Air conditioning system

Abstract

The invention provides an air conditioning system capable of suppressing power consumption and improving initial heating performance. An air conditioning system is provided with a heat pump cycle (10) having a refrigerant pipe (20) through which a refrigerant can circulate, and a compressor (30) which can compress the refrigerant. A heating unit (100) capable of heating the refrigerant is provided on the refrigerant pipe (20) on the upstream side, the downstream side, or both of the compressor (30) with respect to the flow direction of the refrigerant. The heating unit (100) is provided with a honeycomb structure having an outer peripheral wall (101) and partition walls (105) disposed on the inner side of the outer peripheral wall (101) and defining a plurality of cells (104) extending from a first end surface (102) to a second end surface (103), and at least the partition walls (105) are made of a material having PTC characteristics.

Description

Technical Field

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

[0002] There is known an air conditioning system that can perform cooling and heating using a heat pump cycle. Since this air conditioning system has advantages such as power saving, it is also used in vehicles such as battery electric vehicles (BEVs). The heat pump cycle has a configuration in which components such as a compressor, a condenser, an evaporator, and an expansion valve are connected in a ring shape through a refrigerant pipe, and by utilizing the vaporization heat and condensation heat of the refrigerant, cooling and heating can be performed.

[0003] However, an air conditioning system using a heat pump cycle has the following problem: Since the outside air is converted into heat, the initial heating performance decreases (the start of heating is delayed) in cold weather. Specifically, in cold weather, the temperature of the refrigerant flowing through the heat pump cycle is low, so when heating starts, it is difficult for the temperature and pressure of the refrigerant to rise. As a result, the start of heating is delayed, and it takes a certain amount of time to supply warm air.

[0004] Therefore, in order to solve the above problems, Patent Document 1 proposes an air conditioning system (vehicle air conditioning device) that controls to reduce the air volume supplied to the in-vehicle heat exchanger that becomes a radiator at the start of heating. In addition, Patent Document 2 proposes an air conditioning system (vehicle air conditioning device) that increases the heating amount of the refrigerant heater to heat the refrigerant in order to accelerate the start of heating.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014 - 24371

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2014 - 131914 Summary of the Invention

[0009] However, regarding the air conditioning system of Patent Document 1, although it is easy to reduce the amount of heat exchange between the refrigerant ejected from the compressor and the outside air when flowing through the radiator (in-vehicle heat exchanger) by reducing the air volume supplied to the radiator at the start of heating, and thus increase the temperature of the refrigerant, since the refrigerant cannot be heated, it cannot be said that the initial heating performance is sufficient.

[0010] In addition, regarding the air conditioning system of Patent Document 2, since a refrigerant heater composed of a sheathed heater (electric heater) is used to heat the refrigerant, the power consumption increases. Therefore, for example, when this air conditioning system is used in an electric vehicle, there is a problem that the cruising range is significantly reduced due to energy loss.

[0011] The present invention is implemented to solve the above problems, and its object is to provide an air conditioning system capable of suppressing power consumption and improving initial heating performance.

[0012] The inventors of the present invention have intensively studied an air conditioning system using a heat pump cycle, and as a result, they have found that by providing a prescribed heating unit in a refrigerant pipe through which the refrigerant flows to heat the refrigerant, the above problems can be solved, and thus the present invention has been completed. That is, the present invention is exemplified as follows.

[0013] [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.

[0014] The air conditioning system is characterized in that

[0015] Based on the flow direction of the refrigerant, a heating unit capable of heating the refrigerant is provided in the refrigerant pipe on the upstream side, downstream side, or both sides of the compressor.

[0016] The heating unit includes a honeycomb structure having an outer peripheral wall and partition walls. The partition walls are disposed inside the outer peripheral wall and define a plurality of compartments extending from a first end face to a second end face. At least the partition walls are made of a material having PTC characteristics.

[0017] [2] The air conditioning system according to [1], characterized in that

[0018] The air conditioning system further includes a control unit that controls the heat pump cycle and the heating unit.

[0019] The control unit includes: at the start of the heating operation mode of the heat pump cycle, controlling to apply a voltage to the honeycomb structure to heat the refrigerant.

[0020] [3] The air conditioning system according to [2], characterized in that

[0021] The heat pump cycle further includes a condenser that performs heat exchange between the air flowing in the air conditioning passage and the refrigerant.

[0022] The heating operation mode includes: compressing the refrigerant by the compressor, and introducing the refrigerant ejected from the compressor into the condenser to heat the air.

[0023] [4] The air conditioning system according to any one of [1] to [3], characterized in that

[0024] The heat pump cycle further includes:

[0025] An evaporator that performs heat exchange between the air flowing in the air conditioning passage and the refrigerant; and

[0026] An outdoor heat exchanger that performs heat exchange between the outside atmosphere and the refrigerant.

[0027] [5] The air conditioning system according to [4], characterized in that

[0028] 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 both.

[0029] [6] The air conditioning system according to any one of [1] to [5], characterized in that

[0030] The material having PTC characteristics has barium titanate as the main component.

[0031] [7] The air conditioning system according to any one of [1] to [6], characterized in that

[0032] The air conditioning system is for a vehicle.

[0033] Advantages of the Invention

[0034] According to the present invention, an air conditioning system capable of suppressing power consumption and improving initial heating performance can be provided. Brief Description of the Drawings

[0035] Figure 1A It is a schematic configuration diagram of a vehicle air conditioning system according to an embodiment of the present invention, and is a diagram showing the working state in the heating operation mode.

