Heater element, heater unit and heater system for heating vehicle interior, and heater element for purifying vehicle interior

Abstract

Provided is a heater element 100 comprising: a honeycomb structure 10 having an outer peripheral wall 11 and a partition wall 12 that is disposed inside the outer peripheral wall 11 and that defines and forms a plurality of cells 14 forming a flow passage from a first end surface 13a to a second end surface 13b, the outer peripheral wall 11 and the partition wall 12 being configured from a material having PTC characteristics; and a pair of electrode layers 20 disposed on the surface of the outer peripheral wall 11. The honeycomb structure 10 has a shape having a long axis X2 and a short axis X3 in a cross-section orthogonal to a central axis X1. The pair of electrode layers 20 are formed in band shapes extending parallel to the central axis X1. In the cross-section orthogonal to the central axis X1, the pair of electrode layers 20 are disposed on the surface of the outer peripheral wall 11 so as to face each other across the long axis X2, which passes through the center of gravity of the honeycomb structure 10. The heater element 100 furthermore comprises plate-form external connection members 30 that are disposed on the end-section sides of the electrode layers 20 and that are in planar contact with the electrode layers 20..

Description

[Technical field]

[0001] The present invention relates to a heater element, a heater unit and a heater system for heating a vehicle interior, and a heater element for purifying a vehicle interior. [Background technology]

[0002] In recent years, heater systems have been adopted for heating the passenger compartment of electric vehicles that use a vapor compression heat pump as the main heater, and also use a heater that utilizes Joule heat as an auxiliary heater when rapid heating is required at the start of the vehicle or when the outside temperature is very low. As a heater that utilizes Joule heat and is used in this heater system, Patent Document 1 proposes a heater element using a honeycomb structure that is compact and can increase the heat transfer area per volume. This heater element includes a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall that partition a plurality of cells that form a flow path from a first end face to a second end face, and a pair of electrode layers disposed on the first end face and the second end face, and can generate heat by applying a voltage between the pair of electrodes to pass electricity in the direction of the flow path. However, the heater element described in Patent Document 1 has electrodes facing the gas flow path, which may cause corrosion of the electrodes, and therefore the reliability is not sufficient.

[0003] Therefore, Patent Document 2 proposes a heater element in which a pair of electrode layers are disposed on the surface of the outer wall of a honeycomb structure. In this heater element, the electrode layers do not face the gas flow path, so that corrosion of the electrode layers can be suppressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 036067 [Patent Document 2] JP 2020-59443 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the heater element described in Patent Document 2 connects the electrode layer to the outside (e.g., a battery) by an electric wire. In this heater element, the contact area between the electric wire and the electrode layer is small, so the amount of power supplied from the outside is limited, and there is a problem that the heat generation performance is insufficient. In addition, the honeycomb structure used in the heater element of Patent Document 2 is made of a material that does not have PTC properties, and the current is controlled by the increase in electrical resistance that accompanies a temperature rise in the PTC material layer in contact with the outer wall of the honeycomb structure. Therefore, the sensitivity of temperature control is also lower than when the honeycomb structure is made of a material that has PTC properties. The present invention has been made to solve the above problems, and aims to provide a heater element for heating a vehicle interior that can increase the amount of power supplied from the outside and improve heat generation performance, as well as a heater unit and heater system for heating a vehicle interior that use the heater element. Another aim of the present invention is to provide a heater element that can also be used for purifying the vehicle interior. [Means for solving the problem]

[0006] The above problems are solved by the present invention, which is specified as follows:

[0007] That is, the present invention provides a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells that form a flow path from a first end surface to a second end surface, the outer peripheral wall and the partition walls being made of a material having a PTC characteristic; A pair of electrode layers disposed on a surface of the outer peripheral wall; A heater element for heating a vehicle interior, comprising: The honeycomb structure has a shape having a long axis and a short axis in a cross section perpendicular to a central axis, the pair of electrode layers are formed in a band shape extending parallel to the central axis, and are arranged on the surface of the outer peripheral wall so as to face each other across a long axis passing through the center of gravity of the honeycomb structure in a cross section perpendicular to the central axis, The heater element has a Parallel to the central axis Further provided is a plate-shaped external connection member disposed on the end side and in flat contact with each electrode layer. picture, an end side of each of the electrode layers parallel to the central axis is a region from the end of each of the electrode layers to 30% of the entire length of each of the electrode layers in a long axis direction passing through the center of gravity of the honeycomb structure, and the external connection members extend in the same direction from the end side of each of the electrode layers parallel to the central axis toward the outside, and the entire external connection member has approximately the same width as the width of the end of each of the electrode layers. It is a heater element.

[0008] The present invention also provides a heater unit for heating a vehicle interior, comprising two or more of the heater elements, In the heater unit, the heater elements are stacked and arranged so that the surfaces of the outer peripheral walls of the honeycomb structures, which include the long sides of the first end face and the second end face, face each other.

[0009] The present invention also relates to the heater unit, An inlet pipe communicating an outside air introduction portion or a vehicle interior with an inlet of the heater unit; a battery for applying a voltage to the heater unit; and An outlet pipe that connects the outlet of the heater unit to the vehicle compartment This is a heater system for heating a vehicle interior.

[0010] Furthermore, the present invention provides a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells that form a flow path from a first end surface to a second end surface, the outer peripheral wall and the partition walls being made of a material having a PTC characteristic; A pair of electrode layers disposed on a surface of the outer peripheral wall; a functional material-containing layer provided on a surface of the partition wall; A heater element for purifying a vehicle interior, comprising: The honeycomb structure has a shape having a long axis and a short axis in a cross section perpendicular to a central axis, the pair of electrode layers are formed in a band shape extending parallel to the central axis, and are arranged on the surface of the outer peripheral wall so as to face each other across a long axis passing through the center of gravity of the honeycomb structure in a cross section perpendicular to the central axis, The heater element has a Parallel to the central axis Further provided is a plate-shaped external connection member disposed on the end side and in flat contact with each electrode layer. picture, an end side of each of the electrode layers parallel to the central axis is a region from the end of each of the electrode layers to 30% of the entire length of each of the electrode layers in a long axis direction passing through the center of gravity of the honeycomb structure, and the external connection members extend in the same direction from the end side of each of the electrode layers parallel to the central axis toward the outside, and the entire external connection member has approximately the same width as the width of the end of each of the electrode layers. It is a heater element. Effect of the Invention

[0011] According to the present invention, it is possible to provide a heater element for heating a vehicle interior that can increase the amount of power supplied from outside and improve heat generation performance, as well as a heater unit and a heater system for heating a vehicle interior that use the heater element. Also, according to the present invention, it is possible to provide a heater element that can be used for purifying the vehicle interior. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic perspective view of a heater element according to an embodiment of the present invention. [Diagram 2] 2 is a schematic cross-sectional view of the heater element of FIG. 1 perpendicular to the central axis of the honeycomb structure. [Diagram 3] FIG. 4 is a schematic cross-sectional view of another heater element according to an embodiment of the present invention, perpendicular to the central axis of the honeycomb structure. [Figure 4] FIG. 4 is a schematic cross-sectional view of another heater element according to an embodiment of the present invention, perpendicular to the central axis of the honeycomb structure. [Diagram 5] FIG. 4 is a schematic cross-sectional view of another heater element according to an embodiment of the present invention, perpendicular to the central axis of the honeycomb structure. [Figure 6] FIG. 4 is a schematic cross-sectional view of another heater element according to an embodiment of the present invention, perpendicular to the central axis of the honeycomb structure. [Figure 7]FIG. 3 is a partially enlarged view of a honeycomb structure in the heater element of FIG. 2. [Figure 8] FIG. 2 is a schematic cross-sectional view perpendicular to the central axis of a honeycomb joined body having five honeycomb segments. [Figure 9] FIG. 4 is a schematic partially enlarged cross-sectional view of another heater element according to an embodiment of the present invention, perpendicular to the central axis of the honeycomb structure. [Figure 10] FIG. 2 is a schematic front view of the heater unit according to the embodiment of the present invention as viewed from a first end face side of the heater element. [Figure 11] FIG. 2 is a schematic front view of another heater unit according to an embodiment of the present invention as viewed from a first end face side of a heater element. [Figure 12] FIG. 2 is a schematic front view of another heater unit according to an embodiment of the present invention as viewed from a first end face side of a heater element. [Figure 13] FIG. 1 is a schematic diagram showing a configuration example of a heater system according to an embodiment of the present invention. [Figure 14] FIG. 2 is a schematic cross-sectional view of the heater element produced in Example 1, perpendicular to the central axis of the honeycomb joined body. [Figure 15] FIG. 2 is a schematic diagram of an evaluation box used in the examples. [Figure 16] 1 shows the current density distribution results for the heater elements produced in Examples 1 and 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the 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 to the following embodiments, which are made based on the ordinary knowledge of a person skilled in the art, fall within the scope of the present invention, without departing from the spirit of the present invention.

