Rotary damper

In a rotary damper capable of being easily assembled by reducing the remaining air inside an accommodation portion and reducing the non-uniformity of damping torque, a center shaft 73 is provided in the center of a fixing and supporting member 71, an inner cylinder wall 63 into which the center shaft 73 is inserted rotatably is provided in a driven rotation member 61, an O ring 81 which prevents the leakage of viscous fluid 101 from between the driven rotation member 61 and the fixing and supporting member 71 is provided, a first path 70 which enables the accommodation portion 91 to communicate with its outside is provided between the center shaft 73 and an inner circumference face of the inner cylinder wall 63, and a hole 63c which allows the bottom side of the O ring 81 inside the accommodation portion 91 to communicate with the first path 70 is provided in the driven rotation member 61.

TECHNICAL FIELD

The present invention relates to a rotary damper for damping the relative rotation of a driven rotation member and a fixing and supporting member which holds the driven rotation member to be freely rotatable by using viscous resistance of a viscous fluid.

BACKGROUND ART

There is a known rotary damper including a driven rotation member integrally formed with a rotation portion such as a gear or a rack which is engaged with a driving member, a fixing and supporting member which holds the driven rotation member rotatably, an accommodation portion, for example, in the shape of a circle, which is formed between the fixing and supporting member and the driven rotation member, a sealing member which seals an end of an outer circumference of the accommodation portion, so that the driven rotation member and the fixing and supporting member can be relatively rotated, and a viscous fluid which is stored in the accommodation portion and damps the relative rotation of the driven rotation member and the fixing and supporting member (for example, see Patent Document 1).

The rotary damper includes an opening (hole), which enables the accommodation portion to communicate with the atmosphere, in the center of the fixing and supporting member. The rotary damper prevents air from being collected in the accommodation portion at a time when the driven rotation member and the fixing and supporting member are assembled for easy assembly and prevents air from being mixed in the viscous liquid for maintaining the precision of torque.

However, since there is not a preventive plan for the leakage of the viscous liquid from the opening (hole), that is, the opening (hole) is not closed, when the rotary damper is used at a high temperature, the viscous liquid may leak from the opening (hole).

Thus, a rotary damper in which an opening (hole) which enables an accommodation portion to communicate with the atmosphere is not provided is proposed with consideration of the leakage of the viscous fluid from the opening (hole) (for example, see Patent Documents 2 to 5).

In addition, a rotary damper having a concave portion in which a convex portion of a casing fits at the center of the lower side and an air discharge path, one side of which is open for the concave portion of a rotation body and the other side of which is open for an outer circumference face of the rotation body in the rotation body rotatably disposed inside the casing filled with the viscous fluid is proposed (for example, see Patent Document 6).Patent Document 1: Japanese Registered Utility Model No. 2603574Patent Document 2: Japanese Examined Utility Model Registration Application Publication No. 1-37236Patent Document 3: Japanese Patent No. 3421484Patent Document 4: Japanese Registered Utility Model No. 2519149Patent Document 5: Japanese Unexamined Patent Application Publication No. 11-30261Patent Document 6: Japanese Unexamined Patent Application Publication No. 10-306836

However, when an opening (hole) which enables an accommodation portion to communicate with the atmosphere is not provided, with consideration of the leakage of the viscous fluid from the opening (hole), air is collected in the accommodation portion to make the assembly inconvenient, the air is mixed in the viscous liquid to make the damping torque non-uniform, and the precision of the torque becomes not constant (non-uniformity of the damping torque occurs).

In addition, in the rotary damper disclosed in Patent Document 6, although the air which is collected in the concave portion of the rotation body at a time when the rotation body is attached can be discharged through the air discharge path, when a capping member is attached after the attachment of the rotation body, air is trapped in the casing by the capping member.

When the air is trapped in the casing as described above, the damping torque becomes non-uniform, and the precision of the torque becomes not constant.

DISCLOSURE OF THE INVENTION

The present invention is contrived to solve the above-described problems and provides a rotary damper capable of being easily assembled by decreasing the remaining air in the accommodation portion and reducing the non-uniformity of damping torque (keeping the precision of the torque constant).

The present invention is as follows.

a driven rotation member that is integrally formed with a rotation portion engagable with a driving member;

a fixing and supporting member that holds the driven rotation member rotatably;

an accommodation portion that is defined between the fixing and supporting member and the driven rotation member, and

a viscous fluid that is stored in the accommodation portion and damps a relative rotation of the driven rotation member and the fixing and supporting member, wherein

a seal member that seals an outer circumference of the accommodation portion to allow the driven rotation member and the fixing and supporting member to relatively rotate is provided,

an opening that enables a portion located more inside than the seal member of the accommodation portion with atmosphere is provided in at least one of the driven rotation member and the fixing and supporting member, and

the opening is closed so as not to obstruct the relative rotation of the driven rotation member and the fixing and supporting member when or after the driven rotation member and the fixing and supporting member are assembled.

(2). The rotary damper described in (1), wherein a closing means for closing the opening is a welding of an opening located in the front end of the driven rotation member.

(3). The rotary damper described in (1) or (2), wherein a gap regulating portion for regulating a gap in a direction of a rotation shaft around which the driven rotation member and the fixing and supporting member relatively rotate when the driven rotation member and the fixing and supporting member are assembled is provided in one of the driven rotation member and the fixing and supporting member.

(4) The rotary damper described in (3), wherein

a center shaft is provided in a center of the fixing and supporting member,

a cylinder-shaped portion having the opening into which the center shaft is inserted is provided in the driven rotation member, and

a welding regulating portion for regulating contacting a melted portion of the cylinder-shaped portion to the center shaft is provided in the cylinder-shaped portion.

(5) The rotary damper described in (4), wherein the welding regulating portion additionally serves as the gap regulating portion.

(6) The rotary damper described in any one of (1) to (5), wherein

a center shaft is provided in the center of the fixing and supporting member,

a cylinder-shaped portion having the opening into which the center shaft is inserted is provided in the driven rotation member, and

a complementary engaging portion for regulating an displacement of the driven rotation member and the fixing and supporting member in a direction of a rotation shaft around which the driven rotation member and the fixing and supporting member relatively rotate and allowing the driven rotation member and the fixing and supporting member to relatively rotate is provided between an inner circumference of the cylinder-shaped portion and an outer circumference of the center shaft.

(7). The rotary damper described in any one of (1) to (5), wherein an engaging portion for regulating an displacement of the driven rotation member and the fixing and supporting member in a direction of a rotation shaft around which the driven rotation member and the fixing and supporting member relatively rotate and allowing the driven rotation member and the fixing and supporting member to relatively rotate is provided in an outer portion of the driven rotation member and the fixing and supporting member.

a driven rotation member integrally formed with a rotation portion engagable with a driving member;

a fixing and supporting member that holds the driven rotation member rotatably;

an accommodation portion that is defined between the fixing and supporting member and the driven rotation member, and

a viscous fluid that is stored in the accommodation portion and damps a relative rotation of the driven rotation member and the fixing and supporting member, wherein

a center shaft is provided in the center of the fixing and supporting member,

a hole into which the center shaft is rotatably inserted is provided in the driven rotation member,

a seal member that prevents a leakage of the viscous fluid from a portion between the driven rotation member and the fixing and supporting member is provided,

a first path through which the accommodation portion communicates with an outside is provided between the center shaft and a surrounding face forming the hole, and

a second path that allows a bottom side of the seal member inside the accommodation portion to communicate with the first path is provided in the driven rotation member.

a driven rotation member integrally formed with a rotation portion engagable with a driving member;

a fixing and supporting member that holds the driven rotation member rotatably;

an accommodation portion that is defined between the fixing and supporting member and the driven rotation member, and

a viscous fluid that is stored in the accommodation portion and damps a relative rotation of the driven rotation member and the fixing and supporting member, wherein

a center shaft is provided in a center of the fixing and supporting member,

a hole into which the center shaft is rotatably inserted is provided in the driven rotation member,

a seal member that prevents a leakage of the viscous fluid from a portion between the driven rotation member and the fixing and supporting member is provided,

a first path through which the accommodation portion communicates with an outside is provided between the driven rotation member and the fixing and supporting member, and

a constriction portion is provided in the first path.

