Gas sensor element, gas sensor and method for manufacturing a gas sensor element

Abstract

A gas sensor element (10, 310) comprising a first ceramic composite layer (111) with a plate-like first electrolyte part (121) formed from a solid electrolyte ceramic and having an electrolyte outer circumferential surface (125), and a plate-like first surrounding part (112) formed from an insulating ceramic or a mixture of an insulating ceramic and the solid electrolyte ceramic and having a through-hole inner circumferential surface (115) forming a through-hole (112h) extending in a thickness direction (DT), wherein the electrolyte part (121) is arranged in the through-hole (112h) and the electrolyte outer circumferential surface (125) of the first electrolyte part (121) is in contact with the through-hole inner circumferential surface (115) of the first surrounding part (112), wherein mutually facing contact surfaces (115k, 125k) of the electrolyte outer circumferential surface (125) of the first electrolyte part (121) and the through-hole inner circumferential surface (115) of the first surrounding part (112) are inclined accordingly towards the outside of the first electrolyte part (121), while moving to one side (DT1) with respect to the thickness direction (DT) and are completely in close contact with each other, and in a vertical cross-section along the thickness direction (DT) of the electrolyte part (121) a main surface (124) of the electrolyte part (121) and the contact surface (125k) of the electrolyte outer circumferential surface (125) form an angle (θ) which is equal to or greater than 45° but equal to or less than 80° (45° ≤ θ ≤ 80°).

Description

1. Field of the invention

[0001] The present invention relates to a gas sensor element for detecting gas to be measured, a gas sensor comprising the gas sensor element, and a method for manufacturing the gas sensor element. 2. State of the art

[0002] Patent document 1 discloses, for example, a gas sensor element with a layer (a ceramic composite layer, which is described below) configured such that a solid electrolyte body (an electrolyte part, which is described below) is arranged in a through-hole formed in an insulating element (a surrounding part, which is described below). [Patent document 1] JP 2007 - 278 941 A

[0003] Further relevant state of the art is discussed in the following documents: DE 10 2012 213 690 A1, US 2005 / 0 189 222 A1 and DE 10 2007 057 430 A1. 3. Problems to be solved by the invention

[0004] In the gas sensor element from patent document 1, however, the outer circumferential surface (an electrolyte outer circumferential surface, which will be described later) of the solid electrolyte body (electrolyte part) is in contact with the inner circumferential surface (a through-hole inner circumferential surface, which will be described below) of the through-hole, which is substantially perpendicular to the surface of the insulating element (surrounding parts).Consequently, since the contact length along the thickness direction between the electrolyte outer circumferential surface of the electrolyte part and the through-hole inner circumferential surface of the surrounding part is small, a sufficient contact length along the thickness direction between the electrolyte outer circumferential surface of the electrolyte part and the through-hole inner circumferential surface of the surrounding part cannot be guaranteed during the manufacture of the gas sensor element, which potentially results in the problem that the opposing main surfaces of the electrolyte part are in contact with each other via a gap formed between the electrolyte outer circumferential surface and the through-hole inner circumferential surface. OVERVIEW OF THE INVENTION

[0005] The present invention was conceived with regard to the aforementioned problem, and it is an object of the invention to provide a gas sensor element which achieves high reliability by reducing a problem arising from the formation of a gap between the electrolyte part and the surrounding part, as well as a gas sensor comprising the gas sensor element and a method for manufacturing the gas sensor element.

[0006] The preceding problem has been solved in one aspect by a gas sensor element having the features of claim 1. Furthermore, a method having the features of claim 6 is specified. Further advantageous embodiments are defined in the dependent claims.

[0007] (1) A gas sensor element is provided comprising a first composite ceramic layer. The first composite ceramic layer has a plate-like first electrolyte part, formed from a solid electrolyte ceramic and having an electrolyte outer circumferential surface, and a plate-like first surrounding part, formed from an insulating ceramic or a mixture of an insulating ceramic and the solid electrolyte ceramic, and having a through-hole inner circumferential surface forming a through-hole extending in a thickness direction. The first electrolyte part is arranged in the through-hole, and the electrolyte outer circumferential surface of the first electrolyte part is in contact with the through-hole inner circumferential surface of the first surrounding part.The mutually facing contact surfaces of the electrolyte outer circumferential surface of the first electrolyte part and the through-hole inner circumferential surface of the first surrounding part are inclined or chamfered accordingly, such that the positions of the mutually facing contact surfaces move outwards when moving in one direction relative to the thickness direction, and are completely in close contact with each other.

[0008] Since, in the aforementioned gas sensor element, the contact surfaces of the electrolyte outer circumferential surface of the first electrolyte part and the contact surfaces of the through-hole inner circumferential surface of the first surrounding part are inclined such that the positions of the contact surfaces change or migrate outwards when moving to one side with respect to the thickness direction, the contact length along the thickness direction between the contact surface of the first electrolyte part and the contact surface of the first surrounding part can be increased. Furthermore, the contact surfaces of the through-hole inner circumferential surface and the electrolyte outer circumferential surface are in complete and close contact with each other.Thus, the formation of a gap connecting opposing main surfaces of the first electrolyte layer between the electrolyte layer and the first surrounding layer can be avoided, thereby preventing the gas sensor element from being affected by any impairment of accuracy that could otherwise result from gas flow through the gap. Therefore, the gas sensor element can provide high reliability.

[0009] It should be noted that in one mode of the first ceramic composite layer, the entire electrolyte outer circumferential surface of the first electrolyte part and the entire through-hole inner circumferential surface of the first surrounding part can serve as the corresponding contact surfaces. In another mode of the first ceramic composite layer, due to a difference in thickness or arrangement between the first electrolyte part and the first surrounding part, the electrolyte outer circumferential surface of the first electrolyte part or the through-hole inner circumferential surface of the first surrounding part may have a non-contacting surface on one side and / or the other side along the thickness direction with respect to the contact area.

[0010] According to the invention, the electrolyte outer circumferential surface is inclined or beveled such that, in a vertical section of the first electrolyte part along the thickness direction, an angle θ (acute angle (0° to 90°)) between the skin surface on one side of the first electrolyte part and the contact surface (incline) of the electrolyte outer circumferential surface satisfies the relationship 45° ≤ θ ≤ 80° and preferably 55° ≤ θ ≤ 75°. If the angle θ between the skin surface on one side of the first electrolyte part and the contact surface (incline) of the electrolyte outer circumferential surface exceeds 80°, the contact surface is inclined but is almost a vertical surface, which consequently makes it impossible to ensure a sufficient contact length.If the angle θ between the skin surface on one side of the first electrolyte part and the contact area (inclination) of the electrolyte outer circumferential surface is less than 45°, it becomes difficult to maintain a sufficient area of ​​the skin surface on the other side of the first electrolyte part, so that the size of an electrode provided on the skin surface on the other side is reduced, resulting in a reduction of the sensor output signal.

[0011] In addition to an insulating ceramic (e.g., aluminum oxide), a mixture of an insulating ceramic and a solid electrolytic ceramic (e.g., a ceramic mixture of aluminum oxide and zirconium oxide) can be used to form the first surrounding part of the first ceramic composite layer.

[0012] Furthermore, preferably in the manufacture of the aforementioned gas sensor element, the electrolyte part is formed by subjecting an electrolyte layer element, which contains the solid electrolyte ceramic and whose layer element outer circumferential surface is inclined such that the position of the layer element outer circumferential surface moves outwards while moving in one direction with respect to a layer thickness direction, to heat, and the first surrounding part is formed by subjecting to heat a layer of ceramic paste which is in contact with the layer element outer circumferential surface of the electrolyte layer element and contains the insulating ceramic or a mixture of the insulating ceramic and the solid electrolyte ceramic.