[0014] (1. Heater element) The heater element according to the embodiment of the present invention can be suitably used as a heater element for heating the passenger compartment of a vehicle. Examples of the vehicle include, but are not limited to, automobiles and trains. Examples of the automobile include, but are not limited to, gasoline vehicles, diesel 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 heater element according to the embodiment of the present invention can be suitably used in vehicles that do not have an internal combustion engine, such as electric vehicles and trains.

[0015] Fig. 1 is a schematic perspective view of a heater element according to an embodiment of the present invention, Fig. 2 is a schematic cross-sectional view of the heater element of Fig. 1 perpendicular to the central axis of a honeycomb structure. The heater element 100 according to the embodiment of the present invention includes a honeycomb structure 10 having an outer peripheral wall 11, partition walls 12 disposed inside the outer peripheral wall 11 and partitioning a plurality of cells 14 that form a flow path from a first end face 13a to a second end face 13b, and a pair of electrode layers 20 disposed on the surface of the outer peripheral wall 11. The honeycomb structure 10 has a shape having a long axis X2 and a short axis X3 in a cross section perpendicular to the central axis X1. The pair of electrode layers 20 are formed in a band shape extending parallel to the central axis X1, and are disposed on the surface of the outer peripheral wall 11 so as to face each other across the long axis X2 passing through the center of gravity of the honeycomb structure 10 in the cross section perpendicular to the central axis X1. The heater element 100 further includes a plate-shaped external connection member 30 disposed on the end side of each electrode layer 20 and in contact with each electrode layer 20 in a flat surface. By arranging the electrode layer 20 and the external connection member 30 in this manner, the electrode layer 20 and the external connection member 30 come into surface contact with each other, making it easier to increase the amount of power supplied from the outside, thereby improving heat generation performance. Each of the components of the heater element 100 will now be described in detail.

[0016] (1-1. Honeycomb structure 10) The honeycomb structure 10 is not particularly limited in shape as long as the cross section perpendicular to the central axis X1 has a long axis X2 and a short axis X3. The shape of the honeycomb structure 10 may be, for example, a rectangular shape, an oval shape (egg shape, ellipse shape, oval shape, rounded rectangle, etc.), or a polygonal shape (hexagonal shape, octagonal shape, etc., in which at least two opposing sides are longer than the other sides) in the cross section (outer shape) perpendicular to the central axis X1. Among these, the cross section is preferably rectangular. The end faces (first end face 13a and second end face 13b) have the same shape as the cross section. When the cross section is rectangular, the cross section has a short side 15 and a long side 16. A pair of electrode layers 20 are disposed on both sides of the outer peripheral wall 11 including the long side 16. The ratio of the length of the short side 15 to the length of the long side 16 is not particularly limited, but is preferably 1:2 to 1:15, more preferably 1:2 to 1:10, and even more preferably 1:3 to 1:8. By controlling the ratio within such a range, it becomes easy to match the size of the heater element used in an existing heater unit. The length of the long side 16 can be, for example, 30 mm to 250 mm. The length of the short side 15 can be, for example, 5 mm to 200 mm. In particular, by making the length of the short side 15 10 mm or less and reducing the distance between the pair of electrode layers 20, heating can be achieved even with an applied voltage as low as about 10 V.

[0017] The shape of the cells 14 in a cross section perpendicular to the central axis X1 is not particularly limited, but is preferably a quadrangle (rectangle, square), a hexagon, an octagon, or a combination of two or more of these. Among these, a quadrangle and a hexagon are preferred, and a hexagon is more preferred. By making the cell 14 into such a shape, the pressure loss during gas passage can be reduced. 1 and 2 show an example of a honeycomb structure 10 in which the cross section perpendicular to the central axis X1 is rectangular and the cells 14 are square in shape.

[0018] Here, examples of heater elements having honeycomb structures 10 having other shapes are shown in Figs. FIG. 3 shows an example of a heater element 200 including a honeycomb structure 10 having a cross section perpendicular to the central axis X1 that is a rounded rectangle (racetrack shape) and the cells 14 have a square shape. FIG. 4 shows an example of a heater element 300 including a honeycomb structure 10 having an elliptical cross section and cells 14 each having a rectangular shape in a cross section perpendicular to the central axis X1. FIG. 5 shows an example of a heater element 400 including a honeycomb structure 10 having a cross section perpendicular to the central axis X1 that is a rounded rectangle (racetrack shape) and the shape of the cells 14 is hexagonal. FIG. 6 shows an example of a heater element 500 having a honeycomb structure 10 in which the cross section perpendicular to the central axis X1 is a hexagon in which the two opposing sides on which the electrode layers 20 are provided are longer than the other sides, and the shape of the cells 14 is rectangular. In any of the above heater elements 200, 300, 400, and 500, a pair of electrode layers 20 are arranged on the surface of the outer wall 11 so as to face each other across the long axis X2 passing through the center of gravity of the honeycomb structure 10 in a cross section perpendicular to the central axis X1, and a plate-shaped external connection member 30 is arranged on the end side of each electrode layer 20 so as to be in planar contact with each electrode layer 20. In the following, the heater element 100 will be mainly described, but the same applies to the heater elements 200, 300, 400, and 500.

[0019] It is preferable that the honeycomb structure 10 does not have partition walls 12 parallel to the long axis X2 in a cross section perpendicular to the central axis X1. With such a configuration, the cells 14 can be uniformly heated during heating use, and deformation and cracks of the cells 14 can be suppressed. Here, a partial enlarged view of the honeycomb structure 10 in the heater element 100 of FIG. 2 is shown in FIG. 7. As shown in FIG. 7, the partition walls 12 have angles α and β with respect to the long axis X2. These angles α and β are preferably 30 to 60°. By controlling the angles α and β of the partition walls 12 with respect to the long axis X2 within the range, it is possible to stably obtain the effect of suppressing deformation and cracks of the cells 14 during heating use.

[0020] The honeycomb structure 10 may be a honeycomb bonded body having a plurality of honeycomb segments and a bonding layer bonding 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 14, which is important for ensuring the gas flow rate, while suppressing the occurrence of cracks. Here, as an example, a schematic cross-sectional view perpendicular to the central axis X1 of a honeycomb joined body having five honeycomb segments is shown in FIG. 8, the honeycomb joined body 17 has five honeycomb segments 18 and a joining layer 19 joining the honeycomb segments 18. Each honeycomb segment 18 has an outer peripheral wall 11 and partition walls 12 disposed inside the outer peripheral wall 11 and defining a plurality of cells 14 that form flow paths from a first end face 13a to a second end face 13b.

[0021] The bonding layer 19 can be formed using a bonding material. The bonding material is not particularly limited, and a ceramic material having a solvent such as water added thereto to form a paste can be used. The bonding material may contain ceramics having PTC properties, or may contain the same ceramics as the outer peripheral wall 11 and the partition walls 12. In addition to the role of bonding the honeycomb segments 18 together, the bonding material can also be used as an outer peripheral coating material after bonding the honeycomb segments 18.

[0022] The area of ​​each end face of the honeycomb structure 10 is not particularly limited, but may be, for example, 20 to 500 cm 2 The length of the honeycomb structure 10 (the length of the passage of each cell 14) is not particularly limited, but may be, for example, 3 to 40 mm.

[0023] (1-1-1. Material of honeycomb structure 10) The outer peripheral wall 11 and the partition walls 12 of the honeycomb structure 10 are made of a material that can generate heat when electricity is applied thereto. Therefore, a gas such as outside air or air inside a vehicle can be heated by heat transfer from the outer peripheral wall 11 and the partition walls 12 that generate heat, from when the gas flows in from the first end face 13a, passes through the multiple cells 14, and flows out from the second end face 13b.

[0024] In addition, the outer peripheral wall 11 and the partition wall 12 are made of a material having a PTC (Positive Temperature Coefficient) characteristic. In other words, the outer peripheral wall 11 and the partition wall 12 have a characteristic that when the temperature rises and exceeds the Curie point, the resistance value rises rapidly and it becomes difficult for electricity to flow. Since the outer peripheral wall 11 and the partition wall 12 have the PTC characteristic, when the heater element 100 becomes hot, the current flowing therethrough is limited, so that excessive heat generation of the heater element 100 is suppressed.