[0036] Figure 1B It is a schematic configuration diagram of a vehicle air conditioning system according to an embodiment of the present invention, and is a diagram showing the working state in the cooling operation mode.

[0037] Figure 1C It is a schematic configuration diagram of a vehicle air conditioning system according to an embodiment of the present invention, and is a diagram showing the working state in another cooling operation mode.

[0038] Figure 2A It is a schematic cross-sectional view parallel to the extending direction of the compartment of the heating part used in the air conditioning system according to an embodiment of the present invention.

[0039] Figure 2B It is Figure 2A a schematic cross-sectional view of line a-a' in the heating part of

[0040] Figure 3A It is a schematic cross-sectional view parallel to the extending direction of the compartment of another heating part used in the air conditioning system according to an embodiment of the present invention.

[0041] Figure 3B It is Figure 3A a schematic cross-sectional view of line b-b' in the heating part of

[0042] Symbol Explanation

[0043] 10... Heat pump cycle; 20... Refrigerant pipe; 30... Compressor; 40... Condenser; 50... Evaporator; 60... Outdoor heat exchanger; 70a, 70b... Expansion valve; 80a, 80b, 80c, 80d, 80e... Stop valve; 100... Heating part; 101... Outer peripheral wall; 102... First end face; 103... Second end face; 104... Compartment; 105... Partition wall; 106... Inner peripheral wall; 107, 108... Electrodes; 110... Control part; 120... Air conditioning passage; 130... Fan; 140... Air mixing door. Detailed Embodiment

[0044] The air conditioning system of the present invention includes a heat pump cycle, which has a refrigerant pipe capable of circulating refrigerant and a compressor capable of compressing the refrigerant. Based on the flow direction of the refrigerant, a heating part capable of heating the refrigerant is provided on the refrigerant pipe on the upstream side, downstream side, or both sides of the compressor. The heating part includes a honeycomb structure, which has an outer peripheral wall and partition walls. The partition walls are disposed inside the outer peripheral wall and partition to form a plurality of compartments extending from the first end face to the second end face. At least the partition walls are made of a material having PTC (Positive Temperature Coefficient) characteristics. Regarding the air conditioning system of the present invention, by adopting such a configuration, the refrigerant can be heated rapidly in cold weather, so the initial heating performance is improved. In addition, compared with the case of an air conditioning system that uses a conventional sheathed heater (electric heater) to heat the refrigerant, the air conditioning system of the present invention can suppress power consumption, so it can save energy, and especially when applied to an electric vehicle, the cruising range can be extended.

[0045] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. The present invention is not limited to the following embodiments, and it should be understood that: within the scope not departing from the gist of the present invention, solutions obtained by appropriately modifying and improving the following embodiments based on the general knowledge of those skilled in the art also fall within the scope of the present invention.

[0046] The air conditioning system of the present invention can be used in various devices, products, etc. that require air conditioning. For example, the air conditioning system of the present invention can be used in air conditioning devices, household appliances such as refrigerators and washing and drying machines, and various vehicles such as cars, which are adopted in offices, homes, etc. Among them, the air conditioning system of the present invention is preferably used in various vehicles such as cars. As the vehicle, there is no particular limitation, and cars and trams can be cited. As the car, there is no particular limitation, and gasoline cars, diesel cars, gas fuel cars using CNG (compressed natural gas) or LNG (liquefied natural gas), fuel cell vehicles, electric vehicles, and plug-in hybrid vehicles can be cited. The vehicle air conditioning system according to the embodiment of the present invention can be particularly preferably used in vehicles without an internal combustion engine such as electric vehicles and trams.

[0047] It should be noted that in the following description, the air conditioning system for vehicles is taken as an example for description. However, of course, it can also be used in various devices, products, etc. as described above.

[0048] Figure 1A and Figure 1B are schematic diagrams of the general configuration of the air conditioning system according to the embodiment of the present invention, and are diagrams showing the working states in each operation mode. In particular, Figure 1A is the heating operation mode, Figure 1B and Figure 1C are the cooling operation modes. Figure 2A is a schematic cross-sectional view parallel to the direction of compartment extension of the heating part used in the air conditioning system according to the embodiment of the present invention. Figure 2B is Figure 2A a schematic cross-sectional view of the a-a' line in the heating part of Figure 3A is a schematic cross-sectional view parallel to the direction of compartment extension of another heating part used in the air conditioning system according to the embodiment. Figure 3B is Figure 3A a schematic cross-sectional view of the b-b' line in the heating part of

[0049] The air conditioning system according to the embodiment of the present invention includes a heat pump cycle 10 and a heating part 100. In addition, the air conditioning system may include: a control part 110, an air conditioning passage 120, a ventilator 130, and an air mixing door 140.

[0050] Hereinafter, each of the above-described constituent elements will be described in detail.

[0051] (1. Heat pump cycle 10)

[0052] The heat pump cycle 10 includes a refrigerant pipe 20 and a compressor 30.

[0053] The heat pump cycle 10 only needs to have the above components, and its structure is not particularly limited, and a known structure can be adopted. For example, the heat pump cycle 10 may further include: a condenser 40, an evaporator 50, an outdoor heat exchanger 60, expansion valves 70a, 70b, and stop valves 80a to 80e. The condenser 40 and the evaporator 50 are provided in the air conditioning passage 120.

[0054] The refrigerant pipe 20 is a component through which the refrigerant can circulate, and connects various components such as the compressor 30 and the condenser 40.

[0055] The compressor 30 is a component that can compress the refrigerant. Specifically, the compressor 30 is driven by the control unit 110 to compress the refrigerant, and thereby ejects the high-temperature and high-pressure refrigerant into the condenser 40.

