Rotary damper and automobile part comprising it and auxiliary mechanism of rotary operation

It is an object of the present invention to provide a rotary damper capable of automatically adjusting an exhibited braking force in correspondence with variation in load.A fluid chamber 2 into which viscous fluid is charged is formed in a casing 1. A vane 3 is disposed in the fluid chamber 2. The vane 3 is formed with a fluid passage 5, and is provided with a valve 6. The valve 6 automatically varies a flow rate of the viscous fluid passing through the fluid passage 5 in correspondence with variation in load. With this structure, it is possible to automatically adjust the exhibited braking force in correspondence with variation in load caused by variation in rotational motion of a subject to be controlled, and to reduce variation in rotation speed of the subject to be controlled to an extremely small value.

TECHNICAL FIELD

The present invention relates to a rotary damper, and more particularly, to a rotary damper capable of automatically adjusting a braking force exhibited in correspondence with change in load. The invention also relates to an auto part having the rotary damper, and a rotational motion assistant mechanism.

BACKGROUND ART

Conventionally, there is a known rotary damper which gives a predetermined braking force to a subject to be controlled which is rotated, thereby moderating its rotational motion.

The rotary damper includes a vane disposed in a fluid chamber in which viscous fluid is charged. The rotary damper generates a resistance against the viscous fluid by rocking the vane. There are a one-way rotary damper in which a check valve is provided so that the braking force can be exhibited only when the vane rocks in one direction (e.g., see the following patent documents 1 and 2), and a two-way rotary damper in which no check valve is provided so that the braking force can be exhibited irrespective of the rocking direction of the vane.

In this kind of rotary damper, the vane rocks and viscous fluid is pressed, and a resistance is generated when the viscous fluid moves through a small gap between the vane and a casing, and the resistance moderates the rotational motion of the subject to be controlled.

Therefore, the magnitude of the braking force exhibited by the rotary damper can be changed by changing a size of a gap or the like through which the viscous fluid passes when the viscous fluid moves. That is, if the gap is increased in size, the resistance of the viscous fluid is reduced and thus, the braking force can be reduced. If the gap is reduced in size on the contrary, the resistance of the viscous fluid is increased and thus, the braking force can be increased.

In the conventional rotary damper, the size of the gap through which the viscous fluid passes when the viscous fluid moves is usually constant. Thus, the exhibited braking force is also constant.

In a rotary damper in which the exhibited braking force is constant, when a load is small, the braking force becomes large relatively and when the load is great, the braking force becomes small relatively. Therefore, when the load is varied, the rotation speed of the subject to be controlled is largely varied.

Therefore, if such a rotary damper is applied to the subject to be controlled which has an accommodating section for accommodating an article such as an inner lid of a console box of an automobile or a glove box disposed in an opening formed in an instrument panel of an automobile, and in which the accommodating section is turned, a rotational moment of the subject to be controlled is small when no article is accommodated, and since a load applied to the rotary damper is small, the rotational motion of the subject to be controlled becomes extremely slow. On the contrary, when an article is accommodated, the rotational moment of the subject to be controlled is great and the load applied to the rotary damper becomes great and thus, the rotational motion of the subject to be controlled adversely becomes fast.

There is also a known rotary damper in which a size of a gap or the like through which viscous fluid passes when the viscous fluid moves is changed by operating the gap from outside, and the exhibited braking force can be adjusted (e.g., see the following patent documents 3 and 4).

In such a rotary damper, however, although the braking force can be adjusted, this adjustment is carried out based on a premise that a load to be applied to the rotary damper is constant after the adjustment. Thus, even if the braking force exhibited in accordance with a subject to be controlled is adjusted at initial stage of installation of the rotary damper, if a weight of the subject to be controlled is changed thereafter and a load to be applied to the rotary damper is changed, it is not possible to rotate the subject to be controlled at desired rotation speed unless the braking force is again adjusted.

Further, such a rotary damper must be operated from outside to adjust the braking force. Thus, if the rotational moment of the subject to be controlled is frequently changed and its changing amount is not constant like the inner lid of the console box or the glove box, this rotary damper is not suitable. That is, if the rotary damper is applied to such a subject to be controlled, whenever the rotational moment is changed as an article is loaded and unloaded, the braking force of the rotary damper must be adjusted again by predicting the changing amount of the rotational moment and operating the rotary damper from outside. Thus, it is difficult to appropriately adjust the braking force, and its operation is extremely troublesome and inconvenient.

In the conventional one-way rotary damper, a valve which realizes the one way rotary damper is formed as an independent member and then, the valve is assembled as one constituent part of the rotary damper. Thus, the number of parts is increased, a procedure for assembling the valve is necessary, and this increases the producing cost.

The rotary damper can moderate the rotational motion of the subject to be controlled by its shock absorbing effect. Therefore, when the rotary damper is applied to a reclining seat of an automobile, it is possible to moderate the forward rotational motion of a seat back against a biasing force of a spring member of a reclining mechanism which biases the seat back of the seat forward (see the following patent document 5 for example).

In the conventional rotary damper, however, the braking force can not be adjusted in accordance with the change in load. Therefore, in a reclining seat from which a head rest can be detached, the rotational moment of the seat back is changed between a case in which the head rest is attached and a case in which the head rest is detached. Thus, the rotation speed of the seat back is largely changed depending upon presence and absence of the head rest.

As other auto part, it is proposed to use the rotary damper also for an arm rest (see the following patent document 6 for example). However, in the arm rest having an accommodating section for articles, the rotational moment of the arm rest is changed depending upon a case in which the article is accommodated and a case in which no article is accommodated. Thus, in a rotary damper which can not adjust the braking force in accordance with the change in load, the rotational moment of the arm rest is changed, and its rotation speed is largely changed.

As a rotational motion assistant mechanism having a spring member which biases a subject to be controlled in one direction, there is a known mechanism which can adjust a biasing force of a spring member applied to the subject to be controlled by utilizing a fact that a stress of the spring member is changed by changing a position of a fulcrum of the spring member (see the following patent document 7 for example).

According to such a rotational motion assistant mechanism, however, since the biasing force of the spring member applied to the subject to be controlled is adjusted, a user must somehow operate the mechanism to change the position of the fulcrum of the spring member, and such an operation is troublesome and inconvenient.

The present invention has been accomplished in view of the above-described circumstances, and it is an object of the invention to provide a rotary damper capable of automatically adjusting a braking force exhibited in correspondence with change in load. It is another object of the invention to provide an auto part in which variation in rotation speed is small even if the rotational moment is changed. It is another object of the invention to provide a rotational motion assistant mechanism capable of automatically adjusting a biasing force of a spring member applied to a subject to be controlled in correspondence with change in rotation moment of the subject to be controlled.

DISCLOSURE OF THE INVENTION

To solve the above problems, the present invention provides the following rotary damper, auto part and rotational motion assistant mechanism.

In the drawings, a symbol1represents a casing, a symbol2represents a fluid chamber, a symbol3represents vane, a symbol4represents a partition wall, a symbol5represents a fluid passage, a symbol6represents a valve and a symbol7represents a rotor.

BEST MODE FOR CARRYING OUT THE INVENTION

A rotary damper according to the present invention will be explained in detail based on embodiments illustrated in the drawings, but it should be noted that the scope of the invention is not limited by the embodiments.

FIGS. 1 to 3show an internal structure of a rotary damper D1according to the embodiment 1. As shown inFIGS. 1 to 3, a casing1of the rotary damper D1comprises a cylindrical portion1bwhose one end is opened and other end is closed with a bottom wall1a,and a closing portion1cwhich closes an opening of the cylindrical portion1b.An outer peripheral surface of the cylindrical portion1bis formed with a groove1d.The groove1dcan support one end of a spring member which biases a subject to be controlled in one direction. The subject to be controlled rotates. The cylindrical portion1bis provided with a partition wall4which projects from an inner peripheral surface of the cylindrical portion1bin its axial direction. A tip end surface of the partition wall4is curved such that an outer peripheral surface of the rotor7slides on the tip end surface.

The rotor7is provided in the casing1. That is, the rotor7is provided in the casing1along an axis of the casing1. With this structure, a space partitioned by the partition wall4is formed between the rotor7and the casing1. This space serves as a fluid chamber2. Viscous fluid such as silicon oil is charged into the fluid chamber2.

Here, the rotor7includes a hollow portion7aformed such as to penetrate the rotor7along its axis. A support shaft which serves as a rotation center of the subject to be controlled is inserted into the hollow portion7a.By forming the hollow portion7ain the rotor7in this manner, the rotor7can directly be connected to the support shaft. Therefore, the installation space of the rotary damper D1can be reduced.

The vane3is integrally formed on the rotor7such as to project from the outer peripheral surface of the rotor7toward an inner peripheral surface of the cylindrical portion1b.The vane3has such a length along its axial direction that when the rotor7rotates in the casing1, one end surface of the vane3slides on the closing portion1cand the other end surface slides on the bottom wall1aof the cylindrical portion1b.The vane3has such a radial length that the tip end surface slides on the inner peripheral surface of the cylindrical portion1b.This vane3is disposed in the fluid chamber2. With this structure, the one fluid chamber2is partitioned into two chambers (“first chamber2a” and “second chamber2b”, hereinafter).

