Gearing

Abstract

To provide a gear device capable of adjusting two inter-core distances.SOLUTION: A gear device comprises a first shaft 14, a second shaft 16 capable of transmitting rotation to the first shaft 14 through a first gear pair, and a third shaft 18 capable of transmitting rotation to the second shaft 16 through a second gear pair, and further comprises an adjustment mechanism capable of adjusting a first inter-core distance La1 between the first shaft 14 and second shaft 16 and a second inter-core shaft La2 between the third shaft 18 and second shaft 16 by moving the second shaft 16.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to gear arrangements. [Background technology]

[0002] Patent Document 1 discloses a gear device including a first shaft and a second shaft capable of transmitting rotation between the first shaft and the second shaft via a gear pair. This type of gear device may include an adjustment mechanism capable of adjusting the center distance between the first shaft and the second shaft in order to adjust the backlash required for the gear pair. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 58-76846 Summary of the Invention [Problem to be solved by the invention]

[0004] The gear device may include a third shaft capable of transmitting rotation to the second shaft via a gear pair. In this case, in addition to the first center distance between the first shaft and the second shaft, the second center distance between the second shaft and the third shaft also needs to be adjusted. A gear device designed to accommodate such a situation in which adjustment of the two center distances is required has not yet been proposed.

[0005] One object of the present disclosure is to provide a gear device in which the distance between two centers can be adjusted. [Means for solving the problem]

[0006] The gear device disclosed herein is a gear device comprising a first shaft, a second shaft capable of transmitting rotation between the first shaft via a first gear pair, and a third shaft capable of transmitting rotation between the second shaft via a second gear pair, and is equipped with an adjustment mechanism capable of adjusting a first center-to-center distance between the first shaft and the second shaft and a second center-to-center distance between the third shaft and the second shaft by moving the second shaft. Effect of the Invention

[0007] According to the gear device of the present disclosure, the distance between the two centers can be adjusted. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a side view of the gear device according to the embodiment. [Diagram 2] 1 is a partial cross-sectional side view of a gear device according to an embodiment of the present invention; [Diagram 3] FIG. 4 is another partial cross-sectional side view of the gear device according to the embodiment. [Figure 4] FIG. 4 is a diagram showing a part of the cross section AA of FIG. [Diagram 5] FIG. 4 is an enlarged view showing a schematic view of a part of FIG. [Figure 6] FIG. 6 is a diagram showing a part of the cross section BB of FIG. 5. [Figure 7] FIG. 2 is an exploded perspective view of an adjustment shim according to an embodiment. [Figure 8] 13 is a diagram showing a schematic diagram of an initial shim disposed between a main body housing and an auxiliary housing; FIG. [Figure 9] 13 is a diagram illustrating a state in which an initial shim is removed from between a main housing and an auxiliary housing; FIG. [Figure 10] 13 is a diagram showing a state in which an adjustment shim is disposed between a main body housing and an auxiliary housing; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described. The same components are given the same reference numerals, and duplicated explanations will be omitted. In each drawing, for the sake of convenience, components are omitted, enlarged, or reduced as appropriate. The drawings should be viewed according to the orientation of the reference numerals.

[0010] Please refer to Figures 1 and 2. The gear device 10 includes a number of shafts 12, 14, 16, and 18, a housing 20 that supports the number of shafts 12, 14, 16, and 18, and a number of gear pairs 22, 24, and 26 that can transmit rotation between the number of shafts 12, 14, 16, and 18. Figure 2 shows some of the gears that make up the gear pairs 22 and 24 by their pitch circles.

[0011] The multiple shafts 12, 14, 16, 18 include an input shaft 12, a first shaft 14 and a second shaft 16 as intermediate shafts, and a third shaft 18 as an output shaft. Rotation is input to the input shaft 12 from a drive source (not shown). The drive source is, for example, a motor, an engine, a gear motor, or the like. The intermediate shaft is provided in a power transmission path from the input shaft 12 to the output shaft. The output shaft outputs rotation to a driven device (not shown) that is to be driven. The first shaft 14, the second shaft 16, and the third shaft 18 in this embodiment have the role of supporting gear pairs 22, 24 of the parallel shaft gear mechanism, and are arranged parallel to each other.

