speed reducer

Abstract

To take sufficient measures for heat radiation in a speed reducer.SOLUTION: A speed reducer includes: a worm wheel (24) which is attached to an intermediate shaft (18) rotatably supported by a housing (12) and transmits rotation of a motor to the intermediate shaft (18); an input parallel gear (32) which transmits rotation of the intermediate shaft (18) to an output shaft (16); and a first heat radiation collar (51) which transmits heat generated by the worm wheel (24) to the housing (12).SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a speed reducer.

Background Art

[0002] There is an industrial robot with a joint part in industrial robots. By the way, a speed reducer is arranged in the joint part. However, due to the heat generated in the speed reducer, the rotating shaft in the speed reducer becomes high temperature, and there is a risk that the bearing of the rotating shaft is damaged. For this reason, Patent Document 1 discloses a technique for radiating the heat generated by the speed reducer by forming a plurality of heat dissipation holes for heat dissipation in a pulley fixed to the input shaft of the speed reducer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since the pulley used for heat dissipation in Patent Document 1 is a pulley in which a plurality of heat dissipation holes are provided in an existing pulley of the speed reducer, the heat transmitted to the pulley can only be dissipated from the heat dissipation holes, and the heat dissipation of the input shaft cannot be sufficiently performed. For this reason, there is a risk that the bearing of the input shaft or the like is affected by heat and damaged. Thus, the technique of Patent Document 1 cannot be said to have sufficient heat dissipation measures in the speed reducer.

[0005] One aspect of the present invention aims to realize a speed reducer in which heat is hardly accumulated in the rotating shaft and the bearing of the rotating shaft is hardly affected by heat by sufficiently taking heat dissipation measures in the speed reducer.

Means for Solving the Problems

[0006] To solve the above problems, a reduction gear according to one aspect of the present invention is a reduction gear that reduces and outputs the rotational speed of a motor, and includes a case, an input shaft, an intermediate shaft, and an output shaft rotatably supported in the case, a first wheel attached to the intermediate shaft and transmitting the rotation of the motor to the intermediate shaft via the input shaft, a second wheel attached to the intermediate shaft and transmitting the rotation of the intermediate shaft to the output shaft, and a first heat dissipation member provided on the side surface of the first wheel, integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case.

[0007] According to the above configuration, the heat generated in the first wheel is dissipated to the case from a first heat dissipation member, which is provided on the side of the first wheel, integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case. In this case, the distance from the first heat dissipation member to the case is shorter than the distance from the intermediate shaft to the case, so the thermal resistance between the first heat dissipation member and the case is lower than the thermal resistance between the intermediate shaft and the case. Therefore, if the thermal resistance between the first heat dissipation member and the case is lower, the heat from the first heat dissipation member is more easily transferred to the case. As a result, more heat from the first wheel is dissipated to the case via the first heat dissipation member than through the intermediate shaft, so heat from the first wheel is less likely to accumulate on the intermediate shaft. Therefore, the intermediate shaft can be prevented from becoming hot, and the bearings of the intermediate shaft are also less likely to become hot. In other words, heat is less likely to accumulate on the intermediate shaft, and the bearings of the intermediate shaft are less likely to be affected by heat. Thus, by implementing sufficient heat dissipation measures in the gearbox, it is possible to prevent the bearings of the intermediate shafts within the gearbox from failing in a short period of time.

[0008] The system may further include a second heat dissipation member provided on the side of the second wheel, integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case. With the above configuration, the heat generated in the second wheel is dissipated from the second heat dissipation member provided on the side of the second wheel, integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case, and transferred to the case. As a result, heat from the second wheel is less likely to accumulate on the intermediate shaft, thus preventing the intermediate shaft from becoming hot, and the bearings of the intermediate shaft are also less likely to become hot. In other words, heat is less likely to accumulate on the intermediate shaft, and the bearings of the intermediate shaft are less likely to be affected by heat. In this way, if sufficient heat dissipation measures are taken in the gearbox, it is possible to prevent the bearings of the intermediate shaft in the gearbox from being damaged in a short period of time due to high temperatures.

[0009] The gap between the first heat dissipation member and / or the second heat dissipation member and the case may be filled with a heat-transmitting medium. With the above configuration, heat can be dissipated from the first heat dissipation member to the case via the medium, thereby enhancing the heat dissipation effect.