[0056] It should be noted that a known device such as a gas-liquid separator may be provided on the upstream side of the compressor 30.

[0057] The condenser 40 is a component that performs heat exchange between the air flowing in the air conditioning passage 120 and the refrigerant. Specifically, the condenser 40 can release heat through the high-temperature and high-pressure refrigerant flowing inside during the heating operation mode, and heat the air around the condenser 40 flowing in the air conditioning passage 120.

[0058] The evaporator 50 is also a component that performs heat exchange between the air flowing in the air conditioning passage 120 and the refrigerant. Specifically, the evaporator 50 can absorb heat through the low-temperature and low-pressure refrigerant flowing inside during the cooling operation mode, and cool the air around the evaporator 50 flowing in the air conditioning passage 120.

[0059] The outdoor heat exchanger 60 is a component that performs heat exchange between the outside atmosphere and the refrigerant. The outdoor heat exchanger 60 can mainly absorb heat from the outside atmosphere through the low-temperature and low-pressure refrigerant flowing inside during the heating operation mode, and vaporize the refrigerant by absorbing heat from the outside atmosphere. In addition, the outdoor heat exchanger 60 can mainly release heat to the outside atmosphere through the high-temperature and high-pressure refrigerant flowing inside during the cooling operation mode, and cool the refrigerant by releasing heat to the outside atmosphere.

[0060] 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 executed, the expansion valve 70a reduces the pressure of the refrigerant discharged from the condenser 40 to expand it, and then discharges the low-temperature and low-pressure refrigerant to the outdoor heat exchanger 60. In addition, when the cooling operation mode is executed, the expansion valve 70b reduces the pressure of the refrigerant from the outdoor heat exchanger 60 to expand it, and then discharges the low-temperature and low-pressure refrigerant to the evaporator 50.

[0061] The stop valves 80a to 80e are provided to control the refrigerant flow path. The stop valves 80a to 80e are controlled to open and close by the control unit 110.

[0062] (2. Heating unit 100)

[0063] Regarding the heating unit 100, based on the refrigerant flow direction, the refrigerant pipes 20 are provided on the upstream side, downstream side, or both sides of the compressor 30. For example, in Figure 1A and Figure 1B In the air conditioning system shown, the refrigerant pipes 20 can be provided between the compressor 30 and the condenser 40 (for example, position P1), between the compressor 30 and the evaporator 50 or the outdoor heat exchanger 60 (for example, position P2), or both (for example, position P1 and P2). By arranging the heating unit 100 at such positions, the refrigerant can be quickly heated in cold weather, so the initial heating performance is improved.

[0064] The heating unit 100 includes a honeycomb structure, which has an outer peripheral wall 101 and partition walls 105. The partition walls 105 are disposed inside the outer peripheral wall 101 and divide to form a plurality of compartments 104. The plurality of compartments 104 extend from the first end face 102 to the second end face 103, and at least the partition walls 105 are made of a material having PTC characteristics. By adopting the heating unit 100 with such a honeycomb structure, power consumption can be suppressed compared with the conventional sheathed heater (electrical heater).

[0065] As a method of arranging the heating unit 100 on the refrigerant pipe 20, there is no particular limitation. The indirect heating method of arranging the heating unit 100 around the refrigerant pipe 20 and indirectly heating the refrigerant through the heating of the refrigerant pipe 20 can be adopted, or the direct heating method of arranging the heating unit 100 in the middle of the refrigerant pipe 20 and directly heating the refrigerant can be adopted. Among these methods, from the perspective of heating efficiency, the direct heating method is preferred.

[0066] In the case of the indirect heating method, for example, as Figure 2A and Figure 2BAs shown, it can be set such that the periphery of the refrigerant pipe 20 is covered by a honeycomb structure. In this case, the honeycomb structure also has an inner peripheral wall 106, and the inner peripheral wall 106 can be set to contact the refrigerant pipe 20. Alternatively, although not shown, it can also be set such that the outer peripheral wall 101 of the honeycomb structure contacts the refrigerant pipe 20. In this case, the honeycomb structure may not have the inner peripheral wall 106. In addition, it can be configured such that instead of the honeycomb structure and the refrigerant pipe 20 contacting each other, the air heated by the honeycomb structure contacts the refrigerant pipe 20.

[0067] In the case of the direct heating method, for example, as Figure 3A and Figure 3B shown, the heating section 100 having a honeycomb structure and an outer cylinder member 109 covering the periphery of the outer peripheral wall 101 of the honeycomb structure can be arranged in the middle of the refrigerant pipe 20, and the refrigerant can flow in the compartment 104. In this case, as the connection method between the refrigerant pipe 20 and the heating section 100, there is no particular limitation, and the outer cylinder member 109 and the refrigerant pipe 20 can be connected by a known method such as bolts or welding.

[0068] The shape of the honeycomb structure is not particularly limited. For example, the outer shape of the cross-section of the honeycomb structure orthogonal to the direction in which the compartment 104 extends can be a polygon (rectangle, square), pentagon, hexagon, heptagon, octagon, etc., a circle, a shape with an arc (oval, ellipse, oblong, rounded rectangle, etc.), etc. It should be noted that the end faces (the first end face 102 and the second end face 103) have the same shape as this cross-section. In addition, in the case where the cross-section and the end face are polygons, the corners can be chamfered.

