Air conditioning system

Abstract

To provide an air conditioning system that can improve initial heating performance while suppressing electric power consumption.SOLUTION: An air conditioning system comprises a heat pump cycle 10 that has refrigerant piping 20 through which a refrigerant can circulate and a compressor 30 that can compress the refrigerant. A heating part 100 that can heat a refrigerant is provided on the refrigerant piping 20 which is arranged at an upstream side or at a downstream side or both upstream / downstream sides of the compressor 30. The heating part 100 has an outer peripheral wall 101 and a bulkhead 105, arranged inside the outer peripheral wall 101, which comparts and forms a plurality o cells 104 extending from a first end face 102 to a second end face 103. At least the bulkhead 105 is constituted of materials having PTC characteristics.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to an air conditioning system. [Background technology]

[0002] Air conditioning systems capable of cooling and heating using a heat pump cycle are known. Because of their advantages, such as power saving, these systems are also used in vehicles such as battery electric vehicles (BEVs). A heat pump cycle system has a configuration in which components such as a compressor, a condenser, an evaporator, and an expansion valve are connected in a ring shape by refrigerant piping, and can perform cooling and heating by utilizing the heat of vaporization and condensation of the refrigerant.

[0003] However, because air conditioning systems using a heat pump cycle convert outside air into heat, they have a problem of reduced initial heating performance (slow heating start-up) in cold weather. Specifically, in cold weather, the temperature of the refrigerant flowing through the heat pump cycle is low, making it difficult for the refrigerant temperature and pressure to rise when heating starts. As a result, heating start-up is slow and it takes a long time to supply warm air. To solve this problem, Patent Document 1 proposes an air conditioning system (vehicle air conditioner) that controls the amount of air sent to the vehicle interior heat exchanger, which acts as a radiator, to decrease when heating starts. Patent Document 2 also proposes an air conditioning system (vehicle air conditioner) that increases the amount of refrigerant heated by the refrigerant heater to speed up the start of heating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-24371 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-131914 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the air conditioning system of Patent Document 1 reduces the amount of air sent to the radiator (interior heat exchanger) when heating starts, thereby reducing the amount of heat exchanged between the refrigerant discharged from the compressor and the outside air as it flows through the radiator, making it easier to raise the temperature of the refrigerant.However, since the refrigerant is not heated, the initial heating performance cannot be said to be sufficient. Furthermore, the air conditioning system of Patent Document 2 consumes a lot of power because it heats the refrigerant with a refrigerant heater that is made up of a sheath heater (electric heater). For this reason, if this air conditioning system is used in an electric vehicle, for example, there is a problem that the driving range is significantly reduced due to energy loss.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide an air conditioning system that can improve initial heating performance while reducing power consumption. [Means for solving the problem]

[0007] As a result of extensive research into air conditioning systems using a heat pump cycle, the inventors have discovered that the above-mentioned problems can be solved by providing a predetermined heating section in a refrigerant pipe through which the refrigerant flows and heating the refrigerant, and have thus completed the present invention. That is, the present invention is exemplified as follows.

[0008] [1] An air conditioning system equipped with a heat pump cycle having a refrigerant pipe through which a refrigerant can circulate and a compressor capable of compressing the refrigerant, a heating unit capable of heating the refrigerant is provided in the refrigerant pipe on the upstream side, downstream side, or both of the upstream side and downstream side of the compressor with respect to the flow direction of the refrigerant; The heating section is an air conditioning system having a honeycomb structure having an outer peripheral wall and partition walls arranged inside the outer peripheral wall and defining a plurality of cells extending from a first end face to a second end face, and at least the partition walls are made of a material having PTC properties.

[0009] [2] Further comprising a control unit that controls the heat pump cycle and the heating unit, The air conditioning system according to [1], wherein the control unit controls the honeycomb structure to apply a voltage to heat the refrigerant when the heating operation mode of the heat pump cycle starts.

[0010] [3] The heat pump cycle further includes a condenser that performs heat exchange between the air circulating in the air conditioning duct and the refrigerant, The air conditioning system according to [2], wherein the heating operation mode includes compressing the refrigerant with the compressor and introducing the refrigerant discharged from the compressor into the condenser to heat the air.

[0011] [4] The heat pump cycle an evaporator that performs heat exchange between the air circulating in the air conditioning duct and the refrigerant; an outdoor heat exchanger that exchanges heat between outside air and the refrigerant; The air conditioning system according to any one of [1] to [3], further comprising:

[0012] [5] The air conditioning system described in [4], wherein the heating unit is provided in the refrigerant piping between the compressor and the condenser, between the compressor and the evaporator or the outdoor heat exchanger, or in both of these.

[0013] [6] The air conditioning system according to any one of [1] to [5], wherein the material having PTC properties is mainly composed of barium titanate.

