JP7287260B2 - cooling system - Google Patents

Description

The present invention relates to cooling systems.

Patent Document 1 discloses a cooling system that cools an object to be cooled through which electricity flows with an electrically insulating cooling liquid. In the cooling system of Patent Document 1, the object to be cooled is immersed in the cooling liquid, and the cooling object is directly cooled by the cooling liquid. In another cooling system, an object to be cooled is indirectly cooled with a coolant through a heat transfer member. In these cooling systems, a silicone oil or a fluorine-based inert liquid is used as the cooling liquid.

JP 2018-125363 A

The conventional electrically insulating cooling liquids described above have low heat transfer properties. For this reason, when cooling an object to be cooled directly with the cooling liquid, it is necessary to increase the size of the pump that supplies the cooling liquid and the size of the radiator that releases the heat of the cooling liquid so that the cooling object is sufficiently cooled. was necessary. This is because the increase in the size of the pump increases the flow rate of the cooling liquid, which increases the amount of heat input from the object to be cooled to the cooling liquid. Also, the larger the radiator, the greater the amount of heat released from the cooling liquid.

In addition, when the object to be cooled is indirectly cooled with a cooling liquid, it is necessary to increase the size of the cooler including the heat transfer member and the size of the radiator so that the object to be cooled is sufficiently cooled. This is because the increase in the size of the cooler and radiator increases the amount of heat input from the object to be cooled to the cooling liquid and the amount of heat radiation from the cooling liquid.

As described above, in the conventional cooling system, it was necessary to increase the size of the components constituting the cooling system. As a result, the entire cooling system has become large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling system capable of downsizing the entire system.

In order to achieve the above object, according to the invention of claim 1,
A cooling system for cooling a cooling object (2) through which electricity flows,
a coolant (12) for cooling an object to be cooled;
A radiator (18) for releasing heat of the cooling liquid,
The coolant contains a liquid base material containing water and an orthosilicate that is compatible with the base material, and has electrical insulation.

According to this, since the coolant contains the orthosilicate, the coolant has a rust-preventing function. Therefore, compared with a coolant containing an ionic rust inhibitor for rust prevention, the coolant can contain less ionic rust inhibitor. That is, the electrical conductivity of the cooling liquid can be lowered compared to the cooling liquid containing an ionic rust inhibitor for rust prevention. This allows the cooling liquid to have electrical insulation.

In addition, the base of this coolant includes water, which has a higher thermal conductivity than the conventional coolants described above. Therefore, the heat transfer property of this cooling liquid can be made higher than that of the above-described conventional cooling liquid. By using a coolant with higher heat transfer than conventional coolants, it is possible to reduce the size of the components of the cooling system compared to conventional cooling systems. Therefore, it is possible to reduce the size of the cooling system as a whole.

Further, in order to achieve the above object, according to the invention described in claim 2,
A cooling system that cools objects through which electricity flows is
a coolant (12) for cooling an object to be cooled;
A radiator (18) for releasing heat of the cooling liquid,
The coolant contains a liquid base material containing water and an orthosilicate that is compatible with the base material, and does not contain an ionic rust inhibitor.

According to this, since the coolant contains the orthosilicate, the coolant has a rust-preventing function. Therefore, the coolant does not have to contain an ionic rust inhibitor. Since it does not contain an ionic rust inhibitor, this coolant has a lower electrical conductivity and a higher electrical insulation than when it contains an ionic rust inhibitor.

In addition, the base of this coolant includes water, which has a higher thermal conductivity than the conventional coolants described above. Therefore, the heat transfer property of this cooling liquid can be made higher than that of the above-described conventional cooling liquid. By using a coolant with higher heat transfer than conventional coolants, it is possible to reduce the size of the components of the cooling system compared to conventional cooling systems. Therefore, it is possible to reduce the size of the cooling system as a whole.

It should be noted that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and specific components etc. described in the embodiments described later.

