JP2007009975A - Rotating biasing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve various problems of a conventional rotation urging device and to obtain an epoch-making device capable of three-dimensional rotation.
An inner member 2 having an inner raceway surface 21 on an outer surface, an outer member 3 having an outer raceway surface 31 on an inner surface and capable of three-dimensional relative rotation between the inner member 2 and the inner raceway. The rotation urging device 1 includes a rolling element 4 interposed between a surface 21 and an outer raceway surface 31 so as to follow the three-dimensional relative rotation so as to be able to roll. At least one of the inner raceway surface 21 and the outer raceway surface 31 rolls the rolling element 4 with the three-dimensional relative rotation of the inner member 2 and the outer member 3, and the holding interval of the rolling element 4 is gradually narrowed. And having at least a part of deformed raceway surfaces 2k and 3k for imparting a rotational biasing force between the inner and outer members in a direction to eliminate the three-dimensional relative rotation between the inner and outer members caused by the relative rotation. Yes.
[Selection] Figure 1

Description

  The present invention relates to a rotation urging device having spring elasticity in a three-dimensional rotation direction.

Conventionally, for example, coil springs are used for joint mechanisms such as industrial robots and artificial hands / legs for assisting driving and maintaining arm balance. For example, Patent Document 1 uses a torsion coil spring that applies a torque for balancing the horizontal arm to the horizontal arm drive shaft (see Patent Document 1).
JP-A-9-70789

  In a joint mechanism such as the above-described prior art, a three-dimensional operation may be required between members connected via the joint mechanism. In such a case, a method of providing a plurality of rotating shafts oriented in different directions, such as a universal joint, is used. On the other hand, when an urging force is applied to the three-dimensional operation of such a joint mechanism, it is necessary to add a rotating urging member such as a torsion coil spring as in the prior art.

  Therefore, when trying to obtain a rotation biasing device that generates a biasing force in a direction that eliminates the three-dimensional movement while allowing the three-dimensional movement, the above-described universal joint and the torsion coil spring are combined. Must be used in combination. In addition, since the torsion coil spring only applies an urging force to one rotation direction (two-dimensional rotation direction), a plurality of torsional springs are required to obtain the urging force in three dimensions. A coil spring is required. Further, in this case, a joint for joining a mechanism such as a universal joint and a torsion coil spring or the like is also required. Therefore, there is a problem that the structure of the rotation urging device becomes complicated, the number of parts and the assembling cost increase, and the reliability decreases.

Furthermore, there are various problems in the prior art using a rotating biasing member such as a torsion coil spring or an elastic material.
First, when a torsion coil spring or the like is used, there is a problem that design freedom is low. For example, in order to change the torsion spring constant, in the case of a torsion coil spring, the number of turns and the winding diameter are changed, and when an elastic member such as rubber is used, the material and thickness of the elastic member are changed. The design range of the torsion spring constant obtained by the change is limited. Therefore, the range of torsion spring constants obtained with the same size (physique) in the conventional rotation biasing member is extremely limited. Furthermore, in the case of a torsion coil spring, the relationship between the torsion angle and the torsion spring constant is linear, and the torsion spring constant can be changed freely according to the torsion angle, such as changing the torsion spring constant non-linearly with respect to the torsion angle. I couldn't.
Secondly, torsion coil springs and the like have a problem that they are liable to deteriorate due to continuous use or change with time and have a short life.
Thirdly, in the rotation urging device using a torsion coil spring or the like, the degree of design freedom is low and the structure is likely to be complicated as described above. Therefore, the size (physique) of the rotation urging device tends to be large, There was a limit to miniaturization.

  The present invention is a rotation urging device having a new structure based on a completely different technical idea from the conventional one. That is, the present invention aims to solve various problems in the case of using a conventional member such as a torsion coil spring and to obtain an innovative rotation biasing device that can obtain a three-dimensional rotation biasing force. Yes.