[0014] [7] The air conditioning system according to any one of [1] to [6], wherein the air conditioning system is for a vehicle. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an air conditioning system that can improve initial heating performance while suppressing power consumption. [Brief explanation of the drawings]

[0016] [Figure 1A] 1 is a schematic configuration diagram of a vehicle air conditioning system according to an embodiment of the present invention, illustrating an operating state in a heating operation mode. [Figure 1B] 1 is a schematic diagram of a vehicle air conditioning system according to an embodiment of the present invention, illustrating an operating state in a cooling operation mode. [Figure 1C] 1 is a schematic diagram of a vehicle air conditioning system according to an embodiment of the present invention, showing an operating state in another cooling operation mode. FIG. [Figure 2A] 3 is a schematic diagram of a cross section parallel to the direction in which the cells of the heating unit used in the air conditioning system according to the embodiment of the present invention extend. FIG. [Figure 2B] 2B is a schematic cross-sectional view of the heating unit taken along line aa' in FIG. 2A. FIG. [Figure 3A] FIG. 10 is a schematic diagram of a cross section parallel to the extending direction of cells of another heating unit used in the air conditioning system according to the embodiment of the present invention; [Figure 3B] 3B is a schematic cross-sectional view of the heating unit taken along line bb' in FIG. 3A. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The air conditioning system of the present invention includes a heat pump cycle having a refrigerant piping through which a refrigerant can circulate and a compressor capable of compressing the refrigerant. A heating unit capable of heating the refrigerant is provided in the refrigerant piping upstream, downstream, or both of the compressor, based on the refrigerant flow direction. The heating unit includes a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells extending from a first end face to a second end face, at least the partition walls being made of a material having PTC (Positive Temperature Coefficient) properties. This configuration of the air conditioning system of the present invention enables rapid heating of the refrigerant in cold weather, thereby improving initial heating performance. Furthermore, the air conditioning system of the present invention consumes less power than air conditioning systems that heat the refrigerant using conventional sheath heaters (electric heaters), thereby contributing to energy savings and extending the driving range, particularly when applied to electric vehicles.

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention are also within the scope of the present invention.

[0019] The air conditioning system of the present invention can be used in various facilities and products that require air conditioning. For example, the air conditioning system of the present invention can be used in air conditioners used in offices and homes, home appliances such as refrigerators and washer-dryers, and various vehicles such as automobiles. Among these, the air conditioning system of the present invention is suitable for use in various vehicles such as automobiles. Examples of vehicles include, but are not limited to, automobiles and trains. Examples of automobiles include, but are not limited to, gasoline-powered vehicles, diesel-powered vehicles, gas-fueled vehicles using CNG (compressed natural gas) or LNG (liquefied natural gas), fuel cell vehicles, electric vehicles, and plug-in hybrid vehicles. The vehicular air conditioning system according to the embodiment of the present invention is particularly suitable for use in vehicles without internal combustion engines, such as electric vehicles and trains. In the following description, an air conditioning system used in a vehicle will be used as an example, but it goes without saying that the present invention can also be used in various other facilities and products such as those described above.

[0020] 1A and 1B are schematic diagrams of an air conditioning system according to an embodiment of the present invention, showing the operating state in each operation mode. In particular, FIG. 1A shows the heating operation mode, and FIGS. 1B and 1C show the cooling operation modes. FIG. 2A is a schematic diagram of a cross section parallel to the direction in which cells of a heating unit used in an air conditioning system according to an embodiment of the present invention extend. FIG. 2B is a schematic diagram of a cross section taken along line a-a' in the heating unit of FIG. 2A. FIG. 3A is a schematic diagram of a cross section parallel to the direction in which cells of another heating unit used in an air conditioning system according to an embodiment of the present invention extend. FIG. 3B is a schematic diagram of a cross section taken along line b-b' in the heating unit of FIG. 3A.

[0021] The air conditioning system according to the embodiment of the present invention includes a heat pump cycle 10 and a heating unit 100. The air conditioning system may also include a control unit 110, an air conditioning duct 120, a ventilator 130, and an air mix door 140. Each of these components will be described in detail below.

[0022] (1. Heat pump cycle 10) The heat pump cycle 10 includes a refrigerant pipe 20 and a compressor 30 . The heat pump cycle 10 is not particularly limited in structure as long as it has these components, and any known structure can be adopted. For example, the heat pump cycle 10 can further include a condenser 40, an evaporator 50, an outdoor heat exchanger 60, expansion valves 70a and 70b, and shut-off valves 80a to 80e. The condenser 40 and the evaporator 50 are provided in an air conditioning duct 120.

[0023] The refrigerant pipe 20 is a component that allows refrigerant to circulate, and connects various components such as a compressor 30 and a condenser 40 . Compressor 30 is a component capable of compressing a refrigerant. Specifically, compressor 30 is driven by control unit 110 to compress the refrigerant and discharge the high-temperature, high-pressure refrigerant into condenser 40. It should be noted that a known device such as a gas-liquid separator may be provided upstream of the compressor 30.

[0024] Condenser 40 is a component that exchanges heat between the refrigerant and the air flowing through air conditioning duct 120. Specifically, when the heating operation mode is performed, condenser 40 is capable of dissipating heat using the high-temperature, high-pressure refrigerant flowing inside, and heats the air flowing through air conditioning duct 120 around condenser 40. The evaporator 50 is also a component that exchanges heat between the air circulating in the air conditioning duct 120 and the refrigerant. Specifically, when the cooling operation mode is performed, the evaporator 50 can absorb heat using the low-temperature, low-pressure refrigerant circulating inside, and cools the air flowing in the air conditioning duct 120 around the evaporator 50.

[0025] The outdoor heat exchanger 60 is a component that exchanges heat between outside air and a refrigerant. The outdoor heat exchanger 60 can absorb heat from outside air using a low-temperature, low-pressure refrigerant circulating inside, mainly during a heating operation mode, and vaporizes the refrigerant by absorbing heat from the outside air. Furthermore, the outdoor heat exchanger 60 can release heat to outside air using a high-temperature, high-pressure refrigerant circulating inside, mainly during a cooling operation mode, and cools the refrigerant by releasing heat to the outside air.

