Motor drive unit

Abstract

The motor drive device (100) includes a housing (1) whose interior space is divided by a partition (10) into an upper space (11) and a lower space (12), electronic components (30) arranged in the lower space (12) of the housing (1), and an internal fan (2) arranged in the upper space (11) of the housing (1) and discharging air from the interior space of the housing (1) to the outside. A first air vent (14) is formed in the top surface (1a) of the housing (1) to connect the upper space (11) to the outside of the housing (1), and a second air vent (15) is formed in a part of the partition (10) facing the top surface (1a) to connect the upper space (11) to the lower space (12). The internal fan (2) is arranged opposite the first air vent (14) and is arranged so that at least a part of the internal fan (2) does not overlap with the second air vent (15) when the housing (1) is viewed from the top surface (1a) side.

Description

[Technical Field]

[0001] The present disclosure relates to a motor drive device provided in a control panel. [Background technology]

[0002] Conventionally, motor drive devices equipped with fans for cooling electronic components inside a housing have been known. Motor drive devices are sometimes installed, for example, in control panels for industrial equipment. Factories where industrial equipment is installed often experience high humidity or oil mist caused by evaporation of oil used to cool and process the industrial equipment. In such factory environments, if the control panel is not properly sealed, oil mist or water vapor may enter the control panel. In this case, the oil mist or water vapor enters and circulates inside the housing due to the airflow generated by the fan. When the oil mist or water vapor is cooled by the fan, condensation occurs near the fan. If the droplets fall on electronic components placed inside the housing, the electronic components may suffer short circuit damage or malfunction due to oxidation or corrosion of the wiring patterns or components.

[0003] For example, the motor drive device disclosed in Patent Document 1 is configured with a heat sink inside the housing that cools power elements. Electronic components are placed below the heat sink inside the housing. The edge of the heat sink facing the electronic components is inclined with respect to the horizontal. Liquid droplets collected by a fan placed above the heat sink adhere to the heat sink, move along the inclined edge, and fall to a position away from the electronic components. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-154242 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology disclosed in Patent Document 1 is configured to cause droplets to fall inside the housing, so there is a risk that liquid condensed midway along the inclined portion of the heat sink or droplets blown away by the air flow circulating inside the housing may adhere to electronic components.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a motor drive device that can cool electronic components arranged inside a housing while suppressing droplets from falling into the housing. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the motor drive device according to the present disclosure is a motor drive device installed in a control panel, and includes a housing whose internal space is divided into an upper space and a lower space by a partition, electronic components arranged in the lower space of the housing, and an internal fan arranged in the upper space of the housing and discharging air in the internal space of the housing to the outside. A first air vent that connects the upper space with the outside of the housing is formed in the top surface of the housing, and a second air vent that connects the upper space with the lower space is formed in a part of the part that faces the top surface and forms the top surface of the partition that supports the internal fan. , facing the top surface of the housing where the first ventilation hole is formed. The internal fan is disposed opposite the first air vent and is disposed so that at least a portion of the internal fan does not overlap with the second air vent when the housing is viewed from above. [Effects of the Invention]

