Gas sensor

Abstract

Gas sensor that includes: a substantially cylindrical metal sleeve (2); a laminated sensor element (10) which is received in the metal sleeve (2), wherein the sensor element (10) contains: a plate-shaped continuous electrolyte layer (201) extending in a longitudinal direction; an electrode section (204) laminated onto the continuous electrolyte layer (201); and a lead section (205) which is connected to the electrode section (204), and extends in the longitudinal direction, wherein the sensor element includes an insulating layer (202) laminated onto the continuous electrolyte layer (201); and the lead-in section includes a front end section (205a) laminated onto the continuous electrolyte layer (201), as well as having a rear end section (205b) which is laminated over the insulating layer (202) onto the electrolyte layer (201), and wherein the insulating layer (202) has an end section (212) over which and transversely to which the supply section (205) extends and which, viewed in the lamination direction, has a recessed shape, a raised shape or a recessed and raised shape in the longitudinal direction.

Description

Background of the invention

[0001] The present invention relates to a gas sensor configured to detect the concentration of a specific gas component in a sample gas to be tested.

[0002] It is a conventional gas sensor employing a laminated sensor element, known as a gas sensor configured to detect the concentration of a specific gas component in exhaust gas emitted by a vehicle's internal combustion engine, etc., in order to control the combustion process of the internal combustion engine. The laminated sensor element includes, for example, an element body and a heating device configured to activate the base body by heating it.

[0003] US patent application US2003-159928 A1 (corresponding to Japanese patent application JP 2003-322632 A) discloses a gas sensor comprising a base body with a cell and a heating element. The cell has a continuous electrolyte layer, consisting mainly of, for example, zirconium oxide, a pair of electrode sections, consisting mainly of platinum and formed on both main surfaces of the continuous electrolyte layer, and a pair of lead sections, consisting mainly of platinum and connected to the paired electrode sections, each of the paired lead sections extending along the continuous electrolyte layer.The heating device comprises a pair of base layers, consisting, for example, mainly of aluminium oxide, a heating section consisting mainly of platinum and enclosed between the pair of base layers, and a pair of heating device supply sections, consisting mainly of platinum and connected to both end sections of the heating section, each of the pair of heating device supply sections extending along an insulating layer.

[0004] Another sensor is described in US 2005 / 0189222 A1. The corresponding electrodes are separated by a ceramic green material. This green material has one section that serves as the electrolyte and is made, for example, of zirconia, and another section that serves as the insulation section and is made, for example, of aluminum oxide. A beveled edge is provided between the two sections. Summary of the invention

[0005] In particular, a gas sensor with the features of claim 1 is specified. Further advantageous embodiments are defined in the dependent claims.

[0006] Each of the lead sections, except for a section at the front end that is connected to the electron section, extends across the insulating layer of the continuous electrolyte layer to accurately measure the concentration by suppressing catalytic reaction (catalysis). That is, the lead section is designed to extend across an end section of the insulating layer and perpendicular to it. However, during manufacturing, cracks develop in a section of the lead section that extend across the end section of the insulating layer and perpendicular to it. This may prevent the output signal from the electrode sections from being received.

[0007] In the sensor element, an unfired continuous electrolyte plate 901 is formed, which after firing becomes the continuous electrolyte layer, as described in Fig. Figure 9A shows the process. An insulating paste is printed onto the continuous electrolyte plate 901 to form an insulating pattern 902, which becomes the insulating layer after firing. A conductive paste is applied using screen printing to form a lead pattern 905, which becomes the lead section after firing. The entire assembly is then dried and fired to form the sensor element.

[0008] In this case, a surface of the insulating pattern 902 is one step higher than a surface of the continuous electrolyte plate 901. Therefore, the conductive paste is not sufficiently printed onto an end section 912 of the insulating pattern 902, particularly at a corner section of the end section 912 of the insulating pattern 902. In this corner section of the end section 912 of the insulating pattern 902, the lead-in pattern is thin. The tensile stress, in response to contraction of the lead-in pattern 905 during drying or firing, is concentrated on the thin section (transverse section m extending over and perpendicular to the insulating pattern 902). This is how the crack forms.

[0009] One object of the present invention is therefore to create a gas sensor with which the problem described above is to be solved, namely to prevent the formation of a crack in a supply line section which extends over an insulating layer and across it, and to accurately measure a concentration.

[0010] According to one aspect of the present invention, a gas sensor comprises a substantially cylindrical metal sleeve and a laminated sensor element received in the metal sleeve, the sensor element comprising a plate-shaped continuous electrode layer extending longitudinally, an electrode section laminated onto the continuous electrolyte layer, and a lead section connected to the electrode section and extending longitudinally. The sensor element includes an insulating layer laminated onto the continuous electrode layer, and the lead section has a front end section laminated directly onto the continuous electrolyte layer and a rear end section laminated over the insulating layer onto the continuous electrolyte layer.The insulating layer has an end section over which and across which the supply section extends and which, viewed in the lamination direction, has a recessed shape, a raised shape or a recessed and raised shape in the longitudinal direction. Brief description of the drawings Fig. Figure 1 is a sectional view showing a gas sensor according to a first embodiment of the present invention. Fig. Figure 2 is an expanded perspective view showing a basic structure of a sensor element used in the gas sensor according to the first embodiment of the present invention. Fig. Figure 3A is a top view showing an example in which an end section of an insulating layer in the gas sensor according to the first embodiment of the present invention has a recessed shape. Fig. 3B is a section view along a section line IIIB-IIIB. Fig. Figure 4 is a top view showing an example in which an end section of an insulating layer in a gas sensor according to a second embodiment of the present invention has a raised shape. Fig. Figure 5 is a top view showing an example in which an end section of an insulating layer in a gas sensor according to a third embodiment of the present invention has a recessed and raised shape. Fig. Figure 6A is a top view showing an example in which an end section of a first supply line section in a gas sensor according to a fourth embodiment of the present invention has a recessed shape. Fig. 6B is a section view along a section line VIB-VIB in Fig. 6A. Fig. Figure 7 is a top view showing an example in which an end section of a first supply line section in a gas sensor according to a fifth embodiment of the present invention has a raised shape. Fig. Figure 8 is a top view showing an example in which an end section of a first supply line section in a gas sensor according to a sixth embodiment of the present invention has a recessed and raised shape. Fig. Figure 9A is a top view showing an example of a conventional sensor element. Fig. 9B is a section view along a section line IXB-IXB. Detailed description of the invention

