Motor system

Abstract

The present invention addresses the problem of providing a motor system capable of reducing the possibility of poor insulation of a stator. A motor system includes a housing, a circulation path, a cooling mechanism, and a moisture removal mechanism. The housing accommodates a stator of the motor. The housing is filled with cooling oil to immerse the stator. The circulation path connects an outlet and an inlet provided in the housing, and circulates the cooling oil. The cooling mechanism is disposed midway along the circulation path and cools the circulating cooling oil. The moisture removal mechanism is disposed at a position partway along the circulation path downstream of the cooling position of the cooling mechanism or at the same position as the cooling position of the cooling mechanism, and removes moisture from the cooling oil cooled or cooled by the cooling mechanism.

Description

Technical Field

[0001] This invention relates to a motor system. Background Technology

[0002] In Patent Document 1, annular oil chambers are formed by sealing the two ends of the cylindrical stator of the motor with oil throughout the entire circumference. The oil chambers are connected to an oil cooler for supplying and recovering cooling oil. For example, by supplying cooling oil cooled from the oil cooler to the oil chambers, the stator and the like are directly cooled, thus improving cooling efficiency.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2010-178478 Summary of the Invention

[0004] In the technology described in Patent Document 1, there is a problem that when water enters the cooling oil, the water adheres to the stator, which may cause poor insulation of the stator.

[0005] The object of the present invention is to provide a motor system that can reduce the possibility of stator insulation failure in view of such problems.

[0006] The motor system of the present invention comprises: a housing that houses the stator of the motor and is filled with cooling oil to immerse the stator; a circulation path that connects an outlet and an inlet disposed on the housing to circulate the cooling oil; a cooling mechanism disposed midway through the circulation path to cool the cooling oil circulating in the circulation path; and a moisture removal mechanism disposed midway through the circulation path at a position downstream of or at the same position as the cooling position of the cooling mechanism to remove moisture from the cooling oil being cooled or being cooled by the cooling mechanism.

[0007] The above structure reduces the likelihood of insulation failure in the stator by removing moisture from the cooling oil and inhibiting moisture adhesion to the stator.

[0008] In a motor system according to another aspect of the invention, the moisture removal mechanism comprises: a storage tank that temporarily stores a certain amount of cooling oil circulating in the circulation path and is further filled with a gas capable of receiving water vapor evaporated from the stored cooling oil; and a pressure relief valve capable of exchanging the gas filled in the storage tank with gas outside the storage tank according to the internal pressure of the storage tank.

[0009] The above structure enables the effective removal of moisture from the cooling oil.

[0010] In another aspect of the motor system of the invention, the moisture removal mechanism further comprises: a membrane arranged to surround a hollow portion of the tank and allowing only water vapor to pass through, the membrane being positioned above the level of the cooling oil stored in the tank.

[0011] The above structure enables more effective removal of moisture from the cooling oil.

[0012] Invention Effects

[0013] This invention provides a motor system that can reduce the possibility of stator insulation failure. Attached Figure Description

[0014] Figure 1 This is a diagram illustrating an example of the structure of the motor system 100 according to the first embodiment.

[0015] Figure 2 This is a diagram showing an example of the structure and configuration of the moisture removal mechanism 5 of the motor system 100 according to the first embodiment.

[0016] Figure 3 It is a graph showing the relationship between temperature and the saturated moisture absorption of cooling oil.

[0017] Figure 4 This is a diagram showing the structure of the motor system R1 involved in the first comparative example and the motor system R2 involved in the second comparative example.

[0018] Figure 5 This is a graph showing the results of a verification experiment on whether there are water droplets in the cooling oil after cooling to 25°C in the motor system 100 according to the first embodiment.

[0019] Figure 6 This is a graph showing the results of a verification experiment on the insulation breakdown voltage of the cooling oil in the motor system 100 according to the first embodiment after cooling at 25°C. Detailed Implementation

[0020] Hereinafter, specific embodiments of the invention will be described in detail with reference to the accompanying drawings. In the drawings, the same elements are labeled with the same symbols, and repeated descriptions are omitted as needed for clarity.

[0021] (First Embodiment)

[0022] First, use Figure 1 The structure of the motor system 100 according to the first embodiment will be described.

