WELL GEAR WITH ONE LOAD SENSOR

Abstract

The present invention relates to a wave gear with a load measuring element, characterized in that it comprises a wave generator with a cam having a wave surface; a flexible bearing into which the cam of the wave generator is inserted; a flexible gear with an annular projection outside the flexible bearing; a rigid gear with internal teeth outside the flexible gear, which meshes with an external gear of the flexible gear; a first body connected to the rigid gear; and a second body rotatably connected to the first body via a support bearing, wherein the projection is coupled to the second body by means of several second screws, and further comprising a load measuring element coupled to the first body by means of the fastening of the second screws; wherein the load measuring element comprises an annular load sensing sensor, and the second screws are fastened by the load sensing sensor.

Description

Harmonic reducer unit with load measuring unit

[0001] The present invention relates to a harmonic reducer unit having a load measuring unit, and more particularly, to a harmonic reducer unit having a load measuring unit.

[0002] A harmonic reducer is a type of high-precision reducer that utilizes the difference in the number of teeth between a flexspline and a circular spline, which are deformed by waves generated by a wave generator, to achieve speed reduction. This harmonic reducer is compact, lightweight, and capable of achieving a high reduction ratio, with a large transmission torque capacity and low backlash, making it suitable for use in industrial fields such as robots that require precise reduction ratios.

[0003] Typically, a harmonic reducer consists of a wave generator, a flexspline, and a circular spline. The waves generated by the wave generator deform the flexspline, causing it to move in a harmonic manner, causing some teeth of the flexspline to mesh with some teeth of the circular spline. Since there is a slight difference in the dimensions of the flexspline (number of teeth) and the circular spline (number of teeth), a reducer with a large reduction ratio can be implemented due to such a difference in dimensions.

[0004] Fig. 1 is an exploded perspective view of a conventional harmonic reducer, and Fig. 2 is a cross-sectional view of a flexspline.

[0005] The harmonic reducer (1) has a circular spline (2), a flex spline (3) concentrically arranged on the inside of the circular spline (2), and a wave generator (4) with an oval outer surface inserted into the flex spline (3).

[0006] The above circular spline (2) is in the shape of a ring and has an inner gear (21) formed on its inner surface that meshes with the outer gear (35) of the flex spline (3).

[0007] The above flexible flexspline (3) has a cylindrical body (31), a ring-shaped diaphragm (32) connected to one end thereof, a ring-shaped boss (33) integrally formed with the diaphragm (32), and an external gear (35) formed on the outer circumferential surface of the opening of the body (31).

[0008] As illustrated by the dotted line in Fig. 2, the diaphragm (32A) of the flexspline (3) may be provided in a ring shape that extends radially outward. A ring-shaped boss portion (33A) is integrally formed along the outer peripheral edge of the diaphragm (32A).

[0009] The above wave generator (4) has a cam plate (41) having an elliptical wave surface, and a wave bearing (42) is fitted onto the outer surface of the cam plate (41).

[0010] The above wave bearing (42) is composed of an inner race (42a), an outer race (42b), and a plurality of balls (42c) that are rolling elements that are provided between the inner and outer races to enable rotation. The inner and outer races (42a, 42b) are flexible.

[0011] Fig. 3 is a cross-sectional view illustrating a conventional harmonic reducer unit.

[0012] As illustrated in Fig. 3, the harmonic reduction unit comprises a first body (5) in the shape of a ring coupled to a circular spline (2), and a second body (6) in the shape of a ring that is rotatably provided with a support bearing (7) on the first body (5).

[0013] The boss portion (33) of the flex spline (3) is connected to the second body (6) by a second connecting bolt (18). The second connecting bolts (18) are connected in multiple numbers spaced apart along the circumferential direction.

[0014] The above first body (5) is connected to the circular spline (2) by a first connecting bolt (19). The first connecting bolts (19) are connected in multiple numbers spaced apart along the circumferential direction.