[0069] The shape of the compartment 104 is not particularly limited. In the cross-section of the honeycomb structure orthogonal to the direction of the compartment 104, it can be a polygon such as a quadrilateral, pentagon, hexagon, heptagon, octagon, a circle, or a shape with an arc. These shapes can be single or a combination of two or more. In addition, among these shapes, a quadrilateral or a hexagon is preferred.

[0070] The honeycomb structure can be a honeycomb bonded body having a plurality of honeycomb cells and a bonding layer that indirectly bonds the outer peripheral side surfaces of the plurality of honeycomb cells to each other. By using the honeycomb bonded body, the occurrence of cracking can be suppressed, and the total cross-sectional area of the compartment 104, which is very important for ensuring the air flow rate, can be increased.

[0071] It should be noted that a bonding material can be used to form a bonding layer. The bonding material is not particularly limited, and a material made by adding a solvent such as water to a ceramic material to form a paste-like material can be used. The bonding material may contain a material having PTC characteristics, or may contain the same material as the outer peripheral wall 101 and the partition wall 105. In addition to the function of bonding the honeycomb units to each other, the bonding material can also be used as an outer peripheral coating material after bonding the honeycomb units.

[0072] The thicknesses of the outer peripheral wall 101 and the inner peripheral wall 106 are not particularly limited, and are preferably 0.2 to 0.8 mm. By making the thicknesses 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. In addition, by making the thicknesses of the outer peripheral wall 101 and the inner peripheral wall 106 0.8 mm or less, the resistance can be increased to suppress the initial current.

[0073] Here, in this specification, the thickness of the outer peripheral wall 101 means: in a cross section orthogonal to the direction in which the compartment 104 extends, the length in the normal direction from the boundary between the outer peripheral wall 101 and the outermost peripheral side compartment 104 or partition wall 105 to the outer side surface of the honeycomb structure. Similarly, the thickness of the inner peripheral wall 106 means: in the same cross section, the length in the normal direction from the boundary between the inner peripheral wall 106 and the innermost peripheral side compartment 104 or partition wall 105 to the inner side surface of the honeycomb structure.

[0074] The thickness of the partition wall 105 is not particularly limited, and is preferably 0.01 to 0.3 mm, more preferably 0.02 to 0.2 mm, and further preferably 0.03 to 0.1 mm. By controlling the thickness of the partition wall 105 within such a range, the strength of the honeycomb structure can be ensured.

[0075] Here, in this specification, the thickness of the partition wall 105 means: in a cross section orthogonal to the direction in which the compartment 104 extends, when the centers of gravity of adjacent compartments 104 are connected by a line segment, the length of the line segment crossing the partition wall 105. The thickness of the partition wall 105 is the average value of the thicknesses of all the partition walls 105.

[0076] The cell density is not particularly limited, and is preferably 30 to 100 cells / cm 2 , more preferably 35 to 70 cells / cm 2 , further preferably 40 to 65 cells / cm 2 . By controlling the cell density within such a range, the strength of the honeycomb structure can be ensured.

[0077] Here, in this specification, the cell density is a value obtained by dividing the number of cells by the area (the total area of the partition walls 105 and the compartments 104 excluding the outer peripheral wall 101) of one end face (the first end face 102 or the second end face 103) of the honeycomb structure.

[0078] The compartment spacing is not particularly limited, preferably 1.0 to 2.0 mm, more preferably 1.2 to 1.8 mm, and further preferably 1.3 to 1.6 mm or more. By controlling the compartment spacing within such a range, the strength of the honeycomb structure can be ensured.

[0079] Here, in this specification, the compartment spacing refers to the value obtained by the following calculation. First, the area of one end face (the first end face 102 or the second end face 103) of the honeycomb structure (the total area of the partition walls 105 and the compartments 104 excluding the outer peripheral wall 101) is divided by the number of compartments to calculate the area of each compartment. Next, the square root of the area of each compartment is calculated and set as the compartment spacing.

[0080] The length in the direction in which the compartment 104 of the honeycomb structure extends and the cross-sectional area orthogonal to the flow path direction can be adjusted according to the required size of the heating unit 100 and are not particularly limited. For example, in the case of a heating unit 100 that is used to ensure a specified function and is compact, in the honeycomb structure, the length in the direction in which the compartment 104 extends can be set to 2 to 20 mm, and the cross-sectional area orthogonal to this direction can be set to 10 cm 2 or more. It should be noted that the upper limit value of the cross-sectional area orthogonal to the direction in which the compartment 104 extends is not particularly limited, for example, it is 300 cm 2 .

[0081] The partition wall 105 constituting the honeycomb structure is made of a material that can generate heat by energization. Specifically, it is made of a material having PTC characteristics. If necessary, the outer peripheral wall 101 and the inner peripheral wall 106 can also be made of a material having PTC characteristics in the same manner as the partition wall 105. By adopting such a configuration, the refrigerant flowing through the refrigerant pipe 20 can be heated by heat transfer from the heat-generating partition wall 105 (and the outer peripheral wall 101 and the inner peripheral wall 106 if necessary). In addition, the material having PTC characteristics has the following characteristics: when the temperature rises and exceeds the Curie point, the resistance value rises sharply, making it difficult for current to flow. Therefore, when the partition wall 105 reaches a high temperature, the current flowing through them is restricted, and thus, excessive heating of the honeycomb structure is suppressed.