[0023] Figure 1 This is a diagram illustrating an example of the structure of the motor system 100 according to the first embodiment. (See diagram below.) Figure 1 As shown, the motor system 100 includes a motor 1, a housing 2, a circulation path 3, a cooling mechanism 4, a moisture removal mechanism 5, a TA housing 6, and a pressure relief valve 7.

[0024] Motor 1 has a stator 11 and a rotor 12.

[0025] The housing 2 houses the stator 11 and rotor 12 of the motor 1. The housing 2 is filled with cooling oil to submerge the stator 11 and rotor 12 of the motor 1 (i.e., to fill the space between the housing 2, the stator 11, and the rotor 12). The cooling oil is oil used to cool the stator 11. For example, the cooling oil has the function of absorbing the heat generated from the stator 11 and preventing the stator 11 from overheating.

[0026] The circulation path 3 is a path that connects the outlet 21 and the inlet 22 provided on the housing 2 and circulates the cooling oil from the outlet 21 to the inlet 22. In addition, the circulation of the cooling oil is carried out by a pump (not shown).

[0027] Cooling mechanism 4 is positioned midway through circulation path 3. Cooling mechanism 4 cools the cooling oil in circulation path 3. Cooling mechanism 4 is, for example, a radiator or a water jacket.

[0028] The moisture removal mechanism 5 is located midway through the circulation path 3, either downstream of or at the same location as the cooling position of the cooling mechanism 4. The moisture removal mechanism 5 removes moisture from the cooling oil that has been cooled or is being cooled by the cooling mechanism 4.

[0029] The transmission actuator (TA) housing 6 is the housing that houses housing 2.

[0030] The pressure relief valve 7 is used to regulate the internal pressure of the TA housing 6.

[0031] Next, use Figure 2 Hereinafter, an example of the structure and configuration of the moisture removal mechanism 5 of the motor system 100 according to the first embodiment will be described.

[0032] Figure 2 This is a diagram showing an example of the structure and configuration of the moisture removal mechanism 5 of the motor system 100 according to the first embodiment.

[0033] <Structural Example of Moisture Removal Mechanism 5>

[0034] Figure 2 (A) is a diagram showing a first structural example of the moisture removal mechanism 5. Additionally, Figure 1 (The above) also represents the first structural example. For example... Figure 2 As shown in (A), the moisture removal mechanism 5 includes a storage tank 51 and a pressure relief valve 52.

[0035] The storage tank 51 temporarily stores a certain amount of cooling oil circulating in the circulation path 3. The inlet (In) of the storage tank 51 is connected to the outlet 21 of the shell 2 via the circulation path 3. Thus, cooling oil discharged from the outlet 21 of the shell 2 flows into the interior of the storage tank 51. Furthermore, the outlet (Out) of the storage tank 51 is connected to the inlet 22 of the shell 2 via the circulation path 3. Thus, the cooling oil inside the storage tank 51 is discharged from the storage tank 51 towards the inlet 22 of the shell 2.

[0036] Furthermore, the interior of the storage tank 51 is filled with a gas capable of receiving water vapor evaporated from the stored cooling oil. The gas is, for example, air. In doing so, the motor system 100 is able to remove moisture from the cooling oil circulating in the circulation path 3. Additionally, the gas is not limited to air; any gas capable of receiving water vapor evaporated from the stored cooling oil, such as argon, can be used.

[0037] Furthermore, the outlet of storage tank 51 is preferably located below the liquid level of the stored cooling oil. This prevents gas from flowing into the cooling oil discharged from storage tank 51. There are no restrictions on the location of the inlet of storage tank 51.

[0038] The pressure relief valve 52 is a valve that allows the gas stored inside the storage tank 51 to exchange with the gas outside the storage tank 51 based on the internal pressure of the storage tank 51. Through gas exchange, the motor system 100 can prevent the inability to receive water vapor evaporating from the cooling oil containing the gas.

[0039] on the other hand, Figure 2 (B) is a diagram showing a second structural example of the moisture removal mechanism 5. (See diagram for example.) Figure 2 As shown in (B), the moisture removal mechanism 5 includes a storage tank 51 and a pressure relief valve 52, as well as a membrane 53.

