JP4942705B2 - Bending gear system - Google Patents

Description

  The present invention relates to a flexure meshing gear device.

  The flexure meshing gear device includes an internal gear having rigidity, an external gear having flexibility that can be internally meshed with the internal gear, and the internal gear by bending and deforming the external gear. And a vibration generator that realizes internal meshing between the tooth gear and the external gear.

  Here, Patent Document 1 proposes that a trochoidal tooth profile is used for the external gear of the flexure meshing gear device, and an arc tooth profile is used for the internal gear. In order to achieve perfect theoretical meshing, it is described that the external gear bent and deformed by the vibration generator is a circular arc (a part of a perfect circle) at the portion meshed with the internal gear. ing. Further, the radius of curvature of the arc of the external gear is determined with respect to the portion that meshes with the internal gear so that a large bending stress is not generated in the external gear that is bent and deformed by the vibrator.

JP-A-6-213287

  However, Patent Document 1 does not particularly suggest the curvature radius of the arc of the external gear in a portion that does not mesh with the internal gear. For this reason, depending on the shape of the portion that does not mesh with the internal gear, a large bending stress may be generated on the entire external gear, or a large resistance may be given to the operation of the bearing provided on the outer periphery of the vibrator. There is a risk.

  Therefore, the present invention was made to solve the above-mentioned conventional problems, and in a flexure meshing gear device that requires deformation of the external gear, the bending stress due to deformation of the external gear is suppressed as much as possible. It is an object of the present invention to provide a flexure meshing gear device capable of improving the transmission torque and enabling a more efficient flexure meshing gear device to be designed.

The present invention relates to a rigid internal gear (deceleration internal gear), a flexible external gear that can be internally meshed with the internal gear, and the external gear on its outer periphery. A flexure meshing system comprising: a vibration generator that realizes internal meshing between the internal gear and the external gear by bending deformation; and a bearing disposed between the vibration coil and the external gear. In the gear type gear device, the shape of the outer periphery of the vibration exciter is a shape obtained by connecting arcs having two different radii of curvature, and the tangent line at the connecting portion of the arcs is common. It has been solved.

  In the present invention, since the shape of the outer periphery of the vibrator is a shape obtained by connecting two arcs of different radii of curvature, the flexural stress of the external gear at each arc portion is constant. And since the tangent is common in the connection part of the said two circular arcs, the rapid bending deformation in the connection part is prevented. That is, since the change in the radius of curvature of the external gear is minimized, the change in the flexural stress of the external gear is minimized, and an increase in the flexural stress is prevented. For this reason, since the loss of the transmission torque by bending stress can be reduced, the improvement of a transmission torque can be aimed at.

  In addition, since the vibrator has a shape in which two arcs are connected and the tangent line is common, parameters for designing the shape of the vibrator can be simplified. For this reason, the efficient design of the flexure meshing gear device is enabled.

  ADVANTAGE OF THE INVENTION According to this invention, the bending stress by a deformation | transformation of an external gear can be suppressed as much as possible, and while improving a transmission torque, the design of a bending mesh type gear apparatus with higher efficiency is possible.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  1 is a cross-sectional view showing an overall configuration of an example of a flexure meshing gear device according to this embodiment of the present invention, FIG. 2 is a side view of FIG. 1, FIG. 3 is a diagram showing a vibration generator, and FIG. 5 is an enlarged view for explaining the shape of the vibrator, FIG. 5 is a schematic view of a combination of a vibrator and a vibrator bearing, FIG. 6 is a conceptual diagram of meshing between a virtual external gear and an internal gear, and FIG. It is a meshing figure of an external gear and an internal gear.

  First, the overall configuration of the present embodiment will be schematically described mainly with reference to FIGS. 1 and 2.

  The flexure meshing gear device 100 includes a rigid reduction gear (internal gear) 130A having rigidity and a flexible outer gear that can be meshed with the reduction gear (internal gear) 130A. A toothed gear 120A, and a vibration generator 104 that realizes the internal meshing of the internal gear 120A for speed reduction and the external gear 120A by bending and deforming the external gear 120A on its outer periphery. I have. Here, the shape of the outer periphery of the vibrating body 104 (the shape of the outer periphery in a cross section perpendicular to the axial direction O) is an arc having two different radii of curvature R1, R2 (first arc portion FA, second arc portion SA). And the tangent line T at the connecting portion A of the arcs (first arc part FA, second arc part SA) is common.