[0010] The opposing surfaces of the first heat dissipation member and / or the second heat dissipation member and the case may have a labyrinth structure. With the above configuration, the area of ​​the opposing surfaces of the first heat dissipation member and / or the second heat dissipation member and the case becomes larger than when the opposing surfaces are flat, so the heat dissipation effect from the first heat dissipation member to the case can be further enhanced.

[0011] The aforementioned medium may be a medium with a higher thermal conductivity than air. With the above configuration, the heat dissipation effect of the first heat dissipation member can be further enhanced.

[0012] When the opposing surfaces of the first heat dissipation member and / or the second heat dissipation member and the case are in a labyrinth structure, the medium may be a medium with a higher thermal conductivity than air. With the above configuration, the heat dissipation effect of the first heat dissipation member and / or the second heat dissipation member can be further enhanced when the opposing surfaces of the first heat dissipation member and / or the second heat dissipation member and the case are in a labyrinth structure. [Effects of the Invention]

[0013] According to one aspect of the present invention, sufficient heat dissipation measures can be taken in the gearbox. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic front view of a gear device equipped with a reduction gear according to Embodiment 1 of the present invention. [Figure 2] This is a cross-sectional view taken along the line 2-2 in Figure 1. [Figure 3] This is a cross-sectional view taken along the line 3-3 in Figure 2. [Figure 4] Figure 2 is a magnified view of the main components of the gearbox shown. [Figure 5] This is a schematic cross-sectional view of a speed reducer according to Embodiment 2 of the present invention. [Figure 6] This is a schematic cross-sectional view of a speed reducer according to Embodiment 3 of the present invention. [Modes for carrying out the invention]

[0015] [Embodiment 1] One embodiment of the present invention will be described in detail below.

[0016] <Gear System> FIG. 1 is a schematic front view of a gear device according to the present embodiment. As shown in FIG. 1, the gear device 10 includes a motor M and a speed reducer 11 to which the motor M is connected. The speed reducer 11 includes a housing (case) 12. Inside the housing 12, an input shaft 14, an output shaft 16, and an intermediate shaft 18 are rotatably housed. Further, a worm gear 20 and a spur gear 30 are housed.

[0017] Since the input shaft 14 of the motor M is connected to the worm 22 of the worm gear 20, the torque from the motor M is transmitted to the worm 22, and then transmitted to a worm wheel (first wheel) 24 that meshes with the worm 22 via a meshing portion 26. The torque transmitted to the worm wheel 24 is transmitted to an input spur gear (second wheel) 32 provided on the same axis as the intermediate shaft 18 through the intermediate shaft 18 rotatably provided in the housing 12. Since the input spur gear 32 meshes with an output spur gear 34 provided on the output shaft 16 via a spur gear meshing portion 37, the torque transmitted to the input spur gear 32 is transmitted to the output shaft 16 through the output spur gear 34. A shaft or the like not shown is connected to the output shaft 16. In addition to the hollow one shown in the figure, the output shaft 16 may be a solid shaft.

[0018] <Reducer> FIG. 2 is a sectional view taken along the line 2-2 in the direction of the arrow of the gear device 10 shown in FIG. 1. FIG. 3 is a sectional view taken along the line 3-3 in the direction of the arrow of FIG. 2. FIG. 4 is an enlarged view of the main part of the speed reducer shown in FIG. 2.

[0019] As shown in Fig. 2, the speed reducer 11 includes an intermediate shaft 18, an output shaft 16, a worm wheel (first wheel) 24, an input parallel gear (second wheel) 32, an output parallel gear 34, a first heat dissipation collar (first heat dissipation member) 51, a second heat dissipation collar (second heat dissipation member) 52, a first bearing 61 and a second bearing 62 that rotatably support the intermediate shaft 18 within the housing 12, and a third bearing 63 and a fourth bearing 64 that rotatably support the output shaft 16 within the housing 12. Here, the worm wheel 24 and the input parallel gear 3 are attached to the intermediate shaft 18 and constitute a rotational transmission mechanism that transmits the rotation of the motor M (Fig. 1) to the intermediate shaft 18 via the input shaft 14 (Fig. 1) and transmits the rotation of the intermediate shaft 18 to the output shaft 16. Specifically, the worm wheel 24 is attached to the intermediate shaft 18 and is the first wheel that transmits the rotation of the motor M to the intermediate shaft 18 via the input shaft 14, and the input parallel gear 32 is attached to the intermediate shaft 18 coaxial with the worm wheel 24 and is the second wheel that transmits the rotation of the intermediate shaft 18 to the output shaft 16.

