JP2006052764A - Rotary damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary damper capable of supplementing a defect of an oil damper and providing sufficient damper effect. <P>SOLUTION: This rotary damper is provided with a fixed member 1, a rotary member 2 capable of rotating relative to the fixed member 1, a permanent magnet 4 provided on either of a fixed member side and a rotary member side, and a magnetic substance 3 provided on the other side of the fixed member side and the rotary member side to generate magnetic force between the permanent magnet and the magnetic substance. The fixed member 1 and the rotary member 2 are brought into pressure-contact by magnetic force to give friction force to a slide face when the rotary member rotates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotary damper for applying a braking force to a rotating body.

The conventionally known rotary damper described in Patent Document 1 incorporates a rotating body in a casing, and the casing is partitioned into a high pressure chamber and a low pressure chamber by blades provided on the rotating body. Then, as the blades rotate as the rotating body rotates, the viscous fluid is guided from the high pressure chamber to the low pressure chamber, and the braking force is exerted by the flow resistance generated in the moving process of the viscous fluid. is there.
JP 58-050342 A

As described above, since the conventional rotary damper has a viscous fluid placed in the casing as an oil damper and a braking force is obtained by the flow resistance of the viscous fluid, oil is inevitably required. The fact that oil is required in this way requires a seal member for preventing fluid leakage.
And in order to make the sealing function of the said sealing member perfect, since a sealing structure becomes complicated and it becomes large sized, this will cause a cost increase. Further, if the dimensional accuracy of the seal structure is increased in order to complete the sealing effect, there is a problem that the cost increases accordingly.

On the other hand, if the sealing function is to be satisfied without increasing the accuracy of the sealing structure, the tightening force of the sealing member must be increased. However, as the tightening force of the seal is increased, the friction increases, which affects the rotation of the rotating body, and the damper effect may become unstable. In addition, the life of the seal member is shortened, and as a result, the life of the rotary damper is also shortened.
Moreover, in order to provide the seal member, it is necessary to form and hold the seal groove. However, the formation of the seal groove itself is troublesome, which also causes an increase in cost.

Furthermore, the surface of the rotating shaft connected to the rotating body must be kept highly accurate in order to prevent oil leakage and minimize frictional resistance. If the processing accuracy is to be increased in this way, as a matter of course, the cost increases accordingly. In any case, the conventional oil damper not only limited its application, but also could not avoid the problem that its manufacturing cost increased significantly.
An object of the present invention is to provide a rotary damper that compensates for the drawbacks of an oil damper and that can exhibit a sufficient damper effect.

The rotary damper of the first invention includes a fixed member, a rotary member that is rotatable relative to the fixed member, a permanent magnet provided on either the fixed member side or the rotary member side, and the fixed member side or And a magnetic body that is provided on either side of the rotating member and generates a magnetic force with the permanent magnet. The fixed member and the rotating member are pressed against each other by the magnetic force, and the sliding member is placed on the sliding surface when the rotating member rotates. It is characterized in that a frictional force is applied.
In the above invention, the fixing member and the rotating member itself may be a permanent magnet or a magnetic body, or the permanent magnet and the magnetic body may be separated from the fixing member and the rotating member. In any case, it suffices that either the fixed member side or the rotating member side has a function as a permanent magnet and the other has a function as a magnetic body. The magnetic material includes a permanent magnet.

The second invention is based on the first invention, and is characterized in that a frictional force reducing layer for reducing the frictional force is provided on the sliding surface between the fixed member and the rotating member.
Note that the friction force reducing layer is a layer formed of a material having a small friction coefficient, for example, and a member constituting the sliding surface such as a fixed member or a rotating member itself may be formed of a material having a small friction coefficient. Alternatively, the sliding surface may be coated with a material having a small friction coefficient.

3rd invention presupposes the said 2nd invention, and has the characteristics in the point which comprised the said friction-force reduction layer with the sliding member separate from the said fixing member and rotation member.
The fourth invention is based on the third invention and is characterized in that the sliding member is made of a plastic material.
5th invention presupposes the said 2nd-4th invention, and has the characteristics in the point which made the said frictional force reduction layer hold | maintain grease.

According to the first to fifth inventions, it is not necessary to hold a viscous fluid such as oil around the rotating member in order to obtain a braking force during rotation.
Therefore, the rotary damper of the present invention does not require a seal mechanism for preventing oil leakage. Thus, since the seal mechanism is not used, the structure of the rotary damper can be simplified and the manufacturing cost can be kept low.
In addition, the size can be reduced by the amount that the seal mechanism is unnecessary.