  Hereinafter, each component will be described in detail.

  As shown in FIGS. 3 (A) and 3 (B), the vibrator 104 has a column shape, and an input shaft hole 106 into which an input shaft (not shown) is inserted is formed at the center. A keyway 108 is provided in the input shaft hole 106 so that the vibrator 104 rotates integrally with the input shaft when the input shaft is inserted and rotated.

  Here, as shown in FIG. 3A, when the vibrating body 104 is positioned at the center of the XY coordinates, the outer shape of the vibrating body 104 becomes an axisymmetric shape in both the X axis and the Y axis. Therefore, only the shape of the first quadrant of the vibrator 104 shown in FIG. 4 will be described below.

  As described above, the vibrator 104 has a shape in which two arcs are connected. Here, an arc portion of the vibrating body 104 for meshing the external gear 120A and the reduction internal gear 130A is defined as a first arc portion FA, and the radius of curvature is R1. A portion of the arc connecting the two first arc portions FA is defined as a second arc portion SA, and the radius of curvature is R2. An angle that determines the length of the first arc portion FA is defined as θ.

  At this time, as shown in FIG. 4, if the radius of the long axis direction X of the vibrating body 104 is R, the amount of eccentricity is L, and the radius of curvature R1 of the first arc portion FA is expressed by equation (1). Can do.

    R1 = RL (1)

  Also, as shown in FIG. 4, the tangent line T is common at the connecting portion A between the first arc portion FA and the second arc portion SA. As described above, the outer shape of the vibrator 104 is axisymmetric. For this reason, the curvature radius R2 of the vibrator 104 has a point B in common with the curvature radius R1 from the connecting portion A between the first arc portion FA and the second arc portion SA at the angle θ and further extends from the point B. It is the length to the intersection C with the Y axis (short axis direction of the vibrator 104). That is, the radius of curvature R2 of the second arc portion SA can be expressed by Expression (2).

    R2 = R−L + L / cos θ (2)

  As is clear from the equations (1) and (2), the radius of curvature R1 of the first arc portion FA is smaller than the radius of curvature R2 of the second arc portion SA. Here, the outer part that is bent and deformed by an arc (first arc part FA) having a small radius of curvature R1 out of two arcs (first arc part FA, second arc part SA) forming the shape of the vibrating body 104. The curvature radius of the tooth gear 120A is set equal to the curvature radius of the virtual external gear 120C. As shown in FIG. 6, the virtual external gear 120C has a perfect circle and rigidity, as shown in FIG. 6, in order to ideally mesh the external gear 120A and the reduction internal gear 130A.

  As described above, assuming the virtual external gear 120C, if the angle θ and the amount of eccentricity L are determined, the radius of curvature of the virtual external gear 120C can be obtained. And the curvature radius R1 and the curvature radius R2 which define the external shape of the vibration body 104 can be uniquely determined in consideration of the radial thickness of the vibration body bearing 110A described later. For this reason, the vibratory body 104 can be designed quickly and efficiently.

  The vibration body bearing 110A is a bearing disposed between the vibration body 104 and the external gear 120A. As shown in FIG. 1, the vibration body bearing 110A includes an inner ring 112, a cage 114A, a rolling element 116A, and an outer ring 118A. Composed. The vibration body bearing 110 </ b> A is disposed inside the external gear 120 </ b> A and on the outer periphery of the vibration body 104. Therefore, as shown in FIG. 5, the inner ring 112 contacts the vibration generator 104 inside the inner ring 112, and the inner ring 112 rotates integrally with the vibration generator 104.

  As shown in FIG. 1, the retainer 114 </ b> A holds the rolling element 116 </ b> A so as to be rotatable along the outer periphery of the inner ring 112. The rolling element 116A has a cylindrical shape. For this reason, compared with the case where rolling element 116A is a sphere, the area where rolling element 116A contacts inner ring 112 and outer ring 118A increases. That is, the load resistance of the vibration body bearing 110A can be increased. The outer ring 118A is disposed outside the rolling element 116A. The outer ring 118 </ b> A is bent and deformed by the rotation of the vibration generator 104 together with the external gear 120 </ b> A arranged on the outer side thereof.

