Breather structure for oil-cooled motor

Abstract

To provide a breather structure for an oil-cooled motor that is able to restrict pressure fluctuation in a housing and is able to surely prevent entry of foreign matter from outside by exhibiting an excellent filtering function.SOLUTION: A breather 11 is attached to a housing 3 of an oil-cooled motor 1 mounted on an electric vehicle as a power source for traveling, and the inside of the housing 3 is allowed to communicate with outside through a filter 12 of the breather 11. A cooling passage 15 is formed in the housing 3 so as to allow the filter 12 to communicate with the inside of the housing 3, and a breather water passage 16 is formed adjacent to the cooling passage 15. An inner peripheral surface of the cooling passage 15 is cooled through a partition 14a by distributing cooling water from a cooling inverter water passage 4 of an inverter 2 and circulating the cooling water through the breather water passage 16. The flow rate of the cooling water in the breather water passage 16 can be adjusted according to a degree of opening of a flow-rate adjustment valve 18.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a breather structure for an oil-cooled motor. [Background technology]

[0002] The motors installed in electric and hybrid vehicles (hereafter collectively referred to as "electric vehicles") as a power source for driving the vehicle generate heat during operation and therefore require cooling. Therefore, in this type of oil-cooled motor, oil is circulated within the motor housing to prevent overheating. Furthermore, since the pressure inside the housing fluctuates with temperature changes, the housing is equipped with a pressure regulator to maintain a constant internal pressure.

[0003] For example, a one-way valve may be used as a pressure regulating device. One-way valves are configured to allow air to flow only from inside the housing to the outside, thereby preventing external water, dust, and other particles (hereinafter referred to as foreign matter) from entering the housing. However, one-way valves do not allow external air to be sucked in even when the air inside the housing contracts due to a drop in temperature, which creates a negative pressure inside the housing and allows external foreign matter to enter. Therefore, an oil cap with a labyrinth structure may be used instead of a one-way valve.

[0004] For example, Patent Document 1 discloses an air breather device as an oil cap, in which a plurality of plate members are arranged in a row along the axis inside a cylindrical portion, and each plate member is disposed at a different position as viewed from the axial direction. Also, Patent Document 2 discloses an outlet hole as an oil cap, in which an implanted portion made of countless fibers is provided on the inner wall surface.

[0005] The inside and outside of the housing are connected via these air breather devices and outlet holes, which suppresses pressure fluctuations within the housing. At the same time, the plate members in Patent Document 1 and the bristle section in Patent Document 2 each prevent lubricating oil and the like from being blown out of the housing and also prevent foreign matter from entering from the outside. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-48926 [Patent Document 2] JP 2018-146000 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the labyrinth structure employed in the oil caps of Patent Documents 1 and 2 merely complicates the route, and cannot be expected to provide the same good filtering function as a so-called filter. Therefore, for example, if water splashes onto the housing while the vehicle is running, foreign matter such as water or dust contained in the water will slip through the plate member of Patent Document 1 or the flocked portion of Patent Document 2. This creates the possibility that foreign matter that gets inside could cause a motor malfunction.

[0008] The present invention has been made to solve these problems, and its purpose is to provide a breather structure for an oil-cooled motor that can suppress pressure fluctuations within the housing and perform excellent filtering functions to reliably prevent the intrusion of foreign matter from the outside. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the breather structure of an oil-cooled motor of the present invention is an oil-cooled motor that is installed in an electric vehicle as a power source for driving and is cooled by circulating oil within a housing, and is characterized by comprising: a breather attached to the housing and connecting the inside of the housing to the outside via a filter; a cooling passage formed in the housing and connecting the inside of the housing to the filter; and a breather waterway formed adjacent to the cooling passage and allowing cooling water to circulate to cool the inner surface of the cooling passage.

[0010] With this breather structure for an oil-cooled motor, the filter prevents foreign matter such as water and dust from entering the housing from the outside. When the internal pressure of the housing increases, the air inside the housing passes through the filter and is expelled to the outside. While the air may contain oil smoke or oil mist generated inside the housing, the oil smoke or oil mist is liquefied and separated from the air as it flows through the cooling passage, preventing oil from adhering to the filter.