  The rotation urging device of the present invention includes an inner member having an inner raceway surface on an outer surface, an outer raceway surface on an inner surface, and an outer member capable of relatively rotating three-dimensionally with the inner member, A rolling element interposed between the inner raceway surface and the outer raceway surface so as to be able to roll following the three-dimensional relative rotation, and at least one of the inner raceway surface and the outer raceway surface is the inner member. The three-dimensional relative rotation between the inner and outer members caused by the relative rotation is reduced by gradually narrowing the holding interval of the rolling elements while rolling the rolling elements with the three-dimensional relative rotation of the outer member and the outer member. It is characterized in that it has at least a part of a deformed raceway surface that imparts a rotational biasing force in the direction to the inner and outer members.

According to this configuration, a three-dimensional rotation biasing function can be provided with a simple configuration that does not use a torsion coil spring or the like. In addition, the design of the deformed raceway surface can freely design a rotational urging force (hereinafter also referred to as rotational rigidity) at the time of three-dimensional relative rotation, and the design freedom is extremely high. And according to the said structure, the force which acts between inner and outer members can be supported by a rolling element, and three-dimensional relative rotation is attained. Therefore, according to the present invention, a device having both a three-dimensional rotation function and a three-dimensional rotation biasing function can be provided.
Note that three-dimensional relative rotation refers to relative rotation in which two or more relative rotation axes exist.

  In the rotation urging device, the outer member has a hollow portion therein, and the inner member is disposed in the hollow portion of the outer member and can be rotated three-dimensionally by the outer member and the rolling element. And an inner connecting portion extending from the inner member and extending through the outer member to the outside, and provided in a part of the outer member, allowing the inner connecting portion to pass through and the inner connecting portion. It is preferable to have a configuration that includes an opening that secures a movable range of the inner connecting portion accompanying relative rotation of the member and the outer member.

  If it does in this way, an inner side member and other members (peripheral member connected with a rotation energizing device of the present invention) can be easily connected via an inner side connection part. Accordingly, by connecting the inner member to the first other member and connecting the outer member to the second other member, the rotational biasing force acting between the inner member and the outer member can be taken out and used. Becomes easy. Moreover, an inner side connection part can be penetrated by an outer side member by an opening part. In addition, since the movable range of the inner connecting portion is secured by the opening, three-dimensional relative rotation between the inner member and the outer member is possible even in the presence of the inner connecting portion.

  A three-dimensional rotation urging device having a simple structure and a high degree of design freedom can be obtained by a completely different technical idea of applying a rotation urging force between the inner and outer members by a deformed raceway surface.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 3 show a rotation urging device 1 according to a first embodiment of the present invention, FIG. 1 is a perspective view thereof, FIG. 2 is a partially sectional perspective view thereof, and FIG. 3 is a sectional view thereof. It is. In FIG. 1, internal contour lines and ridge lines that are not visible from the outside are indicated by broken lines.

  The rotation urging device 1 is configured to be three-dimensionally rotatable by a substantially spherical outer member 3 having a hollow portion inside and the outer member 3 and the sphere 4 disposed in the hollow portion of the outer member 3. And a supported inner member 2. The outer surface of the inner member 2 is an inner raceway surface 21, and the inner surface of the outer member 3 is an outer raceway surface 31. A ball 4 as a rolling element is interposed between the inner raceway surface 21 and the outer raceway surface 31. A plurality of spheres 4 are provided around the inner member 2 (12 in the rotation urging device 1), and these spheres 4 are arranged at the center position of the hollow portion of the outer member 3. Is supported from the surroundings.

  An inner connecting portion 5 that extends from the inner member 2 and penetrates the outer member 3 to the outside (outside of the outer member 3) is attached to the inner member 2. The inner member 2 and the inner connecting portion 5 are integrated. On the other hand, a part of the outer member 3 is provided with an opening 6 that allows the inner connecting portion 5 to penetrate the outer member 3. The opening 6 is formed by a through hole 7 that communicates the outer surface of the outer member 3 and the hollow portion. An outer protrusion 8 is integrally attached to the outer member 3. In the outer member 3, the outer protrusion 8 is located on the substantially opposite side of the through hole 7. And the inner side connection part 5 and the outer side protrusion part 8 are extended toward the mutually opposite side substantially.