[0013] In the manufacture of the aforementioned gas sensor element, the first electrolyte layer is produced by heating the electrolyte layer element, and the first surrounding layer is produced by heating a layer of insulating paste. Prior to heat treatment, the insulating paste layer is in contact with the outer circumferential surface of the electrolyte layer element. Since the heating is thus carried out while maintaining the inclination of the outer circumferential surface of the layer element, a contact surface of the electrolyte outer circumferential surface of the first electrolyte layer can be reliably inclined, as previously mentioned. Furthermore, the insulating paste layer is in direct contact with the outer circumferential surface of the layer element, which becomes the electrolyte outer circumferential surface.Therefore, the gas sensor element can be configured so that the contact surface of the electrolyte outer circumferential surface and the contact surface of the through-hole inner circumferential surface can be in close contact with each other in a reliable manner.

[0014] In addition to an insulating ceramic (e.g., aluminium oxide), a mixture of an insulating ceramic and a solid electrolytic ceramic (e.g., a mixed ceramic of aluminium oxide and zirconium oxide) can also be used to produce the ceramic paste.

[0015] In a further preferred embodiment (3) the aforementioned gas sensor element (1) or (2) further comprises a heating unit which is arranged and configured on one side in relation to the thickness direction in relation to the first ceramic composite layer to heat the first electrolyte part.

[0016] In the gas sensor element (3), the heating unit is arranged on one side relative to the first electrolyte layer, which has the contact surface (incline). This contact surface is inclined such that its position shifts outwards when moving towards one side in the direction of thickness. That is, since the first electrolyte layer, whose cross-sectional area increases towards one side, can be heated by the heating unit from that side relative to the first electrolyte layer, the heating of the first electrolyte layer is facilitated, allowing it to reach a higher temperature and be activated more quickly.

[0017] In a further preferred embodiment (4), the gas sensor element (3) mentioned above comprises a second ceramic composite layer arranged between the first ceramic composite layer and the heating element, and this second ceramic composite layer is configured as follows. The second ceramic composite layer has a plate-like second electrolyte part formed from the solid electrolyte ceramic and having a second electrolyte outer circumferential surface, and has a plate-like second surrounding part formed from the insulating ceramic or a mixture of the insulating ceramic and the solid electrolyte ceramic, with a second through-hole inner circumferential surface forming a second through-hole extending in the thickness direction, and having a higher thermal conductivity than the second electrolyte part.The second electrolyte portion is located in the second through-hole, and its outer electrolyte surface is in contact with the inner through-hole surface of the second surrounding portion. The second electrolyte portion is spaced apart from the first electrolyte portion of the first composite ceramic layer to form a measuring chamber into which the gas to be measured is introduced. The second contact surfaces of the outer electrolyte surface of the second electrolyte portion and the inner through-hole surface of the second surrounding portion, facing each other, are inclined such that their positions move inwards when moving in one direction relative to the thickness, and are in complete and close contact with each other.

[0018] The gas sensor element (4) further comprises a second ceramic composite layer in addition to the first ceramic composite layer. The measuring chamber is formed between the second electrolyte portion of the second ceramic composite layer and the first electrolyte portion of the first ceramic composite layer. The second surrounding portion also has a higher thermal conductivity than the second electrolyte portion. Furthermore, unlike the contact surface of the first ceramic composite layer, the second contact surface of the second ceramic composite layer is inclined such that its position shifts inwards when moving in one direction. That is, in the second composite layer, the second surrounding portion, which has a higher thermal conductivity than the second electrolyte portion, has a larger area on one side (i.e., on the side of the heating element) than on the other side.

[0019] Since in the gas sensor element (4) the second ceramic composite layer is located between the first ceramic composite layer and the heating element, and the measuring chamber is situated between them, it is less likely that heat from the heating element will reach the first electrolyte portion of the first ceramic composite layer compared to the second electrolyte portion of the second ceramic composite layer; therefore, it is less likely that the temperature of the first electrolyte portion of the first ceramic composite layer will increase. However, in this gas sensor element, the second surrounding portion can receive a greater amount of heat generated by the heating element from the surface facing one side, which has a relatively large area of ​​the second surrounding portion with relatively high thermal conductivity, thus enabling the heat to be transferred efficiently to the first ceramic composite layer.In contrast to a case where the second contact surface is parallel to the thickness direction or is inclined in such a way that its position moves outwards when moving towards one side, the first electrolyte part of the first ceramic composite layer can be heated more appropriately and its temperature increased.

[0020] In a second aspect (5) the present invention provides a gas sensor comprising any of the aforementioned gas sensor elements (1) to (4).

[0021] Since the aforementioned gas sensor (5) includes the aforementioned gas sensor element, the gas sensor can provide high reliability by reducing a problem that arises from the formation of a gap between the first electrolyte part and the first surrounding part.

[0022] In a third aspect, the present invention provides a method for manufacturing a gas sensor element comprising a first ceramic composite layer with a plate-like first electrolyte part formed from a solid electrolyte ceramic and having an electrolyte outer circumferential surface, and a plate-like first surrounding part formed from an insulating ceramic or a mixture of an insulating ceramic and the solid electrolyte ceramic and having a through-hole inner circumferential surface forming a through-hole extending in a thickness direction, and wherein the first electrolyte part is arranged in the through-hole.The electrolyte outer circumferential surface of the first electrolyte part is in contact with the through-hole inner circumferential surface of the first surrounding part, and wherein the mutually facing contact surfaces of the electrolyte outer circumferential surface of the first electrolyte part and the through-hole inner circumferential surface of the first surrounding part are each inclined such that the positions of the mutually facing contact surfaces migrate outwards with increasing movement in one direction with respect to the thickness direction, and are in complete close contact with each other. The method comprises a step for producing a composite layer, wherein a green or preliminary ceramic composite layer is formed by placing a layer of ceramic paste containing the insulating ceramic or a mixture of the insulating ceramic and the solid electrolyte ceramic around an electrolyte layer element formed from a thin layer.which contains the solid electrolyte ceramic and has a layer element outer circumferential surface, such that the layer of ceramic paste comes into contact with the layer element outer circumferential surface when drying follows, wherein the layer element outer circumferential surface is inclined such that the position of the layer element outer circumferential surface migrates outwards when moving in one direction with respect to a layer thickness direction; and a step to a heat application to heat the preliminary ceramic composite layer to form the first ceramic composite layer which has the first electrolyte part and the first surrounding part.

[0023] According to the above-mentioned method (6) for manufacturing a gas sensor element, in the step of producing a composite layer, a layer of insulating paste is arranged around the electrolyte layer element in contact with the inclined outer circumferential surface of the layer element. Consequently, the insulating paste layer can be reliably brought into close contact with the outer circumferential surface of the layer element, which has a large contact area. Therefore, a gas sensor element can be manufactured that provides high reliability by preventing the formation of a gap after the application of heat between the contact surfaces of the electrolyte outer circumferential surface of the first electrolyte part and the through-hole inner circumferential surface of the first surrounding part.

[0024] The electrolyte layer element is cut out from an electrolyte layer using a punching tool, or is cut out from the electrolyte layer using an energy beam, such as a laser beam, or a cutting blade.

[0025] According to the invention, the outer circumferential surface of the layer element is inclined or chamfered such that its position changes outwards or migrates outwards when moving in one direction with respect to a layer thickness direction, such that in a vertical section of the electrolyte layer element along the layer thickness direction, an angle θs between the main surface of the electrolyte layer element and the outer circumferential surface of the layer element (incline) satisfies the relationship 45° ≤ θs ≤ 80° and preferably 55° ≤ θs ≤ 75°. If the angle θs between the main surface of the electrolyte layer element and the outer circumferential surface of the layer element exceeds 80°, the outer circumferential surface of the layer element is inclined, but this corresponds almost to a vertical surface, which means that a reliable determination of a sufficient contact length in relation to the surrounding layer of ceramic paste is not achieved.If the angle θs between the skin surface of the electrolyte layer element and the outer circumferential surface of the layer element is less than 45° after heat application, difficulties arise in ensuring a sufficient area of ​​the skin surface on the other side of the first electrolyte part, so that the size of an electrode provided on the skin surface on the other side is reduced, resulting in a reduction of a sensor output signal.