[0008] The motor drive device according to the present disclosure has the advantage of being able to cool electronic components arranged inside a housing while suppressing liquid droplets from falling into the housing. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a motor drive device according to a first embodiment; [Figure 2]FIG. 1 is an explanatory diagram showing an internal structure of a control panel in which a motor drive device according to a first embodiment is housed; [Figure 3] FIG. 1 is an exploded perspective view of a motor drive device according to a first embodiment; [Figure 4] 1 is a cross-sectional view showing the inside of a motor drive device according to a first embodiment; [Figure 5] FIG. 5 is a vertical cross-sectional view of the inside of the motor drive device according to the first embodiment, taken from a position different from that of FIG. 4; [Figure 6] FIG. 1 is an enlarged view showing an upper space of a housing of a motor drive device according to a first embodiment; [Figure 7] FIG. 1 is a perspective view schematically illustrating the inside of a housing of a motor drive device according to a first embodiment; [Figure 8] FIG. 1 is a cross-sectional view showing a first modification of an electronic component made of a capacitor component in a motor drive device according to a first embodiment; [Figure 9] FIG. 10 is a cross-sectional view showing a second modification of the electronic component made of a capacitor component in the motor drive device according to the first embodiment; [Figure 10] FIG. 10 is a partially exploded perspective view of a motor drive device according to a second embodiment; [Figure 11] FIG. 10 is a partially exploded perspective view of a first modification of the motor drive device according to the second embodiment; [Figure 12] FIG. 10 is a perspective view showing a second modification of the motor drive device according to the second embodiment; [Figure 13] FIG. 10 is a perspective view showing a third modification of the motor drive device according to the second embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a motor drive device according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0011] Embodiment 1 FIG. 1 is a perspective view showing a motor drive device according to a first embodiment. FIG. 2 is an explanatory diagram showing the internal structure of a control panel that houses the motor drive device according to the first embodiment. The white arrows in FIG. 2 indicate the flow of air passing through a heat sink 4. The motor drive device 100 shown in FIG. 1 controls the current flowing through a motor used in industrial equipment such as a robot, a machine tool, or a conveyor, thereby achieving desired motor motion. As shown in FIG. 2, the motor drive device 100 is installed in a control panel 200 for the industrial equipment. The control panel 200 is, for example, a power panel. In addition to the motor drive device 100, the control panel 200 also includes devices for utilizing electrical energy, such as relays, transformers, switches, circuit breakers, and switches (not shown). The devices arranged inside the control panel 200 are isolated from the outside of the control panel 200. In the motor drive device 100, a housing 1 that houses an internal fan and multiple electronic components is arranged inside the control panel 200, and a heat sink 4 and an external fan 5 are arranged exposed to the outside of the control panel 200.

[0012] FIG. 3 is an exploded perspective view of the motor drive device according to the first embodiment. FIG. 4 is a cross-sectional view showing the interior of the motor drive device according to the first embodiment. FIG. 5 is a vertical cross-sectional view of the interior of the motor drive device according to the first embodiment, taken from a different position than in FIG. 4. The white arrows in FIGS. 4 and 5 indicate the flow of air passing through the interior of the housing 1. As shown in FIGS. 3 to 5, the motor drive device 100 includes a housing 1, an internal fan 2, multiple electronic components 30 and 31, a heat sink 4, and an external fan 5.

[0013] The housing 1 has, for example, a substantially rectangular parallelepiped shape with a top surface 1a, a bottom surface 1b, and four side surfaces 1c, 1d, 1e, and 1f. The housing 1 has an opening formed in one of the four side surfaces 1c, 1d, 1e, and 1f, the side surface 1f, which is covered by a heat sink 4. The internal space of the housing 1 is divided into an upper space 11 and a lower space 12 by a plate-shaped partition 10 located opposite the top surface 1a of the housing 1. The upper space 11 of the housing 1 is a space surrounded by the top surface 1a and the side surfaces 1c, 1d, 1e, and 1f of the housing 1 and the partition 10, and functions as a duct for forming airflow. An internal fan 2 is housed in the upper space 11 to exhaust air heated in the internal space of the housing 1 to the outside and cool the internal space of the housing 1. The lower space 12 of the housing 1 is a space surrounded by the bottom surface 1b and side surfaces 1c, 1d, 1e, and 1f of the housing 1 and the partition 10, and houses a plurality of electronic components 30, 31 such as power modules and capacitor components. The shape of the housing 1 is not limited to the rectangular parallelepiped shape shown in the figure, and other shapes are also acceptable. The number of electronic components is also not limited to multiple, and may be one or more.

[0014] An opening 13a for inserting and removing the internal fan 2 is formed on the top surface 1a of the housing 1, and an internal fan cover 13 for covering the opening 13a is detachably provided. The internal fan cover 13 constitutes a part of the top surface 1a of the housing 1. The opening 13a is formed over almost the entire surface of the upper space 11. The opening 13a may be configured to be the same size as the internal fan 2. In this case, the internal fan cover 13 also has the same size as the internal fan 2. By removing the internal fan cover 13 from the housing 1, maintenance of the internal fan 2 and the upper space 11 of the housing 1 can be performed. The internal fan cover 13 is formed with a first air vent 14 that connects the upper space 11 of the housing 1 with the outside of the housing 1. The first air vent 14 is, for example, composed of a plurality of small holes. The internal fan 2 is disposed in the upper space 11 of the housing 1, facing the first air vent 14. It is not necessary to form the opening 13a on the top surface 1a of the housing 1 and provide the internal fan cover 13, and the housing 1 may be configured without the internal fan cover 13. In this case, the first ventilation hole 14 is formed on the top surface 1a of the housing 1.