[0020] As shown in Fig. 2, sealing members 42 and 44 are disposed between the housing 12 and the output shaft 16. As a result, the interior of the housing 12 is sealed. On the inner surface of the housing 12, there are a worm wheel tooth surface facing surface 25 (see Fig. 1) that faces at least a part of the tooth surface of the worm wheel 24, a worm tooth surface facing surface 23 that faces at least a part of the tooth surface of the worm 22, a worm wheel one-side surface facing surface 27 that faces at least a part of one side surface of the worm wheel 24, a worm wheel other-side surface facing surface 28 that faces at least a part of the other side surface of the worm wheel 24, an input parallel gear tooth surface facing surface 36 that faces at least a part of the tooth surface of the input parallel gear 32, and an output parallel gear tooth surface facing surface 38 that faces at least a part of the tooth surface of the output parallel gear 34.

[0021] In the gear unit 10, grease 46 is filled between the meshing portion 26 of the worm 22 and the worm wheel 24, and between the tooth surface of the worm wheel 24 and the surface 25 facing the tooth surface of the worm wheel. Furthermore, grease 46 is also filled between one side of the worm wheel 24 and the surface 27 facing that side of the worm wheel. Here, "filled" means packed to the extent that it contacts both components, so that the grease 46 is packed to the extent that it contacts both the tooth surface of the worm wheel 24 and the surface 25 facing the tooth surface of the worm wheel, and both one side of the worm wheel 24 and the surface 27 facing that side of the worm wheel. The grease 46 used is a high-viscosity, non-flowing, hard grease that adheres to the worm 22, worm wheel 24, and the surface 25 facing the tooth surface of the worm wheel and does not flow off; in other words, it is a high-concentration grease. The grease 46, including the grease filled in other parts described later, is filled in a continuous manner with respect to each other.

[0022] In this way, by filling the meshing portion 26 of the worm gear 20, the space between the tooth surface of the worm wheel 24 and the opposing surface 25 of the worm wheel tooth surface, and the space between one side of the worm wheel 24 and the opposing surface 27 of the worm wheel side, with grease 46, even when the worm gear 20 rotates at high speed, the grease 46 filled in the meshing portion 26 of the worm gear 20 is suppressed by the grease 46 filled between one side of the worm wheel 24 and the opposing surface 27 of the worm wheel side, thus maintaining the lubrication of the worm gear 20. Therefore, it is not necessary to fill the entire inside of the housing 12 with grease 46 to lubricate the worm gear 20, making it easier to prevent oil leakage, and eliminating the need for greases of different properties or parts for circulating grease. Thus, a simple structure can be achieved.

[0023] Furthermore, the heat generated by the meshing of the worm 22 and the worm wheel 24 is easily transferred to the housing 12 through the grease 46 filled between one side of the worm wheel 24 and the opposing surface 27 of one side of the worm wheel, and this heat can be dissipated from the housing 12, thus suppressing the heat generation of the worm gear 20. This is because the thermal conductivity of the grease 46 is greater than that of air, making it easier for heat to be transferred to the housing 12.

[0024] Furthermore, grease 46 may be further filled between the tooth surface of the worm 22 and the surface 23 opposite the worm tooth surface. This facilitates the supply of grease 46 to the meshing portion 26 of the worm 22 and the worm wheel 24, and promotes the transfer of heat from the worm 22 to the housing 12. On the other hand, by filling grease 46 between the other side of the worm wheel 24 and the surface 28 of the housing 12 opposite the other side of the worm wheel, it is possible to further prevent the scattering of grease filled in the meshing portion 26 of the worm gear 20, and further promote the transfer of heat from the worm wheel 24 to the housing 12, thereby further suppressing the heat generation of the worm gear 20.

[0025] In the case of a multi-stage gear system, such as gear system 10, which includes a worm gear 20 and a parallel gear 30, filling the parallel gear meshing portion 37 of the input parallel gear 32 and the output parallel gear 34, and the space between the input parallel gear 32 and the output parallel gear 34 facing the worm wheel 24 with grease 46, allows for lubrication of the worm gear 20 and the parallel gear 30 while suppressing oil leakage.

[0026] Furthermore, by filling the space between the tooth surface of the input parallel gear 32 and the opposing surface 36 of the housing 12, it is possible to prevent grease from scattering due to the rotation of the input parallel gear 32. Similarly, by filling the space between the tooth surface of the output parallel gear 34 and the opposing surface 38 of the housing 12, it is possible to prevent grease from scattering due to the rotation of the output parallel gear 34 and maintain the lubrication of the parallel gear 30.

