JP4635466B2 - Bearing having rotation stop means - Google Patents

Description

  The present invention relates to a bearing having rolling elements.

Conventional bearings with rolling elements are components that enable relative rotation around a rotating shaft via the rolling elements, but the technology of conventional bearings has been described as `` for high loads such as radial loads, thrust loads, and moments. It is related to the so-called “rotation”, such as “How can it withstand and still have low rotational resistance and ensure sufficient reliability?”, And there is no technology or means to stop the relative rotation or keep the stopped state equal.
JP2001-279702 JP 58-24627 JP 10-237901

The inventor has been engaged in the development of a bucket-type attachment (hereinafter referred to as a bucket) that is attached to a construction machine such as a hydraulic excavator for many years. Some buckets are equipped with a rotating device composed of a hydraulic motor, a bearing, or the like to rotate the bucket itself.
When the bucket receives an external force that is excessively greater than the force that can be maintained by the rotating device, there is a problem that the bucket rotates against the designer's intention. Specifically, when excavating hard soil such as natural ground, there was a problem that the excavation resistance counteracted the brake valve of the hydraulic motor and the bucket was rotated arbitrarily, so that excavation was virtually impossible. .
For this reason, in a bucket with only a hydraulic motor attached, it is highly probable that the excavation work with a high load will be abandoned or the hydraulic motor will be damaged. The drilling was set high.
Also, this bucket has a gripping function, and if the center of gravity of a member such as a long object is removed and gripped, the rotational moment due to gravity will resist the brake valve of the hydraulic motor and cause the bucket to rotate. Yes, it was very dangerous.

In view of such a current situation, the present inventor has developed a mechanical locking method using pins as seen in Patent Document 1. This mechanical locking method has an excellent advantage that it can be securely locked, but has a disadvantage that the position locked in the circumferential direction is determined by the hole position and the like and cannot be locked at a fine angle pitch. It was.
In another example, a method using friction welding using a hydraulic cylinder as in Patent Documents 2 and 3 has been devised. This locking method has the advantage that it can be locked at an arbitrary position of 360 degrees in the circumferential direction, but the brake torque is weak with a single unit, so a large number must be installed, and it is practical in terms of installation location and cost It was scarce.

As mentioned above, buckets with a rotating function and other attachments such as crushers and forks with the same rotating function, as well as general rotating bodies and swiveling bodies, usually rotate with a slight force. `` I want you to do it, but if you don't, I want you to stop firmly enough to erase the fact that it was rotating at an arbitrary position of 360 degrees in the circumferential direction. '' Annoyed.
In view of such a current situation, an object of the present invention is to solve the above problems.

  In order to solve the problem, in a bearing having an inner ring, an outer ring, and a rolling element, an annular piston and a ring in which the annular piston is disposed have a locking portion that transmits a circumferential force to each other, and the piston is The bearing is moved in the axial direction of the bearing, and the top part of the bearing is provided so that a ring in which the bearing is not provided can be pressed against the surface. In order to obtain further effects, a friction material is interposed on the friction surface, or the space is sealed with a seal.

  Alternatively, in a bearing having an inner ring, an outer ring, and a rolling element, at least one or more non-annular pistons move in the axial direction of the bearing, and the top of each piston is provided in a ring so that surface contact can be made. Make bearings. Similarly, in order to obtain further effects, a friction material is interposed on the friction surface, or the space is sealed with a seal.

As a more powerful means, the following bearings with multiple friction surfaces are manufactured.
In a bearing having an inner ring, an outer ring, and a rolling element, an annular groove is provided between the inner ring and the outer ring. A bearing having a plurality of annular plates alternately engaged with the outer ring and having means capable of pressurizing the uppermost plate is manufactured.