[0011] The following describes gas sensors according to various embodiments with reference to the drawings. Fig. Figure 1 is a sectional view showing a gas sensor according to a first embodiment of the present invention. The term "front" refers to a gas detection side with respect to an axial direction of a gas sensor, and the term "rear" refers to a side opposite the front. This gas sensor 1 is a wide-range (or full-range) air-fuel ratio sensor used for controlling the air-fuel ratio of internal combustion engines and vehicles, and is installed in the exhaust lines of these internal combustion engines and vehicles.

[0012] The gas sensor 1 comprises a plate-shaped sensor element 10 extending axially and configured to detect a specific gas in an exhaust gas, which is the gas to be measured, and a cylindrical metal sleeve 11 that houses the sensor element 10 and is attached to the exhaust pipe. The sensor element 10 is held in place by both end sections (a front end section on a lower side of the Fig. 1 and a rear end section on an upper side in Fig. 1) protrudes from the metal sleeve 11. A porous protective layer 10a of the front end is formed on a front end section of the sensor element 10, which is a detection section, and which protrudes beyond the front end section of the metal sleeve 11.

[0013] The metal sleeve 11 includes a screw section 11a, which is located radially outside the metal sleeve 11 and is designed to fasten the metal sleeve 11 to the exhaust pipe, and a base section 11b, which is located radially inside the metal sleeve 11 and which is a chamfered surface having an inclination with respect to a plane perpendicular to the axial direction.

[0014] The gas sensor 1 comprises an annular ceramic holder 12, powder-filled layers (hereinafter referred to as talc rings 13 and 14), and a ceramic bushing 15, arranged in this order from the front end (bottom side in Fig. 1) here to the back side (top side in Fig. 1) are arranged in the metal sleeve 11 and surround an outer circumferential section of the sensor element 10. The gas sensor 1 includes a metal holder 16, which is arranged radially outside the ceramic holder 12 and the talc ring 13 and is configured to ensure the airtightness of the metal sleeve 11. Furthermore, the gas sensor 1 includes a compressed seal 17, which is arranged at a rear end section of the ceramic bushing 15. A rear end section of the metal sleeve 11 is compressed such that the ceramic bushing 15 is pushed towards the front end over the compression seal 17.

[0015] The gas sensor 1 includes a pair of protective devices (an outer protective device 21 and an inner protective device 22) which are attached to the front end section of the metal sleeve 11 by welding, etc., and which are made of metal, such as stainless steel, have a multitude of holes, and surround the front end section of the sensor element 10. Furthermore, the gas sensor 1 includes an outer cylinder 26, which is attached to the rear end section of the metal sleeve 11 and surrounds the sensor element 10. The gas sensor 1 also includes connecting terminals 27 and five connecting wires (in Fig. 1 three wires are shown), 28, each having a front end section electrically connected to one of the connection terminals 27, and a rear end section electrically connected to external devices, a through-seal 29, which is attached to an opening section of the outer cylinder 26 at its rear end (top side in Fig. 1) is arranged and is provided with supply wire holes 29a through which the supply wires 28 pass.

[0016] Within the outer cylinder 26 is an insulating contact element 31 that electrically connects the electrode connection sections 41 and heating element connection sections 42 of the sensor element 10, as well as the connecting terminals 27. The insulating contact element 31 has a cylindrical shape with a contact through-hole 31a extending axially through it. The sensor element 10 and the connecting terminals 27 are inserted into the contact through-hole 31a of the insulating contact element 31. The connecting terminals 27 are pressed against the electrode connection sections 41 and the heating element connection sections 42 of the sensor element 10, thus electrically connecting the connecting terminals 27 to the electrode connection sections 41 and the heating element connection sections 42.These components form current paths between the electrode connection sections 41 and the heating device connection sections 42 of the sensor element 10 and the external devices.

[0017] The insulating contact element 31 includes a flanged section or projecting section 31b that extends radially outwards from the insulating contact element 31. The gas sensor 1 includes a retaining element 32 located inside the outer cylinder 26. The flanged section 31b of the insulating contact element 31 is supported by the retaining element 32 such that the insulating contact element 31 is held within the outer cylinder 26.

[0018] Fig. Figure 2 is an expanded perspective view showing a sensor element 10 (except for the protective layer 10a of the front end) that is used in the gas sensor according to the embodiments of the present invention. Fig. Figure 2 shows a basic structure in which a sensor lead section is formed over an insulating layer on a continuous electrolyte layer. Fig. 2 The insulating layer has a flat end section as in the conventional gas sensor, and both the sensor lead section and the heating element lead section have a continuous, undivided shape. However, in the sensor element 10 according to the embodiments of the present invention, these components are modified as desired, as described below.

[0019] The sensor element 10 contains a base body 100 with an oxygen concentration detection cell 110, an intermediate regulating layer 120 and an oxygen pump cell 130, which are laminated in this order, as well as a heating device 130 which is set up to heat the base body 100.