[0026] In a preferred embodiment (7), the aforementioned method for producing a gas sensor element (6) further comprises a cutting step for cutting out, prior to the step for producing a composite layer, the electrolyte layer element from the preliminary layer by directing a cone-shaped converging laser beam from a CW laser onto the preliminary layer and by moving the laser beam in plane directions of the preliminary layer.

[0027] Since the aforementioned method (7) for manufacturing a gas sensor element further includes the cutting step, the electrolyte layer element can be reliably formed whose cut surface (layer element outer circumferential surface) is inclined. Therefore, the gas sensor element can be reliably manufactured by using the electrolyte layer element whose layer element outer circumferential surface is inclined, as previously mentioned. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a longitudinal sectional view of a gas sensor which uses a gas sensor element according to an embodiment or according to a modified embodiment of the present invention. Fig. Figure 2 is a top view of the gas sensor element according to the embodiment or the modified embodiment. Fig. Figure 3 is a perspective elevation view (schematic view) of the gas sensor element according to the embodiment or the modified embodiment. Fig. Figure 4 is an explanatory longitudinal section view showing the structure of the gas sensor element according to the embodiment. Fig. Figure 5A is an explanatory perspective view to illustrate a cutting step in the manufacture of the gas sensor element according to the embodiment. Fig. 5B is an explanatory sectional view to illustrate the cutting step. Fig. Figure 6 is an explanatory view to illustrate a method for manufacturing the gas sensor element according to the embodiment. Fig. Figure 7 is an explanatory view to illustrate a step for producing a composite layer in the manufacture of the gas sensor element according to the embodiment. Fig. Figure 8 is an explanatory view to explain the method for manufacturing the gas sensor element according to the embodiment. Fig. Figure 9 is an explanatory sectional view showing the structure of the gas sensor element according to the modified embodiment. Description of the reference symbols

[0028] Reference symbols used to identify the various features in the drawings include the following: 1,301 Gas sensor 10, 310 Gas sensor element 111 first composite layer (ceramic composite layer) 112 first surrounding part (surrounding parts) 112h through hole 115 Through hole inner circumferential area 115k contact area (of the through-hole inner circumferential surface) 121 first electrolyte part (electrolyte part) 125 Electrolyte outer surface area 125k² contact area (of the electrolyte outer surface area) 131, 331 second composite layer (second ceramic composite layer) 132, 332 second surrounding part 132h, 332h through hole 332s the one surface (of the second surrounding part) (surface of the second surrounding part that faces one side with respect to the thickness direction) 332r the other surface (of the second surrounding part) 135, 335 second through-hole inner circumferential surface 135k, 325k second contact surface (contact area) (of the second through-hole inner circumferential surface) 141, 341 second electrolyte part 145, 345 second electrolyte outer circumferential surface 145k, 345k second contact surface (contact area) (of the second electrolyte outer circumferential surface) 181 Heating unit SP measuring chamber 221 preliminary first composite layer (preliminary ceramic composite layer) 212 insulating paste layer (layer of insulating paste) 221 Electrolyte layer cell 221B Electrolyte layer (preliminary layer) 225 layer element outer perimeter area DT Thickness direction DT1 one side (in relation to the thickness direction) DX first direction (plane direction of the electrolyte layer) DY second direction (plane direction of the electrolyte layer) DZ layer thickness direction DZ1 one side (in relation to the layer thickness direction) LB laser beam DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0029] The present invention is described in more detail below with reference to the drawings. However, the present invention is not limited thereto. (Form of execution)

[0030] First, a gas sensor 1 with a gas sensor element 10 according to an embodiment of the present invention is described. Fig. Figure 1 is a sectional view in the longitudinal direction of the gas sensor 1 according to the embodiment, along an axial line AX. Fig. Figure 2 is a top view of the gas sensor element 10 according to the embodiment. Fig. Figure 3 is a perspective elevation view of the gas sensor element 10. Fig. 4 is an explanatory longitudinal section view corresponding to a section view taken along line B - B. Fig. Figure 2 shows the internal structure of the gas sensor element 10.

[0031] Gas sensor 1 is an oxygen sensor (see Fig. 1), which is attached for use on an exhaust pipe (not shown) of an internal combustion engine. The gas sensor 1 contains the rectangular, plate-like gas sensor element 10 for detecting the oxygen concentration of exhaust gas, which is a gas to be measured, and includes a tubular metallic sleeve 20 to hold the gas sensor element 10. An outer protective element 31 and an inner protective element 32 are located in the front side (in Fig. 1 lower side) of the metallic sleeve 20 arranged with respect to an axial direction DA along the axial line AX, and an outer tube 51 is located on the rear side (in Fig. 1 upper side) with respect to the axial direction DA. The gas sensor 1 further comprises a separator 60, which is arranged and configured in the outer tube 51 to hold the gas sensor element 10, and further comprises five connection elements 75, 75, 76, 76 and 76, which are arranged between the separator 60 and the gas sensor element 10 (see Figure 1). Fig. 1) The five connection elements 75, 75, 76, 76 and 76 are elastically in contact with corresponding supports or connection surfaces 14, 15, 16, 17 and 18, which are to be electrically connected.

[0032] The metallic sleeve 20 holds the gas sensor element 10 in such a way that a front end part 10s of the gas sensor element 10 points forward (in Fig. 1 downwards) protrudes along the axial direction DA, and a rear end part 10k of the gas sensor element 10 extends backwards (in Fig. 1 upwards) protrudes along the axial direction DA. The outer protective element 31 and the inner protective element 32, which are made of metal, cover the front end part 10s of the gas sensor element 10. The outer protective element 31 and the inner protective element 32 each have several holes 31h and 32h, respectively. Through these holes 31h and 32h, gas to be measured can be introduced from outside the outer protective element 31 into a surrounding space around the front end part 10s of the gas sensor element 10, which is located inside the inner protective element 32.

[0033] The outer tube 51 is attached to a rear end portion of the metallic sleeve 20 from the rear side with respect to the axial direction DA. The outer tube 51 holds the separator 60 therein by means of a retaining element 79, and the separator 60 holds the five connection elements 75 and 76, which are provided at the front ends of the five connection leads 74 such that the connection elements 75 and 76 are separated from each other. The separator 60 has an insertion hole 62 extending through it and configured to receive the rear end portion 10k of the gas sensor element 10 (see Fig. 1).

[0034] An opening part at the rear end (opening part at the upper end in Fig. 1) 51c of the outer tube 51 is closed with a feedthrough 73 through which the five connecting lines 74 extend.

[0035] The gas sensor element 10 assumes a rectangular, plate-like shape and is arranged in the gas sensor 1 such that its center line coincides with the axial line AX (see Fig. 1) A longitudinal direction DL of the gas sensor element 10 is parallel to the axial direction DA along the axial line AX, and a front-side DL1 of the longitudinal direction DL corresponds to the aforementioned front side with respect to the axial direction DA, and a back-side DL2 with respect to the longitudinal direction DL corresponds to the aforementioned back side with respect to the axial direction DA.

[0036] The gas sensor element 10 has three sensor connection surfaces 16, 17, and 18, which are formed on a first element main surface 10a, which on the other side DP2 (in Fig. 3 and Fig. 4 upper side) with respect to a thickness direction DT at the rear end part 10k. Furthermore, the gas sensor element 10 has two heating connection surfaces 14 and 15, which are formed on a second main element surface 10b, which faces one side DT1 (in Fig. 3 and Fig. 4 (lower side) with respect to the thickness direction DT at the rear end part 10k. The heating connection surfaces 14 and 15 are electrically connected to a heating unit 181, which will be described later, within the gas sensor element 10. Furthermore, in the gas sensor element 10, the sensor connection surface 16 is electrically connected to a fourth conductor layer 195, which will be described later; the sensor connection surface 17 is electrically connected to a first conductor layer 150, which will be described later; and the sensor connection surface 18 is electrically connected to a second conductor layer 155 and a third conductor layer 190, which will be described below.

[0037] The gas sensor element 10 is composed of several ceramic layers and conductor layers joined together as layers in the thickness direction DT. In particular, as shown in Fig. 3 and Fig. Figure 4 shows a heating layer 180, the fourth conductor layer 195, a second composite layer 131, the third conductor layer 190, an insulating layer 170, the second conductor layer 155, a first composite layer 111, the first conductor layer 150 and a protective layer 160 laminated successively from one side DT1.

