JP5911697B2 - Parallel link mechanism, constant velocity universal joint, and link actuator - Google Patents

Description

  The present invention relates to a parallel link mechanism capable of operating in a precise and wide range of operation in a three-dimensional space, and a constant velocity universal joint and a link operating device each including the parallel link mechanism and used in medical equipment, industrial equipment, and the like.

  An example of a working device having a parallel link mechanism is disclosed in Patent Document 1, an example of a constant velocity universal joint that transmits power between two axes is disclosed in Patent Document 2, and an example of a link operating device used in medical equipment, industrial equipment, and the like. Are disclosed in Patent Document 3, respectively.

JP 2000-94245 A JP 2002-349593 A US Pat. No. 5,893,296

  Since the parallel link mechanism of Patent Document 1 has a small operating angle of each link, it is necessary to increase the link length in order to set a large operating range of the traveling plate. Thereby, there existed a problem that the dimension of the whole mechanism became large and an apparatus became large. Further, when the link length is increased, the rigidity of the entire mechanism is reduced. For this reason, there is a problem that the weight of the tool mounted on the traveling plate, that is, the transportable weight of the traveling plate is limited to a small one. For these reasons, it is difficult to use in a medical device or the like that requires a precise and wide range of operation while having a compact configuration.

  The constant velocity universal joint of Patent Document 2 and the link operating device of Patent Document 3 are a parallel link mechanism provided with three or more sets of three-joint link mechanisms. Power transmission and precise operation are possible. However, if the rotation pair of each link mechanism is increased in size in order to increase the rigidity of the entire mechanism, there is a problem that interference between the members of the link mechanism is likely to occur and the operating range is narrowed. Moreover, in order to avoid interference between each member of a link mechanism, the length of the link of a link mechanism must be lengthened, and there existed a problem that the dimension of the whole mechanism will become large.

An object of the present invention is to provide a parallel link mechanism that is capable of high-speed operation in a precise and wide range of operation and that is light in weight and compact.
Another object of the present invention is to maintain the input shaft and the output shaft rotating at a constant speed even when the fold angle between the central shaft of the proximal-side link hub and the central shaft of the distal-side link hub changes. To provide a constant velocity universal joint that is precise and capable of high-speed operation in a wide range of operation, and that is lightweight and compact as a whole.
Another object of the present invention is that the distal end side link hub can be changed to an arbitrary posture with respect to the proximal end side link hub, and high speed operation in a precise and wide range of operation is possible, and the whole is lightweight. And providing a compact link actuator.

Parallel link mechanism of the present invention, the distal end side link hub relative to the proximal end side of the link hub is changed coupled posture through the three or more sets of link mechanisms, each linkage, each of said proximal end The end link member on the base end side and the tip end side that are rotatably connected to the link hub on the side and the tip end link hub, and the other end of the end link member on the base end side and the tip end side are rotated. It is a three-joint chain structure having four rotating pairs, which are formed by central link members that are connected to each other. Each of the link mechanisms has a geometric model in which the link mechanism is expressed by a straight line in which the proximal end portion and the distal end portion are symmetrical with respect to the central portion of the central link member. In the parallel link mechanism of the present invention, in the above configuration, each pair of rotating members of each of the link mechanisms has a pair of paired members connected to each other via a bearing, and a shaft portion provided on one of the paired members has a shaft portion. The annular inner surface forming part fitted to the inner periphery of the inner ring of the bearing and provided on the other pair of components is fitted to the outer periphery of the outer ring of the bearing, and the shaft part and the annular inner surface forming part are A seal structure that regulates the entry and exit of lubricant between the inside and outside of the bearing is constructed .

  According to this configuration, the proximal-side link hub, the distal-side link hub, and three or more sets of link mechanisms allow the distal-side link hub to move in two orthogonal directions relative to the proximal-side link hub. A two-degree-of-freedom mechanism is configured. In other words, it is a mechanism in which the position of the link hub on the distal end side is freely changeable with two degrees of freedom relative to the link hub on the proximal end side. Although this two-degree-of-freedom mechanism is compact, the movable range of the distal end side link hub relative to the proximal end side link hub can be widened. For example, the bending angle between the central axis of the proximal-side link hub and the central axis of the distal-side link hub is about ± 90 ° at the maximum, and the turning angle of the distal-side link hub with respect to the proximal-side link hub is set to 0. It can be set in the range of ° to 360 °.

  Further, by interposing a bearing in each rotating pair, it is possible to reduce the frictional resistance by suppressing the frictional resistance at each rotating pair, and to ensure smooth power transmission and improve durability. The seal structure constructed by the shaft provided on one of the pair members of the rotating pair and the annular inner surface forming portion provided on the other member of the pair, allows the lubricant to enter and exit between the inside and outside of the bearing. Let me regulate. Thus, by constructing the seal structure with the parts constituting the parallel link mechanism, it is not necessary to provide a seal made of a separate member, and the width of the bearing can be suppressed. Therefore, interference between the components of the link mechanism hardly occurs and the work range is widened. In addition, since the dimensions around the bearing are reduced, the entire parallel link mechanism can be reduced in weight and size.

Before Symbol seal structure includes a part of the outer peripheral surface of the shaft portion, in which constructed by a gap between the part of the inner peripheral surface of the annular inner surface forming part.
The narrower the gap, the higher the effect of preventing the lubricant inside the bearing from leaking to the outside and preventing foreign matter from entering the bearing from the outside. The shaft portion and the annular inner surface forming portion are portions around the bearing in the pair of paired members, and are always necessary when a bearing is provided in the rotating paired portion. Therefore, a seal structure can be constructed without installing another member.

In the above configuration , a part of the shaft portion is a stepped portion having an outer diameter larger than a portion fitted to the inner periphery of the inner ring of the bearing, and the end surface of the inner ring is brought into contact with the stepped surface of the stepped portion. for positioning of the inner ring in the axial direction.
The step portion of the shaft portion is necessary for positioning the inner ring of the bearing, and is a portion where the distance from the inner peripheral surface is close to a part of the annular inner surface forming portion. By utilizing the step portion of the shaft portion, a seal structure with a gap can be easily constructed without installing another member.

Further, a portion of the annular inner surface forming part has an inner diameter than the outer periphery fitted portion of the outer ring of the bearing is small stepped portion, is brought into contact with an end face of the outer ring on the stepped surface of the stepped portion outer ring Position in the axial direction .
The step portion of the annular inner surface forming portion is necessary for positioning and fixing the outer ring of the bearing, and is a portion that is close to a part of the outer peripheral surface of the shaft portion. By utilizing the step portion of the annular inner surface forming portion, a seal structure with a gap can be easily constructed without installing another member.

In the present invention, before Symbol opposite side in the axial direction from the place where it has been positioned by the step portion of the shaft portion of the bearing, an inner ring fixing means for fixing the axial position of said inner ring, said the inner ring fixing means bearing A spacer member interposed between the inner ring and the inner ring is provided , and the spacer member and the annular inner surface forming portion are used to construct a seal structure that regulates the entry and exit of lubricant between the inside and the outside of the bearing. Also good.
Generally, a spacer member is provided between the inner ring fixing means and the inner ring so that a load is uniformly applied to the inner ring. By utilizing this spacer member, a seal structure with a gap can be easily constructed without installing another member. In addition, it is difficult to build a seal structure at both ends of the bearing with only the shaft portion and the annular inner surface forming portion due to problems such as assemblability, but by using a seal structure with a spacer member and an annular inner surface forming portion in combination, The seal structure can be easily constructed.

In the case of the above configuration, the seal structure may be constructed by a gap between a part of the outer peripheral surface of the spacer member and a part of the inner peripheral surface of the annular inner surface forming portion.
The narrower the gap, the higher the effect of preventing the lubricant inside the bearing from leaking to the outside and preventing foreign matter from entering the bearing from the outside. Since the spacer member is a member around the bearing, and the annular inner surface forming portion is a portion around the bearing in one of the paired members, it can be easily used for constructing a seal structure.

A part of the annular inner surface forming part may be an outer ring fitting part having an inner diameter equal to the outer diameter of the outer ring of the bearing, and the outer ring may be fitted to the outer ring fitting part.
By making a part of the annular inner surface forming portion an outer ring fitting portion whose inner diameter is equal to the outer diameter of the outer ring of the bearing, the outer ring of the bearing can be fitted to the annular inner surface forming portion without using a separate member.

Further, a part of the annular inner surface forming portion is a stepped portion having an inner diameter smaller than a portion fitted to the outer periphery of the outer ring of the bearing, and the stepped surface of the stepped portion is brought into contact with the end surface of the outer ring to It is good to position in the axial direction.
The step portion of the annular inner surface forming portion is necessary for positioning and fixing the outer ring of the bearing, and is a portion that is close to a part of the outer peripheral surface of the spacer member. By utilizing the step portion of the annular inner surface forming portion, a seal structure with a gap can be easily constructed without installing another member.

The inner ring fixing means may be a nut that is screwed into a screw portion formed on the shaft portion.
When the inner ring fixing means is a nut, not only can the axial position of the inner ring of the bearing be fixed easily, but also the preload of the bearing can be managed by tightening torque.

In the present invention, the seal structure may be a labyrinth structure.
By adopting a labyrinth structure, it is possible to improve the sealing performance as compared with a seal structure using only a gap.