  The inner member 2 and the outer member 3 can rotate relative to each other three-dimensionally. The sphere 4 rolls following the three-dimensional relative rotation between the inner raceway surface 21 and the outer raceway surface 31. As a result, the inner connecting part 5 can be moved freely in the opening 6. Since the through-hole 7 has an inner diameter larger than the thickness of the inner connecting portion 5, a gap that is a movable range of the inner connecting portion 5 is secured around the inner connecting portion 5. In other words, the movable range of the inner connecting portion 5 is limited to the existence range of the opening 6. Increasing the range of the opening 6 increases the movable range of the inner connecting portion 5, while increasing the range of the opening 6 reduces the range of the outer raceway surface 31. Therefore, the installation range of the opening 6 is determined in consideration of the balance between the movable range of the opening 6 and the range of the outer raceway surface 31 (that is, the movable range of the rolling element), the use of the rotation urging device 1, and the like. it can. If the range of the opening 6 is too large, the inner member 2 cannot be supported from the surroundings. Therefore, the opening 6 is provided in a range in which the inner member 2 can be supported from the periphery.

  Although there are a plurality of relative rotational axes of the inner member 2 and the outer member 3, all the rotational axes pass through a single center point c. On the other hand, the outer member 3 has a generally hollow sphere as a whole, but its inner surface, that is, the outer raceway surface 31, is not a simple spherical surface (a sphere centered on the center point c). On the other hand, the outer surface of the inner member 2, that is, the inner raceway surface 21, is not a simple spherical surface (a sphere centered on the center point c).

  The outer raceway surface 31 is constituted by a continuous irregularly shaped track surface that is a surface different from the spherical surface centered on the center point c, that is, the outer deformed raceway surface 3k. Similarly, the inner raceway surface 21 is constituted by a continuous irregularly shaped raceway surface that is a surface different from the spherical surface centered on the center point c, that is, the inner variant raceway surface 2k.

  The inner deformed raceway surface 2k and the outer deformed raceway surface 3k gradually narrow the holding interval of the balls 4 while rolling the balls 4 with the three-dimensional relative rotation between the inner member 2 and the outer member 3. A rotational biasing force in a direction to eliminate the three-dimensional relative rotation between the inner and outer members 2 and 3 caused by the relative rotation is applied between the inner and outer members 2 and 3. In the state of FIGS. 1 to 3, the holding interval of the spheres 4 is the widest, and this state is hereinafter referred to as a reference state. In this reference state, no rotational biasing force is generated. However, as the inner member 2 and the outer member 3 are rotated relative to each other from the reference state, the holding interval of the balls 4 is gradually reduced. The rotational biasing force is generated in the above.

  The inner raceway surface 21 is composed of two inner deformed raceway surfaces 2k. The inner deformed raceway surface 2k is a convex curved surface. An inner central ridge line 21b that bisects the inner raceway surface 21 at the center of the inner member 2 is a circle located in a single plane. When the plane including the inner central ridge line 21b is defined as the inner equatorial plane p1 (see FIG. 3), the two inner deformed raceway surfaces 2k are symmetric with respect to the inner equatorial plane p1 (however, the inner connecting portion 5). Excluding the part.)

  When an axis that passes through the center point c1 of the inner central ridge line 21b and is perpendicular to the inner equatorial plane p1 is defined as the axis z1 (see FIG. 3), the cross-sectional shape of the inner raceway surface 21 is the same for any cross section that includes the axis z1. . That is, the cross-sectional shape of the inner raceway surface 21 is the shape shown in FIG. 3 regardless of the cross-section including the axis line z1. In this sectional view, the radius of curvature 2kr of the inner deformed raceway surface 2k is larger than the length r1 from the center point c1 to the initial contact 2m. 3, when the contact point between the sphere 4 and the outer member 3 in the reference state is the initial contact point 3m, and the contact point between the sphere 4 and the inner member 2 in the reference state is the initial contact point 2m, The center of curvature 2kc of the inner deformed raceway surface 2k that is in contact with is on the extension of the initial contact 2m, the initial contact 3m, and the straight line L1 that connects the center point c1.

