WATERPROOF COVER

Abstract

Waterproof cover comprising: a cover unit (1b) having a vent hole (10) that allows an inner surface and an outer surface of the cover unit to connect and is configured to cover an electronic component (6); and a filter (F) that is attached to the inner surface of the cover unit in a state in which it is opposite an inner open end section (10a) of the vent hole and is configured to block the flow of a liquid while allowing the flow of air through it, wherein the outer surface of the cover unit has a surface (15) with a surface (14a) in which an outer open end section (10b) of the vent hole is exposed, and the surface (15) has a region formed at a position adjacent to the vent hole (10) and having a height that differs from a height of the surface (14a).in which the area with the different height is formed with a concave section (16) which is recessed in a curved shape in a section of the surface (14a), several ventilation holes (10) are arranged along an outer circumferential direction of the concave section (16) and the concave section has a projection (16a) which is formed in a central section of the concave section (16).

Description

TECHNICAL FIELDThis disclosure relates to a waterproof cover including a lid unit having a vent hole that allows an inner surface and an outer surface of the lid unit to communicate with each other, and a filter that blocks a liquid from flowing while allowing air to flow therethrough.BACKGROUNDA waterproof cover that covers a space in which a circuit board for driving an electric pump is accommodated has a risk of damage when a load acts on a lid unit due to a sudden change in temperature in the space due to expansion and contraction of air, and there is a risk that water (a liquid) penetrates from a damaged area.Thus, as a conventional waterproof cover covering a circuit board, a technology is proposed in which a vent hole (also referred to as a breathing hole) formed straight is provided from the outer surface to the inner surface of a lid unit (also referred to as a cover), and a filter is attached to the inner surface of the lid unit in a state of facing the inner open end portion of the vent hole (see, e.g., JP 2017-034880 A (Document 1)). The filter has a property of blocking the flow of a liquid while allowing air to flow therethrough. Thereby, damage to the lid unit is prevented, and intrusion of a liquid into the inside of the lid unit is prevented by keeping the inside and the outside of the lid unit at the same pressure.However, the waterproof cover for the electric pump mounted on a vehicle is often disposed in a state of being exposed to the outside, and the liquid that sprays up from the road surface may directly hit the lid unit. At this time, in a structure having a vent hole formed straight, as in the waterproof cover of the document 1, the jetted liquid can directly enter the vent hole, causing a high water pressure to act on the filter, and there is a risk of damage to the filter by the water pressure. As a result, the liquid comes into contact with electronic components on the board disposed inside the lid unit, causing the electric pump to fail.Although it is conceivable to install a separate component covering the vent hole opposite to the outside of the lid unit to prevent a liquid from entering the separate component, this increases manufacturing cost and the size of the electric pump also increases.DE 10 2011 004 760 A1 discloses an electronic device for a vehicle, which has at least one electronic device, a waterproof housing which accommodates the at least one electronic device, and a filter. The housing has a ventilation hole that passes through a housing wall of the housing. A wall surface of the ventilation hole includes an inclined surface portion having an increasing cross-sectional area that progressively increases from an inner end toward an outer end of the inclined surface portion toward an outer surface of the housing wall in a direction of passage of the ventilation hole.EP 2 848 813 B1 discloses an electric pump in which respective vent through holes have a slot shape elongated in a radial direction of a vent cap body. In a bottom surface of each of the vent through holes, an inclined surface is formed in the vicinity of a radially inner end portion, so that the position of the radially inner end portion is higher than that of a radially outer end portion. A vent filter is installed at a portion around an inner opening portion of a vent recessed portion so as to close the opening portion of the vent recessed portion. The air vent filter has a waterproof property and allows passage of air for air venting.Thus, there is a need for a waterproof cover capable of reliably preventing damage to the filter with a simple configuration.This object is achieved by a watertight cover having the features of claim 1.A feature of a configuration of a waterproof cover according to an aspect of this disclosure is that the waterproof cover includes a lid unit that has a vent hole allowing an inner surface and an outer surface to communicate with each other and is configured to cover an electronic component; and a filter that is fixed to the inner surface of the lid unit in a state facing an inner open end portion of the vent hole and configured to block a flow of a liquid