Device for speed reduction

Abstract

A speed reduction device (10, 110) comprising: a housing (30) accommodating a speed reduction mechanism, an input shaft comprising a projecting section (12) extending outward from the housing (30), a fan (40) arranged on the projecting section (12) of the input shaft, and a fan cover (50, 150) covering the fan (40), wherein the fan cover (50, 150) comprises a cylindrical section (54, 156) and a trumpet-shaped section (52, 152) connected to the cylindrical section (54, 156) and comprising an inner surface inclined such that it faces away from the input shaft toward a load side, and wherein a flow-aligning rib (62, 64, 162, 164) is provided on an inner surface of the trumpet-shaped section, and wherein the cylindrical section (54, 156) is provided on the load side of the trumpet-shaped section,wherein the flow-aligning rib (62, 64, 162, 164) provided on the inner surface of the trumpet-shaped section is spaced apart from the housing (30).

Description

Background of the invention Field of invention Certain embodiments of the invention relate to a device for reducing speed. Description of the state of the art Components belonging to a specific assembly, such as gears inside a speed reduction device, rotate at high speeds. In particular, because the rotational speed of an input shaft is higher than that of an output shaft, heat generation on the input shaft becomes a problem. If the temperature of the speed reduction device becomes high, a problem arises in that bearings can be damaged prematurely due to the aging of a seal or oil, or due to a reduction in the oil film. For this reason, a design is known in which a cooling fan is provided on the input shaft of the speed reduction device. The unexamined Japanese patent application publication JP 2013-204 814 A discloses a structure of a velocity reduction device comprising a housing which includes a velocity reduction mechanism, an input shaft with a projecting section extending outwards from the housing, a fan arranged on the projecting section of the input shaft and a fan hood covering the fan, wherein the fan hood includes an extended section covering a lateral surface of the housing and wherein flow-aligning ribs are arranged on the inside of the extended section. In the unexamined Japanese patent application publication JP 2013-204 814 A, the effect for aligning the air drawn into the fan hood by the fan is insufficient, and it cannot necessarily be assumed that a sufficient cooling effect is achieved. A transmission cooling device is known from JP H05-137 401 A, which prevents abrasion and damage to connecting shafts and gears. Furthermore, a gearbox with a shaft is known from DE 10 2012 025 596 A1, wherein a fan wheel is rotationally fixed to the shaft. A cooling device for a gearbox is also known from GB 2 282 206 A. Summary of the invention The present invention is made in consideration of this problem, and an objective of the present invention is to provide a technology for effectively cooling an input shaft side of a velocity reduction device, comprising a fan on the input shaft side and a fan hood covering the fan. This problem is solved by devices for speed reduction according to the independent patent claims. According to embodiments of the present invention, a speed reduction device is provided comprising a housing accommodating a speed reduction mechanism, an input shaft comprising a projecting section extending outwards from the housing, a fan arranged on the projecting section of the input shaft, and a fan hood covering the fan, wherein the fan hood comprises a cylindrical section and a trumpet-shaped section connected to the cylindrical section and comprising an inner surface inclined such that it faces away from the input shaft towards a load side, and wherein a flow-aligning rib is provided on an inner surface of the trumpet-shaped section. According to one embodiment of the present invention, the cylindrical section is provided on the load side of the trumpet-shaped section, wherein the flow-aligning rib provided on the inner surface of the trumpet-shaped section is spaced apart from the housing. According to a further embodiment of the present invention, the speed reduction device is used in a state in which a lower surface of the housing is mounted on a base, wherein the trumpet-shaped section comprises a section with increasing diameter having an inner surface inclined such that it faces away from the input shaft towards the load side, and a flat section having an inner surface parallel to the input shaft, wherein the trumpet-shaped section has a pair of the sections with increasing diameter, which are arranged accordingly on an upper surface side and a flat surface side, respectively.are arranged on a lower surface side of the housing, wherein the trumpet-shaped section has a pair of flat sections, each of which is designed to connect the increasing diameter section on the upper surface side to the increasing diameter section on