(10) The rotary damper described in (9), wherein a plurality of the constriction portions are provided in the first path in a direction that the viscous fluid flows.

(11). The rotary damper described in (9) or (10), wherein an upper wall face forming the first path is an upward inclining face.

a driven rotation member integrally formed with a rotation portion engagable with a driving member;

a fixing and supporting member that holds the driven rotation member rotatably;

an accommodation portion that is defined between the fixing and supporting member and the driven rotation member, and

a viscous fluid that is stored in the accommodation portion and damps the relative rotation of the driven rotation member and the fixing and supporting member, wherein

a center shaft is provided in a center of the fixing and supporting member,

a hole into which the center shaft is rotatably inserted is provided in the driven rotation member,

a seal member which prevents a leakage of the viscous fluid from a portion between the driven rotation member and the fixing and supporting member is provided, and

a first path that allows an outside of the accommodation portion and a bottom side of the seal member inside the accommodation portion to communicate with each other is provided in the center shaft.

(13). The rotary damper described in any one of (8) to (12), wherein the first path is closed after the driven rotation member and the fixing and supporting member are assembled.

a first member;

a second member that holds the first member rotatably;

an accommodation portion that is defined between the first member and the second member;

a viscous fluid that is stored in the accommodation portion and damps a rotation of the first member with respect to the second member;

a seal member that seals the accommodation portion from atmosphere in a state where the first member is rotatable with respect to the second member; and

a close portion that is provided in at least one of the first member and the second member, and is formed by closing an aperture, which communicates the accommodation portion with atmosphere during assembly processing of the first member and the second member.

(15). The rotary damper according to (14), wherein the aperture is provided at a front end of the first member.

(16). The rotary damper according to (15), wherein the close portion is formed by welding the aperture provided at a front end of the first member.

(17). The rotary damper according to (15), wherein the close portion is formed by assembling the first member and the second member.

(18). The rotary damper according to (14), wherein the aperture is provided at a bottom of the second member.

(19) The rotary damper according to (18), wherein the close portion is formed by welding the aperture provided at a bottom of the second member.

(20). The rotary damper according to any one of (14) to (19), wherein at least one of the first member and the second member includes a gap regulating portion for regulating a gap in a direction of a rotation shaft around which the first member rotates with respect to the second member when the first member and the second member are assembled.

(21). The rotary damper according to any one of (14) to (16), wherein

the second member includes a center shaft,

the first member includes a cylinder-shaped portion having a hollow portion into which the center shaft is inserted, and having a welding regulating portion for regulating contacting a melted portion of the cylinder-shaped portion to the center shaft.

(22). The rotary damper according to (21), wherein the welding regulating portion additionally serves as the gap regulating portion.

(23). The rotary damper according to any one of (14) to (21), wherein

the second member includes a center shaft,

the first member includes a cylinder-shaped portion having a hollow portion into which the center shaft is inserted, and wherein

a complementary engaging portion for regulating an displacement of the first member and the second member in a direction of a rotation shaft around which the first member rotates with respect to the second member and allowing the first member to rotate with respect to the second member is provided between an inner circumference of the cylinder-shaped portion and an outer circumference of the center shaft.

(24). The rotary damper according to any one of (14) to (21), wherein

at least one of the first member and the second member includes a claw portion for regulating an displacement of the first member and the second member in a direction of a rotation shaft around which the first member rotates with respect to the second member and allowing the first member to rotate with respect to the second member.

(25). The rotary damper according to any one of (14) to (24), wherein

the second member includes a center shaft,

the first member includes a cylinder-shaped portion having a hollow portion into which the center shaft is inserted, and wherein

a first path through which the accommodation portion communicates with the close portion is provided between the center shaft and the cylinder-shaped portion.

(26). The rotary damper according to (25), wherein the first member includes a second path that allows a bottom side of the seal member inside the accommodation portion to communicate with the first path.

(27). The rotary damper according to any one of (14) to (24), wherein a third path through which the accommodation portion communicates with the close portion is provided between the first member and the second member, and

a constriction portion is provided in the third path.

(28). The rotary damper according to (27), wherein a plurality of the constriction portions are provided in the third path in a direction that the viscous fluid flows.

(29). The rotary damper according to (27) or (28), wherein an upper wall face forming the third path is an upward inclining face.

(30). The rotary damper according to any one of (14) to (24), wherein

the second member includes a center shaft,

the first member includes a cylinder-shaped portion having a hollow portion into which the center shaft is inserted, and wherein

a fourth path that allows a bottom side of the seal member inside the accommodation portion and close portion to communicate with each other is provided in the center shaft.

According to (1) of the invention, since an opening which enables a portion located more inside than the seal member of the accommodation portion to communicate with the atmosphere is provided in at least one of the driven rotation member and the fixing and supporting member and the opening is closed not to obstruct the relative rotation of the driven rotation member and the fixing and supporting member when or after the driven rotation member and the fixing and supporting member are assembled, the air remaining inside the accommodation portion is decreased to make the assembly easy, the air mixed in the viscous fluid is decreased to maintain the precision of the torque constant, and the closing operation of the opening is not required additionally to improve the efficiency of the assembly.

According to (2) of the invention, since a closing means for closing the opening is welding of an opening located in the front end of the driven rotation member, the opening can be closed assuredly to prevent the leakage of the viscous fluid from the opening.

According to (3) of the invention, a gap regulating portion for regulating a gap in a direction of a rotation shaft around which the driven rotation member and the fixing and supporting member relatively rotate is provided in one of the driven rotation member and the fixing and supporting member when the driven rotation member and the fixing and supporting member are assembled, the gap between the driven rotation member and the fixing and supporting member is not changed to be able to maintain the precision of the torque constant.

According to (4) of the invention, since a center shaft is provided in a center of the fixing and supporting member, a cylinder-shaped portion having the opening into which the center shaft is inserted is provided in the driven rotation member, and a welding regulating portion for regulating contacting of the melted cylinder-shaped portion to the center shaft is provided in the cylinder-shaped portion, the attachment of the melt cylinder-shaped portion to the center shaft can be prevented to be able to assuredly rotate the driven rotation member and the fixing and the supporting member.

According to (5) of the invention, since the welding regulating portion additionally serves as the gap regulating portion, one component can have two functions, and accordingly, the configuration can be made simple compared with its function.

