WO2004073935A1

WO2004073935A1 - Link-actuating device

Info

Publication number: WO2004073935A1
Application number: PCT/JP2004/000440
Authority: WO
Inventors: Keisuke Sone; Hiroshi Isobe
Original assignee: Ntn Corporation
Priority date: 2003-02-18
Filing date: 2004-01-20
Publication date: 2004-09-02
Also published as: JP2004261886A

Abstract

In a link-actuating device, the outline of a link hub is expanded without expanding the outline of the entire device, and a drive mechanism, such as an actuator, is compactly provided. In a link-actuating device, end portion link members are rotatably connected to each of link hubs respectively arranged at the input side and the output side, the device has three sets of link mechanisms where the input side and output side end portion link members are rotatably connected to central link members, and the input side and output side link mechanisms are geometrically the same with respect to a cross section at the center portion of each link mechanism. Bearing outer rings are enclosed in each link hub and bearing inner rings are connected to the end portion link members, and as a result, bearing structures are installed in the link hubs.

Description

Link Actuator Technical Field

The present invention relates to a link actuating device used for a link mechanism such as a parallel link mechanism or a robot joint that performs high-speed and precise operations such as complicated processing and article handling in a three-dimensional space. Background art

For example, there is a working device equipped with a parallel link mechanism that performs high-speed and precise work such as complicated processing and handling of articles in a three-dimensional space (for example, Japanese Patent Application Publication No. 2000-9244). reference).

This working device includes a parallel link mechanism that changes the position and posture of the traveling plate with respect to the base plate by cooperatively expanding and contracting a plurality of links that connect the base plate and the trapping plate. By attaching a tool to the traveling plate of this parallel link mechanism and arranging the table that holds the work rotatably, the position and orientation of the tool with respect to the work on the table can be changed freely. This enables complicated processing and handling of articles in a three-dimensional space.

In the parallel link mechanism, it is possible to reduce the mass of the movable part, and to perform complicated processing in a three-dimensional space and work such as article handling, such as the positioning error of each link is averaged at its tip. It has great features for high-speed and precise execution.

However, in the parallel link mechanism described above, since the operating angle of each link is small, if the operating range of the traveling plate is set to be large, the link length increases, and the overall size of the mechanism increases, resulting in an increase in the size of the device. There was a problem of inviting In addition, the rigidity of the entire mechanism is low, and the weight of the tool mounted on the traveling plate, that is, the payload of the traveling plate is small. There was also a problem that it was limited to things.

In order to solve this problem, the present applicant has previously proposed a link actuating device having a compact structure, a high rigidity, and a link mechanism having a large load capacity (Japanese Patent Application No. 200/1990). 2—1 7 0 2 2 3).

This link actuating device rotatably connects the end link members to the link hubs provided on the input member and the output member, and connects the end link members on the input side and the output side to the central link member. There are at least three sets of link mechanisms rotatably connected to the input mechanism, the input side and the output side are geometrically identical with respect to the cross section at the center of each link mechanism, and each link mechanism connected to the input member Of the rotating pairs, a stationary mechanism for stopping the output member at an arbitrary position is provided at one or more rotating portions of one or more pairs of two or more link mechanisms.

However, in this link actuating device, since the cross-sectional area of the central portion of the input member and the output member at the center of the link haptic is small, the mounting space of the input / output member is narrow, and the space inside the link mechanism is small. It was difficult to secure an installation space for a passage for circulating a control medium between the input member and the output member by utilizing the above. In addition, a large installation space is secured above the input member because the actuator and the rotation angle drive gear unit provided for controlling the angle of the output member are installed so as to protrude outside the link haptic of the link mechanism. There is a need to.

Furthermore, since the above-mentioned actuating unit and the rotation angle drive gear unit are exposed to the external environment, it is necessary to take measures to protect them from the outside, and the size of the device becomes large. Disclosure of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to provide a link operating device capable of enlarging the outer shape of a central portion of a link hap without increasing the outer shape of the entire device, and enabling a compact arrangement of a drive mechanism such as an actuator.

According to the present invention, an end link member is rotatably connected to a link hub provided on each of an input member and an output member, and the end link members on the input side and the output side are each used as a central link member. Has three or more sets of link mechanisms that are rotatably connected to each other. In a link operating device in which the input side and the output side are geometrically the same with respect to the cross section at the center of the mechanism, by including the bearing outer ring in the link hub and connecting the bearing inner ring to the end link member, A bearing structure is embedded in the link hub.

