Drive mechanism

Abstract

A drive mechanism (1) that turns two bodies (M1, M2) to be driven about an axis (C) is provided with a single drive unit (3), a first reducer (70), and a second reducer (80). The drive unit (3) outputs rotational power to a rotating shaft (2) disposed on the axis (C). The first reducer (70) is disposed coaxially with the rotating shaft (2) and, in a state in which a second output part (72) is fixed so as not to rotate, reduces the rotational power at a first reduction ratio to rotate an outer peripheral surface (73) of a first output part (71) in the direction opposite to the rotation direction of the rotating shaft (2). The second reducer (80) is disposed coaxially with the rotating shaft (2) and, in a state in which a third output part (81) is fixed to the first output part (71), reduces the rotational power at a second reduction ratio to rotate an outer peripheral surface (83) of a fourth output part (82). The first body (M1) to be driven is attached to the outer peripheral surface (73) of the first output part (71), and the second body (M2) to be driven is attached to the outer peripheral surface (83) of the fourth output part (82).

Description

Drive mechanism

[0001] The present invention relates to a drive mechanism for turning two driven bodies.

[0002] Conventionally, drive mechanisms for pivotally moving two driven bodies have been known. For example, Patent Document 1 discloses a conveyance device (drive mechanism) that pivots a first arm and a second arm (two driven bodies) around a coaxially arranged pivot shaft, and that includes two rotary motors that rotate the pivot shafts of the first arm and the second arm, respectively.

[0003] JP 2011-199121 A

[0004] However, in the drive mechanism disclosed in Patent Document 1, multiple motors are provided to rotate the two driven bodies, making it difficult to reduce the size of the drive mechanism itself. Therefore, there is room for improvement in reducing the size of the drive mechanism.

[0005] The present invention was conceived in light of these problems, and one of its objectives is to reduce the size of the drive mechanism. However, in addition to this objective, another objective of the present invention is to achieve effects derived from the configurations shown in the "Mode for Carrying Out the Invention" below, which are not obtainable with conventional technology.

[0006] The disclosed drive mechanism can be realized as the following disclosed embodiments (application examples), which solve at least part of the above-mentioned problems. Each of the embodiments from embodiment 2 onwards is an embodiment that can be selected as an additional option, and each of the embodiments from embodiment 2 onwards is an embodiment that can be omitted. None of the embodiments from embodiment 2 onwards discloses an embodiment or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed drive mechanism rotates two driven bodies arranged around an axis line, the drive mechanism comprising: a single drive unit that outputs rotational power to a rotation shaft arranged on the axis line, a first reducer arranged coaxially with the rotation shaft, and a second reducer arranged coaxially with the rotation shaft. The first reducer has a first output unit through which the rotation shaft is inserted and rotatable around the rotation shaft, and a second output unit rotatable on one side of the rotation shaft in the axial direction relative to the first output unit, and with the second output unit fixed so as not to rotate, the rotational power is reduced at a first reduction ratio and output to the first output unit, thereby rotating the outer circumferential surface of the first output unit in a direction opposite to the rotation direction of the rotation shaft. The second reducer has a third output section, the rotation shaft of which is inserted at the other side of the first output section in the axial direction and which is rotatable around the rotation shaft, and a fourth output section, the rotation power of which is reduced at a second reduction ratio and output to the fourth output section with the third output section fixed to the first output section, thereby rotating an outer circumferential surface of the fourth output section. One of the two driven bodies is attached to the outer circumferential surface of the first output section, and the other of the two driven bodies is attached to the outer circumferential surface of the fourth output section.

[0008] Aspect 2. In the above aspect 1, it is preferable that the first reduction ratio is expressed by the following formula 1, and the second reduction ratio is expressed by the following formula 2. Note that a, b, and c are positive values ​​when the rotation direction is the same as the rotation direction of the rotation shaft, and are negative values ​​when the rotation direction is opposite to the rotation direction.

[0009] Aspect 3. In the above-mentioned Aspect 2, it is preferable that the first reduction ratio is different from the second reduction ratio. Aspect 4. In the above-mentioned Aspect 2, it is preferable that the first reduction ratio is less than the second reduction ratio. Aspect 5. In the above-mentioned Aspect 2, it is preferable that the first reduction ratio is half the second reduction ratio. Aspect 6. In the above-mentioned Aspect 2, it is preferable that the first reduction ratio is greater than the second reduction ratio. Aspect 7. In the above-mentioned Aspect 2, it is preferable that the first reduction ratio is the same as the second reduction ratio.

[0010] According to the disclosed invention, the drive mechanism can be made smaller.