1) If an annular piston is installed in the bearing, it can have a large pressure receiving area, and the piston can be installed at a distance away from the center of rotation. This means that the two elements that make up the brake torque, the pressing force and the length of the moment arm, are earned together. In addition, since the top of the piston is in surface pressure contact with the mating surface, it is possible to obtain a practically necessary and sufficient huge brake torque that may be superior to mechanical locking means such as a pin. As a result, the rotating body can be stopped or held at an arbitrary position of 360 ° on the circumference.
2) The effect is amplified if a friction material is interposed on the friction surface, and a more stable effect can be maintained if the space is sealed.
3) The same effect can be obtained with a bearing having a non-annular piston.
4) If a bearing having a plurality of annular plates that are alternately engaged with the inner ring and the outer ring, that is, a bearing in which a plurality of friction surfaces are stacked in series, an even stronger frictional force proportional to that, that is, brake torque, Obtainable.
5) In summary, conventionally, in order to stop or keep the rotating body rotating, new parts and devices have been added to locations other than the bearings, and a new space for this purpose is required. However, according to the present invention, the bearing itself is completed, and an element part having a new function is obtained.

  A conventional bearing will be described with reference to a sectional view of FIG. A conventional bearing 1 is composed of three main elements, an outer ring 2, an inner ring 3 and a rolling element 4. Here, the rolling elements use balls, but there are also rollers. In addition to these, the bearing mounting bolt hole 5, the seal 6 and the gear 7 are provided, and the outer ring 2 and the inner ring 3 can be freely rotated via the rolling elements 4. A cage for the rolling element 4 is not shown.

Several embodiments of the invention described in claim 1 will be shown for such a conventional bearing. First, an embodiment in which an annular piston is provided in the outer ring will be described. An example is shown in FIGS. 2 and 3 and will be described below.
As shown in FIG. 3, which is a cross-section AA in FIG. 2, the piston 8 is annular. As shown in FIG. 2, an annular hole 9 is also formed in the outer ring 2 in which the piston is provided. Two seal grooves 10 are provided in the hole 9, and a seal 11 is inserted to prevent fluid leakage. This seal groove may be provided on the piston 8 side. The seal 11 is an O-ring, but other seal members may be used. A fluid such as pressure oil passes through a pipe line from a port 12 provided in at least one place on the outer ring 2 and exerts pressure on the piston bottom surface 13 so that the piston 8 performs linear motion.
The top portion 14 of the piston 8 is a plane perpendicular to the traveling direction so as to be in contact with the mating surface, that is, in surface contact. The top portion 14 has a similar shape to the piston bottom surface 13 so as to ensure a pressure contact area.

In order to stop or maintain the relative rotation of the inner and outer rings by the frictional force generated on the piston top portion 14 and the relative surface, a circumferential force must be transmitted from the wheel to the piston 8. In other words, the annular piston 8 requires a locking portion that engages with the hole 9, and that portion transmits a circumferential force. On the other hand, if there is no locking part, the piston is annular, so it rotates with the other wheel and the frictional force on the friction surface makes no sense.
As shown in FIG. 2, the locking portion is provided with a plurality of convex locking portions 15a in the circumferential direction on the side wall of the hole 9, and a concave locking portion that fits the opposing piston 8. 16a is formed. In the embodiment, the locking portions are provided on the two side walls, but one side wall may be used. A concave locking portion may be formed on the side wall of the hole 9, and a convex locking portion may be formed on the opposing piston 8. Further, the locking portion may have a spline shape in which these are connected.

  The action of the piston 8 is that the piston 8 moves parallel to the bearing rotation axis, and the piston top portion 14 makes a frictional force by vertically and evenly contacting the flat surface portion of the ring not including the piston 8, that is, the inner ring 3. Is generated, and the relative rotational movement between the inner ring 3 and the outer ring 2 is stopped, or the stopped state is maintained.

  Also, as shown in FIG. 4, the piston may be arranged such that a collar 17 is attached to the inner ring and the piston presses against it. By the way, this aims to increase both the pressure receiving area and the length of the arm of the brake moment by increasing the distance from the center of rotation more than the embodiment of Fig. 2, and both increase the brake torque. It is effective to make it. In both FIGS. 2 and 4, the piston presses the inner ring and stops the relative rotational movement of the inner ring and the outer ring.