In the present invention, the annular inner surface forming portion is provided on the proximal end side end link member and the distal end side end link member, and the shaft portion is the proximal end side link hub and the distal end side link hub. And the central link member may be provided.
With this configuration, the shape of each part of the link mechanism is symmetric on the proximal end side and the distal end side. Thereby, since the seal structure of the bearing provided in each rotation pair can be made into the same structure by the base end side and the front end side, manufacturing cost can be reduced.

Alternatively, the annular inner surface forming portion is provided on the proximal end side link hub, the distal end side link hub, and the central link member, and the shaft portion is provided on the proximal end side end link member and the distal end side. It may be provided at the end link.
Also in this case, the shape of each part of the link mechanism is symmetric on the base end side and the tip end side, and the bearing seal structure provided on each rotating pair can be made the same configuration on the base end side and the tip end side, reducing the manufacturing cost it can.

In the present invention, the bearing may be an angular ball bearing.
Since the angular ball bearing is a small and highly rigid bearing, a moment load acts on the angular ball bearing, which is optimal for a bearing installed in a rotating pair portion of a parallel link mechanism that requires a compact configuration. In addition, small angular ball bearings are standard products with few seals, and it has been difficult to use them in parallel link mechanisms in the past, but small angular ball bearings are used by constructing the seal structure of the present invention. It becomes possible.

The constant velocity universal joint of the present invention is characterized in that an input shaft is provided on the link hub on the base end side and an output shaft is provided on the link hub on the tip end side in any of the parallel link mechanisms described above.
Each link mechanism of the parallel link mechanism has a geometric model in which the link model is expressed by a straight line, and the base end portion and the tip end portion are symmetrical with respect to the center portion of the center link member. Because of symmetry, the proximal link hub and proximal link member, and the distal link hub and distal link member move in the same way, and the proximal and distal rotation angles are the same. And rotate at a constant speed. For this reason, even if the bending angle of the central axis of the link hub on the proximal end side and the central axis of the link hub on the distal end side changes, the input shaft and the output shaft are maintained in a state of rotating at a constant speed.
Further, by using the parallel link mechanism that can realize the light weight and compact as described above, the constant velocity universal joint can be light and compact.

The link actuating device according to the present invention causes at least two of the three or more sets of link mechanisms in the parallel link mechanism to change the angle of at least one of the four rotation pairs. A posture change actuator is provided.
If the rotation angle of the end link member on the base end side is determined for at least two sets of the three or more link mechanisms, the attitude of the link hub on the front end side with respect to the link hub on the base end side is also determined. Therefore, by providing posture change actuators in at least two of the three or more sets of link mechanisms and appropriately controlling these posture change actuators, the link hub on the distal end side can be connected to the link hub on the proximal end side. It can be changed to any posture.
Further, by using the parallel link mechanism that can realize the light weight and compactness as described above, the light weight and compactness of the link operating device can be realized.
In the link actuating device according to the present invention, at least two sets of the three or more sets of link mechanisms may be configured such that the base end side end link member is rotated and the base end side link hub is rotated toward the front end side. A posture changing actuator that arbitrarily changes the posture of the link hub, and a speed reduction mechanism that decelerates and transmits an operation amount of the posture changing actuator to the end link member on the base end side,
The speed reduction mechanism includes a small gear that is rotated by driving the posture changing actuator, a base hub-side link hub, and a base end-side end link member that is rotatable about a rotation counter-couple shaft of the base end. It has a gear-type reduction gear portion that is meshed with a large gear provided on an end link member on the end side, and the large gear has a larger pitch circle radius than the small gear, and the pitch circle radius is From the axial center point of the rotational pair shaft of the proximal side link hub and the proximal side end link member, the axial center of the rotational pair shaft of the proximal end link member and the central link member The end on the base end side is the distance to the point projected on a plane perpendicular to the rotation pair axis of the base end side link hub and the base end side end link member and passing through its axial center point It may be longer than the arm length of the link member.

Parallel link mechanism of the present invention, the distal end side link hub relative to the proximal end side of the link hub is changed coupled posture through the three or more sets of link mechanisms, each linkage, each of said proximal end The end link member on the base end side and the tip end side that are rotatably connected to the link hub on the side and the tip end link hub, and the other end of the end link member on the base end side and the tip end side are rotated. It is a three-joint chain structure having four rotating pairs that are connected to each other, and each link mechanism has a geometric model that represents the link mechanism as a straight line with respect to the central portion of the center link member. The base end side portion and the tip end side portion have a symmetrical shape, and each rotation pair of each link mechanism has a pair of paired component members connected to each other via a bearing, The shaft portion thus fitted is fitted to the inner circumference of the inner ring of the bearing, and the annular inner surface forming portion provided on the other pair of components is fitted to the outer circumference of the outer ring of the bearing. A seal structure that restricts the entry and exit of a lubricant and the like between the inside and the outside of the bearing is constructed by the inner surface forming portion. The seal structure includes a part of the outer peripheral surface of the shaft portion and one of the annular inner surface forming portion. A part of the shaft portion is a stepped portion having a larger outer diameter than a portion fitted to the inner periphery of the inner ring of the bearing. The stepped surface of the stepped portion is in contact with the end surface of the inner ring to position the inner ring in the axial direction, and a part of the annular inner surface forming portion has a smaller inner diameter than the portion fitted to the outer periphery of the outer ring of the bearing The stepped portion is a stepped portion, and the stepped surface of the stepped portion is in contact with the end surface of the outer ring so that the axial direction of the outer ring For positioning, it can operate at high speed for precise and wide operating range, the entire mechanism can be made compact, lightweight.

  In the constant velocity universal joint according to the present invention, an input shaft is provided on the link hub on the base end side in any one of the parallel link mechanisms described above, and an output shaft is provided on the link hub on the tip end side. Even if the bend angle of the center shaft and the center shaft of the link hub on the tip side changes, the input shaft and output shaft are maintained at the same speed, and high-speed operation in a precise and wide operating range is possible. Can be lightweight and compact.

  The link actuating device according to the present invention causes at least two of the three or more sets of link mechanisms in the parallel link mechanism to change the angle of at least one of the four rotation pairs. Since the posture change actuator is provided, the distal link hub can be changed to any posture with respect to the proximal link hub, enabling high-speed operation in a precise and wide range of operation, and the overall weight is light. Can be made compact.

It is the front view which abbreviate | omitted a part of parallel link mechanism concerning one Embodiment of this invention. It is the front view which abbreviate | omitted one part which shows the different state of the parallel link mechanism. It is the perspective view which represented the parallel link mechanism three-dimensionally. It is the figure which expressed one link mechanism of the parallel link mechanism with a straight line. It is horizontal sectional drawing of the link hub etc. of the base end side of the parallel link mechanism. FIG. 6 is an enlarged view of a part of FIG. 5. FIG. 6 is an enlarged view of a different part of FIG. 5. It is the front view which abbreviate | omitted some parallel link mechanisms concerning different embodiment of this invention. It is horizontal sectional drawing of the link hub etc. of the base end side of the parallel link mechanism. FIG. 10 is an enlarged view of a part of FIG. 9. FIG. 10 is an enlarged view of a different part of FIG. 9. It is a cross section which shows the example from which a seal structure differs. It is the front view which omitted a part of constant velocity universal joint concerning one Embodiment of this invention. It is the front view which abbreviate | omitted some link actuating devices concerning one Embodiment of this invention. It is the front view which abbreviate | omitted a part of link operating device concerning different embodiment of this invention. It is a fragmentary sectional view of the link actuator. It is the elements on larger scale of FIG.

  An embodiment of a parallel link mechanism according to the present invention will be described with reference to FIGS. FIG. 1 and FIG. 2 are front views showing different states. This parallel link mechanism 1 changes the posture of the link hub 3 on the distal end side through three sets of link mechanisms 4 with respect to the link hub 2 on the proximal end side. It is connected as possible. In FIG. 1 and FIG. 2, only one set of link mechanisms 4 is shown.

  FIG. 3 is a perspective view showing the parallel link mechanism 1 three-dimensionally. Each link mechanism 4 includes a base end side end link member 5, a front end side end link member 6, and a central link member 7, and forms a three-joint link mechanism including four rotating pairs. The end link members 5 and 6 on the base end side and the front end side are L-shaped, and the base ends are rotatably connected to the link hub 2 on the base end side and the link hub 3 on the front end side, respectively. The central link member 7 is rotatably connected to the distal ends of the end link members 5 and 6 on the proximal end side and the distal end side at both ends.

  The end link members 5 and 6 on the base end side and the front end side have a spherical link structure, and the spherical link centers PA and PB (FIGS. 1 and 2) in the three sets of link mechanisms 4 coincide with each other, and the spherical surfaces thereof The distance D from the link centers PA and PB is the same. The central axis of each rotational pair of the end link members 5 and 6 and the central link member 7 may have a certain crossing angle or may be parallel.

  The three sets of link mechanisms 4 have the same geometric shape. The geometrically identical shape is a geometric model in which the link members 5, 6, and 7 are expressed by straight lines, that is, a model that is expressed by each rotation pair and a straight line connecting these rotation pairs. The base end side part and the front end side part with respect to the center part of the are said to have a symmetrical shape. FIG. 4 is a diagram representing a set of link mechanisms 4 by straight lines.