[0025] From the viewpoint of being electrically heatable and having PTC characteristics, the outer peripheral wall 11 and the partition wall 12 are preferably ceramics composed of a material mainly composed of barium titanate (BaTiO3)-based crystal particles in which part of Ba is replaced with a rare earth element. In this specification, the term "main component" means a component whose proportion of the total components exceeds 50 mass%. The content of BaTiO3-based crystal particles can be determined, for example, by fluorescent X-ray analysis or EDAX (energy dispersive X-ray) analysis. Other crystal particles can also be measured in the same manner.

[0026] 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 Sc, Y, La, Ce, Pr, Nd, Eu, Gd, Dy, Ho, Er and Yb, and more preferably La. x is preferably 0.001 or more, more preferably 0.0015 or more, and even more preferably 0.002 or more from the viewpoint of suppressing the electrical resistance at room temperature from becoming too high. On the other hand, x is preferably 0.010 or less, more preferably 0.009 or less, and even more preferably 0.008 or less from the viewpoint of suppressing the electrical resistance at room temperature from becoming too high due to insufficient sintering.

[0027] The BaTiO3-based crystal particles in which a part of Ba is replaced by a rare earth element preferably have a (Ba+rare earth element) / Ti ratio of 1.005 to 1.050. By controlling the (Ba+rare earth element) / Ti ratio within such a range, the electrical resistance at room temperature can be stably reduced. The element ratio of Ba, rare earth element, and Ti can be determined, for example, by X-ray fluorescence analysis, ICP-MS (inductively coupled plasma mass spectrometry), etc.

[0028] The BaTiO3-based crystal particles in which a portion of Ba is substituted with a rare earth element preferably have an average crystal grain size of 5 to 200 μm, more preferably 5 to 180 μm, and even more preferably 5 to 160 μm. By controlling the average crystal grain size within such a range, the electrical resistance at room temperature can be stably reduced. The average crystal grain size of the BaTiO3-based crystal grains can be measured as follows. A square specimen of 5 mm x 5 mm x 5 mm is cut out from the ceramic and embedded in resin. The embedded specimen is mechanically polished to a mirror finish and observed with an SEM. The SEM observation is performed, for example, using a Hitachi High-Technologies Corporation model S-3400N, with an acceleration voltage of 15 kV and a magnification of 3000. In the SEM observation image (30 μm long x 45 μm wide), four straight lines of 0.3 μm in width are drawn across the entire vertical direction of the field of view at 10 μm intervals, and the number of BaTiO3-based crystal grains through which any part of the straight lines pass is counted. The length of the straight lines is divided by the number of BaTiO3-based crystal grains, and the average of the lengths of the lines divided by the number of BaTiO3-based crystal grains is taken as the average crystal grain size for four or more SEM observation images.

[0029] The content of BaTiO3-based crystal particles in the ceramics, in which a part of Ba is replaced by a rare earth element, is not particularly limited as long as it is the amount that serves as the main component, but is preferably 90 mass% or more, more preferably 92 mass% or more, and 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 the BaTiO3 crystal particles can be measured by, for example, fluorescent X-ray analysis or EDAX (energy dispersive X-ray) analysis. Other crystal particles can also be measured in the same manner.

[0030] The ceramics used for the outer peripheral wall 11 and the partition wall 12 are Ba6Ti 17 O 40 It is preferable that the ceramic contains crystal grains. 17 O 40 The presence of crystal grains can reduce electrical resistance at room temperature. 17 O 40 It is believed that the crystal particles become liquid during the firing process, promoting rearrangement, grain growth, and densification of BaTiO3-based crystal particles, thereby decreasing the electrical resistance at room temperature.

[0031] Ba6Ti in ceramics 17 O 40 The content of the crystal particles is 1.0 to 10.0% by mass, preferably 1.2 to 8.0% by mass, and more preferably 1.5 to 6.0% by mass. 17 O 40 By making the crystal grains 1.0 mass% or more, Ba6Ti 17 O 40 The effect of the presence of crystal particles (i.e., the effect of reducing electrical resistance at room temperature) can be obtained. 17 O 40 By keeping the crystal grains at 10.0 mass % or less, the PTC characteristics can be ensured.

[0032] The ceramics used for the outer peripheral wall 11 and the partition walls 12 may further contain BaCO3 crystal particles. The BaCO3 crystal particles are crystal particles derived from BaCO3 powder, which is a raw material for the ceramics. BaCO3 crystal particles do not have much effect on the electrical resistance of ceramics at room temperature, so they may not be included in ceramics. However, if the content of BaCO3 crystal particles in ceramics is too high, it may affect the electrical resistance at room temperature, and other crystal particles may become less, making it difficult to obtain desired characteristics. Therefore, the content of BaCO3 crystal particles is preferably 2.0 mass% or less, more preferably 1.8 mass% or less, and even more preferably 1.5 mass% or less. The lower limit of the content of BaCO3 crystal particles is not particularly limited, but is generally 0.1 mass%, preferably 0.2 mass%.

[0033] The ceramics used for the outer peripheral wall 11 and the partition walls 12 may further contain components that are conventionally added to PTC materials in addition to the above crystal particles. Such components include additives such as shifters, property improvers, metal oxides, and conductor powders, as well as unavoidable impurities.

[0034] From the viewpoint of reducing the environmental load, it is desirable that the ceramics used for the outer peripheral wall 11 and the partition wall 12 do not substantially contain lead (Pb). Specifically, the Pb content of the ceramics is preferably 0.01 mass% or less, more preferably 0.001 mass% or less, and even more preferably 0 mass%. With a low Pb content, for example, air heated by contact with the ceramics can be safely applied to living organisms such as humans. In addition, the Pb content of the ceramics is preferably less than 0.03 mass%, more preferably less than 0.01 mass%, and even more preferably 0 mass%, calculated as PbO. The lead content can be determined, for example, by X-ray fluorescence analysis, ICP-MS (inductively coupled plasma mass spectrometry), etc.

[0035] It is preferable that the ceramics used for the outer peripheral wall 11 and the partition walls 12 are substantially free of alkali metals that may affect the electrical resistance at room temperature. Specifically, the content of alkali metals in the ceramics is preferably 0.01 mass% or less, more preferably 0.001 mass% or less, and even more preferably 0 mass%. By controlling the content of alkali metals within such a range, it is possible to stably reduce the electrical resistance at room temperature. The content of alkali metals can be determined, for example, by X-ray fluorescence analysis, ICP-MS (inductively coupled plasma mass spectrometry), etc.

[0036] The Curie point of the material constituting the outer peripheral wall 11 and the partition wall 12 is preferably 100° C. or higher, more preferably 110° C. or higher, and even more preferably 125° C. or higher, from the viewpoint of efficiently heating air for heating. The upper limit of the Curie point is preferably 250° C., more preferably 225° C., even more preferably 200° C., and even more preferably 150° C., from the viewpoint of safety as a part placed in the vehicle interior or in the vicinity of the vehicle interior.

[0037] The Curie point of the material constituting the outer peripheral wall 11 and the partition walls 12 can be adjusted by the type and amount of the shifter added. For example, the Curie point of barium titanate (BaTiO3) is about 120°C, but 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 lower temperature side.

[0038] In the present invention, 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 Tabai Espec Corporation), and the change in electrical resistance of the sample relative to the temperature change when the temperature is raised from 10°C is measured using a DC resistance meter (e.g., multimeter 3478A, manufactured by YHP). 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 is taken as the Curie point.

[0039] (1-1-2. Thickness of partition wall 12 of honeycomb structure 10) From the viewpoint of suppressing the initial current, it is advantageous to make the current path small and increase the electrical resistance. Therefore, the thickness of the partition walls 12 in the honeycomb structure 10 is preferably 0.3 mm or less, more preferably 0.25 mm or less, and even more preferably 0.2 mm or less. On the other hand, from the viewpoint of ensuring the strength of the honeycomb structure 10, the thickness of the partition walls 12 is preferably 0.02 mm or more, more preferably 0.04 mm or more, and even more preferably 0.06 mm or more. The thickness of the partition walls 12 refers to the length of a line segment that crosses the partition walls 12 when the line segment connects the centers of gravity of adjacent cells 14 in a cross section perpendicular to the flow path direction of the cells 14. The thickness of the partition walls 12 refers to the average thickness of all the partition walls 12.

