CN109751366B - Planetary gear speed reducer - Google Patents

Abstract

The invention provides a planetary gear speed reducer capable of improving transmission efficiency. The planetary gear reduction device is provided with: an internal gear (16); an external gear (14) meshed with the internal gear (16); a carrier (20) disposed on an axial side of the external gear (14); a pin member (22) that is supported by the carrier (20) and that synchronizes with the rotation component or revolution component of the external gear (14); and an oil seal (26) disposed between the carrier (20) and the housing (24), wherein the carrier (20) has: a press-in hole (46) into which the pin member (22) is pressed; and a suction hole (48) that communicates the space outside the wheel carrier (20) with the pressure inlet hole (46), wherein the centerline (Ld) of the suction hole (48) is located radially inward of the extension line (Lc') of the centerline (Lc) of the pressure inlet hole (46) in the axial range (S1) in which the oil seal (26) is disposed.

Description

Planetary gear speed reducer

The present application claims priority based on japanese patent application No. 2017-212938, applied on 11/2/2017. The entire contents of this Japanese application are incorporated by reference into this specification.

Technical Field

The present invention relates to a planetary gear reduction device.

Background

Patent document 1 discloses a planetary gear reduction device including: an internal gear; an outer gear engaged with the inner gear; a carrier disposed on an axial side of the outer gear; and a pin member supported by the wheel frame. The wheel frame generally has a press-fitting hole into which the pin member is press-fitted, and a suction hole through which air in the press-fitting hole is discharged when the pin member is press-fitted into the press-fitting hole. In the reduction gear of patent document 1, an extension line of a center line of the press-in hole and a center line of the air extraction hole are arranged on the same axis.

Patent document 1: japanese patent laid-open publication No. 2017-067276

The reduction gear of patent document 1 further includes: a housing integrated with the internal gear; and an oil seal disposed between the housing and the wheel carrier. When the housing and the carrier rotate relative to each other in conjunction with the rotation of the external gear, the oil seal slides on the outer surface of one of them (hereinafter, referred to as a sliding member). The present inventors have recognized that there are problems as follows: the smaller the reduction ratio of the reduction gear, the faster the relative rotational speed of the housing and the carrier becomes, and the greater the energy loss due to the sliding between the oil seal and the member to be slid becomes.

Disclosure of Invention

One embodiment of the present invention has been made in view of such a situation, and an object thereof is to provide a planetary gear reduction device capable of improving transmission efficiency.

One embodiment of the present invention relates to a planetary gear reduction device including: an internal gear; an external gear meshed with the internal gear; a carrier disposed on an axial side portion of the external gear; a pin member supported by the carrier and synchronized with a rotation component or a revolution component of the external gear; and an oil seal disposed between the wheel carrier and the housing, the wheel carrier having: the press-in hole is used for pressing in the pin part; and an air suction hole communicating an outer space of the wheel frame with the press-in hole, a center line of the air suction hole being located radially inward of an extension line of the center line of the press-in hole in an axial range in which the oil seal is disposed.

Another embodiment of the present invention relates to a planetary gear reduction device including: an internal gear; an external gear meshed with the internal gear; a carrier disposed on an axial side portion of the external gear; a pin member supported by the carrier and synchronized with a rotation component or a revolution component of the external gear; and an oil seal disposed between the wheel carrier and the housing, the wheel carrier having: the press-in hole is used for pressing in the pin part; and an air extraction hole that communicates the space outside the wheel carrier with the press-in hole, the air extraction hole communicating with the space outside the wheel carrier through an opening formed in an inner wall surface of a hollow portion formed in the wheel carrier or an opening formed in an outer peripheral surface of the wheel carrier, a center line of the air extraction hole being provided so as to avoid an axial range in which the oil seal is disposed.

According to the present invention, a planetary gear reduction device capable of improving transmission efficiency is provided.

Drawings

Fig. 1 (a) is a cross-sectional view showing a part of a wheel frame of a reference example, and fig. 1 (b) is a cross-sectional view showing a part of a wheel frame of embodiment 1.

Fig. 2 (a) is a cross-sectional view showing a part of a wheel frame of a reference example, and fig. 2 (b) is a cross-sectional view showing a part of a wheel frame of embodiment 2.

Fig. 3 is a side sectional view showing the reduction gear transmission according to embodiment 1.

Fig. 4 is an enlarged view showing a part of the non-input-side wheel carrier according to embodiment 1 and its peripheral structure.

Fig. 5 is a diagram showing the shapes of the pressure inlet hole and the suction hole in embodiment 1.

Fig. 6 is a diagram showing a flow of a machining method for obtaining the non-input-side wheel carrier according to embodiment 1.

Fig. 7 is a sectional view showing a part of a wheel frame according to modification 1.

Fig. 8 is a side sectional view showing a part of the reduction gear transmission of embodiment 2.

Fig. 9 is a front view schematically showing a part of the reduction gear transmission according to embodiment 3.

Fig. 10 is a cross-sectional view showing a part of a wheel frame according to modification 2.

In the figure: 10-planetary gear reduction unit, 14-external gear, 16-internal gear, 18, 20-wheel carrier, 22-pin component, 24-shell, 26-oil seal, 28-main bearing, 46-press-in hole, 48-suction hole, 50-main bearing opposite surface, 52-oil seal opposite surface and 64-hollow part.

Detailed Description

First, a description will be given of a background in which the planetary gear reduction device (hereinafter, simply referred to as a reduction device) of the present embodiment is conceived. In the case where the reduction ratio of the reduction gear is sufficiently large, the relative rotational speed of the housing and the carrier becomes very slow, and therefore the energy loss caused by the sliding between the oil seal and the slid member becomes very small. Therefore, it is widely believed that the energy loss due to the oil seal hardly affects the transmission efficiency of the reduction gear, and no special measures are taken to reduce the energy loss.