  The link mechanism 4 of this embodiment is a rotationally symmetric type, and the positions of the proximal-side link hub 2 and the proximal-side end link member 5, the distal-side link hub 3 and the distal-side end link member 6. The relationship is a position configuration that is rotationally symmetric with respect to the center line C of the central link member 7. 1 shows a state in which the central axis QA of the link hub 2 on the proximal end side and the central axis QB of the link hub 3 on the distal end side are on the same line, and FIG. 2 shows the central axis of the link hub 2 on the proximal end side. A state in which the central axis QB of the link hub 3 on the distal end side takes a predetermined operating angle with respect to QA is shown. Even if the posture of each link mechanism 4 changes, the distance D between the spherical link centers PA and PB on the proximal end side and the distal end side does not change.

  Two degrees of freedom in which the distal-side link hub 2 is movable in two orthogonal axes with respect to the proximal-side link hub 2 by the proximal-side link hub 2, the distal-side link hub 3, and the three sets of link mechanisms 4. The mechanism is configured. In other words, it is a mechanism that can freely change the posture of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side with two degrees of freedom of rotation. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side can be widened. For example, the maximum value (maximum folding angle) of the bending angle θ between the central axis QA of the link hub 2 on the proximal end side and the central axis QB of the link hub 3 on the distal end side can be set to about ± 90 °. Further, the turning angle φ of the distal end side link hub 3 with respect to the proximal end side link hub 2 can be set in a range of 0 ° to 360 °. The bending angle θ is a vertical angle in which the central axis QB of the distal end side link hub 3 is inclined with respect to the central axis QA of the proximal end side link hub 2, and the turning angle φ is the proximal end side link hub. This is a horizontal angle at which the link hub 3 on the distal end side is inclined with respect to the center axis QA.

  The link hub 2 on the base end side and the link hub 3 on the front end side have a donut shape in which a through hole 10 is formed in the center portion along the axial direction and the outer shape is a spherical shape. The proximal end link member 5 and the distal end link member 6 rotate at equal intervals in the circumferential direction of the outer peripheral surface of the proximal link hub 2 and distal link hub 3 respectively. It is connected freely.

  FIG. 5 is a horizontal sectional view of the link hub 2 and the like on the base end side, and the rotation pair portion T1 of the link hub 2 on the base end side and the end link member 5 on the base end side, and the end link on the base end side. The rotation pair T2 of the member 5 and the center link member 7 and the rotation pair T3 of the end link member 6 and the center link member 7 on the front end side are illustrated. In addition, about the rotation pair part T2, T3, only the thing of the one link mechanism 4 is shown in figure.

  In the link hub 2 on the proximal end side, communication holes 11 extending in the radial direction that connect the through hole 10 in the axial direction and the outer peripheral side are formed at three locations in the circumferential direction, and two link holes provided in each communication hole 11 are provided. The shaft member 13 is rotatably supported by the bearing 12. The outer end portion of the shaft member 13 protrudes from the link hub 2 on the proximal end side, the end link member 5 on the proximal end side is connected to the protruding portion, and a spacer member is secured by a nut 14 screwed to the distal end screw portion 13a. It is fastened together with 16. That is, in the rotating pair T1, the base end side link hub 2 which is a pair of pair constituent members and the base end side end link member 5 which is the other pair constituent members are mutually rotatable via the bearing 12. It is connected to.

  A peripheral portion of the communication hole 11 in the link hub 2 on the base end side is an annular inner surface forming portion 15 referred to in the claims. In the illustrated example, the annular inner surface forming portion 15 is a part of the link hub 2, but the annular inner surface forming portion 15 may be separated from the link hub 2. Moreover, the said shaft member 13 is a shaft part said by a claim. In the illustrated example, the shaft member 13 that is a shaft portion is a separate member from the end link member 5, but the shaft portion may be provided integrally with the end link member 5.

  More specifically, as shown in the partially enlarged view of FIG. 6, the two bearings 12 are angular ball bearings, and are arranged, for example, in a back surface combination. The inner end portion of the shaft member 13 is a stepped portion 13c having a larger outer diameter than the portion 13b fitted to the inner periphery of the inner ring 12a of the bearing 12, and the stepped surface 13d of the stepped portion 13c is the inner ring of the inner bearing 12. The inner ring 12a is positioned in the axial direction by contacting the end surface of 12a. Further, a spacer member 16 is provided between the inner ring 12a of the outer bearing 12 and the end link member 5 with both ends in contact with them. Therefore, by tightening the nut 14, the inner ring 12 a is pressed against the step surface 13 d via the end link member 5 and the spacer member 16, and the inner ring 12 a is tightened and fixed, and a preload is applied to the bearing 12. Give. The nut 14 is an inner ring fixing means for fixing the axial position of the inner ring 12a.

  A part of the annular inner surface forming portion 15 is a portion fitted to the outer periphery of the outer ring 12b of the bearing 12, that is, a step portion 15b having a smaller inner diameter than the outer ring fitting portion 15a, and the step surface 15c of the step portion 15b is on the inner side. The outer ring 12b is positioned in the axial direction by contacting the end surface of the outer ring 12b of the bearing 12. Further, the outer ring 12 b of the outer bearing 12 is prevented from coming off by a retaining ring 17 attached to the annular inner surface forming portion 15.

  The outer peripheral surface of the stepped portion 13 c of the shaft member 13 and the inner peripheral surface of the stepped portion 15 b of the annular inner surface forming portion 15 are opposed to each other through a slight gap 18. As a result, the stepped portion 13c of the shaft member 13 and the stepped portion 15b of the annular inner surface forming portion 15 can rotate with each other, but the seal structure 19 that regulates the entry and exit of the lubricant between the inside and the outside of the bearing 12 is provided. Has been built. That is, by narrowing the gap 18, the lubricant inside the bearing 12 is prevented from leaking to the outside, and foreign matters are prevented from entering the inside of the bearing 12 from the outside. The narrower the gap 18, the higher the sealing effect.

  An outer portion in the axial direction of the spacer member 16 is formed as a flange-shaped portion 16a extending to the outer diameter side while avoiding the retaining ring 17, and the outer peripheral surface of the flange-shaped portion 16a and the annular inner surface forming portion 15 are formed. A part of the outer end portion 15d is opposed to the outer end portion 15d through a slight gap 20 in a non-contact manner. As a result, the collar structure 16a of the spacer member 16 and the outer end portion 15d of the annular inner surface forming portion 15 can rotate with each other, and the seal structure 21 having the same sealing function as described above is constructed. The narrower the gap 20, the higher the sealing effect.

  In FIG. 5, the end link member 5 on the base end side and the rotation pair T <b> 2 of the center link member 7 are provided with two bearings 24 in the communication hole 23 of the center link member 7. It is the structure which supports the axial part 25 of the front-end | tip of this edge part link member 5 rotatably. That is, in the rotating pair T2, the base end side end link member 5 which is a pair of paired members and the central link member 7 which is the other paired member are rotatably connected to each other via the bearing 24. ing. The bearing 24 is fastened and fixed by a nut 27 screwed to the tip screw portion 25 a of the shaft portion 25 via a spacer member 26.

  In the case of this rotating pair portion T2, the peripheral portion of the communication hole 23 in the central link member 7 is an annular inner surface forming portion 28 referred to in the claims. In the illustrated example, the annular inner surface forming portion 28 is a part of the central link member 7, but the annular inner surface forming portion 28 may be separate from the central link member 7. In the illustrated example, the shaft portion 25 is provided integrally with the end link member 5, but the shaft portion 25 may be a separate member from the end link member 5.

  More specifically, as shown in the partially enlarged view of FIG. 7, the two bearings 24 are angular ball bearings, and are arranged in, for example, a back surface combination. The base end portion of the shaft portion 25 is a stepped portion 25c having a larger outer diameter than the portion 25b fitted to the inner periphery of the inner ring 24a of the bearing 24, and the stepped surface 25d of the stepped portion 25c is the base end side bearing 24. The inner ring 24a is positioned in the axial direction by contacting the end surface of the inner ring 24a. Further, the inner ring 24 a of the bearing 24 on the distal end side is in contact with the spacer member 26. Therefore, by tightening the nut 27, the inner ring 24a is pressed against the step surface 25d via the spacer member 26, and the inner ring 24a is fastened and fixed, and a preload is applied to the bearing 24. The nut 27 is an inner ring fixing means for fixing the axial position of the inner ring 24a.

  A part of the annular inner surface forming portion 28 is a portion fitted to the outer periphery of the outer ring 24b of the bearing 24, that is, a step portion 28b having a smaller inner diameter than the outer ring fitting portion 28a, and the step surface 28c of the step portion 28b is a base end. The outer ring 24b is positioned in the axial direction by contacting the end surface of the outer ring 24b of the side bearing 24. Further, the outer ring 24 b of the bearing 24 on the distal end side is prevented from coming off by a retaining ring 29 attached to the annular inner surface forming portion 28.