[0040] From the viewpoint of reinforcing the honeycomb structure 10, the thickness of the peripheral wall 11 is preferably 0.05 mm or more, more preferably 0.06 mm or more, and even more preferably 0.08 mm or more. However, from the viewpoint of increasing the electrical resistance and suppressing the initial current, and from the viewpoint of reducing the pressure loss during gas passage, the thickness of the peripheral wall 11 is preferably 1.0 mm or less, more preferably 0.5 mm or less, even more preferably 0.4 mm or less, and even more preferably 0.3 mm or less. The thickness of the peripheral wall 11 refers to the length in the normal direction of the side surface from the boundary between the peripheral wall 11 and the outermost cell 14 or partition wall 12 to the side surface of the honeycomb structure 10 in a cross section perpendicular to the flow path of the cell 14.

[0041] (1-1-3. Cell density and cell pitch of honeycomb structure 10) The cell density of the honeycomb structure 10 is preferably 93 cells / cm 2 Less than or equal to 62 cells / cm, more preferably 2 The cell pitch of the honeycomb structure 10 is preferably 1.0 mm or more, and more preferably 1.3 mm or more. By controlling the cell density or cell pitch within such a range, it is possible to suppress the ventilation resistance and thereby suppress the output of the blower. The lower limit of the cell density of the honeycomb structure 10 is not particularly limited, but is preferably 10 cells / cm. 2 , more preferably 20 cells / cm2 In addition, the upper limit of the cell pitch of the honeycomb structure 10 is not particularly limited, but is preferably 3.0 mm, and more preferably 2.0 mm. The cell density of the honeycomb structure 10 is a value obtained by dividing the number of cells by the area of ​​each end face of the honeycomb structure 10. Moreover, the cell pitch of the honeycomb structure 10 refers to the length of a line segment connecting the centers of gravity of two adjacent cells 14 on each end face of the honeycomb structure 10.

[0042] (1-1-4. Volume resistivity of honeycomb structure 10) The volume resistivity of the honeycomb structure 10 (the outer peripheral wall 11 and the partition walls 12) at room temperature (25° C.) is preferably 0.5 to 1000 Ω·cm. If the volume resistivity is in this range, it can be said that the electrical resistance at room temperature is low. By lowering the electrical resistance at room temperature, it is possible to ensure the heat generation performance required for heating and to suppress an increase in power consumption. In particular, when a pair of electrode layers 20 is provided on the surface of the outer peripheral wall 11 of the honeycomb structure 10, the inter-electrode distance becomes larger than when a pair of electrode layers 20 is provided on the end faces (first end face 13a, second end face 13b) of the honeycomb structure 10. However, by setting the volume resistivity in this range, it is possible to obtain the heat generation performance required for heating. When the maximum voltage applied from the power source is a high voltage in the range of 100 V to 800 V, the volume resistivity of the honeycomb structure at room temperature (25° C.) is preferably 10 to 1000 Ω·cm. When the maximum voltage applied from the power source is a low voltage in the range of 12 V to 60 V, the volume resistivity of the honeycomb structure at room temperature (25° C.) is preferably 0.5 to 100 Ω·cm. The volume resistivity of the honeycomb structure 10 is measured as follows. Two or more test pieces with dimensions of 30 mm×30 mm×15 mm are randomly cut and taken from the honeycomb structure 10. Then, the electrical resistance at the measurement temperature is measured by a two-terminal method, and the volume resistivity is calculated from the shape of the test piece. The average value of the volume resistivities of all the test pieces is taken as the measured value at the measurement temperature.

[0043] (1-1-5. Opening ratio of honeycomb structure 10) The opening ratio of the honeycomb structure 10 is preferably 80% or more, and more preferably 85% or more. By controlling the opening ratio within this range, the pressure loss during gas passage can be suppressed. The upper limit of the opening ratio of the honeycomb structure 10 is not particularly limited, but is preferably 95%, and more preferably 90%. By controlling the opening ratio within this range, the strength of the honeycomb structure 10 can be maintained. The opening ratio of the honeycomb structure 10 is a value obtained by dividing the area of ​​the cells 14 in a cross section perpendicular to the central axis X1 of the honeycomb structure 10 by the area of ​​the entire cross section (the total area of ​​the outer wall 11, the partition walls 12 and the cells 14), expressed as a percentage.

[0044] (1-2. Electrode layer 20) The heater element 100 according to the embodiment of the present invention includes a pair of electrode layers 20 disposed on the surface of the outer peripheral wall 11. The pair of electrode layers 20 are formed in a band shape extending parallel to the central axis X1 of the honeycomb structure 10. The pair of electrode layers 20 are disposed on the surface of the outer peripheral wall 11 so as to face each other across the long axis X2 passing through the center of gravity of the honeycomb structure 10 in a cross section perpendicular to the central axis X1 of the honeycomb structure 10. By applying a voltage through the pair of electrode layers 20 thus disposed, it becomes possible to pass electricity and generate heat in the honeycomb structure 10 by Joule heat.

[0045] The electrode layer 20 is not particularly limited, and may be, for example, a metal or alloy containing at least one selected from Cu, Ag, Al, Ni, and Si. An ohmic electrode layer capable of making ohmic contact with the outer peripheral wall 11 and / or the partition wall 12 having PTC characteristics may also be used. The ohmic electrode layer may be, for example, an ohmic electrode layer containing at least one selected from Au, Ag, and In as a base metal and at least one selected from Ni, Si, Ge, Sn, Se, and Te for n-type semiconductors as a dopant. The electrode layer 20 may be one layer or two or more layers. When the electrode layer 20 is two or more layers, the materials of the layers may be the same or different.

[0046] The thickness of the electrode layer 20 is not particularly limited, and can be appropriately set depending on the method for forming the electrode layer 20. Examples of the method for forming the electrode layer 20 include metal deposition methods such as sputtering, vapor deposition, electrolytic deposition, and chemical deposition. The electrode layer 20 can also be formed by applying an electrode paste and then baking it. Furthermore, the electrode layer 20 can also be formed by thermal spraying. The thickness of the electrode layer 20 is preferably about 5 to 30 μm in the case of baking an electrode paste, about 100 to 1000 nm in the case of dry plating such as sputtering and vapor deposition, about 10 to 100 μm in the case of thermal spraying, and about 5 to 30 μm in the case of wet plating such as electrolytic deposition and chemical deposition.

[0047] (1-3. External connection member 30) The heater element 100 according to the embodiment of the present invention includes a plate-shaped external connection member 30 disposed on the end side of each electrode layer 20 and in flat contact with each electrode layer 20. By disposing the plate-shaped external connection member 30 on each electrode layer 20 in this manner, it becomes easier to increase the amount of power supplied from the outside to the electrode layer 20, thereby improving heat generation performance. Here, in this specification, “the end side of each electrode layer 20” means a region from the end of each electrode layer 20 to 30% of the entire length of each electrode layer 20 in the direction of the major axis X2 passing through the center of gravity of the honeycomb structure 10. The external connection member 30 may be disposed on the end side of each electrode layer 20, and may not necessarily be in contact with the end of each electrode layer 20. For example, as shown in FIG. 4, a bent portion may be formed in the external connection member 30, and the bent portion may be connected to each electrode layer 20.

[0048] It is preferable that the external connection member 30 has a width substantially equal to the width of the end of the electrode layer 20 on the side where the external connection member 30 is disposed. With such a configuration, the contact area between the electrode layer 20 and the external connection member 30 becomes large, which enhances the effect of improving heat generation performance. In this specification, "approximately the same width as the width of the end of the electrode layer 20" means within ±20% of the width of the end of the electrode layer 20.

[0049] Each of the external connection members 30 is disposed on one end side of the electrode layer 20 parallel to the central axis X1. The end side on which the external connection members 30 are disposed may be the same side in the direction of the long axis X2 of the honeycomb structure 10 (for example, Figs. 1 to 5) or different (for example, Fig. 6). The end side is more preferably the same side. It is preferable that each of the external connection members 30 extends from the end side toward the outside in the same direction. Such a configuration allows for compactness when applied to the heater element 100.

[0050] The material of the external connection member 30 is not particularly limited, but may be, for example, a metal. As the metal, a simple metal or an alloy may be adopted, but from the viewpoint of corrosion resistance, electrical resistivity, and linear expansion coefficient, for example, an alloy containing at least one selected from the group consisting of Cr, Fe, Co, Ni, Cu, and Ti is preferable, and stainless steel, Fe-Ni alloy, and phosphor bronze are more preferable. The shape and size of the external connection member 30 are not particularly limited, and may be appropriately adjusted according to the structure of the heater unit to be manufactured.

[0051] The method of connecting the external connection member 30 and the electrode layer 20 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.

