Patent Description:
In a gear device such as a bending meshing type gear device including an external gear which is flexibly deformed, a distortion gauge is attached to an outer periphery of a fixing frame of an internal gear, and a torque is detected from a detected distortion (for example, refer to PTL <NUM> and PTL <NUM>).

However, in the above-described gear device in the related art, since the distortion gauge is attached to the outer periphery of the fixing frame of the internal gear, the distortion gauge is located at a position where the distortion caused by the torque from the internal gear is unlikely to occur. Consequently, there is a possibility that sufficient detection accuracy may not be obtained.

An object of the present invention is to provide a bending meshing type gear device which enables satisfactory torque detection.

According to the present invention, there is provided a bending meshing type gear device according to claims <NUM>-<NUM>.

According to the present invention, it is possible to provide a bending meshing type gear device which enables satisfactory torque detection.

<FIG> is an axial sectional view illustrating a bending meshing type gear device <NUM> according to Embodiment <NUM> of the present invention.

In the following description, a direction parallel to a rotary axis O1 (to be described later) will be referred to as an axial direction, a direction along a circumference around the rotary axis O1 will be referred to as a circumferential direction, and a direction along a radius of the circumference around the rotary axis O1 will be referred to as a radial direction.

The bending meshing type gear device <NUM> according to Embodiment <NUM> is a speed reducer, for example. An application of the bending meshing type gear device <NUM> is not particularly limited, and various applications can be adopted. For example, the bending meshing type gear device <NUM> is used to drive a joint of a cooperative robot that carries out work in cooperation with a person. The bending meshing type gear device <NUM> includes a wave generator shaft <NUM>, a wave generator bearing <NUM>, a first external tooth portion <NUM>, a second external tooth portion <NUM>, a first internal tooth portion <NUM>, a second internal tooth portion <NUM>, a casing <NUM>, a first cover <NUM>, a second cover <NUM>, a third cover <NUM>, bearings <NUM> and <NUM>, a main bearing <NUM>, and stopper rings <NUM> and <NUM>.

The wave generator shaft <NUM> is a hollow cylindrical shaft that rotates around the rotary axis O1, and includes a wave generator 30A having a non-circular (for example, elliptical) outer shape in a cross section perpendicular to the rotary axis O1, and shaft portions 30B and 30C provided on both sides in the axial direction of the wave generator 30A. The elliptical shape does not need to be a geometrically exact elliptical shape, and includes a substantially elliptical shape. The shaft portions 30B and 30C are shafts having a circular outer shape in the cross section perpendicular to the rotary axis O1. The wave generator shaft <NUM> may be a solid shaft.

The first internal tooth portion <NUM> is configured so that teeth are provided in a portion of an inner periphery of a first internal tooth member <NUM> serving as a stiff internal gear.

The second internal tooth portion <NUM> is configured so that teeth are provided in a portion of an inner periphery of a stiff second internal tooth member <NUM>.

The first external tooth portion <NUM> and the second external tooth portion <NUM> are integrally provided so that one and the other are aligned in the axial direction in an outer periphery of one flexible metal cylindrical base portion <NUM>. The first external tooth portion <NUM>, the second external tooth portion <NUM>, and the base portion <NUM> form an external gear.

The first external tooth portion <NUM> meshes with the first internal tooth portion <NUM>, and the second external tooth portion <NUM> meshes with the second internal tooth portion <NUM>.

For example, the wave generator bearing <NUM> is a roller bearing, and is disposed between the wave generator 30A and the base portion <NUM> in which the first external tooth portion <NUM> and the second external tooth portion <NUM> are formed. The wave generator 30A, the first external tooth portion <NUM>, and the second external tooth portion <NUM> are relatively rotatable via the wave generator bearing <NUM>.

The wave generator bearing <NUM> includes an outer ring 31a fitted into the base portion <NUM>, a plurality of rolling elements (rollers) 31b, and a holder 31c for holding the plurality of rolling elements 31b.

The plurality of rolling elements 31b include a first group of the rolling elements 31b disposed inward in the radial direction of the first external tooth portion <NUM> and the first internal tooth portion <NUM> and aligned in the circumferential direction, and a second group of the rolling elements 31b disposed inward in the radial direction of the second external tooth portion <NUM> and the second internal tooth portion <NUM> and aligned in the circumferential direction. The rolling elements 31b roll on rolling surfaces by using an outer peripheral surface of the wave generator 30A and an inner peripheral surface of the outer ring 31a. The wave generator bearing <NUM> may have an inner ring separate from the wave generator 30A. In addition, the wave generator bearing <NUM> may not have the outer ring 31a, and an inner peripheral surface of the base portion <NUM> may be used as an outer ring-side rolling surface. A type of the rolling element is not particularly limited, and may be a ball, for example. In addition, the number of rows of the rolling elements is not limited to two. The number may be one row, or three or more rows.

The stopper rings <NUM> and <NUM> are disposed on both sides in the axial direction of the first external tooth portion <NUM>, the second external tooth portion <NUM>, and the wave generator bearing <NUM>, thereby restricting a movement of the first external tooth portion <NUM>, the second external tooth portion <NUM>, and the wave generator bearing <NUM> in the axial direction.

The casing <NUM> covers an outer peripheral side of the second internal tooth member <NUM>. An outer ring portion of the main bearing <NUM> is formed in an inner peripheral portion of the casing <NUM>, and rotatably supports the second internal tooth member <NUM> via the main bearing <NUM>. For example, the casing <NUM> is connected to the first internal tooth member <NUM> via a connection member such as a bolt.

For example, the main bearing <NUM> is a cross roller bearing, and includes a plurality of rolling elements disposed between an inner ring portion integrated with the second internal tooth member <NUM> and an outer ring portion integrated with the casing <NUM>. The main bearing <NUM> may be configured to include a plurality of bearings (angular ball bearings or tapered bearings) separated in the axial direction between the second internal tooth member <NUM> and the casing <NUM>.

In addition, an oil seal <NUM> is provided between the casing <NUM> and the second internal tooth member <NUM>, on an output side of the main bearing <NUM>, thereby suppressing an outflow of a lubricant flowing outward (to the output side) in the axial direction.

For example, the first cover <NUM> is connected to the third cover <NUM> via a connection member such as a bolt (not illustrated) , and, for example, the third cover <NUM> is connected to the first internal tooth member <NUM> and the casing <NUM> via a connection member such as a bolt (not illustrated).

The first cover <NUM> covers the first external tooth portion <NUM> and the first internal tooth portion <NUM> from a counter-output side in the axial direction. The first cover <NUM>, the third cover <NUM>, the first internal tooth member <NUM>, and the casing <NUM> are directly or indirectly connected to an external member (for example, a base end-side arm member of a cooperative robot).