According to (6) of the invention, since a complementary engaging portion for regulating the displacement of the driven rotation member and the fixing and supporting member in a direction of a rotation shaft around which the driven rotation member and the fixing and supporting member relatively rotate and allowing the driven rotation member and the fixing and supporting member to relatively rotate is provided between an inner circumference of the cylinder-shaped portion and an outer circumference of the center shaft, it becomes difficult for the driven rotation member to be released from the fixing and supporting member, the driven rotation member and the fixing and supporting member can be formed using two face separation molding although a slider is used, and since the contacting portion between the driven rotation member and the fixing and supporting member contacts a center portion which has a small contacting area, a frictional resistance between the driven rotation member and the fixing and supporting member is reduced, and the frictional resistance between the driven rotation member and the fixing and supporting member is reduced further by interposing the viscous liquid between the driven rotation member and the fixing and supporting member.

According to (7) of the invention, since an engaging portion for regulating the displacement of the driven rotation member and the fixing and supporting member in a direction of a rotation shaft around which the driven rotation member and the fixing and supporting member relatively rotate and allowing the driven rotation member and the fixing and supporting member to relatively rotate is provided in an outer portion of the driven rotation member and the fixing and supporting member, the driven rotation member and the fixing and supporting member can be molded using two face separation molding although a slider is used.

According to (8) of the invention, since a first path through which the accommodation portion communicates with its outside is provided between the center shaft and a surrounding face forming the hole and a second path which allows a bottom of the seal member inside the accommodation portion to communicate with the first path is provided in the driven rotation member, the air located in the bottom side of the seal member inside the accommodation portion in which the atmosphere can be easily collected can be discharged outside of the accommodation portion through the second path and the first path.

Accordingly, the remaining air inside the accommodation portion is decreased to reduce the non-uniformity of the damping torque.

According to (9) of the invention, since a first path through which the accommodation portion communicates with its outside is provided between the driven rotation member and the fixing and supporting member and a constriction portion is provided in the first path, the speed of the viscous liquid moving through the first path is reduced by the constriction portion, and the moving speed of the air becomes relatively fast with respect to that of the viscous fluid, and accordingly, it becomes easy to discharge the atmosphere outside the accommodation portion.

Thus, the amount of the remaining air in the accommodation portion is decreased, thereby reducing the non-uniformity of the damping torque.

According to (10) of the invention, since a plurality of the constriction portions are provided in the first path in a direction that the viscous fluid flows, the speed of the viscous liquid moving through the first path is reduced further by the plurality of constriction portions, and accordingly, the air can be more easily discharged outside the accommodation portion by further increasing the relative moving speed of the atmosphere with respect to that of the viscous fluid.

Accordingly, the non-uniformity of the damping torque can be reduced more by further decreasing the remaining air inside the accommodation portion.

According to (11) of the invention, since an upper wall side forming the first path is an upward inclining side, the air is lifted along the top face, and accordingly, it becomes much easier to discharge the air outside the accommodation portion.

Accordingly, the non-uniformity of damping torque can be reduced much more by even further decreasing the remaining air inside the accommodation portion.

According to (12) of the invention, since a first path which allows the outside of the accommodation portion and the bottom side of the seal member inside the accommodation portion to communicate with each other is provided in the center shaft, the air located in the bottom side of the seal member inside the accommodation portion in which the atmosphere can be easily collected can be discharged outside of the accommodation portion through the first path.

Accordingly, the non-uniformity of damping torque can be reduced by decreasing the remaining air inside the accommodation portion.

According to (13) of the invention, since the first path is closed after it is assembled, an outlet of the viscous liquid is removed, and accordingly, the leakage of the viscous liquid outside the accommodation portion can be prevented.

According to (14) of the invention, an aperture, which communicates the accommodation portion with atmosphere during assembly processing of the first member and the second member, is provided in at least one of the first member (driven rotation member) and the second member (fixing and supporting member) and the aperture is closed thereby forming the close portion. Thus the air remaining inside the accommodation portion is decreased to make the assembly easy, the air mixed in the viscous fluid is decreased to maintain the precision of the torque constant.

According to (15) to (19) of the invention, the air remaining inside the accommodation portion is decreased to make the assembly easy, the air mixed in the viscous fluid is decreased to maintain the precision of the torque constant.

According to (20) of the invention, the gap between the first member and the second member is not changed to be able to maintain the precision of the torque constant.

According to (21) of the invention, the attachment of the melt cylinder-shaped portion to the center shaft can be prevented to be able to assuredly rotate the first member with respect to the second member.

According to (22) of the invention, one component can have two functions, and accordingly, the configuration can be made simple compared with its function.

According to (23) of the invention, it becomes difficult for the first member to be released from the second member, the first member and the second member can be formed using two face separation molding although a slider is used, and since the contacting portion between the first member and the second member contacts a center portion which has a small contacting area, a frictional resistance between the first member and the second member is reduced, and the frictional resistance between the first member and the second member is reduced further by interposing the viscous liquid between the first member and the second member.

According to (24) of the invention, the first member and the second member can be molded using two face separation molding although a slider is used.

According to (25) and (26) of the invention, since a first path through which the accommodation portion communicates with the close portion is provided between the center shaft and the cylinder-shaped portion and a second path that allows a bottom side of the seal member inside the accommodation portion to communicate with the first path is provided in the first member, the air located in the bottom side of the seal member inside the accommodation portion in which the atmosphere can be easily collected can be discharged outside of the accommodation portion through the second path and the first path.

Accordingly, the remaining air inside the accommodation portion is decreased to reduce the non-uniformity of the damping torque.

According to (27) of the invention, since a first path through which the accommodation portion communicates with its outside is provided between the first member and the second member and a constriction portion is provided in the third path, the speed of the viscous liquid moving through the third path is reduced by the constriction portion, and the moving speed of the air becomes relatively fast with respect to that of the viscous fluid, and accordingly, it becomes easy to discharge the atmosphere outside the accommodation portion.

Thus, the amount of the remaining air in the accommodation portion is decreased, thereby reducing the non-uniformity of the damping torque.

According to (28) of the invention, since a plurality of the constriction portions are provided in the third path in a direction that the viscous fluid flows, the speed of the viscous liquid moving through the third path is reduced further by the plurality of constriction portions, and accordingly, the air can be more easily discharged outside the accommodation portion by further increasing the relative moving speed of the atmosphere with respect to that of the viscous fluid.

Accordingly, the non-uniformity of the damping torque can be reduced more by further decreasing the remaining air inside the accommodation portion.

According to (29) of the invention, since an upper wall side forming the third path is an upward inclining side, the air is lifted along the top face, and accordingly, it becomes much easier to discharge the air outside the accommodation portion.

Accordingly, the non-uniformity of damping torque can be reduced much more by even further decreasing the remaining air inside the accommodation portion.

According to (30) of the invention, since a fourth path that allows a bottom side of the seal member inside the accommodation portion and close portion to communicate with each other is provided in the center shaft, the air located in the bottom side of the seal member inside the accommodation portion in which the atmosphere can be easily collected can be discharged outside of the accommodation portion through the first path.

Accordingly, the non-uniformity of damping torque can be reduced by decreasing the remaining air inside the accommodation portion.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1is an exploded front sectional view of a rotary damper according to a first embodiment of the present invention.FIG. 2is a plan view of a driven rotation member shown inFIG. 1.FIG. 3is a plan view of a fixing and supporting member shown inFIG. 1.FIG. 4is a front sectional view of a rotary damper during a fabrication process of attaching components shown inFIG. 1.FIG. 5is a plan view of a rotary damper during a fabrication process of attaching the components shown inFIG. 1.FIG. 6is a front sectional view of the rotary damper which is fabricated by attaching the components shown inFIG. 1and is attached to an attachment target member.