[0082] From the viewpoint of obtaining moderate heat generation, the lower limit of the volume resistivity of the material having PTC characteristics at 25°C is preferably 0.5 Ω·cm or more, more preferably 1 Ω·cm or more, and still more preferably 5 Ω·cm or more. From the viewpoint of causing it to generate heat at a low driving voltage, the upper limit of the volume resistivity of the material having PTC characteristics at 25°C is preferably 30 Ω·cm or less, more preferably 18 Ω·cm or less, and still more preferably 16 Ω·cm or less. In this specification, the volume resistivity of the material having PTC characteristics at 25°C is measured in accordance with JIS K6271:2008.

[0083] From the viewpoint of being able to generate heat by energization and having PTC characteristics, the material having PTC characteristics preferably has barium titanate (BaTiO3) as the main component. In addition, this material is more preferably a ceramic composed of a material mainly composed of barium titanate (BaTiO3) - based crystal particles in which a part of Ba is replaced by a rare earth element. It should be noted that in this specification, "main component" means a component that occupies a proportion of more than 50% by mass in the overall composition. The content of BaTiO3 - based crystal particles can be determined by fluorescence X - ray analysis. For other crystal particles, they can also be measured in the same way as this method.

[0084] The composition formula of the BaTiO3 - based crystal particles in which a part of Ba is replaced by a rare earth element can be expressed as (Ba 1-x A x )TiO3. In the composition formula, A represents one or more rare earth elements, and 0.0001 ≤ x ≤ 0.010.

[0085] A may be a rare earth element without particular limitation, and 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. From the viewpoint of suppressing excessive resistance at room temperature, x is preferably 0.001 or more, and more preferably 0.0015 or more. On the other hand, from the viewpoint of suppressing excessive resistance at room temperature due to insufficient sintering, x is preferably 0.009 or less.

[0086] The content of the BaTiO3 - based crystal particles in which a part of Ba is replaced by a rare earth element in the ceramic may be an amount that becomes the main component without particular limitation, and is preferably 90% by mass or more, more preferably 92% by mass or more, and still more preferably 94% by mass or more. It should be noted that the upper limit value of the content of BaTiO3 - based crystal particles is not particularly limited, and is usually 99% by mass, and preferably 98% by mass.

[0087] The content of the BaTiO3 - based crystal particles can be measured by fluorescence X - ray analysis. For other crystal particles, they can also be measured in the same way as this method.

[0088] From the viewpoint of reducing the environmental load, the material having PTC characteristics preferably contains substantially no lead (Pb). Specifically, in the material having PTC characteristics, the Pb content is preferably 0.01% by mass or less, more preferably 0.001% by mass or less, and still more preferably 0% by mass. It should be noted that in the material having PTC characteristics, the Pb content in terms of PbO conversion is preferably less than 0.03% by mass, more preferably less than 0.01% by mass, and still more preferably 0% by mass. The content of lead can be determined by ICP-MS (inductively coupled plasma mass spectrometry).

[0089] The Curie point of the material having PTC characteristics is preferably in the temperature range when the resistance value changes to 2 times or more the resistance value at room temperature (25°C). If the Curie point is within such a temperature range, when the honeycomb structure reaches a high temperature, the current flowing through them is restricted, and thus, overheating of the heating unit 100 can be efficiently suppressed.

[0090] From the viewpoint of efficiently heating the refrigerant, the lower limit of the Curie point of the material having PTC characteristics is preferably 80°C or higher, more preferably 100°C or higher, still more preferably 110°C or higher, and particularly preferably 125°C or higher. In addition, from the viewpoint of the safety of the components of the air conditioning system, the upper limit of the Curie point is preferably 200°C or lower, more preferably 190°C or lower, still more preferably 180°C or lower, and particularly preferably 150°C or lower.

[0091] The Curie point of the material having PTC characteristics can be adjusted by the type and addition amount of the displacement agent. For example, the Curie point of barium titanate (BaTiO3) is about 120°C, and by substituting a part of Ba and Ti with one or more of Sr, Sn, and Zr, the Curie point can be shifted to the low temperature side.

[0092] In this specification, the Curie point is measured by the following method. The specimen is installed in the specimen holder for measurement and assembled in the measurement cell (e.g., MINI-SUBZERO MC-810P manufactured by Espec Corporation), and the change in the resistance of the specimen with respect to the temperature change when heating from 10°C is measured using a DC resistance meter (e.g., multimeter 3478A manufactured by YOKOGAWA HEWLETT PACKARD, LTD). Based on the resistance-temperature graph obtained from the measurement, the temperature at which the resistance value becomes 2 times the resistance value at room temperature (20°C) is set as the Curie point.

[0093] The honeycomb structure may be provided with a pair of electrodes 107 and 108 as shown in Figure 2A The positions of the pair of electrodes 107 and 108 may be as shown in Figure 2AThe above is disposed on the first end face 102 and the second end face 103. In addition, the positions of the pair of electrodes 107 and 108 can also be set on the outer peripheral wall 101 parallel to the extending direction of the compartment 104.

[0094] By applying a voltage between the pair of electrodes 107 and 108, the honeycomb structure can be heated by Joule heat.

[0095] There is no particular limitation on the pair of electrodes 107 and 108. For example, a metal or alloy containing at least one selected from Cu, Ag, Al, Ni, and Si can be used. In addition, an ohmic electrode capable of making ohmic contact with the outer peripheral wall 101, the partition wall 105, etc. having PTC characteristics can also be used. As the ohmic electrode, for example, an ohmic electrode containing at least one selected from Al, Au, Ag, and In as the base metal and at least one selected from Ni, Si, Zn, Ge, Sn, Se, and Te for n-type semiconductors as the dopant can be used. In addition, the pair of electrodes 107 and 108 can be a single-layer structure or a laminated structure of two or more layers. When the pair of electrodes 107 and 108 has a laminated structure of two or more layers, the materials of each layer can be of the same type or different types.