For example, a side connected to the external member (also referred to as a mating member, for example, one member for transmitting power between main body devices in which the bending meshing type gear device <NUM> is incorporated as a component) to output a decelerated motion to the external member will be referred to as an output side. A side opposite to the output side in the axial direction will be referred to as a counter-output side. A bearing <NUM> is disposed between the first cover <NUM> and the shaft portion 30B of the wave generator shaft <NUM>, and the wave generator shaft <NUM> is rotatably supported by the first cover <NUM>. As the bearing <NUM>, a ball bearing is used as an example. However, other radial bearings may be used.

An oil seal <NUM> is provided between the first cover <NUM> and the shaft portion 30B of the wave generator shaft <NUM>, on the counter-output side of the bearing <NUM>, thereby suppressing an outflow of the lubricant flowing outward (to the counter-output side) in the axial direction.

For example, the second cover <NUM> is connected to the second internal tooth member <NUM> via a connection member <NUM> such as a bolt, and covers the second external tooth portion <NUM> and the second internal tooth portion <NUM> from the output side in the axial direction. The second cover <NUM> and the second internal tooth member <NUM> are connected to an external member (for example, a tip side arm member of the cooperative robot) that outputs a decelerated motion (the external member is a member that relatively rotates with respect to an external member to which the first internal tooth member <NUM> is connected).

A bearing <NUM> is disposed between the second cover <NUM> and the shaft portion 30C of the wave generator shaft <NUM>, and the wave generator shaft <NUM> is rotatably supported by the second cover <NUM>. As the bearing <NUM>, a ball bearing is used as an example. However, other radial bearings may be used.

An oil seal <NUM> is provided between the second cover <NUM> and the shaft portion 30C of the wave generator shaft <NUM>, on the output side of the bearing <NUM>, thereby suppressing an outflow of the lubricant flowing outward (to the output side) in the axial direction. The second cover <NUM> may be integrally formed with the second internal tooth member <NUM>.

Furthermore, a sealing O-ring <NUM> is interposed between the first internal tooth member <NUM> and the casing <NUM>.

Similarly, a sealing O-ring <NUM> is interposed between the first internal tooth member <NUM> and the third cover <NUM>, a sealing O-ring <NUM> is interposed between the third cover <NUM> and the first cover <NUM>, and a sealing O-ring <NUM> is interposed between the second internal tooth member <NUM> and the second cover <NUM>.

Therefore, an internal space of the bending meshing type gear device <NUM> (space where a meshing portion between the first external tooth portion <NUM> and the first internal tooth portion <NUM>, a meshing portion between the second external tooth portion <NUM> and the second internal tooth portion <NUM>, the main bearing <NUM>, the bearings <NUM> and <NUM>, the wave generator bearing <NUM> are present) is a lubricant filling space to be filled with the lubricant, and is hermetically sealed with the oil seals <NUM> to <NUM> and the O-rings <NUM> to <NUM>.

<FIG> is a perspective view of the first internal tooth member <NUM>. As illustrated, the first internal tooth member <NUM> includes an internal tooth ring portion <NUM>, an inner periphery of which has an internal tooth of the first internal tooth portion <NUM>, an external connection portion <NUM> connected to an external member together with the casing <NUM> and the third cover <NUM>, and an easily deformable portion <NUM> which is provided between the internal tooth ring portion <NUM> and the external connection portion <NUM> in the radial direction, and which is more easily deformable (which has a larger deformation amount) than the internal tooth ring portion <NUM> when a torque acts on the first internal tooth member <NUM>.

The internal tooth ring portion <NUM> has a ring shape, and the first internal tooth portion <NUM> (internal tooth) is formed on an inner peripheral surface thereof.

The external connection portion <NUM> has a ring shape, and is located in the outermost periphery of the first internal tooth member <NUM>. A plurality of attachment holes penetrating in the axial direction are formed for the external member at a constant interval in the circumferential direction. The external connection portion <NUM> may be directly connected to the external member, or may be connected to the external member via the first cover <NUM> or the third cover <NUM>.

The easily deformable portion <NUM> is configured to include a plurality of pillar members <NUM> intermittently provided in the circumferential direction between the internal tooth ring portion <NUM> and the external connection portion <NUM>.

The pillar member <NUM> extends outward in the radial direction from an outer periphery of the internal tooth ring portion <NUM>, and is connected to an inner periphery of the external connection portion <NUM>. Here, a case where the easily deformable portion <NUM>, the internal tooth ring portion <NUM>, and the external connection portion <NUM> are integrally formed of the same material (for example, a metal material or a resin material) will be described as an example.

In addition, a case where four pillar members <NUM> are provided at a constant interval in the circumferential direction will be described as an example. It is preferable that the interval between the respective pillar members <NUM> in the circumferential direction is uniform. However, this configuration is not essential. In addition, the number of the pillar members <NUM> can be increased or decreased.

The external connection portion <NUM> and the pillar member <NUM> have the same width (thickness) in the axial direction, and have a narrower axial width than that of the internal tooth ring portion <NUM>. The pillar member <NUM> may have an axial width different from that of the external connection portion <NUM>. For example, when intensity for ensuring a torque transmission function is sufficient, the pillar member <NUM> may have an axial width smaller than that of the external connection portion <NUM>. In addition, the pillar member <NUM> may have a recessed portion for accommodating the distortion gauge <NUM>.

A projection 413a projecting to the output side is formed over the entire circumferential direction on an output side flat surface inside the external connection portion <NUM> in the radial direction, and is fitted (spigot fitted) into a counter-output side recessed portion of the casing <NUM>.

The distortion gauge <NUM> serving as distortion measurement means is attached to each of the pillar members <NUM>. A case where the distortion gauge <NUM> is attached to a surface on the counter-output side in the pillar member <NUM> will be described as an example. However, the distortion gauge <NUM> may be attached to a surface on the output side, or may be attached to a surface on a side in one end portion or the other end portion in the circumferential direction.

As an example, a case will be described where the distortion gauge <NUM> is attached to the pillar member <NUM> in a direction in which expansion-contraction distortion of the pillar member <NUM> is detected in the radial direction. The direction in which the distortion is detected by the distortion gauge <NUM> is not limited to the radial direction.