  Furthermore, as shown in FIG. 5, a bearing in which two pistons are provided in the outer ring may be used by combining the embodiments of FIGS. It is possible to move two pistons simultaneously from one port by integrating pipes that supply fluid such as pressure oil to the two pistons.

  So far, only the examples in which the piston is installed in the outer ring have been introduced. However, since the piston may be installed in the inner ring, some examples will be introduced. The embodiment shown in FIGS. 6 and 7 is an example in which one piston is provided in the inner ring. In both cases, the piston moves parallel to the bearing rotation axis, and the top of the piston does not include the piston, i.e., the flat surface of the outer ring contacts the surface vertically and uniformly, generating a frictional force and causing the relative relationship between the inner ring and the outer ring. Stop or hold the rotary motion. Similarly, as shown in FIG. 8, two pistons may be provided in the inner ring.

If the bearing is considered from the viewpoint of a fixed wheel and a rotating wheel, the piston may be installed either. What is necessary is just to select suitably in which ring | wheels a piston is installed according to the relationship with another structure, and the supply method of a working fluid.
Of course, a piston may be provided in each of the inner and outer rings, such as a combination of the embodiments of FIGS. 3 and 7, and a combination of the embodiments of FIGS. 4 and 6. Care must be taken because both rotating wheels must be supplied with working fluid.

  Examples of different locking portions are shown in FIG. A plurality of protruding locking portions 15b are provided in the circumferential direction on the bottom surface of the hole, and the piston is provided with a plurality of holes 16b to be fitted therewith. The protruding locking portion 15b may have any shape as long as it has the same shape as the hole 16b to be fitted, such as a cylinder or a square column. Moreover, you may provide the hole which engages with the latching | locking part which protruded conversely on the piston side in the hole bottom face. In this example, the protruding locking portion 15b is a separate part from the outer ring 2, that is, the bearing, but the locking portion 15b protruding integrally may be formed on the outer ring 2.

The piston that has been described so far has been a so-called single-acting type that moves only in one direction, but it can also be a so-called double-acting type that moves in two directions. .
Two seals 11 are attached to the piston 8 to stop bidirectional fluid flow. The seal 11 is an O-ring, but other seal members may be used. The seal 11 may be attached to the outer ring side as shown in FIG. The two covers 18 are also annular, and are fitted with seals 19 and 20 so as not to leak fluid to the outside. The seal 19 may be provided on the outer ring itself, and the seal 20 may be provided on the piston 8. These seals are O-rings, but other seal members may be used. The bolts that fix the cover 18 to the outer ring 2 are not shown.
The shape and position of the port 21 and the cover 18 are considered so that the fluid from the port 21 exerts pressure on the piston upper surface 22 even when the piston is farthest from the bottom surface of the hole.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIG.
The friction material 23 is a material used for so-called brakes and clutches made of fiber, resin, rubber, metal, etc., and is formed in an annular shape and fixed to the piston 8 and the relative surface with an adhesive. Further, two seals 24 each having a ring-shaped rubber ring sandwiched between the pistons 8 are arranged in a circumferential shape, and the space including the friction material and the mating surface is sealed.
Here, the friction material 23 is not formed in an annular shape, but may be rectangular or circular as long as it is arranged in an annular shape along the friction surface, and may be fixed by screws or caulking. The friction material 23 may be attached only to the piston or only to the relative surface.
The seal 24 may use another seal member such as an O-ring, a dust seal, or an oil seal.
According to the invention described in claim 2, since the brake torque is further amplified compared to the invention described in claim 1, and a seal is provided, a more stable effect is guaranteed.

