WO2019158993A1

WO2019158993A1 - Reserve tank

Info

Publication number: WO2019158993A1
Application number: PCT/IB2019/000054
Authority: WO
Inventors: Tomoya Hayakawa; Takaharu Nagatoshi; Masataka MINAMIGAWA; Junichi Suematsu; Masashi Shibata
Original assignee: Toyota Jidosha Kabushiki Kaisha; Denso Corporation
Priority date: 2018-02-19
Filing date: 2019-02-18
Publication date: 2019-08-22
Also published as: JP2019143505A; WO2019158993A8

Abstract

A reserve tank includes tank portions that stores liquid coolant for cooling systems with different temperature ranges, respectively, the tank portions being disposed adjacent to each other and an integrated body, and a heat insulating layer that is disposed between the tank portions that are adjacent to each other out of the tank portions, the heat insulating later having thermal conductivity lower than thermal conductivity of a member that configures the tank portions adjacent to each other.

Description

RESERVE TANK

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a reserve tank mounted on a vehicle, especially to a reserve tank in which tank portions are adjacent to and integrated with each other, the tank portions storing liquid coolant for different cooling systems, respectively.

2. Description of Related Art

[0002] It is known that a reserve tank is provided in a cooling system (circuit) in a vehicle on which a water cooled engine or the like is mounted. The reserve tank is provided in order to maintain a constant amount of liquid coolant that circulates in the cooling system by absorbing volume expansion of the liquid coolant due to a temperature increase, and also to remove residual air unavoidably contained in the liquid coolant (gas-liquid separation). Further, the reserve tank is provided in order to facilitate inspection and management of the amount of the liquid coolant circulating in the cooling system.

[0003] In addition to this, recently, due to an increase in an engine that is downsized and turbocharged by using a supercharger, a vehicle in which an air-to-water intercooler is mounted is on the rise. The air-to-water intercooler is used to reduce temperature of supercharged high-temperature suction air so that charging efficiency of air to be introduced into a cylinder is improved during a high-load operation (for example, see Japanese Unexamined Patent Application Publication No. 2017-72092 (JP 2017-72092 A)).

SUMMARY OF THE INVENTION [0004] In JP 2017-72092 A stated above, it is only described that engine coolant is cooled by a radiator, and intercooler coolant is cooled by a sub-radiator. However, because engine coolant and intercooler coolant have different temperature ranges from each other, it is preferred that reserve tanks (a reserve tank for cooling the engine, and a reserve tank for cooling the intercooler) are provided in an engine cooling system and an intercooler cooling system, respectively.

[0005] When two reserve tanks are provided, problems like a cost increase happen. Also, considering that a reserve tank is normally disposed inside an engine compartment, when two reserve tanks are disposed inside an engine compartment, there is a problem that space for disposing other onboard equipment is restricted.

[0006] Therefore, it is considered to use a reserve tank in which a tank portion for cooling an engine and a tank portion for cooling an intercooler are adjacent to and integrated with each other in order to achieve effective utilization of space inside an engine compartment and cost reduction.

[0007] However, in the reserve tank in which the tank portion for cooling an engine and the tank portion for cooling an intercooler are adjacent to and integrated with each other, temperature of intercooler coolant with a relatively low temperature range increases due to an influence of engine coolant with a relatively high temperature range. Therefore, there is a problem that cooling performance in the intercooler cooling system is degraded, and an engine output is reduced as well.

[0008] These problems generally happen not only in a vehicle having a water cooled engine and an air-to-water intercooler, but also in any case where a reserve tank having tank portions that are adjacent to and integrated with each other, and store liquid coolant for two or more different cooling systems with different temperature ranges, respectively, such as a water cooled engine and a water cooled inverter in a hybrid vehicle.

[0009] The invention provides a reserve tank in which tank portions for cooling systems with different temperature ranges are adjacent to and integrated with each other, and mutual temperature influence between the tank portion are reduced.

[0010] In a reserve tank according to an aspect of the invention, by providing a heat insulating layer with relatively lower thermal conductivity between the tank portions adjacent to each other, a mutual temperature influence between the tank portions is reduced.

[0011] Specifically, a reserve tank according to the aspect of the invention includes tank portions that stores liquid coolant for cooling systems with different temperature ranges, respectively. The tank portions are disposed adjacent to each other and an integrated body.