[0027] Oil may be used instead of grease 46 to lubricate the rotation of the worm gear 20. In this embodiment, an example using high-concentration grease 46 will be described.

[0028] As shown in Figure 3, the reduction gear 11 transmits the rotation of the motor M to the worm wheel 24 via the worm gear 20, and further reduces the speed when transmitting it from the intermediate shaft 18 to the output shaft 16. When the rotational speed of the motor M is reduced in this way, heat is generated by the meshing of the worm 22 and the worm wheel 24. Here, the worm wheel 24 is the source of the heat. Heat is also generated by the meshing of the input parallel gear 32 and the output parallel gear 34. In this case, as with the worm wheel 24, the input parallel gear 32 is also a source of heat. Therefore, it is necessary to prevent the heat generated in the worm wheel 24 and the input parallel gear 32 from being transmitted to the intermediate shaft 18 as much as possible. In other words, if heat accumulates in the intermediate shaft 18, the intermediate shaft 18 will become hot. As a result, the bearings of the intermediate shaft 18 will also become hot, and the bearings that become hot will be damaged in a short period of time. For this reason, it is necessary to prevent the intermediate shaft 18 from becoming hot.

[0029] As described above, the grease 46 filled in the housing 12 allows heat generated by the worm wheel 24 and the input parallel gear 32 to be transferred to the housing 12, thereby suppressing to some extent the intermediate shaft 18 from being heated to a high temperature. However, in order to further improve heat dissipation, as described above, the first heat dissipation collar 51 fixed to the side of the worm wheel 24 dissipates the heat generated by the worm wheel 24 to the housing 12, and the second heat dissipation collar 52 fixed to the side of the input parallel gear 32 dissipates the heat generated by the input parallel gear 32 to the housing 12.

[0030] The first heat dissipation collar 51 is formed from a material with high thermal conductivity (e.g., aluminum) and has a roughly donut shape centered on the intermediate shaft 18, and is fixed to the worm wheel 24. In other words, the first heat dissipation collar 51 is fixed to the side surface of the worm wheel 24 and interposed between the intermediate shaft 18 and the opposing surface 12a of the housing 12. Therefore, the outer circumference of the first heat dissipation collar 51 is close to the opposing surface 12a which is integrally provided on the housing 12. In this way, the proximity of the first heat dissipation collar 51 to the housing 12 reduces the thermal resistance between the first heat dissipation collar 51 and the housing 12, making it easier to dissipate heat from the first heat dissipation collar 51 to the housing 12. Similarly to the first heat dissipation collar 51, the second heat dissipation collar 52 is formed from a material with high thermal conductivity (e.g., aluminum) and has a roughly donut shape centered on the intermediate shaft 18, and is fixed to the input parallel gear 32. In other words, the second heat dissipation collar 52 is fixed to the side of the input parallel gear 32 and interposed between the intermediate shaft 18 and the opposing surface 12a of the housing 12. Therefore, the outer circumference of the second heat dissipation collar 52 is in close proximity to the opposing surface 12a which is integrally provided on the housing 12. In this way, the proximity of the second heat dissipation collar 52 to the housing 12 reduces the thermal resistance between the second heat dissipation collar 52 and the housing 12, making it easier to dissipate heat from the second heat dissipation collar 52 to the housing 12. The housing 12 then further dissipates the heat dissipated from the first heat dissipation collar 51 and the second heat dissipation collar 52 to the outside.

[0031] The first heat dissipation collar 51 will be described in more detail. As shown in Figure 4, the bottom surface 51a of the first heat dissipation collar 51 is fixed on the worm wheel 24, the outer peripheral surface 51b is positioned close to the opposing surface 12a of the housing 12 at a predetermined distance d, the top surface 51c is formed so as not to contact the first bearing 61, and the inner peripheral surface 51d is provided in contact with or fixed to the outer peripheral surface of the intermediate shaft 18. Therefore, the first heat dissipation collar 51 rotates together with the worm wheel 24, but the outer peripheral surface 51b and the top surface 51c do not contact any of the components.