The easily deformable portion <NUM> (pillar member <NUM>) is more significantly deformed than the internal tooth ring portion <NUM>, when a torque acts on the first internal tooth member <NUM> (specifically, in a state where the external connection portion <NUM> is connected to the external member, when the first internal tooth portion <NUM> receives a meshing reaction force so that a torque acts on the first internal tooth member <NUM>). As a result, the expansion-contraction distortion in the radial direction which occurs in the pillar member <NUM> increases. The distortion of the pillar member <NUM> has a correlation with the torque. Accordingly, the torque can be acquired by causing the distortion gauge <NUM> to detect the distortion.

As illustrated in <FIG>, each of the distortion gauges <NUM> is connected to the measurement device <NUM> (although <FIG> illustrates a state where only one distortion gauge <NUM> is connected, all of the distortion gauges <NUM> are actually connected).

The measurement device <NUM> amplifies and records a detection signal of each of the distortion gauges <NUM>. In addition, in the measurement device <NUM>, a rotation phase of the wave generator 30A is input from a detection unit (not illustrated).

For example, the measurement device <NUM> has a data table in which the rotation phase of the wave generator shaft <NUM> and a detection value and a torque value of each of the distortion gauges <NUM> are associated with each other. The measurement device <NUM> specifies the rotation phase input from the detection unit and the torque value corresponding to the detection value of each of the distortion gauges <NUM> with reference to the data table. For example, the data table is prepared in advance by an experiment. Specifically, the data table is prepared by acquiring the detection value of each of the distortion gauges <NUM> while changing the rotation phase of the wave generator 30A and the torque applied to the first internal tooth member <NUM>. A method for causing the measurement device <NUM> to specify the torque from the detection value of each of the distortion gauges <NUM> is not particularly limited, and for example, a configuration may be adopted so that the torque value is calculated by calculating the torque value with a calculation expression prepared in advance.

When a rotary motion is input from a motor (not illustrated) and the wave generator shaft <NUM> rotates, the motion of the wave generator 30A is transmitted to the first external tooth portion <NUM> and the second external tooth portion <NUM>. In this case, the first external tooth portion <NUM> and the second external tooth portion <NUM> are restricted to a shape formed along an outer peripheral surface of the wave generator 30A, and are bent in an elliptical shape having a major axis portion and a minor axis portion when viewed in the axial direction. Furthermore, the first external tooth portion <NUM> meshes with the first internal tooth portion <NUM> of the fixed first internal tooth member <NUM> in the major axis portion. Therefore, the first external tooth portion <NUM> and the second external tooth portion <NUM> do not rotate at the same rotation speed as that of the wave generator 30A. The wave generator 30A relatively rotates inside the first external tooth portion <NUM> and the second external tooth portion <NUM>. As a result of the relative rotation, the first external tooth portion <NUM> and the second external tooth portion <NUM> are flexibly deformed so that a major axis position and a minor axis position are moved in the circumferential direction. A period of the deformation is proportional to a rotation period of the wave generator shaft <NUM>.

When the first external tooth portion <NUM> and the second external tooth portion <NUM> are flexibly deformed, the major axis positions are moved. In this manner, a meshing position between the first external tooth portion <NUM> and the first internal tooth portion <NUM> is changed in a rotation direction. Here, it is assumed that the number of teeth of the first external tooth portion <NUM> is set to <NUM> and the number of teeth of the first internal tooth portion <NUM> is set to <NUM>. In this case, each time the meshing position rotates once, meshing teeth of the first external tooth portion <NUM> and the first internal tooth portion <NUM> are shifted from each other. In this manner, the first external tooth portion <NUM> rotates (revolves). When the number of teeth is set as described above, the rotary motion of the wave generator shaft <NUM> is decelerated at a reduction ratio of <NUM>:<NUM>, and is transmitted to the first external tooth portion <NUM>.

Meanwhile, the second external tooth portion <NUM> having the base portion <NUM> in common with the first external tooth portion <NUM> meshes with the second internal tooth portion <NUM>. Accordingly, due to the rotation of the wave generator shaft <NUM>, the meshing position between the second external tooth portion <NUM> and the second internal tooth portion <NUM> is also changed in the rotation direction. Meanwhile, the number of teeth of the second internal tooth portion <NUM> and the number of teeth of the second external tooth portion <NUM> coincide with each other. Accordingly, the second external tooth portion <NUM> and the second internal tooth portion <NUM> do not relatively rotate. The rotary motion of the second external tooth portion <NUM> is transmitted to the second internal tooth portion <NUM> at a reduction ratio of <NUM>:<NUM>. For these reasons, the rotary motion of the wave generator shaft <NUM> is decelerated at a reduction ratio of <NUM>:<NUM>, and is transmitted to the second internal tooth member <NUM> and the second cover <NUM>. The decelerated rotary motion is output to the external member.

In the deceleration operation, in the first internal tooth portion <NUM>, the torque is transmitted from the internal tooth ring portion <NUM> to the external connection portion <NUM> via the easily deformable portion <NUM>.

In this case, in each of the pillar members <NUM> of the easily deformable portion <NUM>, the radial distortion detected by the distortion gauge <NUM> provided in each of the pillar members <NUM> is input to the measurement device <NUM>, and the torque value based on the distortion is derived.

For example, the torque value acquired by the configurations is input to a control device of the main body device in which the bending meshing type gear device <NUM> is incorporated as a component, and can be used to detect occurrence of an abnormality of the torque value in the control device. For example, when the bending meshing type gear device <NUM> is incorporated in a joint of a cooperative robot, the contact between a robot arm and a person is detected by using an abnormal increase in the torque value, and a stopping operation or an avoiding operation of the robot can be performed.

As described above, according to the bending meshing type gear device <NUM> of the present embodiment, the first internal tooth member <NUM> includes the easily deformable portion <NUM> configured to be more easily deformable than the internal tooth ring portion <NUM>, and the distortion gauge <NUM> provided in the easily deformable portion <NUM>.

Therefore, when the torque is transmitted, the first internal tooth member <NUM> can detect the distortion in the easily deformable portion <NUM> which is more easily deformable than the internal tooth ring portion <NUM> inside the external connection portion <NUM>. Therefore, the distortion gauge <NUM> can more accurately and satisfactorily detect the torque by detecting the distortion at a position where the distortion caused by the torque is likely to occur.

In addition, when the distortion is detected in the outer peripheral portion where the distortion caused by the torque is unlikely to occur, in order to improve detection accuracy, it is necessary to take measures for forming the first internal tooth member of a non-hard material as a whole so that the distortion caused by the torque is likely to occur in the outer peripheral portion. However, the measures have a disadvantage in that gear meshing errors are likely to occur.

In contrast, in the first internal tooth member <NUM> of the bending meshing type gear device <NUM> of the present embodiment, only a portion having the easily deformable portion <NUM> needs to be easily deformed. Therefore, occurrence of the gear meshing errors can be suppressed.