The fluid passage5is formed in the vane3along a direction substantially in parallel to the axis of the rotor7such that one of the openings of the fluid passage5is in communication with the first chamber2aand the other opening is in communication with the second chamber2b(seeFIG. 3). If the fluid passage5is provided in the direction substantially in parallel to the axis of the rotor7in this manner, the shape of a mold for forming the rotor7can be simplified and thus, the producing cost of the mold can be suppressed.

The valve6automatically adjusts a flow rate of the viscous fluid passing through the fluid passage5in accordance with variation in load. That is, the valve6reduces the flow rate of the viscous fluid passing through the fluid passage5as the load is increased, and increases the flow rate of the viscous fluid as the load is reduced without operating from outside. In this embodiment, in order to achieve this function with a simple structure, the following valve6is employed.

That is, as shown inFIGS. 3 and 4, the valve6is a leaf spring comprising a to-be supported portion6csupported by the vane3, and a flow rate-adjusting portion6d.A pressure-receiving surface is formed on one surface of the flow rate-adjusting portion6d,and if the pressure-receiving surface receives a pressure of the viscous fluid, the pressure-receiving surface is deformed to adjust the flow rate of the viscous fluid passing through the fluid passage5.

The to-be supported portion6cis fixed to the vane3. The flow rate-adjusting portion6dis formed at its one surface with two inclined surfaces6aand6bwhose inclining angles are different from each other. The to-be supported portion6cis provided such that when no load is applied, the fluid passage5is not closed (seeFIG. 3). In this manner, the flow rate-adjusting portion6dis formed at its one surface with the pressure-receiving surface comprising the two inclined surfaces6aand6bhaving the different inclining angles. With this structure, the surface of the flow rate-adjusting portion6dreceiving the pressure of the viscous fluid is formed with the bent portion. Therefore, it is possible to cover a wider range of variation of the load as compared with a flow rate-adjusting portion having only one inclined surface.

The rotary damper D1having the above-described structure functions as follows. That is, if the rotor7connected to the subject to be controlled through the support shaft is rotated in the counterclockwise direction in the casing1as the subject to be controlled is rotated inFIG. 1, the vane3pushes the viscous fluid in the second chamber2b.With this, the viscous fluid in the second chamber2bflows into the fluid passage5. As shown inFIGS. 3 and 5(a), the valve6located on the one of the openings of the fluid passage5is provided such that the flow rate-adjusting portion6ddoes not close the fluid passage5. Therefore, the viscous fluid which flowed into the fluid passage5from the second chamber2bpasses through the fluid passage5and flows into the first chamber2awithout being prevented from moving by the valve6almost at all. Thus, the resistance of the viscous fluid is extremely small. Therefore, the rotary damper D1does not exhibit a braking force which affects the rotational motion of the subject to be controlled.

If the rotor7rotates in the clockwise direction in the casing1inFIG. 1as the subject to be controlled rotates in the opposite direction on the contrary, the vane3pushes the viscous fluid in the first chamber2a.With this, the pressure-receiving surfaces6aand6bformed on the flow rate-adjusting portion6dof the valve6receive the pressure of the viscous fluid.

At that time, when the rotational moment of the subject to be controlled is small and the load applied to the rotary damper D1is small, a force of the vane3pushing the viscous fluid in the first chamber2ais small and a pressure of the viscous fluid generated by this is also small. Therefore, the flow rate-adjusting portion6dof the valve6is only slightly deformed in a direction closing the fluid passage5as compared with a case in which the flow rate-adjusting portion6ddoes not receive the pressure of the viscous fluid (seeFIG. 5(a)).

On the other hand, when the rotational moment of the subject to be controlled is great and the load applied to the rotary damper D1is great, the force of the vane3pushing the viscous fluid in the first chamber2ais also great, and the pressure of the viscous fluid generated by this is also high. Therefore, the flow rate-adjusting portion6dof the valve6is deformed such as to close a portion of the opening of the fluid passage5closer to the first chamber2aby a portion of the flow rate-adjusting portion6dhaving one (6a) of the two inclined surfaces6aand6bhaving the smaller inclining angle as shown inFIG. 5(b).

When a load equal to or greater than a predetermined value is applied to the rotary damper D1, not only the portion of the flow rate-adjusting portion6dof the valve6having the inclined surface6abut also a portion of the flow rate-adjusting portion6dhaving the inclined surface6bhaving the larger inclining angle are largely deformed, and the flow rate-adjusting portion6dcompletely closes the fluid passage5as shown inFIG. 5(c).

By employing, in the rotary damper D1, the valve6having the flow rate-adjusting portion6dwhose deforming degree is changed in accordance with variation in load, a gap between the flow rate-adjusting portion6dof the valve6and the opening of the fluid passage5closer to the first chamber2acan be made small and the opening can be closed gradually as the load is increased. Therefore, it is possible to limit the flow rate of the viscous fluid moving from the first chamber2ato the second chamber2bthrough the fluid passage5such that the flow rate is gradually reduced.

Thus, according to the rotary damper D1, it is possible to automatically adjust the magnitude of the braking force which is exhibited in accordance with variation in load such that when the load is small, the braking force to be exhibited is small, and when the load is great, the braking force to be exhibited becomes great without operating the rotary damper from outside. As a result, according to the rotary damper D1, the variation in rotation speed can be reduced to an extremely small value even if the rotational moment of the subject to be controlled is varied.

When the flow rate-adjusting portion6dof the valve6completely closes the fluid passage5, the viscous fluid can not move from the first chamber2ato the second chamber2bthrough the fluid passage5, and the viscous fluid can only move between the chambers2aand2bthrough a slight gap formed between the casing1and the vane3. Thus, the rotary damper D1exhibits greater braking force.

In order to confirm the characteristics of the rotary dampers D1of the embodiment, experiments for comparing the rotary damper D1of the embodiment with a comparative example were carried out. The rotary damper of the comparative example had a normal check valve as a valve which limited the movement of viscous fluid, i.e., a valve which prevented the viscous fluid from flowing reversely and which allowed the viscous fluid to flow only in one direction. Other structures of the rotary damper of the comparative example are the same as those of the rotary damper D1of the embodiment.

In the experiments, a plate body whose one end was pivotally supported and other end was free was used as the subject to be controlled, and a support shaft which was a rotation center of the subject to be controlled was connected to the rotary damper D1of the embodiment. The comparative example had the same condition. Operation time required from the instant when the free end of the subject to be controlled fell from an angle position of 60° to the instant when the free end reached an angle position of 0° was measured. The rotational motion of the subject to be controlled was changed by adding a weight having different weight to the subject to be controlled. Table 1 shows a result of the experiments, and the average operation time is shown inFIG. 6as a graph.

From the results shown in Table 1 andFIG. 6, it can be found that if the rotational moment of the subject to be controlled controlled by the rotary damper of the comparative example is changed, its operation time is also changed largely. On the other hand, in the case of the subject to be controlled controlled by the rotary damper D1of the present embodiment, it can be found that even if the rotational moment is changed, the variation in operation time thereof is extremely small. That is, differences of the average operation time when the rotational moment is 0.5N·m and 3.0N·m are compared, the difference of the operation time of the subject to be controlled controlled by the rotary damper D1of the present embodiment is 6.01 seconds and the variation is small, but the difference of the operation time of the subject to be controlled controlled by the rotary damper of the comparative example is 21.95 seconds and the variation is extremely large. Further, differences of the average operation time when the rotational moment is 1.0N·m and 3.0N·m are compared with each other, the difference of the operation time of the subject to be controlled controlled by the rotary damper D1of the present embodiment is only 3.49 seconds and the variation is extremely small, but the difference of the operation time of the subject to be controlled controlled by the rotary damper of the comparative example is 13.73 seconds and the variation is large. From the results, it was confirmed that according to the rotary damper D1of the present embodiment, even if the rotational moment of the subject to be controlled was changed, the braking force exhibited in correspondence with the variation in load was automatically adjusted, and the variation of the rotation speed of the subject to be controlled could be reduced to an extremely small value.

In a rotary damper D2of this embodiment, as shown inFIGS. 7,9and11, the fluid passage5comprises large hole portions5awhich pass through the fluid passage5in the thickness direction of the vane3and which are in communication with each other, and a small hole portion5bwhich is smaller than the large hole portion5ain diameter. As shown inFIG. 10, the valve6comprises a leaf spring having to-be supported portions6eand6fand a flow rate-adjusting portion6g.

As shown inFIG. 10, in the valve6, in order to secure a passage for the viscous fluid, a width of a central portion of the flow rate-adjusting portion6glocated between the to-be supported portions (opposite ends)6eand6fis smaller than widths of the to-be supported portions (opposite ends)6eand6f.The to-be supported portions (opposite ends)6eand6fof the valve6are folded back into substantially U-shape as viewed from side so that the inner surface of the casing1(inner surfaces of the bottom wall1aand inner surface of the closing portion1c) is not damaged by the to-be supported portions (opposite ends)6eand6f.The flow rate-adjusting portion6dis bent such that one surface thereof projects.

As shown inFIGS. 7,9and11, the valve6is located on a boundary portion between the large hole portion5aand the small hole portion5bconstituting the fluid passage5, and is disposed in a groove5cformed along a direction which is substantially perpendicular to the thickness direction of the vane3.

