Cooling system

Abstract

To provide a cooling system that is reduced in a risk of contamination of water into a circuit for an insulating cooling liquid composition.SOLUTION: A cooling system includes: an insulating cooling liquid composition; a circuit through which the cooling liquid composition circulates; an inlet for communicating the circuit to the outer space; and a fluorine resin filter for covering the inlet. A speed of the cooling liquid composition of 25°C passing through the filter exceeds 1 mL s-1. A speed of water of 25°C passing through the filter is equal to or less than 8×10-5 mL s-1.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cooling system. [Background technology]

[0002] BACKGROUND ART Automobiles equipped with a traction motor, such as hybrid vehicles, fuel cell vehicles, and electric vehicles, are equipped with heat-generating devices such as a motor, generator, inverter, converter, and battery, as well as a cooling system for cooling the heat-generating devices.

[0003] Cooling systems use coolant. If the coolant leaks due to an accident, it may come into contact with the terminals of the heat-generating device, causing a short circuit and potentially leading to a secondary disaster. To reduce the risk of secondary disasters, it is desirable for the coolant to have high insulating properties. Furthermore, by physically contacting the heat-generating device with insulating coolant (for example, by immersing the heat-generating device in the coolant), these devices can be cooled with high efficiency.

[0004] Patent Document 1 describes a cooling system having an electrically insulating coolant. Patent Document 2 describes a cooling device in which a water removal filter is provided in a circulation path of the coolant. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 137703 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-050624 Summary of the Invention [Problem to be solved by the invention]

[0006] The coolant in a cooling system needs to be replaced at the appropriate time. When replacing the coolant, there is a risk that an operator may accidentally pour an inappropriate liquid, such as water or a water-based coolant, into the cooling system. If water gets into a cooling system that uses an insulating coolant, the insulating properties of the coolant may be impaired. The filter installed in the cooling device described in Patent Document 2 can only remove small amounts of water, and cannot remove large amounts of water that have been accidentally added.

[0007] Therefore, the present disclosure provides a cooling system in which the risk of water being mixed into the circulation path of the insulating coolant composition is reduced. [Means for solving the problem]

[0008] Aspects of the present disclosure include, for example, the following aspects. [Section 1] 1. A cooling system comprising: an insulating coolant composition; a circulation path through which the coolant composition circulates; an inlet that connects the circulation path to an external space; a filter made of a fluorine-based resin that covers the injection port; Equipped with The rate at which the coolant composition at 25°C passes through the filter is 1 mL s -1 Super, The rate at which water at 25°C passes through the filter is 8 x 10 -5 mL s -1 Below is the cooling system. [Section 2] Item 2. The cooling system according to item 1, wherein the ratio of the average pore size to the thickness of the filter is within a range of 0.039 to 0.1. [Section 3] The rate at which the coolant composition at 25°C passes through the filter is 30 mL·s -1 Item 1 or 2. The cooling system according to item 1 or 2, wherein the cooling system is greater than 1000 kJ / s. [Section 4] Item 4. The cooling system according to any one of Items 1 to 3, wherein the filter is made of PTFE, and the coolant composition contains paraffinic mineral oil, naphthenic mineral oil, or a mixture thereof. [Effects of the Invention]

[0009] The cooling system of the present invention has a low risk of water being mixed into the circuit of the insulating coolant composition. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described. In this application, numerical ranges expressed using the symbol "to" include the numerical values ​​before and after the symbol "to" as the lower and upper limits, respectively. The upper and lower limit values ​​of numerical ranges described in this application can be used alone or in any combination to define preferred ranges. In this application, "comprising" and "containing" mean that additional components may be included, and encompass "consisting essentially of" and "consisting of." "Consisting essentially of" means that additional components may be included that do not have a substantial adverse effect. "Consisting of" means that only the materials listed are included, but does not exclude the inclusion of unavoidable impurities.

[0011] A cooling system according to an embodiment includes an insulating coolant composition, a circulation path through which the coolant composition circulates, an inlet that connects the circulation path to an external space, and a filter that covers the inlet.