while allowing a flow of air therethrough. The outer surface of the lid unit has a surface including a surface in which an outer open end portion of the vent hole is exposed, and the surface includes a region formed at a position adjacent to the vent hole and having a height different from a height of the surface.In this configuration, a region having a height different from that of the surface having the outer open end portion of the vent hole is formed on the outer surface of the lid unit at a position adjacent to the vent hole in the surface. Thus, when a liquid directly hits the lid unit, a part of the liquid is reflected from the region having the different height, and the reflected liquid collides with the liquid directly entering the vent hole. As a result, the pressure of the liquid directly entering the vent hole is equalized, and the pressure and the amount of the liquid directly entering the vent hole and directly hitting the filter are decreased. Thus, damage to the filter due to direct impingement of the liquid on the filter can be prevented.In addition, with a simple configuration in which the region having the different height is provided in the surface as in this configuration, since a separate component covering the vent hole does not need to be installed, manufacturing cost can be reduced, and an increase in size of the device can be prevented. Moreover, due to the configuration in which the pressure of the liquid on the outside of the lid unit is reduced, the vent hole does not need to have a complicated shape to reduce the pressure of the liquid, and the lid unit can be manufactured with a simplified shape divided into upper and lower shapes.The region having the different height is formed with a concave portion recessed in a curved shape in a portion of the surface.When the region having the different height from the concave portion recessed in a portion of the surface is formed as in this configuration, the region can be easily processed. In addition, since the concave portion does not protrude outward, the size of the device does not increase. Moreover, when the concave portion is formed in a curved shape, since the liquid directly incident on the concave portion is obliquely reflected from the curved surface as a reflection surface, the possibility that the obliquely reflected liquid collides with the liquid directly entering the vent hole is increased. Thus, the pressure and the amount of the liquid directly hitting the filter can be reliably reduced.A plurality of the vent holes are arranged along an outer circumferential direction of the concave portion, and the concave portion has a protrusion formed in a central portion of the concave portion.Since a plurality of the vent holes are formed, air permeability is good. In addition, when the protrusion is provided in the central portion of the curved concave portion as in this configuration, in addition to the liquid obliquely reflected from the curved surface near the outer periphery of the concave portion, the liquid obliquely reflected from the curved surface near the protrusion may collide with the liquid directly entering the vent hole. As a result, the possibility that the liquid obliquely reflected from the curved surface collides with the liquid entering the vent hole can be further increased, and the pressure and the amount of the liquid directly hitting the filter can be further decreased.In this way, a waterproof cover that can reliably prevent damage to the filter with a simple configuration can be provided.In another configuration, a plurality of the vent holes may be provided, and the inner open end portions of respective vent holes may communicate through a space formed between the inner open end portions and the filter.When the inner open end portions of the respective vent holes communicate through the space formed between the inner open end portions and the filter as in this configuration, even if a foreign matter in the liquid enters a vent hole, the foreign matter can be discharged through the space from the other vent holes. Thus, air permeability can be prevented from being deteriorated due to the foreign matter adhering to the filter.In another configuration not according to the invention, the region having the different height may be formed with a first wall portion protruding from a portion of the surface and a plurality of second wall portions arranged around the first wall portion and protruding from a portion of the surface. The vent holes are separately disposed between the first wall portion and the respective second wall portions.In this configuration, since the vent holes are separately disposed between the first wall portion and the respective second wall portions, a plurality of the vent holes are present, and air permeability is good. In addition, in this configuration, when the region having the different height is formed of the first wall portion and the plurality of second wall portions arranged around the first wall portion, since a plurality of wall portions are present at different positions, the liquid directly incident on the first wall portion and the second wall portions is reflected at different angles. Accordingly, the possibility that the liquid reflected from the first wall portion and the second wall portions collides with the