  As shown in FIG. 1, the vibration body bearing 110B includes an inner ring 112, a cage 114B, a rolling element 116B, and an outer ring 118B, like the vibration body bearing 110A. The vibration body 104 and the inner ring 112 are common to the vibration body bearings 110A and 110B. For this reason, the vibration body bearings 110A and 110B transmit the eccentric amount L of the vibration body 104 to the external gears 120A and 120B in the same phase to bend and deform. The rolling element 116B has the same cylindrical shape as the rolling element 116A.

  As shown in FIG. 1, the external gear 120 </ b> A meshes internally with the reduction internal gear 130 </ b> A. The external gear 120A includes a base member 122 and external teeth 124A. The base member 122 is a cylindrical member that is disposed outside the vibration body bearing 110A and has flexibility to support the external teeth 124A. The external teeth 124A are constituted by cylindrical pins. The outer teeth 124 </ b> A are rotatably supported by the holding ring 126 </ b> A on the outer side so as not to fall off the base member 122 when rotated. The holding ring 126A is an annular elastic ring. In the present embodiment, two holding rings are used to hold the external teeth 124A at both ends. Note that the load applied to the outer teeth 124A when meshing with the inner teeth 128A is basically received by the base member 122 (for example, a semicircular groove structure for supporting the cylindrical shape of the outer teeth 124A). ing.

  The external gear 120B meshes internally with the output internal gear 130A as shown in FIG. Similarly to the external gear 120A, the external gear 120B includes a base member 122 and external teeth 124B, and the external teeth 124B are held on the base member 122 by a holding ring 126B. Here, the base member 122 supports the external teeth 124B together with the external teeth 124A. For this reason, the eccentric amount L of the vibrator 104 is transmitted to the external teeth 124A and the external teeth 124B in the same phase. The external teeth 124B are configured by the same number of external teeth 124A and the same cylindrical pins.

  As shown in FIG. 1, the internal gear 130A for deceleration is formed of a rigid member. The reduction internal gear 130A has a number of teeth i (i is 2 or more) larger than the number of teeth of the external teeth 124A of the external gear 120A. A casing (not shown) is fixed to the reduction internal gear 130A via a bolt hole 132A. And the internal gear 130A for deceleration reduces the rotation of the vibration body 104 by meshing with the external gear 120A.

  On the other hand, the output internal gear 130B is also formed of a rigid member, like the reduction internal gear 130A. The output internal gear 130B has the same number of teeth of the internal teeth 128B as the number of teeth of the external teeth 124B of the external gear 120B. Since the number of teeth of the external teeth 124A of the external gear 120A and the number of teeth of the external teeth 124B of the external gear 120B are the same, the number of teeth of the internal teeth 128A of the internal gear 130A for reduction is ultimately the output internal gear. It is i more than the number of teeth of the internal teeth 128B of the tooth gear 130B. Note that an output shaft (not shown) is attached to the output internal gear 130B via a bolt hole 132B, and the same rotation as the rotation of the external gear 120B is output to the outside.

  Here, as shown in FIG. 1, the retainers 114A and 114B, the rolling elements 116A and 116B, and the outer rings 118A and 118B correspond to the external teeth 124A that mesh with the reduction gear 130A in the axial direction O. The portion is divided into portions corresponding to the external teeth 124B meshing with the output internal gear 130B. For this reason, the vibration body bearing 110A can prevent the vibration body bearing 110B from being affected by the load caused by the engagement between the external gear 120A and the reduction internal gear 130A. At the same time, the vibration body bearing 110B can prevent the vibration body bearing 110A from being affected by the load caused by the engagement between the external gear 120B and the output internal gear 130B. Further, since the rolling element 116A has a cylindrical shape, the load resistance is large, and the vibration generator bearing 110A can have a long life. At the same time, the cylindrical rolling element 116A bends and deforms the base member 122, which is a cylindrical member of the external gear 120A, in parallel with the axial direction O. For this reason, the external teeth 124A of the external gear 120A that has been bent and deformed uniformly mesh with the internal teeth 128A in the axial direction O, thereby extending the life of the external teeth 124A and the internal teeth 128A and maintaining high torque transmission. . Since the rolling element 116B has the same shape as the rolling element 116A, the above-described effects are similarly exerted on the outer teeth 124B and the inner teeth 128B.