[0012] The coolant composition contains an insulating base. The insulating base is preferably a hydrocarbon oil, an ester oil, or a mixture thereof. Examples of hydrocarbon oils include mineral oil, hydrocarbon synthetic oil, and mixtures thereof. Examples of mineral oils include paraffinic mineral oil, naphthenic mineral oil, and mixtures thereof. The content of the insulating base in the coolant composition is, for example, 10 to 100 mass%, preferably 30 to 99 mass%, more preferably 50 to 99 mass%, and even more preferably 70 to 99 mass%.

[0013] The coolant composition may further contain additives such as flame retardants, antioxidants, rust inhibitors, friction modifiers, anticorrosion agents, viscosity index improvers, pour point depressants, dispersants, surfactants, antiwear agents, solid lubricants, etc. The content of the additives in the coolant composition is, for example, 0.1 to 20 mass%, preferably 0.2 to 10 mass%, more preferably 0.4 to 5 mass%, and even more preferably 0.5 to 1 mass%.

[0014] The coolant composition is substantially free of water. In this specification, "substantially free of water" means that the coolant composition does not contain water in an amount that would reduce the insulating properties of the coolant composition to such an extent that it may short-circuit the cooled device, and preferably means that the water content in the coolant composition is 1.0 mass% or less, more preferably means that the water content in the coolant composition is 0.5 mass% or less, even more preferably means that the water content in the coolant composition is 0.1 mass% or less, and particularly preferably means that the water content in the coolant composition is 0 mass% (undetectable).

[0015] The conductivity of the coolant composition at 20° C. is, for example, 0.1 μS / cm or less, preferably 0.01 μS / cm or less, and more preferably 0.001 μS / cm or less.

[0016] The kinematic viscosity of the coolant composition at 20°C is, for example, 0.1 to 100 mm 2 / s, preferably 0.1 to 10 mm 2 / s.

[0017] The circulation path through which the coolant composition circulates may include, for example, piping, a reserve tank, one or more circulation units for circulating the coolant composition, one or more heat dissipation units for lowering the temperature of the coolant composition, and one or more heat absorption units for absorbing heat from a heat-generating device into the coolant composition. Examples of circulation units include electric pumps. Examples of heat dissipation units include radiators, chillers, and oil coolers. Examples of heat-generating devices include motors, generators, inverters, converters, and batteries. The heat-generating device may be partially or completely immersed in the coolant composition.

[0018] In one embodiment of the cooling system, the coolant composition is pumped up from a reserve tank by an electric pump, absorbs heat from a heat-generating device in a heat absorption unit, then dissipates heat in a downstream heat dissipation unit, and returns to the reserve tank.

[0019] The circulation path communicates with the external space through an inlet. For example, a reserve tank may communicate with the external space through the inlet. The inlet is covered with a filter. Therefore, the circulation path communicates with the external space through the filter. When the coolant composition is supplied to the inlet, the coolant composition passes through the filter and fills the circulation path. This allows the coolant composition to be supplied or replenished to the cooling system. The inlet may be openable and closable with a cap or the like.

[0020] The filter is made of fluororesin, examples of which include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and ethylene chlorotrifluoroethylene copolymer (ECTFE).

[0021] In one embodiment, the filter is made of PTFE and the coolant composition contains paraffinic mineral oil, naphthenic mineral oil, or a mixture thereof.

[0022] The rate at which the coolant composition at 25°C passes through the filter (permeation rate) is 1 mL s -1 The filter speed is preferably greater than 30 mL s. This allows an operator to visually check the drop in the liquid level of the coolant composition in the funnel when filling the circulation path with the coolant composition by pouring the coolant composition into the funnel connected to the inlet. This helps to ensure that a sufficient amount of coolant composition is filled into the circulation path. The rate at which the coolant composition at 25°C passes through the filter is preferably 30 mL s -1 This allows the operator to complete the filling of the coolant composition with a sufficiently short waiting time.

[0023] The rate at which water at 25°C passes through the filter is 8 x 10 -5 mL s -1 Such a filter requires more than 10 minutes for a single drop of water (approximately 0.05 mL) to pass through, preventing water from entering the circuit even if an operator accidentally tries to add water or water-based coolant to the cooling system.