[0032] It is preferable to make the distance d (gap) between the outer circumferential surface 51b of the first heat dissipation collar 51 and the opposing surface 12a of the housing 12 as close as possible. In this embodiment, the distance d is 1 mm. However, if the distance d between the outer circumferential surface 51b of the first heat dissipation collar 51 and the opposing surface 12a of the housing 12 is too close, the shear resistance of the grease 46 filled in the housing 12 will increase, so it is necessary to leave a certain distance between the outer circumferential surface 51b of the first heat dissipation collar 51 and the opposing surface 12a of the housing 12. It is preferable to set the distance d between the outer circumferential surface 51b of the first heat dissipation collar 51 and the opposing surface 12a of the housing 12 taking these problems into consideration.

[0033] Furthermore, the gaps between the first heat dissipation collar 51 and the second heat dissipation collar 52 and the housing 12 are filled with a high-concentration grease 46, which is a medium with a higher thermal conductivity (lower thermal resistance) than air. In this case, even if the gaps are somewhat wide, the heat dissipation effect from the first heat dissipation collar 51 and the second heat dissipation collar 52 to the housing 12 will not be reduced by the medium (grease 46) filling the gaps.

[0034] Furthermore, it is preferable that the first heat dissipation collar 51 has a high height (distance from the bottom surface 51a to the top surface 51c). This increases the area S of the surface of the outer peripheral surface 51b of the first heat dissipation collar 51 that faces the opposing surface 12a of the housing 12, thereby reducing the thermal resistance between the first heat dissipation collar 51 and the housing 12 and improving heat dissipation efficiency. In this case, it is preferable that the area S be as large as possible. In other words, it is preferable that the outer peripheral surface 51b of the first heat dissipation collar 51 be as wide as possible. However, if the area S of the outer peripheral surface 51b of the first heat dissipation collar 51 is too large, the shear resistance of the grease 46 charged in the housing 12 will increase, so the area S of the outer peripheral surface 51b of the first heat dissipation collar 51 needs to be of a certain size. It is preferable to set the area S of the outer peripheral surface 51b of the first heat dissipation collar 51 taking these issues into consideration.

[0035] The second heat dissipation collar 52 will be described in more detail. As shown in Figure 2, the bottom surface of the second heat dissipation collar 52 is fixed to the input parallel gear 32, the outer surface is positioned close to the opposing surface 12a of the housing 12 at a predetermined distance d, the top surface is formed so as not to contact the second bearing 62, and the inner surface is provided in contact with or fixed to the outer surface of the intermediate shaft 18. Therefore, the second heat dissipation collar 52 rotates together with the input parallel gear 32, but the outer surface and top surface c do not come into contact with any of the components.

[0036] It is preferable to make the distance d (gap) between the outer surface of the second heat dissipation collar 52 and the opposing surface 12a of the housing 12 as close as possible. In this embodiment, the distance d is 1 mm. However, if the distance d between the outer surface of the second heat dissipation collar 52 and the opposing surface 12a of the housing 12 is too close, the shear resistance of the grease 46 filled in the housing 12 will increase, so it is necessary to leave a certain distance between the outer surface of the second heat dissipation collar 52 and the opposing surface 12a of the housing 12. It is preferable to set the distance d between the outer surface of the second heat dissipation collar 52 and the opposing surface 12a of the housing 12 taking these problems into consideration.

[0037] Furthermore, it is preferable that the second heat dissipation collar 52 has a high height (distance from the bottom surface to the top surface). This increases the area S of the outer surface of the second heat dissipation collar 52 that faces the opposing surface 12a of the housing 12, thereby reducing the thermal resistance between the second heat dissipation collar 52 and the housing 12 and improving heat dissipation efficiency. In this case, it is preferable that the area S be as large as possible. In other words, it is preferable that the outer surface of the second heat dissipation collar 52 be as wide as possible. However, if the area S of the outer surface of the second heat dissipation collar 52 is too large, the shear resistance of the grease 46 charged in the housing 12 will increase, so the area S of the outer surface of the second heat dissipation collar 52 needs to be of a certain size. It is preferable to set the area S of the outer surface of the second heat dissipation collar 52 taking these issues into consideration.

[0038] In the following embodiments 2 and 3, a heat dissipation member configuration other than the first heat dissipation collar 51 and the second heat dissipation collar 52 described in embodiment 1 will be described.

[0039] [Embodiment 2] Other embodiments of the present invention will be described below. For the sake of clarity, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0040] Figure 5 is a schematic cross-sectional view of the gearbox 111 according to this embodiment. As shown in Figure 5, the gearbox 111 has the same configuration as the gearbox 11 of Embodiment 1, except that it is equipped with a first heat dissipation collar 151 and a second heat dissipation collar 152 instead of the first heat dissipation collar 51 and the second heat dissipation collar 52 of the gearbox 11 of Embodiment 1, and the shape of the opposing surfaces of the first heat dissipation collar 151 and the second heat dissipation collar 152 in the housing 12. The shapes of the first heat dissipation collar 151 and the second heat dissipation collar 152 and the opposing surfaces of the housing 12 will be described below.