the lower surface side, and wherein the flow-aligning rib is arranged on an inner surface of the increasing diameter section on the upper surface side and the pair of flat sections, and the flow-aligning rib is not arranged on an inner surface of the increasing diameter section on the lower surface side. According to a further embodiment of the present invention, the trumpet-shaped section comprises a section with increasing diameter having an inner surface inclined towards the load side away from the input shaft, and a flat section having an inner surface parallel to the input shaft, wherein a second flow-aligning rib is arranged on an inner surface of the cylindrical section connected to the flat section, and simultaneously the flow-aligning rib is arranged on an inner surface of the section with increasing diameter. According to a further embodiment of the present invention, the cylindrical section comprises a first cylindrical section connected to a non-load side of the trumpet-shaped section and a second cylindrical section connected to a load side of the trumpet-shaped section. According to a further embodiment, the trumpet-shaped section comprises a section with increasing diameter having an inner surface inclined towards the load side away from the input shaft, and a flat section having an inner surface parallel to the input shaft, wherein the section with increasing diameter comprises a central section with increasing diameter and left and right sections with increasing diameter arranged accordingly on the left and right sides of the central section with increasing diameter, respectively, and the flow-aligning rib is arranged on an inner surface of the central section with increasing diameter. According to the embodiments, the flow of air drawn into the fan housing by the fan is aligned by the flow-directing rib arranged on the inner surface of the trumpet-shaped section, and air flowing out of the fan housing flows along the perimeter of an outer surface of the housing. As a result, cooling effects are improved. A random combination of assembly components, or the replacement of the assembly components or the assembly of the embodiments of the present invention in a method, a device or a system acts as an embodiment of the present invention. According to the embodiments of the present invention, it is possible to effectively cool the input shaft side of the speed reduction device, which comprises the fan on the input shaft side and the fan hood covering the fan. Brief description of the drawings - Fig. 1 is a perspective view from above of a speed reduction device corresponding to one embodiment of the present invention. - Fig. 2 is a perspective view from below of the speed reduction device from Fig. 1. - Fig. 3 is a top view showing an input shaft side of the speed reduction device from Fig. 1. - Fig. 4 is a front view showing the input shaft side of the speed reduction device from Fig. 1. - Fig. 5 is a perspective view from above of a speed reduction device corresponding to another embodiment of the present invention. - Fig. 6 is a perspective view from below of the speed reduction device corresponding to another embodiment of the present invention from Fig. 5.Figure 7 is a top view showing the input shaft side of the speed reduction device from Figure 5. Figure 8 is a front view showing the input shaft side of the speed reduction device from Figure 5. Detailed description of the invention Fig. 1 is a perspective view of a speed reduction device 10 corresponding to an embodiment of the present invention, viewed diagonally from an upper left side. Fig. 2 is a perspective view of the speed reduction device 10, viewed diagonally from a lower left side. The speed reduction device 10 comprises a speed reduction mechanism (not shown) consisting of a three-stage reduction gear with perpendicular axes using a bevel gear. The speed reduction mechanism includes an input shaft (only a projecting section 12 is shown), a first intermediate shaft 32 perpendicular to the input shaft, a second intermediate shaft 36 meshing with the first intermediate shaft 32 by means of a helical gear, and an output shaft 38 meshing with the second intermediate shaft 36 by means of a helical gear. The input shaft, the first intermediate shaft 32, and the second intermediate shaft 36 of the speed reduction mechanism are housed within a casing 30. The output shaft 38 is also housed within the casing 30, and a section of the output shaft 38 projects from the casing. The input shaft, the first intermediate shaft 32, the second intermediate shaft 36, and the output shaft 38 are each supported within the casing 30 by bearings (not shown). An internal space, defined by the casing 30, is filled with oil as a lubricant. The speed reduction device 10 is used in a configuration where the lower surface of the casing 30 is mounted on a base or similar surface. A well-known speed reduction mechanism is used as the mechanism for reducing the speed inside such a speed