[0026] The expansion valves 70a and 70b are throttle valves whose opening degrees can be adjusted by the control unit 110. In particular, when the heating operation mode is being performed, the expansion valve 70a reduces the pressure of the refrigerant discharged from the condenser 40, causes it to expand, and then discharges the low-temperature, low-pressure refrigerant to the outdoor heat exchanger 60. In addition, when the cooling operation mode is being performed, the expansion valve 70b reduces the pressure of the refrigerant from the outdoor heat exchanger 60, causes it to expand, and then discharges the low-temperature, low-pressure refrigerant to the evaporator 50.

[0027] The shutoff valves 80a to 80e are provided to control the flow path of the refrigerant. The control unit 110 controls the shutoff valves 80a to 80e to open and close.

[0028] (2.Heating section 100) The heating unit 100 is provided on the refrigerant pipe 20 on the upstream side, downstream side, or both of the upstream and downstream sides of the compressor 30, based on the flow direction of the refrigerant. For example, in the air conditioning system shown in Figures 1A and 1B, the heating unit 100 can be provided on the refrigerant pipe 20 between the compressor 30 and the condenser 40 (e.g., position P1), between the compressor 30 and the evaporator 50 or the outdoor heat exchanger 60 (e.g., position P2), or on both of the upstream and downstream sides (e.g., positions P1 and P2). By providing the heating unit 100 at such a position, the refrigerant can be heated quickly in cold weather, thereby improving initial heating performance.

[0029] The heating section 100 comprises a honeycomb structure having an outer peripheral wall 101 and partition walls 105 disposed inside the outer peripheral wall 101 and defining a plurality of cells 104 extending from a first end face 102 to a second end face 103, with at least the partition walls 105 being made of a material having PTC properties. By using the heating section 100 having such a honeycomb structure, it is possible to reduce power consumption compared to conventional sheath heaters (electric heaters).

[0030] The method of providing the heating unit 100 on the refrigerant pipe 20 is not particularly limited, and may be an indirect heating method in which the heating unit 100 is disposed around the refrigerant pipe 20 and the refrigerant is indirectly heated by heating the refrigerant pipe 20, or a direct heating method in which the heating unit 100 is disposed midway through the refrigerant pipe 20 and the refrigerant is directly heated. Of these methods, the direct heating method is preferred from the viewpoint of heating efficiency.

[0031] In the case of the indirect heating method, for example, as shown in Figures 2A and 2B, the periphery of the refrigerant pipe 20 can be covered with a honeycomb structure. In this case, the honeycomb structure may further have an inner peripheral wall 106, and the inner peripheral wall 106 may be provided so as to be in contact with the refrigerant pipe 20. Alternatively, although not shown, the outer peripheral wall 101 of the honeycomb structure may be provided so as to be in contact with the refrigerant pipe 20. In this case, the honeycomb structure does not need to have the inner peripheral wall 106. Alternatively, the honeycomb structure may be configured so that the honeycomb structure and the refrigerant pipe 20 are not in contact with each other, and air heated by the honeycomb structure is brought into contact with the refrigerant pipe 20.

[0032] 3A and 3B, in the case of the direct heating method, a heating unit 100 including a honeycomb structure and an outer tubular member 109 covering the periphery of an outer peripheral wall 101 of the honeycomb structure may be disposed midway along the refrigerant pipe 20, so that the refrigerant flows through the cells 104. In this case, the method for connecting the refrigerant pipe 20 and the heating unit 100 is not particularly limited, and the outer tubular member 109 and the refrigerant pipe 20 may be connected by any known method such as bolts or welding.

[0033] The shape of the honeycomb structure is not particularly limited. For example, the outer shape of a cross section perpendicular to the extension direction of the cells 104 of the honeycomb structure can be a polygon such as a quadrangle (rectangle, square), pentagon, hexagon, heptagon, or octagon, a circle, or an oval shape (egg, ellipse, oval, rounded rectangle, etc.). The end faces (first end face 102 and second end face 103) have the same shape as the cross section. When the cross section and end faces are polygonal, the corners may be chamfered.

[0034] The shape of the cells 104 is not particularly limited, but may be a polygon such as a square, pentagon, hexagon, heptagon, or octagon, a circle, or an oval in a cross section perpendicular to the extension direction of the cells 104 of the honeycomb structure. These shapes may be a single shape or a combination of two or more shapes. Among these shapes, a square or a hexagon is preferable.

[0035] The honeycomb structure may be a honeycomb bonded body having a plurality of honeycomb segments and a bonding layer bonding the outer peripheral side surfaces of the plurality of honeycomb segments together. By using the honeycomb bonded body, it is possible to increase the total cross-sectional area of the cells 104, which is important for ensuring the air flow rate, while suppressing the occurrence of cracks. The bonding layer can be formed using a bonding material. The bonding material is not particularly limited, but a ceramic material with a solvent such as water added to form a paste can be used. The bonding material may contain a material having PTC properties, or may contain the same material as the outer peripheral wall 101 and the partition walls 105. In addition to the role of bonding the honeycomb segments together, the bonding material can also be used as an outer peripheral coating material after bonding the honeycomb segments.