Like the embodiment 1, this valve6is provided such that when no load is applied, the fluid passage6is not closed by the flow rate-adjusting portion6g.That is, when no load is applied to the rotary damper D2, as shown inFIG. 11(a), the to-be supported portions (opposite ends)6eand6fof the valve6abut against the vane3in the groove5c,and even when they are supported by the vane3, the flow rate-adjusting portion6gmaintains such a shape that the flow rate-adjusting portion6gis bent such that its one surface is bent. Therefore, a gap through which the viscous fluid can pass is formed between the flow rate-adjusting portion6gand an opening of the small hole portion5bcloser to the large hole portion5awhich constitutes the fluid passage5(simply “opening of the small hole portion5b”, hereinafter).

In the rotary damper D2having the above-described structure, if the rotor7is rotated in the counterclockwise direction inFIG. 7in the casing1, the vane3pushes the viscous fluid in the first chamber2a.With this the flow rate-adjusting portion6gof the valve6receives the pressure of the viscous fluid flowing into the large hole portion5aof the fluid passage5, and the flow rate-adjusting portion6gis deformed in a direction closing the opening of the small hole portion5b.

At that time, when the load applied to the rotary damper D2is small, a force of the vane3pressing the viscous fluid in the first chamber2ais also small and the pressure of the viscous fluid generated by this is also small. Therefore, the flow rate-adjusting portion6gof the valve6is only deformed slightly in a direction closing the opening of the small hole portion5bas compared with a case in which the flow rate-adjusting portion6gdoes not receive the pressure of the viscous fluid (seeFIG. 11(a)).

On the other hand, when the load applied to the rotary damper D2is large, the force of the vane3pressing the viscous fluid in the first chamber2ais also strong and the pressure of the viscous fluid generated by this is also great. Therefore, the flow rate-adjusting portion6gof the valve6is largely deformed in the direction closing the opening of the small hole portion5bas compared with a case in which the load is small.

When a load equal to or greater than a predetermined value is applied, the flow rate-adjusting portion6gof the valve6is more largely deformed and completely closes the opening of the small hole portion5bas shown inFIG. 11(b).

According to the rotary damper D2, like the embodiment 1, the valve6having the flow rate-adjusting portion6gwhose deforming degree is varied in accordance with the variation in load is employed. Therefore, as the load becomes greater, the gap between the flow rate-adjusting portion6gof the valve6and the opening of the small hole portion5bconstituting the fluid passage5becomes smaller and the opening can be closed gradually. Thus, it is possible to limit the flow rate of the viscous fluid which moves from the first chamber2ato the second chamber2bthrough the fluid passage5such that the flow rate is gradually reduced.

Thus, according to the rotary damper D2, the magnitude of the braking force exhibited in accordance with the variation in load can automatically be adjusted without operating the rotary damper from outside such that when the load is small, the braking force to be exhibited is small, and when the load is great, the braking force to be exhibited becomes great. As a result, like the embodiment 1, even if the rotational moment of the subject to be controlled is varied, the variation in rotation speed can be reduced to an extremely small value.

When the flow rate-adjusting portion6gof the valve6completely closes the small hole portion5bof the fluid passage5, the viscous fluid can not pass through the fluid passage5, and the viscous fluid can move between the first chamber2aand the second chamber2bonly through the small gap formed between the casing1and the vane3. Thus, the rotary damper D2exhibits greater braking force.

When the rotor7is rotated in the clockwise direction inFIG. 7in the casing1on the contrary, the vane3pushes the viscous fluid in the second chamber2b.With this, the viscous fluid in the second chamber2bflows into the small hole portion5bof the fluid passage5. At that time, since the flow rate-adjusting portion6gof the valve6is provided such that it does not close the opening of the small hole portion5bas shown inFIG. 11(a), the viscous fluid which flowed into the small hole portion5bflows into the large hole portion5aand into the first chamber2awithout being prevented from moving by the valve6almost at all. Thus, the resistance of the viscous fluid is extremely small. Therefore, the rotary damper D2does not exhibit a braking force which can affect the rotational motion of the subject to be controlled.

FIGS. 12 to 15show an internal structure of a rotary damper D3of this embodiment. As shown in these drawings, the casing1of the rotary damper D3comprises a cylindrical portion1ehaving a substantially circular cross section, and first and second closing portions1fand1gwhich close opposite ends of the cylindrical portion1e.The first closing portion1fwhich closes one end of the cylindrical portion1eis formed at its inner surface with a recess having a substantially arc cross section. A hard member12cwhich will be described later is disposed in the recess. By disposing the hard member12cin the recess, a surface having a projection against which a later-described rolling member12bis formed (seeFIGS. 14 and 17). Instead of forming the recess in the inner surface of the first closing portion1f,this portion may be protruded and the inner surface itself of the first closing portion1fmay be formed with the projection. The first and second closing portions1fand1ghave shaft insertion holes1hand1ithrough which the rotor7is inserted. The rotor7functions as a rotation shaft. The first and second closing portions1fand1gare mounted by swaging the cylindrical portion1e.

The opposite ends of the rotor7are supported by the shaft insertion holes1hand1irespectively formed in the first and second closing portions1fand1gso that the rotor7is provided along an axis of the casing1. The rotor7is hollow, and an inner shaft13is disposed in the hollow portion. The inner shaft13has such a shape that the inner shaft13engages with the rotor7and can rotate together with the rotor7, and the inner shaft13is cut at its intermediate portion, and a coil spring14is disposed in the cut portion. With this structure, the inner shaft13can expand and shrink using the resilience of the coil spring14and thus, the inner shaft13can easily be mounted on the subject to be controlled.

When the rotary damper D3of this embodiment is applied as a double lid type opening/closing supporting mechanism comprising an outer lid and an inner lid, a base end of the outer lid is rotatably connected to the inner shaft13, a base end of the inner lid is engaged and mounted such that the inner shaft13is rotated by rotating the inner lid. With this structure, the outer lid and the inner lid can opened and closed independently. When the inner shaft13is rotatably provided in the hollow portion of the rotor7unlike this embodiment, the base end of the inner lid is connected to the rotor7, and the base end of the outer lid is connected to the inner shaft13. With this structure, the outer lid and the inner lid can opened and closed independently.

As shown inFIG. 15, the partition walls4are provided such as to project from the inner peripheral surface of the cylindrical portion1ewhich constitutes the casing1and such as to be opposed to each other. Each of tip end surfaces of the partition walls4has a substantially arc cross section so that the tip end surface slides on the outer peripheral surface of the rotor7.

As shown inFIG. 15, the vane3projects from the rotor7and is disposed such as to partition the fluid chamber2into the first chamber2aand the second chamber2bby means of the partition walls4. In this embodiment, two vanes3are disposed such as to be opposed to each other with the rotor7interposed therebetween such that each of the two fluid chambers2formed in the casing1are partitioned into the first chamber2aand the second chamber2bby the two partition walls4. As shown inFIG. 12, each vane3is formed with the fluid passage5which passes through the vane3in its thickness direction.

Viscous fluid such as silicon oil is charged into the fluid chamber2. A seal member such as an O-ring is disposed on a predetermined position in the casing1to prevent the viscous fluid from leaking outside.

The valve6changes the flow rate of the viscous fluid moving from the first chamber2ato the second chamber2bthrough the fluid passage5in accordance with variation in load. That is, as the load becomes greater, the valve6reduces the flow rate of the viscous fluid passing through the fluid passage5, and as the load becomes smaller, the valve6increases the flow rate. A structure of the valve6is not limited only if the valve6can exhibit this function. In order to achieve this function with a simple structure, the following structure is employed for the valve6.

That is, as shown inFIGS. 12,15and16, the valve6comprises a leaf spring having the to-be supported portion6cand the flow rate-adjusting portion6d.The to-be supported portion6clocated at a substantially central portion of the valve6is fixed to the vane3using a push nut15. The flow rate-adjusting portion6dis formed into such a shape that it is inclined from the to-be supported portion6cso that the flow rate-adjusting portion6ddoes not close the fluid passage5when no load is applied.

As a preferred valve6, as shown inFIG. 16(a), the flow rate-adjusting portion6dis formed at its one surface with pressure-receiving surfaces comprising two or more inclined surfaces6aand6bhaving different inclining angles. With this structure, the surface of the valve6which receives the pressure of the viscous fluid is formed with the bent portion and thus, it is possible to cover a wider range of variation of the load as compared with a valve having only one inclined surface.

The rotary damper D3of this embodiment further comprises a click mechanism12. A structure of the click mechanism12is not limited only if the click mechanism12has a function for stopping the rotation of the rotor7at a predetermined rotation angle. For example, it is possible to employ a structure in which a pair of cam members are disposed such that their cam surfaces push against each other, one of the cam surfaces relatively slides on the other cam surface. If this structure using such cam members is employed, however, the cam member itself is expensive, the rotor7can not rotate smoothly due to deviated wear of the cam surface and thus, a click mechanism12having the following structure is employed in this embodiment.

That is, as shown inFIG. 12, the click mechanism12of this embodiment comprises a spring member12adisposed in the casing1, and a rolling member12b.The rolling member12bis biased by the spring member12aand brought into abutment against a surface having a projection formed in the casing1, and if the rotor7rotates, the rolling member12brolls along the abutment surface. In this embodiment, the projection constituting the surface (abutment surface) against which the rolling member12babuts comprises a hard member12cdisposed in the recess formed in the inner surface of the first closing portion1fand having predetermined hardness.