[0012] The multiple gear pairs 22, 24, 26 can transmit rotation from a shaft on the front stage side to a shaft on the rear stage side at a variable speed. The multiple gear pairs 22, 24, 26 in this embodiment function as a reduction gear mechanism that reduces the speed of rotation. The multiple gear pairs 22, 24, 26 include a first gear pair 22 that transmits rotation between the first shaft 14 and the second shaft 16, and a second gear pair 24 that transmits rotation between the second shaft 16 and the third shaft 18. The second shaft 16 can transmit rotation between the first shaft 14 via the first gear pair 22. The third shaft 18 can transmit rotation between the second shaft 16 via the second gear pair 24. In addition, the multiple gear pairs 22, 24, 26 include a third gear pair 26 that transmits rotation between the input shaft 12 and the first shaft 14. The third gear pair 26 is composed of a pair of bevel gears provided on each of the input shaft 12 and the first shaft 14.

[0013] The first gear pair 22 includes a first driving gear 28 that is rotatable together with the first shaft 14, and a first driven gear 30 that is rotatable together with the second shaft 16. The second gear pair 24 includes a second driving gear 32 that is rotatable together with the second shaft 16, and a second driven gear 34 that is rotatable together with the third shaft 18. The driving gears 28, 32 and the driven gears 30, 34 are spur gears and constitute a parallel shaft gear mechanism. The gears 28, 30, 32, 34 are, for example, involute gears. The gears 28, 30 of the first gear pair 22 can adjust the backlash by adjusting the first center distance La1, which will be described later. Similarly, the gears 30, 32 of the second gear pair 24 can adjust the backlash by adjusting the second center distance La2, which will be described later.

[0014] Please refer to Figures 2 to 4. The housing 20 has a hollow structure that accommodates the multiple shafts 12, 14, 16, 18 and the multiple gear pairs 22, 24, 26 inside. The housing 20 has shaft holes 36, 38, 40 that support the first shaft 14, the second shaft 16, and the third shaft 18. The shaft holes 36, 38, 40 include the first shaft hole 36 that supports the first shaft 14, the second shaft hole 38 that supports the second shaft 16, and the third shaft hole 40 that supports the third shaft 18.

[0015] Bearings 42, 44, 46 that support the shafts 14, 16, 18 are disposed between the shafts 14, 16, 18 and the shaft holes 36, 38, 40. The bearings 42, 44, 46 include a first bearing 42 disposed between the first shaft 14 and the first shaft hole 36, a second bearing 44 disposed between the second shaft 16 and the second shaft hole 38, and a third bearing 46 disposed between the third shaft 18 and the third shaft hole 40.

[0016] The housing 20 includes a pair of wall portions 48 provided on both sides in the axial direction X along the axis of the second shaft 16. The shaft holes 36, 38, 40 corresponding to the first shaft 14, the second shaft 16, and the third shaft 18, respectively, are formed in the pair of wall portions 48 individually.

[0017] Please refer to Figures 4 and 5. The gear device 10 is equipped with an adjustment mechanism 50 that can adjust a first center distance La1 between the first shaft 14 and the second shaft 16 and a second center distance La2 between the third shaft 18 and the second shaft 16 by moving the second shaft 16. The first center distance La1 refers to the distance between the axis C1 of the first shaft 14 and the axis C2 of the second shaft 16. The second center distance La2 refers to the distance between the axis C2 of the second shaft 16 and the axis C3 of the third shaft 18.

[0018] The adjustment mechanism 50 includes a main housing 52 and an auxiliary housing 54 which constitute the housing 20, and adjustment shims 56A, 56B disposed between the main housing 52 and the auxiliary housing 54.

[0019] The main body housing 52 and the auxiliary housing 54 are formed by dividing the housing 20. The main body housing 52 has the above-mentioned first shaft hole 36, and supports the first shaft 14 via the first bearing 42 through the first shaft hole 36. The main body housing 52 supports both ends of the first shaft 14. The main body housing 52 has the above-mentioned third shaft hole 40, and supports the third shaft 18 via the third bearing 46 through the third shaft hole 40. The main body housing 52 supports both ends of the third shaft 18.

[0020] The auxiliary housings 54 are provided in pairs, one on each side of the second shaft 16 in the axial direction X. The pair of auxiliary housings 54 are supported by a common main housing 52. The auxiliary housing 54 has the above-mentioned second shaft hole 38, and supports the second shaft 16 via the second bearing 44 through the second shaft hole 38. Each of the pair of auxiliary housings 54 individually supports each of both ends of the second shaft 16. An outer ring 44a (see FIG. 3) of the second bearing 44 is directly attached to the second shaft hole 38 of the auxiliary housing 54 by fitting (for example, clearance fit).