[0011] Fig. 2 is a perspective view schematically showing a drive mechanism according to an embodiment. Fig. 3 is a partially exploded perspective view of a compound reducer provided in the drive mechanism of Fig. 1. Fig. 4 is a perspective view schematically showing a reducer unit used in the compound reducer provided in the drive mechanism of Fig. 1. Fig. 5 is a perspective view schematically showing a welding device to which the drive mechanism according to an embodiment is applied.

[0012] A drive mechanism according to an embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and are not intended to exclude various modifications or applications of techniques not explicitly described in the following embodiments. The configurations of the present embodiment can be modified in various ways without departing from the spirit of the invention. Furthermore, they can be selected or combined as needed.

[0013] [I. One Embodiment] [1. Drive Mechanism] Fig. 1 is a perspective view that schematically shows a drive mechanism 1 according to one embodiment. The drive mechanism 1 of this embodiment is a mechanism that rotates two driven bodies M1 and M2 arranged around an axis C, about the axis C. As shown in Fig. 1, the drive mechanism 1 includes a single drive unit 3 that outputs rotational power to a rotating shaft 2 arranged on the axis C, and a compound reducer 4 that is arranged coaxially with the rotating shaft 2.

[0014] Hereinafter, the direction of the axis C will be referred to as the axial direction. Furthermore, a direction perpendicular to the axial direction and away from the axis C will be referred to as the radially outward direction, and a direction perpendicular to the axial direction and toward the axis C will be referred to as the radially inward direction. When no distinction is made between inside and outside, the direction will simply be referred to as the radial direction. A direction perpendicular to the axial direction and rotating around the axis C will be referred to as the circumferential direction. The rotating shaft 2 extends in the axial direction, is disposed so that its center line and the axis C are aligned, and rotates around the axis C. Therefore, the circumferential direction can also be referred to as the rotation direction of the rotating shaft 2. Furthermore, because the driven bodies M1 and M2 rotate around the axis C, the circumferential direction can also be referred to as the rotation direction of the driven bodies M1 and M2.

[0015] The two driven bodies M1 and M2 are provided radially outward of the rotating shaft 2 and spaced apart from the rotating shaft 2, and are objects driven by the drive mechanism 1. More specifically, the two driven bodies M1 and M2 are attached to the outer peripheral surfaces of the substantially cylindrical compound reducer 4 arranged around the rotating shaft 2 (the outer peripheral surface 73 of a first case 71 and the outer peripheral surface 83 of a second output flange 82, which will be described later).

[0016] Hereinafter, of the two driven bodies M1, M2, the driven body M1 (one of the two driven bodies) attached to the outer peripheral surface 73 of the first case 71 of the compound reducer 4 will be referred to as the first driven body M1. Also, of the two driven bodies M1, M2, the driven body M2 (the other of the two driven bodies) attached to the outer peripheral surface 83 of the second output flange 82 of the compound reducer 4 will be referred to as the second driven body M2.

[0017] In this embodiment, both the first driven body M1 and the second driven body M2 revolve around the rotation axis 2 along an imaginary circle (shown by a two-dot chain line in FIG. 1) centered on the axis C. However, it is sufficient that each of the first driven body M1 and the second driven body M2 revolves at least around the axis C, and they do not necessarily have to revolve along a common imaginary circle as shown in FIG. 1.

[0018] Furthermore, although the driven bodies M1 and M2 are illustrated here as being approximately cylindrical and extending in the axial direction, the shapes and types of the driven bodies M1 and M2 are not particularly limited. For example, the driven bodies M1 and M2 may be rectangular pillars or tubular instead of cylindrical, or may be rod-like arms extending in the radial direction. Furthermore, although the two driven bodies M1 and M2 are arranged at the same axial position here, the two driven bodies M1 and M2 may be arranged at different axial positions. Furthermore, the two driven bodies M1 and M2 do not have to be the same object (machine or device) or have the same shape.

[0019] The drive unit 3 is a drive source that rotates the rotating shaft 2. The drive unit 3 is provided with a motor main body that generates rotational power to be output to the rotating shaft 2 and an encoder for adjusting the amount of rotation (drive degree, rotation angle, rotation speed) of the rotating shaft 2. For example, as shown in FIG. 1 , the drive unit 3 is not disposed radially outward of the compound reducer 4 through which the rotating shaft 2 is inserted, but is disposed coaxially with the rotating shaft 2 on the radially inner side of the compound reducer 4 (a position where the entire drive unit 3 completely overlaps the compound reducer 4 when viewed from the axial direction) and on one side of the axial direction. By disposing the drive unit 3 coaxially with the rotating shaft 2, the drive unit 3 is less likely to interfere with the driven bodies M1 and M2 disposed around the rotating shaft 2, ensuring flexibility in the layout of the drive mechanism 1.