[0040] Membrane 53 is a membrane that allows only water vapor to pass through. Membrane 53 is arranged to surround the hollow portion of storage tank 51. For example, the outer periphery of membrane 53 is arranged along the inner wall of storage tank 51. Membrane 53 is positioned above the liquid level of the cooling oil stored in storage tank 51. Alternatively, the outer periphery of membrane 53 may not be arranged along the inner wall of storage tank 51, but may float on the liquid surface of cooling oil in a manner that surrounds the liquid surface of cooling oil stored in storage tank 51.

[0041] <Example of the configuration of moisture removal mechanism 5>

[0042] Figure 2 (C) is a diagram showing a first configuration example of the moisture removal mechanism 5. Figure 2In (C), the cooling mechanism 4 uses a radiator 4a. The moisture removal mechanism 5 is located further downstream of the cooling position of the radiator 4a. In this case, the moisture removal mechanism 5 removes moisture from the cooling oil cooled by the cooling mechanism 4.

[0043] on the other hand, Figure 2 (D) is a diagram showing a second configuration example of the moisture removal mechanism 5. Figure 2 In (D), the cooling mechanism 4 uses a water jacket 4b. The moisture removal mechanism 5 is positioned at the same location as the cooling position of the water jacket 4b. In this case, the moisture removal mechanism 5 removes moisture from the cooling oil cooled by the cooling mechanism 4.

[0044] Figure 3 This is a graph showing the relationship between temperature and the saturated moisture absorption capacity of cooling oil. For example... Figure 3 As shown, the saturated moisture absorption capacity of cooling oil is high at high temperatures and low at low temperatures. If cooling oil that has absorbed water at high temperatures is cooled, moisture exceeding the saturated moisture absorption capacity will be released from the cooling oil. For example, when water is absorbed at 80°C and cooled to 40°C, 500 ppm of water will be released from the cooling oil. Therefore, in order to effectively remove moisture from the cooling oil, it is necessary to remove moisture either after the cooling oil has cooled or during the cooling process. In this embodiment, after the cooling oil is heated by the stator 11, at the time after the cooling oil has cooled ( Figure 2 (as shown in (C)) or during the cooling process ( Figure 2 (D) shows the method for removing water from cooling oil, which can effectively remove water from cooling oil.

[0045] Next, use Figures 4-6 The comparison results of the motor system 100 according to the first embodiment, the motor system R1 according to the first comparative example, and the motor system R2 according to the second comparative example will be explained.

[0046] Figure 4 This is a diagram showing the structure of the motor system R1 involved in the first comparative example and the motor system R2 involved in the second comparative example.

[0047] Figure 4 (A) indicates the structure of the motor system R1 involved in the first comparative example. The motor system R1 is a system that uses a cooling method to cool the stator by dripping cooling oil onto the stator of the motor.

[0048] on the other hand, Figure 4(B) shows the structure of the motor system R2 according to the second comparative example. Motor system R2 is a system that employs a cooling method by immersing the stator in cooling oil to cool the stator. Here, motor system R2 also uses the stator cooling method disclosed in Patent Document 1. Furthermore, the cooling method of immersing the stator in cooling oil to cool the stator is also employed in the motor system 100 according to the first embodiment. By employing this cooling method, motor system R2 achieves a higher stator cooling efficiency than motor system R1.

[0049] Table 1 below shows the comparison results of motor system 100, motor system R1, and motor system R2. The items being compared are "cooling method", "cooling efficiency", "water absorption of cooling oil at 85°C and 85%", "presence or absence of water removal mechanism", "presence or absence of water droplets in cooling oil after cooling at 25°C", "insulation breakdown voltage of cooling oil after cooling at 25°C", and "insulation reliability".

[0050] [Table 1]

[0051]

[0052] The following is a supplement to Table 1.

[0053] (※1) The water absorption of the cooling oil at 85℃ and 85% RH was calculated as follows. Assuming the maximum water absorption under actual operating conditions, the water content of the cooling oil after exposure for 6 hours at 85℃ and 85% RH was determined. Figure 3 As shown, the saturated moisture absorption at 85℃ is 660ppm.