  On the other hand, the outer raceway surface 31 is composed of two outer deformed raceway surfaces 3k. Each of the outer deformed raceway surfaces 3k is a concave curved surface. An outer central ridge line 31b that bisects the outer raceway surface 31 at the center of the outer raceway surface 31 is a circle located in a single plane. When the plane including the outer central ridge line 31b is defined as the outer equatorial plane p2 (see FIG. 3), the two outer deformed orbital planes 3k are symmetrical with each other with the outer equatorial plane p2 as a symmetry plane (however, due to the opening 6). Excluding missing parts.) In the reference state, the inner equator plane p1 and the outer equator plane p2 are the same plane.

  A cross-sectional shape of the outer raceway surface 31 when an axis that passes through the center point c2 of the outer center ridge line 31b (coincides with the center point c and the center point c1 described above) and is perpendicular to the outer equatorial plane p2 is the axis line z2 (see FIG. 3). Are the same for any cross section including the axis z2. That is, the cross-sectional shape of the outer raceway surface 31 is the shape shown in FIG. 3 regardless of the cross-section including the axis line z2. In this sectional view, the radius of curvature 3kr of the outer deformed raceway surface 3k is smaller than the length r2 from the center point c2 to the initial contact 3m. In the reference state, the shaft portion z2 coincides with the axis line z1 described above. 3, the center of curvature 3kc of the outer deformed raceway surface 3k with which the sphere 4 is in contact is the initial contact point 2m in contact with the sphere 4 and the straight line L2 connecting the initial contact point 3m and the center point c2 (the straight line L1 described above). And on the straight line L2 closer to the outer deformed raceway surface 3k than the center point c2.

  As described above, the cross-sectional shape of the inner deformed raceway surface 2k is axisymmetric with respect to the axis line z1 in any cross section including the axis line z1, and the cross-sectional shape of the outer deformed track surface 3k is the axis line z2 in any cross section including the axis line z2. With respect to the line symmetry. Therefore, when the inner member 2 is axially rotated around the axis line z1 or when the outer member 3 is axially rotated around the axis line z2, the balls 4 roll while maintaining a constant clamping interval. Therefore, the pinching interval of the spheres 4 does not change by these shaft rotations, and the inner member 2 and the outer member 3 can freely rotate the shaft. In other words, the shaft rotation biasing force in the direction to cancel the shaft rotation is not generated by the shaft rotation. In the rotation urging device 1, the inner connecting portion 5 and the outer protruding portion 8 are coaxial and extend in opposite directions in the reference state.

  On the other hand, when the inner member 2 and the outer member 3 are rotated relative to each other, the angle formed between the axis line z1 and the axis line z2 changes. In this case, a rotational biasing force is generated. That is, by providing the inner deformed track surface 2k and the outer deformed track surface 3k as described above, the ball 4 rolls with the relative rotation of the inner and outer members 2 and 3, and the holding interval of the balls 4 is gradually narrowed. . Therefore, the sphere 4 is elastically deformed by compression and a rotational biasing force is generated.

Next, the principle that the rotation biasing force is generated will be described.
As described above, in the reference state, the sphere 4 is disposed at a position in contact with the initial contact point 3m and the initial contact point 2m. ) Is the widest state. Therefore, in this reference state, the compressive force acting on the sphere 4 from both the raceway surfaces 2k and 3k becomes a minimum value (for example, 0). Note that the radial distance between the initial contact 2m and the initial contact 3m in the reference state is approximately equal to the diameter of the sphere 4, but a slight gap (plus gap or minus gap) may be given.

  Next, when the inner member 2 and the outer member 3 are relatively rotated three-dimensionally in an arbitrary direction from this reference state, the balls 4 roll and the holding interval of the balls 4 is gradually reduced. Therefore, with this relative rotation, the sphere 4 is compressed by the inner raceway surface 21 and the outer raceway surface 31 and elastically deformed.