[0015] A second air vent 15 is formed in the partition 10, connecting the upper space 11 and the lower space 12 of the housing 1. The second air vent 15 is, for example, composed of a plurality of small holes. The second air vent 15 is formed in a position where it does not overlap with the projected surface of the first air vent 14 when the housing 1 is viewed from the top surface 1a. It is preferable that the second air vent 15 is formed in a position where it does not overlap with the projected surface of the first air vent 14 when the housing 1 is viewed from the top surface 1a. However, the second air vent 15 may partially overlap with the projected surface of the first air vent 14. When performing maintenance on the motor drive device 100, the condition of the lower space 12 of the housing 1 can be easily visually confirmed through the second air vent 15 by removing the internal fan cover 13 from the housing 1.

[0016] As shown in FIGS. 4 and 5 , when the internal fan 2 is driven in the internal space of the housing 1, air in the lower space 12 of the housing 1 flows through the second air vent 15 into the upper space 11 and is then discharged to the outside of the housing 1 through the first air vent 14. At this time, the upper space 11 of the housing 1 functions as a duct that directs the air flow from the second air vent 15 to the first air vent 14, thereby strengthening the air flow without weakening it due to dispersion. Furthermore, since the second air vent 15 is formed in a part of the partition 10 that faces the top surface 1a on which the first air vent 14 is formed, there are fewer bends in the air path from the lower space 12 through the second air vent 15 to the first air vent 14. This reduces the deflection of the air flow, thereby reducing windage loss and effectively discharging the air inside the housing 1 to the outside of the housing 1.

[0017] Additionally, a third vent hole 16 is formed on the bottom surface 1b of the housing 1, connecting the lower space 12 of the housing 1 with the outside of the housing 1. As an example, the third vent hole 16 is composed of a plurality of small holes. The third vent hole 16 is preferably formed in a range including a position where the projected surface of the second vent hole 15 overlaps when the housing 1 is viewed from the top surface 1a. If the second vent hole 15 and the third vent hole 16 are on a straight line, the air flows in a straight line from the third vent hole 16 to the second vent hole 15 without being dispersed, thereby improving cooling efficiency. The third vent hole 16 may also be formed in a position where the projected surface of the second vent hole 15 does not overlap when the housing 1 is viewed from the top surface 1a. Furthermore, in consideration of cooling efficiency, it is preferable that the third vent holes 16 are formed only on the lower surface 1b, but for example, they may be formed only on at least one of the side surfaces 1c, 1d, and 1e, or they may be formed on at least one of the side surfaces 1c, 1d, and 1e and the lower surface 1b. Furthermore, the third vent holes 16 may be formed over a wider area than the second vent holes 15. For example, the third vent holes 16 may be formed over the entire surface of the lower surface 1b.

[0018] FIG. 6 is an enlarged view showing the upper space of the housing of the motor drive device according to the first embodiment. As shown in FIG. 6, the internal fan 2 is disposed opposite the first air vent 14 and is disposed at a position that does not overlap with the second air vent 15 when the housing 1 is viewed from the top surface 1a. That is, the internal fan 2 is disposed at a position away from the second air vent 15. The internal fan 2 is supported on the upper surface of the partition 10. The internal fan 2 draws air from the lower space 12 and generates an airflow that is exhausted from the housing 1 through the second air vent 15 in the partition 10 and the first air vent 14 formed on the top surface 1a of the housing 1 to the outside of the housing 1. The internal fan 2 is preferably disposed at a position that does not completely overlap with the second air vent 15 when the housing 1 is viewed from the top surface 1a. However, the internal fan 2 may be disposed so that at least a portion of the internal fan 2 does not overlap with the second air vent 15. That is, the internal fan 2 may be disposed at a position away from the second air vent 15.