[0015] In Fig. 3, reference numeral 17 illustrates a first cover coupled to a circular spline (2) by fastening a first coupling bolt (19), and reference numeral 8 illustrates a second cover coupled to a second body (6) by fastening a second coupling bolt (18). The second coupling bolts (18) are fastened in multiple numbers spaced apart along the circumferential direction.

[0016] And drawing symbols 13, 14, and 15 represent seals, 12 and 16 represent O-rings, and 9 and 11 represent generator bearings that rotatably support the wave generator (4) relative to the first cover (17) and the second cover (8) on both sides.

[0017] When the above harmonic reducer unit is mounted on a robot or the like and used, there was a problem in that the external force acting on the harmonic reducer unit could not be measured. In order to measure the external force acting on the harmonic reducer unit, the current of the motor that rotates the wave generator (4) is measured and converted into load torque, but only the torsion of the available parts that occurs during rotation could be measured, and loads other than the rotational direction, especially bending moments or impacts, could not be measured, and there was a problem in that it could not operate in response to this.

[0018] For example, when a harmonic reduction gear unit is mounted on a robot and the robot lifts an object to transport it, if the object is heavy, it can be lifted at a low speed, and if the object is light, it can be lifted at a relatively high speed. However, since the bending moment acting on the harmonic reduction gear unit due to the load of the object cannot be measured, the operation cannot be controlled in response to the weight of the object.

[0019] The present invention has been proposed to solve the problems of the prior art as described above, and aims to provide a harmonic reduction unit having a load measuring unit capable of measuring a bending moment or impact, which is a load in addition to the rotational direction.

[0020] The present invention comprises a wave generator having a cam plate portion having a wave surface, a flex bearing to which the cam plate portion of the wave generator is fitted, a flex spline provided on the outside of the flex bearing and having an annular boss portion, a circular spline provided on the outside of the flex spline and having an inner gear meshing with an outer gear of the flex spline, a first body coupled to the circular spline, and a second body rotatably provided to the first body by a support bearing;

[0021] The above boss portion is connected to the second body by a plurality of second connecting bolts, and further includes a load measuring portion that is connected together by fastening the second connecting bolts; the load measuring portion includes a ring-shaped load detection sensor, and the second connecting bolt is connected by passing through the load detection sensor. A harmonic reducer unit having a load measuring portion is provided.

[0022] In the above, at least three load detection sensors are provided, and are characterized in that they are provided at the fastening position of the second connecting bolt and are spaced apart along the circumferential direction.

[0023] In the above, the load measuring unit is ring-shaped and includes a measuring unit body in which a plurality of bolt holes are formed along the circumferential direction; and the plurality of load detection sensors are characterized in that they are provided at positions where the bolt holes of the measuring unit body are formed.

[0024] In the above, the measuring unit body is characterized by being provided with an amplifier that amplifies a signal sensed and output from each load detection sensor, a body control unit that converts the amplified signal into a load, and a transmitter that transmits the converted load signal.

[0025] In the above, at least three load detection sensors are provided; and the angle between the centers of the axes of two adjacent load detection sensors and the opposite sides of the remaining load detection sensors is characterized in that it is less than 180°.

[0026] In the above, the measuring unit body is characterized in that at least one axial surface thereof is provided with a sealing portion extending along the circumferential direction and protruding in the axial direction.

[0027] In the above, the sealing portion is characterized in that it is provided on both axial sides of the measuring portion body.

[0028] In the above, the sealing portion is characterized in that it is provided on the inside and outside of the bolt hole.

[0029] In the above, a sealing connection is further included, and the sealing connection is characterized in that it is spaced apart along the circumferential direction and is connected to sealing parts provided on the inside and outside of the bolt hole.

[0030] When a harmonic reducer unit equipped with a load measuring unit according to the present invention is mounted on a robot or the like and used, external forces such as bending moments or impacts acting on the harmonic reducer unit can be measured, and the operation of the robot or the like can be controlled in response thereto.

[0031] Figure 1 is an exploded perspective view showing a conventional harmonic reducer.

[0032] Figure 2 is a cross-sectional view showing a flexspline equipped in a harmonic reducer.

[0033] Figure 3 is a cross-sectional view showing a conventional harmonic reducer unit.