According to the second to fifth inventions, even if the pressure contact force due to the magnetic force is strong, the frictional force can be reduced and the sliding resistance, that is, the braking force can be adjusted.
Further, there is an effect that the transition from the stopped state to the rotating state becomes very smooth at the time of starting to rotate.
Particularly, in the third and fourth inventions, the frictional force reducing layer is constituted by a sliding member separate from the fixed member and the rotating member, so that the configuration of each member can be simplified. Further, since the frictional force can be adjusted only by the sliding member, the frictional force can be easily adjusted.
According to the fifth aspect of the invention, the shear resistance of the grease held on the sliding member acts to increase the dynamic friction resistance when sliding between the fixed member and the rotating member, and while applying braking force from the start, smooth Rotation is possible.
In addition, the effect that the transition from the stopped state to the rotating state becomes very smooth at the start of the rotation is more remarkable than when no grease is used.

A first embodiment of the present invention shown in FIG. 1 is a rotary damper in which a gear shaft 2 is rotatably incorporated in a housing 1, and a braking force is generated when the gear shaft 2 is rotated with the housing 1 fixed. It is designed to be demonstrated.
In the first embodiment, the housing 1 and the gear shaft 2 are made of resin to reduce the weight.
The housing 1 includes a bottom plate 1a and a cylindrical main body 1b standing on the bottom plate 1a. A magnetic plate 3 made of a magnetic material is fixed to the bottom plate 1a in the main body 1b.
The gear shaft 2 includes a gear portion 2a having a gear formed on the outer periphery and a cylindrical holder 2b. A permanent magnet 4 is fixed in the holder 2b. The permanent magnet 4 may be fixed to the holder 2b by adhesion, or may be fixed by magnetic force by providing a magnetic body on the holder 2b side.

The holder 2b is incorporated in the main body 1b of the housing 1 to constitute a rotary damper. A predetermined gap g1 is provided between the permanent magnet 4 and the magnetic plate 3 in a state where the end surface (the lower end in FIG. 1) of the holder 2b of the gear shaft 2 and the magnetic plate 3 are in contact with each other. ing.
In addition, a driving force is transmitted to the gear shaft 2 through the gear portion 2a to enable relative rotation between the gear shaft 2 and the housing 1.
In the first embodiment, the housing 1 is a fixing member of the present invention, and the magnetic plate 3 is a magnetic body provided on the fixing member side. The gear shaft 2 is a rotating member of the present invention, and the permanent magnet 4 is a permanent magnet provided on the rotating member side.
However, the permanent magnet 4 may be fixed to the housing 1 side, and the magnetic plate 3 that is a magnetic body may be fixed to the gear shaft 2 side.

Hereinafter, a mechanism for applying a braking force in the rotary damper will be described.
As described above, when the gear shaft 2 is incorporated in the housing 1, an attractive force is generated between the permanent magnet 4 and the magnetic plate 3 by the magnetic force of the permanent magnet 4 in the holder 2b. The end surface of the holder 2b is brought into pressure contact with the magnetic plate 3 by this attractive force, and this pressure contact surface corresponds to the sliding surface of the present invention.
Accordingly, a vertical drag corresponding to the attractive force is applied to the magnetic plate 3, and when the gear shaft 2 rotates, a frictional force proportional to the vertical drag is generated on the sliding surface. Acts as a braking force against rotation.

Thus, since the braking force at the time of rotation can be applied by the attractive force due to the magnetic force, it is not necessary to use a viscous fluid as in the prior art. For this reason, a space for holding the viscous fluid and a sealing mechanism are not required, and accordingly, downsizing and cost reduction can be realized.
Further, since the housing 1 as a fixed member and the gear shaft 2 as a rotating member are attracted by the attractive force of the permanent magnet 4, they are integrated only by assembling, for example, the housing so that the gear shaft 2 does not come out. There is no need to provide a cap or the like on 1. Accordingly, the structure becomes simple and the cost can be reduced.

Further, a gap g1 is provided between the permanent magnet 4 and the magnetic plate 3, and the magnetic force is adjusted by adjusting the size of the gap g1, and as a result, the braking force is adjusted. Can do. For example, the gap g1 may be zero, and the space between the permanent magnet 4 and the magnetic plate 3 may be a sliding surface.
Alternatively, the permanent magnet 4 may be bonded to the housing 1 side, the magnetic plate 3 may be fixed to the gear shaft 2 side, and a space between them may be used as a sliding surface.