Next, in order to solve the problem, a bearing in which a non-annular piston is provided may be used, and an embodiment thereof will be described with reference to FIGS.
As shown in FIG. 12, which is an AA cross section of FIG. 11, at least one or more non-annular pistons 8 can be seen. The shape of the piston 8 and the hole may be any shape such as a cylindrical shape or a quadrangular prism shape, but it is needless to say that a cylindrical shape is preferable for manufacturing.
Further, the holes into which these pistons 8 enter may be arranged anywhere as long as the pipeline described later permits.
In order to supply fluid to each hole provided in the outer ring 2, a pipe line in the circumferential direction is required.
In FIG. 11, the circumferential pipe line 25 is formed by forming a groove 26 in the outer ring in the circumferential direction and then covering the cover 27 later. The cover 27 may be welded or bolted using a seal.
Then, a conduit 28 from each hole to the circumferential conduit 25 is provided.
In this way, fluid such as pressurized oil from a port provided in at least one place on the outer ring applies pressure to each piston bottom surface 13 through the pipe line 28 from the circumferential pipe line 25 to each hole, and all pistons 8 has a linear motion.
A non-annular piston does not need to be provided with a locking portion compared to an annular piston. Further, if a plurality of pistons are provided, a large pressure receiving area can be secured, and the same effect as that of the annular piston can be obtained.

  In this embodiment, the non-annular piston is installed in the outer ring so as to press the upper end surface of the inner ring inside the rolling element, but in the same manner as in the embodiment of the annular piston, that is, in FIG. As shown in the figure, a non-annular piston may be provided in the outer ring so as to press the inner ring outside the rolling element, and conversely, as shown in FIGS. May be installed. Further, as shown in FIGS. 5 and 8, a non-annular piston may be provided inside and outside the rolling element.

An embodiment of the following invention will be described with reference to FIG.
The friction material 23 is made of the above-described material and is fixed to each piston with an adhesive. Further, the two seals 24 described above with all the pistons interposed therebetween are arranged in a circumferential shape, and the space including the friction material and the mating surface is sealed.
Here, the friction material 23 is formed in accordance with the shape of the top of each piston as shown in FIG. They may also be fixed with screws. The friction material 23 is meaningless, but it is not always necessary to attach it to all the pistons. The friction material 23 may be attached to the relative surface as an annular friction material, or may be attached to both the piston and the relative surface.
The seal 24 may be another seal member such as an O-ring, dust seal, or oil seal.
In the present invention, the brake torque is further amplified and the seal is provided, so that a more stable effect is ensured than the inventions described in the paragraphs 0021 and 0022 .

As an embodiment of the invention described in claim 4, two embodiments in which an elastic body is attached to the piston of the bearing described in claim 2 having a single-acting piston will be described.
The first embodiment is shown in FIG. A coil spring 29 is mounted as an elastic body in a hole formed in a plurality of holes in the piston 8. The coil spring 29 returns the piston 8 to a steady position when the flow of fluid into the port 12 stops.
The coil spring 29 can be attached to the piston regardless of whether the friction material 23 is on the piston or the relative surface. Even when the piston is not annular, the same effect can be obtained if a coil spring is similarly attached.

A second embodiment is shown in FIG. As an elastic body, a wave-like spring 30 is attached to the inside and the outside across the top of the piston 8 over the circumference. The wave spring 30 returns the piston 8 to a steady position when the flow of fluid into the port 12 stops. Also in this embodiment, the wave spring 30 can be attached to the piston regardless of whether the friction material 23 is on the piston or the relative surface.
Even in a non-annular piston, the wave spring 30 is similarly mounted so as to surround the top of the piston, but in particular when the piston is cylindrical, a coil spring or a rubber ring may be mounted instead of the wave spring 30. good.