The spring member12acomprises a coil spring. In the casing1, one end of the spring member12ais integrally formed on the spring-receiving member12d,and the other end of the spring member12ais integrally formed with the rotor7. The one and the other ends of the spring member12aare supported by end walls7dof the cylindrical portion7chaving outer diameters which are substantially equal to an inner diameter of the cylindrical portion1ewhich constitutes the casing1. The spring-receiving member12dcomprises a disk which is formed at its substantially central portion with a hole12einto which the rotor7is inserted. The spring-receiving member12dis provided in the cylindrical portion7csuch that the spring-receiving member12dcan move in the axial direction along the rotor7(seeFIGS. 12,13and17).

The rolling member12bcomprises a steel ball. The rolling member12bis provided between the spring-receiving member12dand the first closing portion if. If the rolling member12bis biased by the spring member12athrough the spring-receiving member12d,the rolling member12babuts against a surface having the projection provided in the casing1, i.e., a surface comprising an inner surface of the first closing portion if and an outer peripheral surface of the hard member12cin this embodiment. Although the steel ball is employed as the rolling member12bin this embodiment, the rolling member12bis not limited to this only if the rolling member12bhas predetermined hardness and is formed into a shape capable of rolling.

The hard members12ccomprise parallel pins and rotatably disposed in the recesses formed in the first closing portion1f.Each the hard member12cis not limited if it has the predetermined hardness and is formed into a shape capable of forming a projection on a flat surface such as the inner surface of the first closing portion1f.For example, steel balls may be employed as the hard members12cinstead of the parallel pins. Steel balls and parallel pins subjected to thermal treatment and having predetermined hardness are commercially available, and they are less expensive than producing costs or prices of parts of the cam members. Therefore, if such commercial parts are used as the rolling member12bor hard member12c,the producing cost can largely be reduced.

When the hard member12cis not disposed, it is necessary to form a projection of the first closing portion if itself and to carry out the thermal treatment for the first closing portion1f.In this case also, it is possible to reduce the producing cost as compared with a case in which the pair of cam members constituting the mutually sliding cam surfaces must be subjected to the thermal treatment.

According to the click mechanism12of this embodiment, since the projection in which the deviated wear is most prone to be generated comprises the hard member12c,there are merits that this portion is less prone to be worn and the first closing portion1fforming the abutment surface of the rolling member12bneed not be subjected to the thermal treatment. Since the hard member12cis rotatably provided, the hard member12crotates when the rolling member12bcomes into contact with the hard member12c,the friction generated at that time can be reduced.

The rotary damper D3having the above-described structure is used in the following manner. That is, when the rotary damper D3is used as the double lid type opening/closing supporting mechanism comprising the outer lid and the inner lid, the casing1of the rotary damper D3is fixed to the stationary portion, and the base end of the frame constituting the inner lid and the base end of the frame constituting the outer lid are connected to the inner shaft13.

Here, if the inner lid can accommodate an article, the weight of the inner lid is largely changed between a case in which the inner lid sufficiently accommodates the article and a case in which the inner lid accommodates no article. When the inner lid is closed together with the outer lid, the weight of the outer lid is added to the weight of the inner lid. A load applied to the rotary damper D3is largely changed between a case in which the inner lid accommodates no article and only the inner lid is closed, and a case in which the inner lid sufficiently accommodates the articles and the inner lid is closed together with the outer lid.

In this rotary damper D3, as the inner lid rotates in its closing direction, the rotor7rotates in the counterclockwise direction inFIG. 15. With this configuration, the vane3pushes the viscous fluid in the first chamber2a.With this, the flow rate-adjusting portion6dof the valve6receives the pressure of the viscous fluid and is deformed in the direction closing the fluid passage5. When a load applied to the rotary damper D3is small, for example when no article is accommodated in the inner lid and only the inner lid is to be closed, a force of the vane3pushing the viscous fluid in the first chamber2ais weak and the pressure of the viscous fluid is also small. Therefore, as shown inFIG. 16(b), the flow rate-adjusting portion6dof the valve6is only slightly deformed in a direction closing the fluid passage5as compared with a case in which the flow rate-adjusting portion6ddoes not receive the pressure of the viscous fluid (seeFIG. 16(a)).

On the other hand, when the load applied to the rotary damper D3is large, for example, the inner lid sufficiently accommodates the articles and the inner lid is closed together with the outer lid, a force of the vane3pushing the viscous fluid in the first chamber2ais strong and the pressure of the viscous fluid is also great. Therefore, as shown inFIG. 16(c), the flow rate-adjusting portion6dof the valve6is largely deformed such as to close a portion of the opening of the fluid passage5close to the first chamber2aby its portion having one (6a) of the two inclined surfaces6aand6bhaving the smaller inclining angle.

When a load equal to or greater than the predetermined value is applied, not only the portion the flow rate-adjusting portion6dof the valve6having the inclined surface6awhose inclining angle is small but also its portion having the inclined surface6bwhose inclining angle is greater than that of the inclined surface6ais largely deformed, thereby completely closing the fluid passage5as shown inFIG. 16(d).

As described above, the rotary damper D3employs the valve6having the flow rate-adjusting portion6dwhose deforming degree is changed in accordance with the variation in load like the embodiment 1. Thus, as the load is increased, the gap between the flow rate-adjusting portion6dof the valve6and the opening of the fluid passage5is reduced, and the opening can be closed gradually. Therefore, the flow rate of the viscous fluid moving from the first chamber2ato the second chamber2bthrough the fluid passage5can be limited such that the flow rate is gradually reduced.

Therefore, according to the rotary damper D3, it is possible to automatically adjust the magnitude of the braking force exhibited in correspondence with the variation in load without operating the rotary damper D3from outside such that the exhibited braking force becomes small when the load is small and the exhibited braking force when the load is great becomes great. As a result, even if the rotational moment of the inner lid as the subject to be controlled is changed, the variation of the rotation speed can be reduced to an extremely small value like the embodiment 1.

When the flow rate-adjusting portion6dof the valve6completely closes the fluid passage5, the viscous fluid can not pass through the fluid passage5, and the viscous fluid can move between the first chamber2aand the second chamber2bonly through the small gap formed between the casing1and the vane3. Thus, the rotary damper D3exhibits greater braking force.

On the other hand, when the inner lid is opened from its closed state, as the inner lid rotates in its opening direction, the rotor7rotates in the clockwise direction inFIG. 15so that the vane3pushes the viscous fluid in the second chamber2b.At that time, the flow rate-adjusting portion6dof the valve6brings the fluid passage5into its fully opening state as shown inFIG. 16(a). Thus, a large amount of viscous fluid in the second chamber2bcan move into the first chamber2athrough the fluid passage5, the rotary damper D3does not exhibit the braking force, and the inner lid can smoothly be opened.

Since the rotary damper D3includes the click mechanism12, the inner lid can be independent in the fully opened position for example. That is, as the inner lid is opening from its fully closed position toward the fully opened position, the inner shaft13and the rotor7which engages with the inner shaft13rotate. With this, the rolling member12bbiased by the spring member12arolls along the inner surface of the first closing portion if as shown inFIG. 17(a).

When the inner lid reaches a position immediately before it fully opens, as shown inFIG. 17(b), the rolling member12bruns on the top of the hard member12cand immediately after that, i.e., when the inner lid reaches the fully opened position, as shown inFIG. 17(c), the rolling member12brolls down from the top of the hard member12calong the curved surface (outer peripheral surface) of the hard member12c,and reaches the inner surface of the first closing portion if. With this, the rotation of the inner shaft13and the rotor7is stopped, and the inner lid can be independent in the fully opened position. On the other hand, if an external force having a constant or higher value is applied to the inner lid in its fully opened state, the rolling member12brolls in the opposite direction, and the rolling member12bruns across the hard member12c. With this, the independent state of the inner lid is released.

According to the rotary damper D3of this embodiment, it is possible to automatically adjust the exhibited braking force in correspondence with variation in load, and to stop the rotor7at a predetermined rotation angle. Further, the above effect can be obtained with the simple structure and with a single body. Thus, it is possible to exhibit the damping function and clicking function for the subject to be controlled with only the single rotary damper D3.

As shown inFIGS. 18 and 19, a rotary damper D4of this embodiment is different from the rotary damper D3of the embodiment 3 in that one of two through holes formed in the single vane3is used as a valve hole for the valve6and the other through hole is used as a valve hole for a check valve11, and the check valve11is provided in addition to the valve6.

That is, in the embodiment 3, the one vane3is formed with the two fluid passages5, and both of them function as the valve holes for varying the flow rate of the viscous fluid moving from the first chamber2ato the second chamber2bin correspondence with variation of the load. Whereas, in the embodiment 4, as shown inFIGS. 18 and 19, one of the two through holes formed in the one vane3mainly functions as the valve hole (fluid passage5) for the valve6, and the other through hole functions as the valve hole11afor the check valve11.

Here, the check valve11may comprise a leaf spring or the like which is independent from a leaf spring constituting the valve6, but in order to reduce the number of parts, it is preferable that the valve6and the check valve11comprise one leaf spring as shown inFIG. 19(a).