reduction device, and therefore a detailed description thereof is omitted in this application. The projecting section 12 is located at the end of the input shaft and extends outwards from the housing 30. The projecting section 12 of the input shaft is connected to an output shaft of a (not shown) drive motor via a key, coupling, or similar device. A projecting section 38a, extending from the housing 30, is located at the end of the output shaft 38. An input shaft of a (not shown) driven machine is connected to the projecting section 38a via a key, coupling, or similar device. In the following description, a non-load side refers to a side on which the input shaft of the speed reduction device 10 is located, and a load side refers to a side on which the output shaft 38 is located. A cooling fan 40 is attached to the projecting section 12 of the input shaft. Preferably, a radial fan is used as fan 40 to direct the intake air radially outwards, regardless of the direction in which the input shaft rotates. In a case where the input shaft rotates in only one direction, an axial fan can be used as fan 40. A fan shroud 50 is attached to an end section of the non-load side of the housing 30 and covers the fan 40. The fan shroud is generally designed in a substantially bowl-like shape. The fan housing 50 comprises a cylindrical section 54 with an inner surface extending parallel to the input shaft, and a trumpet-shaped section 52 connected to the cylindrical section 54, which has an inner surface inclined towards the load side, away from the input shaft. In this embodiment, the cylindrical section 54 is formed from eight surfaces, and both the inner and outer surfaces of the cylindrical section 54 are parallel to the input shaft. An inclined section 51, inclined towards the projecting section 12 of the input shaft, is connected to the non-load side of the trumpet-shaped section 52. An opening section 53 on the non-load side of the fan housing 50 is formed on the side of the inclined section 51 with a smaller diameter. A load-side opening section 58 is formed on the load side of the fan housing 50.In this embodiment, a gap of approximately 20 mm to approximately 50 mm is formed between the load-side opening section 58 and an outer surface of the housing 30. When the fan 40 is rotated, air is drawn into the fan housing 50 through the opening section 53 on the non-load side, and air streams are blown from the load-side opening section 58 onto the load side of the device 10 for velocity reduction. More precisely, the trumpet-shaped section 52 of the fan housing 50 is designed to include a section 52a with an increasing diameter, having an inner surface inclined towards the load side away from the input shaft, and a flat section 52b with an inner surface parallel to the input shaft. A pair of the sections 52a with increasing diameter is arranged on the upper and lower surface sides of the housing 30, respectively. A pair of left and right flat sections 52b are present to connect the sections 52a with increasing diameter on the upper surface side to the sections 52a with increasing diameter on the lower surface side. The flat section 52b forms a continuous surface that is contiguous with a side surface of the cylindrical section 54.As a result, in such a structure the cross-section of the trumpet-shaped section 52, which is perpendicular to the axis, has an octagonal shape. It is possible to reduce the time that the airflows generated by the fan 40 spend at the corners of the fan hood and to blow parallel airflows from the load-side opening section 58 of the fan hood 50 along the outer surface of the housing 30 by forming the trumpet-shaped section 52 in an octagonal shape approximating a circle, compared to a case in which the trumpet-shaped section has a rectangular cross-section. A cutout 70 can be formed in an upper surface of the cylindrical section 54, so that a (not shown) suspension device attached to the housing 30 is accessible through the cutout 70 if the device 10 is suspended for velocity reduction. Provided that a sufficient axial length of the cylindrical section 54 is ensured, the formation of the cutout 70 has almost no effect on the formation of parallel airflows on the upper surface. Figures 3 and 4 are a top view and a front view, respectively, showing the non-load side of the speed reduction device 10. In Figures 3 and 4, a structure concealed by the fan housing 50 is indicated by the dashed line. As shown in the drawings, the increasing-diameter section 52a of the trumpet-shaped section 52 comprises a central increasing-diameter section 52a1 and left and right increasing-diameter sections 52a2, arranged accordingly on the left and right sides of the central increasing-diameter section 52a1. A flow-aligning rib 62 is arranged on an inner surface of the central increasing-diameter section 52a1 on its upper surface. In this embodiment, two flow-aligning ribs 62 are provided, but other numbers of flow-aligning ribs 62 may be provided. No