[0054] (※2) "Whether there are water droplets in the cooling oil after cooling at 25℃" is determined as follows. Figure 5 This is a graph showing the results of a verification experiment on the presence or absence of water droplets in the cooling oil after cooling to 25°C in the motor system 100 according to the first embodiment. (See figure) Figure 5 As shown, after absorbing moisture at 85°C and 85%RH, the cooling oil was cooled to 25°C, and the presence of water droplets in the cooling oil was visually confirmed. Here, as a sample corresponding to the motor system 100 of the first embodiment, a sample with the cooling oil sealed in a container that allows water vapor to pass through only one side was prepared (the sample with the container open in this figure). Furthermore, as a sample corresponding to the motor system R2 of the second comparative example, a sample with the cooling oil sealed in a container that does not allow water vapor to pass through was prepared (the sample with the container closed in this figure). Moreover, as shown in this figure, in the sample with the container open, it was confirmed that no water droplets were present in the cooling oil after cooling to 25°C. On the other hand, in the sample with the container closed, water droplets were confirmed in the cooling oil after cooling to 25°C.

[0055] (※3) The insulation breakdown voltage of the cooling oil after cooling at 25℃ is calculated as follows. Figure 6 This is a graph showing the results of a verification experiment on the insulation breakdown voltage of the cooling oil in the motor system 100 according to the first embodiment after cooling to 25°C. (See figure) Figure 6 As shown in (A), the electrodes were inserted into cooling oil cooled to 25°C, with the electrode spacing set to 0.5 mm. Furthermore, the insulation breakdown voltage (insulation breakdown voltage) was measured by applying a maximum voltage of 5 kV using a withstand voltage tester. Here, as... Figure 6 As shown in (B), in the absence of water droplets between the electrodes, even with an applied voltage of 5kV, insulation breakdown will not occur. On the other hand, as... Figure 6 As shown in (C), insulation breakdown occurred at 1.5 kV when water droplets were present between the electrodes. This is because if water droplets are present at the location where the electric field is applied, the insulation distance is insufficient, and the insulation breakdown voltage decreases.

[0056] (※4) "Insulation reliability" is calculated as follows. If the insulation design value (rated voltage × 2 + 1kV) is 2.3kV or higher, it is considered to have high "insulation reliability". For example, the rated voltage is set to 650V.

[0057] As described above, in the motor system 100, the stator 11 is cooled by immersing it in cooling oil, thus increasing the cooling efficiency of the stator 11. In the motor system 100, the water removal mechanism 5 removes water droplets from the cooling oil after cooling from 85°C to 25°C. Because water droplets are removed from the cooling oil after cooling to 25°C, the cooling oil at 25°C has a high insulation breakdown voltage and high insulation reliability. Therefore, the motor system 100 reduces the possibility of insulation failure in the stator 11.

[0058] Furthermore, the present invention is not limited to the above-described embodiments, and appropriate modifications can be made without departing from its spirit.

[0059] Symbol Explanation

[0060] 1-Motor, 2-Housing, 3-Circulation path, 4-Cooling mechanism, 4a-Radiator, 4b-Water jacket, 5-Moisture removal mechanism, 6-TA housing, 7-Pressure relief valve, 11-Stator, 12-Rotor, 21-Outlet, 22-Inlet, 51-Storage tank, 52-Pressure relief valve, 53-Membrane, 100-Motor system.

Claims

1. A motor system, characterized in that, have: A housing that houses the stator of the motor and is filled with cooling oil to immerse the stator; A circulation path, which connects the outlet and inlet provided on the housing, allows the cooling oil to circulate; A cooling mechanism, disposed midway through the circulation path, cools the cooling oil circulating in the circulation path; and A moisture removal mechanism is disposed in the middle of the circulation path, at a position downstream of or at the same position as the cooling position of the cooling mechanism, to remove moisture from the cooling oil being cooled or being cooled by the cooling mechanism.

2. The motor system according to claim 1, characterized in that, The moisture removal mechanism includes: A storage tank that temporarily stores a certain amount of cooling oil circulating in the circulation path, and is further filled with a gas capable of receiving water vapor evaporated from the stored cooling oil; and A pressure relief valve is used to exchange the gas filling the storage tank with the gas outside the storage tank, based on the internal pressure of the storage tank.

3. The motor system according to claim 2, characterized in that, The moisture removal mechanism further comprises: a membrane configured to surround a hollow portion of the storage tank, allowing only water vapor to permeate. The membrane is positioned above the level of the cooling oil stored in the tank.

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