In-wheel motor housing structure

Abstract

In a housing structure of an in-wheel motor having a housing of an in-wheel motor, a vent hole for allowing air to circulate between the inside and outside of the housing, and a cover covering the vent hole from the outside of the housing, the cover has: an air hole located below an opening of the vent hole and opening to the outside of the cover; and an air chamber that holds air above the air hole, the air chamber being divided into a first region located above the opening and a second region located below the opening, the second region having a volume for holding air that suppresses the water level in the cover to a position below the opening when water penetrates into the cover through the air hole.

Description

Technical Field

[0001] The present invention relates to a structure of a housing for accommodating components of an in-wheel motor mounted on a vehicle as a driving force source. Background Art

[0002] Japanese Patent Application Laid-Open No. 2016-60422 describes an invention related to a vent structure for an in-wheel motor. This vent structure is designed to simplify the piping layout of a breather hose installed in the in-wheel motor's housing. The vent structure described in Japanese Patent Application Laid-Open No. 2016-60422 includes an in-wheel motor, a breather hose (a breather device and a tubular member connected to the breather device) that communicates with the inside of the in-wheel motor's housing and extends from the outside of the housing, a suspension member (a trailing arm) that mounts the in-wheel motor and supports it on a vehicle body side member, and a cover mounted on the suspension member and covering the breather hose. The breather hose is mounted to the suspension member together with the cover, with the opening at its tip positioned inside the cover. Summary of the Invention

[0003] In the ventilation structure for an in-wheel motor described in Japanese Patent Application Laid-Open No. 2016-60422, the opening at the top of the ventilation hose located within the engine compartment is conventionally positioned at the location of the suspension's trailing arm. This shortens the length of the ventilation hose, simplifying the piping layout. Furthermore, a cover covering the ventilation hose and attached to the trailing arm can be used to protect the ventilation hose from external foreign matter such as stones, sand, and dirt. However, in the ventilation structure for an in-wheel motor described in Japanese Patent Application Laid-Open No. 2016-60422, water could potentially intrude into the housing of the in-wheel motor through the ventilation hose.

[0004] For example, if a vehicle equipped with an in-wheel motor is traveling on a flooded road due to heavy rain or flooding, or in a situation such as off-road driving through standing water or a river, the entire vehicle tire could become submerged, effectively submerging the in-wheel motor. In such a situation, the trailing arm of the suspension could also become submerged. Therefore, in the in-wheel motor vent structure described in Japanese Patent Application Laid-Open No. 2016-60422, the vent hose attached to the trailing arm could also become submerged. Consequently, rainwater or muddy water could enter the in-wheel motor housing through the opening at the top of the vent hose. Furthermore, when the in-wheel motor becomes submerged, the temperature inside the housing decreases, causing the volume of the air inside to shrink. This decreases the pressure inside the housing, causing it to fall below atmospheric pressure. This creates a so-called negative pressure condition inside the housing. In such a situation, the vent hose could not only become submerged, but could also draw rainwater or muddy water into the in-wheel motor housing.

[0005] The present invention has been conceived with the above-mentioned technical problems in mind, and its object is to provide an in-wheel motor housing structure that can reliably prevent water from intruding into the inside of the in-wheel motor housing with a simple structure even in a situation where the vehicle tires are submerged.

[0006] In order to achieve the above-mentioned purpose, the present invention is a housing structure of an in-wheel motor, the housing structure of the in-wheel motor comprising: a housing, the housing forming an outer shell of the in-wheel motor mounted on a vehicle; a vent (for example, a ventilation device), the vent being provided in the housing and allowing air to circulate between the inner side of the housing and the outer side of the housing; and a cover covering the vent from the outer side of the housing, the housing structure of the in-wheel motor being characterized in that the vent has an opening portion in the cover that opens to the outer side of the housing, the cover having: an air hole, the air hole being located at a position vertically smaller than the opening of the opening portion The air chamber is located below the opening and opens to the outside of the cover; and an air chamber that holds air on the inner side above the opening position of the air hole in the vertical direction, the air chamber being divided into a first area located above the opening position of the opening in the vertical direction and a second area located below the opening position of the opening in the vertical direction, the second area having a volume for holding air that suppresses the water level in the cover in the vertical direction to a position below the opening position of the opening when the in-wheel motor is submerged and water seeps into the cover through the air hole.