As a specific bearing structure, the link hub has a ring shape having a center hole in the axial direction, and a shaft member is fitted through a through hole formed in the radial direction via a bearing, and A structure in which an end link member is connected to the outer shaft end is possible.

In the present invention, the bearing outer ring is included in the link hub, and the bearing inner ring is connected to the end link member to embed the bearing structure in the link hub. The external shape can be enlarged, and the space for mounting the input / output members can be secured. Further, by expanding the link hub, the space inside the link mechanism can be used, and it becomes easy to secure an installation space for a passage for flowing the control medium between the input member and the output member.

The input member and the output member are connected by three or more sets of link mechanisms, and each link mechanism has the same geometric shape. The reason why the number of link mechanisms is three or more is to provide a mechanism having two degrees of freedom between the input member and the output member. Here, “the input side and the output side are geometrically the same with respect to the cross section at the center of the link mechanism” means that when the input side and the output side are separated on the symmetry plane of the central link member, It means that the geometrical shapes of the side and the output side are the same.

Each link mechanism constitutes a three-bar chain consisting of four rotating pairs. Each end link member on the input side and the output side has a spherical link structure, and the center of the spherical link in three or more sets of link mechanisms coincides, and the distance from the center is also the same. The rotating pair, which is a connecting portion between the end link member and the center link member, may have a certain crossing angle or may be parallel. However, the shapes of the center link members in three or more sets of link mechanisms are geometrically the same.

In the present invention, it is preferable that a rotation transmitting section is provided at an inner shaft end of the shaft member, and an actuator for controlling a rotation angle position of the end link member is coupled via the rotation transmitting section. . With this configuration, since the rotation transmitting portion can be disposed inside the shaft member of the link hub, the rotation transmitting portion can be protected. Also, -The evening can be arranged in an effective space outside the link mechanism via the rotation transmitting unit, and the device can be easily made compact. Further, if the actuating mechanism is configured to be detachable from the link mechanism, the actuating mechanism can be assembled separately from the link mechanism, thereby facilitating assembly and maintenance.

Further, in the present invention, it is preferable that a bearing structure is embedded in the central link member by including a bearing outer ring in the central link member and connecting a bearing inner ring to an end link member. As a specific bearing structure, a structure is possible in which a shaft is integrally provided at one end of the end link member, and the shaft is inserted into a through hole formed in the center link member via a bearing. is there. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing an embodiment of a link operating device according to the present invention.

FIG. 2 is a sectional view showing the link hub and the end link member of FIG.

FIG. 3 is a perspective view including a partly omitted portion showing the link hub and the actuator of FIG.

FIG. 4 is a perspective view showing another embodiment of the link operating device according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The embodiment shown in FIG. 1 is, for example, a set of three sets used for a link mechanism such as a parallel link mechanism or a robot joint for performing operations such as complicated processing and article handling in a three-dimensional space at high speed and precision. Link mechanisms 1 to 3 are provided.

Each of these three sets of link mechanisms 1 to 3 (first to third link mechanisms) has a geometrically identical shape. The input sides of the link mechanisms 1 to 3 are attached to the fixed parts of the device in which this actuator is incorporated, for example, the actuator case m, and the output sides of the link mechanisms 1 to 3 are those of the device in which the actuator is incorporated. Attached to movable parts, for example, tools.

Each of the link mechanisms 1 to 3 includes an input side end link member 1 a to 3 a, a center link member lb to 3 b, and an output side end link member 1 c to 3 c. It forms a three-bar linkage mechanism. End link members la ~ 3a, lc ~ 3c In the spherical link structure, the center of the spherical link in the three sets of link mechanisms 1 to 3 is the same, and the distance from the center is also the same. The rotating even-numbered axis serving as a connecting portion between the end link members 1a to 3a and 1c to 3c and the center link members lb to 3b may have a certain intersection angle or may be parallel. However, the shapes of the center link members 1 b to 3 b in the three sets of link mechanisms 1 to 3 are geometrically identical.

One set of link mechanisms 1-3 is composed of the input side actuator and the output side tool (not shown), two link hubs 4, 5 attached to it, and both link hubs 4, 5 The two end link members 1a to 3a and 1c to 3c rotatably connected thereto and the two end link members 1a to 3a and 1c to 3c are rotatably connected to each other. It has one central link member 1b-3b for connecting the both end link members 1a-3a, 1c-3c to each other.