[0021] The main housing 52 has an accommodation hole 58 that accommodates the auxiliary housing 54. The auxiliary housing 54 has a block shape as a whole, and is fitted into the accommodation hole 58 of the main housing 52. The accommodation hole 58 opens outward in the axial direction X of the second shaft 16, and is covered and blocked by a cover material 60. The cover material 60 is detachably attached to the main housing 52 by bolts or the like.

[0022] The main body housing 52 includes a first receiving surface 62 that receives the auxiliary housing 54 from the first shaft 14 side, and a second receiving surface 64 that receives the auxiliary housing 54 from the third shaft 18 side. The "first shaft 14 side" here refers to the first shaft 14 side in the direction along the imaginary line Lb described below. Similarly, the "third shaft 18 side" refers to the third shaft 18 side in the direction along the imaginary line Lb. The first receiving surface 62 is provided between the first shaft 14 and the second shaft 16. The second receiving surface 64 is provided between the second shaft 16 and the third shaft 18. The receiving surfaces 62, 64 of the main body housing 52 are provided in the receiving hole 58 of the main body housing 52.

[0023] The auxiliary housing 54 has a first received surface 66 received by the first receiving surface 62 and a second received surface 68 received by the second receiving surface 64. The first received surface 66 is provided on a side of the auxiliary housing 54 on the first axis 14 side. The second received surface 68 is provided on a side of the auxiliary housing 54 on the second axis 16 side.

[0024] When viewed from the axial direction X of the second shaft 16, a virtual line Lb is assumed to connect the axis C1 of the first shaft 14 and the axis C2 of the third shaft 18. At this time, the first receiving surface 62 is inclined with respect to the virtual line Lb so as to move away from the virtual line Lb toward the first shaft 14 side. In this embodiment, the first received surface 66 also satisfies the same condition. The second receiving surface 64 is inclined with respect to the virtual line Lb so as to move away from the virtual line Lb on the virtual line Lb toward the third shaft 18 side. In this embodiment, the second received surface 68 also satisfies the same condition. To satisfy this condition, the receiving surfaces 62, 64 in this embodiment are planar.

[0025] The adjustment mechanism 50 can move the second shaft 16 in a main adjustment direction Da that simultaneously increases or decreases the first center distance La1 and the second center distance La2. This main adjustment direction Da is a direction that intersects with the imaginary line Lb when viewed from the axial direction X of the second shaft 16. In this embodiment, this main adjustment direction Da is a direction perpendicular to the imaginary line Lb. The adjustment mechanism 50 can move the second shaft 16 in the main adjustment direction Da by moving the auxiliary housing 54 in the main adjustment direction Da. Hereinafter, the direction that decreases the center distances La1 and La2 in the main adjustment direction Da is referred to as a decrease direction Da1, and the direction that increases the center distances La1 and La2 is referred to as an increase direction Da2.

[0026] The adjustment mechanism 50 is capable of moving the auxiliary housing 54 in a secondary adjustment direction Db along the imaginary line Lb. This allows the auxiliary housing 54 to move along either the first receiving surface 62 or the second receiving surface 64, which are inclined with respect to the imaginary line Lb. In turn, by moving the auxiliary housing 54 along the first receiving surface 62, the second center-to-center distance La2 can be adjusted. In addition, by moving the auxiliary housing 54 along the second receiving surface 64, the first center-to-center distance La1 can be adjusted.

[0027] The adjusting shims 56A, 56B include a first adjusting shim 56A that fills a first gap 70A formed between the second shaft 16 and the first shaft 14, and a second adjusting shim 56B that fills a second gap 70B formed between the second shaft 16 and the third shaft 18. The first gap 70A is formed between the first receiving surface 62 of the main housing 52 and the first received surface 66 of the auxiliary housing 54. The second gap 70B is formed between the second receiving surface 64 of the main housing 52 and the second received surface 68 of the auxiliary housing 54.