It is a mimetic diagram showing the whole cooling system composition in a 1st embodiment. It is a sectional view of a cooler in a 1st embodiment. It is a sectional view of a cooler in a 2nd embodiment. FIG. 11 is a cross-sectional view of a conductive member in a third embodiment;

An embodiment of the present invention will be described below with reference to the drawings. In addition, in each of the following embodiments, portions that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A cooling system 10 shown in FIG. 1 is mounted on an electric vehicle. An electric vehicle obtains a driving force for running the vehicle from an electric motor for running. Electric vehicles include electric vehicles, plug-in hybrid vehicles, and electric two-wheeled vehicles. The number of wheels of the electric vehicle and the application of the vehicle are not limited. The electric vehicle is equipped with an electric motor for traveling as in-vehicle equipment, a battery 2, an inverter, and the like.

The electric motor for running is a motor generator that converts the electric power supplied from the battery 2 into power for running the vehicle, and also converts the power of the vehicle into electric power during deceleration. An electric motor for traveling generates heat as power is converted into electric power.

The battery 2 is a vehicle running battery that supplies electric power to a running electric motor. The battery 2 is charged with electric power supplied from the electric motor for traveling when the vehicle decelerates. The battery 2 can be charged with electric power supplied from an external power supply (that is, a commercial power supply) when the vehicle is stopped. The battery 2 generates heat as it is charged and discharged.

The inverter is a power conversion device that converts the power supplied from the battery 2 to the electric motor for traveling from direct current to alternating current. Further, the inverter converts the electric power charged from the electric motor for traveling to the battery 2 from alternating current to direct current. The inverter generates heat as it converts electric power.

The cooling system 10 includes a battery 2 that is an object to be cooled, a cooling liquid 12 that cools the battery 2, and a cooling circuit 14 through which the cooling liquid 12 flows.

Coolant 12 transports heat received from battery 2 . The cooling liquid 12 contains a liquid base material containing water and an orthosilicate, but does not contain an ionic antirust agent.

The base material is the material on which the coolant 12 is based. A liquid substrate means that it is in a liquid state when used. The base material contains a freezing point depressant in addition to water. Water is used because it has a large heat capacity, is inexpensive, and has low viscosity. A freezing point depressant is used to ensure a liquid state even if the ambient temperature is below freezing. A freezing point depressant dissolves in water and lowers the freezing point of water. Organic alcohols such as alkylene glycol or derivatives thereof are used as freezing point depressants. As alkylene glycol, for example, monoethylene glycol, monopropylene glycol, polyglycol, glycol ether and glycerin are used singly or as a mixture. The freezing point depressant is not limited to organic alcohols, and inorganic salts and the like may be used.

The orthosilicate is compatible with the base material. The orthosilicate is a compound that gives the coolant 12 an antirust function.

A compound represented by the general formula (I) is used as the orthosilicate.

In general formula (I), the substituents R ¹ to R ⁴ are the same or different, and are alkyl substituents having 1 to 20 carbon atoms, alkenyl substituents having 2 to 20 carbon atoms, and hydroxyalkyl substituents having 1 to 20 carbon atoms. Represents a substituent, a substituted or unsubstituted aryl substituent having 6 to 12 carbon atoms and/or a glycol ether-substituent of the formula —(CH ₂ —CH ₂ —O)n—R ⁵ . R ⁵ represents hydrogen or alkyl having 1 to 5 carbon atoms. n represents a number from 1 to 5;

Typical examples of orthosilicates are pure tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetra(n-propoxy)silane, tetra(isopropoxy)silane, tetra(n-butoxy)silane, tetra (t-butoxy)silane, tetra(2-ethylbutoxy)silane or tetra(2-ethylhexoxy)silane and also tetraphenoxysilane, tetra(2-methylphenoxy)silane, tetravinyloxysilane, tetraallyloxysilane, tetra(2-hydroxyethoxy)silane, tetra(2-ethoxyethoxy)silane, tetra(2-butoxyethoxy)silane, tetra(1-methoxy-2-propoxy)silane, tetra(2-methoxyethoxy)silane or tetra[ 2-[2-(2-methoxyethoxy)ethoxy]ethoxy]silane.

As the orthosilicate ester, in the general formula (I), the substituents R ¹ to R ⁴ are the same and an alkyl substituent having 1 to 4 carbon atoms or an alkyl substituent of the formula —(CH ₂ —CH ₂ —O)n Compounds are preferably used which represent a glycol ether substituent of -R ⁵ , where R ⁵ represents hydrogen, methyl or ethyl and n represents the number 1, 2 or 3.