  This embodiment shows an effect different from the example in which the coil spring 29 is mounted. In other words, in the embodiment shown in FIG. 14, when used over a long period of time, the mating surface, that is, the surface that contributes to friction is constantly rubbed and worn by the coil spring 29, resulting in a decrease in the friction area. Further, when a friction material is attached to the mating surface, the friction material is rubbed earlier, so the friction area decreases rapidly. On the other hand, in the embodiment shown in FIG. 15, the wavy spring 30 is mounted on the inner side and the outer side across the top of the piston 8, so that the wavy spring 30 does not damage the friction surface.

  In both examples, the seal 24 is disposed so that foreign matter does not enter the friction surface. However, the seal 24 on the rolling element side also functions as the seal 6 of the rolling element.

  In order to obtain a larger braking force, several inventions will be described in which annular plates are stacked in multiple layers and frictional force generated between the plates is used. The plurality of annular plates are inserted into a groove provided between the inner ring and the outer ring and alternately engaged with the inner ring and the outer ring, and are pressed from the uppermost plate to generate a frictional force between the plates. The relative rotation of the inner ring and the outer ring is stopped or the stopped state is maintained.

An embodiment of the invention described in claim 3 will be described with reference to FIG.

First, the groove 31 into which the annular plate is inserted will be described.
The groove 31 is provided between the inner ring and the outer ring. That is, one of the side walls of the groove 31 is an inner ring and the other is an outer ring. The two side walls are provided with engaging portions 32 that engage the annular plate and transmit the frictional force.
In this embodiment, in order to make the bearing compact, the groove 31 is provided on the inner ring side. However, it may be provided on the outer ring side or may be provided in the vicinity of the ball.

Next, the engaging portion 32 described above will be described.
The engaging portion 32 is provided in parallel to the rotation axis of the bearing. This is because the annular plates described later are alternately engaged from above. The cross section of the engaging portion 32 perpendicular to the bearing rotation axis is a convex square, but a saw, triangle, involute or the like may be selected.
Conversely, the engaging portion 32 may have a concave shape that fits the convex shape.
The pitch in the circumferential direction of the engaging portion 32 is appropriately selected, but may be provided discretely or continuously such as a spline or a gear. If it is provided discretely, an excessive stress may be applied near the engaging portion 32, so care must be taken.
The position and length of the engaging portion 32 in the axial direction are also appropriately determined depending on the thickness and number of plates to be inserted.

Third, the annular plate 33 will be described.
The annular plate 33 is alternately connected to the inner ring and the outer ring. Therefore, the plate 33 connected to the inner ring is provided with an engaging portion that fits the above-described engaging portion on the inner periphery, and the plate 33 connected to the outer ring is similarly provided with an engaging portion on the outer periphery. Yes. The material of the plate 33 connected to the inner ring and the plate 33 connected to the outer ring is steel, but it may be preferable to change the other to a copper-based material in order to prevent adhesion. Further, the friction material as described above may be attached to either or both of the plates with screws or adhesives.

Fourth, an apparatus for pressurizing annular plates stacked in multiple layers will be described.
The device for pressurization is a single-acting annular actuator 34 having an annular piston 8. The actuator 34 includes an annular piston 8 and a body 35 having a hole in which the piston 8 is provided, and a seal 11 that seals a fluid that operates the piston, and it is only necessary to pressurize the plate. . In this embodiment, a friction material 23 is attached to the top of the piston 8, and an O-ring is used for the seal 11. This actuator is attached to the bearing body with bolts.

  The seal 6 at the upper part of the rolling element that seals the rolling element does not allow grease to be supplied to the rolling element to enter the groove 31, that is, the friction surface. The seal 6 is an O-ring, but other seals such as an oil seal and a dust seal may be used, or a seal groove may be provided on the inner ring side and attached to the inner ring.

  In the bearing configured as described above, the piston 8 is lowered by the fluid such as pressure oil or air flowing in from the port 12, and by pressing the uppermost plate of the annular plates stacked in multiple layers, a plurality of the plates 8 directly below are simultaneously pressed. A frictional force is generated between the annular plates, resulting in a huge brake torque.