The link mechanisms 1 to 3 of the embodiment of FIG. 1 are rotation target types, and the input side link hub 4 and end link members 1 a to 3 a and the output side link hub 5 and end link members 1 c to 3 The positional relationship of c is rotationally symmetric with respect to the center line A of the center link members 1b to 3b. FIG. 1 shows a state in which the link hub shaft C on the output side has a predetermined operating angle with respect to the link hap shaft B on the input side.

The link mechanisms 1 to 3 in the embodiment shown in FIG. 4 are mirror image target types. The link hap 4 and the end link members la to 3a on the input side and the link hap 5 and the end link member 5 on the output side. The positional relationship between 1 c and 3 c is mirror-symmetric with respect to the center line A of the central link members 1 b and 3 b. FIG. 4 shows a state in which the link hap shaft C on the output side has a predetermined operating angle with respect to the link hub shaft B on the input side.

FIG. 2 shows the link hub 4 arranged on the input side. The link hub 4 shown in the figure has a central hole 6 formed in the axial direction for passage of wiring and the like, and has a donut shape having a spherical outer shape so that a large angle can be obtained. It has a structure in which holes 8 are formed at equal intervals in the circumferential direction, and a shaft member 10 is inserted into the through hole 8 via a bearing 9.

The bearing 9 includes a bearing outer ring fitted in the through hole 8 of the link hub 4, a bearing inner ring fitted on the shaft member 10, a ball rotatably inserted between the bearing outer ring and the bearing inner ring, and the like. Of rolling elements. The inner end of the shaft member 10 has link mechanisms 1 to 3 described later. A gear portion 11 for transmitting power to the drive mechanism is formed.

The center hole 6 of the ring hap 4 and the inner space S of the link mechanisms 1 to 3 are effectively used as a means for securing an installation space for a passage for circulating a control medium between input and output. A bearing 9 that rotatably supports the shaft member 10 with respect to the link hub 4 is prevented from being removed from the link hub 4 by a retaining ring 12.

As the bearing 9, besides disposing two ball bearings as shown in the figure, it is also possible to use an angular ball bearing, a plain bearing or a plain bearing. The link hub 5 arranged on the output side has the same structure as the link hap 4 of FIG. 2 except that no gear portion is provided at the inner end of the shaft member 10. The positions of the shaft members 10 in the circumferential direction may not be equal, but the link happers 4 and 5 on the input side and the output side need to have the same circumferential positional relationship. The link hubs 4 and 5 are shared by three sets of link mechanisms 1 to 3, and end link members 1a to 3a and 1c to 3c are connected to each shaft member.

The end link members 1a to 3a and 1c to 3c are L-shaped, and one side is connected to the tip of a shaft member 10 protruding from the link hubs 4 and 5 with a nut 13 and the other side is connected. Connect to center link material lb ~ 3 b. The end link members 1 a to 3 a and 1 c to 3 c have a shape in which the inside of the bent base end of the shaft portion 15 located on the link center side is greatly pressed so as to take a large angle. .

The shaft member 10 and the end link members 1a to 3a and 1c to 3c can be joined by crimping in addition to the nut 13 described above. In this case, the joining structure can be reduced. Space can be realized. Furthermore, if the shaft member 10 and the end link members 1a to 3a and 1c to 3c are connected by a key or a selection, the connection structure can be prevented from loosening, and the transmission torque can be increased. You can also.

On the other hand, the center link members 1b to 3b are substantially L-shaped, and have through holes 14 on both sides. Each of the center ring members 1b to 3b has a shape in which a circumferential side surface is cut so as to take a large angle. The shaft part 15 bent integrally from the other side of the end link members 1 a to 3 a and 1 c to 3 c has through holes on both sides of the central link members 1 b to 3 b via the bearing 16. Insert 1 through 4.

This bearing 16 is provided outside the bearing fitted inside the through hole 14 of the center link member 1 b to 3 b. A ring, a bearing inner ring externally fitted to the shaft portion 15 of the end link members 1a to 3a, 1c to 3c, and a ball or the like rotatably inserted between the bearing outer ring and the bearing inner ring. It consists of moving objects. The bearing 16 that rotatably supports the center link member 1 b to 3 b with respect to the end link members 1 a to 3 a and 1 c to 3 c is a center link member lb to 3 b by a retaining ring 17. Has been locked from.