[0036] The thickness of the outer peripheral wall 101 and the inner peripheral wall 106 is not particularly limited, but is preferably 0.2 to 0.8 mm. By making the thickness of the outer peripheral wall 101 and the inner peripheral wall 106 0.2 mm or more, the strength of the honeycomb structure can be ensured. Furthermore, by making the thickness of the outer peripheral wall 101 and the inner peripheral wall 106 0.8 mm or less, the electrical resistance can be increased and the initial current can be suppressed. Here, in this specification, the thickness of the outer peripheral wall 101 refers to the length in the normal direction from the boundary between the outer peripheral wall 101 and the outermost cell 104 or partition wall 105 to the outer surface of the honeycomb structure in a cross section perpendicular to the extension direction of the cells 104. Similarly, the thickness of the inner peripheral wall 106 refers to the length in the normal direction from the boundary between the inner peripheral wall 106 and the innermost cell 104 or partition wall 105 to the inner surface of the honeycomb structure in the same cross section.

[0037] The thickness of the partition walls 105 is not particularly limited, but is preferably 0.01 to 0.3 mm, more preferably 0.02 to 0.2 mm, and even more preferably 0.03 to 0.1 mm. By controlling the thickness of the partition walls 105 within such a range, the strength of the honeycomb structure can be ensured. Here, in this specification, the thickness of the partition walls 105 refers to the length of a line segment that crosses the partition walls 105 when the line segment connects the centers of gravity of adjacent cells 104 in a cross section perpendicular to the extension direction of the cells 104. The thickness of the partition walls 105 refers to the average value of the thicknesses of all the partition walls 105.

[0038] The cell density is not particularly limited, but is preferably 30 to 100 cells / cm. 2 , more preferably 35 to 70 cells / cm 2 , and more preferably 40 to 65 cells / cm 2 By controlling the cell density within this range, the strength of the honeycomb structure can be ensured. Here, in this specification, cell density is a value obtained by dividing the number of cells by the area of one end face (first end face 102 or second end face 103) of the honeycomb structure (the total area of the partition walls 105 and cells 104 excluding the outer wall 101).

[0039] The cell pitch is not particularly limited, but is preferably 1.0 to 2.0 mm, more preferably 1.2 to 1.8 mm, and even more preferably 1.3 to 1.6 mm or more. By controlling the cell pitch within such a range, the strength of the honeycomb structure can be ensured. Here, in this specification, the cell pitch refers to a value obtained by the following calculation. First, the area per cell is calculated by dividing the area of one end face (first end face 102 or second end face 103) of the honeycomb structure (the total area of the partition walls 105 and cells 104 excluding the outer peripheral wall 101) by the number of cells. Next, the square root of the area per cell is calculated, and this is defined as the cell pitch.

[0040] The length of the honeycomb structure in the direction in which the cells 104 extend and the cross-sectional area perpendicular to the flow path direction are not particularly limited and may be adjusted according to the required size of the heating unit 100. For example, when the honeycomb structure is used in a compact heating unit 100 while ensuring a predetermined function, the length of the honeycomb structure in the direction in which the cells 104 extend is 2 to 20 mm, and the cross-sectional area perpendicular to the direction is 10 cm. 2The upper limit of the cross-sectional area perpendicular to the extension direction of the cells 104 is not particularly limited, but may be, for example, 300 cm 2 is.

[0041] The partition walls 105 constituting the honeycomb structure are made of a material that can generate heat when electricity is passed through them, specifically, a material having PTC characteristics. If necessary, the outer peripheral wall 101 and the inner peripheral wall 106 may also be made of a material having PTC characteristics, like the partition walls 105. With this configuration, it is possible to heat the refrigerant flowing through the refrigerant pipes 20 by heat transfer from the heat-generating partition walls 105 (and the outer peripheral wall 101 and the inner peripheral wall 106, if necessary). Furthermore, materials having PTC characteristics have the property that, when the temperature rises and exceeds the Curie point, the resistance value rises rapidly, making it difficult for electricity to flow. Therefore, when the partition walls 105 reach a high temperature, the current flowing through them is limited, thereby suppressing excessive heat generation in the honeycomb structure.

[0042] From the viewpoint of obtaining appropriate heat generation, the lower limit of the volume resistivity at 25°C of a material having PTC characteristics is preferably 0.5 Ω·cm or more, more preferably 1 Ω·cm or more, and even more preferably 5 Ω·cm or more. From the viewpoint of generating heat at a low driving voltage, the upper limit of the volume resistivity at 25°C of a material having PTC characteristics is preferably 30 Ω·cm or less, more preferably 18 Ω·cm or less, and even more preferably 16 Ω·cm or less. In this specification, the volume resistivity at 25°C of a material having PTC characteristics is measured in accordance with JIS K6271:2008.

[0043] From the viewpoint of being able to generate heat when electrically applied and having PTC properties, it is preferable that the material having PTC properties be mainly composed of barium titanate (BaTiO3). Furthermore, this material is more preferably a ceramic composed of a material mainly composed of barium titanate (BaTiO3)-based crystal particles in which part of the Ba has been substituted with a rare earth element. In this specification, the term "main component" refers to a component that accounts for more than 50 mass% of the total components. The content of BaTiO3-based crystal particles can be determined by fluorescent X-ray analysis. Other crystal particles can also be measured using the same method.