[0034] Figure 4 is a cross-sectional view showing a harmonic reducer unit having a load measuring unit according to the present invention.

[0035] Figures 5 to 7 are plan views illustrating a load measuring unit provided in the harmonic reduction gear unit of the present invention.

[0036] All technical and scientific terms used in the description of the present invention, unless otherwise defined, have the meanings commonly understood by those of ordinary skill in the art to which this disclosure pertains. All terms used in this disclosure have been selected for the purpose of more clearly explaining this disclosure and are not intended to limit the scope of rights under this disclosure.

[0037] Expressions such as “comprising,” “having,” and the like used in the description of the present invention should be understood as open-ended terms that imply the possibility of including other embodiments, unless otherwise stated in the phrase or sentence in which the expression is included.

[0038] The singular forms used in the description of the present invention may include plural meanings unless otherwise stated, and the same applies to the singular forms set forth in the claims.

[0039] The expressions “first,” “second,” etc. used in the description of the present invention are used to distinguish between multiple components, and do not limit the order or importance of the components.

[0040] When it is mentioned in the description of the present invention that a component is "connected" or "coupled" to another component, it should be understood that the component can be directly connected or coupled to the other component, or can be connected or coupled via a new other component.

[0041] Hereinafter, with reference to the attached drawings, a harmonic reducer unit equipped with a load measuring unit according to the present invention will be described in detail. In the description of the harmonic reducer unit equipped with a load measuring unit according to the present invention, redundant descriptions of prior art will be omitted.

[0042] Fig. 4 is a cross-sectional view showing a harmonic reducer unit equipped with a load measuring unit according to the present invention, and Figs. 5 to 7 are plan views showing a load measuring unit equipped in the harmonic reducer unit of the present invention.

[0043] In the following description, the vertical direction (B) of FIG. 4 is the axial direction, and the rotation center of the wave generator (110) is the axial center.

[0044]

[0045] As illustrated in FIG. 4, a harmonic reduction unit (100) equipped with a load measuring unit according to the present invention comprises a wave generator (110), a flex bearing (140), a flex spline (120), a circular spline (130), a first body (150), a second body (160), and a load measuring unit (190).

[0046] The above wave generator (110) is provided as a cylindrical hollow body. The wave generator (110) is provided with a cam plate portion (111) having an elliptical wave surface at the axial center. A flex bearing (140) is fitted onto the outer circumferential surface of the cam plate portion (111).

[0047] The above flex bearing (140) is concentric with the wave generator (110) and is provided on the outside of the wave generator (110). The wave generator (110) is inserted and provided in the flex bearing (140). The cam plate portion (111) of the wave generator (110) is fitted into the flex bearing (140). The flex bearing (140) is composed of an inner ring, an outer ring, and a plurality of balls which are rolling elements that are provided between the inner ring and the outer ring so as to be able to rotate, and the inner ring and the outer ring are flexible.

[0048] The above flex spline (120) is concentric with the flex bearing (140) and is provided on the outside of the flex bearing (140). The above flex spline (120) has flexibility.

[0049] The above flexspline (120) is provided with a cylindrical body portion (121), an annular diaphragm (123) extending radially outwardly on one axial side of the body portion (121), an annular boss portion (125) formed along the edge of the diaphragm (123), and an outer gear (127) formed on the outer surface of the other axial side of the body portion (121). The boss portion (125) is provided to have a thickness thicker than the diaphragm (123).

[0050] The diaphragm (123) of the above flex spline (120) may be provided to extend radially inward, and the boss portion (125) may be provided in a ring shape to extend along the radially inner edge of the diaphragm (123).

[0051] The above circular spline (130) is concentric with the above flex spline (120) and is provided on the outside of the above flex spline (120). The above circular spline (130) is provided in a ring shape. An inner gear (131) that meshes with the outer gear (127) of the above flex spline (120) is formed on the inner surface of the above circular spline (130).