InFIG. 1, a reference sign D denotes the rotary damper. The rotary damper includes a driven rotation member (first member)11made of a synthetic resin, a fixing and supporting member (second member)21made of the synthetic resin and called a housing which supports the driven rotation member11to be freely rotatable, an O ring31which is attached to the driven rotation member11and suitably formed of a silicon rubber, EPDM (ethylene propylene diene rubber), or the like as a sealing member sealing an outer circumference end of a circular accommodation portion41(seeFIG. 4or6) which is defined between the driven rotation member11and the fixing and supporting member21while allowing relative rotation of the driven rotation member11and the fixing and supporting member21, and a viscous fluid51(seeFIG. 4orFIG. 6) such as grease, silicon oil, or the like which is stored in the accommodation portion41(seeFIG. 4orFIG. 6) defined between the driven rotation member11and the fixing and supporting member21and damps the relative rotation of the driven rotation member11and the fixing and supporting member21.

The driven rotation member11includes a gear portion12(also seeFIG. 2) as a rotation portion which is engaged with a driving member such as a gear or a rack, a holding flange portion13which is provided under the gear portion12as one structure, an outer cylinder wall14which has the center of the gear portion12as its center and is provided under the holding flange portion13as one structure, and a holding flange portion15which is formed in a lower end of an outer circumference of the outer cylinder wall14as one structure to face the holding flange portion13and holds the O ring31in the outer circumference of the outer cylinder wall14by using the holding flange portion13. Further an inner cylinder wall16which has the center of the gear portion12as a center, has an opening having a hallow portion communicating between the upper and lower sides in the inside of the outer cylinder wall14, and communicating with the accommodation portion41is provided in the driven rotation member11as one structure, and a front end (upper end) of inner cylinder wall16is opened so as to form an aperture.

A revolving stair portion16sis provided in an upper end of the outer circumference of the inner cylinder wall16.

In addition, in an inner circumference of the inner cylinder wall16, for example, six grooves17which is disposed at equal distances of 60 degrees and which vertically extend from a lower end of the inner circumference to about a center portion is provided. In addition, engaging protrusions18(seeFIG. 2) which are disposed in an upper side of the grooves17, and form a complementary engaging portion which can be relatively rotated with respect to a lock rotation groove26of the fixing and supporting member21to be described later are provided. In the engaging protrusions18, an upper end is formed to be planar and a lower side extends outward in a downward direction. As an example, the engaging protrusions are disposed at intervals of 180 degrees therebetween. A welding regulating portion19(See alsoFIG. 2) locates over upper sides of the engaging protrusions18as one structure, and serves as a gap regulation portion for regulating a gap in a rotation shaft around which the driven rotation member11and the fixing and supporting member21rotate relatively when the driven rotation member11and the fixing and supporting member21are assembled and additionally regulating contacting a close portion16c(seeFIG. 6) which is formed by solidification of an upper end portion of a melted inner cylinder wall16to a center shaft25of the fixing and supporting member21as described later when the upper end portion of the inner cylinder wall16is welded for closing the upper end portion of the melted inner cylinder wall16.

Chamfer processes are performed in a lower end of an outer circumference of the holding flange portion15and in a lower end of an inner circumference of the inner cylinder wall16.

The fixing and supporting member21is provided with a base wall22(seeFIG. 3) having a planar circular shape, an outer cylinder wall23(seeFIG. 3) provided in an outer edge of the base wall22as one structure, an inner cylinder wall24(seeFIG. 3) which is concentric with the case wall22and inserted into a circular groove formed by the outer cylinder wall14of the driven rotation member11and the inner cylinder wall16, a center shaft25(seeFIG. 3also) which is formed in the center of the base wall22as one body and is inserted into the inner cylinder wall16of the driven rotation member11, and an attachment portion27(seeFIG. 3) which is formed, for example, at intervals of 180 degrees, in one body.

A lower end portion23dwhich can accommodate the holding flange portion15of the driven rotation member11rotatably in its inside is formed in a lower end of the inner side of the outer cylinder wall23, and an upper stair portion23uwhich can accommodate the holding flange portion13of the driven rotation member11rotatably in its inside is formed in an upper end of the inner side of the outer cylinder wall23.

A chamfer process is performed on an upper end of an outer circumference of the center shaft25, and a lock rotation groove26having a flat upper end which forms a complementary regulating portion that can be rotated relatively with respect to the engaging protrusion18of the driven rotation member11is formed on the outer circumference at a height corresponding to the engaging protrusion18of the driven rotation member11.

The attachment portion27extends outward from the base portion22and then extends upward. The attachment portion27includes a holding piece28having a holding claw28aon an upper end of its outside and an a holding protrusion29(SeeFIG. 3) extending outward from the base portion22and having a gap of an attachment target member, for example, an attached plate E (seeFIG. 6), which is held between the holding protrusion29and the holding claw28a.

InFIG. 4, a reference sign H denotes a heat tip as a welding jig. A concave portion c which forms a part of a sphere accepting an upper side of the inner cylinder wall16of the driven rotation member11is formed in the lower end of the hit tip, and a protrusion p is formed in the center of the concave portion c.

Next, an example of assembly of the rotary damper D will be described.

At first, as shown inFIG. 1, a fixing and supporting member21is put on a workbench and a predetermined amount of a viscous fluid51is injected into a circular concave portion formed by an outer cylinder wall23and an inner cylinder wall24.

The lower side of the driven rotation member11in which the O ring31is held in an outside of the outer cylinder wall14by the holding flange portions13and15is inserted into the fixing and supporting member21using the insertion of the center shaft25into the inner cylinder wall16as a guide.

As described above, when the bottom of the driven rotation member11is inserted into the fixing and supporting member21, the viscous fluid51and air are compressed by the driven rotation member11and the fixing and supporting member21to move a space between the driven rotation member11and the fixing and supporting member21from outside to inside. Then, the viscous fluid and air go into a space between the inner cylinder wall16and the center shaft25passing through the groove17.

Since the air moves faster than the viscous fluid51, air does not remain in the accommodation portion41which is formed by the driven rotation member11and the fixing and supporting member21.

As described above, when the bottom of the driven rotation member11is inserted into the fixing and supporting member21, the holding flange portion15, as shown inFIG. 4, is inserted rotatably into the inside of the outer cylinder wall23, and the O ring31seals between the outer cylinder wall23and the outer cylinder wall14while allowing the driven rotation member11and the fixing and supporting member21to be relatively rotatable.

The center shaft25, as shown inFIG. 4, is placed inside the inner cylinder wall16, and when the center shaft25goes through the engaging protrusion18to collide with the welding regulating portion19, the engaging protrusion18is inserted into the lock rotation groove26, and the engaging protrusion18, as shown inFIG. 4, is engaged with the lock rotation groove26.

As shown inFIG. 4, the heat tip H is heated by flowing a current in a status that the driven rotation member11is assembled to the fixing and supporting member21, an upper end (aperture) of the inner cylinder wall16is welded to be closed by placing the upper end portion of the inner cylinder wall16in the concave portion c of the heat tip H as indicated by the alternate long and two short dashes line and pressing the heat tip down, and then, the heat tip is cooled and removed, and thereby the rotary damper D in a status shown inFIG. 6is acquired. Then, the assembly is completed.