The orthosilicate ester is contained in the cooling liquid 12 so that the concentration of silicon with respect to the entire cooling liquid 12 is 1 to 10000 mass ppm. The silicon concentration is preferably 1 ppm by mass or more and 2000 ppm by mass or less. Also, the silicon concentration is preferably higher than 2000 ppm by mass and equal to or lower than 10000 ppm by mass. The above orthosilicates are commercially available or can be prepared by simple transesterification of 1 equivalent of tetramethoxysilane with 4 equivalents of the corresponding long-chain alcohol or phenol and distillation of methanol.

Since the coolant 12 does not contain an ionic rust inhibitor, the conductivity of the coolant 12 is lower than when the coolant 12 contains an ionic rust inhibitor. The conductivity of the cooling liquid 12 is 50 μS/cm or less, preferably 1 μS/cm or more and 5 μS/cm or less. As a reference, the cooling liquid containing the liquid base material containing water and the ionic rust inhibitor includes engine cooling water used for cooling a vehicle engine. The electrical conductivity of the engine cooling water is 4000 μS/cm or higher. Thus, a coolant containing an ionic rust inhibitor for rust prevention has high conductivity and does not have electrical insulation.

The coolant 12 may contain an azole derivative as a rust preventive in addition to the orthosilicate.

Cooling circuit 14 includes cooler 16 , radiator 18 , pump 20 and hose 22 .

The cooler 16 cools the battery 2 by transferring heat from the battery 2 to the cooling liquid 12 through heat exchange between the battery 2 and the cooling liquid 12 . As shown in FIG. 2, the cooler 16 has a flow path forming member 17 and the like that form therein a flow path through which the cooling liquid 12 flows. The flow path forming member 17 is a heat transfer member. The cooler 16 cools the battery 2 by heat exchange between the cooling liquid 12 and the battery 2 via the passage forming member 17 . Thus, cooler 16 indirectly cools battery 2 with coolant 12 .

The radiator 18 is a heat exchanger that dissipates heat from the coolant 12 by exchanging heat with the air outside the vehicle. Air is supplied to the radiator 18 by the operation of an air blower (not shown). Pump 20 is a fluid machine that pumps coolant 12 . The hose 22 is a channel forming member that forms a channel through which the coolant 12 flows. Cooler 16 , radiator 18 and pump 20 are connected by hose 22 . This forms a cooling circuit 14 through which the coolant 12 circulates.

The cooling liquid 12 is circulated between the cooler 16 and the radiator 18 by operating the pump 20 . At this time, the coolant 12 receives heat from the battery 2 in the cooler 16 . At the radiator 18, the coolant 12 gives off heat to the air outside the vehicle. Thereby, the battery 2 is cooled.

As described above, the cooling system 10 of this embodiment includes the coolant 12 and the radiator 18 . The cooling liquid 12 contains a liquid base material containing water and an orthosilicate, but does not contain an ionic antirust agent.

Since the coolant 12 contains the orthosilicate, the coolant 12 has a function of preventing rust. Therefore, the coolant 12 does not have to contain an ionic rust inhibitor. Since the coolant 12 does not contain an ionic rust inhibitor, the coolant 12 has a lower electrical conductivity and a higher electrical insulation than a coolant containing an ionic rust inhibitor.

Furthermore, the base material of this cooling liquid 12 contains water, which has a higher heat transfer property than the above-described conventional cooling liquid. Therefore, the heat transferability of this cooling liquid 12 can be made higher than that of the above-described conventional cooling liquid.

Here, Table 1 shows the respective thermal conductivities of the cooling liquid 12 of the present embodiment, the conventional cooling liquid of silicone oil, and the fluorine-based inert liquid.

The coolant 12 of the first embodiment in Table 1 contains water and ethylene glycol as base materials. This coolant 12 contains tetraethoxysilane as an orthosilicate. The weight ratio of water to ethylene glycol is 1:1. The silicone oil in Table 1 is KF-96 series silicone oil from Shin-Etsu Silicone Co., Ltd. The fluorine-based inert liquids in Table 1 are 3M Novec 7000 series high-performance liquids. All of the thermal conductivities in Table 1 are values at 25°C.