[0041] The first heat dissipation collar 151, like the first heat dissipation collar 51 in Embodiment 1, is formed of a material with high thermal conductivity (e.g., aluminum) with a roughly donut shape centered on the intermediate shaft 18, and is in contact with the worm wheel 24. Specifically, the bottom surface 151a of the first heat dissipation collar 151 is provided on the worm wheel 24, the top surface 151c is formed in an uneven shape so as not to contact the first bearing 61, and the inner circumferential surface 151d is provided in contact with or fixed to the outer circumferential surface of the intermediate shaft 18.

[0042] Here, the irregularities on the upper surface 151c of the first heat dissipation collar 151 are formed to interlock with the irregularities 27a formed on the opposing surface 27 of the worm wheel side of the housing 12. In other words, the irregularities on the upper surface 151c of the first heat dissipation collar 151 and the irregularities 27a formed on the opposing surface 27 of the worm wheel side of the housing 12 interlock with each other on their respective opposing surfaces, forming a so-called labyrinth structure. However, it is preferable to make the gap between the irregularities on the upper surface 151c of the first heat dissipation collar 151 and the irregularities 27a formed on the opposing surface 27 of the worm wheel side of the housing 12 as narrow as possible, similar to the distance d (gap) between the outer peripheral surface 51b of the first heat dissipation collar 51 and the opposing surface 12a of the housing 12 in the embodiment 1.

[0043] Because the surface between the unevenness of the upper surface 151c of the first heat dissipation collar 151 and the unevenness 27a formed on the opposing surface 27 of one side of the worm wheel of the housing 12 forms a labyrinth structure, the area of ​​the opposing surfaces is larger compared to when the opposing surfaces are flat. As a result, the thermal resistance between the first heat dissipation collar 151 and the housing 12 is reduced, and the heat dissipation effect from the first heat dissipation collar 151 to the housing 12 can be improved.

[0044] The second heat dissipation collar 152, like the second heat dissipation collar 52 in Embodiment 1, is formed of a material with high thermal conductivity (e.g., aluminum) with a roughly donut shape centered on the intermediate shaft 18 and is fixed to the input parallel gear 32. Specifically, the bottom surface 152a of the second heat dissipation collar 152 is in contact with the side surface of the input parallel gear 32, the top surface 152c is formed in an uneven shape so as not to contact the second bearing 62, and the inner circumferential surface 152d is provided in contact with or fixed to the outer circumferential surface of the intermediate shaft 18.

[0045] Here, the irregularities on the upper surface 152c of the second heat dissipation collar 152 are formed to interlock with the irregularities 28a formed on the opposing side surface 28 of the housing 12 that faces the worm wheel. In other words, the irregularities on the upper surface 152c of the second heat dissipation collar 152 and the irregularities 28a formed on the opposing side surface 28 of the housing 12 that faces the worm wheel interlock with each other on their respective opposing surfaces, forming a so-called labyrinth structure. However, it is preferable that the gap (part indicated by reference numeral 151b) between the irregularities on the upper surface 152c of the second heat dissipation collar 152 and the irregularities 28a formed on the opposing side surface 28 of the housing 12 that faces the worm wheel should be as narrow as possible, similar to the distance d (gap) between the outer peripheral surface 51b of the first heat dissipation collar 51 and the opposing surface 12a of the housing 12 in the embodiment 1.

[0046] Because the surface of the second heat dissipation collar 152 has a labyrinth structure, the area of ​​the opposing surfaces is larger compared to when the opposing surfaces are flat. As a result, the thermal resistance of the second heat dissipation collar 152 is reduced, and the heat dissipation effect from the second heat dissipation collar 152 to the housing 12 is enhanced.