[0044] The composition formula of BaTiO3-based crystal particles in which part of Ba is replaced by rare earth elements is (Ba 1-x A x )TiO3, where A represents one or more rare earth elements and 0.0001≦x≦0.010. A is not particularly limited as long as it is a rare earth element, but is preferably one or more selected from the group consisting of La, Ce, Pr, Nd, Eu, Gd, Dy, Ho, Er, Y, and Yb, and more preferably La. x is preferably 0.001 or more, more preferably 0.0015 or more, from the viewpoint of preventing the electrical resistance at room temperature from becoming too high. On the other hand, x is preferably 0.009 or less, from the viewpoint of preventing the electrical resistance at room temperature from becoming too high due to insufficient sintering. The content of BaTiO3-based crystal particles in the ceramic, in which Ba is partially substituted with a rare earth element, is not particularly limited as long as it is an amount that serves as the main component, but is preferably 90 mass% or more, more preferably 92 mass% or more, and even more preferably 94 mass% or more. The upper limit of the content of BaTiO3-based crystal particles is not particularly limited, but is generally 99 mass%, preferably 98 mass%. The content of these BaTiO3-based crystal particles can be measured by fluorescent X-ray analysis. Other crystal particles can also be measured in the same manner.

[0045] From the viewpoint of reducing the environmental load, it is desirable that the material having PTC characteristics be substantially free of lead (Pb). Specifically, the Pb content of the material having PTC characteristics is preferably 0.01% by mass or less, more preferably 0.001% by mass or less, and even more preferably 0% by mass. In addition, the Pb content of the material having PTC characteristics, calculated as PbO, is preferably less than 0.03% by mass, more preferably less than 0.01% by mass, and even more preferably 0% by mass. The lead content can be determined by ICP-MS (inductively coupled plasma mass spectrometry).

[0046] The Curie point of the material having PTC characteristics is preferably in the temperature range where the resistance value becomes more than twice the resistance at room temperature (25°C). If the Curie point is in this temperature range, the current flowing through the honeycomb structure is limited when the honeycomb structure becomes hot, so that excessive heat generation in the heating unit 100 is efficiently suppressed. From the viewpoint of efficient heating of the refrigerant, the lower limit of the Curie point of the material having PTC properties is preferably 80° C. or higher, more preferably 100° C. or higher, even more preferably 110° C. or higher, and particularly preferably 125° C. or higher. From the viewpoint of safety as a component of an air conditioning system, the upper limit of the Curie point is preferably 200° C. or lower, more preferably 190° C. or lower, even more preferably 180° C. or lower, and particularly preferably 150° C. or lower.

[0047] The Curie point of a material with PTC properties can be adjusted by changing the type and amount of the shifter added. For example, the Curie point of barium titanate (BaTiO3) is approximately 120°C, but by substituting part of the Ba and Ti with one or more of Sr, Sn, and Zr, the Curie point can be shifted to a lower temperature.

[0048] In this specification, the Curie point is measured by the following method: A sample is attached to a sample holder for measurement and placed in a measurement tank (e.g., MINI-SUBZERO MC-810P, manufactured by ESPEC Corporation), and the change in the sample's electrical resistance with respect to temperature change when the temperature is raised from 10°C is measured using a DC resistance meter (e.g., multimeter 3478A, manufactured by YOKOGAWA HEWLETT PACKARD, LTD.). The Curie point is determined as the temperature at which the resistance value is twice the resistance value at room temperature (20°C) based on the electrical resistance-temperature plot obtained by the measurement.

[0049] As shown in Fig. 2A, the honeycomb structure may include a pair of electrodes 107, 108. The pair of electrodes 107, 108 may be provided on the first end face 102 and the second end face 103, as shown in Fig. 2A. The pair of electrodes 107, 108 may also be provided on the outer peripheral wall 101 parallel to the direction in which the cells 104 extend. By applying a voltage between the pair of electrodes 107 and 108, it becomes possible to cause the honeycomb structure to generate heat by Joule heat.

[0050] The pair of electrodes 107, 108 is not particularly limited, and may be made of, for example, a metal or alloy containing at least one selected from Cu, Ag, Al, Ni, and Si. Alternatively, an ohmic electrode capable of making ohmic contact with the outer peripheral wall 101 or the partition wall 105, which have PTC characteristics, may be used. The ohmic electrode may contain, for example, at least one selected from Al, Au, Ag, and In as a base metal and at least one selected from Ni, Si, Zn, Ge, Sn, Se, and Te as a dopant for n-type semiconductors. The pair of electrodes 107, 108 may have a single-layer structure or a stacked structure of two or more layers. When the pair of electrodes 107, 108 have a stacked structure of two or more layers, the materials of the layers may be the same or different.

[0051] The thickness of the pair of electrodes 107, 108 can be set appropriately depending on the method for forming the pair of electrodes 107, 108. Examples of methods for forming the pair of electrodes 107, 108 include metal deposition methods such as sputtering, vapor deposition, electrolytic deposition, and chemical deposition. The pair of electrodes 107, 108 can also be formed by applying an electrode paste and then baking it, or by thermal spraying. Furthermore, the pair of electrodes 107, 108 may be formed by joining metal plates or alloy plates.

[0052] The thickness of the pair of electrodes 107, 108 is preferably about 5 to 30 μm for baking of an electrode paste, about 100 to 1000 nm for dry plating such as sputtering and vapor deposition, about 10 to 100 μm for thermal spraying, and about 5 to 30 μm for wet plating such as electrolytic deposition and chemical deposition. Furthermore, when joining metal or alloy plates, the thickness is preferably about 5 to 100 μm.