liquid entering the vent hole disposed between the first wall portion and the second wall portions can be further increased. Moreover, since the plurality of second wall portions are disposed around the first wall portion, an air gap may be formed between the respective adjacent second wall portions, and the liquid reflected by the first wall portion or the second wall portions or the liquid colliding with the reflected liquid to enter the vent hole may be discharged to the outside of the air gap. Thus, the pressure and the amount of the liquid directly hitting the filter can be more reliably reduced.BRIEF DESCRIPTION OF THE DRAWINGSThe above and additional features and characteristics of the disclosure will become apparent from the following detailed description with reference to the accompanying drawings. The following are shown: FIG. 1 is a cross-sectional view of a water pump; FIG. 2 is a perspective view of a waterproof cover according to a first embodiment; FIG. 3 is an enlarged cross-sectional view of the waterproof cover according to the first embodiment; FIG. 4 is a schematic view showing a state in which a liquid directly impinges on the waterproof cover; FIG. 5 is a perspective view of a waterproof cover according to a second embodiment not according to the present invention; FIG. 6 is an enlarged cross-sectional view of a surface according to another embodiment 1; FIG. 7 is an enlarged cross-sectional view of a surface according to another embodiment 2; FIG. 8 is an enlarged cross-sectional view of a surface according to another embodiment 3; and FIG. 9 is an enlarged cross-sectional view of a surface according to another embodiment 4.DETAILED DESCRIPTIONHereinafter, embodiments of a waterproof cover will be described with reference to the drawings. In the present embodiment, an example of a waterproof cover including a cover case 1 b(an example of a cover unit) covering a circuit board 6 of an electric pump P configured as a water pump will be described. However, the disclosure is not limited to the following embodiments, and various modifications may be made.< Configuration>As shown in FIG. 1, the electric pump P includes a housing 1, a shaft member 2 having an end 2 asupported by the housing 1, a rotor 3 provided on an outer periphery of the shaft member 2 rotatably about the rotation axis X, an impeller 4 fixed to a flange-shaped tip end portion 34 of the rotor 3, and an impeller housing 5 in which the impeller 4 is accommodated. The other end of the shaft member 2 is supported by the impeller shell 5. The electric pump P is configured such that the impeller 4 draws and discharges cooling water when the rotor 3 is rotated by the driving force of an electric motor M. For example, the electric pump P circulates the cooling water to an inverter, or circulates the cooling water between an internal combustion engine and a radiator. In the present embodiment, the electric motor M is configured as a three-phase brushless motor including the rotor 3 configured to rotate about the rotation axis X and a stator 7 configured to generate magnetic flux with respect to the rotor 3.The housing 1 includes a resin motor housing 1 athat forms a rotor chamber 3 ain which the rotor 3 is rotatably accommodated, and the resin cover housing 1 bthat forms a control chamber 6 ain which the circuit board 6 (an example of an electronic component) that controls the electric motor M is accommodated. The motor housing 1a has a partition wall 1c integrally formed therein so as to partition the rotor chamber 3a and the control chamber 6a from each other. The end 2 aof the shaft member 2 is fixed to the partition wall 1 cin an injection molded state. In addition, the stator 7 disposed so as to surround the radially outer side of the rotor 3 is formed in the motor housing 1 aby injection molding.The rotor 3 includes an annular rotor core 31 formed by stacking a plurality of magnetic steel plates and a plurality of permanent magnets 31 aembedded in the rotor core 31. The rotor core 31 and the permanent magnets 31 aare insert molded with a resin and integrated with each other. In the present embodiment, a permanent magnet 3 bis formed to have six poles, and the electric motor M is a motor having six poles, three phases, and nine slots. In addition, a plurality of inclined grooves (not shown) inclined in the circumferential direction are formed in the tip end portion of the rotor 3, and the impeller 4 is fixed to the inclined grooves by vibration welding or the like.In the present embodiment, control of a current to a winding C wound around the stator 7 via the circuit board 6 is performed by a motor control unit (ECU) of a vehicle (not shown), whereby the rotor 3 is rotated by the alternating magnetic field acting on the permanent magnet 31 a. When the rotor 3 rotates, the impeller 4 fixed to the tip end portion 34 of the rotor 3 also rotates. The impeller 4 is covered by the impeller housing 5 made of resin.When the electric pump P is mounted on the vehicle, the lid housing 1 bis often disposed in a state of being exposed to the outside, and water (an example of a liquid) is sometimes directly incident on the lid housing 1 b. Therefore, the lid housing 1 bis tightly fixed to the motor housing 1 ain a state of covering the circuit board 6. A method of fixing the lid