Next, an example of the attachment of the rotary damper D will be described.

As shown inFIG. 6, the rotary damper D is attached to the attached plate E by pinching the attachment plate E between the holding claw28aand the holding protrusion29using a hole which is provided in the attachment plate E, that is a hole having the same circular shape as the bottom wall22of the fixing and supporting member21and having a notch into which the attachment portion27can be inserted at opposing positions of an outer circumference at 180 degrees.

Next, the operation of the rotary damper will be described.

At first, when the driven rotation member11is rotated by the rotation of the gear portion12which is interlocked with a gear, a rack, or the like, the rotation of the driven rotation member11is damped by a viscous resistance and a shearing resistance of the viscous fluid51interposed between the driven rotation member11and the fixing and supporting member21.

Accordingly, the gear portion12of the driven rotation member11damps the rotation or movement of the gear, the rack, or the like which is interlocked with the driven rotation member, so that the gear, the rack, or the like is slowly rotated or moved.

As described above, according to a first embodiment of the present invention, since the inner cylinder wall16(opening) which enables a center portion of the accommodation portion41to communicate with the atmosphere is provided in the driven rotation member11and the inner cylinder wall16(opening) is closed not to obstruct the relative rotation of the driven rotation member11and the fixing and supporting member21after the driven rotation member11and the fixing and supporting member21are assembled, the remaining air in the accommodation portion41is decreased. Accordingly, it becomes easy to assemble the driven rotation member11and the fixing and supporting member21, and the precision of the torque can be maintained constantly by decreasing the amount of the air that is mixed in the viscous fluid51.

In addition, since the closing means which closes the inner cylinder wall16(opening) is welding of the upper end (front end opening portion, closing member) of the inner cylinder wall16, the inner cylinder wall16(opening) can be closed assuredly without preparing an additional closing member, and accordingly, the leakage of the viscous fluid51from the inner cylinder wall16(opening) can be prevented.

When the driven rotation member11and the fixing and supporting member21are assembled, since the gap regulating portion (welding regulating portion19) which regulates a gap between the driven rotation member11and the fixing and supporting member in a direction of the rotation shaft around which the driven rotation member11and the fixing and supporting member21relatively rotates is provided to the driven rotation member11, the gap between the driven rotation member11and the fixing and supporting member21is not changed, and accordingly the precision of the torque can be maintained constantly.

Since the center shaft25is provided in a center of the fixing and supporting member21, the inner cylinder wall16(cylinder-shaped portion) having the opening into which the center shaft25is inserted is provided in the driven rotation member11, and the welding regulating portion19which regulates the contacting of an upper end portion of the welded inner cylinder wall16to the center shaft25is provided in the inner cylinder wall16, the attachment of the upper end of the welded inner cylinder wall16to the center shaft25can be prevented, and accordingly, the driven rotation member11and the fixing and supporting member21can be assuredly rotated.

In addition, since the welding regulating portion19serves as a gap regulating portion additionally, two functions can be implemented in one component, and accordingly, the structure can be made simple compared with its functions.

The complimentary engaging portion (engaging portion18and engaging rotation groove26) which regulates the movement in a direction of a shaft around which the driven rotation member11and the fixing and supporting member21relatively rotate and serves as an engaging portion which allows the driven rotation member11and the fixing and supporting member21to relatively rotate is provided between an inner circumference of the inner cylinder wall16and an outer circumference of the center shaft25, it becomes difficult for the driven rotation member11to be released from the fixing and supporting member21, and the driven rotation member11and the fixing and supporting member21can be formed using two face separation molding although a slider is used. In addition, since the contacting portion between the driven rotation member11and the fixing and supporting member21contacts a center portion which has a small contacting area, a frictional resistance between the driven rotation member11and the fixing and supporting member21is reduced, and the frictional resistance between the driven rotation member11and the fixing and supporting member21is reduced further by interposing the viscous liquid51between the driven rotation member11and the fixing and supporting member21.

In addition, since the holding flange portion15is provided in the outer cylinder wall14, the O ring31is not released from the outer cylinder wall14, and accordingly, the assembly operation can be performed efficiently.

In addition, since the groove17is provided in the inner circumference of the inner cylinder wall16, the air inside the accommodation portion41is discharged along the groove17from the inner cylinder wall16and the viscous liquid51is inserted between the inner cylinder wall16and the inner cylinder wall24along the groove17, the remaining air inside the accommodation portion41further decreases, and accordingly, the assembly becomes more easy, and the air mixed in the viscous liquid51further reduces, and accordingly, the precision of the torque can be maintained more constantly.

FIG. 7is a front sectional view of a rotary damper according to a second embodiment of the present invention. A same symbol is attached to a same or corresponding portion inFIG. 7as/to a portion inFIGS. 1 to 6, and the description of the portion is omitted.

A reference numeral13A denotes a holding flange portion inFIG. 7, and a predetermined gap is formed between the holding flange portion and a gear portion12, so that an engaging claw23iof an outer cylinder wall23A to be described later can go through the gap.

A reference numeral23A denotes an outer cylinder wall which is formed in an outer frame of a bottom wall22as one structure. On the inner side of the outer cylinder wall23A, engaging claws23iwhich are protruded inward with the upper sides lowered inward and are engaged with the top face of the holding flange portion13A of the driven rotation member11rotatably are provided in a circumferential direction at intervals of a predetermined distance therebetween, for example, 90 degree intervals.

The holding flange portion13A and the engaging claw23iconstruct an engaging portion in which a driving member11and a fixing and supporting member21are relatively rotatable.

Other portions of the rotary damper D according to the second embodiment of the invention have the same configurations as in the first embodiment.

Next, an example of assembly of the rotary damper D will be described.

At first, as shown inFIG. 1, a fixing and supporting member21is put on a workbench and a predetermined amount of a viscous fluid51is injected into a circular concave portion formed by an outer cylinder wall23A and an inner cylinder wall24.

The bottom of the driven rotation member11in which the O ring31is held in an outside of the outer cylinder wall14by the holding flange portions13A and15is inserted into the fixing and supporting member21using the insertion of the center shaft25into the inner cylinder wall16as a guide.

As described above, when the bottom of the driven rotation member11is inserted into the fixing and supporting member21, the viscous fluid51and air are compressed by the driven rotation member11and the fixing and supporting member21to move a space between the driven rotation member11and the fixing and supporting member21from outside to inside. Then, the viscous fluid and air go into a space between the inner cylinder wall16and the center shaft25through the groove17.

Since the air moves faster than the viscous fluid51, air does not remain in the accommodation portion41which is formed by the driven rotation member11and the fixing and supporting member21.

As described above, when the bottom of the driven rotation member11is inserted into the fixing and supporting member21, the holding flange portion15, as shown inFIG. 7, is inserted into the inside of the outer cylinder wall23A rotatably, and the O ring31seals between the outer cylinder wall23A and the outer cylinder wall14while allowing the driven rotation member11and the fixing and supporting member21to be relatively rotatable. The engaging claw23iis expanded to be open and is shrunk to be closed after passing by a holding flange portion13A, so that the engaging claw23iis engaged with the top face of the holding flange portion13A to be rotatable.

The center shaft25, as shown inFIG. 7, is inserted into the inner cylinder wall16. When the center shaft25goes through the engaging protrusion18to collide with the welding regulating portion19, the engaging protrusion18enters into the lock rotation groove26, and the engaging protrusion18is engaged with the lock rotation groove26.