[0007] In addition, the volume of the second area in the present invention may be larger than the volume equivalent to the maximum amount of air sucked into the shell from the opening when it is assumed that the temperature inside the shell decreases and the air (volume) inside the shell shrinks, that is, when the air inside the shell shrinks and the shell becomes under negative pressure.

[0008] Furthermore, the volume of the second region in the present invention may be larger than 20% of the volume of air present in the housing at room temperature (eg, approximately 20° C.).

[0009] Furthermore, the present invention may further include: a hood member that covers the surface of the shell from the outside of the shell and maintains a predetermined volume of air; and a connecting member that connects air between the inside of the hood member and the second area.

[0010] The in-wheel motor housing structure of the present invention includes a cover that covers and protects a vent hole that allows air to circulate between the inside and outside of the housing. The cover has an air hole formed at its vertically lower end when attached to the housing. The cover is open to the outside only at the portion of the air hole. Consequently, an air chamber is formed within the cover, vertically above the air hole, to retain the air within the cover. The air chamber can be divided into a first region above the vent hole and a second region below the vent hole. The second region has a volume sufficient to hold enough air to keep the vertical water level within the cover below the opening if water enters through the air hole. Therefore, even if water enters the cover, it is prevented from entering the housing through the vent hole. Therefore, even in situations where the in-wheel motor and the housing with the vent hole are submerged, the simple-shaped cover can easily prevent water from entering the housing.

[0011] Furthermore, in the in-wheel motor housing structure of the present invention, the air chamber, or cover, is formed so that the volume of the second region of the air chamber described above is larger than the volume corresponding to the amount of air that would be drawn into the housing if a so-called negative pressure were to occur within the housing. Therefore, for example, if the in-wheel motor is submerged, the temperature within the housing decreases, creating a negative pressure within the housing, and air within the cover is drawn into the housing. This prevents water from entering the first region within the cover. Therefore, even if the in-wheel motor is submerged and water enters the cover, the in-wheel motor housing structure of the present invention can reliably prevent water from entering the housing through the vent holes within the cover.

[0012] Furthermore, in the in-wheel motor housing structure of the present invention, the volume of the second region of the air chamber, as described above, is set, assuming, for example, that the temperature of the air within the housing drops from approximately 70°C to approximately 20°C—a temperature difference of approximately 50°C and a change in the volume of the air by approximately 18.3%. Specifically, the air chamber, or cover, is formed such that the volume of the second region of the air chamber is greater than 20% (≈18.3%) of the volume of the air within the housing at a normal temperature of approximately 20°C. Therefore, if, for example, the in-wheel motor is submerged during operation, the temperature within the housing drops from a high temperature of approximately 70°C to approximately 20°C, and the volume of the air within the housing decreases by approximately 18.3%, resulting in a negative pressure within the housing, water intrusion into the first region within the cover is prevented. Therefore, even if the in-wheel motor is submerged and water enters the cover, the in-wheel motor housing structure of the present invention reliably prevents water from entering the housing through the vent holes within the cover.

[0013] Furthermore, in the housing structure of the in-wheel motor of the present invention, a protective cover member (or other cover member) is provided that covers the surface of the housing from the outside of the housing of the in-wheel motor and retains a predetermined volume of air in the inner portion, and a connecting member that connects the air between the inner portion of the protective cover member and the second region of the air chamber as described above. The second region of the air chamber and the interior of the protective cover member are connected in an airtight state through the connecting member. Therefore, the volume of the portion that retains air in the protective cover member can be added to the volume of the second region of the air chamber. Thus, the degree of freedom in setting the volume of the second region of the air chamber can be increased. Therefore, according to the housing structure of the in-wheel motor of the present invention, even in a situation where the in-wheel motor is submerged and the housing equipped with the vent hole is also submerged, it is possible to easily prevent water from intruding into the inner side of the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0015] Figure 1 This is a diagram for explaining the structure of the housing structure of the in-wheel motor of the present invention, and is a three-dimensional diagram showing the appearance of the housing structure of the in-wheel motor of the present invention (the vent hole and the opening of the vent hole in a state where the cover is removed).