[0028] The adjustment shims 56A and 56B are generally plate-shaped. The first adjustment shim 56A supports the auxiliary housing 54 from the first shaft 14 side. The first adjustment shim 56A can adjust the first center distance La1 as well as the positions of the second shaft 16 and the auxiliary housing 54 in the radial direction of the first shaft 14 by changing its thickness. The second adjustment shim 56B supports the auxiliary housing 54 from the third shaft 18 side. The second adjustment shim 56B can adjust the second center distance La2 as well as the positions of the second shaft 16 and the auxiliary housing 54 in the radial direction of the third shaft 18 by changing its thickness. It can also be said that the adjustment mechanism 50 can individually adjust the first center distance La1 and the second center distance La2 by changing the thickness of each of the adjustment shims 56A and 56B.

[0029] Please refer to Figs. 6 and 7. The first adjusting shim 56A and the second adjusting shim 56B have the same configuration, so the first adjusting shim 56A will be referred to in the drawings and the configuration common to both will be described. The adjusting shims 56A and 56B include a pair of thick plates 72 and a plurality of thin plates 74A and 74B sandwiched between the pair of thick plates 72. The thick plates 72 and the thin plates 74A and 74B are made of, for example, metal or the like. The thick plate 72 is used to maintain the overall shape of the adjusting shims 56A and 56B when moving the adjusting shims 56A and 56B. The thickness of the thick plate 72 is, for example, 0.5 mm or more.

[0030] The thin plates 74A, 74B are used to adjust the overall thickness of the adjustment shims 56A, 56B. The thickness of the thin plates 74A, 74B is thinner than the thickness of the thick plate 72, for example, 0.2 mm or less. The multiple thin plates 74A, 74B of this embodiment include multiple first thin plates 74A and multiple second thin plates 74B that are thinner than the first thin plates 74A. The first thin plate 74A is used to adjust the value of the first decimal place in mm, for example, and has a thickness of 0.1 mm. The second thin plate 74B is used to adjust the value of the second decimal place in mm, for example, and has a thickness of 0.01 mm.

[0031] By sandwiching such thin plates 74A, 74B between the thick plates 72, the adjusting shims 56A, 56B as a whole can be handled more easily than in the case where only the thin plates 74A, 74B are handled.

[0032] When the cover material 60 is removed, the adjustment shims 56A, 56B can be inserted into and removed from the accommodation hole 58 in the axial direction X of the second shaft 16. The pair of thick plates 72 have protruding portions 72a that protrude outward in the axial direction X of the second shaft 16 relative to the auxiliary housing 54 and the thin plates 74A, 74B. Through holes 72b are formed in the protruding portions 72a of the pair of thick plates 72. When the adjustment shims 56A, 56B are inserted into and removed from the accommodation hole 58, a wire or other wire is passed through and hooked onto the through hole 72b. By moving the wire in this state, the entire adjustment shims 56A, 56B can be easily inserted into and removed from the accommodation hole 58.

[0033] Please refer to FIG. 5. In addition, the gear device 10 includes a fastener 76 for fastening the auxiliary housing 54 to the main housing 52. The fastener 76 is disposed in the decreasing direction Da1 relative to the auxiliary housing 54. The fastener 76 in this embodiment is a bolt. The fastener 76 is inserted into an insertion hole 78 penetrating the main housing 52 and screwed into a first female screw hole 80 provided in the auxiliary housing 54. The auxiliary housing 54 includes a protruding portion 82 that is protruding in the decreasing direction Da1. The protruding portion 82 is provided between the first receiving surface 66 and the second receiving surface 68 of the auxiliary housing 54. The protruding portion 82 is disposed in a recessed portion 84 that is recessed in the decreasing direction Da1 and provided in the main housing 52. The first female screw hole 80 is formed in the protruding portion 82 of the auxiliary housing 54.

[0034] The fixing device 76 applies a fixing force Fa in the decreasing direction Da1 to the auxiliary housing 54 by being screwed into the first female threaded hole 80. The fixing device 76 applies this fixing force Fa to the auxiliary housing 54, thereby fixing the auxiliary housing 54 to the main housing 52.

[0035] In addition, the gear device 10 includes a pressing member 86 disposed in the increasing direction Da2 relative to the auxiliary housing 54. The pressing member 86 in this embodiment is a bolt. The pressing member 86 is screwed into a second female threaded hole 88 penetrating the main housing 52. The pressing member 86 is held in a state in which it abuts against the auxiliary housing 54 from the increasing direction Da2 by adjusting the amount of screwing into the second female threaded hole 88. In this way, the pressing member 86 can restrict the movement of the auxiliary housing 54 in the increasing direction Da2.