As shown in Table 1, the thermal conductivity of the coolant 12 of this embodiment is 0.4 W/mK, which is higher than the thermal conductivity of the conventional coolants of 0.1 W/mK and 0.07 W/mK. is also expensive. This is because the thermal conductivity of the substrate containing water is higher than 0.1 W/mK.

There is a relationship between the thermal conductivity and the heat transfer coefficient that the higher the thermal conductivity, the higher the heat transfer coefficient. Therefore, the heat transfer coefficient of the coolant 12 of this embodiment is higher than that of the conventional coolant. That is, the heat transfer property of the cooling liquid 12 of this embodiment is higher than that of the conventional cooling liquid.

According to the cooling system 10 of the present embodiment, by using the cooling liquid 12 having higher heat transfer than the conventional cooling liquid, the size of each of the cooler 16 and the radiator 18 is reduced compared to the conventional cooling system. is possible. Therefore, the overall size of the cooling system 10 can be reduced.

(Second embodiment)
In this embodiment, the cooling circuit 14 includes a cooler 24 shown in FIG. 3 instead of the cooler 16 of the first embodiment. This cooler 24 directly cools the battery 2 with the coolant 12 . Specifically, the cooler 24 has a container 26 that stores the coolant 12 . The battery 2 is immersed in the coolant 12 inside the container 26 . The cooler 24 cools the battery 2 by directly transferring heat from the battery 2 to the cooling liquid 12 through heat exchange between the battery 2 and the cooling liquid 12 .

Other configurations of the cooling system 10 are the same as those of the first embodiment. Also in this embodiment, the same effect as in the first embodiment can be obtained.

(Third embodiment)
As shown in FIG. 4, the battery 2 has a conductive member 30 in this embodiment. An electrically insulating coating layer 32 is formed on the conductive member 30 to cover the surface of the conductive member 30 . That is, the battery 2 has the coating layer 32 . The coating layer 32 is composed of an organic compound, an inorganic compound, or a mixture thereof.

Examples of the conductive member 30 include electrodes, a case, and the like of the battery 2 . For example, when the conductive member 30 is the electrode of the battery 2, the coating layer 32 is formed on the surface of the electrode. Further, for example, when the conductive member 30 is a case forming the outer shape of the battery 2, a coating layer 32 is formed over the entire surface of the case. Thus, the coating layer 32 is formed on the surface of part or all of the battery 2 .

According to the present embodiment, even if the conductivity of the coolant 12 increases for some reason and the coolant 12 contacts the battery 2, it is possible to avoid the occurrence of a liquid junction in the battery 2. can.

(Other embodiments)
(1) In each of the above-described embodiments, the battery 2 is the object to be cooled. However, other in-vehicle equipment through which electricity flows, such as a motor generator, an inverter, and a computer mounted in the vehicle, may be the object to be cooled. The object to be cooled may be an object that is not mounted on the vehicle as long as it conducts electricity. Examples of such objects to be cooled include electric devices such as inverters provided in stationary charging stations for charging batteries of electric vehicles. Also, a stationary large-sized computer can be used.

(2) In each of the above-described embodiments, the coolant 12 does not contain an ionic rust inhibitor. However, as long as the coolant 12 has electrical insulation, the coolant 12 may contain an ionic rust inhibitor. Examples of ionic rust inhibitors include nitrites, molybdates, chromates, phosphonates, phosphates, sebacic acid, and triazole compounds. Here, "the coolant 12 has electrical insulation" means that the electrical conductivity of the coolant 12 is 500 μS/cm or less. This conductivity is measured at room temperature, eg, 25°C. According to the experimental results of the present inventors, when the electrical conductivity of the coolant is 500 μS/cm or less, it is possible to suppress the occurrence of a liquid junction in the object to be cooled. In order to suppress the liquid junction, the electrical conductivity of the coolant 12 is preferably 100 μS/cm or less, more preferably 10 μS/cm or less.

In this case as well, the cooling liquid has an anticorrosion function because the cooling liquid contains the orthosilicate. For this reason, the amount of the ionic rust preventive agent contained in the coolant can be reduced compared to a coolant (for example, engine coolant) containing an ionic rust preventive agent for rust prevention. That is, the electrical conductivity of the cooling liquid can be lowered compared to the cooling liquid containing an ionic rust inhibitor for rust prevention. This allows the cooling liquid to have electrical insulation.