[0016] Figure 2 This is a diagram for explaining the construction of the housing structure of the in-wheel motor of the present invention, and is a perspective view showing the appearance of the housing structure of the in-wheel motor of the present invention (the positional relationship between the vent hole and the cover when the cover is installed).

[0017] Figure 3 This is a diagram for explaining the structure of the housing of the in-wheel motor according to the present invention, and is a perspective view showing the positional relationship between the opening position of the vent opening and the opening position of the air hole of the cover in the vertical direction.

[0018] Figure 4 It is a diagram for illustrating the structure of the housing structure of the in-wheel motor of the present invention, a cross-sectional view showing details of the vent hole and cover in the housing structure of the in-wheel motor of the present invention, and a cross-sectional view showing a state where the housing of the in-wheel motor is submerged.

[0019] Figure 5 It is a diagram for illustrating the construction of the housing structure of the in-wheel motor of the present invention, is a cross-sectional view showing details of the vent hole and cover in the housing structure of the in-wheel motor of the present invention, and is a cross-sectional view showing a state in which, when the housing of the in-wheel motor is submerged, the inner side of the housing becomes a negative pressure and a predetermined amount of air is sucked in from the vent hole.

[0020] Figure 6This is a diagram for explaining the construction of the housing structure of the in-wheel motor according to the present invention, and is a perspective view showing an example in which a connecting member is provided to connect the interior of the protective cover member for protecting the cable with the second region in the air chamber within the cover. DETAILED DESCRIPTION

[0021] The embodiment of the present invention will be described with reference to the drawings. The embodiment described below is merely an example of a case where the present invention is embodied, and does not limit the present invention.

[0022] The in-wheel motor that is the subject of the housing structure of the in-wheel motor in the embodiment of the present invention is mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle. The in-wheel motor is an integral assembly of the motor with the wheel hub or axle shaft to which the wheel is mounted, and is mounted on the vehicle body together with the wheel body via a suspension device (suspension mechanism). As an example of the in-wheel motor in the embodiment of the present invention, Figure 1 、 Figure 2 、 Figure 3 2 shows a motor unit (in-wheel motor) 1 which is a combination of a motor and a reduction mechanism. Figure 1 、 Figure 2 、 Figure 3 The motor unit 1 shown is composed of a driving motor (not shown) housed in a housing 2 and a speed reduction mechanism (not shown) for amplifying the torque of the motor.

[0023] In addition, the motor constituting the motor unit 1 is composed of, for example, a permanent magnet synchronous motor or an induction motor. The motor has at least the function of being a prime mover that is driven by being supplied with electric power and outputs torque. In addition, the motor can also function as a generator that is driven by receiving torque from the outside to generate electric power. That is, the motor can be a so-called electric generator that has both the function of a prime mover and the function of a generator. A battery (not shown) is connected to the motor via a converter (not shown). Therefore, the electric power stored in the battery is supplied to the motor, so that the motor functions as a prime mover and outputs a driving torque. In addition, the torque transmitted from the wheels (not shown) can be used to make the motor function as a generator, and the regenerative power generated at this time can be stored in the battery. Moreover, the motor can be regeneratively controlled during driving, and the wheels can be braked using the regenerative torque generated at this time.

[0024] In addition, the reduction mechanism is composed of, for example, a reduction gear pair (not shown) provided between two parallel shafts (not shown). Specifically, the reduction mechanism has a driving gear (not shown) mounted on the rotating shaft (not shown) of the motor and a driven gear (not shown) mounted on the output shaft (not shown) of the motor unit 1 and meshing with the driving gear. The diameter of the driven gear is larger than the diameter of the driving gear, and the number of teeth of the driven gear is greater than the number of teeth of the driving gear. Therefore, the gear pair of these driving gears and the driven gear constitutes a reduction mechanism that reduces the rotation speed of the rotating shaft (rotor shaft) of the motor, that is, amplifies the output torque of the motor. In addition, in Figure 1 、 Figure 2 、 Figure 3 In the illustrated embodiment, a wheel hub 3 is mounted on the output shaft of the reduction mechanism, i.e., the output shaft of the motor unit 1. The wheel body (not shown) of the wheel is mounted on this wheel hub 3. Furthermore, the in-wheel motor in the embodiments of the present invention is not limited to the motor unit 1 described above. For example, a motor unit comprising a planetary gear mechanism or other reduction mechanism and a motor may also be employed. Alternatively, an in-wheel motor may be constructed in which the wheel body is directly mounted on the motor without using a reduction mechanism.