As shown inFIG. 4, the heat tip H is heated by flowing a current in a status that the driven rotation member11is assembled to the fixing and supporting member21, an upper end (aperture) of the inner cylinder wall16is welded to be closed by placing the upper end portion of the inner cylinder wall16in the concave portion c of the heat tip H as indicated by the alternate long and two short dashes line and pressing the heat tip down, and then, the heat tip is cooled and removed, and thereby the rotary damper D in a status shown inFIG. 7is acquired. Then, the assembly is completed.

The attachment and operation of the rotary damper D in the second embodiment is the same as in the first embodiment, and thus the description thereof will be omitted.

The same advantages as in the first embodiment can be acquired in the second embodiment.

Since an engaging portion (a holding flange portion13A and an engaging claw23i) in which the driven rotation member11and the fixing and supporting member21can relatively rotate is provided an outer portion of the driven rotation member11and the fixing and supporting member21, the driven rotation member11and the fixing and supporting member21can be formed using two face separation molding although a slider is used.

FIG. 8is a front sectional view of a rotary damper according to a third embodiment of the present invention. A same symbol is attached to a same or corresponding portion inFIG. 8as/to a portion inFIGS. 1 to 7, and the description of the portion is omitted.

InFIG. 8, a reference numeral13B denotes a holding flange portion which is provided at the bottom side of a gear portion12as one structure. In the outer frame of the holding flange portion, four engaging claws13cwhich extends outward and then, downward forming an “L” shape, the lower end on the inner side is an inclination which increases its opening width from the upper side to the lower side, and is engaged with a rotation lock portion23oof the outer cylinder wall23B to be described later are provided at predetermined intervals, for example, 90 degrees intervals in a circumference direction.

A reference numeral23B denotes an outer cylinder wall formed in an outer frame of the bottom wall22as one structure. In the upper end on the outside of the outer cylinder wall, rotation lock portions23oformed as an inclination in which the upper side is lowered in an outward direction to be protruded on the outer side and is engaged with the bottom face of the engaging claws13cof the holding flange portion13B of the driven rotation member11rotatably.

The engaging claw13cand the rotation lock portion23oconstruct an engaging portion in which the driven rotation member11and the fixing and supporting member21can relatively rotate.

Other portions of the rotary damper D according to the third embodiment of the invention have the same configurations as in the first embodiment.

The assembly of the rotary damper D in the third embodiment can be performed in the same manner as the second embodiment, and the attachment and operation of the rotary damper D in the third embodiment is the same as in the first embodiment, and thus the description thereof will be omitted.

The same advantages as in the second embodiment can be acquired in the third embodiment.

FIG. 9is an exploded front sectional view of rotary damper according to a fourth embodiment of the present invention, andFIG. 10is a front sectional view of a rotary damper which is fabricated by assembling components shown inFIG. 9. A same symbol is attached to a same or corresponding portion inFIG. 9as/to a portion inFIGS. 1 to 8, and the description of the portion is omitted.

InFIG. 9, a reference numeral16X denotes an inner bottomed cylinder wall which is opened downward, and a groove17and an engaging protrusion18are provided inside the bottomed cylinder wall16X.

A reference numeral25A denotes a center shaft, and a through hole25tis provided in the center of the center shaft25A.

The height (length) of the center shaft25A is configured such that the bottom of the inner bottomed cylinder wall16X contacts an upper end face of the center shaft25A to close the through hole25twhen the driven rotation member11is assembled to the fixing and supporting member21.

Accordingly, the front end opening portion and the bottomed cylinder wall16X as a closing member can be configured to serve as a gap regulating portion additionally.

The assembly of the rotary damper D in the fourth embodiment can be performed the same as in the first embodiment (the welding process using the heat tip H is excluded) as shown inFIG. 10.

The attachment and operation of the rotary damper D in the fourth embodiment is the same as in the first embodiment, and thus the description thereof will be omitted.

The same advantages as in the first embodiment can be acquired in the fourth embodiment.

Since a configuration in which the through hole25t(opening) is closed when the driven rotation member11and the fixing and supporting member21are assembled is used, an operation for closing the through hole25t(opening) is not required additionally, and the assembly can be performed efficiently.

In addition, since the inner bottomed cylinder wall16X serves as a closing member additionally, two functions can be implemented in one component, and accordingly, the structure can be made simple compared with its functions.

FIG. 11is a front sectional view of a rotary damper according to a fifth embodiment of the present invention. A same symbol is attached to a same or corresponding portion inFIG. 11as/to a portion inFIGS. 1 to 10, and the description of the portion is omitted.

A difference of the fifth embodiment from the fourth embodiment is in that the bottom of the inner bottomed cylinder wall16X is spaced apart from the upper end face of the center shaft25A in the sate where the driven rotation member11is assembled to the fixing and supporting member21and that an opening end (lower end) of the through hole25t(opening) is closed by welding after the assembly of the driven rotation member11and the fixing and supporting member21thereby forming a close portion.

The same advantages as in the first embodiment can be acquired in the fifth embodiment.

FIG. 12is an exploded front sectional view of a rotary damper according to a sixth embodiment of the invention.FIG. 13(a) is a plan view of a driven rotation member shown inFIG. 12.FIG. 13(b) is a bottom view of the driven rotation member shown inFIG. 12.FIG. 13(c) is a sectional view taken along the line A-A shown inFIG. 12.FIG. 14is a plan view of a fixing and supporting member shown inFIG. 12.FIG. 15is a front sectional view of a rotary damper during a fabrication process by assembling components shown inFIG. 12.FIG. 16is a plan view of a rotary damper during a fabrication process by assembling the components shown inFIG. 12.FIG. 17is a front sectional view of a rotary damper which is fabricated by assembling the components shown inFIG. 12and is attached to an attachment target member.

InFIG. 12, a reference sign D denotes a rotary damper. The rotary damper includes a driven rotation member61(first member) made of a synthetic resin, a fixing and supporting member (second member)71called housing made of a synthetic resin which supports the driven rotation member61to be freely rotatable, an O ring81which is attached to the driven rotation member and suitably formed of a silicon rubber, EPDM (ethylene propylene diene rubber), or the like as a sealing member sealing an outer circumference end of a circular accommodation portion91(seeFIG. 4or6) which is defined between the driven rotation member61and the fixing and supporting member71to allow relative rotation of the driven rotation member61and the fixing and supporting member71, and a viscous fluid101(seeFIG. 15orFIG. 17) such as grease, silicon oil, or the like which is stored in the accommodation portion91(seeFIG. 15orFIG. 17) defined by the driven rotation member and the fixing and supporting member71and damps relative rotation of the driven rotation member61and the fixing and supporting member71.

The driven rotation member61includes a gear portion62(seeFIGS. 13(a) and13(b)) as a rotation portion which is engaged with a driving member such as a gear or a rack, an inner cylinder wall (shaft portion)63(seeFIGS. 13(a) to13(c)) provided in the gear portion to penetrate the gear portion62with having the center of the gear portion62as a center, and a rotor portion66(seeFIGS. 13(b) and13(c)) which is provided in an lower end of the outer circumference of the inner cylinder wall63to face the gear portion62, holds the O ring81to the gear portion62in the inner cylinder wall63, and is inserted into an accommodation portion91in the shape of a circle, when viewed in a plane, concentric with the gear portion62(seeFIG. 15orFIG. 17).