[0019] As shown in FIG. 4, the electronic component 30 is, for example, a power module mounted on a power module mounting plate 30a and constituting a circuit for supplying power to a motor. The power module mounting plate 30a has heat transfer properties. As shown in FIG. 5, the electronic component 31 is a capacitor mounted on a printed circuit board 31a. The electronic components may include other electronic components in addition to the power module and capacitor electronic components 30, 31. The power module electronic component 30 and the capacitor electronic component 31 are heat sources and require cooling. As shown in FIG. 4, at least a portion of the power module electronic component 30 is disposed directly below the second air vent 15. As shown in FIG. 4, the electronic component 30 is disposed near the second air vent 15, near the upper portion of the lower space 12. When multiple power module electronic components 30 are disposed, they may be arranged across the lower space 12. As shown in FIG. 5, at least a portion of the capacitor electronic component 31 is disposed directly below the second air vent 15. Furthermore, the electronic components 31 are disposed near the upper portion of the lower space 12, near the second vent hole 15. These electronic components 30, 31 are disposed in an air passage extending from the third vent hole 16 toward the second vent hole 15. The air flow velocity increases near the second vent hole 15. Therefore, by disposing the electronic components 30, 31 near the second vent hole 15, the heated electronic components 30, 31 can be efficiently cooled. Furthermore, the air heated by cooling the electronic components 30, 31 can be immediately discharged to the second vent hole 15 without affecting other electronic components. Furthermore, by disposing the electronic components 30, 31 in the air passage extending from the third vent hole 16 toward the second vent hole 15, a large amount of air flows toward the electronic components 30, 31, thereby efficiently cooling the electronic components 30, 31. In consideration of cooling efficiency, the electronic components 30, 31 are preferably disposed directly below the second vent hole 15, but they do not necessarily have to be disposed directly below the second vent hole 15. However, even in this case, the electronic components 30, 31 are preferably disposed in the air path leading from the third vent hole 16 to the second vent hole 15.

[0020] FIG. 7 is a perspective view schematically illustrating the interior of a housing of a motor drive device according to the first embodiment. As shown in FIG. 7, an electronic component 30 including a power module may be supported on a vertically long power module mounting plate 30a. In this case, the power module mounting plate 30a is arranged such that the longitudinal direction of the mounting surface on which the power module is mounted is along the side surface 1d or 1e of the housing 1 along the air passage from the third air vent 16 to the second air vent 15. The electronic component 30 including the power module is arranged in the air passage from the third air vent 16 to the second air vent 15. Note that the side surface of the housing 1 along the air passage from the third air vent 16 to the second air vent 15 is perpendicular to the side surface 1f of the housing 1 attached to the wall portion 201 of the control panel 200 and perpendicular to the top surface 1a of the housing 1. By arranging the longitudinal direction of the installation surface of the vertically long power module installation plate 30a along the side surface 1d or 1e of the housing 1 along the air path from the third air vent 16 to the second air vent 15, the area in which electronic components 30 are installed along the third air vent 16 to the second air vent 15 can be increased, and many electronic components 30 can be cooled efficiently.

[0021] FIG. 8 is a cross-sectional view showing a first modification of an electronic component made of a capacitor in the motor drive device according to the first embodiment. Electronic component 32 shown in FIG. 8 is a large capacitor component and is arranged directly below second air vent 15. When electronic component 32 made of a large capacitor component becomes hot, the electrolyte may evaporate, potentially shortening its lifespan. By arranging electronic component 32 made of a large capacitor component directly below second air vent 15, electronic component 32 can be cooled efficiently.

[0022] 9 is a cross-sectional view showing a second modification of an electronic component made of a capacitor in the motor drive device according to the first embodiment. Electronic component 33 shown in FIG. 9 is a large capacitor component, and is a vertically elongated electrolytic capacitor whose longitudinal installation surface is arranged along the air passage from third air vent 16 to second air vent 15. By arranging electronic component 33 in this manner, the area exposed to air is increased and the electronic component can be arranged so as not to obstruct the air flow, thereby enabling electronic component 33 made of a large capacitor to be efficiently cooled.

[0023] The heat sink 4 dissipates heat generated by the electronic components 30, 31. As shown in FIGS. 4 and 5 , the heat sink 4 has a flat heat sink base 40 and a plurality of flat fins 41 arranged in parallel at intervals on one surface of the heat sink base 40. The heat sink 4 is made of a metal material with relatively high thermal conductivity so that it can dissipate heat generated by the electronic components 30, 31. As an example, the heat sink 4 is made of a corrosion-resistant metal material such as aluminum or an aluminum alloy. The heat sink 4 is fixed to the housing 1 so that the heat sink base 40 covers an opening formed in the side surface 1f of the housing 1. The fins 41 are surrounded by a fin cover 42 whose top and bottom surfaces are open.