[0025] As described above, the housing 2 accommodates the components of the reduction mechanism, coils, stators, rotors, etc. (none of which are shown in the figure), and the motor. In other words, the housing 2 forms the outer shell of the motor unit 1, that is, the in-wheel motor in the embodiment of the present invention. Oil (not shown) is injected into the interior of the housing 2 for lubricating and cooling the motor and reduction mechanism of the motor unit 1. Therefore, in order to prevent the oil from leaking from the housing 2, the housing 2 is sealed using sealing materials, packings, etc. (none of which are shown in the figure). However, when the motor unit 1 is running and the temperature inside the housing 2 rises, the pressure inside the sealed housing 2 also rises. Therefore, a vent hole 4 is provided in the housing 2 for suppressing the rise of excess pressure in the housing 2.

[0026] like Figure 4 As shown, the vent hole 4 is formed by a cylindrical member. The vent hole 4 is in the vertical direction ( Figure 4 The vent hole 4 is formed on the upper portion of the housing 2 in the vertical direction and penetrates the inner side of the housing 2 and the outer side of the housing 2. Therefore, the vent hole 4 has a Figure 4 The lower side of the housing 2) and the outer side of the housing 2 ( Figure 4The portion opening to the outside of the housing 2 is referred to as the opening 5 in the embodiment of the present invention. Thus, the vent 4 allows air to circulate between the inside and outside of the housing 2. For example, when the motor unit 1 operates and the temperature inside the housing 2 rises, the volume of the air inside the housing 2 expands accordingly. The expanded air is released from the opening 5 of the vent 4 to the outside of the housing 2. Consequently, a rise in pressure inside the housing 2 is suppressed.

[0027] Furthermore, in the housing structure of the in-wheel motor in the embodiment of the present invention, as Figure 2 、 Figure 3 、 Figure 4 As shown, in order to prevent water and foreign matter from intruding into the housing 2 through the opening 5 of the vent hole 4, a cover 6 is provided that covers the vent hole 4 from the outside of the housing 2. The cover 6 is attached to the housing 2 so as to cover the vent hole 4 from the outside of the housing 2. For example, the cover 6 is made of a resin or metal having predetermined rigidity and strength, is formed separately from the housing 2, and is attached to the outer surface of the housing 2. Alternatively, the cover 6 is formed integrally with the housing 2 so as to cover the vent hole 4 from the outside of the housing 2. For example, the cover 6 is formed integrally with the housing 2 so as to provide an air chamber 7 inside the cover 6, which will be described later.

[0028] In addition, in the above Figure 2 、 Figure 3 and the following Figure 6 In the figure, for convenience, the outline of the shape of the cover 6 is shown by a two-dot chain line so that the vent hole 4 covered by the cover 6 can be seen through. Figure 1 In the figure, for convenience, the state where the cover 6 is omitted or the state before the cover 6 is installed is shown. Figure 2 、 Figure 3 and the following Figure 6 In the embodiment, the cover 6 is in a rectangular parallelepiped shape. However, the shape of the cover 6 in the embodiment of the present invention is not limited to such a rectangular parallelepiped shape, and may be, for example, a cylindrical shape or a hemispherical shape.

[0029] Furthermore, the cover 6 in the embodiment of the present invention includes the air chamber 7 and the air holes 8 .

[0030] The air chamber 7 is a space formed inside the cover 6, and when the cover 6 is mounted on the housing 2 or when the cover 6 is formed integrally with the housing 2, air is retained inside the cover 6. Figure 4 An air hole 8, which will be described later, is formed below the cover 6 in the vertical direction. Therefore, the air chamber 7 is configured to hold air at a position above the opening position of the air hole 8 on the inner side of the cover 6 in the vertical direction.