In addition, the distortion gauge <NUM> is installed inside the bending meshing type gear device <NUM> instead of the outer periphery of the bending meshing type gear device <NUM>. Therefore, the device can be miniaturized.

In addition, the easily deformable portion <NUM> is configured to include the pillar members <NUM> intermittently provided in the circumferential direction between the internal tooth ring portion <NUM> and the external connection portion <NUM>. Therefore, a special method for adding a new member is not required, and a configuration serving as the easily deformable portion <NUM> can be easily realized.

<FIG> is a front view when another example of a first internal tooth member of a bending meshing type gear device according to Embodiment <NUM> of the present invention is viewed in the axial direction.

A first internal tooth member 41A of Embodiment <NUM> has a different number of the pillar members <NUM> forming an easily deformable portion 414A, compared to the above-described first internal tooth member <NUM>. That is, the easily deformable portion 414A of the first internal tooth member 41A includes eight pillar member <NUM> provided at a uniform interval in the circumferential direction. A structure and dimensions of every pillar member <NUM> are the same as those of the pillar member <NUM> of the above-described first internal tooth member <NUM>.

The distortion gauge <NUM> is individually attached to each of the pillar members <NUM>.

In this way, in the first internal tooth member 41A, the internal tooth ring portion <NUM> can be supported from the outside by increasing the number of the pillar members <NUM>, and bending of the internal tooth ring portion <NUM> can be suppressed. In this manner, the gear meshing errors can be reduced.

In addition, the number of the distortion gauges <NUM> can be increased.

A first internal tooth member 41B of Embodiment <NUM> is different from the above-described first internal tooth member <NUM> in that the first internal tooth member 41B includes four support members 418B.

Each of the support members 418B is provided between the internal tooth ring portion <NUM> and the external connection portion <NUM> in the radial direction, and is provided between two pillar member <NUM> adjacent to each other in the circumferential direction.

As illustrated in <FIG>, each of the support members 418B extends to bridge in the radial direction between the internal tooth ring portion <NUM> and the external connection portion <NUM>. One end portion thereof, for example, the internal tooth ring portion <NUM> side is fixed, and the other end portion, for example, the external connection portion <NUM> side is in sliding contact with or slidable on the inner periphery of the external connection portion <NUM>. The external connection portion <NUM> side may be fixed, and the internal tooth ring portion <NUM> side may be in sliding contact or slidable.

Each of the support members 418B is configured to include a member separate from the internal tooth ring portion <NUM> and the external connection portion <NUM>, and one end portion side is fixed by welding, adhesion, or other joining methods. Each of the support members 418B may be fixed to the internal tooth ring portion <NUM> or the external connection portion <NUM> at least in the circumferential direction. In addition, each of the support members 418B may be formed of a material different from that of the first internal tooth member <NUM>, such as a resin, or may be formed of the same material.

In this way, in the first internal tooth member 41B, the internal tooth ring portion <NUM> can be supported from the outside by providing the support member 418B, and bending of the internal tooth ring portion <NUM> can be suppressed. In this manner, the gear meshing errors can be reduced.

Furthermore, only one end portion side of the support member 418B is fixed to the external connection portion <NUM> or the internal tooth ring portion <NUM> in the circumferential direction, and the other end portion is not fixed. Therefore, while the internal tooth ring portion <NUM> is supported from the outside, the expansion-contraction distortion of the pillar member <NUM> caused by the torque is not suppressed. Therefore, the torque can be satisfactorily detected.

In the above-described first internal tooth member <NUM>, the easily deformable portion <NUM> is configured to include the four pillar members <NUM> straightly extending in the radial direction. However, the present invention is not limited thereto.

A first internal tooth member 41C of Embodiment <NUM> includes a plurality of bearing portions 415C in which an easily deformable portion 414C connects the internal tooth ring portion <NUM> and the external connection portion <NUM> in the radial direction and the circumferential direction.

The plurality of bearing portions 415C are provided at a uniform interval in the circumferential direction between the internal tooth ring portion <NUM> and the external connection portion <NUM>. Each of the bearing portions 415C may be integrally formed of a material the same as that of the internal tooth ring portion <NUM> and the external connection portion <NUM>, or may be formed of a different material. In addition, both end portions of each of the bearing portions 415C are fixed to the internal tooth ring portion <NUM> and the external connection portion <NUM>. In addition, here, a case where four bearing portions 415C are provided will be described as an example. However, the number may be two or more, and the number is not limited to four. In Embodiment <NUM>, each of the bearing portions 415C corresponds to the pillar member.

Each of the bearing portions 415C has a crank shape. That is, each of the bearing portions 415C includes a first extending portion 415Ca extending outward in the radial direction from the outer periphery of the internal tooth ring portion <NUM>, a second extending portion 415Cb extending inward in the radial direction from the inner periphery of the external connection portion <NUM>, and an intermediate connection portion 415Cc connecting an extending end portion of the first extending portion 415Ca and an extending end portion of the second extending portion 415Cb and provided along the circumferential direction or a tangential direction with respect to the circumferential direction.

The distortion gauge <NUM> is attached in a direction in which the expansion-contraction distortion is detected in the longitudinal direction of the intermediate connection portion 415Cc, in the intermediate connection portion 415Cc of each of the bearing portions 415C.

In this way, in the first internal tooth member 41C, the distortion gauge <NUM> is provided in the intermediate connection portion 415Cc of the bearing portion 415C having the intermediate connection portion 415Cc which is a portion provided along the circumferential direction or the tangential direction with respect to the circumferential direction.

In this manner, when the torque is transmitted in the bending meshing type gear device, in the intermediate connection portion 415Cc which is a portion provided along the circumferential direction or the tangential direction with respect to the circumferential direction, the expansion-contraction distortion more significantly occurs. Therefore, the torque can be more accurately detected.

A first internal tooth member 41D of Embodiment <NUM> includes a plurality of bearing portions 415D in which an easily deformable portion 414D is fixed to the outer periphery of the internal tooth ring portion <NUM> and extends in the tangential direction with respect to the circumferential direction.

Both end portions of each of the bearing portions 415D are fixed to the inner periphery of the external connection portion <NUM>, and an intermediate portion thereof is fixed to the outer periphery of the internal tooth ring portion <NUM>.

Here, a case where four bearing portions 415D are provided will be described as an example. Both end portions of the four bearing portions 415D are connected to end portions of the other bearing portions 415D, and the four bearing portions 415D are integrally formed to have a square frame shape when viewed in the axial direction.