[0024] As shown in FIG. 2, the external fan 5 is, for example, arranged above the heat sink 4, taking in air from the bottom of the heat sink 4 and pushing the air out from the top of the heat sink 4. The external fan 5 may also be arranged above the heat sink 4, taking in air from the top of the heat sink 4 and pushing the air out from the bottom of the heat sink 4. The external fan 5 may also be arranged below the heat sink 4, taking in air from the top or bottom of the heat sink 4 and pushing the air out from the bottom or top of the heat sink 4. Furthermore, if the amount of heat generated by the electronic components constituting the motor drive device 100 is small, a structure in which cooling is performed only by the internal fan 2 may be used, without providing the heat sink 4 and external fan 5.

[0025] As shown in FIG. 2 , the motor drive device 100 according to the first embodiment is mounted on a wall 201 that separates the inside of the control panel 200 from the outside of the control panel 200, with the fins 41 and the external fan 5 exposed to the outside of the control panel 200 through mounting holes (not shown) formed in the wall 201. During operation, the motor drive device 100 generates heat from the electronic components 30, 31 arranged inside the control panel 200. The generated heat is transferred to the outside of the control panel 200 through the fins 41 and is released, for example, into a factory where industrial equipment is installed, through heat exchange with air supplied by the external fan 5. Meanwhile, heat that is not transferred to the fins 41 remains in the internal space of the housing 1. The internal fan 2 creates an air flow inside the housing 1, and the heat remaining in the internal space of the housing 1 is released into the inside of the control panel 200. The heat released into the inside of the control panel 200 is released to the outside of the control panel 200 by a heat exchanger (not shown) or the like.

[0026] For example, factories where industrial equipment is installed are often filled with oil mist, which is the evaporated oil used to cool and process the industrial equipment, and are in a high humidity environment. In such an environment, if the control panel 200 installed in the factory is not sealed properly, there is a risk that oil mist or water vapor will enter the control panel 200.

[0027] At this time, the oil mist or water vapor enters and circulates inside the housing 1 due to the airflow generated by the internal fan 2. When the oil mist or water vapor is cooled by the action of the internal fan 2, condensation occurs near the internal fan 2, and if the droplets become large, they may fall due to gravity into the lower space 12 of the housing 1. If droplets form in the lower space 12, they may cause short circuits in the electronic components 30, 31 and other electronic components on the board, or may cause failure due to oxidation or corrosion of the wiring patterns or components.

[0028] Therefore, in the motor drive device 100 according to the first embodiment, the internal fan 2 is disposed opposite the first air vent 14 and is configured so that at least a portion of the internal fan 2 does not overlap with the second air vent 15 when the housing 1 is viewed from above. When oil mist or water vapor passes through the internal fan 2, it condenses, forming droplets on the blades of the internal fan 2, for example. As the droplets grow larger, they fall due to gravity. If the second air vent 15 is located directly below the internal fan 2, the droplets would fall into the lower space 12 of the housing 1. However, in the motor drive device 100 according to the first embodiment, the internal fan 2 is disposed so that at least a portion of the internal fan 2 does not overlap with the second air vent 15, so that the droplets fall onto the upper surface of the partition 10 directly below the internal fan 2. This prevents droplets from entering the lower space 12 of the housing 1, thereby protecting the electronic components 30, 31 and other electronic components disposed in the lower space 12. It is preferable that the second vent hole 15 is formed in a position that does not overlap at all with the projected surface of the first vent hole 14 when the housing 1 is viewed from the top surface 1a. However, even if the positions of the first vent hole 14 and the second vent hole 15 are shifted so that the second vent hole 15 partially overlaps with the projected surface of the first vent hole 14, it is possible to prevent liquid droplets from entering. In particular, since there is a high possibility that liquid droplets will fall from the center of the internal fan 2, by arranging the center of the internal fan 2 so that it does not overlap with the second vent hole 15, it is possible to significantly reduce the possibility of liquid droplets falling into the lower space 12.

[0029] The electronic components include electronic components 30, 31 that are arranged so that at least a portion of their outer surfaces is located directly below second ventilation hole 15. The air flow speed increases near second ventilation hole 15. This allows the heated electronic components 30, 31 to be cooled efficiently. Furthermore, the air that has become hot by cooling electronic components 30, 31 can be immediately discharged to second ventilation hole 15 without affecting other electronic components.