[0020] The compound reducer 4 reduces the rotation of the rotating shaft 2 and outputs it. A specific example of the compound reducer 4 will be described below with reference to Figures 1 to 3. Figure 2 is an exploded perspective view of a portion of the compound reducer 4 in Figure 1, with a connecting member 78 (described later) omitted. Figure 3 is a perspective view schematically showing reducers 70 and 80 provided in the compound reducer 4.

[0021] 1, the drive mechanism 1 is provided with only one drive unit 3 that rotationally drives the rotating shaft 2, whereas the compound reducer 4 is provided with two reducers, a first reducer 70 and a second reducer 80. The rotational power of the rotating shaft 2 is input to each of the reducers 70, 80. The drive mechanism 1 distributes the rotational power output from the drive unit 3 to both the first reducer 70 and the second reducer 80, thereby rotating both of the two driven bodies M1, M2 about the axis C.

[0022] The rotating shaft 2 is provided with a first rotating shaft 7R, which is a portion that is inserted into the first reducer 70, and a second rotating shaft 8R, which is a portion that is inserted into the second reducer 80. The first rotating shaft 7R and the second rotating shaft 8R are connected to each other along the axis C and rotate integrally.

[0023] First, the configuration common to the reducers 70, 80 will be described with reference to Figure 3. The reducers 70, 80 are reducers in which the rotating shafts 7R, 8R, cases 71, 81, and output flanges 72, 82 are arranged coaxially with one another. If the rotating shafts 7R, 8R are considered to be first elements, the cases 71, 81 are considered to be second elements, and the output flanges 72, 82 are considered to be third elements, the reducers 70, 80 can be said to be three-element, two-degree-of-freedom reducers. Here, a three-element, two-degree-of-freedom reducer means a reducer in which the rotational speed of the remaining element is uniquely determined when the rotational speeds of two of the three elements are determined.

[0024] The illustrated reducers 70 and 80 are high-precision control reducers that employ a planocentric speed reduction mechanism. ＴＭ However, each of the reducers 70, 80 may be a three-element, two-degree-of-freedom reducer consisting of at least three coaxially arranged elements, and a well-known planetary gear mechanism, harmonic reducer, or the like may be applied.

[0025] Each reducer 70, 80 is provided with spur gears 7s, 8s that mesh with input gears 7i, 8i provided on the outer periphery of the rotating shafts 7R, 8R, and cases 71, 81 and output flanges 72, 82 that are rotatable in accordance with the rotation of the spur gears 7s, 8s.

[0026] Specifically, the first reducer 70 includes a first spur gear 7s, a first case 71 (first output portion), and a first output flange 72 (second output portion). １ The second reducer 80 is provided with a second spur gear 8s, a second case 81 (third output portion), and a second output flange 82 (fourth output portion). The second reducer 80 has a second reduction ratio i ２ is set.

[0027] The first case 71 and the second case 81 have the rotary shafts 7R, 8R inserted therethrough and are rotatable about the rotary shafts 7R, 8R. The first output flange 72 is rotatable relative to the first case 71. Similarly, the second output flange 82 is rotatable relative to the second case 81.

[0028] The cases 71, 81 and the output flanges 72, 82 are coaxial with the rotating shafts 7R, 8R and are provided in a cylindrical (annular) shape centered on the axis C. That is, the rotating shafts 7R, 8R are inserted through the cases 71, 81 and the output flanges 72, 82.

[0029] Each of the cases 71, 81 and each of the output flanges 72, 82 can output rotational power without being constrained by other elements, and can also be used by being attached to another fixed (immovable) member to prevent rotation, or by being constrained to rotate integrally with another rotating element. Therefore, the cases 71, 81 and the output flanges 72, 82 can output rotational power without being constrained by other elements, and can be used by being attached to another fixed (immovable) member to prevent rotation, or by being constrained to rotate integrally with another rotating element. １ , i ２ In other words, it is an element (output section) that can reduce the speed of the rotational power of the rotating shafts 7R and 8R (i.e., the rotating shaft 2) and output it accordingly.

[0030] One common use of the reducers 70, 80 is to output rotational power to the output flanges 72, 82 in a state where the cases 71, 81 are fixed so as not to rotate. １is defined as the value obtained by dividing the rotation speed of the first output flange 72 by the rotation speed of the first rotary shaft 7R when the first case 71 is fixed so as not to rotate. ２ is defined as the value obtained by dividing the rotation speed of the second output flange 82 by the rotation speed of the second rotary shaft 8R when the second case 81 is fixed so as not to rotate.