[0031] Furthermore, the air chamber 7 is divided into a first region 9 and a second region 10. The first region 9 is the region of the air chamber 7 located vertically above the opening position of the opening portion 5 of the vent hole 4 when the cover 6 covers the vent hole 4. The second region 10 is the region of the air chamber 7 located vertically below the opening position of the opening portion 5 of the vent hole 4 when the cover 6 covers the vent hole 4.

[0032] The air hole 8 is formed at a position vertically below the opening position of the opening of the vent hole 4 so as to open to the outside of the cover 6. Therefore, the air inside the cover 6, that is, the air in the air chamber 7, can flow between the inside and outside of the cover 6 through the air hole 8.

[0033] As described above, the air chamber 7 of the cover 6 is provided with the second region 10 located vertically below the opening position of the opening portion 5 of the vent hole 4. Figure 4 As shown, this second region 10 has a volume V of air sufficient to hold enough air to suppress the vertical water level within cover 6 to a position below the opening position of opening 5 of vent hole 4 when motor unit 1 is submerged and water enters cover 6 through air hole 8 of cover 6. In other words, cover 6 is formed so as to secure the aforementioned volume V as the volume of second region 10 within air chamber 7 of cover 6.

[0034] Specifically, the volume V of the second region 10 is greater than the volume equivalent to the maximum amount of air sucked into the shell 2 from the opening of the vent 4 when it is assumed that the temperature inside the shell 2 of the motor unit 1 decreases and the volume of the air inside the shell 2 shrinks (that is, when the air inside the shell 2 shrinks and the shell 2 becomes a so-called negative pressure).

[0035] For example, if motor unit 1 is submerged during operation, the temperature of the air within housing 2 may drop from approximately 70°C to approximately 20°C, resulting in a temperature difference of approximately 50°C within the air within housing 2. As previously described, housing 2 is provided with vent holes 4 to maintain a substantially constant pressure within housing 2. Therefore, as described above, if the air within housing 2 experiences a temperature difference of approximately 50°C, and the coefficient of thermal expansion of air is calculated as "0.00366 / K," it can be estimated that the volume of the air within housing 2 changes by approximately 18.3%. If the temperature of the air within housing 2 drops from approximately 70°C to approximately 20°C, it can be estimated that the volume of the air within housing 2 decreases by approximately 18.3%. Therefore, in the housing structure of the in-wheel motor according to the embodiment of the present invention, air chamber 7, i.e., cover 6, is formed such that the volume V of second region 10 within air chamber 7 of cover 6 is greater than, for example, 20% (≈18.3%) of the volume of air within housing 2 at a normal temperature of approximately 20°C. Therefore, for example, if the operating motor unit 1 is submerged, the temperature inside the housing 2 drops from a high temperature of approximately 100°C to approximately 20°C. Consequently, the volume of air inside the housing 2 decreases by approximately 18.3%, creating a negative pressure inside the housing 2. This prevents water from entering the first region 9 of the cover 6, specifically, the opening 5 of the vent hole 4 in the cover 6. Therefore, the housing structure of the in-wheel motor according to the embodiment of the present invention reliably prevents water from entering the housing 2 through the vent hole 4 in the cover 6, even if the motor unit 1 is submerged and water enters the cover 6.

[0036] Figure 6 Another example of the housing structure of the in-wheel motor in the embodiment of the present invention is shown. Figure 6 The motor unit 1 shown in the figure has the same structure and function as the above-mentioned Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 The same components or parts as those in the motor unit 1 shown in FIG. Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 The same reference numerals are used in the drawings.

[0037] Figure 6 The motor unit 1 shown in FIG. Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 In addition to the illustrated configuration, a shield member 11 and a connecting member 12 are further provided.