[0011] In another aspect, a plurality of fins may be provided on the inner peripheral surface of the cooling passage in a protruding manner. Therefore, the fins increase the contact area between the inner circumferential surface of the cooling passage and the air, making it possible to cool the air efficiently. In another aspect, the oil-cooled motor may further include a flow rate adjustment unit that adjusts the amount of cooling water flowing through the breather water passage, and a controller that controls the flow rate adjustment unit, and the controller may be configured to cause the flow rate adjustment unit to increase the amount of cooling water flowing through the breather water passage when the oil-cooled motor is operating in a predetermined oil smoke generation range compared to other operating ranges.

[0012] Therefore, in the oily smoke generation range, the amount of oily smoke generated inside the housing is greater than in other operating ranges, but at this time the amount of cooling water flowing through the breather water passage increases, allowing the air to be cooled efficiently and the oily smoke to be liquefied and separated. Also, in other operating ranges the amount of cooling water flowing decreases relatively, reducing the load on the cooling water pump to circulate the cooling water.

[0013] In another aspect, the oil-cooled motor may further include a flow rate adjustment unit that adjusts the amount of cooling water flowing through the breather water passage, and a controller that controls the flow rate adjustment unit, and the controller may be configured to cause the flow rate adjustment unit to increase the amount of cooling water flowing through the breather water passage when the oil-cooled motor is operating in a predetermined oil mist generation range compared to other operating ranges.

[0014] Therefore, in the oil mist generation range, the amount of oil mist generated inside the housing is greater than in other operating ranges, but at this time the amount of cooling water flowing through the breather water passage increases, allowing the air to be cooled efficiently and the oil mist to be liquefied and separated. Also, in other operating ranges, the amount of cooling water flowing decreases relatively, reducing the load on the cooling water pump to circulate the cooling water.

[0015] In another aspect, the oily smoke generating region may be set in a high load region of the motor. Therefore, the amount of cooling water flowing through the breather water passage increases when the motor is in a high load range. In another aspect, the oil mist generation region may be set in a high rotation range of the motor.

[0016] Therefore, the amount of cooling water flowing through the breather water passage increases when the motor is in the high rotation speed range. In another aspect, the controller may be configured to cause the flow rate adjustment unit to stop the flow of cooling water through the breather water passage when the SOC of the driving battery, which is the power source for the motor, is less than a predetermined SOC judgment value, or when an SOC preservation mode that preserves the SOC of the driving battery is selected as the driving mode of the electric vehicle.

[0017] Therefore, when the SOC is below the SOC judgment value or when the SOC preservation mode is selected, it can be considered that reducing power consumption from the driving battery should be prioritized over preventing filter clogging. At this time, the flow of coolant through the breather channel is stopped, reducing the load on the coolant pump. In another aspect, the housing may include an inverter that controls the drive of the motor, the inverter may be cooled by cooling water circulating through an inverter waterway, and the flow rate adjustment unit may be a flow rate adjustment valve that diverts the cooling water circulating through the inverter waterway to the breather waterway side depending on the opening degree.

[0018] Therefore, since the cooling water in the existing inverter water passage is diverted to the breather water passage side, there is no need to provide a dedicated cooling water pump or radiator for the breather water passage. [Effects of the Invention]

[0019] The breather structure for an oil-cooled motor of the present invention can suppress pressure fluctuations within the housing, and also exhibits excellent filtering function to reliably prevent foreign matter from entering from the outside. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is an overall configuration diagram showing an oil-cooled motor to which a breather structure according to an embodiment is applied; [Figure 2] 2 is a cross-sectional view taken along line II-II in FIG. 1, showing the breather attachment position of the housing. [Figure 3] FIG. 10 is a characteristic diagram of a motor showing the generation region of oily smoke and oil mist. [Figure 4] 4 is a flowchart showing a valve opening control routine executed by a controller. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described, in which the present invention is embodied in a breather structure for an oil-cooled motor mounted on an electric vehicle as a power source for driving the vehicle. FIG. 1 is a diagram showing the overall configuration of an oil-cooled motor to which the breather structure of this embodiment is applied. The oil-cooled motor 1 (hereinafter simply referred to as the motor) of this embodiment is housed in a housing 3 together with an inverter 2. The motor 1 is configured as a three-phase AC motor, and includes a stator 1a around which coils for each phase are wound, and a rotor 1b equipped with a magnet is rotatably supported within the stator 1a. An output shaft 1c of the rotor 1b protrudes from the housing 3, and although not shown, when mounted in an electric vehicle, the output shaft 1c is connected to left and right drive wheels via a transaxle with a speed reduction function and a drive shaft. Note that the configuration of the housing 3 is not limited to this; for example, the housing 3 may house only the motor 1, or may house a speed reducer in addition to the motor 1 and inverter 2.