[0031] The cases 71, 81 are case-shaped members that house the spur gears 7s, 8s on the axis C side (i.e., radially inward). If the output flanges 72, 82 are fixed so as not to rotate, the cases 71, 81 can accommodate the reduction ratio i of the reducers 70, 80. １ , i ２ The output flanges 72, 82 are arranged to rotate in the opposite direction to the rotation direction of the rotary shaft 2, regardless of the position of the output flanges 72, 82. The output flanges 72, 82 are arranged at different axial positions relative to the cases 71, 81. The output flanges 72, 82 can also be considered as members that protrude in the axial direction like a flange. The output flanges 72, 82 that are not fixed so as to be non-rotatable are arranged to rotate in the direction opposite to the rotation direction of the rotary shaft 2, regardless of the position of the output flanges 72, 82. The output flanges 72, 82 are arranged at different axial positions relative to the cases 71, 81. The output flanges 72, 82 are arranged to rotate in the opposite direction to the rotation direction of the rotary shaft 2, regardless of the position of the output flanges 72, 82 ... １ , i ２ The direction of rotation is determined by

[0032] Next, the configuration of each of the reducers 70, 80 will be described with reference to Figures 1 and 2. In the compound reducer 4, the first output flange 72 and first case 71 of the first reducer 70, and the second case 81 and second output flange 82 of the second reducer 80 are arranged in this order from one axial side to the other. In other words, the first output flange 72 is located on one axial side of the first case 71, the second case 81 is located on the other axial side of the first case 71, and the second output flange 82 is located on the other axial side of the second case 81. As described above, the first driven body M1 is fixed to the outer peripheral surface 73 of the first case 71, and the second driven body M2 is fixed to the outer peripheral surface 83 of the second output flange 82.

[0033] 1 has a connecting member 78 provided between the first case 71 and the second case 81. The connecting member 78 connects the first case 71 and the second case 81 so that the cases 71 and 81 rotate together, and is provided in a cylindrical shape centered on the axis C, just like the cases 71 and 81. However, it is also possible to omit the connecting member 78 and use a compound reducer 4 in which the cases 71 and 81 are directly connected to each other.

[0034] The first reducer 70 converts the rotational power of the rotary shaft 2 into a rotational power at a first reduction ratio i １ The first reducer 70, to which the rotational power is transmitted, is decelerated by a reduction ratio i １ , i ２ Regardless of the rotation direction of the rotary shaft 2, the outer peripheral surface 73 of the first case 71 is rotated in the direction opposite to the rotation direction of the rotary shaft 2. As a result, the first driven body M1 fixed to the outer peripheral surface 73 of the first case 71 is rotated in the direction opposite to the rotation direction of the rotary shaft 2.

[0035] The second reducer 80 converts the rotational power of the rotary shaft 2 into a second reduction ratio i ２ The rotational speed is reduced by the first reduction ratio i １ In the second reducer 80, the rotational power of the first case 71 reduced by the reduction ratio i １ , i ２ This determines the direction in which the outer peripheral surface 83 of the second output flange 82 is rotated. As a result, the second driven body M2 fixed to the outer peripheral surface 83 of the second output flange 82 is rotated in the rotation direction of the outer peripheral surface 83.

[0036] Specifically, the first reduction ratio i of the first reducer 70 １ is expressed by the following equation 1, and the second reduction ratio i ２ is expressed by the following equation 2.

[0037]

[0038] The rotational speeds a, b, and c are positive when rotating in the same direction as the rotational direction of the rotary shaft 2, and negative when rotating in the opposite direction to the rotational direction. The rotational speed a of the rotary shaft 2 is positive only, the rotational speed b of the first case 71 is negative only, and the rotational speed c of the second output flange 82 is determined by the reduction ratio i １ , i ２ It can take a positive or negative value depending on

[0039] In the compound reducer 4, the first reduction ratio i １ and second reduction ratio i ２ The rotation direction and rotation speed of the two driven bodies M1 and M2 are determined depending on the relative magnitude relationship between the first reduction ratio i １ and second reduction ratio i ２ The relative magnitude relationship of can be set in various ways, for example, as listed in Table 1 below.

[0040]

[0041] The first reduction ratio i １ is the second reduction ratio i ２ If the rotational direction of the second output flange 82 is less than 1 / 2 the rotational direction of the first case 71 is opposite to that of the first case 71. As a result, the first driven body M1 fixed to the outer peripheral surface 73 of the first case 71 and the second driven body M2 fixed to the outer peripheral surface 83 of the second output flange 82 are rotated in directions different from each other.

