GB2246185A

GB2246185A - Rotary damper

Info

Publication number: GB2246185A
Application number: GB9108239A
Authority: GB
Inventors: Kazuyoshi Ohshima; Tatsuya Hayakawa
Original assignee: Sugatsune Kogyo Co Ltd
Current assignee: Sugatsune Kogyo Co Ltd
Priority date: 1990-05-23
Filing date: 1991-04-17
Publication date: 1992-01-22
Anticipated expiration: 2011-04-17
Also published as: GB9108239D0; GB2246185B; KR930006151B1; KR910019561A

Abstract

A damper for a foldable bed or the like comprises a cylindrical casing formed with a protrusion 1d on its inner peripheral wall surface 1c and a rotary blade 4b rotatably mounted in the casing. The rotary blade is forwardly or reversely rotatable through a predetermined angle by a rotational shaft 4 connected to a bed or the like. A high viscosity fluid D is provided in the casing and the rotary blade 4 is formed with a pair of passages 5, 6 having respective check valves which are alternately opened or closed by the forward or reverse rotation of the blade 4b. Two chambers A, B divided by the protrusion 1d in the casing are connected by a pair of passages 10, 11 having respective check valves 12, 13 for alternately opening and closing the passages. Fluid tow rate regulating valves 14, 15 are respectively disposed in the passages 10, 11. Thus the damper force can be regulated by altering the flow rate between the two chambers A, B. <IMAGE>

Description

DAMPER FOR FOLDABLE BED AND THE LIKE BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a rotary orifice damper utilizing viscous shearing resistance force of polymer viscous fluid or other high viscous fluid and, more particularly, to a damper for a foldable bed and the like which can lightly and slowly pivotally rotating a foldable bed in which a spring force is energized in a folding direction toward a horizontal state or an erected state, a flap door, a lift coat hanger, etc., by suitably generating a braking force against the rotating torque of the bed and which can further prove to smoothly open or close the foldable bed or the like (toward the horizontal state or the erected state) even if unintentional external overload force is applied to the bed.

Description of the Prior Art A rotary orifice damper has been already known in which an interval between the outer peripheral surface of a rotary member arranged in a casing and the inner peripheral wall surface of the casing is varied toward a rotating direction by using high viscosity fluid to increase a resistance force of the high viscosity fluid by utilizing the variation of the interval.

However, in the conventional rotary orifice damper, a damper force is acted only when the damper is rotated normally or reversely with respect to a rotational shaft, or a damper force is acted when the damper is rotated in both normal and reverse directions. In both cases, the damper force is acted in the entire rotating range of the rotational shaft.

Therefore, the damper force is not acted in a certain rotating angle range of the entire normal or reverse rotating direction of the rotational shaft.

Thus, a function of generating the damper force only in other predetermined rotating angle range cannot be obtained. As a result, there arises a problem in which the damper cannot be used in a wide range.

SUMMARY OF THE iNVENTION A primary object of the present invention is to provide a damper for a foldable bed which can eliminate the problems of the above-described conventional rotary orifice damper and which can arbitrarily set an angle of acting a damper force and an angle of inhibiting the damper force in both normal and reverse rotations and can regulate the damper force at any time by providing a variation in an interval between the inner peripheral wall surface of a casing and the outer periphery of a rotary blade having a pair of check valves supported to be normally or reversely rotated only at a predetermined angle in the casing.

Another object of the present invention is to provide a damper for a foldable bed which can eliminate a problem which cannot be solved by a first aspect of the invention.

In other words, in case of a foldable bed, if its mattress is heavier than required or a children plays on the bed, the damper cannot solve an abrupt opening or closure of the bed to cause a serious danger or the bed to be damaged at the pivots and the like of the bed.

Accordingly, the other object of the invention is to provide a damper for a foldable bed which can automatically regulate to increase a damper force and arbitrarily regulate the damper force to cope with an excessively heavy state by closing a communication hole provided with a movable valve suitably by the pressure of high viscous fluid when an excessive rotary force is applied to a rotary blade.

In order to achieve the above-described and other objects of the present invention, according to first aspect of the invention, there is provided a damper for a foldable bed and the like comprising a rotary blade having an outer diameter of a long axis direction smaller than the inner diameter of a casing of a cylindrical shape having a protrusion on the portion of the inner peripheral wall surface thereof and arranged in the casing to be normally or reversely rotatable at a predetermined angle integrally with a rotational shaft rotatable together with the bed or the like, high viscous fluid provided in said casing being provided between said casing and the rotary blade, a pair of passages respective having check valves to be reversely opened or closed by the normal or reverse rotation of said rotary blade and passed to be formed in the rotating direction in said rotary blade, protrusion walls provided at the positions on the outer peripheral surface of said rotary blade at the initial time of normal or reverse rotation of said rotational shaft, two chambers passed adjacent to the projection partitioned in the casing by said protrusion, and a pair of passages having check valves for opening and closing reversely the passages thereof and high viscous fluid flowrate regulating valves and provided in the protrusion to communicate the adjacent two chambers.