The check valve11is provided such that it closes the valve hole11awhen no load is applied, and only when the viscous fluid moves from the second chamber2bto the first chamber2a,the check valve11receives the pressure of the viscous fluid and is deformed as shown inFIG. 19(b), and opens the valve hole11a.With this, when the viscous fluid moves from the second chamber2bto the first chamber2a,a large amount of viscous fluid can move through the two through holes, i.e., the fluid passage5and the valve hole11aand thus, it is possible to reduce the resistance of the viscous fluid generated at that time to an extremely small value.

A rotary damper D5of the embodiment 5 is different from the rotary damper D3of the embodiment 3 in that a spring member16which biases the rotor7which rotates in the non-braking force exhibiting direction is provided in the casing1instead of the click mechanism as shown inFIG. 20.

The spring member16comprises a coil spring. One end of the spring member16is supported by the first closing portion if and the other end is supported by the end wall7dof the cylindrical portion7c.The cylindrical portion7chas an outer diameter which is substantially the same as an inner diameter of the cylindrical portion1ewhich constitutes the casing1. The cylindrical portion7cis integrally formed with the rotor7.

The rotary damper D5has the spring member16. In the example of use explained in the embodiment 3, the spring member16is twisted, and energy accumulated in the spring member16is released when the inner lid is opened, and as the inner lid is opened, the rotor7which rotates in the non-braking force exhibiting direction is biased. Thus, the inner lid can be opened automatically or with small force.

FIGS. 21 to 23show an internal structure of a rotary damper D6of the embodiment 6. As shownFIGS. 21 to 23, the casing1of the rotary damper D6includes a cylindrical portion1mhaving a substantially circular cross section, a first closing portion in which is integrally formed on the cylindrical portion1mat one end of the cylindrical portion1m,and a second closing portion1omounted to the other end of the cylindrical portion1mby swaging. Opposite ends of the cylindrical portion1mare closed by the first and second closing portions1nand1o.The first and second closing portions1nand1oare provided at their substantially central portions with holes1pand1q.The holes1pand1qare provided at their peripheral edges with projections1rand1swhich are fitted into grooves7eand7fformed in the rotor7to support the rotor7.

The rotor7is provided at its substantially central portion with the hollow portion7a.A shaft which rotates together with the subject to be controlled is inserted into the hollow portion7a.The opposite end surfaces of the rotor7are formed with annular grooves7eand7f,respectively. The rotor7is supported such that the projections1pand1qof the first and second closing portions1nand1oare fitted into the grooves7eand7f,and the rotor7is rotatable relatively with the casing1.

The partition walls4partition a space formed around the rotor7in the casing1. More specifically, as shown inFIG. 21, the partition walls4are opposed such that they project from the inner peripheral surface of the cylindrical portion1mwhich constitutes the casing1to the axial direction, and each tip end surface of the partition wall4has substantially arc cross section such that the tip end subject slides on the outer peripheral surface of the rotor7.

By partitioning the space around the rotor7by the partition walls4as described above, the space formed in the casing1is the fluid chamber2, and viscous fluid such as silicon oil is charged into the fluid chamber2.

As shown inFIGS. 21 and 22, the vanes3are integrally formed on the rotor7such that the vanes3project from the outer peripheral surface of the rotor7toward the inner peripheral surface of the cylindrical portion1m. In this embodiment, the vanes3are provided at symmetric positions with respect to the rotor7. As shown inFIG. 22, each vane3is formed into a plate shape having such a size that as the rotor7rotates, a tip end surface3aof the vane3slides on the cylindrical portion1m,an upper end surface3bof the vane3slides on the second closing portion1o,and a lower end surface3cof the vane3slides on the first closing portion1n.Each vane3is formed with the fluid passage5which passes through the vane3in its thickness direction. The number of fluid passages5is not limited, and one vane3may be formed with a plurality of fluid passages5.

As shown inFIGS. 21,23and24, the valve6includes a surface (“opposed surface”, hereinafter)6mwhich is opposed to one side surface3dof the vane3at a constant distance from the one side surface3dof the vane3and which has an area capable of closing the fluid passage5, and a surface (“pressure-receiving surface”, hereinafter)6nwhich is located on the opposite side of the opposed surface6mand which receives the pressure of the viscous fluid as the vane3rocks. The valve6is integrally formed on the vane3such that a portion of the valve6other than a root6oprojecting from the one side surface3dof the vane3is not related to any portion of the vane3.

If the valve6has such resilience that if the valve6receives an external force, the valve6is deformed, and if the external force is released, the valve6is returned to its original shape. The magnitude of the external force which can deform the valve6is varied depending upon how a material, a size and a shape of the valve6are set. Especially, this largely depends on a width of the root6oof the valve6and a shape of the valve6near the root6o.The same can be said as to how much the valve6is deformed if it receives the external force.

For example, as shown inFIG. 25, the root6oof the valve6has substantially arc cross section and the vane3is formed at its portion near the root6owith a dent3e.With this structure, the valve6can be deformed such that the opposed surface6mof the valve6comes into intimate contact with the one side surface3dof the vane3and the fluid passage5is closed.

When no load is applied, since the opposed surface6mof the valve6is separated from the one side surface3dof the vane3at a constant distance, the fluid passage5is opened. On the other hand, if the predetermined or higher load is applied to the rotary damper D6, the pressure-receiving surface6nreceives the pressure of the viscous fluid generated at that time and the valve6is deformed, the opposed surface6mcomes into intimate contact with the one side surface3dof the vane3to close the fluid passage5. If the load applied to the rotary damper D6is released, the valve6is returned to its original shape by the resilience of the valve6, i.e., the valve6is returned to its state when no load is applied.

If the valve6is disposed closer to the one side surface3dof the vane3as shown inFIG. 21, the rotary damper D6becomes the one-way damper in which the rotary damper D6exhibits the braking force in one direction only when the vane3rocks in the one direction. On the other hand, the valves6are disposed on opposite sides of the vane3(not shown), the rotary damper D6becomes the two-way damper in which the rotary damper D6exhibits the braking force not only when the vane3rocks in the one direction but also when the vane3rocks in the opposite direction.

The rotary damper D6having the above-described structure is used such that the casing1is fixed to the stationary portion and the shaft which rotates together with the subject to be controlled is inserted into the hollow portion7aof the rotor7, and the rotor7is connected to the subject to be controlled through the shaft.

If the subject to be controlled is rotated in the one direction, the rotor7connected to the subject to be controlled is rotated in the clockwise direction inFIG. 21, and as the rotor7rotates, the vane3rocks in the clockwise direction like the rotor7. With this, the pressure-receiving surface6nof the valve6receives the pressure of the viscous fluid charged into the fluid chamber2.

At that time, if the load applied to the rotary damper D6is small, the pressure of the viscous fluid is also small and thus, even if the pressure-receiving surface6nreceives the pressure of the viscous fluid, the valve6is deformed only slightly, and only a portion of the fluid passage5is closed by the valve6. On the other hand, if the load applied to the rotary damper D6is great, the pressure of the viscous fluid is also great, and the valve6is deformed greater than that when the load is small, and more portion of the fluid passage5is closed by the valve6than that when the load is small. If the load applied to the rotary damper D6exceeds the predetermined value, the valve6is further deformed largely, the opposed surface6mcomes into intimate contact with the one side surface3dof the vane3, thereby completely closing the fluid passage5.

As described above, the deforming degree of the valve6is varied in accordance with the variation in load. Therefore, as the load is increased, the fluid passage5is automatically closed gradually, and it is possible to limit the flow rate of the viscous fluid moving through the fluid passage5such that the flow rate is gradually reduced. Here, the term “automatically” means “without operating the rotary damper from outside”. Thus, according to the rotary damper D6having such a valve6, it is possible to automatically adjust the magnitude of the braking force exhibited in accordance with variation in load such that when the load is small, the exhibited braking force becomes small, and when the load is great, the exhibited braking force becomes great. Thus, when the magnitude of the load is varied, it is possible to reduce the variation in rotation speed of the subject to be controlled to an extremely small value without operating the rotary damper D6.

InFIG. 21, when the vane3rocks in the counterclockwise direction, since the valve6opens the fluid passage5, the flow rate of the viscous fluid is not limited by the valve6and the viscous fluid can move through the fluid passage5. Therefore, the resistance of the viscous fluid becomes extremely small and thus, the subject to be controlled rotates without being affected by the braking force exhibited by the rotary damper D6.

Since the valve6employed in this embodiment is integrally formed on the vane3, the number of parts can be reduced as compared with the conventional rotary damper, and the assembling procedure of the valve6is unnecessary. Therefore, the producing cost can be reduced. When the check valve is formed as an independent member and then, the check valve is assembled as one constituent part of the rotary damper as in the conventional technique, there is an adverse possibility that an operator forgets about assembling the check valve in the producing line, but by integrally forming the valve6and the vane3together, such possibility can be eliminated completely.

As shown inFIG. 26, a rotary damper D7of the embodiment 7 is different from the rotary damper D6of the embodiment 6 in that the partition walls4are formed with the fluid passages5, and the valves6are integrally formed on the partition walls4.

As shown inFIG. 26, when the fluid passages5are formed in the partition walls4as in this embodiment, the valve6includes a surface (opposed surface)6mwhich is opposed to the one side surface4aof the partition wall4and which has an area capable of closing the fluid passage5, and a surface (pressure-receiving surface)6nwhich is located on the opposite side from the opposed surface6mand which receives the pressure of the viscous fluid as the vane3rocks. The valve6is integrally formed on the partition wall4such that a portion of the valve6other than the root6oprojecting from the one side surface4aof the partition wall4is not related to any portion of the partition wall4. The number of fluid passages5is not limited, and one partition wall4may be formed with a plurality of fluid passages5.

