Cooling system

Abstract

The invention provides a cooling system which is low in cost and high in cooling efficiency. The cooling system cools heating equipment in the electric vehicle. The cooling system is provided with a cooling liquid, a flow path for the cooling liquid, and a pump for circulating the cooling liquid in the flow path, the flow path is provided with a portion containing nitrile rubber on a flow path wall, the cooling liquid contains 95 mass% or more of mineral oil, and the aniline point of the cooling liquid is 80 DEG C to 105 DEG C.

Description

Technical Field

[0001] The present disclosure relates to cooling systems. Background Art

[0002] Various techniques have been proposed regarding the cooling system disclosed in Japanese Patent Application Laid-Open Nos. 2011-146320, 2021-068838, 2017-091801, 2016-190953, and 2011-252100.

[0003] The cooling system of the secondary battery (storage battery) requires the insulation of the coolant. In addition, in electric vehicles where cost competition is fierce, the cooling system is also required to be low-cost. Moreover, in electric vehicles that are densely equipped with heat-generating devices (secondary batteries, inverters, converters, generators, motors, etc.), a cooling system that can efficiently cool even if the flow path of the coolant is made thinner (reduced cross-sectional area) is required. In the coolant of the prior art, it is difficult to take into account both the cooling performance and the compatibility with low-cost nitrile rubber. Summary of the invention

[0004] The present disclosure provides a cooling system with low cost and high cooling efficiency.

[0005] That is, the present disclosure includes the following aspects.

[0006] A cooling system for cooling a heat generating device in an electric vehicle.

[0007] The cooling system includes a coolant, a flow path for the coolant, and a pump for circulating the coolant in the flow path.

[0008] The flow path has a portion containing nitrile rubber on the flow path wall,

[0009] The coolant contains 95% by mass or more of mineral oil, and the coolant has an aniline point of 80°C to 105°C.

[0010] The kinematic viscosity of the coolant at 40°C is 5 mm 2 / s or less.

[0011] The heat generating device is at least one selected from the group consisting of an inverter, a converter, a generator, a motor, and a battery.

[0012] The cooling liquid contains an additive, and the additive is at least one selected from the group consisting of a defoaming agent, an antioxidant, a rust inhibitor, a pour point depressant, a dispersant, a surfactant, and an anti-flow charging agent.

[0013] The cooling system of the present disclosure is low-cost and has high cooling efficiency. 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 parts, and in which:

[0015] Figure 1 This is a schematic diagram of a testing machine for evaluating the cooling performance of a coolant. DETAILED DESCRIPTION

[0016] The following describes the implementation of the present disclosure. It should be noted that matters other than those specifically mentioned in this specification and required for the implementation of the present disclosure (for example, the general structure and manufacturing process of the cooling system that do not represent the present disclosure) can be grasped as design matters by those skilled in the art based on the prior art in this field. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in this field.

[0017] In addition, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships.

[0018] In the present disclosure, a cooling system for cooling a heat generating device in an electric vehicle is provided.

[0019] The cooling system includes a coolant, a flow path of the coolant, and a pump that circulates the coolant in the flow path.

[0020] The flow path includes a portion containing nitrile rubber in a flow path wall.

[0021] The coolant contains 95% by mass or more of mineral oil, and an aniline point of the coolant is 80°C to 105°C.

[0022] Conventionally, the cooling component side is provided with an insulating structure, and a water-based coolant with low insulating properties is used as the coolant. However, by adding an insulating structure to the cooling component side, a material with poor heat transfer is sandwiched between the part to be cooled and the coolant, thereby reducing the cooling performance.

[0023] The commonly used water-based coolant (ethylene glycol-based) has low insulation properties. On the other hand, mineral oil, which has excellent insulation properties, also needs to consider compatibility with rubber materials used in hoses, etc.

[0024] As a criterion for determining rubber compatibility, the aniline point is a general item. If the aniline point is low, the rubber will generally swell more, so it is necessary to pay attention to leakage. On the other hand, if the aniline point is too high, the rubber will shrink, so there is also the possibility of leakage.