[0053] The honeycomb structure may further include terminals connected to the pair of electrodes 107 and 108. By providing the terminals, connection to an external power source becomes easy. The material of the terminal is not particularly limited, but may be, for example, a metal. As the metal, a single metal or an alloy may be used, but from the viewpoints of corrosion resistance, electrical resistivity, and linear expansion coefficient, an alloy containing at least one selected from the group consisting of Cr, Fe, Co, Ni, Cu, Al, and Ti is preferable, and stainless steel, an Fe-Ni alloy, or phosphor bronze is more preferable. The thickness of the terminal is not particularly limited, but is, for example, 0.01 to 10 mm, typically 0.05 to 5 mm. The method of connecting the terminal and the pair of electrodes 107, 108 is not particularly limited as long as they are electrically connected, and they can be connected by, for example, diffusion bonding, a mechanical pressure mechanism, welding, or the like.

[0054] There are no particular limitations on the method for manufacturing the honeycomb structure constituting the heating part 100, and it can be carried out in accordance with a known method. A typical example of manufacturing the honeycomb structure will be described below. The method for manufacturing a honeycomb structure includes a molding step and a firing step. In the molding step, a clay containing ceramic raw materials including BaCO3 powder, TiO2 powder, and powder of a rare earth nitrate or hydroxide is molded to produce a honeycomb molded body with a relative density of 60% or more. The ceramic raw material can be obtained by dry mixing each powder to obtain a desired composition. The clay can be obtained by adding a dispersion medium, a binder, a plasticizer, and a dispersant to a ceramic raw material and kneading the mixture. The clay may contain additives such as a sifter, a metal oxide, a property improver, and a conductive powder, as needed. The blending amount of components other than the ceramic raw materials is not particularly limited as long as it is an amount that allows the relative density of the honeycomb formed body to be 60% or more.

[0055] Here, in this specification, the "relative density of the honeycomb formed body" means the ratio of the density of the honeycomb formed body to the true density of the entire ceramic raw material. Specifically, it can be calculated by the following formula. Relative density (%) of honeycomb formed body = Density of honeycomb formed body (g / cm 3 ) / true density of the entire ceramic raw material (g / cm 3 ) x 100 The density of the honeycomb formed body can be measured by the Archimedes method using pure water as a medium. The true density of the entire ceramic raw material is calculated by multiplying the total mass (g) of each raw material by the total actual volume (cm) of each raw material. 3 ) can be calculated by dividing by

[0056] Examples of the dispersion medium include water and a mixed solvent of water and an organic solvent such as alcohol, with water being particularly preferred.

[0057] Examples of binders include organic binders such as methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. It is particularly preferable to use a combination of methyl cellulose and hydroxypropoxyl cellulose. While one binder may be used alone or two or more binders may be used in combination, it is preferable that the binder does not contain an alkali metal element.

[0058] Examples of the plasticizer include polyoxyalkylene alkyl ether, polycarboxylic acid polymer, and alkyl phosphate ester.

[0059] The dispersant may be a surfactant such as polyoxyalkylene alkyl ether, ethylene glycol, dextrin, fatty acid soap, polyalcohol, etc. The dispersant may be used alone or in combination of two or more.

[0060] The honeycomb formed body can be produced by extrusion molding of a clay. During extrusion molding, a die having a desired overall shape, cell shape, thickness of each portion, cell density, etc. can be used.

[0061] The relative density of the honeycomb formed body obtained by extrusion molding is 60% or more, preferably 65% or more. By controlling the relative density of the honeycomb formed body within this range, it is possible to densify the honeycomb formed body and reduce its electrical resistance at room temperature. The upper limit of the relative density of the honeycomb formed body is not particularly limited, but is generally 80%, preferably 75%.

[0062] The honeycomb molded body can be dried before the firing step. The drying method is not particularly limited, and for example, a conventionally known drying method such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying, etc. Among these, a drying method that combines hot air drying with microwave drying or dielectric drying is preferred because it can dry the entire molded body quickly and uniformly.

[0063] The firing step involves holding the temperature at 1150 to 1250°C, then raising the temperature to a maximum temperature of 1360 to 1430°C at a rate of 20 to 600°C / hour, and holding the temperature for 0.5 to 10 hours. By holding the honeycomb formed body at a maximum temperature of 1360 to 1430°C for 0.5 to 10 hours, a honeycomb structure containing as its main component BaTiO3-based crystal particles in which part of Ba has been substituted with a rare earth element can be obtained. Furthermore, by maintaining the temperature at 1150 to 1250°C, Ba2TiO4 crystal particles generated during the firing process are easily removed, and the honeycomb structure can be densified. Furthermore, by setting the heating rate from 1150 to 1250°C to the maximum temperature of 1360 to 1430°C at 20 to 600°C / hour, 1.0 to 10.0 mass% of Ba6Ti 17 O 40 Crystal grains can be formed in the honeycomb structure.

[0064] The holding time at 1150 to 1250°C is not particularly limited, but is preferably 0.5 to 10 hours. By holding for such a time, Ba2TiO4 crystal particles formed during the firing process can be stably and easily removed.

[0065] The firing step preferably includes holding the mixture at 900 to 950°C for 0.5 to 5 hours during temperature increase. Holding the mixture at 900 to 950°C for 0.5 to 5 hours efficiently decomposes BaCO3, making it easier to obtain a honeycomb structure having a predetermined composition.