[0022] The motor 1 is drive-controlled by an inverter 2. For example, during power running control, DC power from a traction battery (not shown) is converted into three-phase AC power by the inverter 2 and supplied to the motor 1, which operates to drive the left and right drive wheels via a transaxle and drive shaft. During regenerative control, rotation of the left and right drive wheels is transmitted to the motor 1 via the drive shaft and transaxle, and the three-phase AC power generated by the motor 1 is converted into DC power by the inverter 2 and charged into the traction battery.

[0023] An inverter water passage 4 is attached to the inverter 2 to prevent overheating. More specifically, the inverter 2 is housed in the upper part of the housing 3, and an internal water passage 4a is formed in the housing 3 along the underside of the inverter 2. One end of the internal water passage 4a is connected to the other end via an external water passage 4b to form the inverter water passage 4, and a cooling water pump 5 and a radiator 6 are installed on the external water passage 4b.

[0024] The cooling water discharged from the cooling water pump 5 flows from the external water passage 4b to the internal water passage 4a, receives heat from the inverter 2 and increases in temperature, then flows through the radiator 6 in the external passage 4b, exchanges heat with the outside air and decreases in temperature, before being sucked back into the cooling water pump 5. The inverter 2 is cooled by this circulation of the cooling water. Note that in practice, the rotation speed and other parameters of the cooling water pump 5 are controlled in accordance with various conditions such as the temperature of the cooling water, but this is not directly related to the gist of the present invention and therefore will not be described in detail.

[0025] Like the inverter 2, the motor 1 is also cooled, using oil as a cooling medium instead of cooling water. Although its configuration is well known and not shown, a motor oil passage is formed in the housing 3 so as to surround the stator 1a. Oil circulates through this motor oil passage to cool the motor 1 and prevent it from overheating, and the oil is also used to lubricate bearings and other components within the housing 3.

[0026] As mentioned above, the pressure inside the housing 3 fluctuates in response to temperature changes, and therefore a pressure regulating device for maintaining a constant internal pressure is provided in the housing 3. In the oil-cooled motors described in Patent Documents 1 and 2, a labyrinth-structured oil cap (air breather device, outlet hole) is used as the pressure regulating device, but there is a possibility that foreign matter such as water or dust from the outside can slip through and enter the housing 3.

[0027] In view of the above-mentioned problems, the present inventors have focused on the breathers used in general water-cooled motors. For example, as shown in Figure 2, this type of breather 11 is provided on one side of the housing 3 and maintains a constant pressure near atmospheric pressure inside the housing 3 by connecting the inside of the housing 3 to the outside via a built-in filter 12. In addition, the filter 12 has excellent filtering capabilities and can reliably capture foreign matter from the outside, such as water and dust, and prevent it from entering the housing 3.

[0028] However, simply adapting the breather 11 to the oil-cooled motor 1 causes another problem. In the oil-cooled motor 1, oil smoke is generated from the oil due to heat from the coils and the like, and the oil is also scattered by the rotor 1b rotating at high speed, generating oil mist, which fills the housing 3. Therefore, when the air inside the housing 3 is exhausted to the outside through the filter 12, the oil smoke contained in the air condenses on the filter 12, and the oil mist adheres to the filter 12, resulting in the filter 12 becoming clogged with oil and quickly losing its filtering function.

[0029] To address this issue, the breather structure of this embodiment is provided with a breather water passage 16 for cooling the air flowing from the housing 3 to the filter 12, and details of this structure will be described below. 2 is a cross-sectional view taken along line II-II in FIG. 1, showing the breather attachment position of the housing 3, with the lower side in the drawing corresponding to the inside of the housing 3 and the upper side corresponding to the outside.

