Power transmission device

Abstract

To provide a power transmission device which is advantageous to reduce the axial size.SOLUTION: The power transmission device includes a rotary body 22 having an input shaft 20 to which rotation is input from a driving machine, a crank shaft to which the rotation of the input shaft 20 is transmitted via a rotation transmission mechanism, an external tooth gear to be oscillated by an eccentric body of the crank shaft, and a carrier 34 arranged on the axial input side with respect to the external tooth gear. On the input side surface of the carrier 34, a recessed part 92 is provided at a position overlapping the whole of an opposite input side end 20a of the input shaft 20 in view from the axial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power transmission device.

Background Art

[0002] Patent Document 1 discloses a power transmission device including a rotating body having an input shaft to which rotation is input from a drive machine, a crankshaft to which the rotation of the input shaft is transmitted via a rotation transmission mechanism, an external gear that is swung by an eccentric body of the crankshaft, and a carrier disposed on the input side in the axial direction with respect to the external gear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor of the present application has recognized that there is room for improvement in the power transmission device of Patent Document 1 in order to advantageously reduce the axial dimension of the power transmission device.

[0005] Therefore, one object of the present disclosure is to provide a power transmission device that is advantageous for reducing the axial dimension.

Means for Solving the Problems

[0006] The power transmission device of the present disclosure is a power transmission device including a rotating body having an input shaft to which rotation is input from a drive machine, a crankshaft to which the rotation of the input shaft is transmitted via a rotation transmission mechanism, an external gear that is swung by an eccentric body of the crankshaft, and a carrier disposed on the input side in the axial direction with respect to the external gear, wherein a recess is provided on the input side surface of the carrier at a position overlapping the entire anti-input side end portion of the input shaft when viewed from the axial direction.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0008] Embodiments for carrying out the power transmission device of the present disclosure will be described. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. In each drawing, for convenience of explanation, components are appropriately omitted, enlarged, or reduced. The drawings are to be viewed in accordance with the orientation of the reference numerals.

[0009] (First Embodiment) Referring to FIG. 1. The power transmission device 10 includes a drive machine 12 and a speed reducer 14 to which rotation is input from the drive machine 12.

[0010] The drive machine 12 in this embodiment is a motor. In addition, the drive machine 12 may be, for example, a gear motor, an engine, or the like. The drive machine 12 includes a drive shaft 16 that outputs the rotation generated inside itself, and a drive machine casing 18 that houses the drive shaft 16.

[0011] The speed reducer 14 includes a rotating body 22 having an input shaft 20 to which rotation is input from the drive machine 12, a rotation transmission mechanism 24 that transmits the rotation of the input shaft 20, a crank shaft 26 to which the rotation of the input shaft 20 is transmitted via the rotation transmission mechanism 24, an external gear 30 that is swung by an eccentric body 28 of the crank shaft 26, an internal gear 32 that meshes with the external gear 30, an input side carrier 34 disposed on the axial input side with respect to the external gear 30, and a counter input side carrier 36 disposed on the axial counter input side with respect to the external gear 30. In addition to this, the speed reducer 14 includes a speed reducer casing 38 disposed on the axial outer side with respect to the external gear 30, and an adapter 40 that connects the other components of the speed reducer 14 and the drive machine casing 18.

[0012] In this embodiment, a distribution type eccentric swing type speed reducer will be described as the speed reducer 14. In this type of speed reducer 14, a plurality of crank shafts 26 are arranged at positions radially offset with respect to the swing center C30a of the external gear 30. Hereinafter, the direction along the swing center C30a of the external gear 30 will be simply referred to as the axial direction, and with respect to the radial direction and the circumferential direction of the circle centered on the swing center C30a, they will also be simply referred to as the radial direction and the circumferential direction. Also, in the power transmission device 10, one axial side (the left side of the drawing in FIG. 1) where the drive machine 12 is located is referred to as the input side, and the axial opposite side (the right side of the drawing in FIG. 1) is referred to as the counter input side.

[0013] The speed reducer 14 includes a fixing member 42 fixed to an external fixed member (not shown) and an output member 44 that outputs rotation to an external driven member (not shown). Here, an example will be described in which the carriers 34 and 36 constitute the fixing member 42 and the speed reducer casing 38 constitutes the output member 44. In this embodiment, the input side carrier 34 is indirectly fixed to the fixed member via the adapter 40, and the pin 70 (described later) and the counter input side carrier 36 are also indirectly fixed to the fixed member via the adapter 40 and the input side carrier 34. The driven member is driven by the output of the output member 44. The driven member is, for example, a part of various machines such as industrial machines such as machine tools and construction machines, robots such as industrial robots and service robots, conveyors, and transportation equipment such as vehicles.