  The outer peripheral surface of the step portion 25 c of the shaft portion 25 and the inner peripheral surface of the step portion 28 b of the annular inner surface forming portion 28 are opposed to each other through a slight gap 30. As a result, the step portion 25c of the shaft portion 25 and the step portion 28b of the annular inner surface forming portion 28 can rotate with each other, but the seal structure 31 that restricts the entry and exit of the lubricant and the like between the inside and the outside of the bearing 24 is provided. Has been built. That is, by narrowing the gap 30, the lubricant inside the bearing 24 is prevented from leaking to the outside, and foreign matter is prevented from entering the inside of the bearing 24 from the outside. The narrower the gap 30, the higher the sealing effect.

  The axially distal end portion of the spacer member 26 is formed as a flange-like portion 26a extending to the outer diameter side while avoiding the retaining ring 29. The outer peripheral surface of the flange-like portion 26a and the annular inner surface forming portion 28 are formed. The front end portion 28d, which is a part of the front end, is opposed in a non-contact manner with a slight gap 32 therebetween. Thereby, the collar structure 26a of the spacer member 26 and the distal end portion 28d of the annular inner surface forming portion 28 can rotate with each other, and the seal structure 33 having the same sealing function as described above is constructed. The narrower the gap 32, the higher the sealing effect.

  The rotation pair T1 between the base end side link hub 2 and the base end side end link member 5 and the rotation end portion T2 between the base end side end link member 5 and the central link member 7 have been described above. Although the detailed description is omitted, the rotation pair T4 of the link hub 3 on the distal end side and the end link member 6 on the distal end side has the same structure as the rotation pair portion T1, and the end link member 6 on the distal end side and the center link The rotating pair portion T3 of the member 7 has the same configuration as the rotating pair portion T2.

  In this way, by using the structure in which the bearings 12 and 24 are provided in the four rotary pair portions T1 to T4 in each link mechanism 4, the frictional resistance in each rotary pair can be suppressed and the rotational resistance can be reduced. Smooth power transmission can be ensured and durability can be improved.

  In the structure in which the bearings 12 and 24 are provided, preload is applied to the bearings 12 and 24 to eliminate the radial gap and the thrust gap, thereby suppressing the rattling of the rotary pair, and the link hub 2 on the proximal end side. The rotational phase difference between the link hub 3 side on the side and the distal end side is eliminated, and the constant velocity can be maintained and the occurrence of vibration and abnormal noise can be suppressed. In particular, the backlash generated between the input and output can be reduced by setting the bearing gap between the bearings 12 and 24 to be a negative clearance.

  As the bearings 12 and 24, for example, angular ball bearings are used. Angular contact ball bearings are small and highly rigid bearings, so they are ideal for bearings 12 and 24 installed on rotating pairs T1 to T4 of the parallel link mechanism 1 where a moment load acts and a compact configuration is required. It is. In addition, small angular ball bearings are standard products with few seals, and it has been difficult to use them in parallel link mechanisms in the past, but small angular ball bearings are used by constructing the seal structure of the present invention. It becomes possible. Depending on the case, a ball bearing other than the angular ball bearing may be used, or a roller bearing may be used.

  By providing the bearing 12 embedded in the annular inner surface forming portion 15 of the link hub 2 on the proximal end side and the link hub 3 on the distal end side, the link on the proximal end side is not increased without increasing the overall outer shape of the parallel link mechanism 1. The outer shapes of the hub 2 and the link hub 3 on the distal end side can be enlarged. Therefore, it is easy to secure a mounting space for mounting the proximal-side link hub 2 and the distal-side link hub 3 to other members.

In the rotating pair portion T1 (T4) of the link hub 2 (3) and the end link member 5 (6), the end link member 5 (one of the pair members of the rotating pair is disposed on one side in the axial direction of the bearing 12. 6) and the annular inner surface forming portion 15 provided in the link hub 2 (3) which is the other pair of components, the seal structure 19 is constructed, and the shaft is provided on the other side in the axial direction. A seal structure 21 is constructed by the spacer member 16 fitted to the outer periphery of the member 13 and the annular inner surface forming portion 15.
The link hub 2 (3) and the end link member 5 (6) are parts constituting the parallel link mechanism 1. In addition, the spacer member 16 generally has an inner ring 12a and a nut 14 so that when the inner ring 12a of the bearing 12 is fastened and fixed with a nut 14 which is an inner ring fixing means, a load is uniformly applied to the inner ring 12a. It is a part provided between. In this way, by constructing the seal structures 19 and 21 with only indispensable parts, there is no need to provide a seal made of a separate member, and the width of the bearing 12 can be suppressed. Therefore, interference between the components of the link mechanism 4 hardly occurs and the work range is widened. In addition, since the dimensions around the bearing 12 are reduced, the entire parallel link 1 structure 1 can be reduced in weight and size.
Although it is difficult to construct a seal structure at both ends of the bearing 12 with only the shaft member 13 and the annular inner surface forming portion 15 due to problems such as assembly, the seal structure with the spacer member 16 and the annular inner surface forming portion 15 is used in combination. Thus, the seal structures 19 and 21 can be easily constructed at both ends of the bearing 24.

In the rotating pair T2 (T3) of the end link member 5 (6) and the central link member 7, the end link member 5 (6), which is one of the paired members of the rotating pair, is disposed on one side in the axial direction of the bearing 24. A seal structure 31 is constructed by the shaft portion 25 provided at the center and the annular inner surface forming portion 28 provided at the central link member 7 which is the other pair of components, and the outer periphery of the shaft portion 25 is provided on the other side in the axial direction. A seal structure 33 is constructed by the spacer member 26 and the annular inner surface forming portion 28 fitted to each other.
Similarly to the above, by constructing the seal structures 31 and 33 using only indispensable parts, it is not necessary to provide a seal made of another member, and the width dimension of the bearing 24 can be suppressed. Therefore, interference between the components of the link mechanism 4 hardly occurs and the work range is widened. In addition, since the dimensions around the bearing 24 are reduced, the entire parallel link 1 structure 1 can be reduced in weight and size.
Although it is difficult to construct a seal structure at both ends of the bearing 24 only by the shaft portion 25 and the annular inner surface forming portion 28 due to problems such as assemblability, the seal structure by the spacer member 26 and the annular inner surface forming portion 28 is used in combination. Thus, the seal structures 31 and 33 can be easily constructed at both ends of the bearing 24.

  More specifically, the seal structure 19 is formed by a gap 18 between the outer peripheral surface of the step portion 13 c that is a part of the shaft member 13 and the inner peripheral surface of the step portion 15 b that is a part of the annular inner surface forming portion 15. Has been built. The step portion 13c of the shaft member 13 is used for positioning the inner ring 12a, and the step portion 15b of the annular inner surface forming portion 15 is used for positioning the outer ring 12b. Since both the step portions 13c and 15b are at a distance close to each other, the seal structure 19 by the gap 18 can be easily constructed without installing another member.

  The seal structure 21 is constructed by a gap 20 between the outer peripheral surface of the flange-shaped portion 16 a that is a part of the spacer member 16 and the inner peripheral surface of the outer end portion 15 d that is a part of the annular inner surface forming portion 15. ing. The spacer member 16 is used for fastening and fixing the inner ring 12 a, and the outer end portion 15 d of the annular inner surface forming portion 15 is used for holding the retaining ring 17. A spacer 16 is provided on the spacer member 16 so that the distance between the outer peripheral surface of the collar 16a and the inner peripheral surface of the outer end portion 15d of the annular inner surface forming portion 15 is reduced. The seal structure 21 with the gap 20 can be easily constructed.

  The seal structure 31 is constructed by a gap 30 between the outer peripheral surface of the step portion 25 c that is a part of the shaft portion 25 and the inner peripheral surface of the step portion 28 b that is a part of the annular inner surface forming portion 28. . The step portion 25c of the shaft portion 25 is used for positioning the inner ring 24a, and the step portion 28b of the annular inner surface forming portion 28 is used for positioning the outer ring 24b. Since both the step portions 25c and 28b are close to each other, the seal structure 31 by the gap 30 can be easily constructed without installing another member.

  The seal structure 33 is constructed by a gap 32 between the outer peripheral surface of the flange-shaped portion 26 a that is a part of the spacer member 26 and the inner peripheral surface of the outer end portion 28 d that is a part of the annular inner surface forming portion 28. ing. The spacer member 26 is used for fastening and fixing the inner ring 24 a, and the outer end portion 28 d of the annular inner surface forming portion 28 is used for holding the retaining ring 29. A spacer 26a is provided on the spacer member 26, and the distance between the outer peripheral surface of the collar 26a and the inner peripheral surface of the outer end 28d of the annular inner surface forming portion 28 is reduced, so that another member is installed. The seal structure 33 with the gap 32 can be easily constructed.

  8 to 11 show different embodiments of the parallel link mechanism of the present invention. In this parallel link mechanism 1, the bearing 12 (FIG. 9) that rotatably supports the end link members 5 and 6 with respect to the link hub 2 on the base end side and the link hub 3 on the front end side is an outer ring rotation type. Is. The rotation pair T1 of the base end side link hub 2 and the base end side end link member 5 will be described as an example. As shown in FIG. 9, the base end side link hub 2 is provided at three locations in the circumferential direction. Shaft portions 35 are formed, and the end link member 5 is rotatably supported on the outer periphery of the shaft portions 35 via two bearings 12 provided in parallel. The two bearings 12 are provided in a communication hole 34 formed in the end link member 5, and are fastened and fixed by a nut 37 screwed to a tip screw portion 35 a of the shaft portion 35 via a spacer member 36. Yes.