  Further, as shown in FIG. 1, the external teeth 124A and 124B are divided in the axial direction O into a portion where the reduction internal gear 130A meshes and a portion where the output internal gear 130B meshes. For this reason, the influence of meshing between the external teeth 124A and the internal teeth 128A is not given to the external teeth 124B adjacent in the axial direction O. That is, when the external gear 120A and the reduction internal gear 130A mesh with each other, the meshing area (with which the external teeth 124A and the internal teeth 128A should mesh with each other in the axial direction O is not affected by the external teeth 124B. For example, when the outer teeth 124A are not tilted, bent, or worn, the outer teeth 124A mesh with the inner teeth 128A. Similarly, the influence of meshing between the external teeth 124B and the internal teeth 128B is not given to the external teeth 124A adjacent in the axial direction O. That is, when the external gear 120B meshes with the output internal gear 130B, the meshing area that the external teeth 124B and the internal teeth 128B should mesh with each other in the axial direction O is not affected by the external teeth 124A. Mesh. That is, by dividing the external teeth 124A and 124B, it is possible to maintain rotational accuracy and prevent a reduction in transmission torque.

  Here, the virtual external gear 120C is determined in order to determine the tooth profile to be engaged. The number of teeth (102) of the internal teeth 128A of the internal gear for reduction 130A is two more than the number of teeth (100) of the external teeth 124A of the external gear 120A. That is, the tooth number difference i = 2. Accordingly, assume that the virtual external gear 120C is, for example, four teeth fewer (j = 4, j> i) than the number of teeth (102) of the reduction internal gear 130A.

  Therefore, a virtual external gear 120C having a number of teeth (98) that is four teeth less than the number of teeth (102) of the internal teeth 128A of the reduction internal gear 130A is determined, and the tooth profile is used as a reference. In this embodiment, since the external gear 120A uses a cylindrical pin as the external tooth 124A, the tooth profile is an arc tooth profile. That is, the reference tooth profile of the virtual external gear 120C is an arc tooth profile formed by the external teeth 124A. And in order to implement | achieve perfect theoretical meshing with the external tooth 124A and the internal tooth 128A, the internal tooth 128A of the trochoidal tooth profile is determined using the technical idea shown in Patent Document 1. In this way, by forming the trochoidal tooth profile on the inner tooth 128A, it is possible to realize complete theoretical meshing. In addition, the shape of the outer periphery of the vibration body 104 is determined at the stage where the virtual external gear 120C is determined. For this reason, the external gears 120 </ b> A and 120 </ b> B are bent and deformed according to the shape of the outer periphery of the vibrating body 104. In addition, you may apply another tooth profile to the tooth profile of the internal tooth 128B which meshes with the external tooth 124B.

  Next, the operation of the flexure meshing gear device 100 will be described mainly with reference to FIG.

  When the vibrator 104 is rotated by the rotation of the input shaft (not shown), the external gear 120A is bent and deformed via the vibrator bearing 110A according to the position by the rotation. At this time, the external gear 120B is also bent and deformed in the same phase as the external gear 120A via the vibration body bearing 110B.

  Here, the bending deformation of the external gear 120 </ b> A is performed according to the shape of the vibrating body 104. That is, since the curvature is constant at each position of the first arc part FA having the curvature radius R1 and the second arc part SA having the curvature radius R2 on the outer periphery of the vibration body 104 shown in FIG. It becomes constant. Since the tangent line T is the same at the position of the first arc part FA and the second arc part SA in the connecting part A, a sudden bending deformation of the bending stress at the connecting part is prevented. At the same time, since there is no abrupt position change of the rolling elements 116A and 116B in the connecting portion A, the rolling elements 116A and 116B are less slipped and torque transmission loss is small.