According to another embodiment of second aspect of the present invention, there is also provided a damper for a foldable bed and the like comprising a rotary blade having an outer diameter of a long axis direction smaller than the inner diameter of a casing of a cylindrical shape having a protrusion on the portion of the inner peripheral wall surface thereof and arranged in the casing to be normally or reversely rotatable at a predetermined angle integrally with a rotational shaft rotatable together with the bed or the like, high viscous fluid provided in said casing being provided between said casing and the rotary blade, a pair of passages respective having check valves to be reversely opened or closed by the normal or reverse rotation of said rotary blade and passed to be formed in the rotating direction in said rotary blade, protrusion walls provided at the positions on the outer peripheral surface of said rotary blade at the initial time of normal or reverse rotation of said rotational shaft, an upper passage passed to communicate to chambers partitioned adjacent to said protrusion in said casing, a lower passage provided to communicate with said upper passage, both ends thereof and on the way thereto by connection holes, regulating threaded shafts passed through both ends of said upper passage and said lower passage, movable valves arranged movably to said connection hole side by the high viscous fluid in said lower passage to be inserted thereto1 a pair of control valves supported at one ends thereof to the regulating screws engaged into a cover plate of said casing and provided with springs energized in a direction for resisting against the normal or reverse flow of the high viscous fluid to said movable valves, and a regulating valve for converting the flowing direction of the high viscous fluid to close the downstream side of the high viscous fluid in said upper passage at the time of normal or reverse rotation said rotary blade.

Operation According to the first aspect of the embodiment of the invention, the rotational shaft and the rotary blade are started to be rotated in one direction by applying a rotary force of an external force to the rotational shaft.

Thus, the pressure of the high viscous fluid in the one chamber, i.e., the first chamber in the casing is raised and hence the check valve of one passage of the rotary blade and the check valve of the one passage of the protrusion are closed by the high viscous fluid so that the high viscous fluid does not flow to the passages but forcibly opens the check valve of the other passage of the protrusion to flow through the passage to the other chamber, i.e., the second chamber.

On the other hand, the high viscous fluid in the first chamber passes through the interval between the one outer peripheral surface of the rotary blade and the casing to flow between the short axis direction side of the rotary blade and the casing. Then, the resultant high viscous fluid forcibly opens the check valve of the other passage of the rotary blade to pass through the passage and to pass through the interval between the other outer peripheral surface of the rotary blade and the casing to the second chamber so that the damper force is not acted.

When the rotary blade is continuously rotated in one direction as described above, the one outer peripheral surface of the rotary blade is approached to the one protrusion wall of the casing to reduce the interval therebetween. The damper force is started to act from the rotating angle starting in the variation in the interval therebetween, and the damper force is increased up to the maximum rotating angle until the rotational shaft and the rotary blade are stopped.

Then, when an external force is applied as a reverse rotating force to the rotational shaft, the pressure of the second chamber of the casing is raised by the rotations of the rotational shaft and the rotary blade. Therefore, the check valves of the other passages of the rotary blade and the protrusion are closed by the high viscous fluid so that the high viscous fluid does not flow to the passages, but the high viscous fluid forcibly opens the check valve of the one passage of the protrusion and to flow through the passage to the first chamber.

Further, on the other hand, the high viscous fluid in the second chamber passes through the interval between the other outer peripheral surface of the rotary blade and the casing. The resultant high viscous fluid forcibly opens the check valve of the one passage of the rotary blade, and passes through the passage and the interval between the one outer peripheral surface of the rotary blade and the casing to the first chamber so that the damper force is not acted.

As described above, when the rotary blade is continuously rotated reversely, the other outer peripheral surface of the rotary blade is approached to the other protrusion wall of the casing to reduce the interval therebetween, the damper force is started to act from the rotating angle starting in variation in the interval therebetween, and the damper force is then increased to the maximum at the maximum rotating angle where the rotations of the rotational shaft and the rotary blade are stopped.

As described above, the damper force is acted only in a predetermined angle range even in both normal and reverse rotations of the rotational shaft and the rotary blade.

Further, the flow rates of the high viscous fluids of the passages can be regulated by the regulating valves provided in the two passages of the protrusion, thereby regulating the damper force in both the normal and reverse rotating directions.

According to the other embodiment of the second aspect of the present invention, the operation will be described.

When one rotating force of an external force is first applied to the rotational shaft, the rotational shaft and the rotary blade are started to rotate in the same direction as described above.

As described above, the pressure of the high viscous fluid in the first chamber in the casing is raised, the check valve of the one passage of the rotary blade and the regulating valve of the protrusion are closed by the high viscous fluid, and the one passage of the rotary blade and the downstream side of the upper passage of the protrusion are respectively closed so that the high viscous fluid does not flow to the passages. However, the high viscous fluid passes the upstream side of the upper passage of the protrusion to flow through the interval between the connection hole of one end and the movable valve and the connection hole on the way to the lower passage and further through the interval between the connection hole of the other end and the movable valve to the downstream side of the upper passage and then to the other chamber.

On the other hand, the high viscous fluid in the first chamber passes through the interval between the outer peripheral surface of the rotary blade and the casing to forcibly open the check valve in the other passage of the rotary blade to pass through the passage and to also pass through the interval between the other outer peripheral surface of the rotary blade and the casing to the other chamber so that the damper force is not acted.

As described above, when the rotary blade is continuously rotated in one direction, the interval between the outer peripheral surface of the rotary blade and the inner wall surface of the casing is varied at a small value. Therefore, the damper force is started to act from the rotating angle where the interval is started to be varied, and the damper force is increased to the maximum rotating angle until the rotations of the rotational shaft and the rotary blade are stopped.

As described above, since the movable valve is pressed to the opposite side to the connection hole by the spring when the rotary blade is rotated by the ordinary rotary force, the high viscous fluid flows through the interval between the connection hole and the movable valve. However, when an excessive rotary force is applied to the rotational shaft and the rotary blade, the pressure of the high viscous fluid in the first chamber is raised more than the pressure at the normal value. When the pressure of the high viscous fluid at this time overcomes the spring force, the movable valve of the other control valve is moved against the spring force to close the connection hole.