When no load is applied, since the valve6is in a state in which the opposed surface6mis separated from the one side surface4aof the partition wall4at the constant distance, when the valve6opens the fluid passage5and a predetermined or higher load is applied to the rotary damper D7, the pressure-receiving surface6nreceives the pressure of the viscous fluid generated at that time to deform the valve6, the opposed surface6mcomes into intimate contact with the one side surface4aof the partition wall4to close the fluid passage5.

If the valves6are disposed on the side of the one side surfaces4aof the partition walls4as shown inFIG. 26, the rotary damper D7becomes the one-way damper in which the rotary damper D7exhibits the braking force in one direction only when the vane3rocks in the one direction. On the other hand, the valves6are disposed on opposite sides of the partition wall4(not shown), the rotary damper D7becomes the two-way damper in which the rotary damper D7exhibits the braking force not only when the vane3rocks in the one direction but also when the vane3rocks in the opposite direction.

According to the rotary damper D7having the above-described structure also, the same effect as that of the rotary damper D6of the embodiment 6 can be obtained.

As shown inFIG. 27, a rotary damper D8according to the embodiment 8 is different from the rotary damper D6of the embodiment 6 in that each of the vanes3is divided into two pieces, and a valve6is disposed in a gap formed between the divided pieces. Similarly, a structure in which each of the partition walls4is divided into two pieces, and the valve6is disposed in the gap formed between the divided pieces may also be employed. Also when such a structure is employed, the valve6or the vane3is integrally formed on the partition wall4.

According to the rotary damper D8having the above-described structure, the valve6is deformed in accordance with the magnitude of the pressure of the viscous fluid, and the flow rate of the viscous fluid passing through the fluid passage5can automatically be varied in correspondence with the variation in load irrespective of the rocking direction of the vane3. Therefore, it is possible to reduce the variation of rotation speed of the subject to be controlled to an extremely small value irrespective of the rotation direction of the subject to be controlled without operating the rotary damper D8.

FIG. 28shows an internal structure of a rotary damper D9of the embodiment 9. As shown inFIG. 28, the rotary damper D9comprises a rotor7provided in the casing1, the fluid chambers2each partitioned by the partition wall4provided between the rotor7and the casing1and into which viscous fluid is charged, valve bodies18each projecting from the rotor7and capable of engaging with an engaging portion17disposed in the fluid chamber2with a play, fluid passages5each formed between the valve body18and the engaging portion17, and resilient members19each provided in the fluid passage5.

The partition walls4projecting from the inner peripheral surface of the casing1toward the axial direction are provided in the casing1. The tip end surface of each the partition wall4is formed into a curved surface so that the outer peripheral surface of the rotor7slides on the tip end surface. The rotor7includes the hollow portion7awhich is hollow along the axis of the rotor7. A shaft which serves as a rotation center of the subject to be controlled is inserted into the hollow portion7a.

The engaging portion17projects from the rotor7such that the engaging portion17projects from the outer peripheral surface of the rotor7toward the inner peripheral surface of the casing1. The engaging portion17is integrally formed on the rotor7such that the engaging portion17constitutes a portion of the rotor7, and a length of the engaging portion17along the axial direction is set such that when the rotor7is relatively rotated with respect to the casing1, one of the end surfaces of the engaging portion17slides on a closing portion (not shown) which closes the opening of the casing1and the other end surface slides on a bottom wall of the casing1. A length of the engaging portion17is set shorter than a distance from the inner peripheral surface of the casing1to the outer peripheral surface of the rotor7in the radial direction. The engaging portion17has bifurcated tip ends, and a gap between the bifurcated tip ends17aand17bforms an engaging groove17cinto which a projection18bof the valve body18engages.

The rotor7is rotatably provided in the casing1. With this structure, a space partitioned by the partition wall4is formed between the rotor7and the casing1. This space is the fluid chamber2, and viscous fluid such as silicon oil is charged into the fluid chamber2. The engaging portion17is disposed in the fluid chamber2.

As shown inFIG. 29, the valve body18is formed into a substantially T-shape comprising an arc portion18ahaving a substantially arc shape as viewed from above, and a projection18bprojecting from a substantially central portion of the arc portion18aopposed to the rotor7. Backflow grooves (first to third backflow grooves18cto18e) are formed in opposed surfaces of the arc portion18aand the engaging portion17with respect to the projection18band one side surface of the projection18b.The first to third backflow grooves18cto18eare formed at substantially central portions of the above-described surfaces. Instead of forming the first to third backflow grooves18cto18ein the opposed surface of the arc portion18awith respect to the projection18b,the first to third backflow grooves18cto18emay be formed in the tip ends17aand17bof the engaging portion17.

A length h of the valve body18in its axial direction is substantially the same as the length of the engaging portion17in its axial direction, and a width d of the arc portion18ais set wider so that the arc portion18acomes into contact with the tip ends17aand17bof the engaging portion17.

The valve body18having the above-described shape is provided in the fluid chamber2such that the arc portion18ais disposed between the engaging portion17and the inner peripheral surface of the casing1and the projection18bis disposed in the engaging groove17cwith a play.

By disposing the valve body18in this manner, the fluid passage5comprising a gap defined by the first to third backflow grooves18cto18e,the tip end surface of the projection18band the bottom surface of the engaging groove32fis formed between the valve body18and the engaging portion17. The viscous fluid can pass through the fluid passage5. Since the width d of the arc portion18ais set wide so that the arc portion18acomes into contact with the tip ends17aand17bof the engaging portion17, when the casing1is rotated around the rotor7in the braking force exhibiting direction X, a sliding area between the outer peripheral surface of the arc portion18aand the inner peripheral surface of the casing1is large and thus, the adhesion between the valve body18aand the casing1is enhanced, and the sealing performance can be enhanced.

As shown inFIG. 30, the resilient member19comprises a leaf spring which is curved such that its one surface projects. Although a member which is bent into a substantially L-shape as viewed from side is employed as the resilient member19in this embodiment, the resilient member19is not limited to this, and a member which is bent into an arc shape as viewed from side can also be employed.

It is preferable that the resilient member19has a notch19awhich passes through the resilient member19in its thickness direction. With this notch19a,when the casing1rotates around the rotor7in the non-braking force exhibiting direction Y, the viscous fluid moves through the notch19aeasily, and it is possible to present the viscous fluid generated when the viscous fluid passes through the fluid passage5from increasing as compared with a case in which no notch19aexists. With this, it is possible to reduce the viscous fluid generated at that time to an extremely low level. The same effect can also be obtained by forming a hole passing through the resilient member19in its thickness direction instead of the notch19a.

The resilient member19is provided in the fluid passage5such that the fluid passage5is not closed when no load is applied. More concretely, as shown inFIGS. 31 and 32, the resilient member19is disposed in the fluid passage5such that one surface of the resilient member19abuts against the other side surface of the projection18bof the valve body18, and the other surface abuts against an inner surface of the other tip end17bof the bifurcated tip ends of the engaging portion17opposed to the other side surface of the18b.It is of course possible to reverse the positional relation between the one surface and the other surface of the resilient member19, and to dispose the resilient member19in the fluid passage5.

The rotary damper D9having the above-described structure functions as follow. That is, when the rotary damper D9is applied to a subject to be controlled which opens and closes and when the subject to be controlled is closed, as shown inFIGS. 31(a) and32(a), the valve body18is biased by the resilient member19disposed in the fluid passage5, one of the side surfaces of the projection18bis in abutment against the inner surface of the one tip end17aof the bifurcated tip ends formed on the engaging portion17. When the valve body18is in this position, the fluid passage5is fully opened.

Here, the rotary damper D9is disposed such that the casing1is fixed to the subject to be controlled, the rotor7is connected to the support shaft which is a rotation center of the subject to be controlled, and as the subject to be controlled rotates, the casing1rotates around the rotor7.

If the subject to be controlled rotates in the opening direction, the casing1rotates in the braking force exhibiting direction X (seeFIG. 28). With this, the partition wall4pushes the viscous fluid in the fluid chamber2. Since the rotor7is provided such that the rotor7does not rotates even if the subject to be controlled rotates, if the partition wall4pushes the viscous fluid, the valve body18receives the pressure of the viscous fluid, the valve body18moves in the braking force exhibiting direction X while pressurizing the resilient member19. With this, the resilient member19is deformed as shown inFIGS. 31(b) and32(b), the gap between the opposed surfaces of the projection18bof the valve body18and the other tip end17bof the engaging portion17is reduced, and an opening area of the third backflow groove18ein the fluid passage5is reduced. Therefore, the flow rate of the viscous fluid passing through the fluid passage5is limited. The limiting degree of the flow rate of the viscous fluid is proportional to the magnitude of the deformation of the resilient member19, and as the deformation of the resilient member19is greater, the flow rate of the viscous fluid passing through the fluid passage5is reduced.