housing 1 band the motor housing 1 ato each other is not limited, and a method of waterproofly screwing them with a sealing member interposed therebetween, thermal welding or vibration welding, or the like may be used. When the control chamber 6a for ensuring that it is waterproof is sealed, for example, thermal stress may act on the lid housing 1b by expansion and contraction of air due to sudden change in temperature of the circuit board 6, and there is a risk of damage to the lid housing 1b. To prevent this, a plurality of vent holes 10 are provided in the lid case 1b, and the control chamber 6a (the inside of the lid case 1b) is maintained at atmospheric pressure.In addition, the waterproof cover has a filter F that is fixed to the inner surface of the lid housing 1 bin a state of facing an inner open end portion 10 a(the control chamber 6 aside end portion) of the vent hole 10. The filter F is, for example, a vent filter that prevents water from flowing while air can flow therethrough. This prevents water from entering the control chamber 6a from the vent hole 10. In the present embodiment, the filter F is fixed to the inner surface of the lid case 1 bby thermo-welding the outer peripheral portion of the filter F.< Embodiment>A waterproof cover according to a first embodiment will be described with reference to FIGS. 2 to 4. As shown in FIGS. 2 and 3, the lid housing 1 bincludes a flange portion 11 fixed to the motor housing 1 a, an annular upright portion 12 vertically protruding from the flange portion 11, and an upper plate portion 13 having a rectangular shape in a plane extending inward from the upright portion 12. The upper plate portion 13 has a pillar portion 14 formed to protrude outward in a pillar shape, and the pillar portion 14 has the plurality of vent holes 10 (in the present embodiment, at four equidistant positions in the circumferential direction) formed to pass through the back side of the pillar portion 14. The vent holes 10 allow the outer surface and the inner surface of the lid housing 1 b(the pillar portion 14) to communicate with each other.In addition, a surface 15 having a surface 14 a(the same plane as the outer open end portions 10 bof the vent holes 10) in which the outer open end portions 10 b(the end portions on the outside) are exposed is formed on the outermost surface of the pillar portion 14. Here, the surface 14a denotes a plane continuing to the outer open end portions 10b of the vent holes 10, but this plane may have a slightly curved surface or the like. In addition, on the back side of the pillar portion 14, a convex portion 14 bis formed to protrude inward (see FIG. 3 ). Alternatively, the pillar portion 14 protruding outward in a pillar shape may protrude in a polygon shape, or may be formed by the same plane as the top plate portion 13, instead of protruding. Alternatively, the upper plate portion 13 is not limited to a rectangular shape in a plan view, and may have any shape such as a circular shape in a plan view.The surface 15 has a region formed at a position adjacent to the outer open end portions 10 bof the vent holes 10 and having a height different from that of the surface 14 a. In the present embodiment, the region having the different height is formed by a concave portion 16 recessed in a curved shape in a portion of the surface 14 a. The concave portion 16 is provided in a central region 15 athat is surrounded by the outer open end portions 10 bof the plurality of vent holes 10, and a protrusion 16 awith an arc surface is formed in the central portion of the concave portion 16 so as to protrude outward. In other words, the plurality of vent holes 10 are arranged along the outer periphery of the concave portion 16. In addition, the concave portion 16 does not need to have a curved shape, but may be formed with a U-shaped cross section.The vent holes 10 are formed with straight-formed first vent holes 10A formed on the inner open end portion 10 aside and straight-formed second vent holes 10B formed on the outer open end portion 10 bside. The first vent holes 10A and the second vent holes 10B are disposed at positions offset from each other in the radial direction. That is, the upper outer circumferential end surfaces of the first vent holes 10A and the lower inner circumferential end surfaces of the second vent holes 10B are joined to each other to form the vent holes 10 bent in a cross-sectional view. Thereby, a labyrinth structure is formed in which the water pressure hardly acts directly on the filter F. In addition, the vent holes 10 may also be formed straight instead of being bent.The respective first vent holes 10A are separated from each other by the convex portion 14 bformed on the rear side of the pillar portion 14. In addition, a communication space 10C (an example of a space) is formed such that the inner open end portions 10 aof the respective first vent holes 10A can communicate with each other. The communication space 10C is formed between the convex portion 14 band the filter F and is covered with the filter F. Thereby, even when water containing foreign matter enters one vent hole 10, the foreign matter can be ejected from the other vent holes 10 through the communication space 10C. Thus, deterioration of air permeability due to foreign matters adhering to the filter F can be