flow-aligning ribs are provided on an inner surface of each of the left and right increasing-diameter sections 52a2 on their upper surface.No flow-aligning ribs are provided on the inner surface of any of the middle sections 52a1 with increasing diameter or of the left and right sections 52a2 with increasing diameter on the lower surface side. The stream of air currents generated by the fan 40 is aligned, and parallel air currents are generated along the outer surface of the housing 30 by the flow-aligning ribs on the inner surface of the fan hood 50. A flow-aligning rib 64 (second flow-aligning rib) can also be provided on an inner surface of the cylindrical section 54 connected to the flat section 52b of the trumpet-shaped section 52, together with the provision of flow-aligning ribs 62 on the inner surface of the section 52a with increasing diameter of the trumpet-shaped section 52. In this embodiment, three flow-aligning ribs 64 are provided on each of the left and right lateral surfaces (surfaces that are each connected to the flat sections 52b of the trumpet-shaped section 52) of the cylindrical section 54; however, a different number of flow-aligning ribs 64 can be provided. As shown in Fig.As shown in Figure 4, the flow-guiding ribs 62 of the trumpet-shaped section 52 and the flow-guiding ribs 64 of the cylindrical section 54 are preferably arranged such that at least sections of the flow-guiding ribs 62 and the flow-guiding ribs 64 overlap each other in a circumferential direction. That is, the flow-guiding ribs 64 are preferably arranged over both the cylindrical section 54 and the flat section 52b of the trumpet-shaped section 52. In this way, the flow-guiding effects are further improved. The flow-aligning ribs 62 are preferably arranged such that the flow-aligning ribs 62 and the fan 40 do not overlap when viewed in the radial direction (in the direction of arrow A in Fig. 4). In this way, a collision between the blades of the fan 40 and the flow-aligning ribs 62 can be avoided, even if the fan housing 50 is mounted slightly offset from a required position. The following describes the mode of operation of the device 10 for speed reduction. When a motor shaft of the (not shown) motor rotates, the input shaft coupled to the motor shaft is also rotated. As the input shaft rotates, the first intermediate shaft 32, the second intermediate shaft 36, and the output shaft 38 are rotated by meshing gears while the speed decreases. The rotation of these shafts is transmitted to a non-driven (not shown) machine. The fan 40, attached to the projecting section 12 of the drive shaft, is rotated, and air is drawn into the fan housing 50 through the opening section 53 on the non-load side. The intake air is conveyed radially outward as air currents by the rotation of the fan 40. The direction of these air currents is modified by the trumpet-shaped section 52 and the cylindrical section 54 of the fan housing 50. The flow of the air currents is straightened by the flow-aligning ribs 62, which are arranged on the inner surfaces of the trumpet-shaped section 52, and by the flow-aligning ribs 64, which are arranged on the inner surfaces of the cylindrical section 54.The airflows exiting the load-side opening section 58 of the fan housing 50 are directed so that they flow essentially parallel to the outer surface of the housing 30. Accordingly, the cooling effects for the area surrounding the housing 30, which contains the input shaft, the first intermediate shaft 32, and the bevel gear stage through which the input shaft meshes with the first intermediate shaft 32 (which exhibits the highest rotational speed and a high thermal load), are significantly improved. The cooling effects for the second intermediate shaft 36 are also enhanced by the parallel airflows. Fig. 5 is a perspective view of a speed reduction device 110 according to another embodiment of the present invention, viewed diagonally from the upper left. Fig. 6 is a perspective view of the speed reduction device 110 according to the other embodiment of the present invention, viewed diagonally from the lower left. The same reference numerals are assigned to the components of the speed reduction device 110 as to those of the speed reduction device 10 shown in Figs. 1 and 2, and a detailed description of these components is omitted. In the device 110 for speed reduction, a fan hood 150 with a shape that differs from that of the fan hood 50 is attached to an end section on a non-load side of the housing 30. Similar to the fan housing 50, the fan housing 150 comprises a trumpet-shaped section 152 having an inner surface that faces away from the input shaft towards the load side. A first cylindrical section 154, extending parallel to the input shaft, is connected to the non-load side of the trumpet-shaped section 152. A second cylindrical section 156, extending similarly parallel to the input shaft, is connected to the load side of the trumpet-shaped section 152. An inclined section 