[0038] Of these layers, the second composite layer 131 contains a plate-like second surrounding part 132, which is made of an insulating ceramic (aluminum oxide ceramic) and has a through-hole 132h extending in the thickness direction DT and having a rectangular shape when viewed in plan view, and with a plate-like second electrolyte part 141, which is made of zirconium oxide ceramic and is arranged in the through-hole 132h of the second surrounding part 132 (see Fig. 2) The second electrolyte part 141 has an electrolyte part surface 143 facing the other side DT2, and a main electrolyte surface 144 facing one side DT1 (see Fig. 4) The third conductor layer 190, which on the other side is DT2 (in Fig. 4 upper side) of the second composite layer 131 is composed of a rectangular third electrode layer 191, which is arranged on the main electrolyte surface 143 of the second electrolyte part 141 and within the through-hole 132h, and of a ribbon-like third extension layer 192, which extends from the third electrode layer 191 towards the longitudinally rear side DL2 (in Fig. 3 and Fig. 4 right side). The fourth conductor layer 195, which on one side DT1 (in Fig. The fourth electrode layer 196 (located on the lower side of the second composite layer 131 with respect to the thickness direction DT) is composed of a rectangular fourth electrode layer 196, which is located on the electrode skin surface 144 of the second electrolyte part 141 and within the through-hole 132h, and a ribbon-like fourth extension layer 197, which extends from the fourth electrode layer 196 towards the rear side in the longitudinal direction DL2. When using the gas sensor element 10, the fourth electrode layer 196 also serves as a reference oxygen chamber into which oxygen is pumped from a measuring chamber SP, which is described below.

[0039] The first composite layer 111 contains a plate-like first surrounding part 112, which is formed from an insulating ceramic (aluminum oxide ceramic) and has a through-hole 112h extending in the thickness direction DT and having a rectangular shape when viewed on the plane, and contains a plate-like first electrolyte part 121, which is formed from zirconium oxide ceramic and is arranged in the through-hole 112h of the first surrounding part 112 to seal the through-hole 112h airtight (see Fig. 3) The first surrounding part 112 has a through-hole inner circumferential surface 115, which forms the through-hole 112h (see Fig. 4).

[0040] The first electrolyte part 121 has an electrolyte part surface 123 facing the other side DT2, an electrolyte part surface 124 facing one side DT1, and an electrolyte outer circumferential surface 125 in contact with the through-hole inner circumferential surface 115 of the first surrounding part 112 (see Fig. 4).

[0041] A contact surface 115k of the through-hole inner circumferential surface 115 of the first surrounding part 112 and a contact surface 125k of the electrolyte outer circumferential surface 125 of the first electrolyte part 121 are facing each other and are in complete close contact with each other.

[0042] The first conductor layer 150, which is arranged on the other side DT2 of the first interconnection layer 111, is composed of a rectangular first electrode layer 151, which is arranged on the electrolyte skin surface 123 of the first electrolyte part 121 and within the through-hole 112h of the first surrounding part 112, and a ribbon-like first extension layer 152, which extends from the first electrode layer 151 towards the rear side in the longitudinal direction DL2 (in Fig. 3 and Fig. 4 right side) extends.

[0043] The second conductor layer 155, which is arranged on one side DT1 of the first composite layer 111, is composed of a rectangular second electrode layer 156, which is arranged on the electrolyte skin surface 124 of the first electrolyte part 121 and within the through hole 112h, and a ribbon-like second extension layer 157, which extends from the second electrode layer 156 towards the rear side in the longitudinal direction DL2.

[0044] The insulating layer 170 has a rectangular through-hole 170h extending through it and positioned between the through-hole 112h of the first composite layer 111 and the through-hole 132h of the second composite layer 131. The through-hole 170h is surrounded by the first composite layer 111 (first electrolyte part 121) and the second composite layer 131 (second electrolyte part 141) in addition to the insulating layer 170, thus forming the hollow measuring chamber SP (see Fig. 4) is specified. The insulating layer 170 is composed of a body part 171, which is formed from dense aluminum oxide, and two porous parts 172, which are formed from porous ceramic, arranged on respective sides of the through-hole 170h, which extends along the longitudinal direction BL and is exposed towards the outside of the gas sensor element 10 (see Fig. 3) The porous parts 172 are diffusion control layers for introducing gas to be measured into the measuring chamber from outside the gas sensor element 10 at a predetermined flow rate.

[0045] The protective layer 160 is applied to the other side DT2 of the first composite layer 111 and covers the first conductor layer 150. The protective layer 160 consists of a porous part 162, which covers the first electrode layer 151 and the first electrolyte part 121, and a protective part 161, which surrounds the porous part 162 and lies above the first surrounding part 112 to protect the first surrounding part 112 (see Fig. 3).

[0046] As in Fig. As shown in Figure 3, the protective part 161 has three sensor connection surfaces 16, 17, and 18, which are arranged on a first skin surface 160a (the aforementioned first element main surface 10a) and face the other side DT2, oriented longitudinally towards the rear side DL2. The sensor connection surfaces 16 are electrically connected to a rear end part 197e, which is oriented towards the rear side DL2 of the fourth extension layer 197, via through-hole conductors BC formed in through-holes 161m, 112m, 171m, and 132m, extending through the protective layer 160, the first composite layer 111, the insulating layer 170, and the second composite layer 131.The sensor connection surface 17 is electrically connected to a rear end part 152e, which is arranged in the direction of the rear side DL2 of the first extension layer 152, by means of the through-hole conductor BC, which is formed in a through-hole 161n which extends through the protective layer 160 (see . Fig. 3) Furthermore, the sensor connection surface 18 is electrically connected to a rear end part 157e of the second extension layer 157 and a rear end part 192e of the third extension layer 192 by the through-hole conductors BC, which are formed in through-holes 161p, 112p and 171p, which extend through the protective layer 160, the first composite layer 111 and the insulating layer 170 (see Fig. 3).

[0047] The heating layer 180 contains two plate-like insulating layers 182 and 183, which are formed from aluminium oxide and are arranged on one side DT1 with respect to the first composite layer 111, wherein the heating unit 181 is essentially made of Pt and is embedded between the insulating layers 182 and 183 (see Fig. 3 and Fig. 4) The heating unit 181 is composed of a meandering heat-generating part 181d and a first connection part 181b and a second connection part 181c, which are connected to the corresponding opposite ends of the heat-generating part 181d and extend in a straight line. A rear end part 181e of the first connection part 181b is electrically connected to the heating connection surface 14 via the through-hole conductor BC, which is formed in a through-hole 183m extending through the insulating layer 183, and a rear end part 181f of the second connection part 181c is connected to the heating connection surface 15 via the through-hole conductor BC, which is formed in a through-hole 183n extending through the insulating layer 183 (see Fig. 3) electrically connected. When an electrical voltage is applied to the heating unit 181, the first electrolyte part 121 of the first composite layer 111 and the second electrolyte part 141 of the second composite layer 131 are heated and activated, causing the gas sensor element 10 to operate actively.

[0048] In the gas sensor element 10 according to the present embodiment, oxygen is supplied in advance to the fourth electrode layer 196 to form a reference oxygen chamber. Under this condition, the direction and magnitude of the current flowing between the first electrode layer 151 and the second electrode layer 156, between which the first electrolyte part 121 is enclosed, are set such that the first electrolyte part 121 pumps oxygen from the measuring chamber SP to the porous part 162, or pumps oxygen into the measuring chamber SP from the porous part 162 to generate a predetermined potential difference between the third electrode layer 191 and the fourth electrode layer 196, between which the second electrolyte part 141 is enclosed (in order to establish a fixed oxygen concentration in the measuring chamber SP).Since the magnitude of the current flowing between the first electrode layer 151 and the second electrode layer 156 is proportional to the oxygen concentration of the gas to be measured, which flows into the measuring chamber SP via the porous parts 172, the oxygen concentration of the gas to be measured can be determined by the magnitude of the current.