prevented. In addition, since the lid housing 1 bcan be manufactured with the vent holes 10 using a lower mold for forming the first vent holes 10A and the communicating space 10C and an upper mold for forming the second vent holes 10B, a special mold that requires a complicated extraction structure does not need to be used to form the vent holes 10 having the labyrinth structure.As shown in FIG. 4, when water directly impinges on the top plate portion 13 (the surface 15) of the lid housing 1 b, the water is obliquely reflected along the curved surface of the concave portion 16. As a result, the water obliquely reflected from the concave portion 16 collides with the water entering the vent holes 10, thereby equalizing the pressure of the water directly entering the vent holes 10 and reducing the amount of water. Therefore, the pressure and the amount of water directly impinging on the filter F are reduced, which can prevent damage to the filter F. Specifically, when the protrusion 16 ais provided in the central portion of the curved concave portion 16, as in the present embodiment, in addition to the water reflected from the outer circumferential surface of the concave portion 16, the water is also reflected from the protrusion 16 a. Accordingly, since the water directly incident on the concave portion 16 is reflected at different angles, the possibility of collision with the water entering the vent holes 10 can be further increased.In practice, as a result of a high pressure water injection test carried out according to IS020653 IPX6K or IPX9K, the filter of the waterproof cover of the present embodiment was not damaged. On the other hand, when the concave portion 16 was not provided in the surface 15, damage of the filter F was detected. In addition, the waterproof cover of the present embodiment has also passed a predetermined ventilation test. Since the concave portion 16 does not protrude outward beyond the surface 15 when the ventilation test is performed, the ventilation test can be performed in a state where an air supply unit (not shown) is in contact with the surface, and the efficiency of the ventilation test can be increased. In addition, since in the present embodiment, the lid housing 1 bis manufactured using a simple upper and a simple lower mold and the filter F needs to be fixed to the inner surface of the lid housing 1 bvia only thermal welding, it is not necessary to install a separate component covering the vent holes 10, and manufacturing costs can be reduced and a compact apparatus can be obtained.< Embodiment>A waterproof cover according to a second embodiment not according to the present invention will be described with reference to FIG. 5. Since a basic configuration is the same as that of the above-described embodiment, only the differences will be described with reference to the drawings. In addition, for facilitating understanding of the drawings, the same names and reference numerals as in the above-described embodiment are used.The region having the height different from that of the surface 14 aand formed in the surface 15 is disposed in the central region 15 athat is surrounded by the outer open end portions 10 bof the plurality of vent holes 10, and is formed with a first wall portion 17 athat protrudes from a portion of the surface 14 aand a plurality of second wall portions 17 b(at four positions in the present embodiment) that are provided on the radially outer side of the outer open end portions 10 bof the respective vent holes 10 and around the first wall portion 17 aand protrude from portions of the surface 14 a. The first wall portion 17 aand the second wall portions 17 bare formed in a rectangular parallelepiped shape so as to protrude outward from the surface 14 a. In addition, the end portions of the respective second wall portions 17 bare spaced apart from each other, and they have a plurality of air gaps (in the present embodiment, at four positions). In other words, the respective vent holes 10 are separately disposed between the first wall portion 17 aand the respective second wall portions 17 b, and a rectangular connection path 18 through which water can flow is formed between the first wall portion 17 aand the second wall portions 17 band connected to the air gaps. Thus, water in the communication path 18 passes through the air gaps and is discharged radially outward. Alternatively, one of the first wall portion 17 aand the second wall portions 17 bmay be omitted, or a single second wall portion 17 bmay be provided, without the disclosure being limited thereto.When the region having a height different from that of the surface 14 ais formed with the first wall portion 17 aand the second wall portions 17 bas in the present embodiment, since the plurality of wall portions 17 aand 17 bare present at different positions, the water directly incident on the first wall portion 17 aand the second wall portions 17 bis reflected at different angles. As a result, the possibility of collision between the water reflected from the first wall portion 17 aand the second wall portions 17 band the water introduced into the vent holes 10 can be increased. Moreover, since the end portions of the second wall portions 17 bare spaced apart from each other, the water reflected by the first wall portion 17 aor the second wall portions 17 bor the water entering the vent holes 10 colliding with the reflected water can be discharged to the outside from the air gaps through the communication path 18. Thus, the pressure and the amount of water directly impinging on the filter F can be reduced. Moreover, since the water flowing through the communication path 18 is quickly discharged from the air gaps, no water accumulates around the vent holes 10.In practice, the filter F was not damaged in a high pressure water injection test according to IS020653 IPX6K or IPX9K in the waterproof cover of the present embodiment. The other effects are the same as those of the above-described embodiment, so a description thereof will be omitted.