151, inclined towards the projecting section 12 of the input shaft, is connected to the non-load side of the first cylindrical section 154. An opening section 153 on the non-load side is formed on the smaller-diameter portion of the inclined section 151. A load-side opening section 158 is formed on the load side of the fan housing 150. In this embodiment, a gap of approximately 20 mm to approximately 50 mm is formed between the load-side opening section 158 and the outer surface of the housing 30. When the fan 40 is rotated, air is drawn into the fan housing 150 through the opening section 153 on the non-load side, and airflow is blown from the load-side opening section 158 towards the load side of the device 110 to reduce its velocity. More precisely, the trumpet-shaped section 152 of the fan housing 150 is configured to include a section 152a with an increasing diameter, having an inner surface inclined towards the load side away from the input shaft, and a flat section 152b with an inner surface parallel to the input shaft. A pair of the sections 152a with increasing diameter is arranged accordingly on the upper and lower surface sides of the housing 30. A pair of left and right flat sections 152b are present to connect the section 152a with increasing diameter on the upper surface side to the section 152a with increasing diameter on the lower surface side. The flat section 152b forms a continuous surface that is contiguous with the lateral surfaces of the first cylindrical section 154 and the second cylindrical section 156.As a result, in such a structure the cross-section of the trumpet-shaped section 152, perpendicular to the axis, has an octagonal shape. It is possible to reduce the time that the airflows generated by the fan 40 spend at the corners of the fan hood and to blow parallel airflows from the load-side opening section 158 of the fan hood 150 along the outer surface of the housing 30 by forming the trumpet-shaped section 152 in an octagonal shape approximating a circle, compared to a case in which the trumpet-shaped section has a rectangular cross-section. Figures 7 and 8 are a top and a front view, respectively, showing the non-load side of the speed reduction device 110. In Figures 7 and 8, a structure concealed by the fan cover 150 is indicated by the dashed line. As shown in the drawings, the increasing-diameter section 152a of the trumpet-shaped section 152 comprises a central increasing-diameter section 152a1 and left and right increasing-diameter sections 152a2, respectively, arranged on the left and right sides of the central increasing-diameter section 152a1. A flow-aligning rib 162 is arranged on an inner surface of the central increasing-diameter section 152a1 on its upper surface. In this embodiment, two flow-aligning ribs 162 are provided, but other numbers of flow-aligning ribs 162 may be provided. No flow-aligning ribs are provided on an inner surface of each of the left and right increasing-diameter sections 152a2 on their upper surface.No flow-aligning ribs are provided on the inner surface of any of the middle sections 152a1 with increasing diameter or of the left and right sections 152a2 with increasing diameter on the lower surface side. The stream of air currents generated by the fan 40 is aligned, and parallel air currents are generated along the outer surface of the housing 30 by the flow-aligning ribs on the inner surface of the fan hood 150. Flow-aligning ribs 164 can also be provided on the inner surfaces of the pair of flat sections 152b of the trumpet-shaped section 152, together with the provision of flow-aligning ribs 162 on the inner surface of the central section 152a1 with increasing diameter of the trumpet-shaped section 152. In this embodiment, three flow-aligning ribs 164 are provided on each of the pairs of left and right flat sections 152b, but a different number of flow-aligning ribs 164 can also be provided. Each of the flow-aligning ribs 162 can have an axial length greater than that of each of the flow-aligning ribs 164. In this way, the flow-aligning effects are further improved. Unlike the fan housing 50, the fan housing 150 does not have flow-aligning ribs on an inner surface of the second cylindrical section 156. This is because sufficient flow-aligning effects can be achieved by the flow-aligning ribs 164 arranged on the inner surfaces of the pair of flat sections 152b of the trumpet-shaped section 152. The flow-aligning ribs 162 and 164 do not overlap with the fan 40 when viewed in the radial direction. The following describes the mode of operation of the device 110 for speed reduction. When the motor shaft of the (not shown) motor rotates, the input shaft coupled to the motor shaft is also rotated. As the input shaft rotates, the first intermediate shaft 32, the second intermediate shaft 36, and the output shaft 38 are rotated by meshing gears while the speed decreases. The rotation of these shafts is transmitted to the undriven (not shown) machine. The fan 40, attached to the