However, in recent years, a reduction gear device having a low reduction ratio has been increasingly demanded. As described above, if the reduction ratio of the reduction gear is reduced, the relative rotational speed of the casing and the carrier is increased. The present inventors have recognized that the energy loss due to the sliding between the oil seal and the sliding target member increases, and the influence on the transmission efficiency is of a level that cannot be ignored.

As a countermeasure, it is conceivable to reduce the inner diameter of the oil seal facing surface of the carrier facing the oil seal in the radial direction. However, the outer peripheral portion of the carrier including the oil seal facing surface needs to be thick enough to satisfy the required strength. Also, there is generally a press-in hole or a suction hole radially inside the oil seal facing surface. Therefore, the radial range from the oil seal facing surface to the press-in hole or the suction hole needs to secure a wall thickness that can satisfy the required strength, and therefore, it is also limited to reduce the inner diameter of the oil seal facing surface.

Fig. 1 (a) is a sectional view showing a part of a wheel carrier 200 according to a reference example, and fig. 1 (b) is a sectional view showing a part of a wheel carrier 20 according to embodiment 1. In the wheel carrier 200 of the reference example, the radial range from the oil seal facing surface 52 to the suction hole 48 ensures a wall thickness Ta that can satisfy the required strength.

As a countermeasure against the above problem, the following method is adopted in the reduction gear device of embodiment 1. That is, as shown in fig. 1 b, in the axial direction range S1 (hereinafter, simply referred to as the oil seal disposition range S1) in which the oil seal 26 is disposed, the center line Ld of the air suction hole 48 is located radially inward of an extension line (hereinafter, referred to as a center extension line) Lc' of the center line Lc of the press-in hole 46. In addition, the "center line" in the present specification refers only to a line passing through the center of the hole mentioned and extending from one end portion to the other end portion of the hole, and does not include an extended line linearly extending the line from the one end portion or the other end portion of the hole toward the outside.

Thus, the position of the air extraction hole 48 can be located radially inward, as compared with a configuration (hereinafter, referred to as a reference configuration) in which the center extension line Lc' of the press-fitting hole 46 is arranged coaxially with the center line Ld of the air extraction hole 48, as in the wheel carrier 200 of the reference example shown in fig. 1 (a). Thus, it is easy to design so that the thickness Tb equal to the thickness Ta of the reference structure can be secured in the outer peripheral portion of the carrier 20 in the oil seal disposition range S1, and the inner diameter of the oil seal facing surface 52 can be further reduced as compared with the reference structure.

Fig. 2 (a) is a sectional view showing a part of a wheel carrier 200 of a reference example, and fig. 2 (b) is a sectional view showing a part of a wheel carrier 20 of embodiment 2. As a countermeasure against the above problem, the following method is adopted in the reduction gear device of embodiment 2. That is, as shown in fig. 2 (b), an opening is formed in the inner wall surface of the hollow portion 64 formed in the wheel frame 20, and the air suction hole 48 communicates with the space outside the wheel frame 20 through the opening and the hollow portion 64. According to this structure, the center line Ld of the suction hole 48 is set so as to avoid the oil seal disposition range S1.

(A) Thus, the following design is easily achieved: in at least a part of the oil seal disposition range S1, the air extraction hole 48 is provided avoiding the region Ra radially outside the center extension line Lc' of the press-in hole 46. Thus, it is easy to design so that the thickness Tc equal to or greater than the thickness Ta of the reference structure can be secured in the outer peripheral portion of the carrier 20 in at least a part of the oil seal disposition range S1, and the inner diameter of the oil seal facing surface 52 can be reduced.

Therefore, in all of the reduction gears, a wall thickness that can satisfy the required strength can be secured in the outer peripheral portion of the carrier 20, and the diameter size of the oil seal 26 can be reduced in size. This can reduce the elastic repulsive force applied from the oil seal 26 to the sliding target member, and can reduce the energy loss due to the sliding between the oil seal 26 and the sliding target member. As a result, a decrease in transmission efficiency due to energy loss of the oil seal 26 can be suppressed, and transmission efficiency can be improved. In particular, since the smaller the reduction gear ratio of the reduction gear transmission 10 is, the greater the influence of the energy loss of the oil seal 26 on the transmission efficiency is, it is effective in that the transmission efficiency can be improved when the reduction gear ratio is small.

The air extraction hole 48 according to embodiment 2 is preferably provided in the oil seal disposition range S1 so as to avoid a region Ra radially outside the center extension line Lc' of the pressure insertion hole 46. Thus, the outer peripheral portion of the carrier 20 can have a thickness Tc equal to or greater than the thickness Ta of the reference structure over the entire oil seal disposition range S1, and the inner diameter of the oil seal facing surface 52 can be reduced.

In the following, in the embodiment and the modified examples, the same constituent elements are denoted by the same reference numerals, and redundant description thereof is omitted. In the drawings, for convenience of explanation, a part of the constituent elements is omitted as appropriate, or the dimensions of the constituent elements are enlarged or reduced as appropriate.

(embodiment 1)

Fig. 3 is a side sectional view showing the reduction gear transmission 10 according to embodiment 1. The reduction gear transmission 10 of the present embodiment is an eccentric oscillation type reduction gear transmission that oscillates an external gear meshing with an internal gear, rotates one of the internal gear and the external gear, and outputs a generated motion component from an output member.