[0049] Meanwhile, the gas sensor element 10 of the present embodiment has the following properties with respect to the first composite layer 111. The mutually facing contact surfaces 115k and 125k of the electrolyte outer circumferential surface 125 of the first electrolyte part 121 and the through-hole inner circumferential surface 115 of the first surrounding part 112 are inclined accordingly towards the outside of the first electrolyte part 121 when moving towards one side DT1 (lower side in Fig. 4) As further explained in Fig. As shown in Figure 4, in the first electrolyte part 121 of the present embodiment, the angle θ between an electrolyte main surface 124, which is arranged in the direction of one side DT1, and the contact surface (incline) 125k of the electrolyte outer circumferential surface 125 is 70°.

[0050] As previously mentioned, the contact surface 115k of the through-hole inner circumferential surface 115 of the first surrounding part 112 and the contact surface 125k of the electrolyte outer circumferential surface 125 of the first electrolyte part 121 face each other and are in complete close contact with each other, with no gap formed between them (see Fig. 3).

[0051] The first electrolyte part 121 is formed by applying heat to an electrolyte layer element 221 (described below), the outer circumferential surface 225 of which (described below) is inclined in a similar manner to the aforementioned electrolyte outer circumferential surface 125. The first surrounding part 112 is produced by applying heat to an insulating paste layer 212 (described below) in wet contact with the outer circumferential surface 225 of the electrolyte layer element 221.

[0052] As previously mentioned, the gas sensor element 10, according to the present embodiment, is designed such that the contact surfaces 125k and 115k of the electrolyte outer circumferential surface 125 and the through-hole inner circumferential surface 115 are inclined towards the outside of the first electrolyte part 121 when moving towards one side DT1. Therefore, the length of the contact in the thickness direction DT between the contact surface 125k of the first electrolyte part 121 and the contact surface 115k of the first surrounding part 112 can be increased. Furthermore, the contact surfaces 115k and 125k of the through-hole inner circumferential surface 115 and the electrode outer circumferential surface 125 are in complete and close contact with each other.Thus, the formation of a connection gap between the opposing main surfaces 123 and 124 of the first electrolyte part 121 and the first surrounding part 112 can be avoided, thereby preventing the gas sensor element 10 from being impaired in accuracy by gas flow through the gap. Therefore, the gas sensor element 10 can be provided with high reliability.

[0053] The first electrolyte part 121 is formed by applying heat to the electrolyte layer element 221, and the first surrounding part 112 is formed by applying heat to the insulating paste layer 212. Furthermore, prior to the application of heat, the insulating paste layer 212 is in contact with the outer circumferential surface 225 of the electrolyte layer element 221. Since the heat treatment is thus carried out while maintaining the inclination of the outer circumferential surface 225 of the layer element, the contact area 125k of the electrolyte outer circumferential surface 125 of the first electrolyte part 121 can be reliably inclined, as previously described. Moreover, the insulating paste layer 212 is in close contact with the outer circumferential surface 225 of the layer element, which is to become the electrolyte outer circumferential surface 125.Therefore, the gas sensor element 10 can be configured such that the contact surfaces 125k and 115k of the electrolyte outer circumferential surface 125 and the through-hole inner circumferential surface 115 of the first surrounding part 112 are completely and reliably in close contact with each other.

[0054] By using the above-mentioned gas sensor element 10, the gas sensor 1 according to the present embodiment can be provided with high reliability by avoiding a problem resulting from the formation of a gap between the first electrolyte part 121 and the first surrounding part 112.

[0055] Furthermore, in this gas sensor element 10, the heating unit 181 is located on one side DT1 (lower side in Fig. 3) arranged with respect to the first electrolyte part 121, which has the contact surface 125k (incline) inclined such that its position moves outwards when moving towards one side DT1. That is, the first electrolyte part 121, whose cross-sectional area increases with increasing movement towards one side DT1, can be heated by the heating unit 181 from that side DT1 with respect to the first electrolyte part 121. Thus, the heating of the first electrolyte part 121 is facilitated, allowing the first electrolyte part 121 to reach temperature and be activated more quickly compared to a case in which the contact surface is inclined in the opposite direction.

[0056] Next, a method for manufacturing the gas sensor element 10 of the gas sensor 1 according to the present embodiment is described with reference to Fig. 5 to 8 described. In the present embodiment, a layer thickness direction DZ designates the thickness direction of the electrolyte layer element 221, etc., which are described below.

[0057] First, a cutting step is performed to cut out the electrolyte layer element 221 with the layer element outer circumferential surface 225, which is inclined in a similar way to the previously mentioned electrolyte outer circumferential surface 125, from an electrolyte layer (provisional or fresh layer) 221B, which is formed from a solid electrolyte ceramic.

[0058] In this cutting step, the electrolyte layer element 221 is cut out of the electrolyte layer 221B using a laser beam LB from a CW laser (in particular a YAG laser). Specifically, the laser beam LB is directed perpendicularly onto a skin surface 221X. Subsequently, the laser beam is moved in a plane direction (for example, a first direction DX or a second direction DY). Fig. 5A) of the electrolyte layer 221B the laser beam LB is continuously emitted.

[0059] Since in the present embodiment the laser beam LB is bundled in a cone shape, as in Fig. As shown in Figure 5B, the cutting surface (layer element outer circumferential surface 225) of the cut-out electrolyte layer element 221 is inclined or chamfered at an angle θs of 70°. When forming a preliminary first composite layer 221 using the electrolyte layer element 221, the electrolyte layer element 221 (which is positioned in reverse) is started from the state of Fig. 5B inverted. In Fig. 5B The skin surface of the electrolyte layer element 221, which faces the other side (upper side), is taken as an electrolyte layer skin surface 223, and the skin surface which faces one side (lower side) and is larger in area than the electrolyte layer skin surface 223 is used as an electrolyte layer skin surface 224.

[0060] Next, a temporary protective layer 260 is produced. The temporary protective layer 260 contains a temporary porous part 262, which is to become the porous part 162 after heat exposure, and a temporary protective part 261, which surrounds the temporary porous part 262 and is to become the protective part 161 after heat exposure. The temporary protective layer 260 has the aforementioned through-holes 161m, 161n, and 161p, located on the rear side DL2 (right side in Fig. 6) of the provisional protective part 261 are provided.

[0061] A preliminary first conductor layer 250 was applied to a main surface of the preliminary protective layer 260 (see Fig. 6) formed. In particular, the preliminary first conductor layer 250 was produced by a known screen printing process such that a preliminary first electrode layer 251 was formed on the preliminary porous part 262 (see Fig. 6) was arranged. Subsequently, an electrolyte paste layer CP, containing a solid electrolyte ceramic, was applied such that it covered the preliminary first electrode layer 251 of the preliminary first conductor layer 250 and the preliminary porous part 262 of the preliminary protective layer 260; the electrolyte layer element 221 was then laminated onto it. The electrolyte paste layer CP contains the same solid electrolyte ceramic as that contained in the electrolyte layer element 221 and is suitable for bonding the electrolyte layer element 221 to the preliminary first electrode layer 251 and the preliminary porous part 262. During the lamination of the electrolyte layer element 221 onto the preliminary porous part 262, etc., the electrolyte layer skin surface 223 of the electrolyte layer element 221 was arranged in the direction of the electrolyte paste layer CP (arranged downwards) (see Fig. 6).

[0062] Subsequently, as in Fig. Figure 7 shows the insulating paste layer 212 arranged around the electrolyte layer element 221 to perform a manufacturing step for a composite layer in order to form a preliminary first composite layer 211.

[0063] In particular, an insulating paste containing an insulating ceramic is applied in such a way that it covers the preliminary protective layer 260 and the preliminary first conductive layer 250 and is in wet contact with the outer circumferential surface 225 of the electrolyte layer element 221, followed by drying to form the insulating paste layer 212 (see Fig. 7) When applying the insulating paste, the insulating paste layer 212 can be reliably brought into close contact with the outer circumferential surface 225 of the layer element with a large contact area, since the liquid insulating paste is in wet contact with the outer circumferential surface 225 of the layer element, which is inclined as mentioned above, and this is also the case after drying.