A stair portion63a(seeFIG. 13(a)) which is formed thin and revolves outward is provided in the upper end portion of the inner cylinder wall63.

In addition, in an inner circumference of the inner cylinder wall63, for example, four grooves63b(seeFIGS. 13band13(c) also) having equal intervals of 90 degrees and extending from a lower end of the inner circumference wall to an approximately vertically center portion are formed. In addition, engaging protrusions64(seeFIGS. 13(a) and13(b) also) which are disposed in an upper side of the grooves63b, and form a complementary engaging portion which can be rotated relatively with respect to a lock rotation groove73aof the fixing and supporting member71are formed. In the engaging protrusions64, an upper end is flat and a lower side is inclined to extend outward in a downward direction. As an example, the engaging protrusions64are disposed at intervals of 180 degrees therebetween. A welding regulating portion65(See alsoFIGS. 13(a) and13(b)) locates over the upper sides of the engaging protrusions64and serves as a gap regulation portion for regulating a gap in a rotation shaft around which the driven rotation member61and the fixing and supporting member71rotate relatively when the driven rotation member61and the fixing and supporting member71are assembled and additionally regulating contacting a close portion63d(seeFIG. 17)which is formed by solidification of an upper end portion of a melted inner cylinder wall63to the center shaft73of the fixing and supporting member71when the upper end portion of the inner cylinder wall63is welded for closing the upper end portion of the melted inner cylinder wall63.

Holes63c(second path) (seeFIG. 13(c)), for example, extending from an upper end portion of the rotor portion66in a radial direction are provided in the inner cylinder wall63at 180 degree intervals.

The rotor portion66includes a flange portion67(seeFIGS. 13(b) and13(c)) in the shape of a circle when viewed in a plane and a protrusion inclination portion68(seeFIG. 13(b)) protruding in the shape of an I-cut under the flange portion67.

The bottom68a(upper wall side) of the protrusion inclination portion68is an inclination face (seeFIG. 13(b)) increasing its height toward the center (inner cylinder wall63).

The fixing and supporting member71includes a bottom wall72(seeFIG. 14) in the shape of a circle when viewed in a plane, the bottom face in the inner side of which moves up toward its center, a center shaft73(seeFIG. 14) which is provided in the center of the bottom wall72on the inner side and is inserted into an inner cylinder wall63(hole) of the driven rotation member61, an outer cylinder wall74(seeFIG. 14) which is provided in an outer circumference of the bottom wall72, and an attachment portion75(seeFIG. 14) provided, for example, at 180 degree intervals in the outer circumference of the outer cylinder wall74.

A plurality of, for example, three (steps), concentric stair portions72ahaving the center shaft73as its center are provided on the inner side of the bottom wall72.

A chamfer process is performed on an upper end of the outer circumference of the center shaft73. An engaging rotation groove73aforming a complimentary engaging portion which can be rotated relatively with respect to the engaging protrusion64of the driven rotation member61and having a flat upper end is provided in the outer circumference of the center shaft corresponding to the height of the engaging protrusion64of the driven rotation member61.

The attachment portion75includes a holding piece76(SeeFIG. 14) which extends outward from the outer cylinder wall74and then, extents upward and has a holding claw76aon its upper end on the outer side and a holding protrusion77(seeFIG. 14) extending outward from the outer cylinder wall74and having a gap of an attachment target member, for example, an attaching target plate E (seeFIG. 17), which is held between the holding protrusion77and the holding claw76a.

A viscous fluid101fills up the inside of the accommodation portion91which is defined by the driven rotation member61, the fixing and supporting member71, and an O ring81(seeFIG. 15or17).

A hole through which the center shaft73of the fixing and supporting member71rotatably passes through is formed by the inner cylinder wall63.

A first path70which enables the accommodation portion91which is filled up by the viscous fluid101to communicate with the outside of the fixing and supporting member71is formed by an inner side face of a bottom wall72constructing the fixing and supporting member71and an outer circumference face of the center shaft73, and an inner circumference of the inner cylinder wall63constructing the driven rotation member61and the bottom face68aof the protrusion inclination portion68(seeFIG. 15or17).

The constriction portion70a(seeFIG. 15or17) of the first path70is formed by an edge (corner portion) protruding outward above a stair portion72aprovided in the lower wall72and a bottom face68aof the protrusion inclination portion68.

InFIG. 15, a reference sign H denotes a heat tip as a welding jig. A concave portion c which forms a part of a sphere accepting an upper side of the inner cylinder wall63of the driven rotation member61is formed in the lower end of the hit tip, and a protrusion which is protruded downward is formed in the center of the concave portion c.

Next, an example of assembly of the rotary damper D will be described.

At first, as shown inFIG. 12, a fixing and supporting member71is put on a workbench and predetermined amount of a viscous fluid101is injected into a concave portion defined by a bottom wall72and an outer cylinder wall74.

The bottom of the driven rotation member61in which the O ring81is held in an outside of the inner cylinder wall63by the gear portion62and the rotor portion66is inserted into the fixing and supporting member71using the insertion of the center shaft73into the inner cylinder wall63as a guide.

As described above, when the bottom of the driven rotation member61, that is, a portion positioned lower than the gear portion62is inserted into the fixing and supporting member71, the viscous fluid101and air pass through the first path70between the bottom wall72and the rotor portion66to go into a space between the center shaft73and the inner cylinder wall63and also lift between the outer cylinder wall74and the rotor portion66, pass under of the O ring81, and go into the first path70between the center shaft73and the inner cylinder wall63from a hole (second path)63c.

As described above, when the viscous fluid101and the air move, since the air moves faster than the viscous fluid101, the air does not remain in the accommodation portion91which is formed by the driven rotation member61, the fixing and supporting member71, and the O ring81.

In addition, since a constriction portion70ais provided in the first path70, the speed of the viscous fluid101moving through the first path70is suppressed by the constriction portion70a, and accordingly, it becomes easy to discharge the air outside the accommodation portion91by increasing the moving speed of the air compared with that of the viscous fluid101.

In addition, since a space formed by the outer cylinder wall74, the inner cylinder wall63, and the rotor portion66, that is, a space under the O ring81in the accommodation portion91communicates with the first path70through the hole (second path)63c, the air does not remain inside the accommodation portion91.

As described above, when the bottom of the driven rotation member61is inserted into the fixing and supporting member71, the rotor portion66, as shown inFIG. 15, is inserted into the inside of the outer cylinder wall74rotatably, and the O ring81seals between the outer cylinder wall74and the inner cylinder wall63while allowing the driven rotation member61and the fixing and supporting member71to be relatively rotatable.

The center shaft73is placed inside the inner cylinder wall63, and when the center shaft73passes through the engaging protrusion64to collide with the welding regulating portion65, the engaging protrusion64is inserted into the lock rotation groove73ato be engaged with the lock rotation groove73a.

As shown inFIG. 15, the heat tip H is heated by flowing a current in a status that the driven rotation member61is assembled to the fixing and supporting member71, an upper end of the inner cylinder wall63is melted to be a close portion63dby placing the upper end portion of the inner cylinder wall63in the concave portion c of the heat tip H as indicated by the alternate long and two short dashes line and pressing the heat tip down, the first path70is closed, and then, the heat tip is cooled and removed, and thereby the rotary damper D in a status shown inFIG. 17is acquired. Then, the assembly is completed.