[0012] The reserve tank includes a heat insulating layer that is disposed between the tank portions that are adjacent to each other out of the tank portions. The heat insulating layer has thermal conductivity lower than that of a member that configures the tank portions adjacent to each other.

[0013] In the aspect, the phrase "between the tank portions that are adjacent to each other out of the tank portions" means, for example, "between a tank portion A and a tank portion B", and "between the tank portion B and a tank portion C" when the tank portion A, the tank portion B, and the tank portions C are adjacent to each other in this order and integrated with each other.

[0014] With the configuration, because the tank portions are adjacent to and integrated with each other, effective utilization of space inside an engine compartment and cost reduction are achieved.

[0015] In addition, as the heat insulating layer with lower thermal conductivity than that of the member configuring the tank portions is interposed between the tank portions adjacent to each other, it is possible to restrain an influence of liquid coolant with a relatively high temperature range on liquid coolant with a relatively low temperature range. Thus, it is possible to ensure that degradation of cooling performance in a cooling system with a relatively low temperature range is restrained.

[0016] Also, in the above aspect, the heat insulating layer may be an air space provided between the tank portions adjacent to each other.

[0017] Generally, thermal conductivity decreases in the order of solids, liquids, and gases. Therefore, with the aspect, it is possible to ensure that a mutual temperature influence between the tank portions is reduced with a simple configuration where the air space is provided between the tank portions adjacent to each other.

[0018] Further, in the foregoing configuration, the air space may communicate with the outside of the reserve tank. Furthermore, the reserve tank may include an air hole that allows the outside of the reserve tank and the air space to communicate with each other.

[0019] If the air space is formed as a closed space provided between the tank portions adjacent to each other, air inside the closed space expands and contracts repeatedly, thereby allowing pressure to act on the reserve tank repeatedly. However, with the above configuration, by allowing the space provided between the tank portions adjacent to each other and the outside to communicate with each other, pressure is allowed to escape outside even when air expands. Therefore, it is possible to restrain an influence of expansion and contraction of air.

[0020] Moreover, in the above aspect, the heat insulating layer may be a heat insulator sandwiched between the tank portions adjacent to each other.

[0021] With the configuration, for example, by using a heat insulator with lower thermal conductivity than that of air, it is possible to more reliably restrain an influence of liquid coolant with a relatively high temperature range on liquid coolant with a relatively low temperature range.

[0022] As described above, with the reserve tank according to the invention, it is possible to reduce a mutual temperature influence between tank portions that are adjacent to and integrated with each other, the tank portions being formed for cooling systems with different temperature ranges, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: FIG. 1 is a schematic back view of a reserve tank according to an embodiment of the invention;

FIG. 2 is a schematic view of the reserve tank mounted on an engine radiator;

FIG. 3 is a schematic plan view of the reserve tank;

FIG. 4 is a schematic side view of the reserve tank;

FIG. 5 is a sectional view taken along the arrows V - V in FIG. 3;

FIG. 6 is a simplified view of the reserve tank;

FIG. 7 is a simplified view of a reserve tank according to modification 1 ; and

FIG. 8 is a simplified view of a reserve tank according to modification 2.

DETAILED DESCRIPTION OF EMBODIMENTS

[0024] Hereinafter, modes for carrying out the invention are described based on the drawings. In the drawings, an arrow Up represents an upward direction, and an arrow Fr represents a front side (a front side in a vehicle front-rear direction), an arrow Rh represents a right side (a right side in a vehicle width direction), and an arrow Lf represents a left side (a left side in the vehicle width direction).

Reserve Tank

[0025] FIG. 1 is a schematic back view of a reserve tank 1 according to an embodiment. FIG. 2 is a schematic view of the reserve tank 1 mounted on an engine radiator 41. The reserve tank 1 is mounted on a vehicle that includes an engine (not shown) downsized and turbocharged by using a supercharger (not shown). As shown in FIG. 2, the reserve tank 1 is mounted on the engine radiator 41 and is disposed at inside an engine compartment (not shown). In the following description, front-rear, upper-lower, and right-left directions are defined based on a position of the reserve tank 1 mounted on a vehicle, unless otherwise specified. For example, an upper surface 21 is a surface facing upward in a state where the reserve tank 1 is mounted on a vehicle. Also, a front side surface 23 is a surface facing frontward in the state where the reserve tank 1 is mounted on a vehicle.