[0038] The protective cover member 11 covers the surface of the shell 2 from the outside of the shell 2 and maintains a predetermined volume of air. For example, in order to protect the cables (not shown) arranged on the outer surface of the shell 2, the protective cover member 11 covers the surface of the shell 2 and the cables from the outside of the shell 2. The protective cover member 11 is a cover member (different from the cover 6) that is formed separately from the shell 2 and installed on the outer surface of the shell 2 using a resin or metal having predetermined rigidity and strength as a material. A sealing material or a packing (not shown) is provided between the outer surface of the shell 2 and the protective cover member 11 to prevent water and foreign matter from intruding into the inner side of the protective cover member 11. Therefore, a predetermined volume of air is maintained in the space inside the protective cover member 11.

[0039] The connecting member 12 communicates air between the interior of the protective cover member 11 and the second region 10 in the air chamber 7 of the cover 6. For example, the connecting member 12 is formed of a hard tubular member or a flexible tubular or hose-shaped member. The two ends of the connecting member 12 are connected to the cover 6 and the protective cover member 11, respectively, in a manner that allows air to circulate. That is, the second region 10 of the cover 6 and the interior of the protective cover member 11 are connected in an airtight state through the connecting member 12. Therefore, the volume of the portion of the protective cover member 11 that retains air can be added to the volume of the second region 10 in the air chamber 7. As a result, the degree of freedom in setting the volume of the second region 10 in the air chamber 7 can be increased.

[0040] As described above, the housing structure of the in-wheel motor in the embodiment of the present invention includes a cover 6 that covers and protects the vent hole 4 that allows air to circulate between the inside and outside of the housing 2. The cover 6 has an air hole 8 formed at its vertically lower end when attached to the housing 2. The cover 6 is open to the outside only at the portion of the air hole 8. Consequently, an air chamber 7 is formed within the cover 6, vertically above the air hole 8, to retain the air within the cover 6. The air chamber 7 can be divided into a first region 9 above the vent hole 4 and a second region 10 below the vent hole 4. The second region 10 has a volume sufficient to retain air, keeping the vertical water level within the cover 6 below the opening 5 of the vent hole 4 in the event of water intrusion through the air hole 8. Therefore, even if water intrudes into the cover 6, it is prevented from entering the housing 2 through the vent hole 4 within the cover 6.

[0041] Therefore, according to the housing structure of the in-wheel motor in the embodiment of the present invention, even in a situation where the motor unit 1 (in-wheel motor) is submerged and the housing 2 equipped with the vent 4 is also submerged, water can be easily prevented from intruding into the inner side of the housing 2 by the cover 6 of the simple shape as described above.

Claims

1. A housing structure for an in-wheel motor, comprising: a housing forming an outer shell of the in-wheel motor mounted on a vehicle; a vent provided in the housing for allowing air to flow between an inner side of the housing and an outer side of the housing; and a cover covering the vent from the outer side of the housing. The housing structure of the in-wheel motor is characterized in that: The vent hole has an opening portion that opens to the outside of the housing in the cover. The cover has an air hole located vertically below the opening of the opening portion and opening to the outside of the cover; and an air chamber that holds air at a position vertically above the opening position of the air hole, The air chamber is divided into a first region located vertically above the opening of the opening and a second region located vertically below the opening of the opening. The second region has a volume for holding air sufficient to suppress the vertical water level in the cover to a position below the opening position of the opening when the in-wheel motor is submerged and water enters the cover through the air hole. The air hole is located vertically below the second region as a whole. The housing structure of the in-wheel motor further comprises: a protective cover member covering the surface of the housing from the outside of the housing and retaining a predetermined volume of air, wherein the protective cover member is a cover member different from the cover and is formed separately from the housing and attached to the outer surface of the housing, and is made of a resin or metal having predetermined rigidity and strength; as well as A connecting member that connects air between the interior of the protective cover member and the second area, the connecting member being formed by a hard tubular member or a flexible tubular or hose-shaped member, the two ends of the connecting member being connected to the cover and the protective cover member respectively in a manner that allows air to circulate.

2. The housing structure of the in-wheel motor according to claim 1, characterized in that: The volume of the second region is larger than a volume corresponding to the maximum amount of air that is sucked into the housing through the opening when it is assumed that the air in the housing contracts as the temperature in the housing decreases.

3. The housing structure of the in-wheel motor according to claim 2, characterized in that: The volume of the second region is larger than 20% of the volume of air existing in the housing at normal temperature.

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