[0030] 1 and 2, a mounting hole 13 is formed through the outer wall 3a of the housing 3 at a position corresponding to the lower side of the inverter 2, and a breather 11 is detachably attached to this mounting hole 13 from the outside. The breather 11 is formed by integrally forming a cover body 11b at a distance from the outer end of a cylindrical portion 11a, and a plate-shaped filter 12 is attached to close the outer end of the cylindrical portion 11a. The breather 11 in this embodiment is made by injection molding a synthetic resin material, but the invention is not limited to this and may be made of, for example, aluminum die-cast.

[0031] A thick portion 14 that bulges into the housing 3 is formed in the outer wall 3a so as to surround the breather 11, and a cooling passage 15 that is continuous with the inner end of the cylindrical portion 11a of the breather 11 penetrates the thick portion 14. As a result, the inside of the housing 3 is communicated with the outside via the cooling passage 15, the inside of the cylindrical portion 11a of the breather 11, and the filter 12. Note that the cooling passage 15 in this embodiment has a circular cross section with the axis L coinciding with that of the cylindrical portion 11a of the breather 11, but the cross-sectional shapes of the cooling passage 15 and the cylindrical portion 11a are not limited to this and can be changed as desired.

[0032] A breather water passage 16 is formed in the thick portion 14, and one end of the breather water passage 16 is connected to the internal water passage 4a of the inverter water passage 4 located above. Specifically, one end of the breather water passage 16 branches downward from the internal water passage 4a to bypass the lower side of the breather 11, and the other end joins the internal water passage 4a from below. As a result, as shown in Figure 2, the breather water passage 16 and the cooling passage 15 are adjacent to each other across the partition wall 14a of the thick portion 14. Therefore, as will be described in detail later, the cooling water flowing through the breather water passage 16 cools the inner surface of the cooling passage 15 via the partition wall 14a, and ultimately the air flowing through the cooling passage 15, thereby preventing oil from adhering to the filter 12 due to oil smoke or oil mist.

[0033] Four plate-shaped fins 17 that face in a direction perpendicular to the axis L of the cooling passage 15 are integrally provided on the inner peripheral surface of the cooling passage 15 to protrude therefrom. More specifically, the fins 17 are arranged side by side at predetermined intervals along the axis L of the cooling passage 15, and although not shown, are also arranged at different angles around the axis L. Note that the number and arrangement of the fins 17 are not limited to this and can be changed as desired.

[0034] In addition, a flow control valve 18 is provided at the branch point between the internal water passage 4a and the breather water passage 16, and the cooling water flowing through the inverter water passage 4 is diverted to the breather water passage 16 side depending on the opening degree A of the flow control valve (from 0% fully closed to 100% fully open). Therefore, the amount of cooling water flowing through the breather water passage 16 can be increased or decreased depending on the opening degree A of the flow control valve 18, and the cooling capacity of the cooling water can be adjusted accordingly.

[0035] On the other hand, the amount of oily smoke and oil mist generated inside the housing 3 depends on the operating range of the motor 1. Figure 3 is a characteristic diagram of the motor 1 showing the operating range in which oily smoke and oil mist are generated. The amount of oily smoke generated depends primarily on the motor torque (motor load), and as the motor torque increases along with the load, the heat generated by the coils and other components becomes more pronounced, causing the temperature of the heated oil to rise and promoting the generation of oily smoke (this corresponds to the oily smoke generation region of the present invention, and is shown as regions E1 and E2 in Figure 3). For this reason, the state of oily smoke generation can be estimated using the oil temperature Toil, for example, as an index.

[0036] Furthermore, the amount of oil mist generated depends primarily on the rotational speed of the motor 1 (rotational speed of the rotor 1b), and as the rotational speed increases, oil scattering becomes more pronounced, promoting the generation of oil mist (this corresponds to the oil mist generation region of the present invention, and is shown as region E3 in Figure 3). For this reason, the state of oil mist generation can be estimated using, for example, vehicle speed V, which correlates with the rotational speed of the rotor 1b, as an index.