projecting section 12 of the drive shaft, rotates, and air is drawn into the fan housing 150 through the opening section 153 on the non-load side of the fan housing 150. The drawn-in air is conveyed radially outward as air currents by the rotation of the fan 40. The direction of the conveyed air currents is altered by the first cylindrical section 154, the trumpet-shaped section 152, and the second cylindrical section 156 of the fan housing 150.The airflow is aligned by the flow-aligning ribs 162 and 164, which are arranged on the inner surfaces of the trumpet-shaped section 152. Due to flow-aligning effects, the airflows exiting the load-side opening section 158 of the fan housing 150 are directed so that they flow essentially parallel to the outer surface of the housing 30. Accordingly, the cooling effects for the area surrounding the housing 30, which contains the input shaft, the first intermediate shaft 32, and the bevel gear stage through which the input shaft meshes with the first intermediate shaft 32 (which exhibits the highest rotational speed and a high thermal load), are significantly improved. The cooling effects for the second intermediate shaft 36 are also enhanced by the parallel airflows. Several embodiments of the present invention have been described. These embodiments have been cited as examples. As examples, a combination of the arranged components of the embodiment can be modified, and it is clear to those skilled in the art that the scope of the present invention includes the modified examples. In this embodiment, a device for speed reduction with a vertical axis is described as an example. The invention can be applied to other power transmission devices, including a device for speed reduction with parallel shafts and the like, provided that the other power transmission devices are designed such that a fan is provided on a projecting section of an input shaft that projects from a housing. The number or arrangement of flow-aligning ribs is not limited to the examples described in the embodiments. The number of flow-aligning ribs provided on the inner side of the trumpet-shaped section can be one, three, or more. Flow-aligning ribs can be provided on the inner surfaces of the left and right sections 52a2 with increasing diameter of the trumpet-shaped section 52, or on the inner surfaces of the left and right sections 152a2 of the trumpet-shaped section 152. The cross-sectional shape of the fan housing is not limited to an octagonal shape. Besides octagonal, the cross-sectional shape can also be polygonal, circular, or similar.

Claims

A speed reduction device (10, 110) comprising: a housing (30) accommodating a speed reduction mechanism, an input shaft comprising a projecting section (12) extending outward from the housing (30), a fan (40) arranged on the projecting section (12) of the input shaft, and a fan cover (50, 150) covering the fan (40), wherein the fan cover (50, 150) comprises a cylindrical section (54, 156) and a trumpet-shaped section (52, 152) connected to the cylindrical section (54, 156) and comprising an inner surface inclined such that it faces away from the input shaft toward a load side, and wherein a flow-aligning rib (62, 64, 162, 164) is provided on an inner surface of the trumpet-shaped section, and wherein the cylindrical section (54, 156) is provided on the load side of the trumpet-shaped section,wherein the flow-aligning rib (62, 64, 162, 164) provided on the inner surface of the trumpet-shaped section is spaced apart from the housing (30). A velocity reduction device (10, 110) comprising: a housing (30) accommodating a velocity reduction mechanism, an input shaft comprising a projecting section (12) extending outward from the housing (30), a fan (40) arranged on the projecting section (12) of the input shaft, and a fan hood (50, 150) covering the fan (40), wherein the fan hood (50, 150) comprises a cylindrical section (54, 154, 156) and a trumpet-shaped section (52, 152) connected to the cylindrical section (54, 154, 156) and comprising an inner surface inclined such that it faces away from the input shaft toward a load side, and wherein a flow-aligning rib (62, 64, 162, 164) is provided on an inner surface of the a trumpet-shaped section (52, 152) is provided, wherein the device (10, 110) is used for speed reduction in a state,in which a lower surface of the housing (30) is mounted on a base, wherein the trumpet-shaped section (52, 152) comprises a section (52a, 152a) with an increasing diameter having an inner surface inclined such that it faces away from the input shaft towards the load side, and a flat section (52b, 152b) having an inner surface parallel to the input shaft, wherein the trumpet-shaped section (52, 152) has a pair of the sections (52a, 152a) with increasing diameter arranged accordingly on an upper surface side and a lower surface side of the housing (30), respectively, wherein the trumpet-shaped section (52, 152) has a pair of the flat sections (52b, 152b), each of which