[0014] The rotating body 22 includes, in addition to the input shaft 20, a first pinion 46 that is rotatable integrally with the input shaft 20. Details of the rotating body 22 will be described later.

[0015] The rotation transmission mechanism 24 can transmit the rotation of the rotating body 22 to the crankshaft 26. The rotation transmission mechanism 24 of this embodiment can transmit the rotation of the rotating body 22 to the crankshaft 26 after decelerating the rotation. The rotation transmission mechanism 24 constitutes a rotation transmission path R from the rotating body 22 to the crankshaft 26, and transmits rotation through the rotation transmission path R. The rotation transmission mechanism 24 of this embodiment includes a first gear 50 that forms a first gear set 48 in combination with the first pinion 46 of the rotating body 22, a second gear set 52 provided on the output side of the rotation transmission path R with respect to the first gear set 48, and an intermediate shaft 54 provided between the first gear set 48 and the second gear set 52 in the rotation transmission path R.

[0016] The first gear 50 meshes with the first pinion 46. The first gear 50 of this embodiment is provided so as to be rotatable integrally with the intermediate shaft 54. This is realized using a spline in this embodiment, but it may also be realized using a key or the like. The first gear set 48 of this embodiment can transmit the rotation of the rotating body 22 to the intermediate shaft 54 after decelerating the rotation.

[0017] The second gear set 52 includes a second pinion 56 provided so as to be rotatable integrally with the intermediate shaft 54, and a second gear 58 that meshes with the second pinion 56. The second gear 58 of this embodiment is provided so as to be rotatable integrally with the crankshaft 26. This is realized using a spline in this embodiment, but it may also be realized using a key or the like. The second gear set 52 of this embodiment can transmit the rotation of the intermediate shaft 54 to the crankshaft 26 after decelerating the rotation.

[0018] The intermediate shaft 54 axially penetrates each of the carriers 34, 36 and the external gear 30. The first gear 50 is provided at the input side end of the intermediate shaft 54, and the second pinion 56 is provided at the anti-input side end thereof. Intermediate shaft bearings 60 are arranged between the intermediate shaft 54 and each of the carriers 34, 36.

[0019] In this embodiment, a second gear 58 is provided on each of the plurality of crankshafts 26 so as to be integrally rotatable. A common second pinion 56 meshes with the second gears 58 of each of the plurality of crankshafts 26, and the rotation of the second pinion 56 is distributed from the second pinion 56 to each of the plurality of crankshafts 26.

[0020] The crankshaft 26 includes at least one eccentric body 28, and in this embodiment, a total of two eccentric bodies 28 are included. The eccentric body 28 has a circular shape eccentric with respect to the rotation center line C26 of the crankshaft 26. The eccentric body 28 can swing the external gear 30 by rotating around the rotation center line C26 of the crankshaft 26. Here, "swing" means that the gear center C30b of the external gear 30 rotates around the swing center C30a. The number of the eccentric bodies 28 is not particularly limited, and may be either a single one or three or more.

[0021] The external gears 30 are individually provided corresponding to each of the plurality of eccentric bodies 28, and are supported by the corresponding eccentric bodies 28 via eccentric bearings 62.

[0022] The carriers 34, 36 include crankshaft holes 64 through which the crankshafts 26 are inserted. The crankshaft holes 64 of this embodiment are provided at positions offset from the swing center C30a of the external gear 30. The carriers 34, 36 of this embodiment further include a central hole 66 surrounding the swing center C30a of the external gear 30. Crankshaft bearings 68 are arranged between the crankshaft 26 and each of the carriers 34, 36.

[0023] Pins 70 project axially from the carriers 34, 36. A plurality of pins 70 are provided at intervals in the circumferential direction. The pins 70 penetrate the external gear 30 in the axial direction and can receive a load from the external gear 30 when the external gear 30 swings. The pins 70 of this embodiment connect the input-side carrier 34 and the anti-input-side carrier 36.