  In the case of this rotating pair portion T1, the peripheral portion of the communication hole 34 in the end link member 5 is an annular inner surface forming portion 38 referred to in the claims. In the illustrated example, the annular inner surface forming portion 38 is a part of the end link member 5, but the annular inner surface forming portion 38 may be separate from the end link member 5. In the illustrated example, the shaft portion 35 is provided integrally with the link hub 2, but the shaft portion 35 may be a separate member from the link hub 2.

  More specifically, as shown in the partially enlarged view of FIG. 10, the two bearings 12 are angular ball bearings, and are arranged, for example, in combination with the back surface. The base end portion of the shaft portion 35 is a stepped portion 35c having a larger outer diameter than the portion 35b fitted to the inner periphery of the inner ring 12a of the bearing 12, and the stepped surface 35d of the stepped portion 35c is the base end side bearing 12. The inner ring 12a is positioned in the axial direction by contacting the end face of the inner ring 12a. The inner ring 12 a of the bearing 12 on the distal end side is in contact with the spacer member 36. Therefore, by tightening the nut 37, the inner ring 12a is pressed against the stepped surface 35d via the spacer member 36, and the inner ring 12a is fastened and fixed, and a preload is applied to the bearing 12. The nut 37 is an inner ring fixing means for fixing the axial position of the inner ring 12a.

  A part of the annular inner surface forming portion 38 is a portion fitted to the outer periphery of the outer ring 12b of the bearing 12, that is, a stepped portion 38b having an inner diameter smaller than that of the outer ring fitting portion 38a, and the stepped surface 38c of the stepped portion 38b is a base end. The outer ring 12b is positioned in the axial direction by contacting the end surface of the outer ring 12b of the bearing 12 on the side. Further, the end link member 5 has an annular collar portion 38d that protrudes from the side surface and has a base end that is a part of the outer ring fitting portion 38a, and the outer ring 12b is fitted into the outer ring fitting portion 38a. In the joined state, the collar portion 38d is caulked to the inner diameter side, whereby the outer ring 12b is tightly fitted, or the base end of the distal end portion 38da that is a portion protruding from the outer ring 12b of the collar portion 38d is connected to the outer ring 12b. By engaging with the end face, the outer ring 12b is positioned in the axial direction between the stepped portion 38b and the caulking portion.

  The outer peripheral surface of the stepped portion 35 c of the shaft portion 35 and the inner peripheral surface of the stepped portion 38 b of the annular inner surface forming portion 38 are opposed to each other through a slight gap 40. As a result, the stepped portion 35c of the shaft portion 35 and the stepped portion 38b of the annular inner surface forming portion 38 can rotate with each other, but the seal structure 41 that restricts the entry and exit of the lubricant between the inside and the outside of the bearing 12 is provided. Has been built. That is, by narrowing the gap 40, the lubricant inside the bearing 12 is prevented from leaking to the outside, and foreign matter is prevented from entering the inside of the bearing 12 from the outside. The narrower the gap 40, the higher the sealing effect.

  The axially distal end portion of the spacer member 36 is formed as a collar portion 36a that extends to the outer diameter side while avoiding contact with the outer ring 12a, and an outer peripheral surface and an annular inner surface forming portion of the collar portion 36a. 38 is opposed to the inner peripheral surface of the tip portion 38da which is a part of 38 in a non-contact manner through a slight gap 42. Thereby, the collar structure 36a of the spacer member 36 and the tip end portion 38da of the annular inner surface forming portion 38 can rotate with each other, and the seal structure 43 having the same sealing function as described above is constructed. The narrower the gap 42, the higher the sealing effect.

  In FIG. 9, the rotating pair T 2 of the end link member 5 and the central link member 7 on the base end side is provided with two bearings 24 in the communication hole 44 of the end link member 5, and the central link member is provided by these bearings 24. 7 is a structure that rotatably supports the shaft 45. That is, in the rotating pair T2, the base end side end link member 5 which is a pair of paired members and the central link member 7 which is the other paired member are rotatably connected to each other via the bearing 24. ing. The bearing 24 is fastened and fixed by a nut 47 screwed to the tip screw portion 45 a of the shaft portion 45 via a spacer member 46.

  A peripheral portion of the communication hole 44 in the end link member 5 on the base end side is an annular inner surface forming portion 48 referred to in the claims. In the illustrated example, the annular inner surface forming portion 48 is a part of the end link member 5, but the annular inner surface forming portion 48 may be separate from the end link member 5. In the illustrated example, the shaft portion 45 is provided integrally with the central link member 7, but the shaft portion 45 may be a separate member from the central link member 7.

  More specifically, as shown in the partially enlarged view of FIG. 11, the two bearings 24 are angular ball bearings, and are arranged, for example, in a back surface combination. The base end portion of the shaft portion 45 is a stepped portion 45c having a larger outer diameter than the portion 45b fitted to the inner periphery of the inner ring 24a of the bearing 24. The step 45c has two steps 45ca and 45cb, and the step surface 45d of the first step 45ca abuts against the end surface of the inner ring 24a of the bearing 24 on the base end side so that the inner ring 24a is moved in the axial direction. Positioning. The second step 45cb may be a separate member. For example, the second step 45cb may be a ring member, and its inner peripheral surface may be fitted and fixed to the outer peripheral surface of the first step 45ca. The inner ring 24 a of the bearing 24 on the distal end side is in contact with the spacer member 46. Therefore, by tightening the nut 47, the inner ring 24a is pressed against the step surface 45d via the spacer member 46, and the inner ring 24a is fastened and fixed, and a preload is applied to the bearing 24. The nut 47 is an inner ring fixing means for fixing the axial position of the inner ring 24a.

  A part of the annular inner surface forming part 48 is a part fitted to the outer periphery of the outer ring 24b of the bearing 24, that is, a step part 48b having an inner diameter smaller than that of the outer ring fitting part 48a. The outer ring 24b is positioned in the axial direction by contacting the end surface of the outer ring 24b of the bearing 24. Further, the end link member 5 has an annular collar portion 48d that protrudes from the side surface thereof and has a base end that is a part of the outer ring fitting portion 48a, and the outer ring 24b is fitted into the outer ring fitting portion 48a. In the joined state, the collar portion 48d is caulked to the inner diameter side, whereby the outer ring 24b is tightly fitted, or the base end of the distal end portion 48da that is a portion protruding from the outer ring 24b of the collar portion 48d is connected to the outer ring 12b. By engaging with the end face, the outer ring 24b is positioned in the axial direction between the stepped portion 48b and the caulking portion.

  The outer peripheral surface of the stepped portion 45 c of the shaft portion 45 and the inner peripheral surface of the tip end portion 48 da of the annular inner surface forming portion 48 are opposed to each other through a slight gap 50. As a result, the stepped portion 45c of the shaft portion 45 and the tip end portion 48da of the annular inner surface forming portion 48 can rotate with each other, but the seal structure 51 that restricts the entry and exit of the lubricant between the inside and the outside of the bearing 24 is provided. Has been built. That is, by narrowing the gap 50, the lubricant inside the bearing 24 is prevented from leaking to the outside, and foreign matter is prevented from entering the inside of the bearing 24 from the outside. The narrower the gap 50, the higher the sealing effect.

  The outer peripheral surface of the spacer member 46 and the inner peripheral surface of the stepped portion 48 b of the annular inner surface forming portion 48 are opposed to each other through a slight gap 52. Thereby, the spacer member 46 and the stepped portion 48b of the annular inner surface forming portion 48 can rotate with each other, and a seal structure 53 having the same sealing function as described above is constructed. The narrower the gap 52, the higher the sealing effect.

  The rotation pair T1 between the base end side link hub 2 and the base end side end link member 5 and the rotation end portion T2 between the base end side end link member 5 and the central link member 7 have been described above. Although the detailed description is omitted, the rotation pair T4 of the link hub 3 on the distal end side and the end link member 6 on the distal end side has the same structure as the rotation pair portion T1, and the end link member 6 on the distal end side and the center link The rotating pair portion T3 of the member 7 has the same configuration as the rotating pair portion T2. As described above, by using the structure in which the bearings 12 and 24 are provided in the four rotary pairs T1 to T4 in each link mechanism 4, the same operation and effect as in the case of the above embodiment can be obtained.

  FIG. 12 shows different examples of the seal structure. This seal structure is applied to the rotation pair T1 (T4) of the link hub 2 (3) and the end link member 5 (6) in the embodiment of FIGS. A plurality of grooves 55 and 56 along the circumferential direction are respectively provided on the outer peripheral surface of the portion 35 c and the outer peripheral surface of the collar-like portion 36 a of the spacer member 36. Thereby, each seal structure 57 and 58 becomes a labyrinth seal structure, and the sealing performance is further improved as compared with the seal structures 41 and 42 (FIG. 10) having only the gaps 40 and 42. This seal structure may be applied to the rotating pair T2 (T3) of the end link member 5 (6) and the central link member 7. Moreover, you may apply to each rotation pair part T1-T4 of embodiment of FIG. 1 thru | or FIG.