[0026] The reserve tank 1 is made from transparent or semitransparent resin such as acrylic resin or polycarbonate resin. As shown in FIG. 1 , the reserve tank 1 includes a tank body portion 2 that stores engine coolant (liquid coolant), first and second tank caps 5, 6, and first to third mounting portions 7, 8, 9 (see FIG. 4). The first and second tank caps 5, 6 are detachably mounted on first and second coolant injection portions 14, 15, respectively, that are formed in the tank body portion 2 so that the tank caps 5, 6 pressurize and seal the first and second coolant injection portions 14, 15, respectively. The first to third mounting portions 7, 8, 9 are provided in order to mount the tank body portion 2 on the engine radiator 41 as shown in FIG. 2.

[0027] FIG. 3 is a schematic plan view of the reserve tank 1, FIG. 4 is a side view of the reserve tank 1, and FIG. 5 is a sectional view taken along the arrows V - V in FIG. 3. The tank body portion 2 has a two-piece structure, and is formed into a three-dimensional shape with space inside by connecting a front member 3 and a rear member 4 in the front-rear direction as shown in FIG. 3 and FIG. 4.

[0028] As shown in FIG. 1, FIG. 3, and FIG. 4, the tank body portion 2 is formed into a polyhedral shape that includes the upper surface 21, a lower surface 22, the front side surface 23 extending downwardly from a front end portion of the upper surface 21, a rear side surface 24 extending downwardly from a rear end portion of the upper surface 21 , a first right side surface 25 extending downwardly from a right end portion of the upper surface 21, a second right side surface 26 retracting to the left side from a lower end portion of the first right side surface 25 and extending downwardly, a first left side surface 27 extending downwardly from a left end portion of the upper surface 21, and a second left side surface 28 that is curved downwardly to the right side from a lower end portion of the first left side surface 27.

[0029] In a vehicle according to the embodiment where the downsized and turbocharged engine is provided, an air-to-water intercooler (not shown) is mounted in order to reduce temperature of supercharged high-temperature suction air so that charging efficiency of air to be introduced into a cylinder is improved during a high-load operation. Since temperature of the engine coolant (for example, 105 °C maximum) and temperature of intercooler coolant (for example, 90 °C maximum) are different, reserve tanks for the two cooling systems for cooling the engine and the intercooler, respectively, are required. However, the reserve tank 1 employed in the embodiment has the tank portions 11, 12 for the two cooling systems for cooling the engine and the intercooler, respectively, and the tank portions 11, 12 are adjacent to and integrated with each other in order to achieve effective utilization of space inside the engine compartment and cost reduction.

[0030] Specifically, as shown in FIG. 5, the tank body portion 2 includes the first tank portion 11, the second tank portion 12, and an inner wall portion 13. The first tank portion 11 stores engine coolant, and the second tank portion 12 stores intercooler coolant and is adjacent to a right side of the first tank portion 11 in the vehicle width direction and integrated with the first tank portion 11. The inner wall portion 13 divides the first tank portion 11 and the second tank portion 12 from each other. As shown in FIG. 5, a number of ribs 16, 17 are provided inside the first tank portion 11 and the second tank portion 12, respectively, and thus pluralities of internal spaces 11 a, 12a are formed inside the first tank portion 11 and the second tank portion 12, respectively. At the same time, the reserve tank 1 is given rigidity. The internal spaces lla formed inside the first tank portion 11 communicate with each other through communication holes (not shown), and the engine coolant passes through the internal spaces lla sequentially. Similarly, the internal spaces l2a formed inside the second tank portion 12 communicate with each other through communication holes (not shown), and the intercooler coolant passes through the internal spaces 12a sequentially.

[0031] The first tank portion 11 is surrounded by a left portion of the upper surface 21 (a portion located on the left side with respect to the inner wall portion 13), a left portion of the lower surface 22, a left portion of the front side surface 23, a left portion of the rear side surface 24, the first left side surface 27, and the second left side surface 28 (to be more precise, wall portions that configure the above-mentioned surfaces, respectively). In the left portion of the upper surface 21 (to be more precise, the wall portion that configures the upper surface 21), the first coolant injection portion 14 is formed for injecting the engine coolant into the first tank portion 11. As described earlier, the first coolant injection portion 14 is pressurized and sealed by the first tank cap 5 that is mounted detachably. Thus, pressure inside the first tank portion 11 is increased, and the engine coolant is restrained from boiling.