[0066] Before the firing step, a degreasing step may be carried out to remove the binder. The degreasing step is preferably carried out in an air atmosphere to completely decompose the organic components. Furthermore, the firing step is preferably carried out in an air atmosphere from the viewpoint of controlling electrical properties and reducing manufacturing costs. The firing furnace used in the firing step and degreasing step is not particularly limited, but an electric furnace, a gas furnace, or the like can be used.

[0067] A pair of electrodes 107, 108 are formed on the honeycomb structure thus obtained. The pair of electrodes 107, 108 can be formed by a metal deposition method such as sputtering, vapor deposition, electrolytic deposition, or chemical deposition. The pair of electrodes 107, 108 can also be formed by applying an electrode paste and then baking it. Furthermore, the pair of electrodes 107, 108 can also be formed by thermal spraying. The pair of electrodes 107, 108 may be formed of a single layer, or may be formed of multiple electrode layers with different compositions. Representative methods for forming the pair of electrodes 107, 108 will be described below.

[0068] First, an electrode slurry containing an electrode material, an organic binder, and a dispersion medium is prepared and applied to the first end surface 102 or the second end surface 103 of the honeycomb structure. The dispersion medium can be water, an organic solvent (e.g., toluene, xylene, ethanol, n-butanol, ethyl acetate, butyl acetate, terpineol, dihydroterpineol, Texanol, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether), or a mixture thereof. Excess slurry on the outer periphery of the honeycomb structure is removed by blowing and wiping. Thereafter, the slurry is dried to form a pair of electrodes 107, 108 on the first end surface 102 or the second end surface 103 of the honeycomb structure. Drying can be performed while heating the heater element to a temperature of, for example, about 120 to 600°C. The series of steps of coating, removing the slurry, and drying may be carried out only once, but by repeating the steps multiple times, a pair of electrodes 107, 108 of a desired thickness can be provided.

[0069] Next, when providing terminals, the terminals are placed at predetermined positions of the pair of electrodes 107, 108, and the pair of electrodes 107, 108 are connected to the terminals. The above-mentioned methods can be used to connect the pair of electrodes 107, 108 to the terminals.

[0070] (3. Control Unit 110) The control unit 110 controls the heat pump cycle 10 and the heating unit 100 according to the operation mode. The control unit 110 is electrically connected to the heat pump cycle 10 and the heating unit 100. Specifically, the control unit 110 is electrically connected to the shutoff valves 80a to 80e of the heat pump cycle 10, and can control the refrigerant flow path by opening and closing the shutoff valves 80a to 80e. The control unit 110 is also electrically connected to the expansion valves 70a and 70b of the heat pump cycle 10, and can control the degree of decompression of the refrigerant by adjusting the opening degrees of the expansion valves 70a and 70b. Furthermore, the control unit 110 is connected to a power source for applying a voltage to the pair of electrodes 107 and 108 of the heating unit 100, and can adjust the heating state of the honeycomb structure by controlling the power source. The power source is not particularly limited, and a battery or the like can be used.

[0071] The control unit 110 is electrically connected to the heat pump cycle 10 and the heating unit 100 as well as the ventilator 130, the air mix door 140, and the like, and can control these.

[0072] The control unit 110 is not particularly limited, but is generally an ECU (Engine (electronic) Control Unit). The ECU includes a CPU that executes various arithmetic processes, a ROM that stores programs and data required for the control, a RAM that temporarily stores the results of the CPU calculations, and an input / output port for inputting and outputting signals to and from the outside.

[0073] (4. Ventilator 130) The ventilator 130 is provided to circulate air through the air conditioning duct 120. There are no particular limitations on the ventilator 130, and any known ventilator can be used. The position of the ventilator 130 is not particularly limited, and for example, it can be provided upstream of the condenser 40 or the evaporator 50. However, the ventilator 130 may also be provided downstream of the condenser 40 or the evaporator 50.

[0074] (5. Air Mix Door 140) Air mix door 140 is configured to rotate between a heating position in air conditioning duct 120, where it opens a heating path leading to condenser 40, and a cooling position, where it opens a cooling path that bypasses condenser 40. By rotating air mix door 140 between the heating position and the cooling position, it is possible to adjust the ratio of air passing through condenser 40 and air bypassing condenser 40, thereby adjusting the temperature of the air flowing into the vehicle cabin.

[0075] In the air conditioning system according to the embodiment of the present invention, the operation modes of the heat pump cycle 10 can include a heating operation mode and a cooling operation mode. The operation mode of the heat pump cycle 10 can be selected in response to a switch operation by the driver or temperature changes detected by various detectors.

[0076] (A) Heating operation mode 1A, in the heating operation mode, shutoff valves 80a to 80c are opened and shutoff valves 80d and 80e are closed, thereby forming a flow path in which the refrigerant flows sequentially through compressor 30, condenser 40, expansion valve 70a, and outdoor heat exchanger 60. In FIG. 1A, the flow path through which the refrigerant flows in this heating operation mode is indicated by a thick line. This heating operation mode involves compressing a refrigerant by compressor 30 and introducing the refrigerant discharged from compressor 30 into condenser 40 to heat the air. That is, the refrigerant compressed by compressor 30 enters condenser 40 as a high-temperature, high-pressure refrigerant, and releases heat through heat exchange with the air circulating in air conditioning duct 120 (heating the air). The refrigerant leaving condenser 40 is decompressed and expanded by expansion valve 70a to become a low-temperature, low-pressure refrigerant, and then exchanges heat with outside air in outdoor heat exchanger 60 to absorb heat before returning to compressor 30. When this heating operation mode is performed, the air circulating in the air conditioning duct 120 is heated by the condenser 40, and the heated air flows into the passenger compartment. The temperature of the air flowing into the passenger compartment can be adjusted by controlling the opening degree of the air mix door 140.