Therefore, when the rotational moment of the subject to be controlled is small and the load applied to the rotary damper D9is small, the pressure of the viscous fluid received by the valve body18is also small, and deformation of the resilient member19caused when the valve body18moves is also small. Therefore, a resistance generated when the viscous fluid passes through the fluid passage5is also small and the braking force exhibited by the rotary damper D9is also small. On the other hand, when the rotational moment of the subject to be controlled is great and the load applied to the rotary damper D9is great, the pressure of the viscous fluid received by the valve body18is high and the deformation of the resilient member19caused when the valve body18moves is also great. Therefore, the resistance generated when the viscous fluid passes through the fluid passage5is also great and the braking force exhibited by the rotary damper D9is also great.

According to this rotary damper D9, as the load is increased, the fluid passage5can automatically be closed gradually. Therefore, it is possible to limit the flow rate of the viscous fluid passing through the fluid passage5such that the flow rate is gradually reduced. Thus, when the magnitude of the load is varied, it is possible to reduce the variation of the rotation speed of the subject to be controlled to an extremely small value even if the rotary damper D9is not operated at all.

When a predetermined or higher load is applied, as shown inFIGS. 31(c) and32(c), the resilient member19is largely deformed and the fluid passage5is completely closed such that the gap between the opposed surfaces of the projection18bof the valve body18and the other tip end17bof the engaging portion17is eliminated. With this, the viscous fluid can not move through the fluid passage5and thus, the rotary damper D9exhibits greater braking force.

When the subject to be controlled is closed on the contrary, as the subject to be controlled rotates in its closing direction, the casing1rotates in the non-braking force exhibiting direction Y (seeFIG. 28). With this, the partition wall4pushes the viscous fluid in the fluid chamber2in the opposite direction. The valve body18receives the pressure of the viscous fluid pushed by the partition wall4and the biasing force of the resilient member19, and the valve body18moves in the non-braking force exhibiting direction Y, and the valve body18is returned to its original position shown inFIGS. 31(a) and32(a). With this, the fluid passage5is brought into the fully opened state. Therefore, a large amount of viscous fluid moves through the fluid passage5and thus, the rotary damper D9does not exhibit a braking force to a degree that affects the rotational motion of the subject to be controlled.

The present invention is not limited to the above-described structure, and the valve body18may be formed into a substantially rectangular solid having a width smaller than that of the engaging groove17c,and the backflow groove through which the viscous fluid can pass may be formed in two intersecting surfaces. The partition wall4may project from the outer peripheral surface of the rotor7, the tip end surface thereof may slide on the inner peripheral surface of the casing1, and the inner peripheral surface of the casing1may be provided with the engaging portion17having the engaging groove17c.The engaging portion17may be formed into a projecting shape, and the valve body18may be formed into a recess shape.

The present invention provides an auto part having the rotary damper according to the embodiment. Here, the term “auto part” is not especially limited, but typical examples of the auto part are a glove box, a console box, a reclining seat and an arm rest. The auto part will be explained in detail below based on embodiments illustrated in the drawings.

FIGS. 33 and 34show the glove box disposed in an opening formed in an instrument panel of an automobile. If the rotary damper D9of the embodiment 9 is applied to control the rotational motion of the glove box100, the rotary damper D9is provided on a connected portion between the glove box100and its support body (instrument panel supporting the glove box100)110.

The box body120of the glove box100is provided at its lower opposite sides with base portions120aand120b.The base portions120aand120bare connected to a support body110which supports the box body120through support shafts130aand130b,respectively. The box body120rotates around the support shafts130aand130bso that an accommodating section140which is a space formed in the box body120for accommodating articles rotates.

The casing1of the rotary damper D9is fixed to the box body120of the glove box100, and the rotor7is connected to the support shaft130a.Although the rotary damper D9is provided only on one side of the box body120in the embodiment shown inFIG. 33, the rotary dampers D9may be disposed on the opposite sides of the box body120of course. The casing1of the rotary damper D9may be fixed to the support body110. In this case, the rotor7is connected to the support shaft130aso that the rotor7can rotate in the casing1as the box body120rotates.

According to the glove box100having the above-described structure, if the box body120rotates in its opening direction, the accommodating section140turns. At that time, the magnitude of the rotational moment of the box body120is different between a case in which an article is accommodated in the accommodating section140and a case in which no article is accommodated in the accommodating section140. Even if the article is accommodated in the accommodating section140, the magnitude of the rotational moment of the box body120is varied depending upon the weight of the article. Therefore, a load applied to the rotary damper D9is varied depending upon the presence or absence of the article accommodated in the accommodating section140and the weight of the article. According to the rotary damper D9, however, since the exhibited braking force can automatically be adjusted in accordance with the variation in load, the variation in rotation speed caused by variation in rotational moment of the box body120can be reduced to an extremely small value even if the rotary damper D9is not operated at all.

On the other hand, when the box body120is to be closed, since the damping function of the rotary damper D9does not act, the box body120can rotate freely.

FIGS. 35 and 37show the console box disposed in the automobile. The console box200includes a double lid structure comprising an outer lid210and an inner lid220. If the rotary damper D3of the embodiment 3 is applied to control the rotational motion of the double structure, a leg1kprojecting from the casing1of the rotary damper D3is mounted to a body portion230of the console box200. With this, the casing1is fixed, a base end of a frame220aconstituting the inner lid220and a base end of a frame210aconstituting the outer lid210are connected to the inner shaft13.

As shown inFIG. 37, the inner lid220of the console box200includes an accommodating section220bof an article, and its weight is largely varied between a case in which sufficient articles are accommodated and a case in which no article is accommodated. When the inner lid220and the outer lid210are closed together, the weight of the outer lid210is also added to the weight of the inner lid220. Therefore, the rotational moment of the inner lid220is largely varied between a case in which no article is accommodated in the inner lid220and only the inner lid220is closed and a case in which sufficient articles are accommodated in the inner lid220and the inner lid220and the outer lid210are closed together.

According to the rotary damper D3, however, the magnitude of the exhibited braking force can automatically be adjusted in accordance with the variation in load such that when the load is small, the exhibited braking force becomes small, and when the load is great, the exhibited braking force becomes great. Therefore, when the rotational moment of the inner lid220is varied, it is possible to reduce the variation in rotation speed of the inner lid220to an extremely small value without operating the rotary damper D3.

When the inner lid220is opened, since the damping function of the rotary damper D3does not act, the inner lid220can rotate smoothly.

Further, since the rotary damper D3includes the click mechanism12, the inner lid220can be independent in its fully opened position.

FIGS. 38 and 40shows a reclining seat disposed in an automobile. If the rotary damper D2of the embodiment 2 is applied to control the rotational motion of the seat back310of the reclining seat300, the rotary damper D2is disposed on one of connected portions of the opposite sides between a seat back310and a seat cushion320where the reclining mechanism330is not provided shown inFIG. 39. More concretely, as shown inFIGS. 39 and 40, an upper hinge bracket350fixed to the seat back310is rotatably mounted on a support shaft340which supports the seat back310, and a lower hinge bracket360fixed to the seat cushion320is mounted on an outer side of the upper hinge bracket350, the rotary damper D2is connected to the support shaft340from outside of the lower hinge bracket360, and the casing1is connected to the upper hinge bracket350through a mounting screw370so that the casing1can rotate around the support shaft340as the seat back310rotates. InFIG. 40, a symbol380represents a nut which is threaded around a screw portion340aformed on a tip end of the support shaft340for mounting the rotary damper D2on the support shaft340.

As shown inFIG. 38, a reclining mechanism330capable of adjusting a position (inclination angle) of the seat back310in stages is provided on one of the connected portions on opposite sides of the seat back310and the seat cushion320. However, if only the reclining mechanism330is used, since the reclining mechanism330includes a spring member331which biases the seat back310forward, if an operating lever332is lifted up carelessly to release the locked state established by meshing gears333and334, there is an adverse possibility that the seat back310abruptly rotates forwardly and collides against a seated passenger and offends the passenger.

In this regard, according to the reclining seat300having the rotary damper D2, the rotary damper D2exhibits the braking force to the seat back310which turns forward, the rotational motion of the seat back310can be moderated against the biasing force of the spring member331and thus, this inconvenience can be overcome.

The rotational moment of the reclining seat300is varied between a case in which a head rest (not shown) is mounted on the seat back310and a case in which the head rest is detached. Therefore, the rotation speed of the seat back310is largely varied depending upon presence and absence of the head rest.

According to the rotary damper D2, however, it is possible to automatically adjust the magnitude of the exhibited braking force in accordance with the variation in load such that when the load is small, the exhibited braking force becomes small, and when the load is great, the exhibited braking force becomes great. Therefore, when the rotational moment of the seat back310is varied, it is possible to reduce the rotation speed of the seat back310to an extremely small value without operating the rotary damper D2at all.

When the seat back310is rotated rearward, since the damping function of the rotary damper D2does not act, the seat back310can be rotated with a small force.

FIGS. 41 and 42shows an arm rest which can be accommodated in an accommodating recess formed in a front surface of the seat back which constitutes a rear seat of an automobile in a state in which the arm rest stands. If the rotary damper D7of the embodiment 7 is applied to control the rotational motion of the arm rest400, the rotary damper D7is disposed inside of a body frame410of the arm rest400, and a projection it projecting from an outer periphery of the casing1is engaged with an engaging pin420projecting from the body frame410. With this, the casing1is fixed to the body frame410so that the casing1can turn around the support shaft430as the body frame410rotates in the longitudinal direction, and the rotor7is connected to the support shaft430using a connecting pin440.