Therefore, tne high viscous fluid does not flow to the downstream side of the upper passage. Thus, the damper force is increased.

The damper force at the time of ordinary rotation can be controlled by regulating the interval between the connection hole and the movable valve by the control valve, and the damper force when the excessive rotary force is applied can also be regulated by varying the spring force by the regulating screw.

Then, when the reverse rotary force of the external force to that in the above case is applied to the rotational shaft and the rotational shaft and the rotary blade are rotated in the same direction, the high viscous fluid flows, similarly to the above, from the second chamber to the first chamber. In this case, when the excessive rotary force is applied, the movable valve of the one control valve is closed similarly to the above case, the damper force is increased, and the damper force at that, time can be similarly regulated to the above case.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects as well as advantageous features of the invention will become apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings.

Fig. 1 is a longitudinal sectional view showing an embodiment according to first aspect of a damper for a foldable bed of the present invention; Fig. 2 is an exploded perspective view of the embodiment; Figs. 3(a), 3(b), 3(c), 3(d), 3(e) and 3(f) are explanatory views of operating states at the time of normal and reverse rotations of the embodiment; Fig. 4 is a lateral sectional view showing another embodiment according to second aspect of a damper for a foldable bed of the present invention; Fig. 5 is a longitudinal sectional view taken along the line V-V in Fig. 4; Fig. 6 is a longitudinal sectional view of the damper illustrating a state that a communication hole is closed upon rising of a movable valve of one control valve by high viscosity fluid; Fig. 7 is a longitudinal sectional view taken along the line VII-VII in Fig. 4;; Fig. 8 is a lateral sectional view of the damper illustrating the stopping position of a rotary blade; and Fig. 9 is an explanatory view showing a damper ON range and a damper OFF range with respect to the opening angle of the foldabie bed attached with the dampers according to first and second aspect of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment a damper of first aspect of the present invention will now be described with reference to the accompanying drawings.

As shown in Figs. 1 to Figs. 3(a) to 3(f), an axial bore Ib is recessed at the center of a bottom wall la of vertical cylindrical casing 1, and a cover plate 2 is liquidtightly secured to an opening of the upper end of the casing 1 with a plurality of screws 3,..

The casing 1 is formed with a projection id from one side portion of the inner peripheral wall surface ic thereof substantially in a sector shape in plane such that the inner peripheral end surface is formed in an arcuate surface to be slidably contacted with a rotational shaft 4 tb be described later.

The rotational shaft 4 is rotatably engaged at a lower end thereof with the axial bore ib of the casing 1, and supported at an upper end thereof to the center of the casing 1 by rotatably passing liquidtightly the shaft 4 through an axial hole 2a perforated at the center of the cover plate 2.

A square shaft 4a is integrally formed at the projection end of the rotational shaft 4 to extend externally from the cover plate 2 through the axial hole la of the cover plate 2, and the pivotal center of a bed (not shown) is engaged fixedly with the shaft 4a to be actuated by a rotary force as an external force.

A rotary blade 4b is symmetrically projected at opposite side to the projection Id of the casing 1 from the center and perpendicularly to the center line of the rotational shaft 4.

The rotary blade 4b is formed in such a manner that the outer diameter 1' is considerably shorter than the outer diameter ss of the long axis direction thereof such that the outer diameter 2 of the long axis direction thereof is shorter than the inner diameter L of the casing 1 and a side space c is formed between the outer periphery and the inner peripheral wall surface ic of the casing in the short axis direction.

Further, the rotary blade 4b is passed with a pair of passages 5 and 6 in the vicinities of both ends of the long axis direction thereof in the rotating direction of the rotary blade 4b, formed with valve seats 5a and 6a in the passages 5 and 6 in the same direction, and arranged with pin-shaped check valves 7 and 8 to be seated on or separated from the valve seats 5a and 6a such that both upper and lower ends of the check valves 7 and 8 are slidably inserted into long holes 5b, 5b and 6b, 6b formed at the upper and lower walls formed with the passages 5 and 6 of the rotary blade 4a toward the rotating direction.Thus, when the rotary blade 4b is normally rotated, the passages 5 and 6 are respectively closed and opened, while when the rotary blade 4b is reversely rotated, the passages 5 and 6 are respectively opened and closed.

Projection walls le and if are respectively projected from the position of the inner peripheral wall surface lc of the casing 1 oppositely to the outer peripheral surface 4c of one end of the rotary blade 4b in the vicinity of one rotating ends of the rotational shaft 4 and the rotary blade 4b and the predetermined position of the inner peripheral wall surface ic opposed to the outer peripheral surface 4d of the other end of the rotary blade 4b in the vicinity of the other rotating end of the rotary blade 4b inwardly in highest height at both sides of the base ends of the projection id of the casing 1 to be formed to be gradually lower toward the circumferential direction. Thus, the inner diameter L of the casing 1 is gradually reduced toward the projection Id side for restricting the rotating angle range of the rotary blade 4b, thereby varying intervals F and G between the inner peripheral wall surface ic of the casing 1 and both the outer peripheral surfaces 4c and 4c of the rotary blade 4b.

As described above, the interior of the casing 1 is divided, in addition to the space C, into a first chamber A and a second chamber B by the projection Id and the rotary blade 4b, and high viscous fluid D in the casing 1 is filled among the casing 1, the rotational shaft 4 and the rotary blade 4b.