[0030] A third ventilation hole 16 is formed on the bottom surface of the housing 1. The electronic components 30, 31 include electronic components arranged in an air path extending from the third ventilation hole 16 to the second ventilation hole 15. This allows a large amount of air to flow through the electronic components 30, 31, allowing the electronic components 30, 31 to be cooled efficiently.

[0031] The electronic component 30 includes a power module supported by a power module mounting plate 30a. The power module mounting plate 30a has a mounting surface for mounting the power module arranged along side surface 1d or 1e of the housing 1 along the air passage from the third air vent 16 to the second air vent 15. The electronic component 30, which is made up of a power module, is arranged in the air passage from the third air vent 16 to the second air vent 15. By arranging the mounting surface of the power module mounting plate 30a along side surface 1d or 1e of the housing 1 along the air passage from the third air vent 16 to the second air vent 15 in this way, the area in which the electronic components 30 are mounted along the third air vent 16 to the second air vent 15 can be increased, and many electronic components 30 can be cooled efficiently.

[0032] Electronic component 33 includes an electrolytic capacitor whose installation surface is arranged along the air path from third vent 16 to second vent 15. By arranging electronic component 33 in this manner, the area exposed to air is increased and electronic component 33 can be arranged so as not to obstruct the air flow, allowing electronic component 33, which is a large capacitor, to be cooled efficiently.

[0033] Embodiment 2 Next, a motor drive device 101 according to a second embodiment will be described. FIG. 10 is a partially exploded perspective view of the motor drive device according to the second embodiment. As shown in FIG. 10, the motor drive device 101 according to the second embodiment has a liquid droplet fall prevention unit 6 in the upper space 11 of the housing 1 that receives liquid droplets generated on the internal fan 2. The rest of the configuration is the same as that of the first embodiment.

[0034] The droplet fall prevention unit 6 shown in FIG. 10 is a filter that is disposed below the internal fan 2 and absorbs droplets. Examples of filters include urethane, felt, water-absorbing polymer, nylon, polyester, or wool. The droplet fall prevention unit 6, which is made of a filter, is disposed between the internal fan 2 and the partition 10. By providing the droplet fall prevention unit 6, even when many droplets have accumulated on the upper surface of the partition 10 or when evaporation of the droplets is difficult, the filter can absorb the droplets, thereby preventing the droplets from falling into the lower space 12 of the housing 1.

[0035] FIG. 11 is a partially exploded perspective view of a first modification of the motor drive device according to the second embodiment. The droplet drop prevention unit 6A shown in FIG. 11 is a wall-like protrusion formed on the upper surface of the partition unit 10, blocking droplets attempting to flow into the second air vent 15. The droplet drop prevention unit 6A, which is a wall-like protrusion, is provided between the upper surface of the partition unit 10 facing the internal fan 2 and the second air vent 15. By providing the droplet drop prevention unit 6A, even when a large amount of droplets accumulates on the upper surface of the partition unit 10 or when droplet evaporation is difficult, the wall-like protrusion can block the flow of droplets, thereby preventing droplets from falling into the lower space 12 of the housing 1. In addition to providing the droplet drop prevention unit 6A, the droplet drop prevention unit 6, which is a filter as shown in FIG. 10, may be provided on the upper surface of the partition unit 10.

[0036] FIG. 12 is a perspective view showing a second modification of the motor drive device according to the second embodiment. Note that FIG. 12 shows a state in which the upper portion of the housing 1 is omitted and the partition 10 is exposed. The droplet drop prevention portion 6B shown in FIG. 12 is formed on the upper surface of the partition 10 and is configured as a recess for storing droplets. The droplet drop prevention portion 6B formed as a recess is formed in a position facing the internal fan 2. By providing the droplet drop prevention portion 6B, even when a large amount of droplets accumulates on the upper surface of the partition 10 or when evaporation of droplets is difficult, the droplets can be stored in the recess, thereby preventing droplets from falling into the lower space 12 of the housing 1. Note that the droplet drop prevention portion 6 formed as a filter shown in FIG. 10 may be installed inside the recess of the droplet drop prevention portion 6B. Alternatively, the droplet drop prevention portion 6A formed as a wall-like protrusion shown in FIG. 11 may be provided together with the droplet drop prevention portion 6B.