  The point where the rotational biasing force is generated will be described in more detail. FIG. 4 is a cross-sectional view for explaining the rotational urging force generated by the rotational urging device 1, and only the cross-sectional lines of the inner deformed track surface 2k, the outer deformed track surface 3k, and the sphere 4 are easy to understand. Is shown. FIG. 4 shows a balanced state in which the inner member 2 is fixed and the outer member 3 is rotated counterclockwise by an angle θ. In the reference state, the initial contact 3m is located at a position 3mi on the x axis in FIG. 4, and the initial contact 2m is also on the x axis. In this reference state, the center Pr of the sphere 4 is also on the x axis. When the outer member 3 is rotated counterclockwise by the angle θ from such a reference state, the ball 4 rolls counterclockwise to the position shown in FIG. The revolution angle of the sphere 4 due to this rolling is an angle φi with respect to the center of curvature 2kc of the inner deformed raceway surface 2k. At this time, if the center of the contact position between the inner deformed raceway surface 2k and the sphere 4 is Pi and the center of the contact position between the outer deformed track surface 3k and the sphere 4 is Po, the distance between Pi and Po is the reference. It is narrower than the distance between the initial contact 2m and the initial contact 3m in the state, and is smaller than the diameter 2Rr of the sphere 4 (twice the radius Rr of the sphere 4).

  Therefore, the sphere 4 receives the vertical force Qi from the inner raceway surface 21 and also receives the vertical force Qo from the outer raceway surface 31 and undergoes compression elastic deformation. In a balanced and stationary state, almost no tangential force acts on the sphere 4, and the points Ci, Co, Pi, Pr, Po are aligned on the straight line T1, as shown in FIG. The directions of the vectors of the vertical force Qi and the vertical force Qo are also the same as the straight line T1, and the vertical force Qi ′ received by the inner member 2 from the sphere 4 and the vertical force Qo ′ received by the outer member 3 from the sphere 4 are also obtained. The direction is the same as the straight line T1. The vertical force Qo ′ received by the outer member 3 from the sphere 4 is different from the direction connecting the center Po of the contact position with the sphere 4 and the center point c (hereinafter also referred to as the center direction). It has a clockwise component together with a component in the center direction. In this way, the outer member 3 receives a clockwise moment (hereinafter also referred to as a rotation biasing moment) that generates a rotation biasing force. The magnitude of the rotation urging moment is [(size of vector Qo ′) × (distance U1 from center point c to straight line T1)]. In the balanced state of FIG. 4, the rotational biasing moment is balanced with the moment of the external force that tries to rotate the outer member 3 counterclockwise.

  As described above, the inner deformed track surface 2k is a convex curved surface, and the outer deformed track surface 3k is a concave curved surface. Moreover, each of the inner deformed track surface 2k and the outer deformed track surface 3k constitutes a smoothly continuous curved surface. The inner raceway surface 21 does not have a smoothly continuous curved surface only in the inner central ridge line 21b and the portion of the vertex t1 that is the intersection of the axis line z1 and the inner raceway surface 21. In addition, the outer raceway surface 31 does not have a smoothly continuous curved surface only in the outer central ridgeline 31b and the portion of the vertex t2 that is the intersection of the axis line z2 and the outer raceway surface 31. Therefore, as long as the contact position between the sphere 4 and the raceway surface does not reach the boundary lines 21b and 31b and the vertices t1 and t2, the raceway surface spacing at the sphere 4 contact position associated with the relative rotation between the inner member 2 and the outer member 3 is It will change gradually. In the rotation urging device 1, the entire installation area of the opening 6 is the movable range of the inner connecting portion 5, and the clamping interval of the spheres 4 gradually changes over the entire movable range. Accordingly, a rotational biasing force between the inner member 2 and the outer member 3 is generated in the entire movable range of the inner connecting portion 5.