[0020] The oxygen concentration detection cell 110 contains a first continuous electrolyte layer 114 with a first main surface located on a lower side in Fig. 2, as well as a second main surface located on an upper side of Fig. 1. The oxygen concentration detection cell 110 contains a first insulating layer 114, a first electrode section 112 and a first sensor lead section 113, which are formed on the first main surface of the first continuous electrolyte layer 115, as well as a second insulating layer 116, a second electrode section 118 and a second sensor lead section 119, which are formed on the second main surface of the first continuous electrolyte layer 115.

[0021] The first electrode section 112 has a substantially rectangular shape. The first electrode layer 112 is connected to the first continuous electrolyte layer 115 at the front end (the left side of the Fig. 2) of the first insulating layer 114. The first sensor lead section 113 is connected to a rear end (the right side of Fig. 2) of the first electrode section 112. The first sensor lead section 113 extends longitudinally along the first continuous electrolyte layer 115. The first sensor lead section 113 has a front end section (on the left side of Fig. 2), which is formed directly on the first continuous electrolyte layer 115, as well as a rear end section (on the right side of Fig. 2), which is formed over the first insulating layer 114 on the first continuous electrolyte layer 115.

[0022] The rear end section (on the right side of Fig. 2) of the first sensor lead section 113 is electrically connected to one of the electrode connection sections 41 via a first through hole 114a formed in the first insulating layer 114, a second through hole 115a formed in the first continuous electrolyte layer 115, a third through hole 120a formed in the intermediate regulating layer 120, a sixth through hole 135a formed in a second continuous electrolyte layer 135, and an eighth through hole 140a formed in a surface protection layer 140.

[0023] The second electrode section 118 has an essentially rectangular shape. The second electrode section 118 is attached to the first continuous electrolyte layer 115 at the front end (the left side of the Fig. 2) of the second insulating layer 116. The second sensor lead section 119 extends in the longitudinal direction of the first continuous electrolyte layer 115. This second sensor lead section 119 has a front end section (on the left side of Fig. 2), which is formed directly on the first continuous electrolyte layer 115, and a rear end section (on the right side of Fig. 2), which is formed over the second insulating layer 116 on the first continuous electrolyte layer 115.

[0024] The rear end section (on the right side of Fig. 2) of the sensor lead section 119 is electrically connected to one of the electrode connection sections 41 via a fourth through hole 120b formed in the intermediate layer regulating layer 120, a fifth through hole 134a formed in the third insulating layer 134, a seventh through hole 135b formed in the second continuous electrolyte layer 135, and a ninth through hole 140b formed in the surface protection layer 140.

[0025] Furthermore, the oxygen pump cell 130 contains the second continuous electrolyte layer 135, which forms a first main surface located on the lower side in Fig. 2, and has a second main surface located on the upper side in Fig. 2. The oxygen pump cell 130 contains a third insulating layer 134, a third electrode section 132 and a third sensor lead section 133, which is formed on the first main surface of the second continuous electrolyte layer 135, and a fourth insulating layer 136, a fourth electrode section 138 and a fourth sensor lead section 139, which is formed on the second main surface of the second continuous electrolyte layer 135.

[0026] The third electrode section 132 has an essentially rectangular shape. The third electrode section 132 is attached to the second electrolyte layer 135 at the front end (the left side of the Fig. 2) the second insulating layer 134. The third sensor lead section 133 is formed with a rear end (on the right side of Fig. 2) of the third electrode section 132. The third sensor lead section 133 extends longitudinally along the second continuous electrolyte layer 135. This third sensor lead section 133 has a front end section (on the left side in Fig. 2) on, which is formed directly on the second continuous electrolyte layer 135, as well as a rear end section (on the right side of Fig. 2), which is formed via the fourth insulating layer 136 on the second continuous electrolyte layer 135.

[0027] The rear end section (on the right side of Fig. 2) The third sensor lead section 133 is electrically connected to one of the electrode sections 41 via the fifth through-hole 134a, which is formed in the third insulating layer 134, the seventh through-hole 135b, which is formed in the second continuous electrolyte layer 135, and the ninth through-hole 140b, which is formed in the surface protection layer 140. The sensor lead section 119 has the same potential as the third sensor lead section 133 via the fourth through-hole 120b.

[0028] The fourth electrode section 138 has a substantially rectangular shape. The fourth electrode section 138 is attached to the second continuous electrolyte layer 135 at the front end (the left side of the Fig. 2) of the fourth insulating layer 136. The fourth sensor lead section 139 is formed with a rear end (on the right side of Fig. 2) of the fourth electrode section 138. The fourth sensor lead section 139 extends in the longitudinal direction of the second continuous electrolyte layer 135. This fourth sensor lead section 139 contains a front end section (on the left side of Fig. 2), which is formed directly on the second continuous electrolyte layer 135, and a rear end section (on the right side in Fig. 2), which is formed over the fourth insulating layer 136 on the second continuous electrolyte layer 135. The rear end section (on the right side in Fig. 2) is electrically connected to one of the connection sections 41 via a tenth through hole 140c formed in the surface protection layer 140.

[0029] The intermediate regulating layer 120, located between the oxygen concentration sensing cell 110 and the oxygen pump cell 130, contains a sensing chamber 120c, which is an empty space enclosed between the second electrode section 118 and the third electrode section 132. The intermediate regulating layer 120 includes diffusion control sections 121, arranged on both sides of the sensing chamber 120c in a lateral direction. These sections are configured to control the sample gas at a constant velocity, independent of any flow velocity outside the element, and to guide the sample gas. The diffusion control sections 121 are porous to facilitate the guidance of the sample gas.