[0024] Carriers 34 and 36 can be synchronized with the rotation component of the external gear 30 during the operation of the power transmission device 10. Here, "synchronizing with the rotation component of the external gear 30" means that within a numerical range including zero, the rotation components of carriers 34 and 36 are synchronized with the rotation component of the external gear 30. As in this embodiment, when carriers 34 and 36 become the fixed members 42 and the rotation components of carriers 34 and 36 are maintained at zero, the rotation of the external gear 30 is restricted by carriers 34 and 36 and pins 70, so that the rotation component of the external gear 30 is also maintained at zero. As a result, the rotation components of carriers 34 and 36 are synchronized with the rotation component of the external gear 30. On the contrary, when carriers 34 and 36 become the output members 44, the external gear 30 rotates, and its rotation component is transmitted to carriers 34 and 36 via pins 70. Thereby, carriers 34 and 36 rotate with a rotation component of the same magnitude as the rotation component of the external gear 30, and thereby are synchronized with the rotation component of the external gear 30.

[0025] The speed reducer casing 38 of this embodiment is integrally provided by the same member as the internal gear 32. In addition, the speed reducer casing 38 may be provided separately from the internal gear 32. A main bearing 72 is disposed between the speed reducer casing 38 and each of the carriers 34 and 36.

[0026] The adapter 40 of this embodiment connects the input-side carrier 34 of the speed reducer 14 and the drive machine casing 18. The adapter 40 is fixed to the input-side carrier 34 by a plurality of first fixing tools 74 such as bolts. Further, the drive machine casing 18 is fixed to the adapter 40 by a plurality of second fixing tools (not shown) such as bolts. Inside the adapter 40, some components of the speed reducer 14 such as the rotating body 22 and the first gear set 48 are accommodated.

[0027] An example of the operation of the above-described power transmission device 10 will be described. The power transmission device 10 of the present embodiment includes a plurality of gear sets including a third gear set composed of an external gear 30 and an internal gear 32 in addition to the first gear set 48 and the second gear set 52. When rotation is input from the drive machine 12 to the input shaft 20, the rotation of the input shaft 20 is decelerated by the plurality of gear sets, and then rotation is output from the output member 44 to the driven member. In this process, when the external gear 30 swings due to the eccentric body 28 of the crankshaft 26, the meshing position between the external gear 30 and the internal gear 32 changes in the circumferential direction. Accordingly, each time the crankshaft 26 makes one rotation, one of the gears of the external gear 30 and the internal gear 32 (here, the internal gear 32) rotates, and the rotation component thereof is taken out by the output member 44. At this time, the rotation component decelerated compared to the rotation of the crankshaft 26 is taken out by the output member 44.

[0028] Moving on to the description of the rotating body 22. The rotating body 22 includes a first restricting body 80 attached to the input shaft 20 in addition to the input shaft 20 and the first pinion 46.

[0029] The input shaft 20 of the present embodiment is integrally provided by the same member as the drive shaft 16 of the drive machine 12. In addition to this, the input shaft 20 may be provided separately from the drive shaft 16 and configured to be able to transmit the rotation of the drive shaft 16 by means of a coupling or the like. The input shaft 20 of the present embodiment is provided at a position offset in the radial direction with respect to the swing center C30a of the external gear 30.

[0030] The input shaft 20 is rotatably supported via an input bearing 84 incorporated in a casing body 82 that houses the input shaft 20. The casing body 82 of the present embodiment is composed of a drive machine casing 18 and an adapter 40, and the input bearing 84 is incorporated in the drive machine casing 18. The casing body 82 of the present embodiment is connected to the input side carrier 34 so as not to be relatively rotatable by using the above-described first fixture 74 or the like.

[0031] Refer to FIG. 2. The first pinion 46 of this embodiment is provided separately from the input shaft 20. In addition to this, the first pinion 46 may also be integrally provided by the same member as the input shaft 20. The first pinion 46 includes a first pinion hole 46a provided at the central portion of the first pinion 46. The input shaft 20 is inserted into the first pinion hole 46a in a state of being press-fitted. The first pinion 46 is connected to the input shaft 20 so as to be integrally rotatable by a key, spline, or the like. The first pinion 46 of this embodiment is connected to the input shaft 20 so as to be integrally rotatable using a key 47. The key 47 is fitted into a key groove 46d provided in the first pinion hole 46a of the first pinion 46 and a key groove 20c provided in the input shaft 20.

[0032] The first restricting body 80 of this embodiment includes a first bolt 86 attached to the input shaft 20, a first restricting member 88 attached to the input shaft 20 by the first bolt 86, and a first washer 90 disposed between the head of the first bolt 86 and the first restricting member 88. The first bolt 86 is attached to the input shaft 20 by being screwed into a female screw hole that opens on the end face of the input shaft 20. The first restricting member 88 has an annular shape surrounding the shaft portion of the first bolt 86, and is attached to the input shaft 20 when the head of the first bolt 86 hits through the first washer 90 from the anti-input side. The first washer 90 is, for example, a spring washer or the like that can bias the first restricting member 88 toward the input side.