[0036] Next, a method of adjusting the backlash of the gear pairs 22, 24 using the adjustment mechanism 50 will be described with reference to Figures 8, 9, and 10. For ease of explanation, the sizes of the gaps 70A, 70B are exaggerated in each figure.

[0037] Please refer to Figure 8. The backlash of the gear pair 22, 24 refers to the size of the gap between the tooth surfaces when the driving gears 28, 32 and driven gears 30, 34 that make up the gear pair 22, 24 are meshed. The backlash is, for example, normal backlash, which is the minimum distance between the tooth surfaces. In addition, the backlash may be circumferential backlash, which is the length of the arc on the pitch circle of one of the gears.

[0038] First, before the backlash adjustment work, initial shims 90 are placed in advance in the first gap 70A and the second gap 70B between the main housing 52 and the auxiliary housing 54. This work is performed in advance, for example, before the gear device 10 is shipped from the manufacturing factory. The initial shims 90 are designed to have a thickness (e.g., 2.0 mm) such that the backlash of the first gear pair 22 and the second gear pair 24 becomes a predetermined backlash (e.g., 0.1 mm). This makes it possible to prevent the gears 28, 30, 32, and 34 constituting the gear pairs 22 and 24 from strongly hitting each other so that the backlash becomes zero.

[0039] Next, the backlash adjustment work is started. First, at the work site, the actual backlash BLs1 of the first gear pair 22, the actual backlash BLs2 of the second gear pair 24, the actual thickness Ts1 of the initial shim 90 placed in the first gap 70A, and the actual thickness Ts2 of the initial shim 90 placed in the second gap 70B are measured. The actual backlashes BLs1 and BLs2 are measured using a gauge such as a dial gauge or a gap gauge. At this time, the actual thickness of the initial shim 90 in the thickness direction of the adjustment shims 56A and 56B placed in the gaps 70A and 70B is measured.

[0040] Next, as shown in FIG. 9, the initial shims 90 are removed from the first gap 70A and the second gap 70B so that the auxiliary housing 54 can be moved in the decreasing direction Da1. Thereafter, the auxiliary housing 54 is moved in the decreasing direction Da1, thereby making the backlash of the first gear pair 22 and the second gear pair 24 zero. In this embodiment, the backlash can be made zero in this manner by moving the auxiliary housing 54 together with the gears 30 and 32 in the decreasing direction Da1 by its own weight. After this, the actual dimension Tm1 of the first gap 70A and the actual dimension Tm2 of the second gap 70B when the backlash becomes zero are measured by a measuring probe. At this time, the actual dimensions of the gaps 70A and 70B in the thickness direction of the adjustment shims 56A and 56B disposed in the gaps 70A and 70B are measured.

[0041] Next, the target thickness Tt1 of the first adjustment shim 56A required to obtain the target backlash BLt1 of the first gear pair 22 is calculated using the measured actual backlash BLs1, the actual thickness Ts1 of the initial shim 90, and the actual dimension Tm1 of the first gap 70A.

[0042] This is calculated, for example, in the following manner. It is assumed that the amount of change in the size of the first gap 70A due to the presence or absence of a shim (adjustment shim 56A, initial shim 90) disposed in the first gap 70A is proportional to the amount of change in the backlash of the first gear pair 22. The amount of change in the first gap 70A due to the presence or absence of the initial shim 90 can be expressed as a difference value (=Ts1-Tm1) between the actual thickness Ts1 of the initial shim 90 and the actual dimension Tm1 of the first gap 70A. In addition, the amount of change in the backlash of the first gear pair 22 due to the presence or absence of the initial shim 90 can be expressed as the actual backlash BLs1 itself. In addition, the amount of change in the first gap 70A due to the presence or absence of the adjustment shim 56A can be expressed as a difference value (=Tt1-Tm1) between the thickness Tt1 of the adjustment shim 56A and the actual dimension Tm1 of the first gap 70A. Furthermore, the amount of change in backlash due to the presence or absence of the adjusting shim 56A can be expressed by the backlash BLt1 of the first gear pair 22 when the adjusting shim 56A is arranged. By summarizing these, the following formula (1) is established. Using this formula (1), it is possible to calculate the target thickness Tt1 of the first adjusting shim 56A required to obtain the target backlash BLt1. Ts1-Tm1:BLs1=Tt1-Tm1:BLt1... (1)

[0043] For example, suppose that the actual thickness Ts1 of the initial shim 90 is 2.0 (mm), the actual backlash BLs1 is 0.1 (mm), the actual dimension Tm1 of the first gap 70A is 1.1 (mm), and the target backlash BLt1 is 0.005 (mm). In this case, 2.0-1.1:0.1=St1-1.1:0.005, and St1=1.145 (mm).