[0096] The thickness of the pair of electrodes 107 and 108 can be appropriately set according to the formation method of the pair of electrodes 107 and 108. Examples of the formation method of the pair of electrodes 107 and 108 include metal deposition methods such as sputtering, evaporation plating, electrolytic deposition, and chemical deposition. In addition, the pair of electrodes 107 and 108 can also be formed by a method of sintering after applying electrode paste or by cladding. In addition, the pair of electrodes 107 and 108 can be made by bonding a metal plate or an alloy plate.

[0097] Regarding the thickness of the pair of electrodes 107 and 108, for example, in the sintering of electrode paste, the thickness is preferably about 5 to 30 μm, in dry plating such as sputtering and evaporation plating, the thickness is preferably about 100 to 1000 nm, in cladding, the thickness is preferably about 10 to 100 μm, and in wet plating such as electrolytic deposition and chemical deposition, the thickness is preferably about 5 to 30 μm. In addition, in the bonding of a metal plate or an alloy plate, it is preferable to set their thickness to about 5 to 100 μm.

[0098] The honeycomb structure can further include terminals connected to the pair of electrodes 107 and 108. By providing the terminals, it becomes easy to connect to an external power source.

[0099] The material of the terminal is not particularly limited and may be, for example, a metal. As the metal, a simple metal, an alloy, etc. can be used. From the viewpoints of corrosion resistance, resistivity, and linear expansion rate, for example, it is preferably an alloy containing at least one selected from the group consisting of Cr, Fe, Co, Ni, Cu, Al, and Ti, and more preferably stainless steel, Fe-Ni alloy, and phosphor bronze.

[0100] The thickness of the terminal is not particularly limited and is, for example, 0.01 to 10 mm, typically 0.05 to 5 mm.

[0101] Regarding the connection method between the terminal and the pair of electrodes 107 and 108, electrical connection is sufficient and not particularly limited. For example, it can be connected by diffusion bonding, a mechanical pressing mechanism, welding, etc.

[0102] The manufacturing method of the honeycomb structure constituting the heating unit 100 is not particularly limited and can be carried out according to a known method. Hereinafter, a typical manufacturing example of the honeycomb structure will be described.

[0103] The manufacturing method of the honeycomb structure includes a forming process and a firing process.

[0104] In the forming process, a blank containing a ceramic raw material including powders such as BaCO3 powder, TiO2 powder, and rare earth nitrates or hydroxides is formed to produce a honeycomb green body with a relative density of 60% or more.

[0105] Each powder can be dry-mixed according to a desired composition to obtain a ceramic raw material.

[0106] A blank can be obtained by adding a dispersion medium, a binder, a plasticizer, and a dispersant to the ceramic raw material and kneading. Additives such as a displacement agent, a metal oxide, a property improver, and a conductive powder can be contained in the blank as needed.

[0107] The blending amount of the components other than the ceramic raw material is not particularly limited as long as the relative density of the honeycomb green body reaches 60% or more.

[0108] Here, the "relative density of the honeycomb green body" in this specification means the ratio of the density of the honeycomb green body to the true density of the entire ceramic raw material. Specifically, it can be obtained by the following formula.

[0109] Relative density of honeycomb green body (%) = density of honeycomb green body (g / cm 3 ) / true density of entire ceramic raw material (g / cm 3 ) × 100

[0110] The density of the honeycomb formed body can be measured by the Archimedes method using pure water as the medium. In addition, the true density of the entire ceramic raw material can be obtained by dividing the total mass value (g) of each raw material by the total actual volume value (cm 3 ) of each raw material.

[0111] As the dispersion medium, examples include: water, or a mixed solvent of water and an organic solvent such as alcohol, etc., and water can be particularly preferably used.

[0112] As the binder, examples include: organic binders such as methylcellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, etc. It is particularly preferred to use a combination of methylcellulose and hydroxypropoxyl cellulose. The binder can be used alone or in combination of two or more, however, it is preferably free of alkali metal elements.

[0113] As the plasticizer, examples include: polyoxyethylene alkyl ether, polycarboxylic acid-based polymers, alkyl phosphates, etc.

[0114] As the dispersant, surfactants such as polyoxyethylene alkyl ether, ethylene glycol, dextrin, fatty acid soap, polyhydric alcohol, etc. can be used. The dispersant can be used alone or in combination of two or more.

[0115] The honeycomb formed body can be produced by extruding the blank. During the extrusion molding, a die having a desired overall shape, compartment shape, thickness of each part, compartment density, etc. can be used.

[0116] 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 such a range, the honeycomb formed body can be densified and the resistance at room temperature can be reduced. It should be noted that the upper limit value of the relative density of the honeycomb formed body is not particularly limited, usually 80%, preferably 75%.

[0117] The honeycomb formed body can be dried before the firing process. As the drying method, there is no particular limitation, for example, conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying, etc. can be used. Among them, in terms of being able to quickly and uniformly dry the entire formed body, a drying method that combines hot air drying and microwave drying or dielectric drying is preferred.

[0118] The firing process includes: holding at 1150 - 1250 °C and then raising the temperature to the maximum temperature of 1360 - 1430 °C at a heating rate of 20 - 600 °C / hour and holding for 0.5 - 10 hours.

[0119] By holding the honeycomb formed body at a maximum temperature of 1360 to 1430 °C for 0.5 to 10 hours, a honeycomb structure mainly composed of BaTiO3-based crystal particles in which a part of Ba is replaced by a rare earth element can be obtained.