[0033] The first restricting body 80 restricts the axial movement of the first pinion 46 by hitting the first pinion 46 from the anti-input side. Thereby, the first restricting body 80 prevents the first pinion 46 from detaching from the input shaft 20. In order to achieve this, in this embodiment, the first restricting member 88 hits the first pinion 46 from the anti-input side.

[0034] A recess 92 is provided on the input-side surface of the input-side carrier 34. The input-side carrier 34 includes an input-side outer surface 94 that axially faces at least a part of the first gear 50. The recess 92 is recessed on the anti-input side with respect to the input-side outer surface 94 of the input-side carrier 34. The recess 92 of the present embodiment is a through-hole 96 that axially penetrates the input-side carrier 34. The through-hole 96 of the present embodiment is a crankshaft hole 64 through which the crankshaft 26 is inserted.

[0035] Refer to FIGS. 2 and 3. In FIG. 3, a part of the III-III cross-section of the rotating body 22 in FIG. 2 and the input-side carrier 34 are shown. The recess 92 is provided at a position that overlaps the entire anti-input-side end 20a of the input shaft 20 when viewed axially. Here, the statement that the recess 92 is at a position that overlaps the entire A means that, when viewed axially, the internal space of the recess 92 is at a position that overlaps the entire A. In the example described here, when viewed axially, the internal space of the recess 92 is at a position that overlaps the entire anti-input-side end 20a of the input shaft 20. In other words, the statement that the recess 92 is at a position that overlaps the entire A means that, when viewed axially, the entire A is contained inside the outer shape formed by the inner peripheral surface of the recess 92. The anti-input-side end 20a of the input shaft 20 here refers to a part that includes the axial range from the anti-input-side end face 20b of the input shaft 20 to the input-side end face 46b of the first pinion 46. The recess 92 of the present embodiment is provided at a position that also overlaps the entire first pinion 46 in addition to the anti-input-side end 20a of the input shaft 20 when viewed axially.

[0036] The power transmission device 10 is configured to satisfy the position condition of maintaining a position where the entire anti-input-side end 20a of the input shaft 20 and the recess 92 overlap when viewed axially during its operation. The power transmission device 10 of the present embodiment is configured to maintain a position where the entire first pinion 46 also overlaps the recess 92 in addition to the input shaft 20.

[0037] In order to satisfy the above-described positional conditions regarding the input shaft 20 and the concave portion 92, the power transmission device 10 of the present embodiment connects the casing body 82 that supports the input shaft 20 to the input-side carrier 34 in a non-rotatable manner. Thereby, during the operation of the power transmission device 10, the relative position in the circumferential direction between the input-side carrier 34 and the input shaft 20 does not fluctuate, and the above-described positional conditions can be satisfied. At this time, when viewed from the axial direction, if the entire first pinion 46 and the concave portion 92 are provided at positions overlapping in the axial direction, the same positional relationship can be maintained even during the operation of the power transmission device 10.

[0038] A part of the rotating body 22 of the present embodiment is disposed within the concave portion 92 of the input-side carrier 34. At least a part of the rotating body 22 is located on the anti-input side with respect to the input-side opening 92a of the concave portion 92 that opens to the input-side outer surface 94 of the input-side carrier 34. In the present embodiment, at least a part of the first restricting body 80 is disposed within the concave portion 92, and the input shaft 20 and the first pinion 46 are disposed outside the concave portion 92. In the present embodiment, each of the first bolt 86, the first washer 90, and the first restricting member 88, which are part of the first restricting body 80, is disposed within the concave portion 92. In addition to this, only the first bolt 86 may be disposed within the concave portion 92. Also, at least one of the input shaft 20 and the first pinion 46 may be disposed within the concave portion 92.

[0039] The first pinion 46 includes a plurality of first external teeth 46c provided on the outer peripheral portion of the first pinion 46. The first gear 50 includes a plurality of second external teeth 50a provided on the outer peripheral portion of the first gear 50. The plurality of first external teeth 46c mesh with the plurality of second external teeth 50a. The tooth width L46 of the first external teeth 46c is larger than the tooth width L50 of the second external teeth 50a. The second external teeth 50a are provided so as to be accommodated within an axial range where the first external teeth 46c are located when viewed from the radial direction of the rotating body 22. The second external teeth 50a are provided so as not to protrude outside the axial range of the first external teeth 46c. Thereby, edge contact of the edges at both axial ends of the first external teeth 46c with respect to the second external teeth 50a can be avoided.