Furthermore, in each of the bearing portions 415D, the distortion gauges <NUM> are attached one by one between each end portion fixed to the inner periphery of the external connection portion <NUM> and an intermediate portion fixed to the outer periphery of the internal tooth ring portion <NUM>. Each of the distortion gauges <NUM> is attached in a direction in which the expansion-contraction distortion in the longitudinal direction of the bearing portion 415D is detected.

Each of the bearing portions 415D may be integrally formed of a material the same as that of the internal tooth ring portion <NUM> and the external connection portion <NUM>, or may be formed of a different material.

In addition, here, a case where four bearing portions 415D are provided will be described as an example. However, the number is not limited to four as long as the internal tooth ring portions <NUM> can be surrounded at a uniform interval in the circumferential direction.

In this way, in the first internal tooth member 41D, the easily deformable portion 414D is configured to include the bearing portion 415D having the above-described structure. However, the easily deformable portion 414D can also more accurately and satisfactorily detect the torque, as in the easily deformable portion <NUM>.

<FIG> is a perspective view illustrating another example of a first internal tooth member of a bending meshing type gear device according to Embodiment <NUM> of the present invention.

In the above-described first internal tooth member <NUM>, the easily deformable portion <NUM> is configured to include the four pillar members <NUM> intermittently disposed in the circumferential direction. However, the configuration is not limited thereto.

In the first internal tooth member 41E of Embodiment <NUM>, an easily deformable portion 414E is formed to have a ring-shaped flat plate which is continuous in the circumferential direction between the internal tooth ring portion <NUM> and the external connection portion <NUM>.

However, as illustrated in the axial sectional view in <FIG>, an axial thickness d3 of the easily deformable portion 414E is set to be smaller than any of an axial thickness d1 of the internal tooth ring portion <NUM> and an axial thickness d2 of the external connection portion <NUM>.

The plurality of distortion gauges <NUM> are attached onto any flat surface of the easily deformable portion 414E at a uniform interval in the circumferential direction. Here, a case where the four distortion gauges <NUM> are provided will be described as an example. The number of the distortion gauges <NUM> may be one, and for example, a ring-shaped distortion gauge may be disposed along a ring shape of the easily deformable portion 414E.

Each of the distortion gauges <NUM> is attached in a direction in which the expansion-contraction distortion along the radial direction is detected.

In this way, in the first internal tooth member 41E, the easily deformable portion 414E has a flat plate shape which is continuous in the circumferential direction. The axial thickness d3 is set to be smaller than the axial thickness d1 of the internal tooth ring portion <NUM> and the axial thickness d2 of the external connection portion <NUM>. Therefore, the easily deformable portion 414E is more likely to be deformed than the internal tooth ring portion <NUM> when the torque is transmitted in the bending meshing type gear device. As a result, the expansion-contraction distortion is likely to occur along the radial direction. As in the easily deformable portion <NUM>, the easily deformable portion 414E can also more accurately and satisfactorily detect the torque. The axial thickness d3 of the easily deformable portion 414E may be smaller than at least the axial thickness d1 of the internal tooth ring portion <NUM>, and may be equal to the axial thickness d2 or larger than the axial thickness d2 of the external connection portion <NUM>.

In addition, the easily deformable portion 414E is continuous in the circumferential direction. Therefore, the internal tooth ring portion <NUM> can be supported from the outside over the entire circumference, and bending of the internal tooth ring portion <NUM> can be suppressed. In this manner, the gear meshing errors can be reduced.

<FIG> is an axial sectional view of a first internal tooth member according to Embodiment <NUM> of the present invention.

In each of the above-described embodiments, the shape of the easily deformable portion <NUM> is devised so that the easily deformable portion <NUM> is more easily deformable than the internal tooth ring portion <NUM>. However, a method for making the easily deformable portion <NUM> easily deformable is not particularly limited. For example, as in the first internal tooth member 41F illustrated in <FIG>, an easily deformable portion 414F may be more easily deformable than the internal tooth ring portion <NUM> by using a softer material than that of the internal tooth ring portion <NUM> and further that of the external connection portion <NUM>. For example, it is preferable that the easily deformable portion 414F is formed of a metal material softer than that of the internal tooth ring portion <NUM> and the external connection portion <NUM>, or a softer resin material.

In this case, the axial thicknesses of the internal tooth ring portion <NUM>, the easily deformable portion 414F, and the external connection portion <NUM> may be the same as each other. Alternatively, the easily deformable portion 414F may be thicker than the internal tooth ring portion <NUM> or the external connection portion <NUM>.

In addition, the easily deformable portions 414F may be intermittent, or may be continuous along the circumferential direction. When the easily deformable portions 414F are intermittent, the easily deformable portions 414F may have a form the same as that of the above-described easily deformable portions <NUM>, 414A, 414C, and 414D. Furthermore, the above-described support member 418B may be added.

<FIG> is a front view illustrating another example of a first internal tooth member of a bending meshing type gear device according to Embodiment <NUM> of the present invention. In <FIG>, the first external tooth portion <NUM> is simply illustrated by an ellipse indicating the major axis position.

In the above-described first internal tooth member <NUM>, the easily deformable portion <NUM> includes two sets, one set having two pillar members <NUM> individually provided on both sides of the first internal tooth member <NUM> in the radial direction. The four pillar members <NUM> configured to include the two sets are provided at a uniform interval in the circumferential direction, and the distortion gauges <NUM> are attached to all of the pillar members <NUM>.

In contrast, in the bending meshing type gear device according to Embodiment <NUM>, an easily deformable portion <NUM> of a first internal tooth member <NUM> is the same as the first internal tooth member <NUM> in the following points. The easily deformable portion <NUM> of the first internal tooth member <NUM> includes two sets, one set having two pillar members <NUM> provided on both sides of the first internal tooth member <NUM> in the radial direction. The respective pillar members <NUM> are provided at a uniform interval in the circumferential direction. In the first internal tooth member <NUM>, distortion gauges <NUM>-<NUM> and <NUM>-<NUM> are provided in only one set each having two pillar members <NUM>.

The distortion gauge <NUM>-<NUM> and the distortion gauge <NUM>-<NUM> have the same structure. When both gauges do not need to be distinguished from each other in the following description, both gauges will be referred to as a distortion gauge <NUM>.

In addition, distortion gauges <NUM>-<NUM> and <NUM>-<NUM> illustrated by a two-dot chain line in <FIG> are other examples of the first internal tooth member (to be described later), and the first internal tooth member <NUM> of Embodiment <NUM> is not provided with the distortion gauges <NUM>-<NUM> and <NUM>-<NUM>.