[0052] (1-4. Manufacturing method of heater element 100) Next, a method for manufacturing the heater element 100 according to the embodiment of the present invention will be described by way of example. When the material of the honeycomb structure 10 constituting the heater element 100 is ceramic, the manufacturing method of the honeycomb structure 10 includes a molding step and a firing step. In the forming step, a clay containing ceramic raw materials including BaCO3 powder, TiO2 powder, and powder of a rare earth nitrate or hydroxide is formed to produce a honeycomb formed body having a relative density of 60% or more. The ceramic raw material can be obtained by dry mixing each powder so as 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 necessary. The blending amount of components other than the ceramic raw materials is not particularly limited as long as the amount is such that the relative density of the honeycomb formed body is 60%.

[0053] 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 ceramic raw material (g / cm 3 ) x 100 The density of the honeycomb molded 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 3 ) can be calculated by dividing it by

[0054] The dispersion medium may be water or a mixed solvent of water and an organic solvent such as alcohol, with water being particularly preferred.

[0055] Examples of the binder include organic binders such as methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. In particular, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose in combination. The binder may be used alone or in combination of two or more kinds, but it is preferable that the binder does not contain an alkali metal element.

[0056] Examples of the plasticizer include polyoxyalkylene alkyl ethers, polycarboxylic acid polymers, and alkyl phosphate esters.

[0057] 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 kinds.

[0058] The honeycomb formed body can be produced by extruding a clay. In the extrusion molding, a die having a desired overall shape, cell shape, partition wall thickness, cell density, etc. can be used.

[0059] The relative density of the honeycomb molded body obtained by extrusion molding is 60% or more, preferably 61% or more. By controlling the relative density of the honeycomb molded body within such a range, it is possible to densify the honeycomb molded body and reduce the electrical resistance at room temperature. The upper limit of the relative density of the honeycomb molded body is not particularly limited, but is generally 80%, preferably 75%.

[0060] 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 quickly and uniformly dry the entire molded body.

[0061] The firing step includes holding the material at 1150-1250° C., then raising the temperature to a maximum temperature of 1360-1430° C. at a heating rate of 20-500° C. / hour, and holding the temperature for 0.5-10 hours. By holding the honeycomb formed body at a maximum temperature of 1360 to 1430° C. for 0.5 to 10 hours, it is possible to obtain a honeycomb structure 10 mainly composed of BaTiO3-based crystal grains in which a portion of Ba has been substituted with a rare earth element. Moreover, by maintaining the temperature at 1150 to 1250° C., Ba2TiO4 crystal particles generated during the firing process are easily removed, so that the honeycomb structure 10 can be densified. Furthermore, by setting the heating rate from 1150-1250°C to the maximum temperature of 1360-1430°C at 20-500°C / hour, 1.0-10.0 mass% of Ba6Ti 17 O 40 Crystal grains can be generated in the honeycomb structure 10 .

[0062] The holding time at 1150 to 1250° C. is not particularly limited, but is preferably 0.5 to 10 hours. By setting the holding time in this range, Ba2TiO4 crystal particles formed during the firing process can be stably and easily removed.

[0063] The firing step preferably includes holding at 900 to 950° C. for 0.5 to 5 hours. By holding at 900 to 950° C. for 0.5 to 5 hours, BaCO3 is efficiently decomposed, and a honeycomb structure 10 having a predetermined composition can be easily obtained.

[0064] 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 in order to completely decompose the organic components. Moreover, it is preferable that the firing step be performed in an air atmosphere from the viewpoints of controlling electrical characteristics and reducing manufacturing costs. The firing furnace used in the firing step and the degreasing step is not particularly limited, but an electric furnace, a gas furnace, or the like can be used.

[0065] An electrode layer 20 is formed on a predetermined surface of the outer wall 11 of the honeycomb structure 10 obtained in this manner. The electrode layer 20 can be formed by the above-mentioned method. The electrode layer 20 may be a single layer, or may be a multiple layer having different compositions.

[0066] Next, the external connection member 30 is connected to the electrode layer 20. As a method for connecting the electrode layer 20 and the external connection member 30, the above-mentioned methods can be used.

[0067] (1-5. How to use the heater element 100) The heater element 100 according to the embodiment of the present invention can generate heat in the honeycomb structure 10 by applying a voltage from the external connection member 30 via the pair of electrode layers 20. From the viewpoint of rapid heating, the applied voltage is preferably 200 V or more, and more preferably 250 V or more.

[0068] When the heater element 100 is generating heat due to the application of a voltage, the gas can be heated by flowing the gas through the cell 14. The temperature of the gas flowing into the cell 14 can be, for example, -60°C to 20°C, and typically -10°C to 20°C.

[0069] The heater element 100 according to the embodiment of the present invention can improve the heat generation performance by arranging the electrode layer 20 and the external connection member 30 as described above, since it is easy to increase the amount of power supplied from the outside to the electrode layer 20. In addition, the heater element 100 according to the embodiment of the present invention has a simpler structure than the existing heater element in which the PTC element and the aluminum fin are integrated via an insulating ceramic plate, and can suppress the heater unit from becoming large. In addition, the existing heater element has an insufficient gas temperature rise rate (temperature rise time) because the PTC element does not directly contact the gas, but the heater element 100 according to the embodiment of the present invention can increase the gas temperature rise rate because the honeycomb structure 10, in which the outer peripheral wall 11 and the partition wall 12 are made of a material having PTC properties, directly contacts the gas.

[0070] In another aspect, the heater element according to the embodiment of the present invention can also be suitably used as a heater element for purifying the interior of a vehicle. FIG. 9 shows a schematic enlarged partial cross-sectional view perpendicular to the central axis of the honeycomb structure 10 of the heater element used in this embodiment. As shown in Fig. 9, the heater element used in this embodiment further includes a functional material-containing layer 40 provided on the surface of the partition wall 12 of the honeycomb structure 10. By using a heater element having such a configuration, the components to be removed, such as water vapor, carbon dioxide, and odor components, can be captured by the functional material-containing layer 40 by circulating air containing the components to be removed through the cells 14. Note that the heater element used in this embodiment has the same configuration as the heater element 100 described above, except for the fact that it further includes the functional material-containing layer 40, and therefore detailed description thereof will be omitted.

[0071] In addition, in the heater element used in this embodiment, a pair of electrode layers 20 are formed in a band shape extending parallel to the central axis X1, and are arranged on the surface of the outer peripheral wall 11 so as to face each other across the long axis X2 passing through the center of gravity of the honeycomb structure 10 in a cross section perpendicular to the central axis X1. Therefore, compared with a mode in which a pair of electrode layers 20 are provided on both end faces (first end face 13a, second end face 13b) of the honeycomb structure 10, the honeycomb structure 10 can be heated uniformly, and the functional material-containing layer 40 can be heated uniformly, making it possible to effectively exhibit the function of the functional material. The reason why such an effect occurs is presumed to be as follows. In a heater element in which a pair of electrode layers 20 are provided on both end faces (first end face 13a, second end face 13b) of the honeycomb structure 10, when air is introduced from the inlet (for example, the first end face 13a) side of the honeycomb structure 10, the temperature of the honeycomb structure 10 on the inlet side is cooled. As a result, the honeycomb structure 10 is not heated uniformly, and the functional material on the inlet side is not heated to its activation temperature, making it difficult for the functional material to exert its function. In response to this, by providing a pair of electrode layers 20 on the surface (side surface) of the outer peripheral wall 11, when a voltage is applied, the honeycomb structure 10 on the cold inlet (e.g., first end face 13a) side has low resistance, causing current to concentrate, while the relatively warm outlet (e.g., second end face 13b) side has high resistance, causing the current to be restricted. This makes it easier to heat the entire honeycomb structure 10 uniformly, and it is believed that the function of the functional material can be exerted effectively.

[0072] The functional material contained in the functional material-containing layer 40 is not particularly limited, but an adsorbent, a catalyst, or the like can be used. The functional material-containing layer 40 preferably contains, for example, an adsorbent material. By containing the adsorbent material, it is possible to capture the components to be removed in the air in the vehicle compartment. The functional material-containing layer 40 may contain a catalyst. The use of a catalyst can purify the components to be removed. In addition, an adsorbent and a catalyst may be used in combination for the purpose of enhancing the function of the adsorbent in capturing the components to be removed.

[0073] The adsorbent preferably has a function of adsorbing the components to be removed (for example, water vapor, carbon dioxide, odor components), and more preferably has a function of being able to adsorb the components to be removed at -20 to 40°C and desorb them at a high temperature of 60°C or higher. Examples of adsorbents having such a function include zeolite, silica gel, activated carbon, alumina, silica, low-crystalline clay, and amorphous aluminum silicate complexes. The type of adsorbent may be appropriately selected depending on the type of the components to be removed. The catalyst preferably has a function capable of promoting an oxidation-reduction reaction. Examples of catalysts having such a function include metal catalysts such as Pt, Pd, and Ag, and oxide catalysts such as CeO2 and ZrO2.