The planetary gear reduction device 10 mainly includes an input shaft 12, an external gear 14, an internal gear 16, a carrier 18, a carrier 20, a pin member 22, a housing 24, an oil seal 26, and a main bearing 28. The main feature of the present embodiment is the wheel frame 20, but the description will be made first of all on the peripheral structure thereof. In the present embodiment, the output member that outputs rotational power to the driven device is the casing 24, and the carrier 20 is fixed to an external member that supports the reduction gear transmission 10. In the following description, a direction along the central axis La of the internal gear 16 is referred to as an "axial direction", and a circumferential direction and a radial direction of a circle centered on the central axis La are referred to as a "circumferential direction" and a "radial direction", respectively. Hereinafter, for convenience of explanation, one side in the axial direction (right side in the drawing) is referred to as an input side, and the other side in the axial direction (left side in the drawing) is referred to as an opposite-to-input side.

The input shaft 12 rotates around a rotation center line by rotational power input from the driving device 30. The reduction gear transmission 10 of the present embodiment is a center crank type reduction gear transmission in which the rotation center line of the input shaft 12 and the center axis line La of the internal gear 16 are disposed on the same axis. The driving device 30 is, for example, a motor, a gear motor, an engine, or the like.

The input shaft 12 of the present embodiment is a crankshaft having a shaft portion 12a extending in the axial direction and a plurality of eccentric portions 12b for oscillating the external gear 14. The plurality of eccentric portions 12b are provided so as to be rotatable integrally with the shaft portion 12 a. The axial center Lb of the eccentric portion 12b is eccentric with respect to the rotation center of the input shaft 12 (i.e., the central axis La of the internal gear 16). The phases of the eccentric directions of the plurality of eccentric portions 12b are shifted from each other. In the present embodiment, two eccentric portions 30b are provided, and the eccentric phase difference of the two eccentric portions 30b is 180 degrees.

The external gears 14 are provided independently corresponding to the respective eccentric portions 12 b. The external gear 14 is rotatably supported by the corresponding eccentric portion 12b via an eccentric bearing 32.

The outer gear 14 meshes with the inner gear 16. The internal gear 16 of the present embodiment includes a plurality of outer pins 16a supported by an inner peripheral portion of the housing 24 and constituting internal teeth of the internal gear 16. In the present embodiment, the number of internal teeth of the internal gear 16 (the number of outer pins 16 a) is one more than the number of external teeth of the external gear 14.

The housing 24 is integrated with the internal gear 16, and is cylindrical as a whole. The housing 24 of the present embodiment includes: a 1 st member 24a integrated with the internal gear 16; and a 2 nd member 24b disposed on the opposite side of the input side from the 1 st member 24a and integrated with the 1 st member 24a by a bolt. The input cover 34 disposed on the input side with respect to the housing 24 is integrated with the housing 24 by bolts.

The carriers 18, 20 include an input-side carrier 18 disposed on the side of the input side of the external gear 14 and an opposite-input-side carrier 20 disposed on the side of the opposite input side of the external gear 14. The wheel frames 18, 20 are made of, for example, a metal-based material or a resin-based material. The metal-based material includes, for example: cast iron, steel-based materials including steel, and aluminum-based materials including aluminum alloys. The resin material includes a composite material such as a carbon fiber-reinforced resin or a glass fiber-reinforced resin, in addition to engineering plastics and the like. A 1 st input shaft bearing 36 is disposed between the input side carrier 18 and the input shaft 12. The input-side carrier 18 rotatably supports the input shaft 12 via a 1 st input shaft bearing 36. A 2 nd input shaft bearing 38 is disposed between the input-side carrier 20 and the input shaft 12. The input-side carrier 20 rotatably supports the input shaft 12 via the 2 nd input shaft bearing 38.

The pin member 22 axially penetrates the external gear 14 at a position radially offset from the axial center of the external gear 14. The pin member 22 is provided in plurality at intervals around the center axis La of the internal gear 16. The external gear 14 is formed with pin holes 14a through which the pin members 22 pass, corresponding to the respective pin members 22. A gap is provided between the pin member 22 and the pin hole 14a, which serves to absorb the play of the oscillation component of the external gear 14.

The pin member 22 is press-fitted into a press-fitting hole 46 (described later) of the input-side carrier 20, and is fixed and supported by the input-side carrier 20. The pin members 22 of the present embodiment are press-fitted into the pin holes 18a of the input-side wheel carrier 18 and fixed to the input-side wheel carrier 18, and the pin members 22 function as wheel carrier pins that connect the wheel carrier 18 and the wheel carrier 20. A roller 44 rotatably supported by the pin member 22 is provided on the outer peripheral side of the pin member 22.

The main bearing 28 is disposed between the wheel carriers 18, 20 and the casing 24. The main bearing 28 of the present embodiment is a rolling bearing such as a ball bearing. The member of the wheel frames 18 and 20 and the casing 24 fixed to the external member is referred to as a fixed member. At this time, the output member is rotatably supported by the fixed member via the main bearing 28. The output member of the present embodiment is the case 24, and the fixed member is the input-side carrier 20.

The oil seal 26 is disposed between the input-side reverse carrier 20 and the housing 24. The oil seal 26 is formed of an annular elastic body. The oil seal 26 is attached to one of the input-side carrier 20 and the housing 24 (hereinafter referred to as an attached member) by fitting such as interference fit or transition fit. When the housing 24 and the input-side reverse carrier 20 relatively rotate, the oil seal 26 slides on the outer surface of the slid-on member as the other of them. The mounted member of the present embodiment is the case 24, and the slid member is the input-side wheel carrier 20.