[0064] In this way, the preliminary first composite layer 211, which is composed of the electrolyte layer element 221 and the insulating paste layer 212, was formed on the preliminary protective layer 260 (see Fig. 7).

[0065] Furthermore, a preliminary second conductor layer 255 was produced on the preliminary first composite layer 211, which is formed on the preliminary protective layer 260. In particular, the preliminary second conductor layer 255 was produced by a screen printing process such that a preliminary second electrode layer 256 is arranged on the electrolyte layer skin surface 224 of the electrolyte layer element 221, and a preliminary second extension layer 257 was formed on the insulating paste layer 212 (see Fig. 8) arranged. In Fig. 8 are the preliminary protective layer 260, the preliminary first composite layer 211, the preliminary second conductor layer 255, etc., compared to the state from Fig. 7 inverted (placed in reverse). Furthermore, it corresponds to in Fig. 8 the vertical direction of the layer thickness direction DZ; one side facing upwards corresponds to the other side DZ2 with respect to the layer thickness direction DZ; and one side facing downwards corresponds to one side DZ1 with respect to the layer thickness direction DZ. In contrast, in Fig. 6 and Fig. 7. One side facing upwards corresponds to one side DZ1 with respect to the layer thickness direction DZ, and one side facing downwards corresponds to the other side DZ2 with respect to the layer thickness direction DZ. Therefore, in the Fig. 6 to 8 the preliminary first composite layer 211 the layer element outer circumferential surface 225, which is inclined towards the outside of the electrolyte layer element 221 when moving towards one side DZ1 with respect to the preliminary first composite layer 211.

[0066] Subsequently, a preliminary second composite layer 231 was formed by a generally known method, such that a rectangular, plate-like preliminary electrolyte part 241, formed on the aforementioned electrolyte layer 221B, was arranged in a layer penetration hole 232h of a preliminary surrounding part 232, which is formed on an insulating preliminary layer (not shown). The preliminary surrounding part 232 is intended to become the second surrounding part 132 after heat treatment, and the preliminary electrolyte part 241 is intended to become the second electrolyte part 141 after heat treatment.

[0067] Subsequently, the through hole 132m was formed in the preliminary surrounding part 232; and then a preliminary third conductor layer 290 and a preliminary fourth conductor layer 295 were screen-printed onto the respective opposing main surfaces of the preliminary second composite layer 231 (see Fig. 8) formed. In particular, the preliminary third conductor layer 290 was formed on a first skin surface 231a, which faces the other side DZ2 of the preliminary second composite layer 231, such that a preliminary third electrode layer 291 thereof was arranged on an electrolyte skin surface 243, which faces the other side DZ2 of the preliminary electrolyte part 241 of the aforementioned preliminary second composite layer 231, and a preliminary third extension layer 292 thereof was arranged on the preliminary surrounding part 232.The preliminary fourth conductor layer 295 was formed on a second skin surface 231b, which faces one side DZ1 of the preliminary second composite layer 231, such that a preliminary fourth electrode layer 296 thereof was arranged on an electrolyte skin surface 244, which faces one side DZ1 of the preliminary electrolyte part 241, and a preliminary fourth extension layer 297 thereof was arranged on the preliminary surrounding part 232.

[0068] Furthermore, the through-holes 183m and 183n are formed in a preliminary insulating layer 283, and the through-holes 171m and 171n are formed in a preliminary body part 271 of a preliminary insulating layer 270. The preliminary insulating layer 270 is further comprised of a rectangular through-hole 270h, formed from the preliminary body part 271, which is to become dense upon exposure to heat, and preliminary porous parts 272, which are to become porous upon exposure to heat. The preliminary porous parts 272 partially form the respective sides of the through-hole 270h, extending along the longitudinal direction DL and exposed laterally (in a direction perpendicular to the longitudinal direction DL and to the layer thickness direction DZ).Meanwhile, the temporary insulating layer 270 (the temporary body part 271 and the temporary porous parts 272) can also be formed by a screen printing process on the temporary first composite layer 211 or the temporary second composite layer 231.

[0069] Then, as in Fig. Figure 8 shows the preliminary insulating layer 283, the preliminary heating unit 281, the preliminary insulating layer 282, the preliminary second composite layer 231, the preliminary insulating layer 270 and the preliminary first composite layer 211, which is coated with the preliminary protective layer 260, laminated successively to form a preliminary element 210.

[0070] Subsequently, temporary through-hole ladders (not shown) are arranged in the corresponding through-holes of the temporary element 210; furthermore, temporary connecting surfaces (not shown) were formed on the temporary element 210 by a screen printing process such that they close the through-holes to the outside of the temporary element 210.

[0071] Subsequently, a heat application step was carried out to apply heat to the preliminary element 210, which contains the preliminary first composite layer 211 (the electrolyte layer element 221 and the insulating paste layer 212).

[0072] The electrolyte layer element 221 is baked out while maintaining the inclination of the layer element's outer circumferential surface 225. In this way, the gas sensor element 10 was produced, which contained the first composite layer 111, composed of the first electrolyte part 121 and the first surrounding part 112 with corresponding inclinations (the mutually facing contact surfaces 125k and 115k of the electrolyte outer circumferential surface 125 and the through-hole inner circumferential surface 115) (see Fig. 2 and Fig. 3).

[0073] According to the method for manufacturing the gas sensor element 10 of the present embodiment, in the composite layer manufacturing step the insulating paste layer 212 is arranged around the electrolyte layer element 221 such that it is in contact with the outer circumferential surface 225 of the layer element, which is inclined in the thickness direction towards the outside of the electrolyte layer element 221, while looking towards one side DZ1 (upwards in Fig. 6 and Fig. 7 or downwards in Fig. 8) in relation to the layer thickness direction of the electrolyte layer 221B. As a result, the insulating paste layer 212 can be reliably brought into direct contact with the outer circumferential surface 225 of the layer element, providing a large contact area. Therefore, the gas sensor element 10, which offers high reliability by preventing the formation, after exposure to heat, of a gap between the contact surfaces 125 and 115k of the electrolyte outer circumferential surface 125 of the first electrolyte part 121 and the through-hole inner circumferential surface 115 of the first surrounding part 112, can be produced.

[0074] Furthermore, in the cutting step, which takes place before the composite layer manufacturing step, the electrolyte layer element 221 can be reliably formed, the cut surface of which (layer element outer circumferential surface 225) is inclined or chamfered, as mentioned previously. Therefore, the gas sensor element 10 can be reliably manufactured using the electrolyte layer element 221, whose layer element outer circumferential surface 225 is inclined, as mentioned previously. (Modified embodiment)

[0075] In the gas sensor 1 of the aforementioned embodiment, as described in Fig. As shown in Figure 4, of the two composite layers 111 and 131, only the first composite layer 111 is designed such that the contact surfaces 115k and 125k of the first electrolyte part 121 and the first surrounding part 112 are inclined so that their positions move outwards when moving towards one side DT1. That is, in the second composite layer 131, the contact surfaces 135k and 145k of the second electrolyte part 141 and the second surrounding part 132 are correspondingly parallel to the thickness direction DT.

[0076] In contrast, in a gas sensor element 310 of a gas sensor 301 according to the present modified embodiment, as in Fig. As shown in Figure 9, not only the first composite layer 111 but also a second composite layer 331 is designed such that the second contact surfaces 335k and 345k of a second electrolyte part 341 and a second surrounding part 332 are inclined accordingly. Furthermore, in contrast to the first composite layer 111, the second contact surfaces 335k and 345k are inclined such that their positions change inwards or move inwards when moving towards one side DT1. Therefore, the present modified embodiment is described, with particular emphasis on features that differ from those of the embodiment. Components similar to those of the embodiment are designated with the same reference numerals, and their descriptions are omitted or abbreviated.