[0030] The surface protection layer 140 is laminated onto the second continuous electrolyte layer 135 to enclose the fourth electrode section 138 and the fourth sensor lead section 139. The surface protection layer 140 includes a through-hole 140d located at the point where it overlaps with the fourth electrode section 138. An electrode protection section 141 is fitted into the through-hole 140d of the surface protection layer 140.

[0031] The heating device, on the other hand, comprises a first base layer 161 and a second base layer 167, consisting mainly of aluminum oxide, a heating section 163, consisting mainly of platinum and enclosed between the first base layer 161 and the second base layer 167, and a pair of heating device supply sections 164, each extending from the heating section 163 in a longitudinal direction along the first base layer 161, etc. The rear ends (on the right side in Fig. 2) The heating device supply line sections 164 are each connected to the heating device connection sections 42 via through holes formed in the first base layer 161.

[0032] In the following, the first continuous electrolyte layer 115 and the second continuous electrolyte layer 135 are referred to as a continuous electrolyte layer 201. The first insulating layer 114, the second insulating layer 116, the third insulating layer 134, and the fourth insulating layer 136 are referred to as an insulating layer 202. The first electrode section 112, the second electrode section 118, the third electrode section 132, and the fourth electrode section 138 are referred to as an electrode section 204. The first sensor lead section 113, the second sensor lead section 119, the third sensor lead section 133, and the fourth sensor lead section 139 are referred to as a lead section 205.

[0033] Fig. Figure 3A is a top view showing an insulating layer 202 of a gas sensor 1 according to a first embodiment of the present invention. Fig. 3B is a sectional view along a section line IIIB-IIIB in Fig. 3A. In Fig. In Figures 3-9, a left side of each drawing is a front end, and a right side of each drawing is a rear end. In this embodiment, an end section 212 of the insulating layer 202 has a recessed or concave shape which, viewed in the lamination direction, is recessed or concave in the longitudinal direction. The insulating layer 202 is, as shown in Fig. 3A and Fig. 3B, formed on the continuous electrolyte layer 201. The insulating layer 202 includes the end section 212 at the front end, which has a recessed shape. The supply section 205 includes a front end section 205a, which is formed directly on the continuous electrolyte layer 201, and a rear end section 205b, which is formed over the insulating layer 202 on the continuous electrolyte layer 201. That is, the insulating layer 202 is formed between the rear end section 205b of the supply section 205 and the continuous electrolyte layer 201, as shown in Fig. 3B is shown.

[0034] The conductive paste can be printed onto the insulating layer 202 thus formed, with the recessed end section 212, in such a way that it gradually forms a corner section of the end section 212 of the insulating pattern 202 from both sides of the end section 212 of the insulating pattern 202 in the lateral directions (upwards and downwards). Fig. 3A) increases when the conductive paste is printed from the front end to the back end during manufacturing. Conversely, the conductive paste can be printed such that it slopes down in the width direction from a central section of the end section 212 of the insulating pattern 202 to the corner section of the end section 212 of the insulating layer 202 when the conductive paste is printed in the opposite direction (from the back end to the front end). Accordingly, in both cases, it is possible to increase the thickness of a transverse section m of the lead pattern 205, which extends over and across the end section 212 of the insulating pattern 202, relative to the thickness of the conventional gas sensor. Furthermore, the lead section 205 can gradually extend over and across the end section 212 of the insulating pattern 202.Therefore, it is possible to prevent the formation of cracks in the supply pattern 205, which extends over the end section 212 of the insulating pattern 202 and across it, even if the supply pattern 205 contracts during drying and firing.

[0035] Fig. Figure 4 is a top view showing an insulating layer 202 of a gas sensor 101 according to a second embodiment of the present invention. In this embodiment, the end section 212 of the insulating layer has a raised or convex shape which, viewed in the lamination direction, is raised or convex in the longitudinal direction. The conductive paste can be printed onto the insulating layer 202 thus formed with the raised end section 212 in such a way that it gradually rises in the lateral direction from the central section of the end section 212 of the insulating layer 202 towards the corner section of the end section 212 of the insulating pattern 202 when the conductive paste is printed from the front end to the rear end during manufacturing.Alternatively, the conductive paste can be printed such that it gradually slopes down towards the corner section of the end section 212 of the insulating pattern 202 from both sides of the end section 212 of the insulating pattern 202 in the lateral direction, if the conductive paste is printed in the opposite direction (from the rear end to the front end). Accordingly, in both cases, it is possible to increase the thickness of the transverse section m of the lead pattern 205, which extends over and across the end section 212 of the insulating pattern 202, relative to the thickness of the conventional gas sensor. Furthermore, the lead pattern 205 can gradually extend over and across the end section 212 of the insulating pattern 202.Therefore, it is possible to prevent the formation of cracks in the supply pattern 205, which extends over the end section 212 of the insulating pattern 202 and across it, even if the supply pattern 205 contracts during drying and firing.

[0036] Fig. Figure 5 is a top view showing an insulating layer 202 of a gas sensor 1 according to a third embodiment of the present invention. In this embodiment, the end section 212 of the insulating layer 202 has a recessed and raised shape, or concave-convex shape, comprising a plurality of raised sections that are raised in the longitudinal direction and a plurality of recessed sections that are recessed in the longitudinal direction. The conductive paste can be printed onto the insulating layer 202 thus formed with the recessed and raised end section 212 in such a way that it gradually rises in the width direction from a central section of each raised section of the end section 212 of the insulating layer 202 to the corner section of the end section 212 of the insulating pattern 202 when the conductive paste is printed from the front end to the back end during manufacturing.The conductive paste can, on the other hand, be printed such that it gradually slopes down towards the corner section of the end section 212 of the insulating pattern 202 on both sides of each recessed section of the end section 212 of the insulating pattern 202 in the lateral direction when the conductive paste is printed from the opposite direction (from the rear end to the front end). Accordingly, it is possible to increase the thickness of a transverse section m of the lead pattern 205, which extends over and across the end section 212 of the insulating pattern 202, relative to the thickness of the conventional gas sensor. Furthermore, the lead pattern 205 can gradually extend over and across the end section 212 of the insulating pattern 202.Therefore, it is possible to prevent the formation of cracks in the supply pattern 205, which extends over the end section 212 of the insulating pattern 202 and across it, even if the supply pattern 205 contracts during drying and firing.