<FIG> is a plan view of the distortion gauge <NUM>. As illustrated in the drawing, the distortion gauge <NUM> is a double shearing type distortion gauge, and includes measurement units 56A and 56B individually formed on the left and right sides in <FIG> on a plane of an insulator substrate.

Each of the measurement units 56A and 56B includes grid portions 561A and 561B in which resistance wires are folded back in parallel in multiple layers, and leads 562A and 562B extending from both end portions of the grid portions 561A and 561B.

The resistance wire of the grid portion 561A of the measurement unit 56A on the left side in <FIG> extends obliquely rightward in a downward direction, and the resistance wire of the grid portion 561B of the measurement unit 56B on the right side extends obliquely leftward in the downward direction.

As can be understood from this structure, the distortion gauge <NUM> substantially includes two distortion gauges having different distortion detection directions, and has a structure which can individually obtain a detection signal from the two distortion gauges.

Each of the measurement units 56A and 56B has a structure which is highly sensitive to the contraction distortion in a direction along a wire extending direction of the respective grid portions 561A and 561B. The wire extending direction of the grid portion 561A of the measurement unit 56A and the wire extending direction of the grid portion 561B of the measurement unit 56B are perpendicular to each other.

In the distortion gauge <NUM>, a direction in which the respective wire extending directions of the grid portions 561A and 561B of the two measurement units 56A and 56B are combined is set as a reference direction (arrow G in <FIG>). The distortion gauge <NUM> is attached to the pillar member <NUM> so that a reference direction G is perpendicular to a direction in which a shearing force is generated with respect to the pillar member <NUM> during an operation of the bending meshing type gear device <NUM>. More specifically, the reference direction G of the distortion gauge <NUM> is provided to be parallel to the longitudinal direction of the pillar member <NUM>, that is, the radial direction.

In the above-described case, when the first external tooth portion <NUM> relatively rotates in a counterclockwise direction with respect to the first internal tooth member <NUM> due to rotation of the wave generator shaft <NUM> in a clockwise direction, (hereinafter, referred to as during forward rotation), the internal tooth ring portion <NUM> of the first internal tooth member <NUM> receives a torque in the clockwise direction with respect to the external connection portion <NUM>. A shearing force generated by this operation mainly acts on the grid portion 561A of the measurement unit 56A, and a detection signal corresponding to the torque can be obtained from the measurement unit 56A.

In addition, when the first external tooth portion <NUM> relatively rotates in the clockwise direction with respect to the first internal tooth member <NUM> due to the rotation of the wave generator shaft <NUM> in the counterclockwise direction (hereinafter, referred to as during rearward rotation). , the internal tooth ring portion <NUM> of the first internal tooth member <NUM> receives a torque in the counterclockwise direction with respect to the external connection portion <NUM>. A shearing force generated by this operation mainly acts on the grid portion 561B of the measurement unit 56B, and a detection signal corresponding to the torque can be obtained from the measurement unit 56B.

The first internal tooth member <NUM> has a structure in which one end portion and the other end portion in the radial direction of the pillar members <NUM>, one set having two pillar members <NUM>, are symmetrical. In this case, when the bending meshing type gear device <NUM> is operated, as long as a bending moment in the axial direction is not generated, in both the one pillar member <NUM> and the other pillar member <NUM>, one set having two pillar members <NUM>, the shearing forces generated by the torque are equally generated.

Therefore, even when the distortion gauges <NUM> are not provided on both the pillar members <NUM>, one set having two pillar members <NUM>, when the distortion gauge <NUM> is provided on only one of the pillar members <NUM>, a required distortion can be detected, and the torque can be obtained from detection of the respective distortion gauges <NUM>.

That is, the bending meshing type gear device <NUM> of Embodiment <NUM> can particularly preferably obtain the torque when in use in an environment where the bending moment in the axial direction is unlikely to be generated.

<FIG> illustrates a Wheatstone bridge circuit <NUM> configured in a measurement device using each of the above-described distortion gauges <NUM>.

The Wheatstone bridge circuit <NUM> includes first to fourth paths <NUM> to <NUM>.

Both one end portion of the first path <NUM> and one end portion of the second path <NUM> are connected to a positive electrode side of a voltage supply source and a positive electrode side of a transmitter. In addition, both one end portion of the third path <NUM> and one end portion of the fourth path <NUM> are connected to a negative electrode side of the voltage supply source and a negative electrode side of the transmitter.

Furthermore, the other end portion of the first path <NUM> and the other end portion of the third path <NUM> are connected, and a connection point thereof serves a positive electrode side output of the detection signal. In addition, the other end portion of the second path <NUM> and the other end portion of the fourth path <NUM> are connected, and a connection point thereof serves as a negative electrode side output of the detection signal.

As illustrated in <FIG>, the first path <NUM> is provided with the measurement unit 56A ("2A" in <FIG>) of the distortion gauge <NUM>-<NUM>, and the second path <NUM> is provided with the measurement unit 56B ("2B" in <FIG>) of the distortion gauge <NUM>-<NUM>. The third path <NUM> is provided with the measurement unit 56B ("1B" in <FIG>) of the distortion gauge <NUM>-<NUM>, and the fourth path <NUM> is provided with the measurement unit 56A ("1A" in <FIG>) of the distortion gauge <NUM>-<NUM>.

In a case of <FIG>, "3A", "3B", "4A", and "4B" illustrated by a two-dot chain line indicate the respective measurement units 56A and 56B of the distortion gauges <NUM>-<NUM> and, <NUM>-<NUM> in another example of the first internal tooth member (to be described later), and the Wheatstone bridge circuit <NUM> of Embodiment <NUM> is not provided with "3A" , "3B", "4A", and "4B".

In the above-described Wheatstone bridge circuit <NUM>, during the forward rotation of the first external tooth portion <NUM>, the measurement unit 56A of the distortion gauge <NUM>-<NUM> and the measurement unit 56A of the distortion gauge <NUM>-<NUM> can respectively obtain a detection signal in accordance with the movement at the major axis position of the wave generator 30A. The detection signal is obtained from a potential difference between the positive electrode side output and the negative electrode side output of the Wheatstone bridge circuit <NUM>. The detection signal based on a shearing distortion detected from the respective pillar members <NUM> correlates with the torque of the bending meshing type gear device. Therefore, the torque of the bending meshing type gear device can be obtained from the detection signal based on the shearing distortion.

As described above, in the bending meshing type gear device according to Embodiment <NUM>, the number of the distortion gauges <NUM> can be reduced, compared to the number of the pillar member <NUM>, and production costs of the device can be reduced.