[0077] As previously described, the gas sensor element 310 of the gas sensor 301 of the present modified embodiment is designed such that the heating layer 180, the fourth conductor layer 195, the second composite layer 331, the third conductor layer 190, the insulating layer 170, the second conductor layer 155, the first composite layer 111, the first conductor layer 150, and the protective layer 160 are successively laminated from one side DT1. These layers, with the exception of the second composite layer 331, are designed similarly to those of the gas sensor element 10 of the embodiment.

[0078] Similar to the second composite layer 131 of the embodiment, the second composite layer 331 comprises a plate-like second surrounding part 332, which is formed from an insulating ceramic (aluminum oxide ceramic) and has a through-hole 332h extending in the thickness direction DT and having a rectangular shape when viewed from above, and a plate-like second electrolyte part 341, which is formed from zirconium oxide ceramic and is arranged in the through-hole 332h of the second surrounding part 332 (see Fig. 3) The second electrolyte part 341 is arranged in the through-hole 332h of the second surrounding part 332, and a second electrolyte outer circumferential surface 345 of the second electrolyte part 341 is in contact with a second through-hole inner circumferential surface 325 of the second surrounding part 332. As can easily be seen from Fig. 3 and Fig. As can be seen from Figure 9, the second composite layer 331 is arranged between the first composite layer 111 and the heating unit 181. The first composite layer 111 and the second composite layer 331 are separated from each other by the insulating layer 170. Thus, the second electrolyte part 341 of the second composite layer 131 is spaced apart from the first electrolyte part 121 of the first composite layer 111 to form the measuring chamber SP, into which the gas to be measured is introduced.

[0079] In the first composite layer 111 of the gas sensor element 10, the mutually facing contact surfaces 115k and 125k of the electrolyte outer circumferential surface 125 of the first electrolyte part 121 and the through-hole inner circumferential surface 115 of the first surrounding part 112 are inclined accordingly such that their positions move “outwards” when moving towards one side DT1, and they are completely in close contact with each other.

[0080] In the second composite layer 331, the mutually facing second contact surfaces 335k and 345k of the electrolyte outer circumferential surface 345 of the second electrolyte part 341 and the through-hole inner circumferential surface 335 of the second surrounding part 332 are inclined such that their positions move "inwards" when moving towards one side DT1. That is, in the second composite layer 331, the second surrounding part 332, which has a higher thermal conductivity than the second electrolyte part 341, has a larger area on one side DT1 (i.e., on the side of the heating unit 181) than on the other side DT2 with respect to the thickness direction DT.

[0081] As in Fig. As shown in Figure 9, the angle θ2 (acute angle) between an electrolyte main surface 344, which is arranged in the direction of one side DT1, and the second contact surface (incline) 345k of the electrolyte outer circumferential surface 345 is 70°.

[0082] Aluminum oxide ceramic (thermal conductivity σs = 20 to 30 (W / mK)), used to form the first surrounding part 112 and the second surrounding part 332, has a higher thermal conductivity than zirconia ceramic (thermal conductivity σp = 3 (W / mK)), used to form the first electrolyte part 121 and the second electrolyte part 241. That is, in the second composite layer 331, the second surrounding part 332, with its relatively higher thermal conductivity, has a larger area on one side DT1 (i.e., on the side of the heating element 181) than on the other side DT2.

[0083] In the gas sensor elements 10 and 310 (see Fig. 4 and Fig. 9) In the embodiment and the modified embodiment described above, the second composite layer 131 (331) is located between the first composite layer 111 and the heating unit 181; furthermore, the measuring chamber SP, which is a gap, is also located between them. Thus, it is less likely that heat from the heating unit 181 will reach the first electrolyte part 121 of the first composite layer 111 compared to the second electrolyte part 141 (341) of the second composite layer 131 (331); consequently, it is less likely that the temperature of the first electrolyte part 121 of the first composite layer 111 will rise.

[0084] Therefore, in the gas sensor elements 10 and 310 of the embodiment and the modified embodiment as described above, the contact surfaces 115k and 125k are inclined such that their positions or end positions move “outwards” when moving towards one side DT1, so that more heat is conducted to the first electrolyte part 121.

[0085] Furthermore, in the gas sensor element 310 of the present modified embodiment, the contact surfaces 335k and 345k in the second composite layer 331 are inclined such that their positions or end positions move "inwards" when moving towards one side DT1. As a result, the second surrounding part 332 can absorb a greater amount of heat generated by the heating unit 181 from a surface 332s of it, which faces one side DT1 and has a relatively large area compared to the other surface 332r, which faces the other side DT2, and can effectively transfer the heat from the other surface 332r towards the first composite layer 111 via the insulating layer 170.In comparison to the case in which the second contact surfaces 135k and 145k are parallel to the thickness direction, as in the case of the embodiments described above, or when they are inclined in such a way that their positions move “outwards” when moving towards one side DT1, the first electrolyte part 121 of the first composite layer 111 can be heated and its temperature increased more appropriately.

[0086] Since the second electrolyte part 341 is located near the heating element 181, the second electrolyte part 341 can be easily heated and its temperature increased.

[0087] The second contact surface 335k of the second through-hole inner circumferential surface 325 of the second surrounding part 332 and the second contact surface 345k of the second electrolyte outer circumferential surface 345 of the second electrolyte part 341 are facing each other and inclined and are in complete close contact with each other, without a gap being formed between them (see Fig. 3) Thus, the gas sensor 301 can offer high reliability, as the problem arising from the formation of a gap between the second electrolyte part 341 and the second surrounding part 332 is avoided.

[0088] Since the second composite layer 331 can be produced by a process similar to that used to produce the first composite layer 111 in the embodiment, the process will only be briefly described below. First, an electrolyte layer (provisional layer) formed from a solid electrolyte ceramic is irradiated with the cone-shaped laser beam LB to cut out a second electrolyte layer element whose cut surface is beveled or inclined at an angle θs of 70°. Subsequently, an insulating paste containing an insulating ceramic is applied around the second electrolyte layer element so that it is in wet contact with the outer circumferential surface of the second electrolyte layer element, followed by drying to form the insulating paste layer (see Fig.7) By using such an application of the insulating paste, even after drying the insulating paste layer can be reliably brought into close contact with the outer circumferential surface of the electrolyte layer element with a large contact area, since the liquid insulating paste is in wet contact with the outer circumferential surface 225 of the layer element, which is inclined or beveled as described above.

[0089] Although the present invention is described with reference to the embodiment and the modified embodiment, the present invention is not limited to these, but can be modified in a suitable manner without deviating from the basic idea of ​​the invention.

[0090] In the gas sensor element 10 of the embodiments described above, of the two ceramic composite layers (the first composite layer 111 and the second composite layer 131), the first composite layer 111 is designed such that the contact surface 125k of the electrolyte outer circumferential surface 1252 is inclined such that its position moves “outwards” when moving in the direction of one side DT1. In the modified embodiment, of the two ceramic composite layers (the first composite layer 111 and the second composite layer 331), the first composite layer 111 is designed such that the contact surface 125k of the electrolyte outer circumferential surface 125 is chamfered so that its position moves “outwards” when moving towards one side DT1, and the second composite layer 331 is designed such that the second contact surface 345k of the second electrolyte outer circumferential surface 345 is chamfered so that its position moves “inwards” when moving towards one side DT1.

[0091] However, the gas sensor element can have the following structural feature: the first and second composite layers are designed such that the outer electrolyte surface and the second electrolyte surface are angled so that their positions move "outwards" when moving to one side, or so that their positions move "inwards" when moving to one side. According to this sensor element, the contact length along the thickness direction between the contact surfaces of the electrolyte parts (the first electrolyte part and the second electrolyte part) and the contact surfaces of the surrounding parts (the first surrounding part and the second surrounding part) can be increased.Furthermore, since the contact surfaces of the through-hole inner circumferential surface and the electrolyte outer circumferential surface are completely in close contact with each other, the formation of connection gaps between the opposing main surfaces of the electrolyte parts and between the electrolyte parts and the surrounding parts can be prevented.