[0120] In addition, by holding at 1150 to 1250 °C, the Ba2TiO4 crystal particles generated during the firing process are easily removed, and thus the honeycomb structure can be densified.

[0121] Furthermore, by setting the heating rate from 1150 to 1250 °C to the maximum temperature of 1360 to 1430 °C to 20 to 600 °C / hour, 1.0 to 10.0 mass% of Ba6Ti 17 O 40 crystal particles can be formed in the honeycomb structure.

[0122] The holding time at 1150 to 1250 °C is not particularly limited, and is preferably 0.5 to 10 hours. By setting the holding time like this, the Ba2TiO4 crystal particles generated during the firing process are easily and stably removed.

[0123] The firing step preferably includes holding at 900 to 950 °C for 0.5 to 5 hours during heating. By holding at 900 to 950 °C for 0.5 to 5 hours, BaCO3 decomposes efficiently, and a honeycomb structure having a predetermined composition can be easily obtained.

[0124] It should be noted that before the firing step, a degreasing step for removing the binder can be performed. The atmosphere of the degreasing step is preferably an air atmosphere in order to completely decompose the organic components.

[0125] In addition, from the viewpoints of controlling electrical characteristics and manufacturing cost, the atmosphere of the firing step is also preferably an air atmosphere.

[0126] The firing furnace used for the firing step or the degreasing step is not particularly limited, and an electric furnace, a gas furnace, etc. can be used.

[0127] A pair of electrodes 107 and 108 are formed on the honeycomb structure obtained in this way. The pair of electrodes 107 and 108 can be formed by a metal deposition method such as sputtering, evaporation, electrolytic deposition, or chemical deposition. In addition, the pair of electrodes 107 and 108 can also be formed by sintering after applying an electrode paste. Furthermore, the pair of electrodes 107 and 108 can also be formed by cladding. The pair of electrodes 107 and 108 can be composed of a single layer or a plurality of electrode layers having different compositions. Hereinafter, representative formation methods of the pair of electrodes 107 and 108 will be described.

[0128] First, an electrode paste containing an electrode material, an organic binder, and a dispersion medium is prepared and coated on the first end face 102 or the second end face 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 (Japanese: テキサノール), 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. The excess paste on the periphery of the honeycomb structure is removed by blowing and wiping. Thereafter, by drying the paste, a pair of electrodes 107, 108 can be formed on the first end face 102 or the second end face 103 of the honeycomb structure. Drying can be performed in a state where the heater member is heated to a temperature of, for example, about 120 to 600°C. The series of processes of coating, paste removal, and drying can be carried out only once, or can be repeated multiple times to form a pair of electrodes 107, 108 with a desired thickness.

[0129] Next, when setting the terminals, the terminals are arranged at specified positions on the pair of electrodes 107, 108, and the pair of electrodes 107, 108 and the terminals are connected. As the connection method between the pair of electrodes 107, 108 and the terminals, the above-described method can be used.

[0130] (3. Control unit 110)

[0131] 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 on-off valves 80a to 80e of the heat pump cycle 10, and by opening and closing the on-off valves 80a to 80e, the flow path of the refrigerant can be controlled. In addition, the control unit 110 is electrically connected to the expansion valves 70a, 70b of the heat pump cycle 10, and by adjusting the opening degrees of the expansion valves 70a, 70b, the degree of decompression of the refrigerant can be controlled. Further, the control unit 110 is connected to a power source for applying a voltage to the pair of electrodes 107, 108 of the heating unit 100, and by controlling the power source, the heating state of the honeycomb structure can be adjusted. It should be noted that the power source is not particularly limited, and a storage battery or the like can be used.

[0132] In addition to being electrically connected to the heat pump cycle 10 and the heating unit 100, the control unit 110 is also electrically connected to the ventilator 130, the air mixing door 140, etc., and can control them.

[0133] The control unit 110 is not particularly limited and is usually an ECU (Engine (electronic) Control Unit). The ECU includes: a CPU that performs various arithmetic processes, a ROM that stores programs or data required for its control, a RAM that temporarily stores arithmetic results in the CPU, and input / output ports for inputting or outputting signals to and from the outside.

[0134] (4. Blower 130)

[0135] The blower 130 is provided to allow air to flow through the air conditioning passage 120. The blower 130 is not particularly limited, and a known blower can be used.

[0136] The position of the blower 130 is not particularly limited. For example, it can be provided on the upstream side of the condenser 40 and the evaporator 50. However, the blower 130 can also be provided on the downstream side of the condenser 40 and the evaporator 50.

[0137] (5. Air mix door 140)

[0138] The air mix door 140 is configured to rotate between a heating position that opens a heating path toward the condenser 40 and a cooling position that opens a cooling path bypassing the condenser 40 in the air conditioning passage 120. In addition, with respect to the air mix door 140, by rotating between the heating position and the cooling position, the ratio between the air passing through the condenser 40 and the air bypassing the condenser 40 can be adjusted, thereby adjusting the temperature of the air flowing into the vehicle interior.

[0139] 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 modes of the heat pump cycle 10 can be selected based on the driver's switch operation, temperature changes based on various monitoring units, and the like.

[0140] (A) Heating operation mode

[0141] Regarding the heating operation mode, as Figure 1A shown, the stop valves 80a to 80c are opened, and the stop valves 80d and 80e are closed, thereby forming a flow path in which the refrigerant flows sequentially through the compressor 30, the condenser 40, the expansion valve 70a, and the outdoor heat exchanger 60. It should be noted that Figure 1A in, the flow path of the refrigerant in this heating operation mode is indicated by a thick line.