In Embodiment <NUM>, a case where the easily deformable portion <NUM> of the first internal tooth member <NUM> has two sets of (four) pillar members <NUM> has been described as an example. However, a configuration having one set or three or more sets of pillar members <NUM> may be adopted.

In addition, the double shearing type distortion gauge has been described as an example of the distortion gauge <NUM>. However, it is also possible to use the distortion gauge <NUM> which detects the distortion in the longitudinal direction (radial direction) of the above-described pillar member <NUM>.

In addition, it is also possible to use the distortion gauge <NUM> instead of the distortion gauge <NUM> in each of the above-described embodiments <NUM> to <NUM>.

In addition, in Embodiment <NUM>, the double shearing type distortion gauge has been described as an example. However, for example, when being in an environment in which the bending meshing type gear device is used only by either the forward rotation or the rearward rotation, the distortion gauge having only any one of the measurement units 56A and 56B may be used.

In addition, when the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> are provided in all of the pillar members <NUM> as Embodiment <NUM>, as illustrated by two-dot chain lines in <FIG> and <FIG>, the measurement unit 56A ("2A" in <FIG>) of the distortion gauge <NUM>-<NUM> and the measurement unit 56A ("4A" in <FIG>) of the distortion gauge <NUM>-<NUM> are provided in series in the first path <NUM> of the Wheatstone bridge circuit <NUM>.

In addition, the measurement unit 56B ("2B" in <FIG>) of the distortion gauge <NUM>-<NUM> and the measurement unit 56B ("4B" in <FIG>) of the distortion gauge <NUM>-<NUM> are provided in series in the second path <NUM>.

In addition, the measurement unit 56B ("1B" in <FIG>) of the distortion gauge <NUM>-<NUM> and the measurement unit 56B ("3B" in <FIG>) of the distortion gauge <NUM>-<NUM> are provided in series on the third path <NUM>.

In addition, the measurement unit 56A ("1A" in <FIG>) of the distortion gauge <NUM>-<NUM> and the measurement unit 56A ("3A" in <FIG>) of the distortion gauge <NUM>-<NUM> are provided in series on the fourth path <NUM>.

In this manner, it is possible to obtain the torque of the bending meshing type gear device from the detection signal based on the shearing distortion detected from the respective pillar members <NUM>.

<FIG> is a simplified view illustrating another example of a first internal tooth member of a bending meshing type gear device according to Embodiment <NUM> of the present invention. In a case of <FIG>, the first external tooth portion <NUM> is also simply illustrated by an ellipse indicating the major axis position.

In Embodiment <NUM> described above, the configuration in which the easily deformable portion <NUM> has an even number of the pillar members <NUM> provided at a uniform interval in the circumferential direction has been described as an example.

In contrast, in a first internal tooth member <NUM> of the bending meshing type gear device according to Embodiment <NUM>, a configuration in which a plurality of the easily deformable portions <NUM> and an odd number of the pillar members <NUM> are provided at a uniform interval in the circumferential direction will be described as an example. In Embodiment <NUM>, a case where seven pillar members <NUM> are provided will be described as an example. However, the number of the pillar members <NUM> can be changed in any desired way as long as a plurality of the pillar members <NUM> and the odd number of the pillar members <NUM> are provided.

All of the pillar members <NUM> are provided with the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> the same as the above-described distortion gauges <NUM> in order in the circumferential direction.

When the number of the pillar members <NUM> of the first internal tooth member <NUM> is the odd number, as illustrated by a solid line in <FIG>, in a case of meshing at a position where one end portion of the major axis of the first external tooth portion <NUM> coincides with any of the pillar members <NUM> in the circumferential direction, the other end portion of the major axis of the first external tooth portion <NUM> meshes at an intermediate position between the other two pillar members <NUM>.

In this case, on one end portion side of the major axis of the first external tooth portion <NUM>, the shearing distortion occurring in the first internal tooth member <NUM> decreases due to stiffness of the pillar member <NUM>, and the shearing distortion occurring in the first internal tooth member <NUM> increase on the other end portion side of the major axis of the first external tooth portion <NUM>.

Here, among the distortion gauges <NUM>-<NUM> to <NUM>-<NUM>, the distortion gauge which detects the distortion is mainly the distortion gauge located near the major axis of the first external tooth portion <NUM>. In a case of the example illustrated by the solid line in <FIG>, the distortion is detected by <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. However, the distortion gauges <NUM>-<NUM> and <NUM>-<NUM> are separated from the major axis. Therefore, the distortion is slightly detected. As described above, on the other end portion side of the major axis of the first external tooth portion <NUM>, the shearing distortion occurring in the first internal tooth member <NUM> increases. Therefore, detection values of the distortion gauges <NUM>-<NUM> and <NUM>-<NUM> increase. On the other hand, on the one end portion side of the major axis of the first external tooth portion <NUM>, the shearing distortion occurring in the first internal tooth member <NUM> decreases. Therefore, a detection value of the distortion gauge <NUM>-<NUM> decreases, compared to the distortion gauges <NUM>-<NUM> and <NUM>-<NUM>. However, the measurement is performed through a Wheatstone bridge circuit <NUM> (refer to <FIG> to be described later) in which the respective measurement units 56A are connected in series and the respective measurement units 56B are connected in series. Therefore, detection signals are averaged in one end portion and the other end portion of the major axis of the first external tooth portion <NUM> (by summing up outputs of all of the distortion gauges), and an approximately medium detection signal is output.

In addition, as illustrated by a two-dot chain line in <FIG>, in a case of meshing at a position where all of both end portions of the major axis of the first external tooth portion <NUM> do not coincide with the respective pillar members <NUM> or are close to the pillar member <NUM> in the circumferential direction, the shearing distortion occurring in the first internal tooth member <NUM> on both one end side and the other end side of the major axis of the first external tooth portion <NUM> is approximately medium.

Therefore, when the detection values of the respective distortion gauges <NUM>-<NUM> to <NUM>-<NUM> are summed up, the approximately medium detection signal is also output.

Therefore, the plurality of pillar members and the odd number of pillar members are provided. In this manner, a fluctuation range (of a total value or an average value) of the detection signals obtained from the respective distortion gauges <NUM>-<NUM> to <NUM>-<NUM> decreases when the major axis of the first external tooth portion <NUM> rotationally moves in the circumferential direction. To cope with this result, the Wheatstone bridge circuit <NUM> configured in the measurement device using the above-described respective distortion gauges <NUM>-<NUM> to <NUM>-<NUM> is configured as illustrated in <FIG>.