A pair of passages 10 and 11 are formed in the circumferential direction of the projection ld of the casing 1 to communicate the first chamber A with the second chamber B, provided with reverse valve seats 10a and 11a in the passages 10 and 11, respectively and arranged with pin-shaped check valves 12 and 13 to be seated on or separated from the valve seats 10a and lla to be alternately opened and closed.

Flowrate regulating valves 14 and 15 are respectively arranged in the passages 10 and 11 at the sides to which high viscous fluids D flow.

The flowrate regulating valves 14 and 15 respectively haver as apparently shown in Fig. 2, square columnar regulating blocks 14a and 15a vertically upwardly or downwardly slidably inserted into square holes 10b and 11b enlarged in the passages 10 and 11, and adjusting screws 14c and 15c threadedly engaged with threaded holes 14b and 15b passed through the centers of the regulating blocks 14a and 15a. The adjusting screws 14c and 15c are respectively supported to the projection Id of the casing 1 to be rotatable through an O-ring 16 to be liquidtightly inserted into mounting holes 1g and ig formed at the projection 1d and inserted at the upper ends thereof into the through holes 1b and lc of the cover plate 2.When the adjusting screws 14c and 15c are rotated normally or reversely, the regulating blocks 14a and 15a are respectively upwardly or downwardly slidably fed thereby to regulate the flow rates of the high viscous fluids in the passages 10 and 11.

Both the passages 10 and 11 are connected to a bypass passage 17 on the way, and, when the regulating valves 14 and 15 are finely regulated, the check valves 12 and 13 may not be disturbed to be closed due to the face that the passages 10 and 11 are evacuated to be negative pressure.

When the damper arranged as described above is used for a foldable bed or the like, the rotational shaft 4 is coupled to the bed, and the casing 1 is mounted at a bed mounting member. For example, when a bed 18 is mounted to be erected at a folding position b1 at 900 of a vertical state as shown in Fig. 9 or to be tilted down at a using position b5 at 0 of a horizontal state, the rotational shaft 4 is coupled to the bed 18 to be rotated in a direction of an arrow E in Fig. 3(a) when the bed 18 is tilted down at the using position bg.

The bed 18 is applied by the force of a spring (not shown) so that the bed 18 is returned toward the folding position bl thereof from the folding position b1 to an angle b3 and the bed 18 is naturally tilted down from the angle b3 to the using position bg.

When the bed 18 is opened from the position at 900 of the vertical state, the rotational shaft 4 is rotated from the position in Fig. 3(a) in a direction of an arrow E, and the rotary blade 4b is started to be rotated in the same direction as the rotational shaft 4, the pressure of the high viscous fluid D in the first chamber A is first raised, the check valves 7 and 13 respectively close the passages 5 and 11 by means of the raised high viscous fluids D so that the high viscous fluids D do not flow the passages 5 and 11.

Then, the high viscous fluid D in the first chamber A flows to the passage 10 to forcibly open the check valve 12 to resultantly flow to the second chamber B and to also flow to the space C through the interval G between the outer peripheral surface 4d of the rotary blade 4b and the inner peripheral wall surface Ic of the casing 1. Thus, the high viscous fluid D flows to the passage 6 to forcibly open the check valve 8 to resultantly flow to the second chamber B and and the high viscous fluid D in the first chamber A flows to the second chamber B through the interval F between the outer peripheral surface 4c of the rotary blade 4b and the inner peripheral wall surface lc of the casing 1.

This state is shown in Fig. 3(b), and the high viscous fluid D flows in the direction of the arrow in Fig. 3(b).

When the rotary blade 4b is further rotated from the position in Fig. 3(b) in the direction of the arrow E in Fig. 3(b), the outer peripheral surface 4d of the rotary blade 4b is approached to the projection wall lf of the casing 1 to reduce the interval G between the outer peripheral surface 4d and the casing 1, thereby varying the interval G. Thus, shearing resistance force of the high viscous fluid is generated from the rotating angle shown in Fig. 3(c) to start to actuate a damper force. Therefore, the damper force is generated from this position shown in Fig. 3(c) to rotate the rotary blade 4b to the position in Fig. 3(d). Then, the rotational shaft 4 and the rotary blade 4b are stopped.

In other words, in Fig. 9, a damper OFF range I for inhibiting the damper force is provided from the position b1 through the angle b2 to the position b3 of the bed 18, and a damper ON range J for generating the damper force is provided from the position b3 through the angle b4 to the position b5 of the horizontal state of the bed 18.

Therefore, the bed 18 is slowly pivotally rotated against the force of the spring from the angle b1 of the vertical state to the angle b3, and slowly tilted down from the angle b3 to the position b5 of the horizontal state by the damper force.

Then, when the bed 18 is pivotally rotated upwardly from the using position b5 of the horizontal state, the rotational shaft 4 and the rotary blade 4b are rotated from the position in Fig. 3(d) in the opposite direction of an arrow H to the above-described direction. Thus, the pressure of the high viscous fluid D in the second chamber B is raised, the high viscous fluids D close the check valves 8 and 12 as shown in Fig. 3(e) to close the passages 6 and 10 so that the high viscous fluids D do not flow to the passages 6 and 10. However, the check valves 7 and 13 are forcibly opened by the raised pressure of the high viscous fluids D so that the high viscous fluids D in the space C and the second chamber B flow to the first chamber A through the passages 5 and 11.