(3) The present invention is not limited to the above-described embodiments, but can be modified as appropriate within the scope of the claims, and includes various modifications and modifications within the equivalent range. Moreover, the above-described embodiments are not unrelated to each other, and can be appropriately combined except when combination is clearly impossible. Further, in each of the above-described embodiments, it goes without saying that the elements that constitute the embodiment are not necessarily essential unless explicitly stated as essential or clearly considered essential in principle. stomach. In addition, in each of the above-described embodiments, when numerical values such as the number, numerical value, amount, range, etc. of the constituent elements of the embodiment are mentioned, when it is clearly stated that they are particularly essential, and when they are clearly limited to a specific number in principle is not limited to that particular number. In addition, in each of the above-described embodiments, when referring to the material, shape, positional relationship, etc. of the constituent elements, unless otherwise specified or in principle limited to a specific material, shape, positional relationship, etc. , its material, shape, positional relationship, and the like.

(summary)
According to the first aspect shown in part or all of the above embodiments, a cooling system for cooling an object to be cooled through which electricity flows includes a cooling liquid for cooling the object to be cooled and the heat of the cooling liquid is released. The cooling liquid includes a liquid base containing water and an orthosilicate that is compatible with the base, and has electrical insulation.

According to a second aspect, a cooling system for cooling an object to be cooled through which electricity flows includes a cooling liquid for cooling the object to be cooled, and a radiator for releasing heat of the cooling liquid. The coolant contains a liquid base material containing water and an orthosilicate that is compatible with the base material, and does not contain an ionic rust inhibitor.

Moreover, according to the third aspect, the electrical conductivity of the coolant is 500 μS/cm or less. Thus, the coolant has electrical insulation with a conductivity of 500 μS/cm or less. As a result, it is possible to suppress the occurrence of a liquid junction in the object to be cooled.

Moreover, according to a fourth aspect, the cooling system further includes a cooler. The cooler has a channel forming member that forms a channel through which the coolant flows. The cooler cools the object to be cooled by heat exchange between the cooling fluid and the object to be cooled via the flow path forming member.

The configuration of the fourth aspect can be adopted in the first to third aspects. According to this, it is possible to reduce the size of the cooler compared to the conventional cooling system by using the cooling liquid having higher heat transfer property than the conventional cooling liquid. Therefore, it is possible to downsize the cooling system.

Moreover, according to the fifth aspect, the cooling system further includes an object to be cooled. The object to be cooled has a conductive member and an electrically insulating coating layer covering the surface of the conductive member. According to this, even if the conductivity of the cooling liquid is increased for some reason, it is possible to avoid the occurrence of liquid junction in the object to be cooled.

12 Coolant 14 Cooling Circuit 16 Cooler 17 Flow Path Forming Member 18 Radiator

Claims (5)

A cooling system for cooling an object to be cooled (2) through which electricity flows,
a cooling liquid (12) for cooling the object to be cooled;
A radiator (18) for releasing heat of the cooling liquid,
The cooling system according to claim 1, wherein the coolant contains a liquid base material containing water and an orthosilicate that is compatible with the base material, and has electrical insulation. A cooling system for cooling an object to be cooled (2) through which electricity flows,
a cooling liquid (12) for cooling the object to be cooled;
A radiator (18) for releasing heat of the cooling liquid,
The cooling system, wherein the cooling liquid contains a liquid base material containing water, an orthosilicate that is compatible with the base material, and does not contain an ionic rust inhibitor. 3. The cooling system of claim 1 or 2, wherein the coolant has a conductivity of 500 [mu]S/cm or less. Cooling that has a flow path forming member (17) that forms a flow path through which the cooling liquid flows, and that cools the object to be cooled by heat exchange between the cooling liquid and the object to be cooled via the flow path forming member A cooling system according to any one of the preceding claims, further comprising a vessel (16). further comprising the object to be cooled;
A cooling system according to any one of claims 1 to 4, wherein the object to be cooled comprises a conductive member (30) and an electrically insulating coating layer (32) covering the surface of the conductive member.

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