The seal lip portion of the oil seal 26 is brought into contact with the outer surface of the member to be slid by elastic deformation, thereby sealing the internal space 40 in which the external gear 14 and the like are accommodated. Although not shown, the internal space 40 communicates with an internal space of the drive device 30 connected to the input cover 34, and is isolated from an external space 42. The internal space 40 is filled with a lubricating oil (not shown) for lubricating the meshing portion between the external gear 14 and the internal gear 16.

Next, the operation of the reduction gear transmission 10 will be described. When the rotational power is transmitted from the drive device to the input shaft 12, the eccentric portion 12b of the input shaft 12 rotates around the central axis La of the internal gear 16, and the eccentric portion 12b causes the external gear 14 to oscillate. At this time, the external gear 14 oscillates such that its axial center rotates around the central axis La of the internal gear 16. When the external gear 14 oscillates, the meshing positions of the external gear 14 and the internal gear 16 sequentially shift. As a result, one of the external gear 14 and the internal gear 16 self-transmits an amount corresponding to the difference in the number of teeth between the external gear 14 and the internal gear 16 every time the input shaft 12 rotates once.

When the case 24 is an output member and the input-side carrier 20 is fixed to an external member as in the present embodiment, the external member restricts the rotation of the external gear 14 via the pin member 22, and the internal gear 16 rotates. On the other hand, when the input-side carrier 20 is an output member and the housing 24 is fixed to an external member, the external member restricts the rotation of the internal gear 16 via the housing 24, and therefore the external gear 14 rotates. The rotation of the input shaft 12 is decelerated at a reduction gear ratio corresponding to the difference in the number of teeth between the external gear 14 and the internal gear 16, and is output from the output member to the driven device.

Here, since the pin member 22 axially penetrates the external gear 14, the pin member 22 can synchronize with the rotation component of the external gear 14. Here, "synchronized with the rotation component of the external gear 14" means: when the rotation of the external gear 14 is restricted as in the present embodiment, the pin member 22 is maintained in a state of not revolving. On the other hand, "synchronized with the rotation component of the external gear 14" means again: the pin member 22 revolves around the central axis La of the internal gear 16 in conjunction with the rotation of the external gear 14, without restricting the rotation of the external gear 14. In any case, it is considered that the rotation component of the external gear 14 and the revolution component of the pin member 22 are maintained at the same size in the numerical range including zero.

Fig. 4 is an enlarged view showing a part of the input-side wheel carrier 20 and its peripheral structure. The input-side opposite-side carrier 20 mainly has a press-in hole 46, a suction hole 48, a main bearing opposed surface 50, and an oil seal opposed surface 52.

The press-in hole 46 is a bottomed hole that is bored on the side of the external gear 14 in the axial direction of the input-side opposite side carrier 20. The pin member 22 is press-fitted into the press-fitting hole 46. The pin member 22 is press-fitted into the press-fitting hole 46 in a state where its outer peripheral surface is in contact with the inner peripheral surface of the press-fitting hole 46. The press-fitting hole 46 of the present embodiment is provided such that the center line Lc extends linearly in the axial direction. The press-in holes 46 correspond to the respective pin members 22 and are provided in plural at intervals from each other around the central axis La of the internal gear 16.

The suction hole 48 communicates the outer space 41 of the input-side wheel carrier 20 with the press-in hole 46. Here, the "outer space 41" refers to a space provided outside the wheel carrier (in this example, the input-side wheel carrier 20) mentioned above, and both the inner space 40 inside the reduction gear unit 10 and the outer space 42 outside the reduction gear unit 10 belong to the category of the outer space 41. The "outer space 41" in the present embodiment is the outer space 42. The suction holes 48 have the following functions: when the pin member 22 is press-fitted into the press-fitting hole 46, air in the press-fitting hole 46 is discharged to the outer space 41. The extraction hole 48 of the present embodiment opens to the inner wall surface of the press-fitting hole 46 (i.e., the bottom surface of the press-fitting hole 46). The air extraction hole 48 of the present embodiment is provided linearly in the axial direction, and opens toward the side of the input-side carrier 20 opposite to the external gear 14 in the axial direction.

The center line Ld of the air suction hole 48 of the present embodiment is provided linearly in the axial direction, and is parallel to the center extension line Lc' of the press-in hole 46. Here, "parallel" includes a case where the two are substantially parallel to each other, in addition to a case where the two are literally completely parallel to each other.

The cross-sectional area of the pressure hole 46 in the cross section perpendicular to the center line Lc is Sa, and the cross-sectional area of the suction hole 48 in the cross section perpendicular to the center line Ld is Sb. At this time, the sectional area Sb of the suction hole 48 is set smaller than the sectional area Sa of the press-in hole 46.

Fig. 5 is a view showing the shapes of the press-fitting hole 46 and the air-extracting hole 48 when viewed from the opposite side to the input side in the axial direction. In the present embodiment, the cross-sectional shape of the press-fitting hole 46 is circular, and the cross-sectional shape of the air-extracting hole 48 is circular.

Returning to fig. 4, the main bearing opposing surface 50 is radially opposite the main bearing 28. The oil seal facing surface 52 is radially opposed to the oil seal 26. In the present embodiment, the inner ring of the main bearing 28 contacts the main bearing facing surface 50, and the seal lip portion of the oil seal 26 contacts a part of the oil seal facing surface 52. The oil seal facing surface 52 of the present embodiment is set to have a smaller outer diameter than the main bearing facing surface 50.