[0037] On the other hand, the more the opening degree A of the flow rate control valve 18 is increased, the more the amount of coolant flowing through the breather water passage 16 is increased, thereby improving the cooling capacity, but the load on the coolant pump 5 increases by the amount of the increase in the flow rate. Therefore, in order to reduce unnecessary power consumption of the driving battery, which is the power source for the coolant pump 5, it is necessary to avoid excessive flow of coolant through the breather water passage 16 and, ultimately, an unnecessary increase in the opening degree of the flow rate control valve 18.

[0038] Therefore, in this embodiment, in order to optimize the flow rate of the cooling water in the breather water passage 16, the controller 21 controls the opening degree A of the flow rate adjustment valve 18. The controller 21 includes an input / output device, a memory device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), a timer counter, etc. As shown in Fig. 1, various sensors such as an oil temperature sensor 22 that detects the oil temperature Toil inside the housing 3 and a rotation speed sensor 23 that detects the rotation speed of the rotor 1b are connected to the input side of the controller 21, and various devices such as a flow rate adjustment valve 18 are connected to the output side of the controller 21.

[0039] For example, the controller 21 calculates the state of charge (SOC) of the driving battery based on information such as the temperature and voltage of the driving battery and the current flowing between the driving battery and the inverter 2. The controller 21 also calculates the current vehicle speed V based on the rotational speed of the rotor 1b, and receives input information about the driving mode currently selected on the vehicle side (e.g., normal mode, sports mode, eco mode, etc.). The controller 21 then adjusts the opening A of the flow rate adjustment valve 18 in accordance with the input information and the determination results based on this information.

[0040] FIG. 4 is a flowchart showing a valve opening control routine executed by the controller 21. First, in step 1, controller 21 determines whether the SOC of the drive battery is 20% (SOC determination value) or higher, and then in step 2, determines whether eco mode (SOC preservation mode) is selected as the drive mode. If the determination in step 1 is No (negative), the drive battery has no SOC margin, and if the determination in step 2 is Yes (affirmative), it can be assumed that the vehicle is being driven in a manner that is suitable for saving drive battery power. That is, in either case, because the situation dictates that reducing drive battery power consumption should take priority over preventing clogging of filter 12 of breather 11, the process proceeds to step 3, where the opening degree A of flow control valve 18 is controlled to 0%, and the routine then ends.

[0041] Furthermore, if the determination in step 1 is Yes and the determination in step 2 is No, the routine proceeds to step 4, where it is determined whether the oil temperature Toil is 60°C or higher. If the determination is Yes, that is, if it is estimated that a large amount of oil smoke is being generated inside the housing 3 due to a rise in oil temperature, the routine proceeds to step 5, where the opening degree A of the flow control valve 18 is controlled to 100%, and then the routine ends.

[0042] If the determination in step 4 is No, the routine proceeds to step 6 to determine whether the oil temperature Toil is 40° C. or higher. If the determination is Yes, that is, if it is estimated that a considerable amount of oil smoke is being generated inside the housing 3, although not as much as in the case of 60° C. or higher, the routine proceeds to step 7 to control the opening A of the flow control valve 18 to 50%, and then ends the routine.

[0043] If the determination in step 6 is No, the process proceeds to step 8, where it is determined whether the vehicle speed V is 80 km / h or more. If the determination is Yes, that is, if it is estimated that although not much oil smoke is being generated, a large amount of oil mist is being generated due to oil being scattered by the rotor 1b rotating at high speed, the process proceeds to step 7. Furthermore, if neither the conditions of steps 6 nor 8 are met, i.e., if it is estimated that the amount of oil smoke and oil mist generated is small, the process proceeds to step 3, where the opening degree A of the flow control valve 18 is controlled to 0%, and then the routine is terminated.

[0044] The threshold values applied in the processes of steps 1, 4, 6, and 8 are merely examples and can be changed arbitrarily. When the motor 1 is operating in a high torque region near the upper limit (corresponding to region E1 in FIG. 3) due to the above-described control of the opening of the flow control valve 18 by the controller 21, the opening of the flow control valve 18 is controlled to A=100% in step 5 of FIG. 4. At this time, a large amount of oily smoke is generated within the housing 3 and mixed with the air, and the air expands in volume as its temperature rises and is discharged to the outside via the cooling passage 15, the cylindrical portion 11a of the breather 11, and the filter 12. Then, as the air flows through the cooling passage 15, it comes into contact with the inner circumferential surface of the cooling passage 15, whose temperature has been reduced by the cooling water in the breather water passage 16, and is cooled.