[0042] For example, when viewed from one axial side to the other, the counterclockwise direction among the circumferential directions is defined as the first direction, and the clockwise direction is defined as the second direction. When the driving unit 3 rotates the rotating shaft 2 in the first direction (the direction of arrow U1 in FIG. 2), the first case 71 rotates in a second direction (the direction of arrow V2 in FIG. 2) opposite to the first direction, and the second output flange 82 rotates in the first direction (the direction of arrow W1 in FIG. 2). As a result, the first driven body M1 pivots in the second direction (the direction of arrow S2 in FIG. 1), and the second driven body M2 pivots in the first direction (the direction of arrow T1 in FIG. 1).

[0043] Conversely, when the drive unit 3 rotates the rotary shaft 2 in the second direction (the direction of arrow U2 in FIG. 2), the first case 71 rotates in the first direction (the direction of arrow V1 in FIG. 2) opposite to the second direction, and the second output flange 82 rotates in the second direction (the direction of arrow W2 in FIG. 2). As a result, the first driven body M1 pivots in the first direction (the direction of arrow S1 in FIG. 1), and the second driven body M2 pivots in the second direction (the direction of arrow T2 in FIG. 1).

[0044] On the other hand, the first reduction ratio i １ The second reduction ratio i ２ If the fifth setting is larger than the fifth setting, the second output flange 82 rotates in the same direction as the rotation direction of the first case 71. As a result, the first driven body M1 and the second driven body M2 rotate in the same direction.

[0045] That is, when the drive unit 3 rotates the rotary shaft 2 in a first direction (the direction of arrow U1 in FIG. 2), both the first case 71 and the second output flange 82 rotate in a second direction (the directions of arrows V2 and W2 in FIG. 2) opposite to the first direction, causing both the first driven body M1 and the second driven body M2 to pivot in the second direction (the directions of arrows S2 and T2 in FIG. 1).

[0046] Conversely, when the drive unit 3 rotates the rotary shaft 2 in the second direction (the direction of arrow U2 in FIG. 2), both the first case 71 and the second output flange 82 rotate in the first direction (the directions of arrows V1 and W1 in FIG. 2) opposite to the second direction, causing both the first driven body M1 and the second driven body M2 to pivot in the first direction (the directions of arrows S1 and T1 in FIG. 1).

[0047] That is, the first reduction ratio i is set to the first setting, the second setting, the third setting, and the fifth setting. １ and the second reduction ratio i ２and |b| are different, both the first case 71 and the second output flange 82 rotate. As a result, both the two driven bodies M1 and M2 can be rotated by the rotational power of the single drive unit 3. Note that in the fifth setting, the rotational speed c of the second output flange 82 is slower than the rotational speed b of the first case 71 (|b| > |c|). As a result, the second driven body M2 rotates at a slower speed than the first driven body M1.

[0048] In addition, the first reduction ratio i １ is the second reduction ratio i ２ If the first setting is less than half of the first reduction ratio i, the rotation speed c of the second output flange 82 will be faster than the rotation speed b of the first case 71 (|b|<|c|). As a result, the second driven body M2 rotates at a higher speed than the first driven body M1. １ is the second reduction ratio i ２ In the second setting, which is half of the first reduction ratio i, the rotation speed b of the first case 71 and the rotation speed c of the second output flange 82 become equal (|b|=|c|). As a result, the first driven body M1 and the second driven body M2 revolve at the same speed. １ is the second reduction ratio i ２ The second reduction ratio i is greater than half of ２ If the rotational speed b of the first case 71 is set to a third setting less than |b|, the rotational speed b of the first case 71 will be faster than the rotational speed c of the second output flange 82 (|b|>|c|). As a result, the second driven body M2 rotates at a slower speed than the first driven body M1.

[0049] First reduction ratio i １ and the second reduction ratio i ２ In the fourth setting where c is the same as c, the rotation of the rotating shaft 2 is canceled out by the rotation of the second case 81, which rotates integrally with the first case 71, within the second reducer 80. As a result, the second output flange 82 does not rotate (c=0), and only the first case 71 rotates, causing only the first driven body M1 to orbit.

[0050] [2. Actions and Effects] The drive mechanism 1 of this embodiment is configured as described above, and therefore has the following actions and effects. (1) In the drive mechanism 1 of this embodiment, the rotational power output from the single drive unit 3 is distributed to both the first output portion of the first reducer 70 (first case 71 in this embodiment) and the fourth output portion of the second reducer 80 (second output flange 82 in this embodiment). As a result, the two driven bodies M1 and M2 arranged around the axis C can be rotated about the axis C. Therefore, the drive mechanism 1 can be made more compact than conventional drive mechanisms in which multiple drive units are provided according to the number of driven bodies M1 and M2.