[0024] The ratio of the average pore size to the thickness of the filter is preferably within a range of 0.039 to 0.1, more preferably 0.08 to 0.12. The average pore size of the filter is preferably 2 to 100 μm, more preferably 5 to 50 μm, even more preferably 8 to 40 μm, and even more preferably 30 to 40 μm. The average pore size of the filter is measured by the bubble point method (ASTM F316-86, JIS K 3832) using a perm porometer. The thickness of the filter is preferably 50 to 1000 μm, more preferably 100 to 800 μm, and even more preferably 200 to 600 μm. The rate at which the coolant composition at 25°C passes through the filter is preferably 0.076 mL cm per unit effective filtration area of ​​the filter. -2 ·s -1 More than 2.2 mL cm -2 ·s -1 Such filters are suitable for a typical opening area of ​​the inlet (e.g., 5 to 20 cm). 2), the above-mentioned permeation rates of the coolant composition and water can be achieved.

[0025] The cooling system according to the embodiment can be incorporated into an automobile equipped with a traction motor. In this specification, the term "automobile equipped with a traction motor" includes electric vehicles and fuel cell vehicles that do not have an engine and are equipped only with a traction motor as a power source, as well as hybrid vehicles that are equipped with both a traction motor and an engine as power sources.

[0026] The present invention is not limited to the above-described embodiments, and various modifications, additions, and deletions can be made without departing from the technical idea or scope of the present invention as defined in the claims. [Example]

[0027] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0028] A PTFE filter was prepared having the average pore size and thickness shown in Table 1. The average pore size of the filter was measured by the bubble point method (ASTM F316-86, JIS K 3832) using a perm porometer.

[0029] A cylindrical funnel with an inner diameter of 6 cm was connected to the collection bottle via a filter. The effective filtration area of ​​the filter was 13.2 cm. 2 It was.

[0030] At room temperature (25°C), 220 mL of coolant composition was poured into the funnel. Mineral oil was used as the coolant composition. The time it took for the entire amount of coolant composition to pass through the filter was measured. Based on the measured value, the rate at which the coolant composition passed through the filter (permeation rate) was calculated. The results are shown in Table 1.

[0031] At room temperature (25°C), 220 mL of water or ethylene glycol-based long-life coolant (LLC) (Toyota genuine Super Long-Life Coolant) was poured into the funnel. After 10 minutes, it was confirmed whether water or LLC had passed through the filter. The results are shown in Table 1.

[0032] [Table 1]

[0033] In Examples 1 to 4, the ratio of the average pore size to the thickness of the filter was within the range of 0.0392 to 0.1. The average pore size of the filter was 40 μm or less. In Examples 1 to 4, the coolant composition was -1 Ultra-high (0.076 mL cm per effective filtration area) -2 ·s -1 In Example 4, where the ratio of the average pore size to the thickness of the filter was 0.1, the coolant composition passed through the filter at a sufficiently high rate of 50 mL s -1 (3.79 mL cm per unit effective filtration area) -2 ·s -1 ) passed through the filter at a particularly high rate. In Comparative Examples 1 and 2, water and LLC did not pass through the filter, but the permeation rate of the coolant composition was low. In Comparative Example 3, the permeation rate of the coolant composition was high, but it was confirmed that water passed through the filter. Note that there is a high correlation (R 2 =0.93).

Claims

1. 1. A cooling system comprising: an insulating coolant composition; a circulation path through which the coolant composition circulates; an inlet that connects the circulation path to an external space; a filter made of a fluorine-based resin that covers the injection port; Equipped with the circulation path communicates with the external space via the filter; The rate at which the coolant composition at 25°C passes through the filter is 1 mL s －１ Super, The rate at which water at 25°C passes through the filter is 8 x 10 －５ mL・s －１ Below is the cooling system.

2. The cooling system of claim 1 , wherein the filter has an average pore size to thickness ratio in the range of 0.039 to 0.

1.

3. The rate at which the coolant composition at 25°C passes through the filter is 30 mL s －１ The cooling system of claim 1 , wherein the temperature is greater than 1000 K.

4. The cooling system of claim 1 , wherein the filter is made of PTFE and the coolant composition contains mineral oil.

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