[0052] The first body (150) is provided in a ring shape. The first body (150) is provided between the circular spline (130) and the diaphragm (123) of the flex spline (120). The first body (150) is connected to the circular spline (130) by a plurality of first connecting bolts (119). The first connecting bolts (119) are connected in plurality and spaced apart along the circumferential direction of the circular spline (130).

[0053] The second body (160) is provided in a ring shape. The second body (160) is provided on the outside of the first body (150). The second body (160) is rotatably provided on the first body (150) by a support bearing (170). The boss portion (125) of the flex spline (120) is coupled to the second body (160) by a plurality of second coupling bolts (180). The second coupling bolts (180) are spaced apart along the circumferential direction of the boss portion (125) and are fastened in plurality.

[0054] The harmonic reduction gear unit (100) equipped with a load measuring unit according to the present invention may have the flex spline (120) or the circular spline (130) as the output shaft depending on the installation.

[0055] In FIG. 4, drawing reference numeral 107 illustrates a first cover coupled to a circular spline (130) by fastening a first coupling bolt (119), and drawing reference numeral 109 illustrates a second cover coupled to a second body (160) by fastening a second coupling bolt (180).

[0056] And drawing symbols 103, 104, and 105 represent seals, 106 and 108 represent O-rings, and 101 and 102 represent generator bearings that rotatably support the wave generator (110) with respect to the first cover (107) and the second cover (109) on both sides.

[0057]

[0058] The above load measuring unit (190) is provided in a ring shape. The load measuring unit (190) is located between the boss unit (125) and the second cover (109). A bolt hole (1911) is formed in the load measuring unit (190), so that the load measuring unit (190) is coupled to the second body (160) together with the boss unit (125) and the second cover (109) by fastening the second coupling bolt (180).

[0059] As shown in Fig. 5, the load measuring unit (190) comprises a measuring unit body (191), a sealing unit (197), and a plurality of load detection sensors (195).

[0060] The above measuring body (191) is provided in a ring shape. A plurality of bolt holes (1911) are formed along the circumferential direction in the measuring body (191).

[0061] The above measuring unit body (191) may be provided by being divided into three or more circular arcs, and the circular arcs may be provided spaced apart in the circumferential direction. A plurality of bolt holes (1911) may be formed along the extension direction in the measuring unit body (191) divided into three or more circular arcs.

[0062] An example of the above measuring unit body (191) may be a PCB, and the measuring unit body (191) is equipped with an amplifier that amplifies a signal sensed and output from each load measuring sensor (195), a main body control unit that converts the amplified signal into a load, and a transmitter that transmits the converted load signal.

[0063] The sealing portion (197) is made of rubber. The sealing portion (197) extends along the circumferential direction on at least one axial surface of the measuring body (191) and is formed to protrude in the axial direction. It is preferable that the sealing portion (197) be provided on both axial surfaces of the measuring body (191).

[0064] The above sealing portion (197) is formed in a ring shape extending along the circumferential direction. The sealing portion (197) is provided on the inner and outer sides of the bolt hole (1911). The sealing portion (197) is provided in multiple numbers spaced apart in the radial direction, thereby enhancing the sealing action and buffering effect.

[0065] The sealing portion (197) may be formed in a shape that extends in the circumferential direction and is curved inward and outward in the radial direction, or may be formed in a zigzag shape, as shown in the enlarged view of Fig. 5. When the sealing portion (197) is formed in a curved shape, the area of ​​the sealing portion increases, so that the cushioning effect of the sealing portion (197) becomes greater than that of a straight sealing portion (197), and the sealing portion can be compressed and sealed with a greater load.

[0066] By providing the sealing portion (197), leakage of internal lubricant or intrusion of external foreign substances is prevented by the sealing portion (197), so that there is no need to provide a separate O-ring, and reliable sealing is possible by the sealing portion (197), and since the sealing portion (197) acts as a buffer, the measuring unit body (191) is prevented from being pressed by direct contact with the boss portion (125) and the second cover (109), so that damage or breakage of the measuring unit body (191) is prevented.

[0067] A sealing connection part (198) may be further included between the sealing parts (197) provided radially spaced apart from one axial side and both sides of the measuring body (191).