The angle formed by the through hole 8 of the link hub 4 and the through hole 14 of the central link member 3b is 90 ° from the position configuration of the rotationally symmetric link mechanism 3. The angle formed by the through-holes 14 on the input side and the output side of the center link members 1b to 3b is in a practical range of 40 ° to 100 °. This is because if the angle is smaller than 40 °, the outer diameter of the center link members 1b to 3b becomes too large, and 100. If it is larger, the central link members lb to 3b become longer in the axial direction, and the operating angle becomes smaller due to mechanical interference.

In the link mechanisms 1 to 3, the angles and lengths of the shaft members 10 of the link haps 4 and 5 and the geometric shapes of the end link members 1a to 3a and 1c to 3c are changed on the input side and the output side. When the input and output sides of the center link members 1b to 3b are the same, the center link members 1b to 3b and the link hub are symmetric with respect to the plane of symmetry of the center link members 1b to 3b. If the angular positional relationship between the end link members 1a to 3a and lc to 3c connected to the link 4 and 5 is made the same on the input side and the output side, the link hub on the input side is obtained from geometrical symmetry. And the end link members 1a to 3a, the output side link hap 5 and the end link members 1c to 3c move in the same way, and the input side and the output side rotate at the same rotation angle at the same rotation angle. . The symmetric surface of the center link members 1b to 3b when rotating at a constant speed is called a constant speed bisecting surface.

Therefore, by arranging a plurality of link mechanisms 1 to 3 having the same geometric shape sharing the input side and output side link hubs 4 and 5 on the circumference, the plurality of link mechanisms 1 to 3 can move without contradiction. As the position, the center link members 1b to 3b are limited to movement only on the constant-velocity bisecting plane, so that the input side and the output side can rotate at a constant speed regardless of an arbitrary operating angle.

Four rotating pairs of each link mechanism 1 to 3, ie, two linking parts of end link members la to 3a and 1c to 3c and link happers 4 and 5, and end links By using two bearings, the members la to 3a and lc to 3c and the central link member 1b to 3b, as bearing structures, frictional resistance at the connecting parts is reduced and rotational resistance is reduced. It can ensure smooth power transmission and improve durability. By applying a preload to this bearing structure, the radial gap and thrust gap are eliminated, rattling at the connecting part can be suppressed, the rotational phase difference between input and output can be eliminated, and constant velocity can be maintained and vibration can be maintained. And abnormal noise can be suppressed. In particular, in the bearing structure, by setting the bearing clearance to a negative clearance, backlash generated between input and output can be reduced.

As shown in FIGS. 1 and 3, the drive mechanism of the link mechanisms 1 to 3 includes a gear section 11 formed on the inner end of the shaft member 10 attached to the link hap 4 on the input side, and a connecting gear 18. The reduction gear unit 19 is connected to the output shaft 21 via a drive motor 20 which is an actuator. The reduction gear unit 19 and the drive motor 20 are housed in an actuator case m arranged below the ring hub 4.

In this embodiment, a gear is used as the driving force transmitting means. Alternatively, a direct drive by a belt, a chain, or a cylinder may be used. In addition to the above-described motor, a direct drive actuator composed of a rack and a binion can be used as the rotary drive actuator. Further, in this embodiment, the drive control of the three link mechanisms is performed by the actuator, but the drive control of the two link mechanisms may be performed.

Claims

- The scope of the claims

1. The end link members are rotatably connected to the link haps arranged on the input and output sides, and the end link members on the input side and output side are rotatable with respect to the center link member. A link actuating device having at least three sets of link mechanisms connected to the link hub and having the input side and the output side geometrically identical with respect to the cross section at the center of each link mechanism, wherein the link hub has a bearing outer ring. A link actuating device characterized in that a bearing structure is embedded in the link hap by incorporating a bearing inner ring and an end link member.

2. The link hub has an annular shape having a center hole in the axial direction, and a shaft member is inserted via a bearing into a through hole formed in the radial direction, and an end link is provided on an outer shaft end of the shaft member. The link actuating device according to claim 1, wherein the members are combined.

3. The link according to claim 1, wherein a rotation transmitting portion is provided at an inner shaft end of the shaft member, and an actuator for controlling a rotation angle position of the end link member is coupled via the rotation transmitting portion. Actuator.

4. The link actuating device according to claim 3, wherein the actuator is configured to be detachable from a link mechanism.

5. The bearing structure according to any one of claims 1 to 4, wherein a bearing structure is embedded in the center link member by including a bearing outer ring in the center link member and connecting the bearing inner ring to an end link member. Link actuating device.

6. The link actuating device according to claim 5, wherein a shaft portion is integrally provided at one end of the end link member, and the shaft portion is inserted into a through hole formed in the central link member via a bearing.