[0077] Furthermore, at the start of this heating operation mode, the control unit 110 controls the heating unit 100 to apply a voltage to the honeycomb structure constituting the heating unit 100 to heat the refrigerant. By controlling in this manner, even if the temperature of the refrigerant in the heat pump cycle 10 is low in cold weather, the refrigerant is quickly heated, thereby improving the initial heating performance.

[0078] (B) First cooling operation mode 1B, in the first cooling operation mode, shutoff valves 80a, 80d, and 80e are opened and shutoff valves 80b and 80c are closed, thereby forming a flow path through which the refrigerant flows sequentially through the compressor 30, the outdoor heat exchanger 60, the expansion valve 70b, and the evaporator 50. In FIG. 1B, the flow path through which the refrigerant flows in this cooling operation mode is indicated by a thick line. This cooling operation mode involves introducing refrigerant that has been decompressed and expanded by expansion valve 70b into evaporator 50 to cool the air. That is, the refrigerant that has been compressed by compressor 30 to a high temperature and pressure is cooled by exchanging heat with outside air in outdoor heat exchanger 60 and releasing heat. The refrigerant that has left outdoor heat exchanger 60 is decompressed and expanded by expansion valve 70b, becoming a low temperature and low pressure refrigerant that enters evaporator 50 and exchanges heat with the air circulating inside air conditioning duct 120 to absorb heat (cool the air). The refrigerant that has left evaporator 50 returns to compressor 30. When this cooling operation mode is performed, the air circulating in the air conditioning duct 120 is cooled by the evaporator 50, and the cooled air flows into the passenger compartment. This cooling operation mode is particularly useful when it is desired to rapidly cool the passenger compartment (strong cooling operation mode).

[0079] (C) Second cooling operation mode 1C, in the second cooling operation mode, shutoff valves 80a, 80c, and 80e are opened and shutoff valves 80b and 80d are closed, thereby forming a flow path in which the refrigerant flows sequentially through compressor 30, condenser 40, expansion valve 70a, outdoor heat exchanger 60, expansion valve 70b, and evaporator 50. In FIG. 1C, the flow path through which the refrigerant flows in this cooling operation mode is indicated by a thick line. In the cooling operation mode, the refrigerant flow path further includes a condenser 40 and an expansion valve 70a downstream of the compressor 30. In the cooling operation mode, the cooling of the air by the evaporator 50 and the heating of the air by the condenser 40 can be adjusted by controlling the opening degree of the air mix door 140, so that the air temperature can be controlled to an optimum temperature. [Explanation of symbols]

[0080] 10 Heat pump cycle 20 Refrigerant piping 30 Compressor 40 capacitor 50 Evaporator 60 Outdoor heat exchanger 70a, 70b Expansion valve 80a, 80b, 80c, 80d, 80e Shut-off valves 100 Heating section 101 Peripheral wall 102 First end surface 103 Second end face 104 cells 105 Bulkhead 106 Inner wall 107,108 electrode 110 control section 120 Air conditioning duct 130 Ventilator 140 Air Mix Door

Claims

1. An air conditioning system including a heat pump cycle having a refrigerant pipe through which a refrigerant can circulate and a compressor capable of compressing the refrigerant, a heating unit capable of heating the refrigerant is provided in the refrigerant pipe on the upstream side, downstream side, or both of the upstream side and downstream side of the compressor with respect to the flow direction of the refrigerant; The heating section has an outer peripheral wall and partition walls arranged inside the outer peripheral wall and defining a plurality of cells extending from a first end face to a second end face, and the air conditioning system is equipped with a honeycomb structure in which at least the partition walls are made of a material having PTC properties.

2. a control unit that controls the heat pump cycle and the heating unit; The air conditioning system according to claim 1 , wherein the control unit performs control so as to apply a voltage to the honeycomb structure to heat the refrigerant when the heating operation mode of the heat pump cycle starts.

3. The heat pump cycle further includes a condenser that performs heat exchange between the air circulating in the air conditioning duct and the refrigerant, The air conditioning system according to claim 2 , wherein the heating operation mode includes compressing the refrigerant with the compressor and introducing the refrigerant discharged from the compressor into the condenser to heat the air.

4. The heat pump cycle includes: an evaporator that performs heat exchange between the air circulating in the air conditioning duct and the refrigerant; an outdoor heat exchanger that exchanges heat between outside air and the refrigerant; The air conditioning system of claim 3 further comprising:

5. The air conditioning system according to claim 4 , wherein the heating unit is provided in the refrigerant pipe between the compressor and the condenser, between the compressor and the evaporator or the outdoor heat exchanger, or in both of these refrigerant pipes.

6. 6. The air conditioning system according to claim 1, wherein the material having PTC properties is based on barium titanate.

7. The air conditioning system according to any one of claims 1 to 5, wherein the air conditioning system is for a vehicle.

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