[0045] At this time, the air contains a large amount of oily smoke. However, the inner circumferential surface of the cooling passage 15 is sufficiently cooled by the large amount of cooling water flowing into the breather water passage 16 via the flow control valve 18, which has an opening A of 100%. In addition, the fins 17 increase the contact area between the inner circumferential surface of the cooling passage 15 and the air, and these factors combine to efficiently cool the air. Therefore, the oily smoke contained in the air is liquefied and separated before reaching the filter 12, and is returned from the cooling passage 15 to the housing 3. As a result, air containing almost no oily smoke flows through the filter 12, preventing clogging due to oil.

[0046] Furthermore, when the motor 1 is operating in a high torque range (corresponding to region E2 in Figure 3), although not at the upper limit, the flow control valve 18 is controlled to an opening of A = 50% in step 7 of Figure 4. At this time, oily smoke is generated inside the housing 3 and mixed into the air, but this air is cooled as it flows through the cooling passage 15, liquefying and separating the oily smoke. This makes it possible to prevent clogging of the filter 12 due to oil.

[0047] Also, in consideration of the fact that the amount of oily smoke generated is smaller compared to the case of the high torque range near the upper limit described above, the opening degree A of the flow control valve 18 is limited to 50%. Therefore, just the right amount of coolant flows through the breather water passage 16 to cool the air, preventing clogging of the filter 12 as described above, and reducing the load on the coolant pump 5 compared to when the opening degree A is 100%, thereby suppressing unnecessary power consumption from the driving battery.

[0048] Furthermore, even when the motor 1 is operating in a high rotational speed range (corresponding to region E3 in FIG. 3) with a relatively low torque, the flow control valve 18 is controlled to an opening A of 50% in step 7 of FIG. 4. At this time, a large amount of oil mist is generated inside the housing 3 and mixes with the air, but the air is cooled as it flows through the cooling passage 15, liquefying and separating the oil mist. This prevents clogging of the filter 12 due to oil. Additionally, by keeping the flow control valve 18 at an opening A of 50% in this case as well, unnecessary power consumption from the driving battery can be suppressed.

[0049] In this way, clogging of the filter 12 can be prevented in any operating range, and good filtering function can be maintained for a long period of time, reliably preventing the intrusion of foreign matter from the outside. This prevents malfunction of the motor 1 due to foreign matter and improves reliability. On the other hand, when the motor 1 is operating in the low-medium torque range and low-medium rotation range (corresponding to areas other than E1 to E3 in FIG. 3), the flow control valve 18 is controlled to an opening A of 0% in step 3 of FIG. 4. At this time, the amount of oil smoke or oil mist generated is small, so there is almost no possibility that these factors will clog the filter 12. Furthermore, by keeping the flow control valve 18 at an opening A of 0%, the flow of cooling water through the breather water passage 16 is stopped, which reduces the load on the cooling water pump 5 and reduces unnecessary power consumption from the driving battery.

[0050] Similarly, when the SOC of the traction battery is low and eco mode is selected as the driving mode, the flow rate control valve 18 is controlled to an opening A of 0% in step 3 of FIG. 4 . In either case, it can be considered that reducing power consumption from the traction battery is a priority. Even if oil smoke or oil mist is generated inside the housing 3, the filter 12 does not immediately become clogged. The SOC may recover before clogging occurs, or the vehicle may be switched to another driving mode, so no fatal problem occurs. Furthermore, by keeping the flow rate control valve 18 at an opening A of 0%, unnecessary power consumption from the traction battery is reduced. Therefore, when the SOC of the traction battery is low, the SOC can be preserved as much as possible. When eco mode is selected, the vehicle can continue to drive in a manner that is optimal for saving power, as intended by the driver.