The second embodiment shown in FIG. 2 is different from the rotary damper of the first embodiment in that the sliding member 5 is provided on the housing 1 side. The same reference numerals as those in FIG.
In the rotary damper according to the second embodiment, a sliding member 5 made of a nonwoven fabric is bonded onto the magnetic plate 3 on the housing 1 side, grease is contained in the nonwoven fabric, and the end surface of the holder 2b is attached to the sliding member 5. And the permanent magnet 4 are in contact with each other. In other words, the holder 2b of the second embodiment has a shorter axial length than the holder 2b of the first embodiment, and the end face and the surface of the permanent magnet 4 are flush with each other.
Thereby, the space between the end surface of the holder 2b and the surface of the permanent magnet 4 and the sliding member 5 becomes the sliding surface of the present invention. However, a space may be provided between the permanent magnet 4 and the sliding member 5, and only the end surface of the holder 2b and the sliding member 5 may be used as the sliding surface.
Further, the length of the holder 2b in the axial direction may be shortened so that the end surface thereof does not contact the surface of the sliding member 5. In that case, the surface between the permanent magnet 4 and the sliding member 5 is a sliding surface.

Also in the rotary damper of the second embodiment, as shown in FIG. 2, in the state where the gear shaft 2 which is the rotating member of the present invention is incorporated in the housing 1 which is the fixing member of the present invention, The gear shaft 2 is pressed against the sliding member 5 by the magnetic force of the permanent magnet 4. Accordingly, a frictional force is generated on the sliding surface, which becomes a braking force during rotation.
In the rotary damper of the second embodiment, since the sliding member 5 containing grease is interposed on the sliding surface, the start of rotation of the gear shaft 2 relative to the housing 1 is made smooth by this grease. At the same time, smooth rotation is achieved while applying an appropriate braking force during rotation.
This is because the grease acts to lower the friction coefficient of the sliding surface at the start of rotation and starts the rotation more smoothly. However, during the rotation, it exerts a shearing resistance due to viscosity and imparts a braking force. Because.

The difference in characteristics between when the grease is included in the sliding member 5 and when it is not included is shown in the graph of FIG. This graph is a graph showing the rotational torque T with respect to the movement amount.
When grease is not included, torque T1 corresponding to the static frictional force of the sliding surface is required at the time of starting as shown by the characteristic line b. However, once the rotation starts, the frictional force between the sliding member 5 and the holder 2b and the permanent magnet 4, that is, the sliding surface becomes a dynamic frictional force, so that the resistance force decreases rapidly and the torque T2 Will move in. That is, there is a difference in the torque required for the movement between the start of movement and the start of movement. For this reason, when constant power is input to the gear shaft 2, a sudden torque change may occur between the start of rotation and the constant rotation speed, and smooth rotation may not be possible. It was.

On the other hand, when grease is included, as shown by the characteristic line a, an operating force that overcomes the static frictional force of the sliding surface is required at the time of starting, but the sliding surface does not have grease. Therefore, the static frictional force is small. Accordingly, the rotation starts with a torque T3 smaller than the torque T1. After the rotation starts, the shear resistance (viscosity resistance) of grease acts between the two members, that is, the sliding surface, so that the resistance of the sliding surface is not rapidly decreased. That is, the difference in rotational torque T between the start time and after the start is small, and smooth rotation can be realized.
In addition, since the sliding member 5 made of a nonwoven fabric containing grease is sandwiched between the permanent magnet 4 and the magnetic plate 3 by a magnetic force, the grease exudes moderately from the sliding member 5.

As described above, the rotary damper according to the second embodiment also does not require a viscous fluid for imparting resistance, so a space for holding the viscous fluid and a seal mechanism are not required, and the size and size of the rotary damper can be reduced. Cost reduction can be realized.
Further, since the housing 1 as a fixed member and the gear shaft 2 as a rotating member are attracted by the attractive force of the permanent magnet 4, they are integrated only by assembling, for example, the housing so that the gear shaft 2 does not come out. There is no need to provide a cap or the like on 1. Accordingly, the structure becomes simple and the cost can be reduced.
In the second embodiment, the sliding member 5 is fixed to the magnetic plate 3, but the sliding member 5 may be fixed to the gear shaft 2 side that is a rotating member.
Alternatively, the permanent magnet 4 may be fixed to the housing 1 side, the magnetic plate 3 may be fixed to the gear shaft 2 side, and the sliding member 5 may be interposed between these sliding surfaces.