[0032] The engine coolant is first supplied to the engine, and then divided into flows to the engine radiator 41 and the reserve tank 1. The engine coolant that is divided and flows into the reserve tank 1 enters the first tank portion 11 from a first inflow portion 1 lb formed in the left portion of the rear side surface 24, passes through the internal spaces lla divided by the ribs 16, and flows out from an first outflow portion l lc formed in the left portion of the lower surface 22. Then, after the engine coolant joins the engine coolant that flows out from the engine radiator 41, the engine coolant is supplied to the engine again. Thus, volume expansion of the engine coolant caused by a temperature rise is absorbed, and an amount of coolant circulating in an engine cooling system (circuit) is maintained constant. At the same time, because flow speed of the engine coolant is reduced as the engine coolant passes through the internal spaces lla, it is possible to remove residual air that is unavoidably contained in the engine coolant (gas-liquid separation).

[0033] The reserve tank 1 has a function of facilitating inspection and management of an amount of liquid coolant, in addition to the function of maintaining a constant amount of liquid coolant and the gas-liquid separation function described above. More specifically, in the rear side surface 24 that is the side surface surrounding the first and second tank portions 11, 12 of the reserve tank 1, a portion corresponding to the first tank portion 11 is provided with a scale for checking a liquid quantity (hereinafter, also referred to as an F - L line) 31 for the engine coolant together with letters "Full" and "Low". "Full" represents the upper limit of the amount of the liquid coolant, and "Low" represents the lower limit of the amount of the liquid coolant. As an operator compares a level of the engine coolant that can be seen through the semitransparent reserve tank 1 to the F - L line 31 , the operator is able to inspect and manage an amount of the engine coolant easily.

[0034] As shown in FIG. 3, a retracted surface 30 is formed in a portion of the front side surface 23, the portion corresponding to the first tank portion 11. The retracted surface 30 is formed by retracting the portion to an inner side (the rear side) of the tank body portion 2 so that the retracted surface 30 is continuous with the upper surface 21, and an F - L line for the engine coolant is provided on the retracted surface 30. By forming the retracted surface 30 so as to be continuous with the upper surface 21, the retracted surface 30 (the F - L line) can be visually recognized from above or diagonally above the reserve tank 1 even if obstacles are present adjacent to the front side surface 23 of the reserve tank 1.

[0035] Meanwhile, the second tank portion 12 is surrounded by a right portion of the upper surface 21 (a right portion with respect to the inner wall portion 13), a right portion of the lower surface 22, a right portion of the front side surface 23, a right portion of the rear side surface 24, the first right side surface 25, and the second right side surface 26 (to be more precise, wall portions that configure the above-mentioned surfaces, respectively). The second coolant injection portion 15 is formed in the right portion of the upper surface 21 for injecting the intercooler coolant into the second tank portion 12. As described earlier, the second coolant injection portion 15 is pressurized and sealed by the second tank cap 6 that is mounted detachably.

[0036] In the upper surface 21, a recessed stripe 21 a is formed at a position corresponding to the inner wall portion 13 and extends in the vehicle front-rear direction. Also, across the recessed stripe 2 la, the right portion of the upper surface 21 corresponding to the second tank portion 12 is one step lower than the left portion of the upper surface 21 corresponding to the first tank portion 11. This reminds an operator who injects the engine coolant and the intercooler coolant that the reserve tank 1 is made of the integrated tank portions 11, 12 for the two cooling systems. Thus, the operator does not forget to inject coolant into both tank portions. This means that the first tank portion 11 and the second tank portion 12 are an integrated object.

[0037] The intercooler coolant is first supplied to the intercooler, flows into the second tank portion 12 from a second inflow portion l2b formed in the right portion of the lower surface 22, and passes through the internal spaces l2a divided by the ribs 17. Then, the intercooler coolant is supplied to an intercooler radiator (not shown) from a second outflow portion l2c formed in the right portion of the front side surface 23. Thus, volume expansion of the intercooler coolant caused by a temperature rise is absorbed, and an amount of the coolant circulating in the intercooler cooling system (circuit) is maintained constant. At the same time, it is possible to remove residual air that is unavoidably contained in the intercooler coolant (gas-liquid separation) while the intercooler coolant is passing through the internal spaces l2a.

[0038] An F - L line 32 is formed on the first right side surface 25 that is the side surface surrounding the second tank portion 12 of the reserve tank 1. As an operator compares a liquid level of the intercooler coolant that can be seen through the semitransparent reserve tank 1 to the F - L line 32, the amount of the intercooler coolant is inspected and managed easily.