is designed to connect the section (52a, 152a) with increasing diameter on the upper surface side to the section (52a, 152b) 152a) to connect with increasing diameter on the lower surface side,and wherein the flow-aligning rib (62, 64, 162, 164) is arranged on an inner surface of the section (52a, 152a) with increasing diameter on the upper surface side and the pair of flat sections (52b, 152b), and the flow-aligning rib is not arranged on an inner surface of the section (52a, 152a) with increasing diameter on the lower surface side. Device (10, 110) for reducing speed according to claim 2, wherein the flow-aligning rib (162, 164) is not provided on an inner surface of the cylindrical section (154, 156). Device (10, 110) for reducing speed according to one of claims 1 to 3, wherein at least a part of all flow-aligning ribs (62, 64, 162, 164) arranged on the inner surface of the trumpet-shaped section (52, 152) overlap each other in a circumferential direction. A speed reduction device (10) comprising: a housing (30) accommodating a speed reduction mechanism, an input shaft comprising a projecting section (12) extending outward from the housing (30), a fan (40) arranged on the projecting section (12) of the input shaft, and a fan hood (50) covering the fan (40), wherein the fan hood (50) comprises a cylindrical section (54) and a trumpet-shaped section (52) connected to the cylindrical section (54) and comprising an inner surface inclined such that it faces away from the input shaft toward a load side, and wherein a flow-aligning rib (62) is provided on an inner surface of the trumpet-shaped section (52), wherein the trumpet-shaped section (52) comprises a section (52a) with an increasing diameter having an inner surface inclined such thatthat it moves away from the input shaft towards the load side, and a flat section (52b) having an inner surface parallel to the input shaft, wherein a second flow-aligning rib (64) is arranged on an inner surface of the cylindrical section (54) connected to the flat section (52b), and simultaneously the flow-aligning rib (62) is arranged on an inner surface of the section (52a) having an increasing diameter. Device (10, 110) for reducing speed according to one of claims 1 to 5, wherein the flow-aligning ribs (62, 64, 162, 164) and the fan (40) do not overlap when viewed in a radial direction. A speed reduction device (110) comprising: a housing (30) accommodating a speed reduction mechanism, an input shaft comprising a projecting section (12) extending outward from the housing (30), a fan (40) arranged on the projecting section (12) of the input shaft, and a fan cover (150) covering the fan (40), wherein the fan cover (150) comprises a cylindrical section (154, 156) and a trumpet-shaped section (152) connected to the cylindrical section (154, 156) and comprising an inner surface inclined such that it faces away from the input shaft toward a load side, and wherein a flow-aligning rib (162, 164) is provided on an inner surface of the trumpet-shaped section (152), wherein the cylindrical section (154, 165) comprises a first cylindrical section (154)which is connected to a non-load side of the trumpet-shaped section (152), and comprises a second cylindrical section (156) which is connected to a load side of the trumpet-shaped section (152). A velocity reduction device (10, 110) comprising: a housing (30) accommodating a velocity reduction mechanism, an input shaft comprising a projecting section (12) extending outward from the housing (30), a fan (40) arranged on the projecting section (12) of the input shaft, and a fan hood (50, 150) covering the fan (40), wherein the fan hood (50, 150) comprises a cylindrical section (54, 154, 156) and a trumpet-shaped section (52, 152) connected to the cylindrical section (54, 154, 156) and comprising an inner surface inclined such that it faces away from the input shaft toward a load side, and wherein a flow-aligning rib (62, 162) is provided on an inner surface of the trumpet-shaped section (52, 152) is provided for, wherein the trumpet-like section (52, 152) is a section (52a,152a) with increasing diameter, which has an inner surface inclined such that it faces away from the input shaft towards the load side, and a flat section (52b, 152a) having an inner surface parallel to the input shaft, wherein the section (52a, 152a) with increasing diameter comprises a central section (52a1, 152a1) with increasing diameter, and left and right sections (52a2, 152a2) with increasing diameter, which are arranged accordingly on the left and right sides of the central section (52a1, 152a1) with increasing diameter, respectively, and the flow-aligning rib (62, 162) is arranged on an inner surface of the central section (52a1, 152a1) with increasing diameter. Device (10) for speed reduction according to one of claims 1 to 8, wherein the cylindrical section (54) comprises a cutout (70) through which a suspension aid is accessible.

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