[0047] As described above, with the reduction gear 111 configured above, the opposing surfaces of the first heat dissipation collar 151 and the housing 12, and the opposing surfaces of the second heat dissipation collar 152 and the housing 12, are in a labyrinth structure, so the area of ​​the opposing surfaces can be increased compared to the case where the opposing surfaces are flat. This makes it possible to increase the heat dissipation efficiency from the first heat dissipation collar 151 and the second heat dissipation collar 152 to the housing 12. Moreover, if the heat dissipation efficiency is the same (the area of ​​the opposing surfaces is the same), the height of the first heat dissipation collar 151 (height from the worm wheel 24 to the first bearing 61) can be lower than that of the first heat dissipation collar 51. Similarly, if the heat dissipation efficiency is the same (the area of ​​the opposing surfaces is the same), the height of the second heat dissipation collar 152 (height from the input parallel gear 32 to the second bearing 62) can be lower than that of the second heat dissipation collar 52. Therefore, it is possible to miniaturize the heat dissipation members and the reduction gear.

[0048] [Embodiment 3] Other embodiments of the present invention will be described below. For the sake of clarity, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0049] Figure 6 is a schematic cross-sectional view of the gearbox 211 according to this embodiment. As shown in Figure 6, the gearbox 211 has the same configuration as the gearbox 11 of Embodiment 1, except that it is equipped with a first heat dissipation collar 251 and a second heat dissipation collar 252 instead of the first heat dissipation collar 51 and the second heat dissipation collar 52 of the gearbox 11 of Embodiment 1. The shapes of the first heat dissipation collar 251 and the second heat dissipation collar 252 will be described below.

[0050] The first heat dissipation collar 251 is formed integrally with the first heat dissipation collar 51 of Embodiment 1 and the worm wheel 24. In other words, the first heat dissipation collar 251 includes a wheel portion 251a which is a heat source and a heat dissipation portion 251b which is a heat dissipation member. The wheel portion 251a has the same function as the worm wheel 24 of Embodiment 1, and the heat dissipation portion 251b has the same function as the first heat dissipation collar 51 of Embodiment 1. The upper surface 251c of the heat dissipation portion 251b is formed so as not to contact the first bearing 61, and the inner circumferential surface 251d of the wheel portion 251a is provided in contact with or fixed to the outer circumferential surface of the intermediate shaft 18.

[0051] Here, a gap is formed between the outer circumferential surface of the heat dissipation portion 251b of the first heat dissipation collar 251 and the opposing housing 12. It is preferable to make this gap as narrow as possible, similar to the distance d (gap) between the outer circumferential surface 51b of the first heat dissipation collar 51 and the opposing surface 12a of the housing 12 in the first embodiment.

[0052] The second heat dissipation collar 252 is formed by integrally integrating the second heat dissipation collar 52 of Embodiment 1 with the intermediate shaft 18. Therefore, the second heat dissipation collar 252 is formed in a substantially flange-like shape centered on the intermediate shaft 18.

[0053] The second heat dissipation collar 252 is formed such that its upper surface 252a contacts the side surface of the input parallel gear 32, its outer peripheral surface 252b faces the other side surface 28 of the housing 12 facing the worm wheel at a predetermined distance, and its bottom surface 252c does not contact the second bearing 62.

[0054] Here, it is preferable that the gap formed between the outer peripheral surface 252b of the second heat dissipation collar 252 and the opposing side surface 28 of the housing 12 facing the worm wheel is as narrow as possible, similar to the distance d (gap) between the heat dissipation portion 251b of the first heat dissipation collar 251 and the opposing surface of the housing 12.

[0055] In the speed reducers 11, 111, and 211 of the embodiments 1 to 3 described above, in order to improve heat dissipation efficiency, it is preferable that the heat dissipation members, cases, and grease fillings included in the heat dissipation bypass path for dissipating heat generated by the heat source are made of materials with high thermal conductivity. Here, it is preferable that the heat dissipation members and cases (housings) are made of materials with a thermal conductivity of, for example, aluminum die-cast (thermal conductivity of about 96 W / mK) or higher. Furthermore, it is preferable that the filling medium (grease, etc.) has a thermal conductivity of about 0.15 W / mK or higher.

[0056] Furthermore, although the speed reducers 11, 111, and 211 in embodiments 1 to 3 were described using two-stage speed reducers as examples, the present invention can also be applied to heat dissipation measures in the intermediate shaft of speed reducers that reduce speed in three or more stages.

[0057] Furthermore, although the examples of the speed reducers 11, 111, and 211 of embodiments 1 to 3 described above show the heat dissipation member in contact with or integrated with the wheel, the heat dissipation member does not necessarily have to be in contact with the wheel. If the heat dissipation member is in contact with the intermediate shaft, the heat from the wheel will be transferred from the intermediate shaft to the heat dissipation member. The heat transferred to the heat dissipation member will then be transferred to the case and dissipated.