< Embodiments>Other embodiments will be described below with reference to FIGS. 6 to 9. Since a basic configuration is the same as that of the above-described embodiment, only differences will be described with reference to the drawings. For facilitating understanding of the drawings, the same names and reference numerals as in the above-described embodiment are used.(1) Instead of the concave portion 16 of the first embodiment, as shown in FIG. 6, the region having a height different from that of the surface 14 amay be formed by a curved convex portion 20 curvedly protruding from a part of the surface 14 a. Alternatively, the curved convex portion 20 need not be formed as a curved surface, but may have a polygonal cross section with multiple edges.(2) As shown in FIG. 7, a concave portion 20 athat is recessed in the central portion of the curved convex portion 20 may be provided.(3) As a modification of the second embodiment not according to the present invention shown in FIG. 8, a first inclined surface 17 a 1 whose height decreases toward the vent hole 10 may be formed at the outer end of the first wall portion 17 a. In addition, a second inclined surface 17 b 1 whose height decreases toward the vent hole 10 may be formed at the outermost end of the second wall portion 17 b.(4) As shown in FIG. 9, a third inclined surface 17 a 2 whose height increases toward the vent holes 10 may be formed at the outermost end of the first wall portion 17 a. In addition, a bent surface 17 b 2 may be formed at the outermost ends of the second wall portions 17 b. In addition, the region having a height different from that of the surface 14 amay have a suitably combined shape of the shapes mentioned in connection with the embodiments described above, without being limited thereto.(5) The waterproof cover according to the present embodiment is not limited to use in the electric pump P, and may be suitably used as long as it covers an electronic component such as an oil pump or a transmission.The present disclosure may be applied to a waterproof cover that seals electronic components of various devices.The foregoing has described the principles, preferred embodiments and modes of operation of the present invention. However, the invention is not intended to be limited to the particular embodiments. The embodiments are illustrative only and are not intended to be limiting. Variations and changes may be made without departing from the scope of the invention. Accordingly, all such variations, changes and equivalents are intended to be included within the scope of the present invention as defined by the claims.It is expressly emphasized that all features disclosed in the description and / or the claims are to be regarded as separate and independent from each other for the purpose of original disclosure as well as for the purpose of restricting the claimed invention independently of the combinations of features in the embodiments and / or the claims. It is expressly stated that all statements of groups of entities disclose every possible subset of entities for the purpose of original disclosure as well as for the purpose of limiting the claimed invention.

Claims

A waterproof cover comprising: a lid unit (1b) having a vent hole (10) allowing an inner surface and an outer surface of the lid unit to communicate with each other and formed to cover an electronic component (6); and a filter (F) fixed to the inner surface of the lid unit in a state of facing an inner open end portion (10a) of the vent hole and formed to block a flow of a liquid while allowing a flow of air therethrough, wherein the outer surface of the lid unit has a surface (15) having a surface (14a) in which an outer open end portion (10b) of the vent hole is exposed, and the surface (15) has a region formed at a position adjacent to the vent hole (10) and having a height, which is different from a height of the surface (14a), in which the region having the different height is formed with a concave portion (16) which is recessed in a curved shape in a portion of the surface (14a), a plurality of vent holes (10) are arranged along an outer circumferential direction of the concave portion (16), and the concave portion has a protrusion (16a) which is formed in a central portion of the concave portion (16).The waterproof cover according to claim 1, wherein a plurality of vent holes (10) are provided, and the inner open end portions of respective vent holes are communicated with each other through a space (10C) formed between the inner open end portions and the filter (F).

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