[0142] This heating operation mode includes: compressing the refrigerant using the compressor 30, and introducing the refrigerant ejected from the compressor 30 into the condenser 40 to heat the air. That is, the refrigerant compressed by the compressor 30 enters the condenser 40 as a high-temperature and high-pressure refrigerant, and exchanges heat with the air flowing in the air conditioning passage 120 to release heat (heat the air). The refrigerant leaving the condenser 40 is decompressed and expanded by the expansion valve 70a, becomes a low-temperature and low-pressure refrigerant, exchanges heat with the external atmosphere in the outdoor heat exchanger 60 to absorb heat, and returns to the compressor 30.

[0143] When implementing this heating operation mode, the air flowing in the air conditioning passage 120 is heated by the condenser 40, and the heated air flows into the vehicle compartment. The temperature of the air flowing into the vehicle compartment can be adjusted by controlling the opening degree of the air mixing door 140.

[0144] In addition, the control unit 110 includes: at the start of this heating operation mode, controlling in such a way that a voltage is applied to the honeycomb structure constituting the heating unit 100 to heat the refrigerant. By controlling in this way, even when the temperature of the refrigerant in the heat pump cycle 10 is low in cold weather, the refrigerant can be heated quickly, so that the initial heating performance can be improved.

[0145] (B) First cooling operation mode

[0146] Regarding the first cooling operation mode, as Figure 1B shown, open the stop valves 80a, 80d, 80e, and close the stop valves 80b and 80c, thereby forming a flow path in which the refrigerant flows sequentially through the compressor 30, the outdoor heat exchanger 60, the expansion valve 70b, and the evaporator 50. It should be noted that Figure 1B in, the flow path of the refrigerant flow in this cooling operation mode is shown by a thick line.

[0147] This cooling operation mode includes: introducing the refrigerant decompressed and expanded by the expansion valve 70b into the evaporator 50 to cool the air. That is, the refrigerant compressed by the compressor 30 to become high-temperature and high-pressure exchanges heat with the external atmosphere in the outdoor heat exchanger 60 to release heat, and is thus cooled. The refrigerant leaving the outdoor heat exchanger 60 is decompressed and expanded by the expansion valve 70b, becomes a low-temperature and low-pressure refrigerant, enters the evaporator 50, and exchanges heat with the air flowing in the air conditioning passage 120 to absorb heat (cool the air). The refrigerant leaving the evaporator 50 returns to the compressor 30.

[0148] When implementing this cooling operation mode, the air flowing in the air conditioning passage 120 is cooled by the evaporator 50, and the cooled air flows into the vehicle compartment. This cooling operation mode is particularly useful for the situation where it is desired to quickly cool the interior of the vehicle compartment (strong cooling operation mode).

[0149] (C) Second cooling operation mode

[0150] Regarding the second cooling operation mode, as Figure 1C shown, open the stop valves 80a, 80c, 80e, and close the stop valves 80b, 80d, thereby forming a refrigerant flow path in which the refrigerant flows through the compressor 30, condenser 40, expansion valve 70a, outdoor heat exchanger 60, expansion valve 70b, and evaporator 50 in sequence. It should be noted that Figure 1C in, the flow path of the refrigerant in this cooling operation mode is indicated by a thick line.

[0151] In the refrigerant flow path in this cooling operation mode, a condenser 40 and an expansion valve 70a are also arranged on the downstream side of the compressor 30. Moreover, in this cooling operation mode, by controlling the opening degree of the air mixing door 140, the cooling of the air by the evaporator 50 and the heating of the air by the condenser 40 can be adjusted. Therefore, the temperature of the air can be controlled to the optimal temperature.

Claims

1. An air conditioning system having a heat pump cycle, the heat pump cycle including a refrigerant pipe through which a refrigerant can circulate and a compressor capable of compressing the refrigerant. The air conditioning system is characterized in that based on the flow direction of the refrigerant, a heating part capable of heating the refrigerant is provided in the refrigerant pipe on the upstream side, downstream side, or both sides of the compressor. The heating part includes a honeycomb structure having an outer peripheral wall and partition walls, the partition walls being disposed inside the outer peripheral wall and partitioning to form a plurality of compartments extending from a first end face to a second end face, and at least the partition walls are made of a material having PTC characteristics.

2. The air conditioning system according to claim 1, characterized in that the air conditioning system further includes a control part for controlling the heat pump cycle and the heating part, the control part includes: at the start of the heating operation mode of the heat pump cycle, controlling to apply a voltage to the honeycomb structure to heat the refrigerant.

3. The air conditioning system according to claim 2, characterized in that the heat pump cycle further has a condenser that performs heat exchange between the air flowing in the air conditioning passage and the refrigerant. The heating operation mode includes: compressing the refrigerant by the compressor and introducing the refrigerant ejected from the compressor into the condenser to heat the air.

4. The air conditioning system according to claim 3, characterized in that the heat pump cycle further includes: an evaporator that performs heat exchange between the air flowing in the air conditioning passage and the refrigerant; and an outdoor heat exchanger that performs heat exchange between the outside air and the refrigerant.

5. The air conditioning system according to claim 4, characterized in that the heating part is provided in the refrigerant pipe between the compressor and the condenser, between the compressor and the evaporator or the outdoor heat exchanger, or both.

6. The air conditioning system according to any one of claims 1 to 5, characterized in that the material having PTC characteristics has barium titanate as a main component.

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

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