Here, the center line Ld of the air suction hole 48 is located radially inward of the center extension line Lc' of the press-fitting hole 46 in the oil seal disposition range S1. This condition may be satisfied at least in a part of the oil seal disposition range S1. That is, the positional relationship between the center line Ld of the suction hole 48 and the center extension line Lc' of the press-fitting hole 46 in the portion axially deviated from the oil seal disposition range S1 is not limited. The center line Ld of the air extraction hole 48 of the present embodiment is located radially inward of the center extension line Lc' of the press-fit hole 46 over the entire axial range of the air extraction hole 48. As a result, as described above, the outer peripheral portion of the input-side carrier 20 can be ensured with a thickness that can satisfy the required strength, and the diameter of the oil seal 26 can be reduced in size.

The oil seal facing surface 52 of the input-side opposite carrier 20 is set to have an outer diameter smaller than the outer diameter of the main bearing facing surface 50. Therefore, as compared with the case where this condition is not satisfied, the outer diameter of the oil seal facing surface 52 can be reduced, and further, the diameter dimension of the oil seal 26 can be further reduced. This can further reduce energy loss due to sliding between the oil seal 26 and the sliding target member, and can further improve transmission efficiency.

Fig. 6 is a diagram showing a flow of a machining method of the input-side wheel carrier 20. In this machining method, first, as shown in fig. 6 (a), the contra-input-side wheel carrier 20 in which the press-in hole 46 and the suction hole 48 are not formed is prepared. Next, rough cutting is performed by a cutting tool 54 such as a drill to form a through hole at a predetermined position where the press-fit hole 46 and the extraction hole 48 are formed. Fig. 6 (a) shows the formation-scheduled positions Pa of the through-holes.

Fig. 6 (b) shows a through-hole 56 obtained by rough cutting. The portion 56a of the through hole 56 on the opposite side to the input side serves as the suction hole 48, and the center line Le of the through hole 56 serves as the center line of the suction hole 48. The other side portion 56b of the through hole 56, which is located on the opposite side of the one side portion 56a in the axial direction, becomes a pre-drilled hole 58 of the press-in hole 46. The extraction hole 48 and the pilot hole 58 of the press-fit hole 46 can be formed together by one step of cutting the input-side carrier 20 from the external gear side (right side in the drawing) toward the side opposite to the external gear (left side in the drawing). Here, the external gear side refers to a side in the axial direction on which the external gears 14 exist, and the opposite side to the external gear side refers to a side in the axial direction opposite to the side on which the external gears 14 exist.

In general, high dimensional accuracy is required for the inner peripheral surface of the press-fitting hole 46 into which the pin member 22 is press-fitted. Therefore, it is necessary to finish the through-hole 56 obtained by the rough cutting process to ensure the dimensional accuracy of the press-in hole 46. In performing such finishing, it is generally necessary to form the pilot hole 58 in advance such that the centerline Le of the pilot hole 58 is located at a position Pb at which the centerline of the press-in hole 46 is to be provided (hereinafter, referred to as a predetermined centerline position Pb).

Therefore, as shown in fig. 6 (c), in order to displace the center line Le of the pilot hole 58 of the press-fitting hole 46 obtained by the rough cutting to the predetermined center line Pb of the press-fitting hole 46, the hole expanding process of expanding the diameter of the pilot hole 58 of the press-fitting hole 46 is performed. The hole expanding process is performed by using a cutting tool 60 that can cut the inner wall surface of the pilot hole 58 by its rotation. The cutting tool 60 is, for example, an end mill or the like. In this hole enlarging process, a cutting tool 60 is inserted into the pre-drilled hole 58 of the press-fit hole 46 obtained by the rough cutting process. In this state, the inner wall surface of the pilot hole 58 is cut by the rotation of the cutting tool 60 so that the center line Le of the pilot hole 58 is displaced to the predetermined center line position Pb of the press-in hole 46.

Fig. 6 (d) shows the pre-drilled hole 58 pressed into the hole 46 by the hole-enlarging process. As a result of the hole enlarging process, a pre-drilled hole 58 of the press-in hole 46 having a diameter larger than that of the suction hole 48 is formed adjacent to the suction hole 48 in the axial direction.

Next, the finish machining is performed by a finish machining tool 62 capable of machining with a higher machining accuracy than the cutting tool 54 used for the rough cutting, and the inner diameter of the pre-drilled hole 58 of the press-in hole 46 is enlarged. Here, the finishing tool 62 is a tool capable of cutting the inner wall surface of the pre-drilled hole 58 by rotating itself. The finishing tool 62 is, for example, a boring cutter, a reamer, or the like. In this finishing, a finishing tool 62 is inserted into the pre-drilled hole 58 pressed into the hole 46. In this state, the finishing tool 62 is rotated to cut the inner wall surface of the pre-drilled hole 58. Thus, the entire circumference of the inner wall surface of the pilot hole 58 of the press-fit hole 46 is finished, and the inner wall surface of the press-fit hole 46 with high dimensional accuracy is formed.

Here, as shown in fig. 4, the center extension line Lc' of the press-in hole 46 is parallel to the center line Ld of the suction hole 48. Therefore, the pilot hole 58 and the extraction hole 48 of the press-in hole 46 can be formed by rough cutting without changing the direction of the cutting tool 54, and therefore, good operability can be obtained by rough cutting.

As shown in fig. 5, the air extraction hole 48 of the present embodiment is provided such that the entire air extraction hole falls inside the inner wall surface of the press-in hole 46 when viewed from the axial direction. Here, "to fall inside the inner wall surface of the press-in hole 46" also includes the following cases: the contour of the inner wall surface of the extraction hole 48 does not protrude outward from the contour of the inner wall surface of the press-fit hole 46 and overlaps therewith. Therefore, the pre-drilled holes 58 of the extraction hole 48 and the press-fit hole 46 can be formed by one rough cutting, and thus the number of processing steps can be reduced.

