object of the present invention to provide an 
opening-closing device capable of imparting clear-cut outside appearance 
when the device is mounted on a Western style toilet bowl. 
To accomplish the above-described objects, a pair of hinge cases are 
mounted at a predetermined spacing at the rear upper end of the Western 
style toilet bowl; in either of the pair of hinge cases the rotating shaft 
for the seat and the rotating shaft for the seat cover are rotatably 
mounted separately; on the rotating shaft for the seat in either hinge 
case, the seat mounting section is rotatably mounted; on the rotating 
shaft for the seat cover in the hinge case, the seat cover mounting 
section is rotatably mounted; and a rotation control means is mounted on 
the rotating shaft for the seat and the rotating shaft for the seat cover, 
to thereby prevent sudden drop of the seat and seat cover. 
According to the present invention, a pair of hinge cases are mounted at a 
predetermined spacing at the rear upper end of the Western style toilet 
bowl; in either of the pair of hinge cases, a pair of rotating shafts for 
the seat and the seat cover are rotatably mounted; a rotation control 
means is provided on only one of the rotating shafts for the seat and the 
seat cover; and the seat and seat cover mounting sections are rotatably 
mounted on the rotating shaft on which the rotation control means is 
provided, and on the other rotating shaft. 
It is to be noticed that, in the present invention, the rotation control 
means may be a cam mechanism provided with a compression spring. 
Furthermore, the cam mechanism may be comprised of a stationary cam fixed 
on a partition wall provided in the hinge case with the rotating shaft 
inserted in the center, a rotating-sliding cam which is disposed 
oppositely to the stationary cam and can slide in the axial direction of 
the rotating shaft while rotating together with the rotating shaft, and a 
compression spring for pressing the rotating-sliding cam towards the 
stationary cam side. 
Furthermore, in the present invention, the rotation control means may be a 
torsion spring, a rotation damper, or a friction mechanism. 
Furthermore, in the present invention, a pair of hinge cases, when mounted 
at the rear upper end of the toilet bowl, can be releasably mounted on a 
hinge holder mounted at the rear upper end of the toilet bowl. 
At this time, in the present invention, the hinge case, when removably 
mounted to the case holder, may be comprised of a leg which is releasably 
engaged with the case holder for holding the hinge case to restrict the 
vertical movement of the hinge case fitted in the case holder, and a 
locking piece inserted between the hinge cases in the case holder for 
restricting the lateral movement of the hinge case fitted in the case 
holder. 
Furthermore, in the present invention, when the hinge case is removably 
installed to the case holder, the hinge case can be unitarily formed with 
the leg and fitted in the case holder, and then the locking piece can be 
inserted between the hinge cases to thereby restrict the lateral movement 
of the hinge case.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
One embodiment of the present invention is shown in the accompanying 
drawings. In FIGS. 1 to 3, reference numerals 1, 1 denote hinge cases of 
opening-closing devices A, A; and numeral 2 refers to a case holder in 
which a pair of hinge cases 1, 1 are removably housed. On both sides of 
the case holder 2, there are provided a pair of seat rotating shafts 3, 3 
protruding from one side of the hinge cases 1, 1 and a pair of insertion 
holes 2a, 2b into which seat cover rotating shafts 4, 4 are inserted. 
The right and left opening-closing devices A, A are the same in internal 
construction; therefore only the left opening-closing device will be 
explained. The hinge case 1 of the left opening-closing device A is 
provided with a first mounting hole 5 for a seat rotating shaft 3 and a 
second mounting hole 6 for a seat cover rotating shaft 4. In these 
mounting holes 5 and 6, the seat rotating shaft 3 and the seat cover 
rotating shaft 4 are rotatably mounted. The rotating shafts 3 and 4 are 
provided with rotation control means 7 and 8. The rotating shafts 3 and 4 
are the same in shape and construction and also the rotation control means 
7 and 8 the same in shape and construction as described later. Only the 
difference lies in the shape of the stationary cam. Hereinafter, 
therefore, the seat rotating shaft 3 and the rotation control means 7 for 
the rotating shaft 3 will be described. 
In FIGS. 4 to 8, a portion of the rotating shaft 3 which protrudes from the 
hinge case 1 is an irregular mounting shaft portion 3a having an 
approximately elliptical section formed by cutting its both sides off. The 
rotating shaft 3 has, in a portion housed in the hinge case 1, a 
large-diameter portion 3b at the inlet area of the hinge case 1 and a 
small-diameter portion 3c having an approximately elliptical section 
formed by cutting its both sides continuously to the large-diameter 
portion 3b. The rotating shaft 3 is supported at the large-diameter 
portion 3b on a bearing in the inlet of the first mounting hole 5 formed 
through the hinge case 1, and is rotatably mounted in the hinge case 1. An 
O-ring 9 is fitted in a peripheral groove 3d provided in the outer 
periphery of the large-diameter portion 3b. 