[0044] In a similar manner, the measured actual backlash BLs2, the actual thickness Ts2 of the initial shim 90, and the actual dimension Tm2 of the second gap 70B are used to calculate the target thickness Tt2 of the adjusting shims 56A and 56B required to obtain the target backlash BLt2 of the second gear pair 24. The target thickness Tt2 can be calculated using the following formula (2). Ts2-Tm2:BLs2=Tt2-Tm2:BLt2 (1)

[0045] Next, as shown in FIG. 10, the thicknesses of the adjusting shims 56A and 56B are adjusted so that the actual thicknesses Tg1 and Tg2 of the adjusting shims 56A and 56B become the obtained target thicknesses Tt1 and Tt2. At this time, the thicknesses of the adjusting shims 56A and 56B are adjusted by increasing or decreasing the number of thin plates 74A and 74B of the adjusting shims 56A and 56B. After this, the adjusting shims 56A and 56B with the adjusted actual thicknesses Tg1 and Tg2 are placed in the gaps 70A and 70B. As a result, the first center distance La1 is adjusted according to the actual thickness Tg1 of the first adjusting shim 56A, and the actual backlash BLg1 of the first gear pair 22 is adjusted according to the first center distance La1. Also, the second center distance La2 is adjusted according to the actual thickness Tg2 of the second adjusting shim 56B, and the actual backlash BLg2 of the second gear pair 24 is adjusted according to the second center distance La2. At this time, the actual backlashes BLg1, BLg2 after adjustment are remeasured, and if the measured values ​​deviate from the target backlashes BLt1, BLt2, the adjustment of the actual thicknesses Tg1, Tg2 of the adjusting shims 56A, 56B is repeated until the target backlashes BLt1, BLt2 are obtained.

[0046] The effects of the above gear device 10 will now be described.

[0047] The gear device 10 includes an adjustment mechanism 50 capable of adjusting the position of the second shaft 16. Thus, both the first center distance La1 and the second center distance La2 can be adjusted by adjusting the position of the second shaft 16. Furthermore, adjusting these two center distances La1 and La2 does not require separate adjustment mechanisms dedicated to the first shaft 14 and the third shaft 18. Thus, the structure for adjusting the two center distances La1 and La2 can be simplified.

[0048] The adjustment mechanism 50 can move the second shaft 16 in a main adjustment direction Da that simultaneously increases or decreases the first center distance La1 and the second center distance La2. Therefore, as described above, by setting the backlash of the first gear pair 22 and the backlash of the second gear pair 24 to zero and then slightly moving the second shaft 16, each backlash can be easily adjusted to a required magnitude. This makes it possible to suitably use the gear device 10 in applications that require low backlash (for example, robot arms and pipe benders).

[0049] The adjustment mechanism 50 can adjust the position of the second shaft 16 by adjusting the position of the auxiliary housing 54. Therefore, the adjustment of the two center distances La1, La2 can be achieved by a simple structure that moves the auxiliary housing 54 itself. Therefore, the configuration around the second shaft 16 can be simplified compared to a case where a complex mechanism such as a double eccentric bush is used. Furthermore, it is possible to avoid the need to downsize the surrounding structure (for example, the second shaft 16) that would accompany the complexity of the adjustment mechanism 50.

[0050] The receiving surfaces 62, 64 are inclined with respect to the imaginary line Lb. Therefore, it is easier to increase the area of ​​the receiving surfaces 62, 64 that receive the auxiliary housing 54 than if the receiving surfaces 62, 64 were parallel to the imaginary line Lb. As a result, the auxiliary housing 54 can be more easily and stably received by the receiving surfaces 62, 64.