[0051] In the drive mechanism 1 of this embodiment, the first reducer 70 and the second reducer 80 are disposed coaxially with the rotating shaft 2. Furthermore, the two driven bodies M1, M2 are attached to the outer peripheral surface 73 of the first case 71 of the first reducer 70 and the outer peripheral surface 83 of the second output flange 82 of the second reducer 80, respectively. In other words, in the drive mechanism 1 of this embodiment, the reducers 70, 80 for transmitting the rotational power of the rotating shaft 2 to the two driven bodies M1, M2 are disposed coaxially radially inward of the two driven bodies M1, M2, and therefore the drive mechanism 1 itself can be made sufficiently compact.

[0052] (2) The reduction ratio i of the reducers 70 and 80 is expressed by the above formulas 1 and 2. １ , i ２ By setting the first reduction ratio i as shown in the first setting, second setting, third setting and fifth setting in Table 1 above, the two driven bodies M1 and M2 can be turned in various ways. １ and the second reduction ratio i ２ If these values ​​are different, both of the two driven bodies M1 and M2 can be turned.

[0053] (4) The first reduction ratio i as shown in the first setting, second setting, and third setting in Table 1 above. １ is the second reduction ratio i ２If the first reduction ratio i is less than the second setting shown in Table 1, the two driven bodies M1 and M2 can be rotated in opposite directions (the directions of the hatched arrows or the dotted arrows shown in FIG. 1). １ is the second reduction ratio i ２ If the rotational speed is half of the rotational speed, the two driven bodies M1 and M2 can be rotated in opposite directions at the same speed.

[0054] (6) The first reduction ratio i as shown in the fifth setting in Table 1 above １ The second reduction ratio i ２ If the first reduction ratio i is a value larger than the fourth setting shown in Table 1, both of the two driven bodies M1 and M2 can be rotated in the same direction (the direction of the arrows S1 and T1 or the direction of the arrows S2 and T2 shown in FIG. 1) and the two driven bodies M1 and M2 can be rotated at different speeds. １ and the second reduction ratio i ２ If these are the same, it is possible to rotate only the first driven body M1 while keeping the position of the second driven body M2 fixed.

[0055] 4 is a perspective view schematically illustrating a welding device 10 to which a drive mechanism 1 according to one embodiment is applied. The welding device 10 resistance-welds metal materials, such as steel and aluminum, using a pair of welding guns 21, 22. Each welding gun 21, 22 corresponds to each of the driven bodies M1, M2 described above. In other words, the two welding guns 21, 22 are driven by the drive mechanism 1. The welding device 10 is attached, for example, to the tip of a robot arm of a vertical articulated robot (not shown). The welding device 10 includes the drive mechanism 1, two welding guns 21, 22, a control unit 11, and a device main body 12.

[0056] Examples of the workpiece W (welding target, indicated by a two-dot chain line in FIG. 4 ) to be welded by the welding device 10 include metal members used in vehicles such as electric vehicles (EVs), hybrid vehicles (HEVs), and plug-in hybrid vehicles (PHEVs). A plug-in hybrid vehicle is a hybrid vehicle that can externally charge or receive power from a battery. A plug-in hybrid vehicle is provided with a charging port (inlet) for inserting a charging cable that supplies power from an external charging facility and a power outlet for external power supply.

[0057] The welding device 10 changes the relative positions of the two welding guns 21, 22 by using the drive mechanism 1 to pivot the two welding guns 21, 22, which serve as the two driven bodies M1, M2, about the axis C.

[0058] Hereinafter, a Cartesian coordinate system having three mutually orthogonal coordinate axes, the X-axis, the Y-axis, and the Z-axis, will be used as a reference for directions in the description of the welding apparatus 10. In this Cartesian coordinate system, the direction along the X-axis will be referred to as the "X direction," the direction along the Y-axis will be referred to as the "Y direction," and the direction along the Z-axis will be referred to as the "Z direction." The X direction includes two directions: the direction from negative to positive on the X-axis and the direction from positive to negative on the X-axis, which are opposite to each other. Therefore, one of the X directions will be referred to as the "X1 direction," and the other as the "X2 direction." Similarly, one of the Y directions will be referred to as the "Y1 direction," and the other as the "Y2 direction." Regarding the Z directions, one will be referred to as the "Z1 direction," and the other as the "Z2 direction."

[0059] The X direction corresponds to the "axial direction" in the description of the drive mechanism 1 above. The X2 direction corresponds to the direction of "one axial side" in the description of the drive mechanism 1 above, and the X1 direction corresponds to the direction of "the other axial side" in the description of the drive mechanism 1 above. The welding device 10 is formed symmetrically in the Y direction. The two welding guns 21, 22 are arranged symmetrically in the Y direction with respect to the axis C. Hereinafter, the welding gun 21 arranged on the Y1 side of the axis C will be referred to as the first welding gun 21, and the welding gun 22 arranged on the Y2 side of the axis C will be referred to as the second welding gun 22. However, the welding device 10 does not have to be completely Y-symmetrical and may be asymmetric in the Y direction.