[0074] Components to be removed from the air in the vehicle cabin include, for example, water vapor, carbon dioxide, and odor components. Specific examples of odor components include ammonia, acetic acid, isovaleric acid, nonenal, formaldehyde, toluene, xylene, paradichlorobenzene, ethylbenzene, styrene, chlorpyrifos, di-n-butyl phthalate, tetradecane, di-2-ethylhexyl phthalate, diazinon, acetaldehyde, and N-methylcarbamate-2-(1-methylpropyl)phenyl.

[0075] In the honeycomb structure 10 of the heater element used in this embodiment, the thickness of the partition walls 12 is preferably 0.125 mm or less, more preferably 0.10 mm or less, and further preferably 0.08 mm or less, from the viewpoint of supporting a sufficient amount of functional material in the honeycomb structure 10. From the same viewpoint, the cell density is preferably 100 cells / cm. 2 Less than or equal to 70 cells / cm, more preferably 70 cells / cm 2 Less than 65 cells / cm, more preferably 65 cells / cm 2 and the cell pitch is preferably 1.0 mm or more, more preferably 1.2 mm or more, and further preferably 1.3 mm or more.

[0076] (2. Heater unit) The heater unit according to the embodiment of the present invention can be suitably used as a heater unit for heating the passenger compartment of a vehicle. In particular, the heater unit according to the embodiment of the present invention uses a heater element 100 with high heat generation performance, so that the heat generation performance of the heater unit can be improved. In addition, since the heater element 100 can be made compact, it is possible to prevent the heater unit from becoming large.

[0077] FIG. 10 is a schematic front view of the heater unit according to the embodiment of the present invention as viewed from the first end face side of the heater element. 10, a heater unit 600 according to an embodiment of the present invention includes two or more heater elements 100. In the heater unit 600, the heater elements 100 are stacked and arranged so that the surfaces of the outer peripheral walls 11 of the honeycomb structure 10, including the long sides 16 of the first end face 13a and the second end face 13b, face each other. With this configuration, a compact heater unit 600 can be manufactured.

[0078] The heater unit 600 according to the embodiment of the present invention may further include a housing (housing member) 610. The material of the housing 610 is not particularly limited, and examples thereof include metal, resin, etc. Among them, the material of the housing 610 is preferably resin. By using the housing 610 made of resin, electric shock can be suppressed even without grounding. The shape and size of the housing 610 are not particularly limited, and may be the same as those of an existing heater unit.

[0079] The heater unit 600 according to the embodiment of the present invention may further include an insulating material 620 disposed between the stacked heater elements 100. With this configuration, electrical shorts between the multiple heater elements 100 can be suppressed. The insulating material 620 may be a plate, mat, cloth, or the like made of an insulating material such as alumina or ceramics.

[0080] The heater unit 600 according to the embodiment of the present invention has a wiring structure capable of controlling the heater element 100. Specifically, the heater unit 600 according to the embodiment of the present invention may further include wiring 630 connected to the external connection member 30 of the heater element 100. The wiring structure is not particularly limited, but as shown in Fig. 10, the wiring structure can be such that each of the heater elements 100 can be controlled independently. Specifically, wiring 630 can be connected to each of the external connection members 30 of the heater elements 100. The wiring 630 is connected to an external power source (not shown). By using such a wiring structure, each of the heater elements 100 can be controlled independently, making it possible to finely adjust the temperature.

[0081] The wiring structure may be a parallel wiring structure capable of collectively controlling two or more heater elements 100, as shown in Fig. 11. Specifically, a parallel wiring 640a may be connected to one of the external connection members 30 of each heater element 100, and one parallel wiring 640b may be connected to the other external connection member 30. By using such a wiring structure, the power consumption of the heater unit 700 can be reduced.

[0082] 12, the electrode layer 20 between the heater elements 100 arranged in a stacked arrangement may be one electrode layer 20 common to the heater elements 100 arranged in a stacked arrangement, and a parallel wiring structure that can control two or more heater elements 100 collectively may be used. Specifically, the external connection member 30 is disposed at the end of the electrode layer 20, and a parallel wiring 640a is connected to one external connection member 30 of each heater element 100, and one parallel wiring 640b is connected to the other external connection member 30. By adopting such a structure, it is not necessary to arrange an insulating material 620 between the heater elements 100 arranged in a stacked arrangement, so that the heater unit 800 can be made compact and power consumption can be reduced.

[0083] (3. Heater System) The heater system according to the embodiment of the present invention can be suitably used as a heater system for heating the passenger compartment of a vehicle. In particular, the heater system according to the embodiment of the present invention uses a heater unit 600 with high heat generation performance, so that the heat generation performance of the heater system can be improved. In addition, since the heater unit 600 can be made compact, it is possible to prevent the heater system from becoming large. Note that heater units 700 and 800 may be used instead of the heater unit 600.

[0084] FIG. 13 is a schematic diagram showing a configuration example of a heater system according to an embodiment of the present invention. As shown in FIG. 13, a heater system 900 according to an embodiment of the present invention includes a heater unit 600 according to an embodiment of the present invention, inlet pipes 920a, 920b connecting an outside air introduction section or a vehicle interior 910 with an inlet 650 of the heater unit 600, a battery 940 for applying voltage to the heater unit 600, and an outlet pipe 930 connecting an outlet 660 of the heater unit 600 with the vehicle interior 910.

[0085] The heater unit 600 can be configured, for example, to be connected to a battery 940 by an electric wire 950, and the heater unit 600 can be configured to generate heat by turning on a power switch in between the wires.

[0086] A vapor compression heat pump 960 can be installed upstream of the heater unit 600. In the heater system 900, the vapor compression heat pump 960 is configured as a main heating device, and the heater unit 600 is configured as an auxiliary heater. The vapor compression heat pump 960 can include a heat exchanger including an evaporator 961 that absorbs heat from the outside and evaporates a refrigerant during cooling, and a condenser 962 that liquefies a refrigerant gas and releases heat to the outside during heating. The vapor compression heat pump 960 is not particularly limited, and one known in the art can be used.

[0087] A blower 970 may be installed upstream and / or downstream of the heater unit 600. From the viewpoint of ensuring safety by arranging high-voltage components as far away from the vehicle interior 910 as possible, the blower 970 is preferably installed upstream of the heater unit 600. When the blower 970 is driven, air flows into the heater unit 600 from inside or outside the vehicle interior 910 through the inlet pipes 920a and 920b. The air is heated while passing through the heater unit 600 generating heat. The heated air flows out of the heater unit 600 and is sent into the vehicle interior 910 through the outlet pipe 930. The outlet of the outlet pipe 930 may be located near the feet of the occupant so that the heating effect is particularly high in the vehicle interior 910, or the outlet of the outlet pipe 930 may be located inside the seat to heat the seat from the inside, or the outlet may be located near the window to have the effect of suppressing fogging of the window.

[0088] The inlet pipe 920a and the inlet pipe 920b join together midway. Valves 921a and 921b can be installed in the inlet pipe 920a and the inlet pipe 920b, respectively, upstream of the joining point. By controlling the opening and closing of the valves 921a and 921b, it is possible to switch between a mode in which outside air is introduced into the heater unit 600 and a mode in which air in the vehicle interior 910 is introduced into the heater unit 600. For example, when the valve 921a is opened and the valve 921b is closed, the mode in which outside air is introduced into the heater unit 600 is selected. It is also possible to open both the valves 921a and 921b to introduce the outside air and the air in the vehicle interior 910 into the heater unit 600 at the same time. EXAMPLES

[0089] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0090] Example 1 A heater element A1 was produced, the cross section of which perpendicularly intersecting the central axis of the honeycomb bonded body has the shape shown in Fig. 14. Specifically, the heater element A1 was produced as follows. BaCO3 powder, TiO2 powder, and La(NO3)3·6H2O powder were prepared as ceramic raw materials. These powders were weighed so that the specified composition would be obtained after firing, and then dry-mixed to obtain a mixed powder. Dry mixing was carried out for 30 minutes. Next, water, binder, plasticizer, and dispersant were added in appropriate amounts in the range of 3 to 30 parts by weight in total to 100 parts by mass of the obtained mixed powder, and kneaded to obtain a clay body having a relative density of 64.8% after extrusion molding. Methylcellulose was used as the binder. Polyoxyalkylene alkyl ether was used as the plasticizer and dispersant. This clay was put into an extrusion molding machine, and after firing, it was extruded using a specified die so that the cross section perpendicular to the central axis would have a honeycomb segment shape as shown in Figure 14, thereby obtaining a honeycomb molded body (dimensions after firing: 32 mm x 32 mm x 14 mm). The density of the honeycomb molded body was then measured according to the method described above. Next, the obtained honeycomb molded body was subjected to dielectric drying and hot air drying, and then degreased (450°C x 4 hours) in an air atmosphere in a firing furnace, and then fired in an air atmosphere to obtain a honeycomb segment. The firing was performed by sequentially holding at 950°C for 1 hour, increasing the temperature to 1200°C, holding at 1200°C for 1 hour, increasing the temperature to 1400°C (maximum temperature) at 200°C / hour, and holding at 1400°C for 2 hours.