[0037] In this way, in the first gas sensors 1 according to the first to third embodiments, the end sections 212 of the insulating layer 202, over and across which the lead section 205 of the sensor element 10 extends, have a recessed shape, a raised shape, and a recessed and raised shape. Accordingly, the thickness of the lead section 205, which extends over and across the end section 212 of the insulating layer 202, is increased. The lead section 205 gradually extends over and across the end section 212 of the insulating layer 202. Therefore, it is possible to prevent the formation of cracks in the lead section 205 during manufacturing and to accurately detect the concentration.

[0038] Preferably, the end section 212 of the insulating layer 202 has the recessed shape when comparing the recessed shape with the raised shape, although the shape of the end section 212 of the insulating layer 202 is not limited to the recessed shape. The recessed shape of the end section 212 of the insulating layer 202 prevents the conductive paste from protruding in the width direction from both sides of the end section 212 of the insulating pattern 202 when the conductive paste is printed on during manufacturing to form the lead pattern 205.

[0039] This means that the conductive paste is printed in such a way that the conductive paste is held together from both sides of the end section 212 of the insulating pattern 202 in the width direction towards the central section when the conductive paste is printed from the front end side to the rear end side and the end section 212 of the insulating layer 202 has the recessed shape as shown in Fig. Figure 3 shows that it is possible to prevent the conductive paste from protruding in the width direction from both sides. Conversely, the conductive paste is held in the width direction by the two side sections of the end section 212 of the insulating pattern 202 when the conductive paste is printed from the opposite direction. Therefore, it is possible to prevent any impairment of the appearance. Furthermore, it is possible to prevent unnecessary catalytic reactions (catalysis), etc., and to accurately determine the concentration.

[0040] A width W202 of the insulating layer 202 is, as in Fig. 3A, Fig. 4 and Fig. Figure 5 shows that the width W205 of the supply section 205 is greater than the width W205 of the supply section 205. Accordingly, it is possible to prevent the supply pattern 205 from projecting in the width direction from both sides of the insulating pattern 202. This prevents any impairment of the appearance. Furthermore, it is possible to prevent unnecessary catalytic reactions (catalysis), etc., and to accurately determine the concentration. The width W202 of the insulating layer 202 is preferably 1.1 times greater than the width W205 of the supply section 205.

[0041] The final section 205a of the supply section 205 contains, as shown in Fig. 3A, Fig. 4 and Fig. Figure 5 shows a wide section located near the end section 212 of the insulating layer 202, with a width that increases towards the rear end. That is, near the end section 212 of the insulating layer 202, the width W205a of the front end section 205a of the supply section 205 is greater than the width W205b of the rear end section 205b of the supply section 205. Thus, the supply section 205 has a wide section whose width increases towards the rear end. Accordingly, the supply section 205 can easily extend gradually over and across the end section 212 of the insulating layer 202. Furthermore, it is possible to prevent the formation of cracks in the supply section 205 and to accurately control their concentration.

[0042] Furthermore, the ratio (D202 / W202) of the depth (length) D202 to the width W202 of the end section 212 of the insulating layer 202 is preferably 0.1 or more if the end section 212 of the insulating layer 202 has the recessed shape as shown in Fig. Figure 3 shows. Furthermore, the ratio (D202 / W202) of the height (length) D202 to the width W202 of the end section 212 of the insulating layer 202 is preferably 0.1 or more if the end section 212 of the insulating layer 202 has the raised shape as shown in Figure 3. Fig. Figure 4 shows. Furthermore, the ratio (D202 / W202) of the height (length) D202 of each raised section to the width W202 of the end section 212 is preferably 0.1 or more, if the end section 212 of the insulating layer 202 has the recessed and raised shape as shown in Figure 4. Fig. 5 is shown. This makes it possible to effectively print the conductive paste onto the end section 212 of the insulating pattern 202 when the conductive paste is printed during manufacturing to form the lead-in pattern 205, and makes it possible to increase the thickness sufficiently.

[0043] Fig. Figure 6A is a top view showing an insulating layer 202 and a lead-in section 205 of a gas sensor 1 according to a fourth embodiment of the present invention. Fig. 6B is a section view along VIB-VIB of Fig. 6A. In this fourth embodiment, the supply line section 205 comprises a first supply line section 206 and a second supply line section 207. The first supply line section 206 comprises an end section 216 having a recessed or concave shape that is longitudinally recessed (concave) when viewed in the lamination direction. The first supply line section 206 comprises a front end section formed on the continuous electrolyte layer 201 and a rear end section formed over the insulating layer 202 on the continuous electrolyte layer 201. The first supply line section 206 includes the end section 216 at its front end, which has a recessed shape that is longitudinally recessed.The second supply section 207 includes a front end section formed directly on the continuous electrolyte layer 201, and a rear end section formed over the insulating layer 202 and the first supply section 206 on the continuous electrolyte layer 201.