[0060] Each of the welding guns 21, 22 has an electrode 21E, 22E provided at its end (tip) in the X1 direction, an actuator 21A, 22A provided at its end (base) in the X2 direction, and a main body 21B, 22B provided between the electrode 21E, 22E and the actuator 21A, 22A in the X direction, and has a welding center C21, C22 extending in the X direction. The electrodes 21E, 22E of the welding guns 21, 22 are arranged to overlap with the respective welding centers C21, C22 when viewed in the X direction (when viewed in the axial direction of the rotation shaft 2). Preferably, the centers of the electrodes 21E, 22E of the welding guns 21, 22 and the respective welding centers C21, C22 are arranged on the same line.

[0061] Various known welding guns can be used for the welding guns 21, 22. For example, any of an X-type welding gun, a C-type welding gun, and an indirect welding gun can be used for the first welding gun 21. Furthermore, any of an X-type welding gun, a C-type welding gun, and an indirect welding gun can be used for the second welding gun 22. The electrodes 21E, 22E extend in the X direction and are provided so as to be able to abut against a surface Wf of the workpiece W facing the X2 direction (hereinafter referred to as the "front surface").

[0062] The actuators 21A and 22A are drive sources that bias the electrodes 21E and 22E in the X1 direction. That is, the actuators 21A and 22A bias the electrodes 21E and 22E toward the surface Wf of the workpiece W. The actuators 21A and 22A are provided with a motor body that generates a biasing force that presses the electrodes 21E and 22E toward the surface Wf of the workpiece W, and an encoder for adjusting the rotation amount (drive degree, rotation angle, and rotation speed) of the motor body. The main bodies 21B and 22B incorporate a mechanism (not shown) that transmits the biasing force generated by the motor body of the actuators 21A and 22A to the electrodes 21E and 22E. The main bodies 21B and 22B illustrated in FIG. 4 are cylindrical with a cylindrical axis along the X direction.

[0063] Hereinafter, the element names of the electrode 21E and actuator 21A provided on the first welding gun 21 will be prefixed with "first." The element names of the elements provided on the second welding gun 22 will be prefixed with "second." For example, the electrode 21E provided on the first welding gun 21 will be referred to as the "first electrode 21E," and the actuator 22A provided on the second welding gun 22 will be referred to as the "second actuator 22A."

[0064] The control unit 11 is a controller (electronic control device, control board, controller, etc.) that controls the drive unit 3 of the drive mechanism 1 and the actuators 21A, 22A of the welding guns 21, 22. The device body 12 is a component fixed to the tip of the robot arm. The drive mechanism 1 is attached to this device body 12, and various devices and components may also be attached, including a transformer that converts and outputs voltage to the drive unit 3 of the drive mechanism 1 and the actuators 21A, 22A of the welding guns 21, 22. The device body 12 and the devices and components attached to the device body 12 are fixed (immovable), and therefore are set at fixed locations that non-rotatably restrain the first output flange 72. For example, the device body 12 is disposed on the Z2 side of the drive mechanism 1, and the first output flange 72 is fixed to a transformer attached to the device body 12.

[0065] In this application example, the drive mechanism 1 employs the second setting described above, in which the first case 71 and the second output flange 82 are rotated in opposite directions and at the same speed. The first welding gun 21 is attached to the first case 71 of the first reducer 70. Specifically, the first body portion 21B of the first welding gun 21 is fixed to the outer peripheral surface 73 of the first case 71. As a result, the first electrode 21E is fixed to the first case 71 via the first body portion 21B, and the position of the first electrode 21E is adjusted to a position corresponding to the rotational phase of the first case 71.

[0066] A second welding gun 22 is attached to a second output flange 82 of the second reducer 80. Specifically, a second body portion 22B of the second welding gun 22 is fixed to an outer peripheral surface 83 of the second output flange 82. As a result, the second electrode 22E is fixed to the second output flange 82 via the second body portion 22B, and the position of the second electrode 22E is adjusted to a position corresponding to the rotational phase of the second output flange 82.

[0067] When moving the welding guns 21, 22 away from each other, the drive unit 3 rotationally drives the rotary shaft 2 in the first direction, rotates the outer peripheral surface 73 of the first case 71 in the second direction, and rotates the outer peripheral surface 83 of the second output flange 82 in the first direction. When moving the welding guns 21, 22 closer to each other, the drive unit 3 rotationally drives the rotary shaft 2 in the second direction, rotates the outer peripheral surface 73 of the first case 71 in the first direction, and rotates the outer peripheral surface 83 of the second output flange 82 in the second direction.