[0040] The effects of the above-described power transmission device 10 will be described.

[0041] Refer to FIG. 4(A). Suppose, when viewed axially, there is no recess 92 in the input-side carrier 34 at the position overlapping the rotating body 22. In this case, a clearance 100 for avoiding interference between the input-side carrier 34 and the rotating body 22 in the axial direction of both is required. The clearance 100 needs to ensure at least the required axial dimension L100 in consideration of variations in position due to dimensional errors, assembly errors, etc.

[0042] In order to reduce the axial dimension of the power transmission device 10, it is desirable to shift the position of the rotating body 22 as much as possible to the anti-input side. However, when the input-side carrier 34 is arranged at the position overlapping the rotating body 22 when viewed axially, it is necessary to ensure at least a clearance 100 having the required axial dimension L100, and there is a limit even if the position of the rotating body 22 is shifted to the anti-input side. Hereinafter, the position with a clearance 100 of the required axial dimension left from the input-side side surface of the input-side carrier 34 without the recess 92 is referred to as the reference position P.

[0043] Refer to FIG. 4(B). In FIG. 4(B), for the sake of convenience of explanation, an example in which the recess 92 of the input-side carrier 34 is a bottomed recess is shown. The bottomed recess has a bottom without penetrating the input-side carrier 34 in the axial direction. On the input-side side surface of the input-side carrier 34 of the present embodiment, a recess 92 is provided at a position overlapping the entire anti-input side end portion 20a of the input shaft 20 when viewed axially. In the rotating body 22, the portion overlapping the entire anti-input side end portion 20a of the input shaft 20 when viewed axially is referred to as the first specific portion 102. In FIG. 4(B), the radial range of the rotating body 22 having the first specific portion 102 is schematically shown. In the illustrated example, in addition to the input shaft 20, the first bolt 86 and the first washer 90 of the first restricting body 80 are provided at the first specific portion 102 of the rotating body 22.

[0044] Suppose, as shown in FIG. 4(B), that the recess 92 of the input-side carrier 34 is a bottomed recess. In this case, the rotating body 22 can be shifted toward the non-input side from the reference position P until the clearance 100 between the first specific location 102 of the rotating body 22 and the bottom of the recess 92 becomes the required axial dimension L100. Further, even if the rotating body 22 is shifted in this way, since a clearance 100 with the required axial dimension L100 can be ensured between the first specific location 102 of the rotating body 22 and the bottom of the recess 92, interference in the axial direction between the first specific location 102 of the rotating body 22 and the input-side carrier 34 can be avoided. Next, although not shown, consider the case where the recess 92 of the input-side carrier 34 is a through-hole 96 as in the embodiment. In this case, even if the rotating body 22 is shifted toward the non-input side from the reference position P, interference between the first specific location 102 of the rotating body 22 and the input-side carrier 34 can be avoided.

[0045] In any case, by providing the input-side carrier 34 with the aforementioned recess 92, compared with the case where the input-side carrier 34 has no recess 92, it is advantageous for shifting the rotating body 22 toward the non-input side from the reference position P while avoiding interference in the axial direction between the first specific location 102 of the rotating body 22 and the input-side carrier 34. By shifting the rotating body 22 toward the non-input side from the reference position P in this way, the axial dimension of the casing body 82 that supports the rotating body 22 can be reduced so that the position of the input-side side surface 82a (see FIG. 1) of the casing body 82 is shifted toward the non-input side. As a result, the axial dimension of the power transmission device 10 can be reduced. That is, by providing the input-side carrier 34 with the aforementioned recess 92, it is advantageous for reducing the axial dimension of the power transmission device 10.

[0046] In this specification, in order to solve the problem of "··· making it advantageous", it is sufficient to be able to reduce the difficulty of realizing the matters mentioned, and the realization of those matters themselves is not essential. For example, when it is said that "making the axial dimension smaller is advantageous", it is sufficient to be able to reduce the difficulty of realizing the reduction of the axial dimension, and the realization of the reduction itself is not essential. In order to solve this problem, it is sufficient to provide the aforementioned recess 92 at least on the input side surface of the input side carrier 34, and the presence of the casing body 82 necessary for realizing the reduction of the axial dimension is not essential.

[0047] In order to continuously obtain the effect of the recess 92 of the input side carrier 34 described here during the operation of the power transmission device 10, the power transmission device 10 may be configured to maintain a position where the anti-input side end portion 20a of the input shaft 20 and the recess 92 overlap when viewed axially during its operation.