[0091] Details of the obtained honeycomb segment are as follows. Content of BaTiO3 crystal particles: 95.0% by mass Ba6Ti 17 O 40 Crystal particle content: 4.0% by mass BaCO3 crystal particle content: 1.0% by mass La atomic ratio (x value) of BaTiO3 crystal particles: 0.001 (Ba+La) / Ti ratio of BaTiO3 crystal particles: 1.030 Average crystal grain size of BaTiO3 crystal grains: 20μm

[0092] The content of each crystal grain was identified using an X-ray diffractometer. A multi-function powder X-ray diffractometer (D8Advance, manufactured by Bruker) was used as the X-ray diffractometer. The conditions for the X-ray diffraction measurement were CuKα radiation source, 10 kV, 20 mA, and 2θ=5 to 100°. The obtained X-ray diffraction data was analyzed by the Rietveld method using the analysis software TOPAS (manufactured by BrukerAXS) to identify the crystal grains. The content of each crystal grain was measured using an X-ray diffractometer. The same X-ray diffractometer and analysis software as above were used, and the content of each crystal grain was determined by the Rietveld method. The chemical composition of the ceramics was analyzed by ICP emission spectroscopy to determine the atomic ratios of elements such as La, Ba, and Ti. The average crystal grain size of the ceramics was measured according to the above-mentioned method. SEM observation was performed using a Hitachi High-Technologies Corporation S-3400N with an accelerating voltage of 15 kV and a magnification of 3000. The above measurement conditions were the same in the following examples.

[0093] Next, five of the above honeycomb segments were prepared, and a bonding material was applied to the sides of the honeycomb segments to bond them together to obtain a honeycomb bonded body. The bonding material was a ceramic material with a solvent such as water added to make a paste.

[0094] Details of the obtained honeycomb bonded body are as follows. The physical properties were measured by the above-mentioned methods. Shape of honeycomb joint in cross section perpendicular to the central axis: Rectangular Shape of cell in cross section perpendicular to the central axis: Square Partition thickness: 0.10mm Cell density: 64 cells / cm 2 Cell pitch: 1.27mm Cross section perpendicular to the cell extension direction: 32mm x 180mm Length of cell extension: 14mm End surface area: 57.6cm 2 Angle of bulkhead to major axis: 0° and 90° Volume resistivity at room temperature (25°C): 14 Ω cm Opening ratio: 85% Curie point: 120℃

[0095] Next, electrode layers were formed on both sides of the outer peripheral wall including the long sides of the rectangular cross section of the honeycomb joint body. As the electrode layers, first, an Al-Ni electrode paste was applied to both sides of the outer peripheral wall, and then a silver electrode paste was applied and baked at 700°C to form an Al-Ni electrode layer and a silver electrode layer. Next, a plate-shaped external connection member made of phosphor bronze was connected to one end side of each electrode layer to obtain a heater element A1.

[0096] Example 2 A heater element A2 was produced in the same manner as in Example 1, except that a honeycomb joined body having a shape as shown in Fig. 8 was used as the honeycomb joined body. Specifically, the heater element A2 was produced as follows. BaCO3 powder, TiO2 powder, and La(NO3)3·6H2O powder were prepared as ceramic raw materials. These powders were weighed so that the specified composition would be obtained after firing, and then dry-mixed to obtain a mixed powder. Dry mixing was carried out for 30 minutes. Next, water, binder, plasticizer, and dispersant were added in appropriate amounts in the range of 3 to 30 parts by weight in total to 100 parts by mass of the obtained mixed powder, and kneaded to obtain a clay body having a relative density of 63.6% after extrusion molding. Methylcellulose was used as the binder. Polyoxyalkylene alkyl ether was used as the plasticizer and dispersant. This clay was put into an extrusion molding machine, and after firing, it was extrusion molded using a specified die so that the cross section perpendicular to the central axis would become a honeycomb segment with a shape as shown in Figure 8, thereby obtaining a honeycomb molded body (dimensions after firing: 32 mm x 32 mm x 14 mm). The density of the honeycomb molded body was then measured according to the method described above. Next, the obtained honeycomb molded body was subjected to dielectric drying and hot air drying, and then degreased (450°C x 4 hours) in an air atmosphere in a firing furnace, and then fired in an air atmosphere to obtain a honeycomb segment. The firing was performed by sequentially holding at 950°C for 1 hour, increasing the temperature to 1200°C, holding at 1200°C for 1 hour, increasing the temperature to 1400°C (maximum temperature) at 50°C / hour, and holding at 1400°C for 2 hours.

[0097] Details of the obtained honeycomb segment are as follows. BaTiO3 crystal particle content: 97.3 mass% Ba6Ti 17 O 40 Crystal particle content: 3.9% by mass BaCO3 crystal particle content: 1.0% by mass La atomic ratio (x value) of BaTiO3 crystal particles: 0.002 (Ba+La)Ti ratio of BaTiO3 crystal particles: 1.010 Average crystal grain size of BaTiO3 crystal grains: 8μm

[0098] Next, five of the above honeycomb segments were prepared, and a bonding material was applied to the side surfaces of the honeycomb segments to bond them together, thereby obtaining a honeycomb bonded body as shown in Fig. 8. The bonding material used was a paste made by adding a solvent such as water to a ceramic material.

[0099] Details of the obtained honeycomb bonded body are as follows. The physical properties were measured by the above-mentioned methods. Shape of honeycomb joint in cross section perpendicular to the central axis: Rectangular Shape of cell in cross section perpendicular to the central axis: Square Partition thickness: 0.10mm Cell density: 64 cells / cm 2 Cell pitch: 1.27mm Cross section perpendicular to the cell extension direction: 32mm x 180mm Length of cell extension: 14mm End surface area: 57.6cm 2 Angle of bulkhead to major axis: 45° Volume resistivity at room temperature (25°C): 30 Ω cm Opening ratio: 85% Curie point: 120℃

[0100] Next, electrode layers were formed on both sides of the outer peripheral wall including the long sides of the rectangular cross section of the honeycomb joint body. As the electrode layers, first, an Al-Ni electrode paste was applied to both sides of the outer peripheral wall, and then a silver electrode paste was applied and baked at 700°C to form an Al-Ni electrode layer and a silver electrode layer. Next, a plate-shaped external connection member made of phosphor bronze was connected to one end side of each electrode layer to obtain a heater element A2.

[0101] Example 3 A heater element A3 having a cross section perpendicular to the central axis of a honeycomb structure as shown in Fig. 2 was produced using the same clay as in Example 1. Specifically, the heater element A3 was produced as follows. A honeycomb structure was obtained under the same conditions as in Example 1, except that extrusion molding was performed so that the cross section perpendicular to the central axis had a shape as shown in FIG.

[0102] Details of the obtained honeycomb structure are as follows. The physical properties were measured by the above-mentioned methods. Shape of honeycomb structure in cross section perpendicular to the central axis: rectangular Shape of cell in cross section perpendicular to the central axis: Square Partition thickness: 0.13mm Cell density: 64 cells / cm 2 Cell pitch: 1.30mm Cross section perpendicular to the cell extension direction: 32mm x 175mm Length of cell extension: 14mm End surface area: 57.6cm 2 Angle of bulkhead to major axis: 45° Volume resistivity at room temperature (25°C): 14 Ω cm Opening ratio: 85% Curie point: 120℃

[0103] Next, electrode layers were formed on both sides of the outer peripheral wall including the long sides of the rectangular cross section of the honeycomb structure. As the electrode layers, first, an Al-Ni electrode paste was applied to both sides of the outer peripheral wall, and then a silver electrode paste was applied and baked at 700°C to form an Al-Ni electrode layer and a silver electrode layer. Next, a plate-shaped external connection member made of phosphor bronze was connected to one end side of each electrode layer to obtain a heater element A3.