On the other hand, the high viscous fluid D in the second chamber B flows to the first chamber A through the intervals F and G between the outer peripheral surfaces 4c and 4d of the rotary blade 4b and the casing 1.

When the rotational shaft 4 and the rotary blade 4b are rotated in the same direction, the outer peripheral surface 4c of the rotary blade 4b is approached to the projection wall le of the casing 1 to resultantly reduce the interval F between the outer peripheral surface 4c and the casing 1, thereby starting to actuate the damper force from the rotating angle at which the interval G is varied to become the state shown in Fig. 3(f), and returning to the state as shown in Fig. 3(a) to be stopped.

In other words, in Fig. 9, a damper OFF range K for inhibiting the damper force is provided from the position b5 through the angle b4 to the position b3, and a damper ON range L for generating the damper force is provided from the position b3 through the angle b2 to the position b1 of the vertical state.

Therefore, the bed 18 is slowly folded from the position b3 to the folding position bl the vertical state by means of the spring effect and the damper effect against thereto.

In Fig. 9, reference character M denotes a damper according to the embodiment of the present invention, and reference numeral 19 denotes a floor surface.

A damper of another embodiment according to second aspect of the present invention will be described in detail.

As shown in Figs. 4 to 8, a vertical cylindrical casing 1 is recessed, similarly to the embodiment of the first aspect of the invention, with an axial bore 1b at the center of a bottom wall la thereof as shown in Fig. 7, and a cover plate 2 is secured liquidtightly through an O-ring 2a to an opening of the upper end thereof with a plurality of screws 3.

The casing 1 has a projection ld formed substantially in a sector shape in plane with an arcuate surface lh slidably contacted with a hollow rotational shaft 4 of a rotary blade 4b at the inner peripheral end surface thereof at one side of the inner peripheral wall surface lc thereof on a thick portion li formed partly on the inner peripheral wall surface lc to be superposed fixedly with a groove plate lj made of a separate member.

The rotational shaft 4 is rotatably mounted at a lower end thereof with a bearing collar 4e and a bearing 4f liquidtightly through an O-ring 4g in an axial bore lb, and rotatably supported at an upper end thereof to be mounted with a bearing collar 4e' and a bearing 4f' liquidtightly through an O-ring 4g' in the axial hole 2a formed at the center of the cover plate 2 to the center of the casing 1. Further, the core 4' of the rotational shaft 4 of a polygonal shape is engaged with a polygonal hole 4 formed through the center of the rotational shaft 4, and a pivotal center of a bed (not shown) or the like is secured to the projection end projecting upwardly from the core 4' of the rotational shaft 4 to be applied by a rotary force of an external force by means such as engaging or the like.

A rotary blade 4b is radially integrally projected from the portion of the outer peripheral surface of the rotational shaft 4, similarly to the embodiment of the first aspect of the invention described above. The rotary blade 4b is formed such that the radius r thereof is smaller than the radius R of the inner peripheral wall surface Ic of the casing 1, a recess 4i of substantially V-shaped section is formed at the center of the outer peripheral surface thereof, and a space c is formed, similarly to the embodiment of the first aspect of the invention, between the recess 4i and the inner peripheral wall surface lc of the casing 1.

The rotary blade 4b has a pair of passages 5 and 6 passed therethrough to be opened at one ends thereof with the recess 4i thereof in the rotating direction of the rotary blade 4b in the vicinity of both ends in the rotating direction thereof, valve seats 5a and 6a formed symmetrically in the respective passages 5 and 6, and pin-shaped check valves 7 and 8 so inserted slidably in long holes 5b, 5b and 6b, 6b formed at the upper and lower walls for forming the passages 5 and 6 thereof at both ends thereof toward the rotating direction to be seated on or separated from the valve seats 5a and 6a, similarly to the embodiment of the first aspect of the invention. Thus, the passages 5 and 6 are alternatively closed and opened when the rotary blade 4b is rotated normally and reversely.

Projection walls le and lf are respectively projected inwardly in highest height at both sides of the base end of the projection id at a position on the inner peripheral wall surface lc of the casing oppositely to the outer peripheral surface 4c of one end of the rotary blade 4b in the vicinity of the one rotating ends of the rotational shaft 4 and the rotary blade 4b and at a position thereon oppositely to the outer peripheral surface 4d of the other end of the rotary blade 4b in the vicinity of the other rotating end of the rotary blade 4b. Thus, the projection walls le and if are formed to be gradually lowered toward the circumferential direction.In this manner, the radius R of the casing 1 is formed to be gradually reduced toward the projection id side for restricting the rotating angle range of the rotary blade 4b to vary intervals F and G between the inner peripheral wall surface Ic of the casing and the outer peripheral surfaces 4c, 4d of the rotary blade 4b. Thus, the interior of the casing 1 is divided, in addition to the space C, into a first chamber A and a second chamber B by the projection id and the rotary blade 4b, and high viscous fluid D in the casing 1 is filled among the casing 1, the rotational shaft 4 and the rotary blade 4b, substantially similarly to the embodiment of the first aspect of the invention.

In the damper according to the embodiment of the second aspect of the invention, the content of the arrangement to be described below is different from the embodiment of the first aspect of the invention. An upper passage 20 is formed to communicate the first chamber A with the second chamber B in the projection id in the circumferential direction, and a lower passage 21 is formed to communicate the both circumferential ends and a substantially intermediate portion with the upper passage 20 through connection holes 22, 23 and 24.