  According to the rotation urging device 1, the rotation urging function can be provided with a simple configuration without using a torsion coil spring or the like. Therefore, it is possible to suppress deterioration due to continuous use or change with time as compared with the conventional rotation urging member, and it is possible to extend the life. Conventionally, when an urging force is obtained with respect to a three-dimensional relative rotation, for example, two or more shafts oriented in different directions, and two or more torsion members that urge the respective shafts to rotate. A coil spring was required. However, the rotation urging device 1 has a simple structure, but is a very epoch-making device having both a rotation function in a three-dimensional direction and a rotation urging function in a three-dimensional direction. . There are an infinite number of relative rotation axes, and a very high degree of freedom of rotation can be obtained. Further, unlike the conventional rotation urging member, peripheral members such as an outer member and an inner member that rotate relative to each other and a joint portion that joins the rotation urging member can be omitted. Therefore, the peripheral structure can be simplified, the number of parts and the assembly cost can be suppressed, the reliability can be improved, and the member can be easily downsized.

  Furthermore, in the rotation urging device 1, the degree of freedom in design such as rotation rigidity is extremely high as compared with the conventional rotation urging member. That is, the rotational rigidity can be freely designed by designing the irregular raceway surface (curvature, position of the center of curvature, etc.), the diameter of the sphere 4, and the rigidity of the sphere 4 and the inner and outer members 2 and 3, etc. The characteristics such as rotational rigidity can be set over a wide range without particularly changing the size (physique) of the member. In the conventional torsion coil spring, the relationship between the phase difference (twist angle) and the spring constant is linear (constant). However, in the rotation urging device 1, the rotation bias device 1 rotates with respect to the angle formed by the axis z1 and the axis z2. The dynamic rigidity can be changed nonlinearly, and the degree of freedom in design is extremely high.

  In addition, each of the irregularly shaped raceways 2k and 3k has a shape that is an axis target in an arbitrary cross section including the axes z1 and z2, and therefore can be easily manufactured by, for example, rotating a ball end mill. Further, as described above, the rotation urging device 1 is free (free) with respect to the rotation around the axis line z1 and the axis line z2, and thus can be suitably used in applications requiring such a function.

  In the rotation urging device 1, a three-dimensional rotation and a three-dimensional rotation urging force can be obtained while supporting the forces acting between the inner member 2 and the outer member 3 with each other. It can be used for joint members such as robots, artificial hands and artificial legs. Further, in the rotation urging device 1, the first external member is connected to the inner connecting portion 5, and the second external member is connected to the outer protruding portion 8, thereby making it easy to attach to the external member. .

  5 to 9 are views of a rotation urging device 50 according to a second embodiment of the present invention, FIG. 5 is a perspective view thereof, FIG. 6 is a partially sectional perspective view, and FIG. 7 is a sectional view. . FIG. 8 is a perspective view in which the inner member 2 (and the inner connecting portion 5 integrally attached to the inner member 2) is extracted from the perspective view of FIG. Further, FIG. 9 is a perspective view in which a line indicating the outer raceway surface 31 of the outer member 3 is extracted from the perspective view of FIG. 1 to 3 are also diagrams in the reference state.

The configuration of the rotation urging device 50 is the same as that of the rotation urging device 1 of the first embodiment described above except for the shapes of the outer raceway surface 31 and the inner raceway surface 21. Therefore, below, description is abbreviate | omitted about the part similar to the rotation urging | biasing apparatus 1. FIG.
Further, the outer raceway surface 31 and the inner raceway surface 21 are symmetrical with respect to the inner equatorial plane p1 and the outer equatorial plane p2 except for the portion where the inner connecting portion 5 and the through hole 7 are present. Therefore, in the following description of the inner raceway surface 21 and the outer raceway surface 31, in order to simplify the explanation, the presence of the inner coupling portion 5 and the through hole 7 is appropriately ignored, and the inner equator plane p1 and the outer equator plane p2 are symmetric. It will be described as having a simple shape.