[0048] The recess 92 of the present embodiment is provided at a position that also overlaps the entire first pinion 46 in addition to the anti-input side end portion 20a of the input shaft 20 when viewed axially. In the rotating body 22, the portion that overlaps the entire first pinion 46 when viewed axially is referred to as a second specific portion 104. In FIG. 4(B), the radial range of the rotating body 22 having the second specific portion 104 of the rotating body 22 is schematically shown. At this time, for the same reason as described for the first specific portion 102 of the rotating body 22 described above, it is advantageous for shifting the rotating body 22 to the anti-input side with respect to the reference position P while avoiding axial interference between the second specific portion 104 of the rotating body 22 and the input side carrier 34. As a result, it is more advantageous for reducing the axial dimension of the power transmission device 10.

[0049] A part of the rotating body 22 is disposed in the recess 92 of the input side carrier 34. Thereby, compared with the case where the rotating body 22 is not disposed in the recess 92 of the input side carrier 34, the rotating body 22 can be shifted to the anti-input side while avoiding axial interference between the rotating body 22 and the input side carrier 34. As a result, it is more advantageous for reducing the axial dimension of the power transmission device 10.

[0050] At least a part of the first restricting body 80 is disposed within the recess 92 of the input-side carrier 34. Thereby, compared with the case where the first restricting body 80 is not disposed within the recess 92 of the input-side carrier 34, the rotating body 22 can be shifted toward the non-input side while avoiding axial interference between the first restricting body 80 and the input-side carrier 34. As a result, it is further advantageous for reducing the axial dimension of the power transmission device 10.

[0051] The tooth width L46 of the first pinion 46 is larger than the tooth width L50 of the first gear 50. When this relationship is satisfied, usually, the non-input side surface of the first pinion 46 is positioned more on the non-input side than the non-input side surface of the first gear 50 and closer to the input-side carrier 34 than the first gear 50. For this reason, when the input-side carrier 34 has no recess 92, axial interference between the first pinion 46 and the input-side carrier 34 is more likely to become a problem compared with the case where the tooth width L46 of the first pinion 46 is the same as the tooth width L50 of the first gear 50. On the premise of such a problem, the recess 92 of the input-side carrier 34 is provided at a position axially overlapping with the first pinion 46. Therefore, it is advantageous for shifting the rotating body 22 toward the non-input side while avoiding axial interference between the first pinion 46 and the input-side carrier 34 by the recess 92.

[0052] The recess 92 of the input-side carrier 34 is a through hole 96 that axially penetrates the input-side carrier 34. Thereby, compared with the case where the recess 92 is a bottomed recess, even if the rotating body 22 is largely shifted toward the non-input side from the reference position P, interference between the first specific portion 102 of the rotating body 22 and the input-side carrier 34 described above can be avoided. As a result, the rotating body 22 can be more easily shifted toward the non-input side from the reference position P, which is further advantageous for reducing the axial dimension of the power transmission device 10.

[0053] The through hole 96 is a crankshaft hole 64 through which the crankshaft 26 is inserted. Therefore, by using the original crankshaft hole 64 in the input-side carrier 34 as the recess 92, the axial dimension of the power transmission device 10 can be advantageously reduced as described above.

[0054] The power transmission device 10 includes a third gear set composed of an external gear 30 and an internal gear 32, in addition to the first gear set 48 and the second gear set 52 on the rotation transmission mechanism 24. That is, the power transmission device 10 can output from the output member 44 after reducing the rotation input to the input shaft 20 by a total of three stages of gear sets. When using a total of three stages of gear sets in this way, although a high total reduction ratio can be achieved by the entire power transmission device 10, compared with the cases of one stage and two stages of gear sets, the axial dimension of the power transmission device 10 tends to increase. Even in such a case, by providing the recess 92 in the input-side carrier 34 as described above, it is excellent in that the axial dimension of the power transmission device 10 can be advantageously reduced. Incidentally, when using three stages of gear sets in this way, for example, a total reduction ratio of about 300 can be achieved by the power transmission device 10.

[0055] (Second Embodiment) Refer to FIG. 5. In the following embodiments, among the components described in the first embodiment, the components not described below may have the same content applied as in the first embodiment.