[0039] The reserve tank 1 configured as described above is mounted on the engine radiator 41 while being supported at three points as the first mounting portion 7, the second mounting portion 8, and the third mounting portion 9 are fastened to a radiator shroud (not shown) by bolts on the rear side of the engine radiator 41. The first mounting portion 7 is provided in an upper end portion of a left end of the front side surface 23, the second mounting portion 8 is provided in a right end portion of the front side surface 23, and the third mounting portion 9 is provided in a lower end portion of a right end of the front side surface 23. As shown in FIG. 2, the reserve tank 1 is mounted oh an upper end portion of a right end of the engine radiator 41 on the rear side, and is disposed so that the curved second left side surface 28 goes along a fan shroud 43 that covers a fan 42 driven by the engine.

Inner Wall Portion

[0040] As described above, in the embodiment, the reserve tank 1 is employed in which the first tank portion 11 for cooling the engine and the second tank portion 12 for cooling the intercooler are adjacent to and integrated with each other in order to achieve effective utilization of space inside the engine compartment and cost reduction. However, with such a reserve tank 1, temperature of the intercooler coolant with a relatively low temperature range increases due to an influence of the engine coolant with a relatively high temperature range. Therefore, it is assumed that cooling performance of the intercooler cooling system may be degraded, and an engine output may be reduced as well.

[0041] Thus, in the reserve tank 1 according to the embodiment, a heat insulating layer having lower thermal conductivity than that of members that configure the tank portions 11, 12 is interposed between the first tank portion 11 and the second tank portion 12 that are adjacent to each other in order to reduce a mutual temperature influence between the tank portions 11, 12. Specifically, in the reserve tank 1 according to the embodiment, an air space AL is interposed between the first tank portion 11 and the second tank portion 12 adjacent to each other.

[0042] To be more specific, as shown in FIG. 5, the inner wall portion 13 includes a first inner wall portion 13A and a second inner wall portion 13B. The first inner wall portion 13 A defines the right side of the first tank portion 11, and the second inner wall portion 13B is provided at an interval from the first inner wall portion 13 A in the vehicle width direction, and defines the left side of the second tank portion 12. In FIG. 5, the first inner wall portion 13A and the second inner wall portion 13B are painted in black to be emphasized. Thus, as shown in a simplified view of FIG. 6, between the first tank portion 11 and the second tank portion 12, a space S is formed that is surrounded by the wall portion that configures the front side surface 23, the wall portion that configures the rear side surface 24, the wall portion that configures the upper surface 21, the wall portion that configures the lower surface 22, the first inner wall portion 13 A, and the second inner wall portion 13B, in front, rear, upper, lower, right, and left directions. The space S forms the air space AL.

[0043] Generally, thermal conductivity decreases in the order of solids, liquids, and gases. Therefore, because the air space AL is provided between the first tank portion 11 and the second tank portion 12, it is possible to ensure that a mutual temperature influence between the tank portions 11, 12 is reduced compared to a case where the first tank portion 11 and the second tank portion 12 are adjacent to each other directly.

[0044] In the reserve tank 1 according to the embodiment, the first tank portion 11 for cooling an engine, and the second tank portion 12 for cooling an intercooler are adjacent to and integrated with each other. Therefore, a temperature increase of intercooler coolant with a relatively low temperature range due to an influence of engine coolant with a relatively high temperature range is restrained reliably while achieving effective utilization of space inside the engine compartment and cost reduction. Accordingly, it is ensured that a reduction of an engine output due to degradation of cooling performance of the intercooler cooling system is restrained.

[0045] As shown in FIG. 5, in the reserve tank 1 according to the embodiment, the first inner wall portion 13A is connected with the ribs 16 formed inside the first tank portion 11, and the second inner wall portion 13B is connected with the ribs 17 formed inside the second tank portion 12. Therefore, rigidity of the reserve tank 1 is ensured even though the air space AL is provided inside the reserve tank 1.

Modifications

[0046] Next, modifications of the embodiment are described. Constituents similar to those of the embodiment are denoted by the same reference numerals, and detailed description is omitted for convenience.

Modification 1

[0047] This modification is different from the embodiment described above in that a space S communicates with outside. This means an air space AL communicates with outside. Description below mainly pertains to differences from the embodiment.