  As shown in FIG. 8 and the like, the inner raceway surface 21 is composed of eight inner deformed raceway surfaces 2k. All of these eight inner deformed raceway surfaces 2k have the same shape (except for the portion provided with the inner connecting portion 5). Each inner deformed raceway surface 2k is a convex curved surface forming a part of a spherical surface. Eight inner deformed raceway surfaces 2k made of a part of a spherical surface are arranged in the same manner as the eight planes constituting the regular octahedron. In other words, the inner raceway surface 21 is formed by replacing each of the eight planes constituting the regular octahedron with a part of a spherical surface (that is, the inner deformed raceway surface 2k). When the center point of the inscribed sphere inscribed in the inner raceway surface 21 is cn, the radius of curvature (not shown) of the spherical surface constituting each inner deformed raceway surface 2k is from the distance r3 from the center point cn to the initial contact 2m. Is also big. The center of curvature (not shown) of each inner deformed raceway surface 2k is located on a straight line L3 connecting the initial contact 3m, the initial contact 2m, and the center point cn. Further, the center of curvature of each inner deformed raceway surface 2k is farther from the inner deformed track surface 2k than the center point cn.

  On the other hand, as shown in FIG. 9 and the like, the outer raceway surface 31 is also composed of eight outer deformed raceway surfaces 3k. All of these eight outer deformed raceway surfaces 3k have the same shape (excluding the portion where the through hole 7 is provided). Each outer deformed raceway surface 3k is a concave curved surface forming a part of a spherical surface. Eight outer deformed raceway surfaces 3k made of a part of a spherical surface are arranged in the same manner as the eight planes constituting the regular octahedron. In other words, the outer raceway surface 31 is formed by replacing each of the eight planes constituting the regular octahedron with a part of a spherical surface (that is, the outer deformed raceway surface 3k). When the center point of the circumscribed sphere circumscribing the outer raceway surface 31 is defined as cg, the radius of curvature (not shown) of each outer deformed raceway surface 3k is smaller than the distance r4 between the center point cg and the initial contact 3m. The center of curvature (not shown) of each outer deformed raceway surface 3k is located on a straight line L4 connecting the initial contact 3m, the initial contact 2m, and the center point cb. The center of curvature of each outer deformed raceway surface 3k is located on the inner deformed track surface 2k side with respect to the center point cn.

  The rotation urging device 50 has a total of eight spheres 4 arranged one by one for each of the eight sets of deformed raceway surfaces 2k and 3k arranged in a regular octahedron shape. By making the rolling element into a sphere 4, it is possible to provide a rolling element that can follow the three-dimensional relative rotation between the inner member 2 and the outer member 3.

  Each of the inner deformed track surface 2k and the outer deformed track surface 3k is a spherical surface and has a maximum diameter at the initial contacts 3m and 2m. Therefore, in the rotation urging device 50, the urging force is applied while the holding interval of the sphere 4 is gradually narrowed regardless of the direction in which the sphere 4 moves from the position of the reference state. Therefore, in the rotation urging device 50, even when the inner member 2 or the outer member 3 is axially rotated, the rotation urging force (axial rotation) in a direction to cancel the relative rotation between the inner member 2 and the outer member 3 due to the axial rotation. Urging force) occurs. The axial rotation of the inner member 2 means rotation of the inner member 2 around the axis z3 that passes through the center point cn and is perpendicular to the inner equatorial plane p1. The axial rotation of the outer member 3 means the rotation of the outer member 3 about the axis z4 that passes through the center point cg and is perpendicular to the outer equatorial plane p2. In the reference state shown in FIG. 7, the axis z3 and the axis z4 are coaxial.

  In the rotation urging device 1, the inner member 2 and the outer member 3 can freely rotate about the axis, but in the rotation urging device 50 of the second embodiment, the shaft rotation of the inner member 2 and the outer member 3. Also, a rotation biasing force (shaft rotation biasing force) is applied. The reason why this axial rotation biasing force is generated is the same as the reason for the generation of the rotation biasing force in the rotation biasing device 1, and is as described with reference to FIG. That is, in the rotation urging device 50, unlike the rotation urging device 1, each of the deformed raceway surfaces 2 k and 3 k is a spherical surface (a part of the spherical surface). Thus, the shaft rotation urging force is generated. In the rotation urging device 50, similarly to the rotation urging device 1, a rotation urging force in a direction to cancel the three-dimensional relative rotation between the inner member 2 and the outer member 3 is also generated. The reason for this is also as described above with reference to FIG.