The air-extracting hole 48 of the present embodiment is provided with an inner wall surface spaced apart from an inner wall surface of the press-fitting hole 46 when viewed from the axial direction. This means that: when viewed in the axial direction, the contour of the inner wall surface of the extraction hole 48 and the contour of the inner wall surface of the press-fit hole 46 do not overlap and are separated from each other. Therefore, after the preliminary drilled holes 58 of the extraction hole 48 and the press-in hole 46 are formed by the rough cutting process, the finishing process of enlarging the inner diameter of the preliminary drilled holes 58 of the press-in hole 46 over the entire circumference thereof can be performed. Therefore, high dimensional accuracy can be ensured over the entire inner wall surface of the press-fitting hole 46.

Further, in the case where the extended line of the center of the press-in hole and the center line of the extraction hole are provided on the same axis as each other as in the conventional structure, the hole can be formed only by rough cutting and finish machining without performing the above-described hole expanding process. This means that: compared to the above-described reference structure, the structure of the input-side reverse wheel carrier 20 according to the present embodiment can be realized by further performing a hole expanding process.

(modification 1)

Fig. 7 is a cross-sectional view showing a part of the non-input-side wheel carrier 20 according to modification 1. In fig. 4, an example in which the inner diameter of the press-fitting hole 46 is constant is described. The press-fitting hole 46 of the present modification includes a 1 st inner diameter portion 46a having a constant inner diameter into which the pin member 22 is press-fitted, and a 2 nd inner diameter portion 46b provided on the bottom side of the 1 st inner diameter portion 46 a. The 2 nd inner diameter portion 46b is formed to have a smaller inner diameter than the 1 st inner diameter portion 46 a. The 1 st inner diameter portion 46a is obtained by, for example, performing the above-described finishing on a part of a pre-drilled hole obtained by rough cutting. The 2 nd inner diameter portion 46b is obtained by leaving a part of the pre-drilled hole as it is without performing finish machining.

The air extraction hole 48 of the present modification is different from that of embodiment 1, and although not shown, the air extraction hole 48 of the present modification is provided such that a part thereof protrudes outward from the inner wall surface of the press-fitting hole 46 when viewed from the axial direction. The suction hole 48 of the present modification communicates with the press-in hole 46 through an opening 48a provided in the bottom surface thereof. The opening 48a opens on a conical surface provided on the bottom surface of the press-in hole 46 or on a conical surface provided on the bottom surface of the suction hole 48.

The extraction hole 48 of the present modification is obtained by cutting the input-side carrier 20 from the side opposite to the external gear toward the external gear side by the cutting tool 54 used for the rough cutting, for example. The configuration of the present modification requires rough cutting for obtaining the suction hole 48 in addition to rough cutting and finish cutting for obtaining the press-in hole 46. Compared with the reference structure, the structure of the present modification needs to be realized by performing a plurality of rough cutting processes.

(embodiment 2)

Fig. 8 is a side sectional view showing a part of the reduction gear transmission 10 according to embodiment 2. The reduction gear transmission 10 differs from the above-described embodiment mainly in the air suction hole 48.

The non-input-side wheel carrier 20 has the hollow portion 64 in addition to the above-described press-in hole 46. The hollow portion 64 of the present embodiment is a bottomed hole that opens toward the side opposite to the external gear, communicates with the outer space 41 (the external space 42), and is closed on the external gear side. The hollow portion 64 of the present embodiment functions as a lightening hole for the purpose of reducing the weight of the input-side carrier 20. When a virtual circle inscribed in the press-fitting hole 46 and centered on the central axis La of the internal gear 16 is assumed to be Ca, the hollow portion 64 of the present embodiment is provided so as to be located radially inward of the virtual circle Ca when viewed from the axial direction. The hollow portion 64 of the present embodiment is provided so as to pass through the central axis La of the internal gear 16. Fig. 8 shows a portion intersecting the imaginary circle Ca in a cross section of the reduction gear transmission 10 along the axial direction. The same applies to the imaginary circle Cb to be described below.

The suction hole 48 communicates with the press-fitting hole 46 through a 1 st opening 46c formed in the inner wall surface of the press-fitting hole 46, and communicates with the outer space 41 of the non-input-side wheel carrier 20 through a 2 nd opening 64a formed in the inner wall surface of the hollow portion 64 and the hollow portion 64. The suction hole 48 communicates the outside space 41 with the press-in hole 46. Thus, the air suction hole 48 functions to discharge air in the press-fitting hole 46 when the pin member 22 is press-fitted into the press-fitting hole 46. The center line Ld of the air extraction hole 48 of the present embodiment is provided obliquely with respect to the axial direction. Specifically, the center line Ld of the extraction hole 48 is inclined so as to be closer to the radially inner side as it becomes farther from the external gear 14 in the axial direction.

The center line Ld of the air suction hole 48 is provided avoiding the oil seal disposition range S1. The air extraction hole 48 may be provided such that the center line Ld thereof avoids the oil seal disposition range S1. It can also be said that the center line Ld of the suction hole 48 is provided so as not to overlap the oil seal disposition range S1, in other words, the oil seal 26, as viewed in the radial direction. The air extraction hole 48 of the present embodiment is provided in the oil seal disposition range S1 so as to avoid the region Ra radially outside the center extension line Lc' of the pressure insertion hole 46. The hollow portion 64 of the present embodiment also satisfies the same conditions. In the present embodiment, the 2 nd opening 64a is provided so as not to overlap the oil seal disposition range S1 as viewed in the radial direction.