[0068] The sealing connection portion (198) is provided in multiple numbers, spaced apart along the circumferential direction of the measuring body (191), and connected to the sealing portion (197) provided on the inside and outside of the bolt hole (1911). The sealing connection portion (198) may be provided between each bolt hole (1911). In addition, when the measuring body (191) is provided by being divided into three or more arcs, the sealing connection portion (198) may be provided between the ends of neighboring arcs.

[0069] By providing the above sealing connection part (198), it acts as a support for the sealing part (197), and the intrusion of leaked lubricant or foreign substances by the sealing part (197) and the sealing connection part (198) is prevented, thereby enhancing the sealing effect.

[0070] The above load detection sensor (195) is provided in multiple numbers. The load detection sensor (195) is in a ring shape, and an example of the load detection sensor (195) may be a piezoelectric sensor. The multiple load detection sensors (195) are provided at positions where the bolt holes (1911) of the measuring body (191) are formed. When the measuring body (191) is formed in three or more arc shapes, the load detection sensor (195) is provided in each measuring body (191).

[0071] The above load detection sensor (195) is provided between the second cover (109) and the measuring body (191) or between the boss (125) and the measuring body (191) at the location where the bolt hole (1911) is formed.

[0072] The above load detection sensor (195) is provided in multiple numbers at the fastening position of the second coupling bolt (180) and spaced apart along the circumferential direction. At least three load detection sensors (195) are provided. The load detection sensors (195) are fastened to the second coupling bolt (180) and are pressurized and fixed by the second coupling bolt (180).

[0073] When a load in the direction of arrow "B" of Fig. 4 is applied to the harmonic reducer unit (100) equipped with a load measuring unit while the load detection sensor (195) is pressurized by the second coupling bolt (180), the load is sensed by each load detection sensor (195). The load measured by the load detection sensor (195) is calculated as shown in the equation below.

[0074]

[0075] (F θ is the load applied to each second connecting bolt (180),

[0076] θ is the position of the second connecting bolt (180) along the circumferential direction,

[0077] d PCD is the pitch diameter of the support bearing (170),

[0078] n boltis the number of second coupling bolts (180),

[0079] Fa is the axial external force acting on the circular spline (130) or the second body (160),

[0080] M tilt is the bending moment acting on the second body (160) by the load in the “A” direction.

[0081]

[0082] In the above equation, variables (Fa, M tilt , θ) are three, so at least three load detection sensors (195) are provided and the sensed values ​​are input and can be calculated respectively. It is preferable to provide four load detection sensors (195) for error checking.

[0083] Figure 6 is a drawing showing a load measuring unit (190) equipped with three load detection sensors (195).

[0084] As illustrated in FIG. 6, the angle between the axis centers of the neighboring load sensors (195a, 195c) is less than 180°, the angle between the axis centers of the neighboring load sensors (195a, 195c) is less than 180°, the angle between the axis centers of the neighboring load sensors (195a, 195b) is less than 180°, the angle between the axis centers of the neighboring load sensors (195a, 195c) is less than 180°, and the angle between the axis centers of the neighboring load sensors (195b, 195c) is less than 180°, the angle between the axis centers of the neighboring load sensors (195a) is less than 180°.

[0085] If the angle between the center of the axis of the two adjacent load detection sensors (195) and the opposite side of the remaining load detection sensors (195) is greater than 180°, the range of the measured area becomes narrow, and the load applied to each second connecting bolt (180) may not be accurately calculated.

[0086] Therefore, it is preferable that the angle between the center of the axis of the two adjacent load detection sensors (195) and the opposite side of the remaining load detection sensors (195) be less than 180°.

[0087] For error checking, it is more preferable to have four load detection sensors (195) as shown in Fig. 7.