[0051] On the other hand, in this embodiment, the cooling water from the existing inverter water passage 4 is diverted to the breather water passage 16 side, and the flow rate is adjusted according to the opening A of the flow control valve 18. Therefore, there is no need to provide a dedicated cooling water pump or radiator for the breather water passage 16, which contributes to reducing the manufacturing cost of the motor 1. Although the description of the embodiment has been completed above, aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the breather structure of the oil-cooled motor 1 mounted on an electric vehicle as an electric vehicle is embodied, but the present invention is not limited to this. For example, the present invention may be embodied in a breather structure of an oil-cooled motor mounted on a hybrid electric vehicle (HEV), or a breather structure of an oil-cooled motor mounted on a plug-in hybrid electric vehicle (PHEV) that can be externally charged or externally powered.

[0052] In the above embodiment, the cooling water from the inverter water passage 4 is diverted to the breather water passage 16 side, but the breather water passage 16 may be configured as an independent cooling circuit. In that case, a cooling water pump and a radiator are provided in the breather water passage 16, and the flow rate of the cooling water in the breather water passage 16 is adjusted according to the rotation speed of the cooling water pump. In this case, the cooling water pump functions as the flow rate adjuster of the present invention.

[0053] In the above embodiment, the opening degree A of the flow rate control valve 18 is controlled according to the operating range of the motor 1, but this is not limiting. For example, the flow rate control valve 18 may be omitted, and the cooling water from the inverter water passage 4 may be always circulated through the breather water passage 16. In the above embodiment, the opening degree A of the flow control valve 18 was controlled in accordance with the oil temperature Toil and the vehicle speed V as the operating range of the motor 1, but control may be performed based on only one of them. Also, since the temperature of the stator 1a, like the oil temperature Toil, is correlated with the amount of oily smoke generated, for example, as shown by the dashed line in Figure 1, the temperature of the stator 1a may be detected by a stator temperature sensor 31, and the processing of steps 4 and 6 in Figure 4 may be performed based on that information. [Explanation of symbols]

[0054] 1 Oil-cooled motor 2 inverters 3. Housing 4 Inverter Waterway 11 Breather 12 Filters 15 Cooling passage 16 Breather Canal 17 Finn 18 Flow control valve (flow control part) 21 Controller

Claims

1. An oil-cooled motor is installed in an electric vehicle as a power source for driving the vehicle and is cooled by circulating oil within the housing. a breather attached to the housing and communicating the inside of the housing with the outside via a filter; a cooling passage formed in the housing to communicate the inside of the housing with the filter; a breather water passage formed adjacent to the cooling passage and configured to allow cooling water to flow therethrough to cool an inner circumferential surface of the cooling passage; A breather structure for an oil-cooled motor, comprising:

2. A plurality of fins are provided on the inner peripheral surface of the cooling passage.

2. The breather structure for an oil-cooled motor according to claim 1.

3. a flow rate adjusting unit that adjusts the flow rate of cooling water in the breather water channel; a controller for controlling the flow rate adjusting unit; Furthermore, The controller controls the flow rate adjusting unit to increase the flow rate of cooling water in the breather water channel compared to other operating regions when the oil-cooled motor is operating in a preset oil smoke generation region.

2. The breather structure for an oil-cooled motor according to claim 1.

4. a flow rate adjusting unit that adjusts the flow rate of cooling water in the breather water channel; a controller for controlling the flow rate adjusting unit; Furthermore, The controller controls the flow rate adjusting unit to increase the flow rate of cooling water in the breather water passage when the oil-cooled motor is operating in a preset oil mist generation region compared to other operating regions.

2. The breather structure for an oil-cooled motor according to claim 1.

5. The oily smoke generating region is set in a high load region of the motor.

4. The breather structure for an oil-cooled motor according to claim 3.

6. The oil mist generation region is set in the high rotation range of the motor.

5. The breather structure for an oil-cooled motor according to claim 4.

7. The controller causes the flow rate adjusting unit to stop the flow of cooling water through the breather water passage when the SOC of the driving battery that is the power source of the motor is less than a preset SOC determination value, or when an SOC preservation mode that preserves the SOC of the driving battery is selected as the driving mode of the electric vehicle.

5. The breather structure for an oil-cooled motor according to claim 3 or 4.

8. The housing contains an inverter that drives and controls the motor, The inverter is cooled by cooling water circulating through an inverter water channel, The flow rate adjusting unit is a flow rate adjusting valve that diverts the cooling water flowing through the inverter water channel to the breather water channel according to the opening degree.

5. The breather structure for an oil-cooled motor according to claim 3 or 4.

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