Cb is an imaginary circle passing through the center line Lc of the press-fitting hole 46 with the center axis La of the internal gear 16 as the center. The imaginary circle Cb passes through a center extension line Lc 'having the smallest radius from the center axis La of the internal gear 16 among center extension lines Lc' of the plurality of press-in holes 46. When the above is understood from another point of view, the air extraction hole 48 may be provided in the oil seal disposition range S1 so as to avoid the region Ra radially outside the imaginary circle Cb. To achieve this, the suction hole 48 of the present embodiment is provided so as to communicate with the hollow portion 64 provided on the radially inner side of the region Ra and to pass through a position avoiding the region Ra.

As a result, as described above, the outer peripheral portion of the input-side carrier 20 can be ensured with a thickness that can satisfy the required strength, and the diameter of the oil seal 26 can be reduced in size.

The air extraction hole 48 of the present embodiment is also provided so as to avoid the regions Ra and Rb on the outside in the radial direction of the virtual circle Ca having a smaller diameter than the virtual circle Cb in the oil seal disposition range S1. The hollow portion 64 of the present embodiment also satisfies the same conditions.

Next, an example of a machining method of the non-input-side wheel carrier 20 will be described. First, the contra-input side wheel carrier 20 in which the hollow portion 64 is formed but the press-in hole 46 and the suction hole 48 are not formed is prepared. Next, the cutting tool 54 performs the 1 st rough cutting process for forming the pilot hole at the predetermined formation position of the press-in hole 46 and the 2 nd rough cutting process for forming the air-extracting hole 48 at the predetermined formation position of the air-extracting hole 48. Next, the finishing tool 62 performs finishing to enlarge the inner diameter of the pilot hole 58 of the press-in hole 46. As described above, the structure of the wheel frame 20 according to the present embodiment can be realized by performing rough cutting a plurality of times, as compared with the above-described reference structure.

(embodiment 3)

Fig. 9 is a front view schematically showing a part of the reduction gear transmission 10 according to embodiment 3. The reduction gear transmission 10 of the present embodiment is a simple planetary gear reduction gear transmission that rotates an external gear meshed with an internal gear to revolve the external gear or rotate the internal gear and outputs a generated motion component from an output member.

The reduction gear transmission 10 includes: a sun gear 66 that rotates integrally with the input shaft 12; a plurality of external gears 14 as planetary gears, which mesh with the sun gear 66; and an internal gear 16 meshed with the external gear 14. The pin member 22 axially penetrates the axial center of the external gear 14 and is supported by the pair of not-shown carriers 18 and 20. The pin member 22 rotatably supports the external gear 14 via a bearing 68. In the case of a simple planetary gear reduction device, the input-side carrier 20 (not shown) also includes press-fitting holes 46 and air-extracting holes 48 similar to those of embodiment 1.

The operation of the reduction gear transmission 10 will be described below. When rotational power is transmitted from the drive device to the input shaft 12, the sun gear 66 rotates integrally with the input shaft 12, and the external rotation gear 14 rotates. When the external gear 14 rotates, the meshing positions of the external gear 14 and the internal gear 16 sequentially shift, and revolution of the external gear 14 or rotation of the internal gear 16 occurs. When the housing 24 is an output member and the carrier 20 is fixed to an external member, the external member regulates the revolution of the external gears 14 via the pin members 22, and therefore the internal gears 16 rotate. On the other hand, when the carriers 18 and 20 are output members and the housing 24 is fixed to an external member, the external member restricts the rotation of the internal gear 16 via the housing 24, and therefore the external gear 14 revolves orbitally. The rotation of the input shaft 12 is decelerated at a reduction gear ratio corresponding to the number of teeth of the external gear 14, the internal gear 16, and the sun gear 66, and is output from the output member to the driven device.

Here, since the pin member 22 axially penetrates the external gear 14, the pin member 22 can synchronize with the revolution component of the external gear 14. Here, "synchronized with the revolution component of the external gear 14" means that: the pin member 22 is maintained in a state of not revolving while the revolution of the outer gear 14 is restricted; the pin member 22 revolves around the central axis La of the internal gear 16 in conjunction with the revolution of the external gear 14 without restricting the revolution of the external gear 14. In any case, it is considered that the revolution component of the external gear 14 and the revolution component of the pin member 22 are maintained at the same size in the numerical range including zero.

The planetary gear reduction device 10 is described above as an example of an eccentric oscillating type reduction device or a simple planetary gear reduction device, but the type thereof is not limited to these. In the case of a simple planetary gear reduction device, as in the example of fig. 8, the press-fitting hole 46 and the hollow portion 64 may be communicated with each other through the air-extracting hole 48.

In addition, in embodiment 1 and embodiment 2, an example of an eccentric oscillating type reduction gear device in which the eccentric oscillating type reduction gear device is a center crank type is described. In addition, the present invention can be applied to a distributed eccentric rocking type reduction gear device in which a plurality of input shafts are arranged at positions offset from the central axis of the internal gear.

Further, in embodiment 1 and embodiment 2, the case where the output member is the case 24 and the carrier 20 is fixed to the external member has been described, but the carrier 20 may be the output member and the case 24 may be fixed to the external member.

The embodiments of the present invention have been described in detail above. The above embodiments are merely specific examples for carrying out the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and a plurality of design changes such as changes, additions, deletions, and the like of the constituent elements can be made without departing from the scope of the inventive concept defined in the claims. In the above-described embodiment, the description has been given with the addition of a mark such as "in the embodiment" or "in the embodiment" to the content that can be subjected to such a design change, but this does not mean that the design change is not permitted without the content of such a mark. The hatching given on the cross section of the drawing is not intended to limit the material of the object to which the hatching is given.