[0088] In the case where four load detection sensors (195) are provided, the angle between the axis centers of the neighboring load detection sensors (195a, 195d) and the opposite side angle (θbc) of the remaining load detection sensors (195b, 195c) is less than 180°, the angle between the axis centers of the neighboring load detection sensors (195d, 195c) and the opposite side angle (θab) of the remaining load detection sensors (195a, 195b) is less than 180°, the angle between the axis centers of the neighboring load detection sensors (195b, 195c) and the opposite side angle (θad) of the remaining load detection sensors (195a, 195d) is less than 180°, the angle between the axis centers of the neighboring load detection sensors (195a, 195b) and the opposite side angle (θc) of the remaining load detection sensors (195c, The angle (θab) opposite to 195d) is less than 180°.

[0089]

[0090] As described above, since at least three load measuring units (190) are provided in the harmonic reducer unit (100), the load measuring units (190) are pressurized by the second coupling bolt (180), and external forces such as bending moments or impacts acting on the harmonic reducer unit (100) can be measured, and the operation of a robot or the like can be controlled in response to this.

[0091]

[0092] When a harmonic reducer unit equipped with a load measuring unit according to the present invention is mounted and used, it is possible to measure external forces such as bending moments or impacts acting on the harmonic reducer unit, and when mounted on a robot or the like to lift an object, the bending moments, impacts, etc. acting on the harmonic reducer unit according to the load of the object are measured, thereby enabling operation to be controlled in response to the weight of the object.

Claims

1. A wave generator (110) having a cam plate portion (111) having a wave surface, a flex bearing (140) in which the cam plate portion (111) of the wave generator (110) is fitted, a flex spline (120) provided on the outside of the flex bearing (140) and having an annular boss portion (125), a circular spline (130) provided on the outside of the flex spline (120) and having an inner gear (131) that meshes with an outer gear (127) of the flex spline (120), a first body (150) coupled to the circular spline (130), and a second body (160) rotatably provided on the first body (150) by a support bearing (170); The above boss portion (125) is coupled to the second body (160) by a plurality of second coupling bolts (180), and further includes a load measuring portion (190) coupled together by fastening the second coupling bolts (180); the load measuring portion (190) includes a ring-shaped load detection sensor (195), and the second coupling bolt (180) is characterized in that it is fastened by passing through the load detection sensor (195), a harmonic reducer unit having a load measuring portion.

2. A harmonic reducer unit having a load measuring unit, characterized in that in the first paragraph, at least three load detection sensors (195) are provided, and are provided at the fastening position of the second coupling bolt (180) and spaced apart along the circumferential direction.

3. A harmonic reducer unit having a load measuring unit, characterized in that in the second paragraph, the load measuring unit (190) is ring-shaped and includes a measuring unit body (191) in which a plurality of bolt holes (1911) are formed along the circumferential direction; and the plurality of load detection sensors (195) are provided at positions where the bolt holes (1911) of the measuring unit body (191) are formed.

4. A harmonic reducer unit having a load measuring unit, characterized in that in the third paragraph, the measuring unit body (191) is provided with an amplifier that amplifies a signal sensed and output from each load detection sensor (195), a body control unit that converts the amplified signal into a load, and a transmitter that transmits the converted load signal.

5. A harmonic reducer unit having a load measuring unit, characterized in that in any one of the second to fourth clauses, at least three load detection sensors (195) are provided; and the angle between the center of the axis of two adjacent load detection sensors (195) and the opposite side of the remaining load detection sensors (195) is less than 180°.

6. A harmonic reducer unit having a load measuring unit, characterized in that, in the third paragraph, at least one axial surface of the measuring unit body (191) is provided with a sealing portion (197) extending along the circumferential direction and protruding in the axial direction.

7. A harmonic reducer unit having a load measuring unit, characterized in that in the 6th paragraph, the sealing portion (197) is provided on both axial sides of the measuring unit body (191).

8. A harmonic reduction gear unit having a load measuring unit, characterized in that the sealing portion (197) in the 6th or 7th clause is provided on the inside and outside of the bolt hole (1911).

9. A harmonic reducer unit having a load measuring unit, characterized in that in the 8th paragraph, a sealing connection part (198) is further included, and the sealing connection part (198) is spaced apart along the circumferential direction and is connected to a sealing part (197) provided on the inside and outside of a bolt hole (1911).

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