[0104] (Heater element evaluation) The heater elements A1 and A2 obtained above were placed in an evaluation box having a gas inlet and an outlet as shown in Fig. 15. A current heating test was performed by applying 200 V to the heater elements A1 and A2 while flowing gas into the evaluation box from the gas inlet at 400 L / min. In the resistance heating test, the gas temperature at the gas outlet was measured at a position 100 mm away from the ends of the heater elements A1 and A2. As a result, heater element A1 reached 60°C in 10 seconds, and heater element A2 reached 80°C in 10 seconds. A similar test was performed on heater element A3 with a gas flow rate of 400 L / min and an applied voltage of 200 V, and the temperature reached 80° C. in 10 seconds.

[0105] In the resistance heating test, one cycle consisted of one hour of resistance heating and 30 minutes of cooling by gas flow at room temperature (25°C), and the resistance between the external connection members was measured after 100 cycles. As a result, the resistance of heater element A1 doubled from the initial value (100Ω) to 200Ω, while that of heater element A2 remained at 100Ω.

[0106] In addition, 2.5 seconds after the voltage was applied during the electrical heating test, the current density distribution of the honeycomb bonded bodies constituting the heater elements A1 and A2 was estimated in a cross section 1 mm from the end faces of the honeycomb bonded bodies. The results are shown in Fig. 16. In Fig. 16, (A) shows the current density distribution of the honeycomb structure of the heater element A1, and (B) shows the current density distribution of the honeycomb structure of the heater element A2. As shown in Fig. 16, in the honeycomb bonded body of the heater element A2, current flowed almost uniformly through all the partition walls, whereas in the honeycomb bonded body of the heater element A1, current was concentrated in the partition walls at 90° to the long axis, and current did not flow sufficiently through the partition walls at 0° (parallel) to the long axis. Therefore, it is considered that the heater element A2 can heat the honeycomb bonded body more uniformly than the heater element A1. Furthermore, as a result of continuing application of electric power in the electric current heating test, the heater element A1 caused deformation and cracks in the partition walls near the electrode layer, whereas the heater element A2 did not cause such deformation and cracks. Therefore, it is considered that the heater element A2 can further suppress deformation and cracks in the partition walls of the honeycomb structure.

[0107] As can be seen from the above results, the present invention can provide a heater element for heating a vehicle interior that can increase the amount of power supplied from outside and improve heat generation performance, as well as a heater unit and heater system for heating a vehicle interior that use this heater element. In addition, the present invention can provide a heater element that can also be used for purifying the vehicle interior. [Explanation of symbols]

[0108] 10 Honeycomb structure 11 Peripheral wall 12 Bulkhead 13a First end surface 13b Second end face 14 Cells 15 Short Side 16 Long side 17 Honeycomb joint 18 Honeycomb Segments 19 Bonding layer 20 electrode layer 30 External connection parts 40 Functional material containing layer 100,200,300,400,500 Heater elements 600 Heater Unit 610 Case 620 Insulation Materials 630 Wiring 640a,640b parallel wiring 650 Inlet 660 Outlet 700,800 heater units 900 Heater System 910 Cabin 920a,920b Inflow piping 921a, 921b Valve 930 Outlet pipe 940 Battery 950 Electric wire 960 Vapor Compression Heat Pump 961 Evaporator 962 Condenser 970 Blower X1 center axis X2 long axis X3 short axis

Claims

1. A honeycomb structure including an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells that form a flow path from a first end surface to a second end surface, the outer peripheral wall and the partition walls being made of a material having a PTC characteristic; A pair of electrode layers disposed on a surface of the outer peripheral wall; A heater element for heating a vehicle interior, comprising: The honeycomb structure has a shape having a long axis and a short axis in a cross section perpendicular to a central axis, the pair of electrode layers are formed in a band shape extending parallel to the central axis, and are arranged on the surface of the outer peripheral wall so as to face each other across a long axis passing through the center of gravity of the honeycomb structure in a cross section perpendicular to the central axis, The heater element further includes a plate-shaped external connection member disposed on an end side of each electrode layer parallel to the central axis and in flat contact with each electrode layer, a heater element in which the end side of each of the electrode layers parallel to the central axis is a region from the end of each of the electrode layers to 30% of the total length of each of the electrode layers in the long axis direction passing through the center of gravity of the honeycomb structure, the external connection members extend in the same direction from the end side of each of the electrode layers parallel to the central axis toward the outside, and the entire external connection member has a width approximately the same as the width of the end of the electrode layer.

2. 2. The heater element according to claim 1, wherein the honeycomb structure has a rectangular cross section perpendicular to the central axis, and the pair of electrode layers are disposed on both sides of the outer peripheral wall including the long sides of the rectangular cross section.

3. The heater element according to claim 2, wherein the rectangular cross section has a ratio of the length of the short side to the length of the long side of 1:2 to 1:

15.

4. The heater element according to any one of claims 1 to 3, wherein the honeycomb structure has no partition walls parallel to the major axis in a cross section perpendicular to the central axis.

5. The heater element according to any one of claims 1 to 4, wherein in a cross section of the honeycomb structure perpendicular to the central axis, an angle of the partition walls with respect to the major axis is 30 to 60°.

6. The heater element according to any one of claims 1 to 5, wherein the partition walls of the honeycomb structure form a hexagonal cell shape in a cross section perpendicular to the central axis.

7. The honeycomb structure has a partition wall thickness of 0.3 mm or less and a cell density of 93 cells / cm 2 The heater element according to any one of claims 1 to 6, wherein the cell pitch is 1.0 mm or more.

8. The heater element according to any one of claims 1 to 7, wherein the outer peripheral wall and the partition walls have a volume resistivity of 0.5 to 1000 Ω·cm at room temperature.

9. The heater element according to any one of claims 1 to 8, wherein the outer peripheral wall and the partition walls are made of a material containing barium titanate as a main component and substantially no lead.

10. The heater element according to any one of claims 1 to 9, wherein the honeycomb structure is a honeycomb joined body having two or more honeycomb segments and a joining layer joining the honeycomb segments.

11. The heater element according to any one of claims 1 to 10, wherein the honeycomb structure has an opening ratio of 80% or more.

12. A heater unit for heating a vehicle interior, comprising two or more heater elements according to any one of claims 1 to 11, A heater unit in which the heater elements are stacked and arranged so that surfaces of the outer peripheral walls of the honeycomb structures, which include longer sides of the first end face and the second end face, face each other.

13. The heater unit according to claim 12 , wherein an insulating material is disposed between the heater elements arranged in a stacked manner, and the heater unit has a wiring structure capable of independently controlling each of the heater elements.

14. The heater unit according to claim 12 , wherein an insulating material is disposed between the heater elements arranged in a stacked manner, and the heater unit has a parallel wiring structure capable of collectively controlling two or more of the heater elements.

15. The heater unit according to claim 12, wherein the electrode layer between the heater elements arranged in a stacked arrangement is one electrode layer common to the heater elements arranged in a stacked arrangement, and has a parallel wiring structure capable of collectively controlling two or more of the heater elements.

16. The heater unit according to any one of claims 12 to 15, An inlet pipe communicating an outside air introduction portion or a vehicle interior with an inlet of the heater unit; a battery for applying a voltage to the heater unit; and An outlet pipe that connects the outlet of the heater unit to the vehicle compartment A heater system for heating a vehicle interior.

17. A honeycomb structure including an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells that form a flow path from a first end surface to a second end surface, the outer peripheral wall and the partition walls being made of a material having a PTC characteristic; A pair of electrode layers disposed on a surface of the outer peripheral wall; a functional material-containing layer provided on a surface of the partition wall; A heater element for purifying a vehicle interior, comprising: The honeycomb structure has a shape having a long axis and a short axis in a cross section perpendicular to a central axis, the pair of electrode layers are formed in a band shape extending parallel to the central axis, and are arranged on the surface of the outer peripheral wall so as to face each other across a long axis passing through the center of gravity of the honeycomb structure in a cross section perpendicular to the central axis, The heater element further includes a plate-shaped external connection member disposed on an end side of each electrode layer parallel to the central axis and in flat contact with each electrode layer, a heater element in which the end side of each of the electrode layers parallel to the central axis is a region from the end of each of the electrode layers to 30% of the total length of each of the electrode layers in the long axis direction passing through the center of gravity of the honeycomb structure, the external connection members extend in the same direction from the end side of each of the electrode layers parallel to the central axis toward the outside, and the entire external connection member has a width approximately the same as the width of the end of the electrode layer.

18. The heater element according to claim 17, wherein the functional material-containing layer contains a functional material having a function of adsorbing one or more substances selected from the group consisting of water vapor, carbon dioxide, and odor components.

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