[0025] Conventionally, acrylic rubber, which has a relatively high operating temperature and is heat-resistant, is used in lubricating oil applications. Therefore, the rubber compatibility is defined as the aniline point of the compatibility with the acrylic rubber.

[0026] On the other hand, the present disclosure is limited to cooling applications such as batteries in electric vehicles, and the operating temperature is lower than before. Therefore, it is difficult to use rubber that has heat resistance like acrylic rubber but is expensive and has low oil resistance, and the use of nitrile rubber, which has higher oil resistance and is cheap, is a prerequisite. If the rubber type is different, the optimal aniline point of the corresponding oil side changes. Therefore, the aniline point suitable for nitrile rubber is specified in the present disclosure.

[0027] The present disclosure discloses a coolant (non-aqueous) having compatibility with nitrile rubber when applying a highly insulating coolant (non-aqueous) to heat generating devices of electric vehicles. The heat generating devices include batteries, inverters, converters, generators, motors, radiators, oil coolers, etc.

[0028] The cooling system of the present disclosure includes a coolant that can ensure airtightness of the coolant pipe even when low-cost nitrile rubber is used for the coolant pipe, and has a small pressure loss even when the coolant flow path has a small diameter.

[0029] By having the coolant disclosed in the present invention, the swelling property can be controlled even when nitrile rubber is used for the flow path piping, and as a result, the airtightness of the flow path piping can be ensured. At the same time, the kinematic viscosity of the coolant can be reduced, and the pressure loss can be reduced even in a cooling system where the heat generating device is highly dense and the cross-sectional area of ​​the coolant flow path is small. As a result, a cooling system with low cost and high cooling efficiency can be achieved.

[0030] The cooling system of the present disclosure cools heat-generating equipment in an electric vehicle.

[0031] An electric vehicle is a vehicle that travels by driving an electric motor.

[0032] Electric vehicles are equipped with cooling systems, heating equipment, etc.

[0033] Examples of heat generating devices include inverters, converters, generators, motors, batteries, radiators, oil coolers, etc. Among them, the heat generating device may be an inverter, converters, generators, motors, batteries, etc.

[0034] The heat generating device may also have a power card. The power card may also be in physical contact with the cooling liquid.

[0035] The type of storage battery (secondary battery) is not particularly limited, and examples thereof include nickel-hydrogen secondary batteries, lithium-ion secondary batteries, etc. The secondary battery may be a liquid secondary battery using an electrolytic solution as an electrolyte, or a solid secondary battery using a solid electrolyte as an electrolyte.

[0036] The cooling system includes a coolant, a flow path of the coolant, and a pump that circulates the coolant in the flow path.

[0037] The flow path only needs to have a portion containing nitrile rubber on the flow path wall. The flow path may also be composed of nitrile rubber.

[0038] The coolant contains 95% by mass or more of mineral oil, and the aniline point of the coolant is 80°C to 105°C.

[0039] The kinematic viscosity of the coolant at 40°C can be 5 mm 2 / s or less.

[0040] The coolant may contain additives.

[0041] Examples of the additives include defoamers, antioxidants, rust inhibitors, pour point depressants, dispersants, surfactants, and anti-flow static agents. The additives may contain one or more of these.

[0042] The coolant may contain 95% by mass or more of the mineral oil, or may contain 97% by mass or more of the mineral oil.

[0043] The coolant may contain 5% by mass or less of the additive, or may contain 3% by mass or less of the additive.

[0044] The mineral oil may include a first hydrocarbon and a second hydrocarbon. The first hydrocarbon includes at least one of cycloparaffinic hydrocarbons and aromatic hydrocarbons. The second hydrocarbon includes at least one of paraffinic hydrocarbons and olefinic hydrocarbons.