In the embodiment shown in FIG. 16, a seal 24 is arranged on the circumference between the actuator and the bearing inner and outer rings opposed to the piston 8 so as to prevent foreign matter from entering between the friction surfaces. It is an Example of invention .

FIG. 17 shows an example in which the above-described pressure device, that is, the actuator is changed to a double-acting type.
In this embodiment, the single-acting piston shown in FIG. 16 is replaced with a double-acting piston as shown in FIG. Also in this case, a locking portion for transmitting the circumferential force is not necessary and is not provided. Since the structure and operation including the double-acting piston 8 have been described before, the description thereof will be omitted because it is redundant. An O-ring is attached to the inner and outer rings as a seal 24 so as to prevent foreign matter from entering the space including the groove.

An embodiment of the following invention is shown in FIG. In the pressurizing device of this embodiment, the single-acting actuator described in FIG. 16 is installed in a hole in which a plurality of coil springs 29 are formed in the piston 8, and thus the subsequent description is omitted. .
Further, as described previously, the wave spring 30 may be mounted around the top of the piston 8.

An embodiment of the following invention is shown in FIG. The pressure device of this embodiment is the same as the pressure portion of the bearing shown in FIG. That is, the pressurizing device is a single-acting actuator having at least one non-annular piston. Therefore, the piston group as shown in FIG. 12 can be seen from the AA cross section of FIG. Since the configuration including these pistons is the same as that of the third aspect of the invention, description thereof will be omitted. Although this embodiment is a single-acting type, it can also be a double-acting type.

Examples of the following invention will be described. This invention also differs from the invention described so far only in the pressurizing device.
This pressurizing apparatus is different from any of the conventional pressurizing apparatuses in that the fluid directly acts on the annular plate.

An embodiment will be described with reference to FIG. The structure of the pressurizing device is the simplest, and is composed of an annular body 35 and a seal 36. The seal 36 is an O-ring, but other seals such as an oil seal may be used.
The seal 6 at the upper part of the rolling element is entrusted with the role of sealing the rolling element, and at the same time, seals the groove 31 in which the fluid pressure acts. This seal is also an O-ring, but other seals such as an oil seal may be used.
When fluid is supplied from the port 12, the annular plate is pressurized. When oil is used as the fluid, the pressure oil fills the groove and the annular plate is pressurized.

In this case, the seal 6 directly above the rolling element may be omitted, and the pressure oil may be sealed with the seal 6 below the rolling element. Then, the rolling elements can be lubricated. However, when oil is used for the fluid, care should be taken as the coefficient of friction decreases.
When air is used as the fluid, since the rolling elements are lubricated as described above, the seal 6 directly above the rolling elements is necessary.

An embodiment of the following invention will be described with reference to FIG. The coil spring 29 is inserted into a plurality of holes formed in the piston 8 and normally urges the piston. As a result, the piston presses the annular plate, and the outer ring and the inner ring are fixed by the frictional force generated between the plates. . When it is desired to release the frictional force, fluid is introduced from the port 21 and the piston 8 is raised against the restoring force and urging force of the coil spring 29. Seals 19 and 20 are attached to the cover 18 to seal the working fluid. Further, an O-ring 24 is attached to the inner and outer rings as a seal so that foreign matter does not enter the space including the groove.
In this embodiment, since the spring is a pressurizing source, it is difficult to generate a large frictional force. Therefore, it is applied when not much braking force is required.

In a structure having a rotating part such as a machining machine, a construction machine, a robot, etc., it may be used when it is desired to firmly hold the stopped state of the rotating part.