[0044] The conductive paste can be printed onto the first lead-in section 206, which has a recessed end section 216, in such a way that it gradually rises in the width direction towards the corner section of the end section 216 of the first lead-in pattern 206 from both sides of the end section 216 of the first lead-in pattern 206 when the conductive plate is printed from the front end to the back end during manufacturing to form the second lead-in section 207. Conversely, the conductive paste can be printed in such a way that it gradually falls in the width direction towards the corner section of the end section 216 of the first lead-in pattern 206 from the middle section of the end section 216 of the first lead-in pattern 206 when the conductive paste is printed from the opposite direction (from the back end to the front end).Accordingly, in both cases it is possible to increase the thickness of a transverse section n of the second supply line pattern 207, which extends over and transversely to the end section 216 of the first supply line pattern 206, relative to the thickness of the conventional gas sensor. Furthermore, a gradual progression over and transversely to the end section 216 of the first supply line pattern 206 is possible. Therefore, it is possible to prevent the formation of cracks in the second supply line pattern 207, which extends over and transversely to the end section 216 of the first supply line pattern 206, even if the second supply line pattern 207 contracts during drying and firing.

[0045] Fig. Figure 7 is a top view showing an insulating layer 202 and a lead-in section 205 of a gas sensor 1 according to a fifth embodiment of the present invention. In the fifth embodiment, the end section 216 of the first lead-in section 206 has a raised or convex shape, which, viewed in the lamination direction, is raised or convex in the longitudinal direction. The conductive paste can be printed onto the first lead-in section 205 with the raised end section 216 in such a way that it gradually rises in the lateral direction from the central section of the end section 216 of the first lead-in pattern 206 towards the corner section when, during manufacturing, the conductive paste is printed from the front end to the rear end to form the second lead-in pattern 207.Alternatively, the conductive paste can be printed such that it gradually slopes down towards the end section 216 of the first supply pattern 206 from both sides of the end section 216 of the first supply pattern 206 in the lateral direction, if the conductive paste is printed from the opposite direction (from the rear end to the front end). Accordingly, in both cases, it is possible to increase the thickness of the transverse section n of the second supply pattern 207, which extends over and across the end section 216 of the first supply pattern 206, relative to the thickness of the conventional gas sensor. Furthermore, a gradual slope across and across the end section 216 of the first supply pattern 206 is possible.Therefore, it is possible to prevent the formation of cracks in the second feeder pattern 207, which extends over the end section 216 of the first feeder pattern 206 and transversely thereto, even if the second feeder pattern 207 contracts during drying and firing.

[0046] Fig. Figure 8 is a top view showing an insulating layer 202 and a lead-in section 205 of a gas sensor 1 according to a sixth embodiment of the present invention. In the sixth embodiment, the end section 216 of the first lead-in section 206 has a recessed and raised shape (concave-convex shape) comprising a plurality of raised sections that are raised in the longitudinal direction and a plurality of recessed sections that are recessed in the longitudinal direction.The conductive paste can be printed onto the first lead-in section 206, with its recessed and raised end section 216, such that it gradually rises in the width direction from the central section of each raised section of the end section 216 of the first lead-in pattern 206 to the corner section of the end section 216 of the first lead-in pattern 206 when, during manufacturing, the conductive paste is printed from the front end to the back end to form the second lead-in pattern 207. Furthermore, the conductive paste can be printed such that it gradually slopes down in the width direction from both sides of each recessed section of the end section 216 of the first lead-in pattern 206 to the corner section of the end section 216 of the first lead-in pattern 206 when the conductive paste is printed from the opposite direction (from the back end to the front end).Accordingly, in both cases it is possible to increase the thickness of the transverse section n of the second supply line pattern 207, which extends over and transversely to the end section 216 of the first supply line pattern 206, relative to the thickness of the conventional gas sensor. Furthermore, a gradual progression over and transversely to the end section 216 of the first supply line pattern 206 is possible. Therefore, it is possible to prevent the formation of cracks in the second supply line pattern 207, which extends over and transversely to the end section 216 of the first supply line pattern 206, even if the second supply line pattern 207 contracts during drying and firing.

[0047] In embodiments four to six, the supply line section 205 comprises the first supply line section 206 and the second supply line section 207. Accordingly, high performance can be achieved by dividing the function. For example, if the second supply line section 207, which is connected to the electrode section 204, consists mainly of precious metal, as in the conventional gas sensor, it is possible to form the second supply line section 207 by simultaneously printing the conductive paste onto the electrode section 204, for which catalysis is required. Furthermore, it is possible to reduce the use of precious metal in the first supply line section 206, which is connected to the electrode connection section 41. The second supply line section 207 also extends over and transversely to the end section 216 of the first supply line section 206.Accordingly, it is possible to ensure the electrical connection between the first supply line section 206 and the second supply line section 207.

[0048] Furthermore, the end section 216 of the first supply section 206, over which and transversely to which the second supply section 207 extends, has the recessed form, the raised form, and the recessed and raised form. Accordingly, it is possible to prevent the formation of cracks in the transverse section of the second supply section 207, which extends over and transversely to the end section 216 of the first supply section 206. Furthermore, it is possible to accurately determine the concentration.

[0049] Furthermore, when comparing the recessed shape with the raised shape, the end section of the first lead section 206 preferably has the recessed shape, although the shape of the end section is not limited to the recessed shape. The recessed shape of the end section 216 of the first lead section 206 prevents the conductive paste from protruding in the width direction from both sides of the end section 216 of the first lead pattern 206 when the conductive paste is printed onto the sensor element 10 to form the second lead pattern 207.