  Unlike the conventional torsion coil spring and the like, the rotation urging device of the present invention also has a support function for supporting the force acting between the inner and outer members 2 and 3. The function capable of supporting the load between the inner and outer members in this way is an effect that cannot be obtained at all by conventional torsion coil springs or rubber. Therefore, if the rotation urging device of the present invention is used for an application (for example, a joint member) that has been used in combination with a conventional rotation urging member and a rotation axis, the burden on the rotation axis can be reduced or the rotation can be reduced. The advantage that an axis is unnecessary can be obtained.

  In the present invention, the shape or the like of the rolling element is not limited. However, the rolling element needs to be able to roll following the three-dimensional relative rotation of the inner member 2 and the outer member 3, and a sphere is preferable from this viewpoint. . Further, in order to increase the degree of freedom in setting the rotational rigidity, a hollow rolling element (for example, a hollow sphere) that is easily elastically compressed and deformed can be used. Further, the material of the rolling element is appropriately selected according to the performance required for the rotation urging device.

In each of the above embodiments, local elastic deformation in the contact region between the inner member 2 and the outer member 3 and the rolling element during relative rotation is mainly considered. However, the macroscopic elastic deformation of the inner member 2 and / or the outer member 3 may be increased by reducing the thickness of the inner member 2 or the outer member 3. Furthermore, it is good also as a structure which obtains a rotation urging | biasing force mainly by elastically deforming the inner member 2 or the outer member 3 without substantially rolling elastically. By adding the rigidity of the inner member and the outer member as design elements, the degree of design freedom of the present invention is further improved.
For example, by changing the thickness (average thickness), thickness distribution, or material of the inner member 2 and the outer member 3, the rigidity of the inner and outer members (the rigidity against the pressing force by the rolling elements) can be changed. As a mode of changing the wall thickness distribution, the wall thickness of the inner member and the outer member can be changed uniformly in the circumferential direction. Further, the inner member 2 may be a hollow member, or a slit or the like may be provided in the inner member 2 or the outer member 3 to increase the elastic deformation of the inner member 2 or the outer member 3.

It is a perspective view of the rotation urging device which is the first embodiment of the present invention. It is a partial cross section perspective view of the rotation urging device of FIG. It is sectional drawing of the rotation urging | biasing apparatus of FIG. It is a figure for demonstrating the principle which rotation energizing force generate | occur | produces. It is a perspective view of the rotation urging device which is a second embodiment of the present invention. It is a partial cross section perspective view of the rotation urging device of FIG. It is sectional drawing of the rotation urging | biasing apparatus of FIG. FIG. 6 is a perspective view of an inner member (and an inner connecting portion) of the rotation urging device in FIG. 5. It is a perspective view which shows the line | wire which comprises the outer track surface of an outer member among the rotation urging | biasing apparatuses of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating biasing device 2 Inner member 2k Inner deformed track surface 21 Inner track surface 3 Outer member 3k Outer deformed track surface 31 Outer track surface 4 Ball (rolling element)
5 Inner connecting part 6 Opening part 50 Rotating biasing device

Claims (2)

An inner member having an inner raceway surface on the outer surface;
An outer member having an outer raceway surface on the inner surface, and three-dimensional relative rotation with the inner member;
A rolling element interposed between the inner raceway surface and the outer raceway surface so as to be able to roll following the three-dimensional relative rotation;
At least one of the inner raceway surface and the outer raceway surface rolls the rolling element with the three-dimensional relative rotation of the inner member and the outer member, gradually reducing the holding interval of the rolling element, and Rotation characterized by having at least part of a deformed raceway surface that imparts a urging biasing force between the inner and outer members in a direction to eliminate the three-dimensional relative rotation between the inner and outer members caused by the rotation. Energizing device. The outer member has a hollow portion therein,
The inner member is disposed in the hollow portion of the outer member and is supported by the outer member and the rolling element so as to be three-dimensionally rotatable,
An inner connecting portion extending from the inner member and penetrating the outer member to reach the outside;
An opening provided in a part of the outer member, allowing the penetration of the inner connecting portion and securing a movable range of the inner connecting portion in association with relative rotation between the inner member and the outer member;
The rotation urging device according to claim 1, further comprising:

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