  FIG. 13 shows a constant velocity universal joint using the parallel link mechanism of the present invention. This constant velocity universal joint 61 has an input shaft 63 attached to the link hub 2 on the proximal end side of the parallel link mechanism 1 shown in FIGS. 1 to 7 via a mounting plate 62, and the link hub 3 on the distal end side. The output shaft 65 is attached via the attachment plate 64. The shaft centers of the input shaft 63 and the output shaft 65 coincide with the center axis QA of the link hub 2 on the base end side and the center axis QB of the link hub 3 on the base end side, respectively.

  In the parallel link mechanism 1, the angles and lengths of the shaft members 13 (FIG. 5) of the link hubs 2 and 3 on the base end side and the output side are equal, and the end link member 5 on the base end side and the end on the front end side are the same. When the geometrical shape of the central link member 6 is the same and the central link member 7 has the same shape on the proximal end side and the distal end side, the central link member 7 and the end portion with respect to the symmetry plane of the central link member 7 If the angular positional relationship with the link members 5 and 6 is the same between the proximal end side and the distal end side, the proximal end side link hub 2 and the proximal end side end link member 5 are The side link hub 3 and the distal end side end link member 6 move in the same manner. As in this example, the input shaft 63 and the output shaft 65 are provided coaxially with the central axes QA and QB on the link hubs 2 and 3 on the proximal end side and the distal end side, respectively, and rotation transmission is performed from the proximal end side to the distal end side The input shaft 63 and the output shaft 65 have the same rotation angle and rotate at a constant speed. The plane of symmetry of the central link member 7 when rotating at a constant speed is referred to as a uniform speed bisector.

  Therefore, by arranging a plurality of link mechanisms 4 having the same geometric shape sharing the base side link hub 2 and the tip side link hub 3 on the circumference, the plurality of link mechanisms 4 can move without contradiction. The central link member 7 is limited to movement only on the equal speed bisector. Thereby, even if the proximal end side and the distal end side have arbitrary operating angles, the input shaft 63 and the output shaft 65 rotate at a constant speed.

  FIG. 14 shows a link actuating device using the parallel link mechanism of the present invention. The link actuating device 71 includes a parallel link mechanism 1 shown in FIGS. 1 to 7, a base 72 that supports the parallel link mechanism 1, and two or more attitude changing actuators 73 that actuate the parallel link mechanism 1. And a controller 74 for operating the posture changing actuator 73.

  The base 72 is a vertically long member, and the link hub 2 on the base end side of the parallel link mechanism 1 is fixed to the upper surface thereof. A collar-shaped drive source mounting base 75 is provided on the outer periphery of the upper portion of the base 72, and the posture changing actuator 73 is mounted on the driving source mounting base 75 in a suspended state. The number of posture changing actuators 73 is, for example, two. The posture changing actuator 73 is a rotary actuator, and a bevel gear 76 attached to the output shaft of the posture changing actuator 73 and a fan-shaped bevel gear 77 attached to the shaft member 13 (FIG. 5) of the link hub 2 on the proximal end side are engaged with each other.

  The link actuating device 71 operates the parallel link mechanism 1 by operating the controller 74 to rotationally drive the attitude changing actuator 73. Specifically, when the posture changing actuator 73 is driven to rotate, the rotation is transmitted to the shaft member 13 via a pair of bevel gears 76 and 77, and the proximal end side link member with respect to the proximal end side link hub 2. The angle of 5 changes. Thereby, the position and posture of the link hub 3 on the distal end side are determined. The reason why the number of the link mechanisms 4 provided with the posture changing actuators 73 is two or more is that it is necessary to determine the position and posture of the distal end side link hub 3 relative to the proximal end side link hub 2. The posture changing actuators 73 may be provided in all three sets of link mechanisms 4.

  The rotational drive of the posture changing actuator 73 for operating the parallel link mechanism 1 may be manually performed by an operating tool (not shown) provided in the controller 74 or a setting device (not shown) provided in the controller 74. The control means 78 may perform automatic control so that the set amount determined by The control means 78 may be provided in the controller 74 or may be provided outside the controller 74.

  When performing automatic control, the control target value of the rotation angle βn of the end link member 5 on the proximal end side is calculated according to the attitude of the link hub 3 on the distal end side set by the setting device. The rotation angle βn means the operating position of the posture changing actuator 73. The calculation of the rotation angle βn is performed by inversely transforming Equation 1 below. Inverse conversion refers to the bending angle θ (FIG. 3) of the central axis QB of the distal end side link hub 3 with respect to the central axis QA of the proximal end side link hub 2 and the distal end side link hub 2 with respect to the proximal end side link hub 2. 3 is a conversion for calculating the rotation angle βn of the end link member 5 on the base end side from the swivel angle φ 3 (FIG. 3). In other words, the bending angle θ is a vertical angle in which the central axis QB of the distal end side link hub 3 is inclined with respect to the central axis QA of the proximal end side link hub 2, and the turning angle φ is the proximal end side link. This is a horizontal angle at which the central axis QB of the link hub 3 on the distal end side is inclined with respect to the central axis QA of the hub 2.

cos (θ / 2) sinβn−sin (θ / 2) sin (φ + δn) cosβn + sin (γ / 2) = 0 (Equation 1)
Here, γ (FIG. 3) is rotatably connected to the connecting end shaft of the central link member 7 rotatably connected to the end link member 5 on the base end side and the end link member 6 on the tip end side. This is an angle formed with the connecting end axis of the central link member 7. δn (δ1, δ2, δ3 in FIG. 3) is a circumferential separation angle of each base end side end link member 5 with respect to the base end side end link member 5 serving as a reference.

  If the control target value of the rotation angle βn is calculated, the posture detection unit 79 detects the posture of the link hub 3 on the distal end side by using two posture change actuators 73 so that the rotation angle βn becomes the control target value. Feedback control is performed using signals. The posture detection means 79 detects the rotation angle βn (β1, β2 in FIG. 3) of the proximal end side end link member 5 as shown in the figure, for example. The bending angle θ, the turning angle φ, and the rotation angle βn are mutually related, and the other value can be derived from one value.

  In this way, by controlling the rotational drive of the two attitude changing actuators 73, the position and attitude of the distal link hub 3 with respect to the proximal link hub 2 are determined. Since the posture changing actuator 73 is provided only in the two sets of the link mechanisms 4 out of the three sets of link mechanisms 4, only the two posture changing actuators 73 need be controlled. Compared with the case where the posture changing actuator 73 is provided in all the three sets of link mechanisms 4, the posture changing actuator 73 can be operated smoothly, and the operation speed is high.

  15 to 17 show different link actuating devices using the parallel link mechanism of the present invention. In FIG. 15, this link actuating device 81 is connected to a base 82 through a parallel link mechanism 1 shown in FIG. 8 to FIG. Is. A spacer 84 is interposed between the base 82 and the link hub 2 on the base end side of the parallel link mechanism 1.

  As shown in FIG. 16 and FIG. 17 which is a partially enlarged view thereof, at least two of the three sets of link mechanisms 4 of the parallel link mechanism 1 are rotated so that the base end side end link member 5 is rotated. A posture changing actuator 90 for arbitrarily changing the posture of the distal link hub 3 with respect to the end link hub 2, and the operation amount of the posture changing actuator 90 to the proximal end link member 5 is decelerated. And a speed reduction mechanism 91 for transmitting. In the illustrated example, the posture changing actuator 90 and the speed reduction mechanism 91 are provided in all of the three sets of link mechanisms 4.

  The posture changing actuator 90 is a rotary actuator, more specifically, a servo motor with a speed reducer 90 a, and is fixed to the base 82 by a motor fixing member 92. The speed reducing mechanism 91 includes a speed reducer 90 a of the posture changing actuator 90 and a gear type speed reducing portion 93.

  The gear-type speed reducing unit 93 is fixed to the small gear 96 connected to the output shaft 90b of the attitude changing actuator 90 via a coupling 95 so as to be able to transmit the rotation, and the end link member 5 on the base end side. A large gear 97 that meshes with the gear 96 is formed. In the illustrated example, the small gear 96 and the large gear 97 are spur gears, and the large gear 97 is a sector gear in which teeth are formed only on the circumferential surface of the sector. The large gear 97 has a larger pitch circle radius than the small gear 96, and the rotation of the output shaft 90 b of the attitude changing actuator 90 moves to the proximal end side link member 5 and the proximal end side link hub 2 and the proximal end side link member 5. The rotation is reduced and transmitted to the rotation around the rotation axis O <b> 1 of the rotation pair with the end link member 5. The reduction ratio is 10 or more.

  The pitch circle radius of the large gear 97 is set to be 1/2 or more of the arm length L of the end link member 5 on the base end side. The arm length L is determined from the axial center point P1 of the central axis O1 of the rotational pair of the base end side link hub 2 and the base end side end link member 5 to the base end side end link member 5 and the center. An axial center point P1 of the axial center point P2 of the center axis O2 of the rotational pair with the link member 7 is orthogonal to the rotational pair axis O1 of the base end side link hub 2 and the base end side end link member 5. The distance to the point P3 projected on the plane passing through. In the case of this embodiment, the pitch circle radius of the large gear 97 is not less than the arm length L. Therefore, it is advantageous to obtain a high reduction ratio.