It is sectional drawing of the conventional bearing. It is principal part sectional drawing of Example 1 of the invention of Claim 1. FIG. 3 is a sectional view taken along line AA in FIG. It is principal part sectional drawing of Example 2 of the Example of invention of Claim 1. FIG. 5 is a cross-sectional view of a main part of Embodiment 3 of the invention of claim 1. FIG. 6 is a cross-sectional view of the essential part of Embodiment 4 of the invention of claim 1. FIG. 6 is a cross-sectional view of a main part of Embodiment 5 of the invention of claim 1. It is principal part sectional drawing of Example 6 of the invention of Claim 1. It is principal part sectional drawing of Example 7 of the invention of Claim 1. FIG. 3 is a cross-sectional view of a main part of an embodiment of the invention of claim 2. FIG. 5 is a cross-sectional view of a main part of an embodiment of the invention of claim 3. FIG. 12 is a sectional view taken along line AA in FIG. FIG. 5 is a cross-sectional view of a main part of an embodiment of the invention of claim 4. FIG. 6 is a cross-sectional view of the essential part of Example 1 of the invention of claim 5. FIG. 6 is a cross-sectional view of a main part of Embodiment 2 of the invention of claim 5. FIG. 7 is a cross-sectional view of the essential part of Embodiment 1 of the invention of claim 7. FIG. 7 is a cross-sectional view of a main part of Embodiment 2 of the invention of claim 7. FIG. 9 is a cross-sectional view of a main part of an embodiment of the invention of claim 8. FIG. 10 is a cross-sectional view of main parts of an embodiment of the invention of claim 9. FIG. 11 is a cross-sectional view of a main part of an embodiment of the invention of claim 10. FIG. 14 is a cross-sectional view of main parts of an embodiment of the invention of claim 11.

1 Conventional bearing
2 Outer ring
3 Inner ring
4 Rolling elements
5 Bolt hole
6, 11, 19, 20, 24, 36 seals
7 Gear
8 piston
9 holes
10 Seal groove
12, 21 ports
13 Piston bottom
14 Piston top
15a, 15b Hole locking part
16a, 16b Piston locking part
17 collar
18, 27 cover
22 Piston top
23 Friction material
25 Circumferential pipes
26, 31 groove
28 Pipe lines to each hall
29 Coil spring
30 Wavy spring
32 Engagement part
33 Annular plate
34 Actuator
35 body

Claims (5)

In a bearing in which an inner ring and an outer ring are coaxially arranged and a rolling element is sandwiched between the inner ring and the outer ring, an annular piston is built in the outer ring, and a circumferential force is transmitted between the piston and the piston. An annular groove having an engaging portion that prohibits movement in the circumferential direction is provided, and the piston has a portion that fits with the engaging portion of the annular groove, and when the piston moves on the same axis, the piston is flat. A bearing characterized in that a top portion presses the inner ring against a surface to suppress relative rotation with the inner and outer rings. The bearing according to claim 1, wherein a friction material is attached to the piston or an inner ring surface that is in pressure contact with the top of the piston, or both, and a foreign material is attached to the friction surface between the piston and the inner ring surface that is in pressure contact with the top. A bearing with a seal attached to prevent intrusion. The bearing according to claim 1, wherein the top of the annular piston is in pressure contact with the inner ring.
An annular second groove on the same axis is provided between the inner ring and the outer ring, and an annular plate and a circumferential surface are respectively provided on the inner ring side and the outer ring side wall facing the annular second groove. Forming an engagement portion that transmits a force in a direction and prohibits the annular plate from moving in the circumferential direction, and an annular plate that fits with the engagement portion provided on the side wall on the inner ring side, The annular plate fitted to the engaging portion provided on the side wall on the outer ring side is alternately inserted into the annular second groove, and the uppermost plate is pressed against the surface to suppress relative rotation with the inner and outer rings. A bearing characterized by.   The bearing according to any one of claims 1 to 3, wherein when an inflow of fluid that press-contacts the top of the piston to the inner ring or the annular plate stops, the elastic body that biases the press-contacted piston away from the piston is provided. A bearing that is mounted between a piston and a surface to which it is pressed. 3. The bearing according to claim 1, wherein the annular piston is built in the inner ring, not the outer ring, and a top portion thereof presses against the outer ring to suppress relative rotation with the inner and outer rings. Bearing.

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