  When the external gear 120A is bent and deformed in the major axis direction X (FIG. 3) of the vibrator 104, the external teeth 124A mesh with the internal teeth 128A of the reduction internal gear 130A. At the same time, the external teeth 124B mesh with the internal teeth 128B of the output internal gear 130B. Here, FIG. 7A shows a state where the reduction internal gear 130A and the external gear 120A mesh, and FIG. 7B shows a state where the output internal gear 130B and the external gear 120B mesh. Each is shown. When meshing, the external teeth 124A and 124B are rotatable pins, so that loss of transmission torque due to meshing is reduced. Further, the tooth profile of the inner teeth 128A is formed so as to be theoretically meshed with the outer teeth 124A, and therefore meshes with each other with a plurality of teeth. For this reason, the surface pressure concerning a tooth surface can be reduced and a big torque can be transmitted. The external teeth 124A and 124B are held on the base member 122 by the holding rings 126A and 126B. Therefore, the external teeth 124A and 124B do not fall off due to the rotation even in a portion where the external gear 120A and the reduction internal gear 130A and the external gear 120B and the output internal gear 130B do not mesh.

  Further, when meshing, a force (direction and size) different from that of the external teeth 124B is applied to the external teeth 124A. However, the external teeth 124A and 124B are separated in the axial direction O into a portion that meshes with the reduction internal gear 130A and a portion that meshes with the output internal gear 130B. For this reason, the influence of the force applied to each external tooth 124A, 124B is mutually excluded. Furthermore, the vibration body bearings 110A and 110B arranged inside the external teeth 124A and 124B also have portions corresponding to the external teeth 124A meshing with the internal gear 130A for reduction in the axial direction O except for the inner ring 112. It is separated into portions corresponding to the external teeth 124B meshing with the output internal gear 130B. For this reason, the load caused by the reduction internal gear 130A and the output internal gear 130B does not affect the two vibration body bearings 110A and 110B having different positions in the axial direction O. At this time, since the rolling elements 116A and 116B have a cylindrical shape, the load resistance is large and a large torque can be transmitted.

  The meshing position of the external gear 120 </ b> A and the reduction internal gear 130 </ b> A rotates as the vibration body 104 moves in the long axis direction X. Here, when the vibrating body 104 rotates once, the rotation phase of the external gear 120A is delayed by a difference in the number of teeth from the internal gear 130A for deceleration. In other words, the reduction ratio of the reduction internal gear 130A can be obtained by ((the number of teeth of the external gear 120A−the number of teeth of the reduction internal gear 130A) / the number of teeth of the external gear 120A). The specific reduction ratio is ((100−102) / 100 = −1 / 50). Here, “−” indicates that the input / output is in a reverse rotation relationship.

  Since both the external gear 120B and the output internal gear 130B have the same number of teeth, the external gear 120B and the output internal gear 130B do not move with each other, and the same teeth can move. Will mesh. For this reason, the same rotation as the rotation of the external gear 120B is output from the output internal gear 130B. As a result, an output obtained by reducing the rotation of the vibrating body 104 to (−1/50) can be extracted from the output internal gear 130B.

  In this way, since the shape of the outer periphery of the vibrating body 104 is a shape in which the arcs of two different radii of curvature R1 and R2 are connected, each arc portion (the first arc portion FA and the second arc portion SA). The bending stresses of the external gears 120A and 120B in FIG. And since the tangent line T is common in the connection part A of the two arcs (the first arc part FA and the second arc part SA), rapid bending deformation at the connection part is prevented. That is, the change in the radius of curvature of the external gears 120A and 120B is minimized. For this reason, the change of the bending stress of external gear 120A, 120B becomes the minimum, and the increase in bending stress is prevented. That is, loss of transmission torque due to bending stress can be reduced, so that transmission torque can be improved.

  In addition, the vibrator 104 adopts an arc shape (second arc portion SA having a curvature radius R2) even at a portion connecting the two first arc portions FA. For example, as shown in FIG. 4, even if the length (angle θ) of the first arc portion is increased, the length of the diameter (short axis) in the Y-axis direction can be shortened by increasing the eccentricity L. For this reason, it is possible to sufficiently secure a gap generated in the minor axis direction Y that does not mesh with the external gear 120A and the reduction internal gear 130A. That is, it is easy to design to avoid interference between the external gear 120A and the reduction internal gear 130A.