[0051] The receiving surfaces 62, 64 are provided between one of the first shaft 14 and the third shaft 18 and the second shaft 16. Here, the one shaft is described as the first shaft 14. A reference structure having the same vertical and horizontal dimensions as the auxiliary housing 54 of the embodiment, and only the receiving surfaces 62, 64 parallel to the imaginary line Lb is assumed. The horizontal dimension here refers to the dimension in the above-mentioned secondary adjustment direction Db as seen from the axial direction X of the second shaft 16, and the vertical dimension refers to the dimension in a direction perpendicular thereto. It is assumed that the receiving surfaces 62, 64 are inclined as in the embodiment and provided between the first shaft 14 (one shaft) and the second shaft 16. In this case, compared to the reference structure, it is easier to bring the first shaft 14 (one shaft) closer to the other shaft (here, the third shaft 18) of the first shaft 14 and the third shaft 18 while avoiding interference with the auxiliary housing 54. As a result, it is easier to reduce the horizontal dimension of the main housing 52.

[0052] The fixture 76 applies a fixing force Fa in the decreasing direction Da1 to fix the auxiliary housing 54. Therefore, compared to the case where the fixing force Fa is applied in the direction along the imaginary line Lb, it is possible to prevent the auxiliary housing 54 from shifting in the same direction. Furthermore, when fixing the auxiliary housing 54, it is possible to prevent deviation in the center distance caused by deviation of the auxiliary housing 54.

[0053] Another feature of the gear device 10 will be described. Refer to Fig. 5. The angle θ between the first receiving surface 62 and the second receiving surface 64 is preferably in the range of 85° or more. This angle θ refers to the angle, as viewed from the axial direction of the second shaft 16, between a line Lc1 extending from the planar first receiving surface 62 toward the third shaft 18 side and a line Lc2 extending from the planar second receiving surface 64 toward the first shaft 14 side, on the second shaft 16 side.

[0054] If the angle θ is small, such as 30°, the load on the main housing 52 increases due to a wedge effect when the auxiliary housing 54 is moved in the decreasing direction Da1. In contrast, if the angle θ is 90° or more, such deformation of the main housing 52 can be prevented. Although there is no particular upper limit to the angle θ, the angle θ is less than 180° because the receiving surfaces 62, 64 are inclined with respect to the imaginary line Lb. In addition, a more preferable range of the angle θ is 85° or more and 95° or less, taking into consideration the ease of molding the first receiving surface 62 and the second receiving surface 64. The angle θ between the first receiving surface 62 and the second receiving surface 64 may be less than 85°.

[0055] Other variations of each component are described.

[0056] The number of the shafts 12, 14, 16, and 18 of the gear device 10 may be three or more, and the specific number is not particularly limited. For example, the number of the shafts 12, 14, 16, and 18 may be three, or five or more. A specific example of the power transmission path passing through the first shaft 14, the second shaft 16, and the third shaft 18 is not particularly limited as long as it includes the second shaft 16 capable of transmitting rotation between the first shaft 14 via the first gear pair 22, and the third shaft 18 capable of transmitting rotation between the second shaft 16 via the second gear pair 24. The power transmission path of the embodiment is an example that passes through the first shaft 14, the second shaft 16, and the third shaft 18 in order. However, in addition to this, for example, the power transmission path may be a path in which power is distributed from the second shaft 16 to each of the first shaft 14 and the third shaft 18.

[0057] There is no particular limitation on the specific example of the gear mechanism constituting the gear pair 22, 24. For example, the gear pair 22, 24 may constitute an intersecting shaft gear mechanism. This means that the first shaft 14 and the third shaft 18 may be arranged parallel to a plane perpendicular to the axis C2 of the second shaft 16.

[0058] The adjustment mechanism 50 may be capable of moving the second shaft 16 so as to increase one of the first center-to-center distance La1 and the second center-to-center distance La2 and decrease the other. This assumes, for example, a case in which the second shaft 16 is provided on the imaginary line Lb between the first shaft 14 and the third shaft 18.

[0059] Although the adjustment mechanism 50 has been described as including the auxiliary housing 54, the adjustment mechanism 50 may not include the auxiliary housing 54, and the specific example is not particularly limited. The adjustment mechanism 50 may adjust the position of the second shaft 16 using, for example, a double eccentric bushing in which a small diameter eccentric bushing and a large diameter eccentric bushing are combined.