[0056] The second pinion 56 of this embodiment is provided separately from the intermediate shaft 54. The second pinion 56 includes a second pinion hole 56a provided at the center of the second pinion 56. The intermediate shaft 54 is inserted into the second pinion hole 56a in a state of being press-fitted. The second pinion 56 is connected to the intermediate shaft 54 so as to be integrally rotatable by means of a key, spline, etc. The second pinion 56 of this embodiment is connected to the intermediate shaft 54 so as to be integrally rotatable using a key 112. The key 112 is fitted into a key groove 56b provided in the second pinion hole 56a of the second pinion 56 and a key groove 54a provided in the intermediate shaft 54. The power transmission device 10 includes a second restricting body 110 attached to the intermediate shaft 54. The second restricting body 110 is configured using bolts, restricting members, etc., similar to the first restricting body 80. The second restricting body 110 restricts the axial movement of the second pinion 56 by hitting the second pinion 56 from the anti-input side. Thereby, the second restricting body 110 prevents the second pinion 56 from detaching from the intermediate shaft 54.

[0057] Thus, the second pinion 56 is provided separately from the intermediate shaft 54. As a result, the outer diameter of the second pinion 56 can be increased compared to the case where the second pinion 56 is integrally provided by the same member as the intermediate shaft 54, and the reduction ratio of the second gear set 52 can be decreased. Consequently, in achieving a high overall reduction ratio using a total of three stages of gear sets, by decreasing the reduction ratio of the second gear set 52, the overall reduction ratio can be adjusted to be moderately decreased.

[0058] Next, deformation modes of each of the components described so far will be described.

[0059] The power transmission device 10 may be used as a power steering device that assists the steering operation of the wheels. The sorting type has been described as a specific type of the eccentric swing type reducer 14. This specific type is not particularly limited, and for example, a center crank type in which the crankshaft 26 is provided on the swing center C30a of the external gear 30 may be used.

[0060] The reducer casing 38 may constitute the fixing member 42, and the carriers 34 and 36 may constitute the output member 44. In this case, for example, after providing the input shaft 20 on the swing center C30a of the external gear 30, a concave portion 92 may be provided in the input-side carrier 34 that becomes the output member 44, and a casing body 82 may be connected to the reducer casing 38 that becomes the fixing member 42. In this case, even if the carriers 34 and 36 that become the output member 44 rotate, the relative position in the circumferential direction between the input-side carrier 34 and the input shaft 20 hardly changes. Therefore, during the operation of the power transmission device 10, the position condition of maintaining the position where the entire anti-input-side end portion 20a of the input shaft 20 overlaps with the concave portion 92 can be easily satisfied when viewed from the axial direction. In configuring to satisfy this position condition, it can also be said that the power transmission device 10 may provide the input shaft 20 on the swing center C30a of the external gear 30.

[0061] The recess 92 of the input-side carrier 34 may be provided at a position that overlaps only the entire anti-input-side end portion 20a of the input shaft 20 when viewed axially and does not overlap at least a part of the first pinion 46. The recess 92 may be a bottomed recess as shown in FIG. 4(B). The crankshaft 26 does not have to be inserted into the through-hole 96 that becomes the recess 92.

[0062] The rotating body 22 does not have to be arranged within the recess 92 of the input-side carrier 34 as shown in FIG. 4(B).

[0063] A specific example of the first regulating body 80 is not particularly limited. The first regulating body 80 may be, for example, a retaining ring or the like. The first washer 90 of the first regulating body 80 may be omitted. In addition to this, the first regulating member 88 may be constituted by the first bolt 86.

[0064] The tooth width L46 of the first pinion 46 may be set such that L46 ≤ the tooth width L50 of the first gear 50.

[0065] The rotation transmission mechanism 24 may include only the first gear set 48 and not include the second gear set 52. In this case, the power transmission device 10 decelerates the rotation of the input shaft 20 by a total of two gear sets and then outputs it from the output member 44. In this case, the first gear 50 of the first gear set 48 may be provided so as to be integrally rotatable with the crankshaft 26 instead of the intermediate shaft 54. In this case, when viewed axially, the first gear 50 and the input shaft 20 may be arranged at positions overlapping the crankshaft hole 64 that constitutes the recess 92 of the input-side carrier 34.

[0066] The second gear set 52 may be arranged on the anti-input side with respect to the anti-input-side carrier 36, or may be arranged between the anti-input-side carrier 36 and the input-side carrier 34. The second gear 58 of the second gear set 52 only needs to be provided on at least one of the plurality of crankshafts 26, and the number thereof is not particularly limited. When the number of the second gears 58 is singular, only one crankshaft 26 may be driven by the second pinion 56, and the other crankshafts 26 may be driven by the oscillation of the external gear 30.