More specifically, in the embodiment of the second aspect as shown in Figs. 4 to 8, the upper passage 20 is formed by liquidtightly closing an opening at the upper end of the groove recessed on the upper surface of the groove plate lj by the cover plate 2, while the lower'passage 21 is formed by liquidtightly closing an opening at the upper end of the groove 21a recessed on the upper surface of the thick portion li of the casing by the groove plate lj, and the connection holes 22, 23 and 24 are formed on the groove plate lj.

A pair of control valves 25 and 26 are arranged at both ends of the upper and lower passages 20 and 21 for increasing damper forces, when the rotational shaft 4 and the rotary blade 4b are rotated normally or reversely to be described later and excessive external forces are applied thereto, in response to the excessive external forces and for arbitrarily regulating the speeds of the rotational shaft 4 and the rotary blade 4b at the ordinary time, and a regulating valve 27 is arranged at the position of the hole 23 at the intermediate in the passage 20 for converting the flowing direction of the high viscous fluid D.

The pair of control valves 25 and 26 are constructed as below. The control valves 25 and 26 respectively have regulating threaded shafts 25a and 26a arranged substantially perpendicularly in both the upper and lower passages 20 and 21 to be axially slidably inserted into the connection holes 22 and 24 and axial holes 28 and 29 projected in the casing 1, and speed regulating screws 25b and 26b engaged liquidtightly into threaded holes 30 and 31 perforated coaxially with the axial holes 28 and 29 through O-rings 32 and 33 for axially movably regulating the regulating threaded shafts 25a and 26a.

The pair of control valves 25 and 26 further respectively have movable valves 25c and 26c arranged axially slidably on the regulating threaded shafts 25a and 26a in the lower passage 21 to open or close the connection holes 22 and 23 from below, spring force regulating screws 25d and 26d liquidtightly engaged with threaded holes 34 and 35 passed along the extension lines of the connection holes 22 and 23 at the cover plate 2 through O-rings 36 and 37 to support the upper ends of the regulating threaded shafts 25a and 26a, and springs 25f and 26t mounted on the regulating threaded shafts 25a and 26a in the state that the lower ends thereof are abutted against the upper ends of the movable valves 25c and 26c and the upper ends thereof are abutted against the lower ends of the regulating screws 25d and 26d for energizing the movable valves 25c and 26c in the direction for pressing the movable valves 25c and 26c on annular seats 25e and 26e of the regulating threaded shafts 25a and 26a.

Therefore, when the rotational shaft 4 and the rotary blade 4b are ordinarily rotated, the connection holes 22 and 24 are opened. When excessive rotary forces are applied to the rotational shaft 4 and the rotary blade 4b so that the pressure of the high viscous fluid overcomes the forces of the springs 25f and 26f, the movable valves 25c and 26c are lifted against the spring forces, and the connection holes 22 and 24 are closed. The varying states of the movable valves 25c and 26c against the flow of the high viscous fluid D, i.e, the damper forces can be regulated by altering the spring forces by the regulating screws 25d and 26d.

On the other hand, the regulating valve 27 has two valve seats 27a and 27b opposed at front and rear positions corresponding to the connection hole 23 in the upper passage 20, and a pin-shaped check valve 27c to be seated on or separated from the valve seats 27a and 27b. Both ends of the check valve 27c are arranged to be inserted into grooves 27d and 27d formed in long length longitudinally in the upper passage 20 at both sidewalls for forming the upper passage 20 as apparently shown in Fig. 4.

When the rotary blade 4b is rotated normally or reversely, the downstream side of the high viscous fluid in the flowing direction is closed, the upstream side bf the high viscous fluid is communicated with the lower passage 21 through the connection passage 23, and the high viscous fluid flows in a direction of an arrow in Fig. 6 or in a reverse direction thereto. Here, the upstream side of the passage 20 means the side to which the high viscous fluid flows from the first chamber A when the rotary blade 4b is rotated in the direction of an arrow E in Fig. 4, and the downstream side of the passage 20 means the side to which the high viscous fluid flows out to the second chamber B.Therefore, the upstream side and the downstream side of the upper passage 20 are varied according to the rotating direction of the rotary blade 4b, and the check valve 27c is operated to close the inlet of the downstream side of the passage 20.

When the damper is employed in a foldable bed or the like, the rotational shaft 4 is coupled to the bed, and the casing 1 is mounted at a bed mounting member.

In a case where a bed 18 is, for example, mounted to be erected to a folding position bl of a vertical state (900) in Fig. 9 and to be tilted down to a using position b5 of a horizontal state (0 ), when the bed 18 is tilted down to the using position bg, the bed 18 is coupled to the rotational shaft 4 to rotate the rotational shaft 4 and the rotary blade 4b in the direction of the arrow E in Figs. 4 and 8.

Here, the bed 18 is, as was described with respect to the embodiment of the first aspect of the invention, is applied by a force for returning the bed 18 in the direction of the folding position b1 from the folding position b1 to the angle b3 in Fig. 9, and naturally tilted down from the position b3 to the using position b5 of the horizontal state.

When the bed 18 is opened from the folding position b1 and the rotational shaft 4 and the rotary blade 4b are started to be rotated from the position indicated by two-dotted broken lines in Fig. 8 in the direction of the arrow E in Fig. 8, the pressure of the high viscous fluid in the first chamber A is first raised, similarly to the embodiment of the first aspect of the invention as described above, the check valve 7 closes the passage 5 with the high viscous fluid, the check valve 27c of the regulating valve 27 closes the downstream side inlet of the upper passage 20, and the high viscous fluid D does not flow to the passage 5.