[0048] FIG. 7 is a schematic view of a reserve tank 1A according to the modification 1. As shown in FIG. 7, in the reserve tank 1A, an air hole 2 lb is formed so as to pass through a wall portion that configures an upper surface 21 (a bottom portion of a recessed stripe 2 la) and allows the outside of the reserve tank 1A and a space S (an air space AL) to communicate with each other. Also, an air hole 22a is formed so as to pass through a wall portion that configures a lower surface 22 and allows the outside of the reserve tank 1 A and the space S (the air space AL) to communicate with each other.

[0049] Because the space S provided between the first tank portion 11 and the second tank portion 12 and the outside are allowed to communicate with each other as described above, even when air inside the space S expands, pressure is allowed to escape outside. Therefore, an influence caused by expansion and contraction of air inside the space S is restrained. Thus, repeated action of pressure on the reserve tank 1A due to repeated expansion and contraction of air inside the space S is restrained.

Modification 2

[0050] This modification is different from the foregoing embodiment in that a heat insulator 50 is interposed between a first tank portion 11 and a second tank portion 12. Description below mainly pertains to differences from the embodiment

[0051] FIG. 8 is a schematic view of a reserve tank 1B according to the modification 2. As shown in FIG. 8, in the reserve tank 1B, a space S between a first inner wall portion 13A and a second inner wall portion 13B is filled with the heat insulator 50. The heat insulator 50 is, for example, a fiber-based heat insulator or plastic-based heat insulator in which a number of air bubbles are contained. Gas with higher heat insulation performance than air is confined in the air bubbles.

[0052] Because the heat insulator 50 with higher heat insulation performance than air is interposed between the first tank portion 11 and the second tank portion 12, temperature increase of intercooler coolant due to an influence of engine coolant is restrained even more reliably.

Other Embodiments

[0053] The invention is not limited to the embodiment, and may be carried out in various other forms without departing from the spirit and main characteristics of the invention.

[0054] In the embodiment, the invention is applied to the reserve tank 1 in which the two tank portions 11, 12 storing liquid coolant for the two cooling systems, respectively, are adjacent to and integrated with each other. However, the invention is not limited to this. The invention may also be applied to a reserve tank in which three or more tank portions storing liquid coolant for three or more cooling systems, respectively, are adjacent to and integrated with each other.

[0055] Moreover, in the embodiment, the tank portions are integrated with each other so that the tank portions are adjacent to each other in the right-left direction. However, the invention is not limited to this as long as a heat insulating layer is interposed between tank portions that are adjacent to each other. For example, tank portions may be integrated with each other so that the tank portions are adjacent to each other in the upper-lower direction or the front-rear direction.

[0056] Further, in the embodiment, the invention is applied to the transparent or semitransparent resin reserve tank 1 , but a material of the reserve tank 1 is not particularly limited, and the invention may be applied to a metal reserve tank.

[0057] In the embodiment, the invention is applied to a vehicle on which the downsized and turbocharged engine and the air-to-water intercooler are mounted. However, the invention is not limited to this as long as a vehicle includes a water-cooled equipment. For example, the invention is applicable to a hybrid vehicle in which an engine, an inverter and so on are cooled, and an electric vehicle in which two or more pieces of equipment are water-cooled.

[0058] As described above, the foregoing embodiment is just an example in every aspect, and should not be narrowly interpreted. Further, all modifications and changes pertaining to an equivalent scope to the claims fall within the scope of the invention.

[0059] According to the invention, it is possible to reduce a mutual temperature influence between tank portions that are adjacent to each other. Therefore, the invention is extremely useful when it is applied to a reserve tank in which tank portions for more than one cooling systems having different temperature ranges are adjacent to and integrated with each other.

Claims

CLAIMS:

1. A reserve tank comprising:

tank portions that stores liquid coolant for cooling systems with different temperature ranges, respectively, the tank portions being disposed adjacent to each other, and the tank portions being an integrated body; and

a heat insulating layer that is disposed between the tank portions that are adjacent to each other out of the tank portions, the heat insulating later having thermal conductivity lower than thermal conductivity of a member that configures the tank portions adjacent to each other.

2. The reserve tank according to claim 1, wherein the heat insulating layer is an air space provided between the tank portions adjacent to each other.

3. The reserve tank according to claim 2, wherein the air space communicates with an outside of the reserve tank.

4. The reserve tank according to claim 3, wherein the reserve tank has an air hole that allows the outside of the reserve tank and the air space to communicate with each other.

5. The reserve tank according to claim 1, wherein the heat insulating layer is a heat insulator sandwiched between the tank portions adjacent to each other.