[0050] That is, the conductive paste is printed in such a way that the conductive paste is held together in the width direction from both sides of the end section 216 of the first lead pattern 206 towards the central section when the conductive paste is printed from the front end side to the rear end side and the end section 216 of the first lead section 206 has the recessed shape as shown in Fig. Figure 6 is shown. Accordingly, it is possible to prevent the conductive paste from protruding in the lateral direction. Furthermore, the conductive paste is held in the lateral direction by the two side sections of the end section 216 of the insulating pattern 206. Therefore, it is possible to prevent impairment of the external appearance, to prevent unnecessary catalytic reaction (catalysis), etc., and to accurately control the concentration.

[0051] Furthermore, the ratio (D206 / W206) of the length (depth) D206 to the width W206 of the end section 216 of the first supply section 206 is preferably 0.1 or more if the end section 216 of the first supply section 206 has the recessed shape as shown in Fig. Figure 6 shows that the ratio (D206 / W206) of the length (height) D206 to the width W206 of the end section 216 of the first supply section 206 is preferably 0.1 or more if the end section 216 of the first supply section 206 has the raised shape shown in Figure 6. Fig. Figure 7 shows. Furthermore, the ratio of the length (height) D of each raised section to the width W206 of the end section 216 of the first supply section 206 is preferably 0.1 or more, if the end section 216 of the first supply section 206 has the recessed and raised shape as shown in Figure 7. Fig. Figure 8 shows that with the gas sensor thus formed, it is possible to effectively print the conductive paste onto the end section 216 of the first supply pattern 206 when the conductive paste is printed during manufacturing to form the second supply pattern 207, and it is possible to increase the thickness sufficiently.

[0052] Furthermore, the width W206 of the first supply section 206, which is formed on the side of the continuous electrolyte layer 201, is preferably larger than the width W207 of the second supply section 207, as shown in Fig. 6a, Fig. 7 and Fig. Figure 8 shows this. Furthermore, for example, the width W206 of the first lead-in section 206 is preferably 1.1 times greater than the width W207 of the second lead-in section 207. In this way, the width W206 of the first lead-in section 206, which is generally formed upstream of the second lead-in section 207, is greater than the width W207 of the second lead-in section 207, which is formed downstream of the first lead-in section 206. Accordingly, it is possible to prevent the conductive paste from protruding in the width direction from both sides of the first lead-in pattern 206 when the conductive paste is printed on during manufacturing to form the second lead-in pattern 207.

[0053] The end section 216 of the first supply section 206 is located at a position that differs from the position of the end section 212 of the insulating layer 202, as shown in Fig. 6A, Fig. 7 and Fig. Figure 8 shows that in a case where the end section 216 of the first supply line section 206 is located directly above the end section 212 of the insulating layer 202, this overlapping section has a complex shape. Consequently, the sensor element 10 tends to break. Furthermore, the second supply line section 207 must extend over the end section 212 of the insulating layer 202 and simultaneously over and transversely to the end section 216 of the first supply line section 206. Therefore, the portion of the second supply line section 207 that extends over and transversely to the end section of the insulating layer and the end section of the first supply line section becomes raised, and cracks can occur during manufacturing. In contrast, in the embodiments described above, the sensor element 10 has a simple shape and does not break.Furthermore, it is not necessary for the second supply section 207 to extend simultaneously over the end section 212 of the insulating layer 202 and the end section 216 of the first supply section 206. Therefore, it is possible to prevent the formation of cracks in the supply section 205.

[0054] Preferably, the end section 216 of the first supply line section 206 is formed at the front end section 205a of the supply line section 205, as shown in Fig. 6A, Fig. 7 and Fig. Figure 8 is shown. As a result, the sensor element 10 does not have the additional thickness, and the surface protective layer 140 is laminated onto the continuous electrolyte layer 201 without the gap.

[0055] Furthermore, the second supply section 207 preferably extends over the end section 212 of the insulating layer 202 and transversely thereto, as shown in Fig. 6A, Fig. 7 and Fig.Figure 8 shows that this makes it possible to improve the reliability of the electrical connection between the first supply line section 205 and the second supply line section 207.

[0056] The present invention is not limited to the embodiments described above. It is possible to modify the gas sensors according to these embodiments. In these embodiments, the gas sensor element is the oxygen sensor element. However, the sensor element is not limited to the oxygen sensor element. For example, the sensor element can be a NOx sensor element configured to detect the concentration of NOx.

[0057] In the gas sensor according to the embodiments of the present invention, a gas sensor comprises a generally cylindrical metal sleeve 2 and a laminated sensor element 10 which is received in the metal sleeve 2, wherein the sensor element 10 comprises a plate-shaped continuous electrolyte layer 201 extending in a longitudinal direction, an electrode section 204 which is present on the continuous electrolyte layer 201, an insulating layer 202 and a lead section 205 which is connected to the electrode section 204, wherein the lead section 205 extends in the longitudinal direction and has a front end section 205a which is laminated onto the continuous electrolyte layer 201, and a rear end section 205b which is laminated onto the continuous electrolyte layer 201 via the insulating layer 202, the insulating layer 202 having an end section 212,over and across which the supply section 205 extends and which, viewed in the lamination direction, has a recessed form, a raised form or a recessed and raised form in the longitudinal direction.

[0058] In the gas sensor according to the embodiments of the present invention, the end section of the insulating layer, over and transversely to which the lead section extends, has, viewed in the lamination direction, a recessed shape, a raised shape, or a recessed and raised shape in the longitudinal direction. Accordingly, the thickness of the lead section, which extends over and transversely to the end section of the insulating layer, increases. Furthermore, the lead section gradually extends over and transversely to the end section of the insulating layer. Therefore, it is possible to prevent the formation of cracks in the lead section during manufacturing and to accurately detect the concentration.