Within the first mounting hole 5 is mounted the rotation control means 7 of 
the rotating shaft 3 comprising a cam mechanism. The constitution of the 
rotation control means 7 is as described below. 
First, a plurality of engaging holes 5c are provided in a partition wall 5a 
formed in the first mounting hole 5. In the engaging holes 5c an engaging 
projection 10a projecting from one side of the partition wall 5a is 
inserted and fixed to prevent rotation of the stationary cam 10. On the 
other side of the stationary cam 10 is formed a cam portion 11 which 
consists of a convex portion 11a and a concave portion 11b, and the 
small-diameter portion 3c is rotatably inserted into the insertion hole 5b 
provided in the center. 
Oppositely to the cam portion 11 of the stationary cam 10 is mounted a 
rotating-sliding cam 12. The rotating-sliding cam 12 is rotatable and 
slidable together with the rotating shaft 3 with the small-diameter 
portion 3c of the rotating shaft 3 inserted and locked in an irregular 
hole 12a formed in the center of the cam portion 11. A convex portion 12b 
is provided in a position in which the rotating-sliding cam 12 faces the 
cam portion 11 of the stationary cam 10. 
Between the rotating-sliding cam 12 and the large-diameter portion 3b of 
the rotating shaft 3, a compression spring 13 wound over the 
small-diameter portion 3c is elastically mounted, constantly pressing the 
rotating-sliding cam 12 toward the stationary cam 10 side. For the 
compression spring 13, a plate spring is also usable. 
On the side where the rotating shaft 3 is mounted through the partition 
wall 5a, a mounting screw 14 is installed through a lock plate 14a, 
thereby preventing accidental axial removal of the rotating shaft 3 from 
the first mounting hole 5. Numeral 14b denotes a washer. 
The cam portion 11 of the stationary cam 10 used in the rotation control 
means 7 for the seat rotating shaft 3 and the cam portion 11 of the 
stationary cam 10 used in the rotation control means 8 for the seat cover 
rotating shaft 4 differ only in the inclination angle mainly of the 
concave and convex portions 11b and 11a and make no big difference in 
shape, particularly in the shape of their convex portion 11a and the cam 
portion 11 as shown in FIGS. 9 to 11. This is chiefly due to a difference 
in weight between a seat 19 and a seat cover 20 and a difference in the 
feeling of operation required (FIGS. 12 to 14). 
Next, a means for installing and removing the case holder 2 of the hinge 
cases 1, 1 will be explained. As shown in FIGS. 12 to 14, first the hinge 
cases 1, 1 are inserted from under the case holder 2, with the mounting 
shaft portions 3a and 4a of the seat and seat cover rotating shafts 3 and 
4 protruded outwards from the insertion holes 2a, 2b provided in the both 
sides. 
Next, a locking piece 17 is inserted into the space between the hinge cases 
1, 1 through the lower middle part of the case holder 2. Furthermore, 
fixing portions 18a, 18a of the legs 18, 18 consisting of screw rods are 
similarly inserted from both sides under the case holder 2, and at the 
same time an engaging projecting portion 18c is fitted in the engaging 
groove 1a. Then, protruding keys 17a and 18b provided on the front and 
rear sides are fitted in keyways 2c provided in the front and rear of the 
lower inner periphery of the case holder 2. 
Now the mounting of the hinge cases 1, 1 to the case holder 2 has been 
completed. When the rotating shafts 3 and 4 are protruded out of the 
insertion holes 2a, 2b in both sides of the case holder 2 in mounting the 
hinge cases 1, 1 to the case holder 2, it is advised that the case holder 
2 be secured to the mounting sections 19a, 19a and 20a, 20a of the seat 19 
and the seat cover 20. In this case, irregular mounting holes of the 
mounting sections which fit to the shape of the mounting shaft portions 
3a, 3a and 4a, 4a of the rotating shafts 3 and 4 are provided in the 
mounting sections 19a, 19a and 20a, 20a of the seat 19 and the seat cover 
20, and also the mounting sections 19a, 19a and 20a, 20a are secured to 
both the pair of rotating shafts 3 protruded from the hinge cases 1, 1 and 
the rotating shaft 4 for the seat cover. Therefore when the seat 19 and 
the seat cover 20 are opened and closed, the seat rotating shaft 3 and the 
seat cover rotating shaft 4 of the right and left opening-closing devices 
A, A rotate. The hinge case 1 can be removed from the case holder 2 by 
reversing the procedure described above. 