[0068] In the welding device 10, the first body portion 21B fixed to the outer peripheral surface 73 of the first case 71 and the second body portion 22B fixed to the outer peripheral surface 83 of the second output flange 82 are rotated in different directions at a constant speed by the drive mechanism 1, thereby changing the relative positions of the welding guns 21, 22. This increases the degree of freedom in dealing with the welding location. In the application example described here, the drive mechanism 1 employs the second setting described above, but a setting other than the second setting (first reduction ratio i １ and second reduction ratio i ２The drive mechanism 1 in which the relative magnitude relationship between the loads is adopted may be applied to the welding device 10.

[0069] [II. Modifications] The above-described embodiment is merely an example, and is not intended to exclude various modifications and application of techniques not explicitly described in this embodiment. Each configuration of this embodiment can be modified in various ways without departing from the spirit of the invention. Furthermore, the configurations can be selected and combined as needed.

[0070] The drive mechanism 1 of this embodiment may include at least a single drive unit 3 and reducers 70, 80. The axial directions of the drive mechanism 1 in the above-described embodiment are merely an example, and these directions may be reversed. In other words, the first output flange 72 and first case 71 of the first reducer 70 and the second case 81 and second output flange 82 of the second reducer 80 may be coaxially arranged in this order at least in the axial direction. In one embodiment, the reducers 70, 80 are configured to have a reduction ratio i １ , i ２ The drive mechanism 1 of the present embodiment is not limited to the configuration in which the drive shaft 14 is set, and other configurations may also be employed. The device to which the drive mechanism 1 of the present embodiment is applied is not limited to the above-described welding device 10. The drive mechanism 1 may be applied to various devices that rotate two driven bodies M1 and M2 about the axis C.

[0071] The present invention is applicable to manufacturing industries that use drive mechanisms.

[0072] REFERENCE SIGNS LIST 1 Drive mechanism 2 Rotating shaft 3 Drive unit 70 First reducer 71 First case (first output unit) 72 First output flange (second output unit) 73 Outer circumferential surface 80 Second reducer 81 Second case (third output unit) 82 Second output flange (fourth output unit) 83 Outer circumferential surface a Rotational speed of rotating shaft b Rotational speed of first case c Rotational speed of second output flange i １ First reduction ratio i ２ Second reduction ratio C Axis M1 First driven body (driven body) M2 Second driven body (driven body)

Claims

1. A drive mechanism for rotating two driven bodies arranged around an axis line, the drive mechanism comprising: a single drive unit that outputs rotational power to a rotating shaft arranged on the axis line; a first output unit through which the rotating shaft is inserted and which is rotatable around the rotating shaft; and a second output unit that is rotatable on one side of the rotating shaft in the axial direction relative to the first output unit, a first reducer arranged coaxially with the rotating shaft, which, with the second output unit fixed so as not to rotate, reduces the rotational power at a first reduction ratio and outputs it to the first output unit, thereby rotating the outer circumferential surface of the first output unit in the direction opposite to the rotational direction of the rotating shaft; a second reducer arranged coaxially with the rotating shaft, the second reducer having: a third output section, the rotating shaft being inserted through the third output section on the other side of the first output section in the axial direction so as to be rotatable around the rotating shaft; and a fourth output section, the fourth output section being rotatable on the other side of the third output section, the second reducer reducing the rotational power at a second reduction ratio and outputting the reduced power to the fourth output section while the third output section is fixed to the first output section, thereby rotating an outer circumferential surface of the fourth output section; wherein one of the two driven bodies is attached to the outer circumferential surface of the first output section, and the other of the two driven bodies is attached to the outer circumferential surface of the fourth output section.

2. The drive mechanism according to claim 1, wherein the first reduction ratio is expressed by the following formula 1, and the second reduction ratio is expressed by the following formula 2. Note that a, b, and c are positive values ​​when the rotation direction is the same as the rotation direction of the rotation shaft, and are negative values ​​when the rotation direction is opposite to the rotation direction.

3. The drive mechanism according to claim 2, wherein the first reduction ratio is different from the second reduction ratio.

4. The drive mechanism according to claim 2, wherein the first reduction ratio is less than the second reduction ratio.

5. A drive mechanism according to claim 2, characterized in that the first reduction ratio is half the second reduction ratio.

6. The drive mechanism according to claim 2, wherein the first reduction ratio is greater than the second reduction ratio.

7. The drive mechanism according to claim 2, wherein the first reduction ratio is the same as the second reduction ratio.

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