[0037] FIG. 13 is a perspective view showing a third modification of the motor drive device according to the second embodiment. Note that FIG. 13 shows a state in which the upper portion of the housing 1 is omitted and the partition 10 is exposed. The droplet drop prevention unit 6C shown in FIG. 13 is configured as a groove formed in the partition 10 to guide droplets to the outside of the housing 1. A portion of the droplet drop prevention unit 6C formed as a groove is formed in a position facing the internal fan 2. A drain hole 17 leading to the groove is formed in the side surface 1e of the housing 1. The droplets accumulated in the droplet drop prevention unit 6C are discharged to the outside of the housing 1 through the drain hole 17 and fall down the side surface 1e of the housing 1. Note that the droplet drop prevention unit 6 formed as a filter shown in FIG. 10 may be installed inside the groove of the droplet drop prevention unit 6C. Furthermore, the droplet drop prevention unit 6A formed as a wall-like protrusion shown in FIG. 11 may be provided together with the droplet drop prevention unit 6C.

[0038] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies or may be combined with other embodiments. Furthermore, it is also possible to omit or change part of the configurations without departing from the spirit of the invention. [Explanation of symbols]

[0039] 1 housing, 1a top surface, 1b bottom surface, 1c, 1d, 1e, 1f side surfaces, 2 internal fan, 4 heat sink, 5 external fan, 6, 6A, 6B, 6C droplet fall prevention section, 10 partition section, 11 upper space, 12 lower space, 13 internal fan cover, 13a opening, 14 first ventilation hole, 15 second ventilation hole, 16 third ventilation hole, 17 drainage hole, 30, 31, 32, 33 electronic components, 30a power module mounting plate, 31a printed circuit board, 40 heat sink base, 41 fin, 42 fin cover, 100, 101 motor drive device, 200 control panel, 201 wall section.

Claims

1. A motor drive device installed in a control panel, A housing whose internal space is divided into an upper space and a lower space by a partition, Electronic components arranged in the lower space of the aforementioned housing, An internal fan is provided in the upper space of the enclosure to expel air from the internal space of the enclosure to the outside, Equipped with, A first ventilation hole is formed on the upper surface of the housing, connecting the upper space with the outside of the housing, and a second ventilation hole is formed in a part of the partition facing the upper surface, connecting the upper space with the lower space. The internal fan is positioned opposite the first ventilation hole and, when the housing is viewed from the top, is positioned such that at least a portion of it does not overlap with the second ventilation hole. A motor drive device characterized by the following features.

2. The internal fan is positioned opposite the first ventilation hole and is positioned so as not to overlap with the second ventilation hole when the housing is viewed from the top side. The motor drive device according to feature 1.

3. The electronic component includes an electronic component that is positioned such that at least a portion of its outer surface is located directly below the second ventilation hole. The motor drive device according to feature 1.

4. A third ventilation hole is formed on the lower surface of the housing. The electronic component includes the electronic component located in the air passage from the third vent to the second vent. The motor drive device according to feature 1.

5. The aforementioned electronic components include a power module supported on a power module mounting plate. The power module mounting plate has a mounting surface for the power module positioned along the side of the housing that is aligned with the air passage from the third ventilation hole to the second ventilation hole. The power module is positioned in an air passage extending from the third vent to the second vent. The motor drive device according to feature 4.

6. The aforementioned electronic component includes an electrolytic capacitor whose mounting surface is arranged along an air passage from the third vent to the second vent. The motor drive device according to feature 4.

7. A drip prevention unit is provided in the upper space of the housing and is used to catch drips generated on the internal fan. A motor drive device according to any one of claims 1 to 6.

8. The aforementioned droplet fall prevention unit is positioned below the internal fan and is a filter that adsorbs droplets. The motor drive device according to feature 7.

9. The aforementioned droplet fall prevention part is a wall-shaped projection provided in the partition part that blocks droplets attempting to flow into the second ventilation hole. The motor drive device according to feature 7.

10. The aforementioned droplet fall prevention part is a recess formed in the partition part for storing the droplets. The motor drive device according to feature 7.

11. The aforementioned droplet fall prevention section is a groove formed in the partition section that guides the droplet to the outside of the housing. The motor drive device according to feature 7.

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