  The small gear 96 has shaft portions 96 b projecting on both sides of a tooth portion 96 a meshing with the large gear 97, and both shaft portions 96 b are two bearings provided on the rotation support member 99 installed on the base 82. 100 are rotatably supported by each. The bearing 100 is a ball bearing such as a deep groove ball bearing or an angular ball bearing. In addition to arranging ball bearings in double rows as in the illustrated example, roller bearings or sliding bearings may be used. A shim (not shown) is provided between the outer rings (not shown) of the two bearings 100, and a preload is applied to the bearing 100 by tightening a nut 101 screwed to the shaft portion 96b. The outer ring of the bearing 100 is press-fitted into the rotation support member 99.

  In the case of this embodiment, the large gear 97 is a separate member from the base end side end link member 5, and is detachably attached to the base end side end link member 5 by a coupler 102 such as a bolt. ing. The large gear 97 may be integrated with the end link member 5 on the base end side.

  The rotation axis O3 of the attitude changing actuator 90 and the rotation axis O4 of the small gear 96 are located on the same axis. These rotational axes O3 and O4 are parallel to the rotational pair O1 of the base end side link hub 2 and the base end side end link member 5, and have the same height from the base 82.

  As shown in FIG. 16, each posture changing actuator 90 is controlled by the control device 110. The control device 110 is of a numerical control type by a computer, and includes a posture setting means 111 for setting a posture of the distal end side link hub 3 with respect to the proximal end side link hub 2 and a distal end side with respect to the proximal end side link hub 2. An output command is given to each posture changing actuator 90 based on a signal from the posture detecting means 112 for detecting the posture of the link hub 3. The posture setting means 111 sets the posture of the link hub 3 on the distal end side by defining, for example, a bending angle θ (see FIG. 3) and a turning angle φ (see FIG. 3). The posture detection means 112 detects the rotation angle βn (β1, β2 in FIG. 3) of the proximal end side end link member 5 with an encoder (not shown), for example. Alternatively, an encoder (not shown) of the attitude changing actuator 90 may be used for detecting the attitude of the link hub 3 on the distal end side. The bending angle θ, the turning angle φ, and each rotation angle βn are mutually related, and the other value can be derived from one value.

  When the posture of the distal end side link hub 3 is changed with respect to the proximal end side link hub 2, the proximal end side end link member 5 is changed according to the posture of the distal end side link hub 3 set by the posture setting means 111. The control target value of the rotation angle βn is calculated. The rotation angle βn means the operating position of the attitude changing actuator 90. The calculation of the rotation angle βn is performed by inversely transforming the equation 1. Inverse conversion is conversion for calculating the rotation angle βn of the end link member 5 on the base end side from the bending angle θ and the turning angle φ.

  When the control target value of the rotation angle βn is calculated, the output of each posture changing actuator 90 is controlled by feedback control using the signal of the posture detection means 112 so that the actual rotation angle βn becomes the control target value. As a result, the end link members 5 on the base end side of all the link mechanisms 4 are rotated by a predetermined rotation angle βn, and the link hub 2 on the front end side is changed to the posture set by the posture setting means 111.

  Although this link actuating device 81 is compact, the movable range of the link hub 3 on the distal end side can be widened with respect to the link hub 2 on the proximal end side, so that the operability of a medical instrument attached to the distal end attachment member 83 is improved. Is good. By providing the posture change actuator 90 and the speed reduction mechanism 91 in all of the three sets of link mechanisms 4, no matter what posture the link hub 3 on the distal end side is in relation to the link hub 2 on the proximal end side. It can be driven with good balance. That is, the driving force balance is good. Accordingly, each posture changing actuator 90 can be reduced in size. Further, by providing the posture change actuator 90 and the speed reduction mechanism 91 in all of the three sets of link mechanisms 4, it is possible to control the backlash of the parallel link mechanism 1 and the speed reduction mechanism 91 so that the link on the tip side is reduced. The positioning accuracy of the hub 3 can be improved, and the link actuator 81 itself can be made highly rigid.

  The gear type reduction unit 93 of the reduction mechanism 91 is a combination of a small gear 96 and a large gear 97, and a high reduction ratio of 10 or more can be obtained. If the reduction ratio is high, the positioning resolution of the encoder or the like is increased, so that the positioning resolution of the link hub 3 on the distal end side is improved. Further, a low output posture changing actuator 90 can be used. In this embodiment, the posture changing actuator 90 with the reduction gear 90a is used. However, if the reduction ratio of the gear-type reduction gear 93 is high, the posture changing actuator 90 without the reduction gear can be used. The posture changing actuator 90 can be reduced in size.

By setting the pitch circle radius of the large gear 97 to ½ or more of the arm length L of the end link member 5 on the base end side, the bending moment of the end link member 5 on the base end side due to the tip load is reduced. . Therefore, it is not necessary to increase the rigidity of the entire link actuator 81 more than necessary, and the weight of the end link member 5 on the base end side can be reduced. For example, the end link member 5 on the base end side can be changed from stainless steel (SUS) to aluminum. Further, since the pitch circle radius of the large gear 97 is relatively large, the surface pressure of the tooth portion of the large gear 97 is reduced, and the rigidity of the entire link actuator 81 is increased.
Further, when the pitch circle radius of the large gear 97 is equal to or greater than ½ of the arm length, the large gear 97 is installed at the rotating pair of the link hub 2 on the base end side and the end link member 5 on the base end side. Since the diameter of the bearing 12 is sufficiently larger than the outer diameter of the bearing 12, a space is created between the teeth of the large gear 97 and the bearing 12, and the large gear 97 can be easily installed.

  Particularly in the case of this embodiment, the pitch circle radius of the large gear 97 is equal to or greater than the arm length L, so that the pitch circle radius of the large gear 97 is further increased, and the above-mentioned actions and effects appear more remarkably. In addition, the small gear 96 can be installed on the outer diameter side of the link mechanism 4. As a result, an installation space for the small gear 96 can be easily secured, and the degree of freedom in design increases. Further, interference between the small gear 96 and other members is difficult to occur, and the movable range of the link operating device 81 is widened.

  Since the small gear 96 and the large gear 97 are spur gears, they are easy to manufacture and have high rotation transmission efficiency. Since the small gear 96 is supported by the bearings 100 on both sides in the axial direction, the support rigidity of the small gear 96 is high. As a result, the angle holding rigidity of the end link member 5 on the base end side due to the distal end load is increased, and the rigidity and positioning accuracy of the link actuator 81 are improved. Further, the rotation axis O3 of the attitude changing actuator 90, the rotation axis O4 of the small gear 96, and the central axis O1 of the rotation pair of the base end side link hub 2 and the base end side end link member 5 are the same. Since it is on a flat surface, the overall balance is good and the assemblability is good.

  Since the large gear 97 is detachably attached to the end-side end link member 5, the reduction ratio of the gear-type reduction portion 93 and the operation of the front-end side link hub 3 with respect to the base-end side link hub 2. It becomes easy to change the specifications such as the range, and the mass productivity of the link actuator 81 is improved. That is, the same link actuating device 81 can be applied to various uses only by changing the large gear 97. Also, maintainability is good. For example, when a failure occurs in the gear-type speed reducing unit 93, it is possible to cope with the problem by replacing only the speed reducing unit 93.

DESCRIPTION OF SYMBOLS 1 ... Parallel link mechanism 2 ... Base end side link hub 3 ... Front end side link hub 4 ... Link mechanism 5 ... Base end side end link member 6 ... Front end side end link member 7 ... Central link member 12, 24 ... Bearings 12a, 24a ... Inner rings 12b, 24b ... Outer rings 13 ... Shaft members (shaft portions)
13a, 25a, 35a, 45a ... Screw portions 13c, 25c, 35c, 45c ... Step portions 13d, 25d, 35d ... Step surfaces 14, 27, 37, 47 ... Nuts (inner ring fixing means)
15, 28, 38, 48 ... annular inner surface forming portions 15a, 28a, 38a, 48a ... outer ring fitting portions 15b, 28b, 38b, 48b ... step portions 15c, 28c, 38c, 48c ... step surfaces 16, 26, 36, 46 ... spacer members 18, 20, 30, 32, 40, 42, 50, 52 ... gaps 19, 21, 31, 33, 41, 43, 51, 53, 57, 58 ... seal structures 25, 35, 45 ... Shaft 61 ... Constant velocity universal joint 63 ... Input shaft 65 ... Output shaft 71,81 ... Link actuator 73,90 ... Attitude changing actuators T1, T2, T3, T4 ... Rotating pair QA ... Base end side link hub Center axis QB ... Center axis of the link hub on the tip side

Claims (13)