Therefore, the high viscous fluid flows to the space c through the interval G between the outer peripheral surface 4d of the rotary blade 4b and the inner peripheral wall surface lc of the casing 1, the high viscous fluid flows to the passage 6 to forcibly open the check valve 8, then flows to the second chamber B, and the high viscous fluid in the space c similarly flows to the second chamber B through the interval F between the outer peripheral surface 4c of the rotary blade 4b and the inner peripheral wall surface lc of the casing 1.

On the other hand, the high viscous fluid D flowing from the first chamber A to the upper passage 20 flows to the lower passage 21 through the interval between the connection hole 22 and the movable valve 25c since the movable valve 25c is pressed down by the spring 25f of the one control valve 25, and the high viscous fluid D also flows from the connection hole 23 of the intermediate portion to the lower passage 21.

Further, the high viscous fluid of the lower passage 21 flows to the downstream side of the upper passage 20 through the interval between the connection hole 24 of the other control valve 26 and the movable valve 26c, and then flows to the second chamber B.

When the rotary blade 4b is further rotated in the direction of the arrow E in Fig. 9, the outer peripheral surface 4c of the rotary blade 4b is approached to the projection wall le of the casing 1, the interval F between the outer peripheral surface 4c of the rotary blade 4b and the casing 1 is reduced, the interval F is thus varied. Therefore, the shearing resistance force of the high viscous fluid is increased thereby to act the damper force. Thus, the rotational shaft 4 and the rotary blade 4b is eventually rotated to the positions indicated by solid lines in Fig. 8, and then stopped.More specifically, in Fig. 9, a damper OFF range I for inhibiting the damper force is provided from the position b1 of the folding position to the angle b3 through the angle b2 in Fig. 9, similarly to the embodiment of the first aspect of the invention described above, a damper ON range J for generating the damper force is provided through the angle b3 to the using position b5 of horizontal state via the angle b4. Therefore, the bed 18 is slowly rotated from the folding position b1 to the angle b3 against the spring force, and then slowly tilted down from the angle b3 to the using position bs of the horizontal state by the damper force.

Then, when the bed 18 is rotated upward from the using position b5 of horizontal state, the rotational shaft 4 and the rotary blade 4b are pivotally rotated oppositely to the above case from the position indicated by solid lines in Fig. 8 by the pivotal rotation of the bed 18 in the direction of an arrow H in Fig. 8, the check valve 8 is closed by the high viscous fluid to close the passage 6, and the high viscous fluid does not flow in the passage 6. However, since the other check valve 7 is forcibly opened, the high viscous fluids in the space c and the second chamber B flow into the first chamber A through the passage 5. Further, on the other hand, the high viscous fluid in the second chamber B flows to the first chamber A through the intervals G and F between the outer peripheral surfaces 4d, 4c of the rotary blade 4b and the casing 1.At this time, the high viscous fluid in the second chamber B flows from the opposite side to that in the case as described above to the upper passage 20. Thus, the check valve 27c of the regulating valve 27 is pressed by the high viscous fluid to move from the position leftwardly in Figs. 5 and 6 to close the inlet at the downstream side of the upper passage 20.

As described above, the high viscous fluid flows from the passage disposed at the upstream side of the upper passage 20 to the lower passage 21 through the interval between the movable vale 26c of the one control valve 26 and the connection hole 24 and the connection hole 23 of the intermediate portion, further flows through the interval between the movable valve 25c of the other control valve 25 and the connection hole 22 to the downstream side of the upper passage 20, and then flows to the first chamber A.When the rotational shaft 4 and the rotary blade 4b are rotated in the same direction, the outer peripheral surface 4c of the rotary blade 4b is approached to the projection wall if of the casing 1, both the intervals are reduced, similarly to the embodiment of the first aspect of the invention as described above, the damper force starts acting, the rotational shaft 4 and the rotary blade 4b are rotated to the positions indicated by two-dotted broken lines in Fig. 8, and then stopped.

As a result, in Fig. 9, a damper OFF range J for inhibiting the damper force is provided from the using position b5 of the horizontal state of the bed 18 to the angle b3 through the angle b4, and a damper ON range for generating the damper force is provided from the angle b3 to the folding position bl of the vertical state through the angle b2 of the bed 18. Thus, the bed 18 is slowly folded in the folding position from the position b3 to the folding position bl of the vertical state by the spring effect and the damper effect.

If mats are stacked in number more than required on the bed 18 or a children is risen on the bed 18 so that a rotating force due to an excessive load is applied to the rotational shaft 4 when the bed 18 is opened from the folding position indicated by the b1 in Fig. 9 to the using position b5 of the horizontal state, the pressure of the first chamber A becomes more than that at the ordinary time so that the flow of the high viscous fluid is accelerated such that the pressure overcoming the spring force is applied to the one control valve 26 Then, the movable valve 26c is lifted against the spring force, the connection hole 24 is closed as shown in fig. 6, and the high viscous fluid fails to flow the passage flowing from the lower passage 21 to the second chamber B through the connection hole 24.

Therefore, the damper force is further increased, and the bed 18 is not abruptly opened, but slowly opened to the using position b5 of the horizontal state.

If the bed 18 is vigorously closed to the using position bg, an excessive rotating force is applied to the rotational shaft 4. However, in this case, the movable valve 25c of the other control valve 25 is lifted against the spring force to close the connection hole 22. Therefore, the high viscous fluid does not flow from the lower passage 21 to the first chamber A thereby to increase the damper force. Thus, the bed 18 is not abruptly closed, but can be slowly shifted to the folding state.