In <FIG>, "1A" to "7A" respectively indicate the measurement units 56A of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM>, and "1B" to "7B" respectively indicate the measurement units 56B of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM>.

As illustrated in <FIG>, a resistor R1 is provided in the first path <NUM>, and a resistor R2 is provided in the second path <NUM>. The respective measurement units 56A of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> are connected in series, and are provided in the third path <NUM>. The respective measurement units 56B of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> are connected in series, and are provided in the fourth path <NUM>.

The resistors R1 and R2 are equal to resistance values of the seven measurement units 56A connected in series when no distortion occurs (also equal to resistance values of the seven measurement units 56B connected in series).

In this way, in the Wheatstone bridge circuit <NUM>, the respective measurement units 56A or the respective measurement units 56B of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> are connected in series, and are disposed in any path of the four paths <NUM> to <NUM>.

Therefore, when the major axis of the first external tooth portion <NUM> rotationally moves in the circumferential direction, even when an individual detection signal obtained from each of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> decreases, the respectively summed-up detection signal can be obtained, and the detection signal can be increased. In addition, since the plurality of pillar members and the odd number of pillar members are provided, it is possible to reduce variations in (the total value of) the detection signal caused by the position in the circumferential direction of the major axis of the first external tooth portion <NUM>.

In addition, as the Wheatstone bridge circuit configured in the measurement device using the above-described respective distortion gauges <NUM>-<NUM> to <NUM>-<NUM>, a configuration including two Wheatstone bridge circuits of a Wheatstone bridge circuit <NUM>-<NUM> illustrated in <FIG> and a Wheatstone bridge circuit <NUM>-<NUM> illustrated in <FIG> may be adopted.

As illustrated in <FIG>, in the Wheatstone bridge circuit <NUM>-<NUM>, the resistor R1 is provided in the first path <NUM>, and the resistor R2 is provided in the second path <NUM>. The respective measurement units 56A of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> are connected in series, and are provided in the third path <NUM>. A resistor R3 is provided in the fourth path <NUM>.

The resistors R1 to R3 are equal to resistance values of the seven measurement units 56A connected in series when no distortion occurs (also equal to resistance values of the seven measurement unit 56B connected in series).

In the Wheatstone bridge circuit <NUM>-<NUM>, as illustrated in <FIG>, a resistor R5 is provided in the first path <NUM>, a resistor R6 is provided in the second path <NUM>, and a resistor R4 is provided in the third path <NUM>. The respective measurement units 56B of the distortion gauges <NUM>-<NUM> to <NUM>-<NUM> are connected in series, and are provided in the fourth path <NUM>.

The resistors R4 to R6 are equal to resistance values of the seven measurement unit 56B connected in series when no distortion occurs.

In any case of the Wheatstone bridge circuits <NUM>-<NUM> and <NUM>-<NUM>, one end portion of the first path <NUM> and the second path <NUM> is connected to the positive electrode side of the voltage supply source and the positive electrode side of the transmitter, and one end portion of the third path <NUM> and the fourth path <NUM> is connected to the negative electrode side of the voltage supply source and the negative electrode side of the transmitter. In addition, the other end portion of the first path <NUM> and the third path <NUM> is the positive electrode side output of the detection signal, and the other end portion of the second path <NUM> and the fourth path <NUM> is the negative electrode side output of the detection signal.

A voltage is supplied to all of the respective Wheatstone bridge circuits <NUM>-<NUM> and <NUM>-<NUM> from the same voltage supply source, and each of the Wheatstone bridge circuits <NUM>-<NUM> and <NUM>-<NUM> can obtain a different (independent) detection signal.

According to this configuration, two comparable detection signals can be individually acquired from the respective Wheatstone bridge circuits <NUM>-<NUM> and <NUM>-<NUM> to carry out safety level diagnosis.

Details in the above-described respective embodiments can be appropriately changed within the scope not departing from the concept of the invention.

In addition, in the above-described respective embodiments, a configuration in which the easily deformable portion and the distortion gauge are provided in the first internal tooth member has been described as an example. However, the easily deformable portion and the distortion gauge may be provided in the second internal tooth member. Even in this case, the configuration has to be adopted as follows. The second internal tooth member includes the internal tooth ring portion having the internal tooth formed on the inner periphery and the external connection portion connected to the external member, and the easily deformable portion and the distortion gauge are provided therebetween.

In addition, regardless of whether the easily deformable portion and the distortion gauge are provided in either the first internal tooth member or the second internal tooth member, any one of the first internal tooth member and the second internal tooth member may be located on a non-rotating side or on an upstream side in a power transmission direction. In addition, in Embodiments <NUM> to <NUM> described above (excluding Embodiment <NUM>), the distortion gauges <NUM> and <NUM> are attached to all of the pillar members <NUM>. However without being limited thereto, the distortion gauges. <NUM> and <NUM> may be attached to only some of the pillar members <NUM>. In addition, in the above-described embodiments, the distortion gauge <NUM> is disposed on an axial end surface of the pillar member <NUM>. However, without being limited thereto, for example, the distortion gauge <NUM> may be disposed on a surface of the pillar member <NUM> in the circumferential direction.

In addition, in the above-described embodiments, a tubular meshing type gear device has been described as an example of the bending meshing type gear device <NUM>. However, the present invention can also be preferably applied to a bending meshing type gear device other than the tubular type, for example, a bending meshing type gear device adopting a cup type or a silk hat type.

Claim 1:
A bending meshing type gear device (<NUM>) comprising:
a wave generator (30A);
an external gear (<NUM>, <NUM>, <NUM>) flexibly deformed by the wave generator (30A); and
an internal gear (<NUM>, 41A, 41B, 41C, 41D, 41E, 41F) meshing with the external gear (<NUM>, <NUM>),
the internal gear (<NUM>, 41A, 41B, 41C, 41D, 41E, 41F) includes
an internal tooth ring portion (<NUM>) having an internal tooth (<NUM>) formed on an inner periphery,
an external connection portion (<NUM>) provided on a radially outer side of the internal tooth ring portion (<NUM>),
a deformable portion (<NUM>, 414A, 414C, 414D, 414E, 414F) provided between the internal tooth ring portion (<NUM>) and the external connection portion (<NUM>), and
distortion measurement means (<NUM>) provided in the deformable portion (<NUM>, 414A, 414C, 414D, 414E, 414F),
characterized in that
the deformable portion (<NUM>, 414A, 414C, 414D, 414E, 414F) being more deformable than the internal tooth ring portion (<NUM>) when a torque acts on the internal gear (<NUM>, 41A, 41B, 41C, 41D, 41E, 41F).