Next, holding by hand the case holder 2 mounted with the hinge cases 1, 1 
fitted with the seat 19 and the seat cover 20, the legs 18, 18 are 
inserted into mounting holes 21a provided in the toilet bowl 21 and 
fastened by a nut 22, thus completing the installation of the seat 19 and 
the seat cover to the toilet bowl 21 (FIG. 15) 
Next, operation of the opening-closing device A will be explained. As shown 
in FIG. 1, when the seat 19 is in a closed state as indicated by an 
imaginary line, the convex portion 12b of the rotating-sliding cam 12 
which constitutes the cam mechanism of the seat rotation control means 7 
shown in FIGS. 6 and 7 is in contact with the convex portion 11a of the 
cam portion 11 of the stationary cam 10. In this state, the compression 
spring 13 is fully compressed. When the seat 19 is opened from this state, 
the rotating shaft 3 rotates through the irregular mounting shaft portion 
3a which is engaged with the mounting section 19a. As shown in FIG. 8, the 
convex portion 12b of the rotating-sliding cam 12 which rotates in the 
same direction as the rotating shaft 3 turns from the convex portion 11a 
down to the concave portion 11b of the cam portion 11 of the stationary 
cam 10, sliding toward the stationary cam 10 side. In the present 
embodiment, as shown in FIG. 11, the toilet seat inclines reversely from 
the opening angle of 90 degrees, being braked. 
When the seat 19 is closed from its opened position, the cam mechanism of 
the rotation control means 7 turns in the reverse direction of the 
above-described operation. As shown in FIG. 11, when the convex portion 
12b of the rotating-sliding cam 12 turns from the closed angle of about 90 
degrees to change the contact position from the concave portion 11b of the 
cam portion 11 of the stationary cam 10 against the elastic force of the 
compression spring 13, there is produced resistance. By the presence of 
this resistance there occurs a reverse torque which cancels the turning 
moment of the seat 19, thus checking abrupt closing of the seat 19. In the 
present embodiment, from a closing angle of about 25 degrees the seat 
tends to tilt slightly quickly. To prevent this the brake is applied to 
the seat. From 20 degrees the inclination becomes gentle, allowing the 
seat to close slightly quickly. 
FIG. 16 shows another embodiment of the opening-closing device to be 
mounted within the case holder. In the hinge case 30 of the 
opening-closing device B of the present embodiment, a rotation control 
means 32 for controlling the rotation of the rotating shaft 31 which 
rotates with the opening-closing operation of the seat cover is composed 
only of a torsion spring 32a. The internal structure of the rotation 
control means for the seat, being the same as that for the seat cover, 
will not be illustrated. 
FIG. 17 shows further another embodiment of the opening-closing device to 
be mounted within the case holder. Within a hinge case 35 of the 
opening-closing device C of the present embodiment, a rotation control 
means 37 for controlling the rotation of a rotating shaft 36 which rotates 
with the opening-closing operation of the seat cover is composed of a 
rotation damper 37a. The internal structure of the rotation control means 
for the seat, being the same as that for the seat cover, will not be 
illustrated. 
FIG. 18 shows further another embodiment of the opening-closing device to 
be mounted within the case holder. Within a hinge case 40 of the 
opening-closing device D of the present embodiment, a rotation control 
means 42 for controlling the rotation of a rotating shaft 41 which rotates 
with the opening-closing operation of the seat cover is composed of a 
friction mechanism 42a which comprises a friction plate 43 to be pressed 
against a partition wall 40a, a spring washer 44, and a thrust washer 45. 
It should be noted that the constitution of the friction mechanism 42a is 
not limited to that of the present embodiment. The internal structure of 
the rotation control means for the seat, being the same as that for the 
seat cover, will not be illustrated. 
FIGS. 19 and 20 show further another embodiment of the opening-closing 
device. In the opening-closing device E of the present embodiment, 
according to the drawings, the hinge case 45 and the leg 46 are unitarily 
formed; a pair of hinge cases 45are inserted in the case holder 48 as 
shown in the embodiment previously shown, with a projecting key 45a formed 
on the hinge case 45 fitted in a keyway 48a; in a space located between 
the hinge cases 45, 45 a lockding piece 47 is mounted by pressing; and 
furthermore projecting keys 47a formed at the front and rear sides are 
fitted in keyways 48a, thereby securing the hinge cases 45, 45 in the case 
holder 48. 
The present embodiment, therefore, has the advantage that the hinge cases 
45, 45 can easily be mounted in the case holder 48.