Next, an example of the attachment of the rotary damper D will be described.

As shown inFIG. 17, the rotary damper D is attached to the attached plate E by pinching the attached plate E between the holding claw76aand the holding protrusion77using a hole which is provided in the attachment plate E, that is a hole having the same circular shape as the outer cylinder wall74of the fixing and supporting member71having a notch into which the attachment portion75can be inserted at opposing positions of an outer circumference at 180 degrees.

Next, the operation of the rotary damper will be described.

At first, when the driven rotation member61is rotated by the rotation of the gear portion62which is interlocked with a gear, a rack, or the like, the rotation of the driven rotation member61is damped by a viscous resistance and a shearing resistance of the viscous fluid101interposed between the driven rotation member61and the fixing and supporting member71.

Accordingly, the gear portion62of the driven rotation member61damps the rotation or movement of the gear, the rack, or the like which is interlocked with the driven rotation member, so that the gear, the rack, or the like is slowly rotated or moved.

As described above, according to a sixth embodiment of the present invention, since a first path70is provided between the center shaft73and the inner circumference of the inner cylinder wall63while allowing the accommodation portion91to communicate with its outside and a hole (second path)63cwhich allows the bottom side of the O ring81inside the accommodation portion91to communicate with the first path70is provided in the driven rotation member61, the air located under the O ring81inside the accommodation portion91in which air can be easily collected can be discharged through the hole (second path)63cand the first path70outside the accommodation portion91.

Accordingly, the non-uniformity of damping torque can be reduced by decreasing the remaining air inside the accommodation portion91.

In addition, since the first path70that allows the accommodation portion91defined between the driven rotation member61and the fixing and supporting member71to communicate with its outside and a constriction portion70ais provided in the first path70, the speed of the viscous liquid101moving through the first path70is reduced by the constriction portion70a. Accordingly, the air can be easily discharged outside the accommodation portion91by increasing the relative moving speed of the air with respect to that of the viscous fluid.

Accordingly, the non-uniformity of damping torque is reduced by reducing the air remaining in the accommodation portion91.

In addition, since a plurality of the constriction portions70aare provided in the first flow70in a direction that the viscous liquid101flows, the speed of the viscous liquid101moving through the first path70is reduced further by the plurality of constriction portions70a. Accordingly, the air can be more easily discharged outside the accommodation portion91by further increasing the relative moving speed of the air with respect to that of the viscous fluid101.

Accordingly, the non-uniformity of damping torque can be reduced more by further decreasing the remaining air inside the accommodation portion91.

In addition, since the top face (bottom face68aof the protrusion inclination portion68) forming the first path70is formed to be an inclination increasing its height, the air is lifted along the top face, and accordingly, it becomes much easier to discharge the air outside the accommodation portion91.

Accordingly, the non-uniformity of damping torque can be reduced much more by even further decreasing the remaining air inside the accommodation portion91.

In addition, since the first path70is closed after the assembly, an outlet of the viscous liquid101is removed, and accordingly, the leakage of the viscous liquid101outside the accommodation portion91can be prevented.

In the embodiments described above, when the driven rotation member11or61and the fixing and supporting member21or71are assembled, an example of a configuration in which the gap regulating portion (welding regulating portion19or35) for regulating a gap between the driven rotation member11or61and the fixing and supporting member21or71in a direction of the rotation shaft around which the driven rotation member11or61and the fixing and supporting member21or71relatively rotate is provided to the driven rotation member11or61is represented, but as shown inFIGS. 4 and 6, an upper stair portion23uof the outer cylinder wall23which the holding flange portion13contacts may be configured as the gap regulating portion.

In addition, although an example of a complimentary engaging portion in which an engaging protrusion18or64is provided in the inner cylinder wall16or63and a lock rotation groove26or73ais provided in the center shaft25or73is represented, the complimentary engaging portion may have a configuration in which a lock rotation groove is provided in the inner cylinder wall and an engaging protrusion is provided in the center shaft.

In addition, although an example in which the sealing member is an O ring31or81is represented, but the sealing member may have a concave portion and a convex portion which can relatively rotate and the convex portion may be two-color molded using soft material.

In addition, the through hole25tin the fifth embodiment may be provided in the center shaft25or73in one of the first to fourth and sixth embodiments, and the through hole25tmay be closed by welding after being assembled.

When an amount of the flexibility of the engaging claw23iis required, slits corresponding to left/right sides of the engaging claw23imay be provided in an upper portion of the outer cylinder wall23A which the O ring31seals by pressing, so that a part of the outer cylinder wall23is bent.

In addition, although the engaging portion has a configurations in which an engaging protrusion18or64and a lock rotation groove26or73aare included (the first, fourth, fifth, and sixth embodiments), a holding flange portion13A and an engaging claw23iare included (the second embodiment), or an engaging claw13cand a rotation lock portion23oare included (the third embodiment) is represented, any one of the engaging portions may be used.

In addition, although an example in which a second path (hole63c) which allows the bottom of the O ring81of the accommodation portion91to communicate with the first path70is provided in a part of the inner cylinder wall63above the rotor portion66is represented, the second path may be provided to extend to the upper end portion of the rotor portion66or be provided in the upper end of the rotor portion66.

In addition, although an example in which the rotor portion66includes a flange portion67and a protrusion inclination portion68and the bottom face68aof the protrusion inclination portion68is configured to be an inclination face is represented, the whole rotor portion66may be the protrusion inclination portion and the bottom face of the protrusion inclination portion may be a cone face increasing its height toward a center (inner cylinder wall63).

In addition, although an example in which the upper end portion of the inner cylinder wall63is closed, the upper end portion of the inner cylinder wall63may not be closed when the viscous fluid101does not leak from the first path70to the outside of the fixing and supporting member71.

In addition, although an example in which the constriction portion70aof the first path70is provided in the stair portion12aof the bottom wall72is represented, the constriction portion may be provided in the first path70by configuring the inner bottom face of the bottom wall72to be a cone face and providing a stair portion in the protrusion inclination portion68.

In addition, the sixth embodiment of the present invention may be applied to a general rotary damper including a fixing and supporting member main body having a concave portion in the shape of a cylinder, a fixing and supporting member having a concave portion in the shape of a cylinder which has a cap closing an opening face of the fixing and supporting member and having its periphery sealed to the fixing and supporting member main body to be attached, a viscous fluid which is filled in the fixing and supporting member, a driven rotation member in which a rotor portion is inserted into the viscous fluid inside the fixing and supporting member rotatably and a center shaft is extruded outward (outside the fixing and supporting member) from the center of the cap and an O ring which prevents the leakage of the viscous liquid from between the outside of the center shaft (driven rotation member) and the inside of the cap (fixing and supporting member).

As described above, when the sixth embodiment of the present invention is applied to the general rotary damper, a first path having an L-shaped or T-shaped longitudinal section face which is formed by a horizontal hole (a hole in right/left directions corresponding to the second path63c) and a vertical hole (a hole in up/down directions) disposed in a side upper than a horizontal hole of a hole (a hole in the up/down directions) of the inner cylinder wall63and communicating with the horizontal hole is provided as a center shaft, and the first path is closed when or after being assembled.

INDUSTRIAL APPLICABILITY

A rotary damper of the invention can be easily assembled by decreasing the remaining air in the accommodation portion and reducing the non-uniformity of damping torque (keeping the precision of the torque constant).