[0060] Only one of the first receiving surface 62 and the second receiving surface 64 may be inclined with respect to the imaginary line Lb. It can also be said that the receiving surfaces 62, 64 that receive the auxiliary housing 54 from one of the first shaft 14 and the third shaft 18 may be inclined with respect to the imaginary line Lb. For example, only the first receiving surface 62 may be inclined with respect to the imaginary line Lb, and the second receiving surface 64 may be parallel to the imaginary line Lb.

[0061] Furthermore, the receiving surfaces 62, 64 inclined with respect to the imaginary line Lb do not have to be provided between one of the first shaft 14 and the third shaft 18 and the second shaft 16. This assumes, for example, a case in which the first receiving surface 62 inclined with respect to the imaginary line Lb is provided on the opposite side of the imaginary line Lb to the second shaft 16.

[0062] The fixing device 76 may fix the auxiliary housing 54 by applying a fixing force in a direction along the imaginary line Lb. Alternatively, in order to apply a fixing force in the decrease direction Da1, the fixing device 76 may be disposed in the increase direction Da2 with respect to the auxiliary housing 54. This assumes, for example, that the fixing device 76 disposed between the auxiliary housing 54 and the main housing 52 is a wedge.

[0063] The adjusting shims 56A and 56B may be formed of a single plate. When the adjusting shims 56A and 56B are formed of a plurality of plates, the thicknesses of the thin plates 74A and 74B are not particularly limited.

[0064] The above-mentioned embodiment and modified forms are examples. The technical ideas abstracted from these should not be interpreted as being limited to the contents of the embodiment and modified forms. The contents of the embodiment and modified forms are subject to many design changes, such as changes, additions, and deletions of components. In the above-mentioned embodiment, the contents subject to such design changes are emphasized by adding the notation "embodiment". However, design changes are also permitted even in contents without such notation. The hatching on the cross section of the drawing does not limit the material of the hatched object. The structures referred to in the embodiment and modified forms naturally include structures that are shifted by an error amount that can be considered to be the same when considering manufacturing errors, etc. [Explanation of symbols]

[0065] 10...gear device, 14...first shaft, 16...second shaft, 18...third shaft, 22...first gear pair, 24...second gear pair, 50...adjustment mechanism, 52...main housing, 54...auxiliary housing, 56A, 56b...adjusting shim, 62, 64...receiving surface, 72...thick plate, 74A, 74B...thin plate, 76...fixing device.

Claims

1. A first axis; a second shaft capable of transmitting rotation between the second shaft and the first shaft via a first gear pair; A gear device including a third shaft capable of transmitting rotation between the third shaft and the second shaft via a second gear pair, an adjustment mechanism capable of adjusting a first center-to-center distance between the first shaft and the second shaft and a second center-to-center distance between the third shaft and the second shaft by moving the second shaft; the adjustment mechanism includes a main body housing that supports the first shaft and the third shaft, and an auxiliary housing that supports the second shaft, and is capable of adjusting the first center-to-center distance and the second center-to-center distance by moving the auxiliary housing, the main body housing includes a receiving surface that receives the auxiliary housing from a side of one of the first shaft and the third shaft, A gear device wherein the receiving surface is inclined with respect to an imaginary line connecting the axis of the first shaft and the axis of the third shaft when viewed in the axial direction of the second shaft.

2. The gear device according to claim 1 , wherein the adjustment mechanism is capable of moving the second shaft in an adjustment direction that simultaneously increases or decreases the first center distance and the second center distance.

3. 3. The gear device according to claim 1, wherein the bearing surface is provided between the one shaft and the second shaft.

4. the receiving surface includes a first receiving surface that receives the auxiliary housing from the first shaft side and a second receiving surface that receives the auxiliary housing from the third shaft side, 4. The gear device according to claim 1, wherein an angle between the first receiving surface and the second receiving surface is equal to or greater than 85 degrees.

5. the adjustment mechanism is capable of moving the second shaft in an adjustment direction to simultaneously increase or decrease the first center-to-center distance and the second center-to-center distance, The gear device according to claim 1 , further comprising a fastener that applies a fixing force in the adjustment direction to fix the auxiliary housing to the main housing.

6. the adjustment mechanism includes an adjustment shim disposed between the main housing and the auxiliary housing; The gear device according to claim 1 , wherein the adjusting shim comprises a pair of thick plates and a plurality of thin plates sandwiched between the pair of thick plates.

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