Although the pin member 22 has been described as an example of functioning as a wheel carrier pin for connecting the pair of wheel carriers 18 and 20, the pin member 22 may not function as a wheel carrier pin. At this time, the pair of wheel frames 18, 20 are coupled together by wheel frame bolts or the like. When the carriers 18 and 20 are output members, the pin members 22 function as inner pins that transmit the rotation component or revolution component of the external gear 14 to the carriers 18 and 20. The pin member 22 may be formed integrally with one of the pair of wheel frames 18, 20, or may be a part of the same member as the one of the pair of wheel frames 18, 20. At this time, the pin member 22 may be press-fitted into the press-fitting hole 46 formed in the other wheel frame 18, 20.

Although the example in which the oil seal 26 is disposed between the housing 24 and the input-side carrier 20 has been described above, the oil seal 26 may be disposed between the housing 24 and the input-side carrier 18. The housing 24 may be a member to which the oil seal 26 is attached, the carriers 18 and 20 may be members to be slid on which the oil seal 26 is slid, the carriers 18 and 20 may be members to be attached, and the housing 24 may be a member to be slid.

The position and shape of the air extraction hole 48 are not particularly limited as long as they satisfy any of the following 1 st and 2 nd conditions. Here, the 1 st condition means: as shown in the example of fig. 4, in the oil seal disposition range S1, the center line Ld of the air suction hole 48 is disposed radially inward of the center extension line Lc' of the press-fitting hole 46. And, the 2 nd condition means: as shown in the example of fig. 8, the center line Ld of the suction hole 48 is set so as to avoid the oil seal disposition range S1.

When the condition 1 is satisfied, the center line Ld of the air extraction hole 48 may be disposed in at least a partial range of the oil seal disposition range S1. The center line Ld of the suction hole 48 may be curved as follows, for example: extends in the axial direction in a partial range of the oil seal disposition range S1 and extends radially inward in the middle of the oil seal disposition range S1. At this time, the suction hole 48 may communicate with the outer space 41 of the wheel frame 20 through the hollow portion 64 of the wheel frame 20.

As shown in fig. 10, the same effect as (a) described above can be obtained by communicating the air extraction hole 48 with the outer space 41 (inner space 40) of the carrier 20 through the 3 rd opening 20a formed in the outer peripheral surface of the carrier 20. The 3 rd opening 20a of the present embodiment is formed in the outer peripheral surface of the carrier 20 in the axial range between the oil seal 26 and the main bearing 28. In addition, although not shown, the air extraction hole 48 may communicate with the internal space 40 of the carrier 20 through an opening formed in the external gear side surface of the carrier 20. At this time, the suction hole 48 communicates with the internal space 40 of the wheel frame 20 without passing through the hollow portion 64 of the wheel frame 20. In short, the center line Ld of the air extraction hole 48 may be provided so as to avoid the oil seal disposition range S1.

In the present embodiment, the example of the bottomed hole in which the hollow portion 64 is open to the opposite side of the external gear and the external gear side is closed has been described, but the hollow portion 64 may be a through hole that is open to both the opposite side of the external gear and the external gear side. Alternatively, the hollow portion 64 may be a bottomed hole that is closed on the side opposite to the external gear and opens toward the external gear side to communicate with the outer space 41 (the internal space 40). At this time, the suction hole 48 communicates with the internal space 40 of the reduction gear transmission 10 through the hollow portion 64 of the wheel carrier 20, and communicates the internal space 40 of the reduction gear transmission 10 with the press-fitting hole 46.

Although the example in which the inner wall surface of the air hole 48 is provided with the gap between the inner wall surface of the air hole 48 and the inner wall surface of the press-fit hole 46 when viewed from the axial direction has been described above, the inner wall surface of the air hole 48 may overlap a part of the inner wall surface of the press-fit hole 46.

The outer diameter of the oil seal facing surface 52 may be set to be the same as the outer diameter of the main bearing facing surface 50 or larger than the outer diameter of the main bearing facing surface 50.

Although the hollow portion 64 has been described as an example functioning as a lightening hole, the function thereof is not particularly limited.

Claims (5)

1. A planetary gear reduction device is provided with:

an internal gear;

an external gear meshed with the internal gear;

a carrier disposed on an axial side portion of the external gear;

a pin member supported by the carrier and synchronized with a rotation component or a revolution component of the external gear; and

an oil seal disposed between the wheel carrier and the housing,

the planetary gear reduction unit is characterized in that,

the wheel carrier is provided with: the press-in hole is used for pressing in the pin part; and an air exhaust hole for communicating the outer space of the wheel frame with the press-in hole,

the center line of the suction hole is located radially inward of an extension line of the center line of the pressure inlet hole in an axial range in which the oil seal is disposed.

2. A planetary gear reduction unit according to claim 1,

and the extension line of the central line of the press-in hole is parallel to the central line of the air suction hole.

3. A planetary gear reduction unit according to claim 2,

the suction hole is provided so that the entirety thereof falls inside the inner wall surface of the press-in hole as viewed in the axial direction.

4. A planetary gear reduction unit according to claim 3,

the air extraction hole is provided with an inner wall surface and an inner wall surface of the press-in hole at a distance when viewed from the axial direction.

5. The planetary gear reduction unit according to any one of claims 1 to 4,

the planetary gear reduction device further includes a main bearing disposed between the carrier and the housing,

the wheel carrier is provided with: a main bearing opposed surface opposed to the main bearing in a radial direction; and an oil seal opposed surface opposed to the oil seal in a radial direction,

the outer diameter of the opposite surface of the oil seal is smaller than that of the opposite surface of the main bearing.

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