The distal end side link hub to link hub of the base end side, is changed coupled posture through the three or more sets of link mechanisms, each linkage, respectively link hub and the distal end of the proximal-side An end link member on the base end side and the tip end side, one end of which is rotatably connected to the link hub, and a central link member which rotatably connects the other end of the end link member on the base end side and the tip end side, respectively Each of the link mechanisms has a geometric model representing the link mechanism as a straight line, a proximal end portion and a distal end portion with respect to the central portion of the central link member. In the parallel link mechanism that is symmetrical with
Each rotating pair of each link mechanism has a pair of paired members connected to each other via a bearing, and a shaft portion provided on one of the paired members is fitted to the inner periphery of the inner ring of the bearing, An annular inner surface forming portion provided on the other pair of members is fitted to the outer periphery of the outer ring of the bearing, and the shaft portion and the annular inner surface forming portion allow the lubricant and the like to enter and exit between the inside and the outside of the bearing. The seal structure is constructed by a gap between a part of the outer peripheral surface of the shaft part and a part of the inner peripheral surface of the annular inner surface forming part, A part of the shaft portion is a stepped portion having an outer diameter larger than a portion fitted to the inner periphery of the inner ring of the bearing, and the stepped surface of the stepped portion is in contact with the end surface of the inner ring, thereby Positioning in a direction, and a part of the annular inner surface forming part is on the outer periphery of the outer ring of the bearing. Combined inner diameter is smaller step portion than the portion, parallel link mechanisms step surface of the step portion is positioned in the axial direction of the outer ring by abutting the end face of the outer ring. 2. The inner ring fixing means for fixing the axial position of the inner ring on the opposite side to the position positioned at the step portion of the shaft portion of the bearing, and the inner ring fixing means and the bearing according to claim 1. A spacer member interposed between the inner ring and the inner ring is formed by the spacer member and the annular inner surface forming portion, and a seal structure that restricts the entry and exit of the lubricant between the inside and the outside of the bearing is constructed, This seal structure is a parallel link mechanism constructed by a gap between a part of the outer peripheral surface of the spacer member and a part of the inner peripheral surface of the annular inner surface forming part. The distal end side link hub to link hub of the base end side, is changed coupled posture through the three or more sets of link mechanisms, each linkage, respectively link hub and the distal end of the proximal-side An end link member on the base end side and the tip end side, one end of which is rotatably connected to the link hub, and a central link member which rotatably connects the other end of the end link member on the base end side and the tip end side, respectively Each of the link mechanisms has a geometric model representing the link mechanism as a straight line, a proximal end portion and a distal end portion with respect to the central portion of the central link member. In the parallel link mechanism that is symmetrical with
Each rotating pair of each link mechanism has a pair of paired members connected to each other via a bearing, and a shaft portion provided on one of the paired members is fitted to the inner periphery of the inner ring of the bearing, An annular inner surface forming portion provided on the other pair of members is fitted to the outer periphery of the outer ring of the bearing, and the shaft portion and the annular inner surface forming portion allow the lubricant and the like to enter and exit between the inside and the outside of the bearing. The seal structure is constructed by a gap between a part of the outer peripheral surface of the shaft part and a part of the inner peripheral surface of the annular inner surface forming part, A part of the shaft portion is a stepped portion having an outer diameter larger than a portion fitted to the inner periphery of the inner ring of the bearing, and the stepped surface of the stepped portion is in contact with the end surface of the inner ring, thereby Positioning in a direction, and a part of the annular inner surface forming part is on the outer periphery of the outer ring of the bearing. Is a combined inner diameter is small stepped portion than the portion, and the axial positioning of the outer ring by step surface of the step portion abuts on the end surface of the outer ring,
Opposite the axial direction from the place where it has been positioned by the step portion of the shaft portion of the bearing, between the inner ring fixing means for fixing the axial position of the inner ring, the inner ring fastening means and the inner race of the bearing A spacer structure is provided that regulates the entry and exit of a lubricant and the like between the inside and the outside of the bearing by the spacer member and the annular inner surface forming portion. A parallel link mechanism constructed by a gap between a part of the outer peripheral surface of the spacer member and a part of the inner peripheral surface of the annular inner surface forming part. Oite to claim 1, opposite the axial direction of the portion which is positioned at the stepped portion of the shaft portion of the bearing, an inner ring fixing means for fixing the axial position of the inner ring of the bearing, the inner ring fixed means that the provided and spacer member interposed between the inner ring of the bearing, the seal structure by said said spacer member annular inner surface forming part, for regulating the entry and exit of lubricant or the like between the interior of the bearing and the outer This seal structure is constructed by a gap between a part of the outer peripheral surface of the spacer member and a part of the inner peripheral surface of the annular inner surface forming part,
A part of the annular inner surface forming part is an outer ring fitting part whose outer diameter is equal to the outer diameter of the outer ring of the bearing, and the outer ring is fitted to the outer ring fitting part, and a part of the annular inner surface forming part is formed. Is a stepped portion having a smaller inner diameter than the portion fitted on the outer periphery of the outer ring of the bearing, and the stepped surface of the stepped portion contacts the end surface of the outer ring to position the outer ring in the axial direction. . The link hub on the distal end side is connected to the link hub on the proximal end side through three or more sets of link mechanisms so that the posture can be changed, and each link mechanism includes the link hub on the proximal end side and the link hub on the distal end side. An end link member on the base end side and the tip end side, one end of which is rotatably connected to the link hub, and a central link member which rotatably connects the other end of the end link member on the base end side and the tip end side, respectively Each of the link mechanisms has a geometric model representing the link mechanism as a straight line, a proximal end portion and a distal end portion with respect to the central portion of the central link member. In the parallel link mechanism that is symmetrical with
Each rotating pair of each link mechanism has a pair of paired members connected to each other via a bearing, and a shaft portion provided on one of the paired members is fitted to the inner periphery of the inner ring of the bearing, An annular inner surface forming portion provided on the other pair of members is fitted to the outer periphery of the outer ring of the bearing, and the shaft portion and the annular inner surface forming portion allow the lubricant and the like to enter and exit between the inside and the outside of the bearing. The seal structure is constructed by a gap between a part of the outer peripheral surface of the shaft part and a part of the inner peripheral surface of the annular inner surface forming part, A part of the shaft portion is a stepped portion having an outer diameter larger than a portion fitted to the inner periphery of the inner ring of the bearing, and the stepped surface of the stepped portion is in contact with the end surface of the inner ring, thereby Positioning in a direction, and a part of the annular inner surface forming part is on the outer periphery of the outer ring of the bearing. Is a combined inner diameter is small stepped portion than the portion, and the axial positioning of the outer ring by step surface of the step portion abuts on the end surface of the outer ring,
An inner ring fixing means for fixing an axial position of the inner ring of the bearing on a side opposite to a position positioned at the step portion of the shaft portion of the bearing, and the inner ring fixing means and the inner ring of the bearing; A spacer member is provided between the bearing member and the annular inner surface forming portion, and a seal structure that restricts the entry and exit of lubricant between the inside and the outside of the bearing is constructed by the spacer member and the annular inner surface forming portion. Is constructed by a gap between a part of the outer peripheral surface of the spacer member and a part of the inner peripheral surface of the annular inner surface forming part,
A part of the annular inner surface forming part is an outer ring fitting part whose outer diameter is equal to the outer diameter of the outer ring of the bearing, and the outer ring is fitted to the outer ring fitting part, and a part of the annular inner surface forming part is formed. Is a stepped portion having a smaller inner diameter than the portion fitted on the outer periphery of the outer ring of the bearing, and the stepped surface of the stepped portion contacts the end surface of the outer ring to position the outer ring in the axial direction. . 6. The parallel link mechanism according to claim 2 , wherein the inner ring fixing means is a nut that is screwed into a screw portion formed on the shaft portion. 7. 7. The parallel link mechanism according to claim 1 , wherein the seal structure is a labyrinth structure. Any Oite to one of claims 1 to claim 7, wherein the annular inner surface forming part provided at an end portion link members of end link member and the distal end of the proximal-side, the shaft portion is the group A parallel link mechanism provided on an end-side link hub, the tip-side link hub, and the central link member. 9. The annular inner surface forming portion according to claim 1 , wherein the annular inner surface forming portion is provided on the base end side link hub, the front end side link hub, and the central link member, and the shaft portion is the base end. A parallel link mechanism provided on the end link member on the end side and the end link on the tip end side. The parallel link mechanism according to any one of claims 1 to 9 , wherein the bearing is an angular ball bearing. It claims 1 provided the input shaft to the proximal end side link hub in the parallel link mechanism according to any one of claims 10, and this output shaft is provided on the distal end side link hub Characteristic constant velocity universal joint. The angle of at least one rotation pair of four rotation pairs in the two or more link mechanisms among the three or more sets of link mechanisms in the parallel link mechanism according to any one of claims 1 to 11. A link actuating device comprising a posture changing actuator for changing the position. 13. The link actuating device according to claim 12, wherein at least two sets of the three or more sets of link mechanisms are rotated with respect to the link hub on the base end side by rotating the end link member on the base end side. An attitude changing actuator for arbitrarily changing the attitude of the link hub on the distal end side, and a speed reducing mechanism for decelerating and transmitting the operation amount of the attitude changing actuator to the end link member on the proximal end side;
The speed reduction mechanism includes a small gear that is rotated by driving the posture changing actuator, a base hub-side link hub, and a base end-side end link member that is rotatable about a rotation counter-couple shaft of the base end. It has a gear-type reduction gear portion that is meshed with a large gear provided on an end link member on the end side, and the large gear has a larger pitch circle radius than the small gear, and the pitch circle radius is From the axial center point of the rotational pair shaft of the proximal side link hub and the proximal side end link member, the axial center of the rotational pair shaft of the proximal end link member and the central link member The end on the base end side is the distance to the point projected on a plane perpendicular to the rotation pair axis of the base end side link hub and the base end side end link member and passing through its axial center point It is longer than the arm length of the link member. The actuator is a rotary actuator, and the rotation axis of the rotary actuator and the rotation axis of the small gear are on the same axis, and these rotation axes are connected to the base end side link hub and the base end side end. A link actuator that is parallel to the rotational pair of the link member.

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