The third embodiment shown in FIG. 4 is an example in which the housing 1 of the rotary damper of the first embodiment shown in FIG. 1 is made of a magnetic material and the magnetic plate 3 is omitted. Other configurations are the same as those in the first embodiment, and the same components as those in FIG. 1 are denoted by the same reference numerals.
Accordingly, a frictional force corresponding to the attractive force between the permanent magnet 4 and the bottom plate 1a of the housing 1 acts on the sliding surface between the holder 2b and the bottom plate 1a to become a braking force during rotation.
Therefore, a viscous fluid for applying a braking force is unnecessary, and the same effect as in the first embodiment can be obtained.
Note that the length of the holder 2a in the axial direction is increased by the amount that the magnetic plate 3 is omitted, and a gap g2 is formed between the permanent magnet 4 and the bottom plate 1a. Therefore, it is possible to adjust the braking force by adjusting the magnetic force by adjusting the size of the gap g2.

Further, the fourth embodiment shown in FIG. 5 is an example in which the housing 1 of the rotary damper of the second embodiment shown in FIG. 3 is made of a magnetic material and the magnetic plate 3 is omitted. The other configuration is the same as that of the second embodiment, and the same components as those in FIG.
Accordingly, a frictional force corresponding to the attractive force between the permanent magnet 4 and the bottom plate 1a acts on the sliding surface between the holder 2b and the permanent magnet 4 and the sliding member 5, and becomes a braking force during rotation. .
Therefore, a viscous fluid for applying a braking force is unnecessary, and the same effect as in the second embodiment can be obtained. Furthermore, the effect of the sliding member 5 is the same as that of the second embodiment.

In the third and fourth embodiments, since the magnetic plate 3 can be omitted by forming the housing 1 from a magnetic material, the number of parts can be reduced and the axial dimension of the housing 1 can be reduced. It can also be made smaller.
However, if the housing 1 is made of resin rather than a magnetic material, the manufacturing cost can be reduced and the weight can be reduced.
Further, by fixing the permanent magnet 4 to the housing 1 side and forming the gear shaft 2 from a magnetic material, a braking force is applied using the magnetic force between the permanent magnet 4 and the holder 2b of the gear shaft 2. You can also

Furthermore, in the said 1st-4th embodiment, you may use a permanent magnet as a magnetic body of this invention. For example, if a plate-like permanent magnet is provided instead of the magnetic plate 3 of the first and second embodiments, or if the housing 1 is formed of a permanent magnet in the third and fourth embodiments, the space between the permanent magnet 4 It is also possible to increase the braking force by increasing the attractive force.
In the first to fourth embodiments, the housing 1 is a fixing member of the present invention, and the gear shaft 2 is a rotating member. However, the rotating member does not have to be a gear shaft, and can rotate even without a gear. A shaft that can input the driving force for the motor may be used.
Further, the relationship between the fixed member and the rotating member is relative, and either the fixed member or the rotating member may be used. That is, the housing 1 side may be connected to a drive source (not shown) and the gear shaft 2 side may be fixed.

In the second and fourth embodiments, the non-woven sliding member 5 is used. However, a plastic plate having a low friction coefficient may be used as the sliding member. This plastic plate sliding member is easy to form. Note that the sliding member may be interposed between the sliding surfaces without being fixed to any member.
In order to prevent the frictional force based on the magnetic force from becoming too strong, a frictional force reducing layer may be interposed on the sliding surface. In addition to the sliding member, the frictional force reducing layer is provided as follows. It can also be configured. That is, at least one of the sliding surfaces is coated with a low friction material, or the entire member constituting the sliding surface is configured with a material having a small friction coefficient to configure the friction force reducing layer. You can also.

It is sectional drawing of 1st Embodiment of this invention. It is sectional drawing of 2nd Embodiment. It is the graph which showed the relationship between the amount of relative movement at the time of rotation, and rotational torque. It is sectional drawing of 3rd Embodiment. It is sectional drawing of 4th Embodiment.

Explanation of symbols

1 Housing 2 Gear Shaft 3 Magnetic Plate 4 Permanent Magnet 5 Sliding Member

Claims (5)

  A fixed member, a rotating member that is rotatable relative to the fixed member, a permanent magnet provided on either the fixed member side or the rotating member side, and provided on either the fixed member side or the rotating member side And a magnetic damper that generates a magnetic force with the permanent magnet, presses the fixed member and the rotating member with the magnetic force, and applies a frictional force to the sliding surface when the rotating member rotates.   The rotary damper according to claim 1, wherein a frictional force reducing layer for reducing a frictional force is provided on a sliding surface between the fixed member and the rotating member.   The rotary damper according to claim 2, wherein the frictional force reducing layer is configured by a sliding member separate from the fixed member and the rotating member.   The rotary damper according to claim 3, wherein the sliding member is made of a plastic material.   The rotary damper according to any one of claims 2 to 4, wherein grease is held in the friction force reducing layer.

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