[0058] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0059] 10 Gear system 11 Reducer 12 Housing (Case) 14 Input axes 16 Output shaft 18 Intermediate axis 20 Worm Gear 22 Warm 23 Worm tooth surface opposing surface 24 Worm wheel (first wheel) 25 Worm wheel tooth surfaces facing each other 27 Worm wheel, one side, opposing surfaces 27a Unevenness 28 Worm wheel other side opposing surface 28a unevenness 30 parallel gears 32 Input parallel gear (second wheel) 34 Output parallel gears 36 Input parallel gear tooth surfaces facing each other 38 Output parallel gear tooth surfaces facing each other 42,44 Sealing member 46 Grease 51. First heat dissipation collar (first heat dissipation component) 51a Bottom 51b Outer surface 51c top surface 51d Inner surface 52. Second heat dissipation collar (second heat dissipation component) 61 First bearing 62 Second bearing 63 Third bearing 64. Fourth bearing 111 Reducer 151 First heat dissipation collar (first heat dissipation component) 151a Bottom 151c top surface 151d Inner surface 152 Second heat dissipation collar (second heat dissipation component) 152a Bottom 152c top surface 152d Inner surface 211 Reducer 251 First heat dissipation collar (first heat dissipation component) 251a Wheel section 251b Heat dissipation part 251c top surface 251d Inner surface 252 Second heat dissipation collar (second heat dissipation component) 252a top surface 252b Outer surface 252c bottom M Motor S area d Distance (gap)

Claims

1. A reduction gear that reduces the rotational speed of a motor and outputs the result, The case and, The aforementioned case includes an input shaft, an intermediate shaft, and an output shaft that are rotatably supported, A first wheel is attached to the aforementioned intermediate shaft and transmits the rotation of the motor to the intermediate shaft via the input shaft, A second wheel is attached to the intermediate shaft and transmits the rotation of the intermediate shaft to the output shaft, The first heat dissipation member is provided on the side surface of the first wheel, or integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case, The first heat dissipation member has a donut shape centered on the intermediate axis, is interposed between the intermediate axis and the opposing surface located on the outer circumference side of the intermediate axis in the case, and the outer circumference of the first heat dissipation member is located in close proximity to the opposing surface. A gearbox in which at least the gap between the first heat dissipation member and the case is filled with a heat transfer medium.

2. The present invention further includes a second heat dissipation member provided on the side surface of the second wheel, integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case, The second heat dissipation member has a donut shape centered on the intermediate axis, is interposed between the intermediate axis and the opposing surface located on the outer circumference side of the intermediate axis in the case, and the outer circumference of the second heat dissipation member is located in close proximity to the opposing surface. The gearbox according to claim 1, wherein at least the gap between the second heat dissipation member and the case is filled with a heat transfer medium.

3. A reduction gear that reduces the rotational speed of a motor and outputs the result, The case and, The aforementioned case includes an input shaft, an intermediate shaft, and an output shaft that are rotatably supported, A first wheel is attached to the aforementioned intermediate shaft and transmits the rotation of the motor to the intermediate shaft via the input shaft, A second wheel is attached to the intermediate shaft and transmits the rotation of the intermediate shaft to the output shaft, The first heat dissipation member is provided on the side surface of the first wheel, or integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case, At least the gap between the first heat dissipation member and the case is filled with a heat transfer medium. A gearbox in which the opposing surfaces of the first heat dissipation member and the case are in a labyrinth structure.

4. A reduction gear that reduces the rotational speed of a motor and outputs the result, The case and, The aforementioned case includes an input shaft, an intermediate shaft, and an output shaft that are rotatably supported, A first wheel is attached to the aforementioned intermediate shaft and transmits the rotation of the motor to the intermediate shaft via the input shaft, A second wheel is attached to the intermediate shaft and transmits the rotation of the intermediate shaft to the output shaft, The first heat dissipation member is provided on the side surface of the first wheel, or integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case, At least the gap between the first heat dissipation member and the case is filled with a heat transfer medium. The present invention further includes a second heat dissipation member provided on the side surface of the second wheel, integrally formed with it, or provided on the intermediate shaft and interposed between the intermediate shaft and the case, At least the gap between the second heat dissipation member and the case is filled with a heat transfer medium. A gearbox in which the opposing surfaces of the first heat dissipation member and the case, and the opposing surfaces of the second heat dissipation member and the case, are in a labyrinth structure.

5. The gearbox according to any one of claims 1 to 4, wherein the medium is a medium with a higher thermal conductivity than air.

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