[0067] The rotation transmission mechanism 24 may transmit the rotation of the rotating body 22 to the crankshaft 26 at a constant speed, or may increase the speed of the rotation of the rotating body 22 and transmit it to the crankshaft 26. An example in which the first gear set 48 is composed of a first gear and a second gear that mesh with each other, the first gear is a first pinion 46 with a small number of teeth, and the second gear is a first gear 50 with a large number of teeth has been described. The number of teeth of the first gear and the second gear may be the same, or the number of teeth of the first gear may be more than the number of teeth of the second gear. The second gear set 52 is composed of a third gear and a fourth gear that mesh with each other, and an example in which the third gear is a second pinion 56 with a small number of teeth and the fourth gear is a second gear 58 with a large number of teeth has been described. The number of teeth of the third gear and the fourth gear may be the same, or the number of teeth of the third gear may be more than the number of teeth of the fourth gear. When the number of teeth of the gears constituting each of the gear sets 48 and 52 is the same, the rotation of the rotating body 22 is transmitted to the crankshaft 26 at a constant speed. Regarding the number of teeth of each gear, when the first gear > the second gear and the third gear > the fourth gear, the rotation of the rotating body 22 is increased in speed and transmitted to the crankshaft 26.

[0068] The above embodiments and modified forms are examples. The technical ideas abstracted from these should not be construed as being limited to the contents of the embodiments and modified forms. Many design changes such as changes, additions, deletions, etc. of components are possible for the contents of the embodiments and modified forms. In the above-described embodiments, regarding the contents for which such design changes are possible, the notation "this form" is added for emphasis. However, design changes are also allowed for the contents without such notation. The hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached.

[0069] Any combination of the above components is also effective. For example, any explanatory matter of other embodiments may be combined with the embodiments, or any explanatory matter of the embodiments and other modified forms may be combined with the modified forms. A component configured by a single member in the embodiments may be configured by a plurality of members. Similarly, a component configured by a plurality of members in the embodiments may be configured by a single member.

Explanation of reference numerals

[0070] 10... Power transmission device, 12... Driving machine, 20... Input shaft, 22... Rotating body, 24... Rotational transmission mechanism, 26... Crankshaft, 28... Eccentric body, 30... External gear, 34... Carrier, 46... First pinion (first gear), 48... First gear set, 50... First gear (second gear), 52... Second gear set, 54... Intermediate shaft, 56... Second pinion (third gear), 58... Second gear (fourth gear), 92... Concave portion, 94... Input side outer surface, 96... Through hole.

Claims

1. A rotating body having an input shaft to which rotation is input from a drive machine, a crankshaft to which the rotation of the input shaft is transmitted via a rotation transmission mechanism, an external gear oscillated by an eccentric body of the crankshaft, and a carrier disposed on the input side in the axial direction with respect to the external gear, wherein the power transmission device includes: a recess is provided on the input side surface of the carrier at a position overlapping the entire anti-input side end of the input shaft when viewed axially.

2. The rotating body includes a first gear provided so as to be rotatable integrally with the input shaft, The power transmission device according to claim 1, wherein the recess is also provided at a position overlapping the entire first gear when viewed axially.

3. A second gear meshing with the first gear is provided, The power transmission device according to claim 2, wherein the tooth width of the first gear is larger than the tooth width of the second gear.

4. A part of the rotating body is disposed in the recess. The power transmission device according to claim 1.

5. The rotating body includes a first gear provided so as to be rotatable integrally with the input shaft and a restricting body attached to the input shaft for restricting axial movement of the first gear, The power transmission device according to claim 4, wherein at least a part of the restricting body is disposed in the recess.

6. The power transmission device according to claim 1, wherein the recess is a through hole penetrating the carrier in the axial direction.

7. The power transmission device according to claim 6, wherein the crankshaft is inserted into the through hole.

8. The rotating body includes a first gear provided so as to be rotatable integrally with the input shaft, The rotation transmission mechanism includes a second gear meshing with the first gear, The carrier includes an input side outer surface axially opposed to at least a part of the second gear, The power transmission device according to claim 1, wherein the recess is recessed on the anti-input side with respect to the input side outer surface.

9. The rotating body includes a first pinion provided so as to be rotatable integrally with the input shaft, The power transmission device according to claim 1, wherein the rotation transmission mechanism includes a first gear that forms a first gear set in combination with the first pinion and a second gear set provided on the output side of the rotation transmission path of the rotation transmission mechanism with respect to the first gear.

10. The second gear set includes a second pinion provided so as to be rotatable integrally with an intermediate shaft, The power transmission device according to claim 9, wherein the second pinion is provided separately from the intermediate shaft.

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