  Further, since the vibrator 104 has a shape in which two arcs (first arc part FA and second arc part SA) are connected and the tangent line T is common, parameters for designing the shape of the vibrator 104 are set. Can be simplified. For this reason, the efficient design of the flexure meshing gear device 100 is enabled.

  That is, according to the present invention, the bending stress due to the deformation of the external gear 120A can be suppressed as much as possible, the transmission torque can be improved, and the flexure meshing gear device 100 can be designed more efficiently.

  Although the present invention has been described with reference to the present embodiment, the present invention is not limited to the present embodiment. That is, it goes without saying that improvements and design changes can be made without departing from the scope of the present invention.

  For example, in the present embodiment, the external teeth 124A and 124B are configured by cylindrical pins, but the present invention is not limited to this. For example, the external teeth 124A and 124B may be formed directly on the base member 122. That is, the external teeth do not have to be arc teeth, and trochoidal teeth may be used, or other teeth may be used. For the internal teeth, a tooth profile corresponding to the external teeth can be used.

  In this embodiment, the output decelerated from the output internal gear 130B is taken out, but the present invention is not limited to this. For example, instead of using the output internal gear, a so-called cup-type external gear that bends and deforms may be used, and a flexure meshing gear device that extracts only the rotation component from the external gear may be used.

  In this embodiment, the difference i between the number of teeth of the internal teeth 128A of the internal gear 130A for reduction and the number of teeth of the external teeth 124A of the external gear 120A is set to 2, but in the present invention this number of teeth is set. The difference i is not limited to 2. For example, an appropriate number may be used as long as it is an even number 2i of 2 or more. Further, the number of teeth of the virtual external gear 120C may be an appropriate number as long as it is smaller than the actual number of teeth of the external teeth 124A of the external gear 120A, and the virtual external gear 120C is not necessarily assumed.

Sectional drawing which shows the whole structure of an example of the bending meshing type gear apparatus which concerns on this embodiment of this invention. Similarly side view of FIG. The figure which also shows a vibration body Similarly, an enlarged view for explaining the shape of the vibrator Schematic diagram of a combination of a vibrator and a vibrator bearing Similarly, a conceptual diagram of meshing between a virtual external gear and an internal gear Similarly, meshing diagram of external gear and internal gear

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Flexure meshing type gear apparatus 104 ... Excitation body 110A, 110B ... Excitation body bearing 112 ... Inner ring 114A, 114B ... Cage 116A, 116B ... Rolling body 118A, 118B ... Outer ring 120A, 120B ... External gear 120C ... Virtual external gear 122 ... Base members 124A and 124B ... External teeth 126A and 126B ... Holding rings 128A and 128B ... Internal teeth 130A ... Internal gears for reduction (internal gears)
130B ... Internal gears for output 132A, 132B ... Bolt hole O ... Rotating shaft X ... Long axis direction of the exciter Y ... Short axis direction of the exciter FA ... First arc part SA ... Second arc part R ... Origin Long axis radius of the vibrator R1 ... radius of curvature of the first arc part of the vibrator R2 ... radius of curvature of the second arc part of the vibrator

Claims (2)

A rigid internal gear, a flexible external gear capable of being internally meshed with the internal gear, and bending and deforming the external gear on the outer periphery of the internal gear and the external gear. In a flexure meshing gear device comprising a vibration generating body that realizes internal meshing with a toothed gear, and a bearing disposed between the vibration generating body and the external gear ,
The flexure-gear type gear device, wherein the shape of the outer periphery of the vibration generating body is a shape obtained by connecting arcs having two different radii of curvature, and tangents at the connecting portion of the arcs are common. In claim 1,
When the difference in the number of teeth between the internal gear and the external gear is i, the difference in the number of teeth from the internal gear is j larger than i, and the internal gear has rigidity to be in mesh with the internal gear. Assuming a virtual external gear,
The tooth profile of the external gear flexibly deformed by an arc having a small radius of curvature among the two arcs forming the outer peripheral shape of the oscillator is set to be equal to the tooth profile of the virtual external gear. A flexure meshing gear device characterized by the above.

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