[0045] The mixing ratio of the second hydrocarbon may be higher than that of the first hydrocarbon. In order to improve the compatibility of nitrile rubber, the aniline point can be adjusted from 80°C to 105°C by reducing the ratio of cycloparaffinic and aromatic hydrocarbons that swell the rubber and increasing the ratio of paraffinic and olefinic hydrocarbons.

[0046] The parameters in the examples were measured and calculated by the following methods.

[0047] Aniline point

[0048] Aniline is placed in a beaker, and the same amount of the sample as the aniline is placed in the beaker. At this time, the ratio of aniline to sample is adjusted to 5:5. The solution containing the aniline and sample is cooled, and the temperature at the time of separation is defined as the aniline point.

[0049] Rubber compatibility

[0050] A sheet of nitrile rubber was immersed in a test sample at 100° C. for 200 hours. The rubber volume swelling ratio after the test was measured in accordance with JIS standard (K6258).

[0051] Kinematic viscosity at 40°C

[0052] The Ubbelohde viscometer was placed in a bath maintained at 40° C., and the kinematic viscosity of the measurement sample was measured in accordance with JIS standard (Z8803).

[0053] Flash Point

[0054] The flash point was measured by the Pensky-Martens closed method in accordance with JIS standard (K2265-3: 2007).

[0055] Pour Point

[0056] The pour point was measured according to JIS standard (K2269).

[0057] Cooling performance

[0058] Figure 1 This is a schematic diagram of a testing machine for evaluating the cooling performance of a coolant.

[0059] Determine the cooling performance Q of the sample w (W / K)Use Figure 1 The test machine shown was used for measurement using the following formula and evaluation conditions.

[0060] Evaluation conditions

[0061] Air volume of desktop electric fan: 4.5m / sec

[0062] Temperature difference: 40°C (outside air: 25°C, coolant: 65°C)

[0063] V w :Coolant flow rate (10L / min)

[0064] γ w : Density of coolant

[0065] C pw : Specific heat of coolant

[0066] t w1 : The temperature of the coolant upstream of the radiator

[0067] t w2 : The temperature of the coolant downstream of the radiator

[0068] (Mathematical formula 1)

[0069]

[0070] Examples 1 to 3, Comparative Examples 1 to 5

[0071] Coolants containing the components shown in Table 1 were prepared, and the performance of each coolant was evaluated. Table 1 shows the results.

[0072] Table 2 shows the physical properties of mineral oils 1 to 6 in Table 1.

[0073] (Table 1)

[0074]

[0075]

[0076] (Table 2)

[0077]

[0078]

[0079] In Comparative Example 5, a polar base such as ethyl octanoate observed in the prior art is used. In Comparative Example 5, there is no compatibility with nitrile rubber.

[0080] Furthermore, as shown in Comparative Examples 1 to 4, when the aniline point is outside the range specified in the present disclosure, the compatibility with the nitrile rubber tends to deviate from the preferred numerical value.

[0081] On the other hand, as shown in Examples 1 to 3, it can be seen that when the aniline point is within the specified range of the present disclosure, the compatibility of the nitrile rubber is within a preferred numerical range and desired cooling performance can be ensured.

Claims

1. A cooling system for cooling a heat generating device in an electric vehicle, wherein: The cooling system includes a coolant, a flow path of the coolant, and a pump that circulates the coolant in the flow path. The flow path has a portion containing nitrile rubber on the flow path wall, The coolant contains 95% by mass or more of mineral oil, and the coolant has an aniline point of 80°C to 105°C.

2. The cooling system according to claim 1, wherein: The kinematic viscosity of the coolant at 40°C is 5 mm 2 / s or less.

3. The cooling system according to claim 1, wherein: The heat generating device is at least one selected from the group consisting of an inverter, a converter, a generator, a motor, and a battery.

4. The cooling system according to claim 1, wherein: The coolant contains an additive, The additive is at least one selected from the group consisting of a defoaming agent, an antioxidant, a rust inhibitor, a pour point depressant, a dispersant, a surfactant, and an anti-flow charging agent.

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