The body frame410of the arm rest400is turnably supported by the support shaft430which is supported by a bracket450mounted on a seat back (not shown) which constitutes a rear seat of an automobile. A guide bar460is provided in the body frame410. Opposite ends of the guide bar460are disposed in arc guide grooves450aformed in the bracket450. A range in which the guide bar460can move in the guide groove450aas the body frame410turns is set as a rotation angle range of the arm rest400in the longitudinal direction.

The arm rest400has such a structure that the arm rest400can be used as an arm rest of a passenger, and the arm rest400can accommodate an article. Therefore, the rotational moment of the arm rest400is varied between a case in which an article is accommodated and a case in which no article is accommodated. Thus, the rotation speed of the arm rest400is largely varied depending upon presence or absence of the article.

According to the rotary damper D7, however, it is possible to automatically adjust the magnitude of the exhibited braking force in accordance with the variation in load such that when the load is small, the exhibited braking force becomes small, and when the load is great, the exhibited braking force becomes great. Therefore, when the rotational moment of the arm rest400is varied, it is possible to reduce the rotation speed of the arm rest400to an extremely small value without operating the rotary damper D7at all.

Further, when the arm rest400is used, the arm rest400which is accommodated in the accommodating recess (not shown) formed in the front surface of the seat back in its standing attitude is pulled out forward, and it is rotated forward. At that time, even if a user moves his or her hand off the arm rest400, the arm rest400can rotate slowly by the damping function of the rotary damper D7, and the arm rest400can stop at its using attitude without generating an impact almost at all.

On the other hand, when the arm rest400is to be accommodated, since the damping function of the rotary damper D7does not act, the arm rest400can be rotated with a small force.

The present invention provides a rotational motion assistant mechanism which is characterized in that it has a spring member which biases a subject to be controlled in one direction is provided with the rotary damper of the embodiment so that rotation of the subject to be controlled in one direction is delayed against stress of the spring member. The invention will be explained in detail based on an illustrated embodiment.

FIGS. 43 and 45show a hoisting and lowering case having the rotational motion assistant mechanism according to an embodiment of the present invention. As shown in these drawings, the hoisting and lowering case500is connected to a fixed plate530through a movable arm510and an auxiliary arm520. If a user grasps a handle (not shown) and pulls it downward, the hoisting and lowering case500rotates from its accommodating position to its using position, and if the user pushes the hoisting and lowering case500upward, the hoisting and lowering case500is rotated from the using position to the accommodating position.

The rotational motion assistant mechanism of this embodiment includes a spring member20, and includes the rotary damper D1of the embodiment 1.

The spring member20biases a subject to be controlled in one direction. In this embodiment, the spring member20biases the hoisting and lowering case500which is the subject to be controlled upward. It is possible to employ an extension coil spring as the spring member20, but in this embodiment, a spiral-spring is employed. This is because that the spiral-spring has a merit that a small installation space suffices as compared with the extension coil spring.

One end20aof the spring member20which becomes a fulcrum is supported by a stationary portion, and the other end20bwhich becomes an acting point is supported by a movable portion. The spring member20is disposed such that as the spring member20is wound as the spring member20is rotated when the hoisting and lowering case500is lowered, energy for biasing the hoisting and lowering case500upward is accumulated.

In this embodiment, as the stationary portion which supports the one end20aof the spring member20, the groove1d(seeFIGS. 1 and 44) formed in the casing1of the rotary damper D1fixed to the fixed plate530is utilized. That is, the one end20aof the spring member20is engaged and supported in the groove1d.By providing the groove1dfor supporting the one end20aof the spring member20in the casing1of the rotary damper D1, there is a merit that it is unnecessary to separately form a supporting portion for supporting the one end20aof the spring member20on the fixed plate530or the like. As a movable portion for fixing the other end20bof the spring member20, a retaining portion510aformed on the movable arm510is utilized.

A location of the rotary damper D1is not limited, but in this embodiment, as shown inFIG. 44, the rotary damper D1is fixed to the fixed plate530such that the casing1is located in a space formed at a substantially center of the spring member20comprising the spiral-spring. With this structure, since the entire rotational motion assistant mechanism including the spring member20and the rotary damper D1can be reduced in size, there is a merit that the installation space of the rotational motion assistant mechanism can be reduced. It is of course possible to independently dispose the spring member20and the rotary damper D1.

The rotational motion assistant mechanism having the above-described structure functions as follows. That is, as shown inFIG. 45, if the hoisting and lowering case500is lowered from the accommodating position to the using position, the movable arm510turns in the same direction (“lowering direction”, hereinafter) as the rotation direction of the hoisting and lowering case500. Since the other end20bof the spring member20is supported by the movable arm510, if the movable arm510turns in the lowering direction, the spring member20is wound up. Thus, the stress of the spring member20is increased as the hoisting and lowering case500is lowered. The stress of the spring member20functions as a force for supporting the lowering hoisting and lowering case500and thus, the rotational motion of the hoisting and lowering case500is moderated, and safety of the operation can be secured.

On the other hand, if the movable arm510turns as the hoisting and lowering case500is lowered, the rotor7connected to a support shaft540which rotates together with the movable arm510rotates in the counterclockwise direction inFIG. 1in the casing1. When the rotor7rotates in the counterclockwise direction in this manner, a resistance of the viscous fluid generated by the rock of the vane3becomes extremely small, and the braking force exhibited by the rotary damper D1becomes also small. Therefore, when the hoisting and lowering case500is lowered, the hoisting and lowering case500rotates without being affected by the damping effect of the rotary damper D1.

On the other hand, when the hoisting and lowering case500is hoisted toward the accommodating position from the using position, the stress of the spring member20functions as a force for hoisting the hoisting and lowering case500and thus, a user can lift the hoisting and lowering case500with a small force.

Since the one end20aof the spring member20is supported by the stationary portion, the spring member20can exhibit only stress within a given range. Thus, if only the spring member20is used, it is difficult to sufficiently assist the rotational motion of the hoisting and lowering case500. That is, since the hoisting and lowering case500includes a shelf550as shown inFIG. 43and can accommodate an article, the weight of the entire hoisting and lowering case500is varied between a case in which the article is accommodated in the hoisting and lowering case500and a case in which no article is accommodated in the hoisting and lowering case500or a case in which the entire weight of the articles is heavy, and the rotational moment of the hoisting and lowering case500is varied. Therefore, if there is provided only the spring member20which can exhibit only the stress in the given range, when the hoisting and lowering case500whose entire weight is light is lifted up from the using position to the accommodating position, the rotation speed of the hoisting and lowering case500is largely accelerated by the operating force of a user and the stress of the spring member20, and there is an adverse possibility that the hoisting and lowering case500is abruptly rotated and stops at the accommodating position, and a large impact is generated when the hoisting and lowering case500stops. On the other hand, if the biasing force of the spring member20applied to the hoisting and lowering case500is set small so as to reduce the impact caused when the hoisting and lowering case500stops, a burden of a user when the hoisting and lowering case500whose entire weight is heavy is lifted up from the using position to the accommodating position becomes large.

However, since the rotational motion assistant mechanism of this embodiment has the rotary damper D1, it is possible to overcome the inconvenience without requiring a user to do any special operation.

That is, according to the rotary damper D1, it is possible to automatically adjust the magnitude of the exhibited braking force in accordance with variation in load such that when the load is small, the exhibited braking force becomes small, and when the load is great, the exhibited braking force becomes great. Therefore, even when the rotational moment of the hoisting and lowering case500is varied, it is possible to adjust the biasing force of the spring member20applied to the hoisting and lowering case500without doing any operation. Thus, according to the rotational motion assistant mechanism of the embodiment, it is possible to always reduce an impact caused when the hoisting and lowering case500stops at the accommodating position irrespective of variation of rotational moment of the hoisting and lowering case500.

Further, according to the rotational motion assistant mechanism of this embodiment, since it is possible to always reduce the impact when the hoisting and lowering case500stops at the accommodating position, the biasing force of the spring member20applied to the hoisting and lowering case500can be set large within a range which does not hinder the using condition. Thus, even when the hoisting and lowering case500whose entire weight is heavy is lifted up to the accommodating position from the using position, it is possible to reduce the burden of the user.

If a predetermined or higher load is applied to the rotary damper D1, the rotary damper D1exhibits greater braking force. Thus, the biasing force of the spring member20applied to the hoisting and lowering case500(force for lifting the hoisting and lowering case500by the spring member20) can be reduced to substantially zero by the braking force, and the rotational motion of the hoisting and lowering case500can be stopped. The rotational motion assistant mechanism of the present invention can also be applied to various subjects in addition to the above-described hoisting and lowering case.

INDUSTRIAL APPLICABILITY

As explained above, according to the present invention, it is possible to provide a rotary damper which can automatically adjust an exhibited braking force in accordance with variation in load caused by variation of rotational moment of a subject to be controlled, and which can reduce the variation in rotation speed of a subject to be controlled to an extremely small value.

Further, according to the present invention, it is possible to provide an auto part such as a glove box, a console box, a reclining seat, an arm rest and the like in which variation in rotation speed is small even if the rotational moment is varied.

Further, according to the present invention, it is possible to provide a rotational motion assistant mechanism capable of automatically adjusting a biasing force of a spring member applied to a subject to be controlled in correspondence with variation of rotational moment of the subject to be controlled.