As described above, the connection holes 22 and 24 are respectively opened and closed or automatically regulated in the opening degree in response to the pressurizing state of the high viscous fluid to the movable valves 25c and 26c, thereby regulating the damper force. The movable valves 25c and 26c can be also regulated by regulating the engaging amounts of the regulating screws 25d and 26d to alter the spring force.

Since the damper according to the embodiment of the first aspect of the present invention is constituted as described above, the damper force can be acted only at the arbitrary angle in both normal and reverse pivotal rotations by specifying the position where the intervals between the inner peripheral wall surface of the casing and the outer peripheral surface of the rotary blade is varied, the damper force of an unnecessary range can be eliminated in the rotating angle range to act the damper force only in the necessary range by providing the pair of passages for reversely opening and closing by the rotary blade, the damper force can be regulated in the respective normal and reverse pivotal rotations by providing the regulating valves in the pair of passages with the check valves reversely opened and closed in communication with the first and second chambers in the casing, the damper force can be further regulated by specifying the above-described interval, and the damper force can solve the requirement by specifying the interval.

Therefore, when the rotational shaft is connected to the foldable bed or the like and the bed is so mounted as to apply the spring force together with the damper force in the folding direction of the bed, the bed can be lightly pivotally rotated by the spring effect from the position at 900 of the bed folding state to a predetermined angle. Further, the bed can be slowly and smoothly tilted down from the predetermined angle to the position at 0 of the using state by the viscous resistance force of the high viscous fluid, and the bed can be slowly and smoothly pivotally rotated to be folded by the spring effect and the damper effect from the predetermined angle to the position at 900.

Since the damper of the embodiment according to the second aspect of the invention is constructed as described above, the damper can not only perform the effect similarly to that according to the embodiment of the first aspect of the invention, but also the regulating valve closes the downstream side of the upper passage by the pressure of the high viscous fluid flowing from the first chamber or the second chamber in the casing to the upper passage by the rotations of the rotational shaft and the rotary blade to guide the high viscous fluid to the lower passage, the movable valve is effected by the pressure of the high viscous fluid in the lower passage thereby to automatically control to regulate the interval to the connection hole and to open or close the connection hole in response to the rotary force to be applied to the rotational shaft.

As a result, the damper force can be regulated in both the normal and reverse rotations of the rotational shaft and the rotary blade. Further, since the operation of the movable valve due to the high pressure of the high viscous fluid can be regulated by altering the spring force by the position regulating screw of the movable valve by the regulating threaded shaft, the damper force can be controlled for various requirements.

Therefore, even if the mats on the bed are heavy or a children rises on the bed when the bed is opened from the folding state to the position of the using state if the rotational shaft or the casing is connected to the foldable bed or the like to mount the bed to be applied by the spring force together with the damper in the folding direction of the bed, of even if the bed is reversely vigorously closed from the using state position to the folding state position, the damper force is increased by closing the movable valve by the high pressure of the high viscous fluid to resist against the unintentional heavy state of the bed at the time of opening or closing and thereby to always slowly and smoothly pivotally rotate the bed safely.

Claims

1. A damper for a foldable bed and the like comprising a rotary blade having an outer diameter of a long axis direction smaller than the inner diameter of a casing of a cylindrical shape having a protrusion on the portion of the inner peripheral wall surface thereof and arranged in the casing to be normally or reversely rotatable at a predetermined angle integrally with a rotational shaft rotatable together with the bed or the like, high viscous fluid provided in said casing being provided between said casing and the rotary blade, a pair of passages respective having check valves to be reversely opened or closed by the normal or reverse rotation of said rotary blade and passed to be formed in the rotating direction in said rotary blade, protrusion walls provided at the positions on the outer peripheral surface of said rotary blade at the initial time of normal or reverse rotation of said rotational shaft, two chambers passed adjacent to the projection partitioned in the casing by said protrusion, and a pair of passages having check valves for opening and closing reversely the passages thereof and high viscous fluid flowrate regulating valves and provided in the protrusion to communicate the adjacent two chambers.

2. A damper for a foldable bed and the like comprising a rotary blade having an outer diameter of a long axis direction smaller than the inner diameter of a casing of a cylindrical shape having a protrusion on the portion of the inner peripheral wall surface thereof and arranged in the casing to be normally or reversely rotatable at a predetermined angle integrally with a rotational shaft rotatable together with the bed or the like, high viscous fluid provided in said casing being provided between said casing and the rotary blade, a pair of passages respective having check valves to be reversely opened or closed by the normal or reverse rotation of said rotary blade and passed to be formed in the rotating direction in said rotary blade, protrusion walls provided at the positions on the outer peripheral surface of said rotary blade at the initial time of normal or reverse rotation of said rotational shaft, an upper passage passed to communicate to chambers partitioned adjacent to said protrusion in said casing, a lower passage provided to communicate with said upper passage, both ends thereof and on the way thereto by connection holes, regulating threaded shafts passed through both ends of said upper passage and said lower passage, movable valves arranged movably to said connection hole side by the high viscous fluid in said lower passage to be inserted thereto, a pair of control valves supported at one ends thereof to the regulating screws engaged into a cover plate of said casing and provided with springs energized in a direction for resisting against the normal or reverse flow of the high viscous fluid to said movable valves, and a regulating valve for converting the flowing direction of the high viscous fluid to close the downstream side of the high viscous fluid in said upper passage at the time of normal or reverse rotation said rotary blade.