[0092] In the embodiment and the modified embodiment described above, the present invention is applied to the gas sensor element having two ceramic composite layers; however, the present invention can also be applied to a gas sensor element having a single ceramic composite layer or to a gas sensor element having three ceramic composite layers. In the case that the gas sensor element has three ceramic composite layers, at least one ceramic composite layer is designed such that its electrolyte portion is chamfered, as previously described.

[0093] Furthermore, in the embodiment and the modified embodiment described above, an insulating ceramic (aluminum oxide ceramic) is used to form the first and second surrounding parts of the first and second composite layers; however, a mixed ceramic of aluminum oxide and zirconium oxide can be used.

[0094] Furthermore, in the embodiment described above, the first electrolyte part (electrolyte part) 121 and the first surrounding part (surrounding part) 112, which form the first composite layer (ceramic composite layer) 111, have the same thickness; the entire outer electrolyte circumferential surface 125 of the first electrolyte part 121 serves as the contact surface 125k; and the entire inner circumferential surface 115 of the first surrounding part 112 serves as the contact surface 115k. However, the following possibility also exists: due to a difference in thickness between the electrolyte part and the surrounding part, or a difference in position along the thickness direction between the electrolyte part and the surrounding part, a portion of the outer electrolyte circumferential surface serves as a contact surface, and a portion of the inner circumferential surface of the through-hole serves as a contact surface.

[0095] The invention is described in detail with reference to the preceding embodiments. However, the invention should not be considered limited thereto. Furthermore, it should be clear to those skilled in the art that various modifications to the form and detail of the invention as shown and described are possible. It is intended that such modifications are included in the basic concept and scope of the appended claims.

Claims

[1] A gas sensor element (10, 310) comprising a first ceramic composite layer (111) with a plate-like first electrolyte part (121) formed from a solid electrolyte ceramic and having an electrolyte outer circumferential surface (125), and a plate-like first surrounding part (112) formed from an insulating ceramic or a mixture of an insulating ceramic and the solid electrolyte ceramic and having a through-hole inner circumferential surface (115) forming a through-hole (112h) extending in a thickness direction (DT), wherein the electrolyte part (121) is arranged in the through-hole (112h) and the electrolyte outer circumferential surface (125) of the first electrolyte part (121) is in contact with the through-hole inner circumferential surface (115) of the first surrounding part (112), wherein mutually facing contact surfaces (115k, 125k) of the electrolyte outer circumferential surface (125) of the first electrolyte part (121) and the through-hole inner circumferential surface (115) of the first surrounding part (112) are inclined accordingly towards the outside of the first electrolyte part (121), while moving to one side (DT1) with respect to the thickness direction (DT) and are completely in close contact with each other, and in a vertical cross-section along the thickness direction (DT) of the electrolyte part (121) a main surface (124) of the electrolyte part (121) and the contact surface (125k) of the electrolyte outer circumferential surface (125) form an angle (θ) which is equal to or greater than 45° but equal to or less than 80° (45° ≤ θ ≤ 80°). [2] Gas sensor element (10, 310) according to claim 1, wherein the electrolyte part (121) is formed by applying heat to an electrolyte layer element (221) which contains the solid electrolyte ceramic and whose outer circumferential surface (225) of the layer element is inclined towards the outside of the layer element as it moves towards one side (DZ1) with respect to a layer thickness direction (DZ), and the first surrounding part (112) is formed by applying heat to a layer of ceramic paste which is in contact with the outer circumferential surface (225) of the electrolyte layer element (221) and contains the insulating ceramic or a mixture of the insulating ceramic and the solid electrolyte ceramic. [3] Gas sensor element (10, 310) according to claim 1 or 2, which further comprises a heating unit (181) which is arranged and configured on one side (DT1) with respect to the thickness direction (DT) in relation to the first ceramic composite layer (111) to heat the first electrolyte part (121). [4] Gas sensor element (310) according to claim 3, which further comprises a second ceramic composite layer arranged between the first ceramic composite layer (111) and the heating unit (181), wherein The second ceramic composite layer has a plate-like second electrolyte part (341) formed from the solid electrolyte ceramic and containing a second electrolyte outer circumferential surface (345), and a plate-like second surrounding part (332) formed from the insulating ceramic or a mixture of the insulating ceramic and the solid electrolyte ceramic, with a second through-hole inner circumferential surface (335) forming a second through-hole (332h) extending in the thickness direction (DT) of the gas sensor element (310), and having a thermal conductivity greater than that of the second electrolyte part (341), wherein the second electrolyte part (341) is arranged in the second through-hole (332h), and the second electrolyte outer circumferential surface (345) of the second electrolyte part (341) is in contact with the second through-hole inner circumferential surface (335) of the second surrounding part. (332) is; the second electrolyte part (341) is arranged at a distance from the first electrolyte part (121) of the first ceramic composite layer (111) to form a measuring chamber (SP), into which the gas to be measured is to be introduced; and The second contact surfaces (335k, 345k) of the second electrolyte outer circumferential surface (345) of the second electrolyte part (341) and the second through-hole inner circumferential surface (335) of the second surrounding part (332) facing each other are inclined accordingly towards the interior of the second electrolyte part (341), while moving to one side (DT1) with respect to the thickness direction (DT) and are completely in close contact with each other. [5] Gas sensor (1, 301) with a gas sensor element (10, 310) according to one of claims 1 to 4. [6] A method for producing a gas sensor element (10, 310) comprising a first ceramic composite layer (111) with a plate-like first electrolyte part (121) formed from a solid electrolyte ceramic and containing an electrolyte outer circumferential surface (125), and with a plate-like first surrounding part (112) formed from insulating ceramic or a mixture of an insulating ceramic and the solid electrolyte ceramic and containing a through-hole inner circumferential surface (115) forming a through-hole (112h) extending in a thickness direction (DT) of the gas sensor element, wherein the first electrolyte part (121) is arranged in the through-hole (112h), the electrolyte outer circumferential surface (125) of the electrolyte part (121) is in contact with the through-hole inner circumferential surface (115) of the first surrounding part (112), and each other facing contact surfaces (115k,125k) of the electrolyte outer circumferential surface (125) of the first electrolyte part (121) and the through-hole inner circumferential surface (115) of the surrounding part (112) are inclined accordingly towards the outside of the first electrolyte part (121), while moving towards one side (DT1) with respect to the thickness direction (DT) and are completely in close contact with each other, in a vertical cross-section along the thickness direction (DT) of the electrolyte part (121) a main surface (124) of the electrolyte part (121) and the contact surface (125k) of the electrolyte outer circumferential surface (125) form an angle (θ) which is equal to or greater than 45° but equal to or less than 80° (45° ≤ θ ≤ 80°) the procedure includes: a composite layer manufacturing step for forming a preliminary ceramic composite layer (211) by arranging a layer (212) of ceramic paste containing the insulating ceramic or a mixture of the insulating ceramic and the solid electrolyte ceramic around an electrolyte layer element (221) formed from a preliminary layer (221B) containing the solid electrolyte ceramic and having a layer element outer circumferential surface (225), such that the ceramic paste layer (212) comes into contact with the layer element outer circumferential surface (225), followed by drying, wherein the layer element outer circumferential surface (225) is inclined towards the outside of a layer element as it moves towards one side (DZ1) with respect to a layer thickness direction (DZ); and a heat application step to apply heat to the preliminary ceramic composite layer (211) in order to form the first ceramic composite layer (111) with the first electrolyte part (121) and the first surrounding part (112); and in a vertical cross-section along the thickness direction (DT) of the electrolyte part (221) a main surface (224) of the electrolyte part (221) and the contact surface (225k) of the electrolyte outer circumferential surface (225) form an angle (θs) which is equal to or greater than 45° but equal to or less than 80° (45° ≤ 0 ≤ 80°). [7] Method for producing a gas sensor element (10, 310) according to claim 6, further comprising a cutting step to cut out the electrolyte layer element (221) from the preliminary layer (221B) prior to the composite layer manufacturing step by directing a cone-shaped laser beam (LB) from a CW laser onto the preliminary layer (221B) and moving the laser beam (LB) in a plane direction (DX, DY) of the preliminary layer (221B).

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