[0059] In the gas sensor according to the embodiments of the present invention, the insulating layer 202 has a width W202 in a direction perpendicular to the longitudinal direction, which is greater than the width W205 of the supply line section 205 in the direction perpendicular to the longitudinal direction. Accordingly, it is possible to prevent the supply line section from protruding from both sides of the insulating layer in the lateral direction. This prevents any impairment of the appearance. Furthermore, it is possible to prevent unnecessary catalytic reactions (catalysis), etc., and to accurately measure the concentration.

[0060] In the gas sensor according to the embodiments of the present invention, the front end section 205a of the supply line section 205, which is located closer to the end section 212 of the insulating layer 202, has a width W205a that is greater than the width W205b of the rear end section 205b of the supply line section 205. The supply line section has a wide front end section (beveled front end section). Accordingly, a gradual progression across and perpendicular to the end section of the insulating layer is possible. Furthermore, it is possible to further prevent the formation of cracks in the supply line section and to accurately measure the concentration.

[0061] In the gas sensor according to the embodiments of the present invention, the end section 212 of the insulating layer 202 has a D / W ratio ≥ 0.1, where W represents a width W202 of the insulating layer 202 and D represents a longitudinal length between a front end and a rear end of the end section 212 of the insulating layer 202. Accordingly, it is possible to sufficiently increase the thickness of the supply line section, which extends over the end section of the insulating layer and transversely thereto. Furthermore, it is possible to further suppress the formation of cracks in the supply line section and to accurately detect the concentration.

[0062] In the gas sensor according to the embodiments of the present invention, the supply line section 205 comprises a first supply line section 206, which has an end section 216 which, viewed in the lamination direction, has a recessed shape, a raised shape or a recessed and raised shape in the longitudinal direction, and a second supply line section 207, which extends over the end section 216 of the first supply line section 206 and transversely thereto.

[0063] It is considered that the supply line section is divided into a front end section (second supply line section), which is connected to the electrode section, and a rear end section (first supply line section) to conserve precious metal, such as platinum. That is, the rear end section of the supply line does not require catalysis, and its purpose is to provide an electrical connection between the electrode section and the outside. Consequently, the consumption of precious metal in the rear end section of the supply line can be reduced. Furthermore, the front end section of the supply line serves as a connection point for the electrode section.The front end section of the lead section is formed by printing the conductive paste simultaneously with the formation of the electrode section.

[0064] In a case where the sensor lead section is divided in this way, an end section of the front end, which is a connecting section, must be positioned over an end section of the rear end to ensure the electrical connection. In this case, the end section of the first lead section has a recessed shape, a raised shape, and a combination of recessed and raised shapes in the longitudinal direction. Accordingly, the thickness of the second lead section, which extends over and across the end section of the first, increases. The second lead section gradually extends over and across the end section of the first lead section. Therefore, it is possible to prevent the formation of cracks in the lead section during manufacturing and to accurately measure the concentration.

[0065] In the gas sensor according to embodiments of the present invention, the end section 212 of the insulating layer 202 is located in a position that differs from the position of the end section 216 of the first supply line section 206 in the longitudinal direction of the sensor element 10. In a case where the end section of the first supply line section overlaps the end section of the insulating layer, the overlapping section has a complex shape. The sensor element may break. Furthermore, the second supply line section must extend simultaneously over the end section of the insulating layer and the end section of the first supply line section, and transversely thereto. Accordingly, the portion of the second supply line section that extends over the end section of the insulating layer and the end section of the first supply line section, and transversely thereto, becomes raised, and cracks may occur during manufacturing.In contrast, in the gas sensor according to the embodiment of the present invention, the sensor element has a simple shape and does not break. Furthermore, it is not necessary for the second lead section to extend simultaneously over and across the end section of the insulating layer and the end section of the first lead section. Accordingly, the formation of cracks in the lead section can be prevented.

[0066] In the gas sensor according to the embodiments of the present invention, the end section 216 of the first supply line section 206 is formed in the front end section 205a of the supply line section 205. Accordingly, it is possible to laminate other layers onto the continuous electrolyte layer in order to cover the supply line section and the insulating layer without a gap between the continuous electrolyte layer and the other layers.

[0067] In the gas sensor according to the embodiments of the present invention, the second lead section 207 extends over and transversely to the end section 212 of the insulating layer 202. The end section of the insulating layer is arranged close to the electrode section in order to separate the lead section from the continuous electrolyte layer. Therefore, the end section of the first lead section is located close to the rear end section of the insulating layer. In this case, the second lead section extends over and transversely to the end section of the insulating layer. Therefore, it is possible to improve the electrical connection between the first lead section and the second lead section.

[0068] In the gas sensor according to the embodiments of the present invention, the gas sensor element 10 is a NOx sensor element which is configured to detect a NOx concentration.

[0069] The entire contents of Japanese patent application No. 2008-178999, filed on July 9, 2008, and Japanese patent application No. 2009-130245, filed on May 29, 2009, are hereby incorporated by reference.

[0070] Although the invention has been described above with reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Variations and modifications of the embodiments described above are obvious to a person skilled in the art based on the teachings presented. The scope of the invention is defined by the following claims.

Claims

[1] Gas sensor comprising: a substantially cylindrical metal sleeve (2); a laminated sensor element (10) which is received in the metal sleeve (2), wherein the sensor element (10) contains: a plate-shaped continuous electrolyte layer (201) extending in a longitudinal direction; an electrode section (204) laminated onto the continuous electrolyte layer (201); and a lead section (205) which is connected to the electrode section (204), and extends in the longitudinal direction, wherein the sensor element includes an insulating layer (202) laminated onto the continuous electrolyte layer (201); and the lead section includes a front end section (205a) laminated onto the continuous electrolyte layer (201), as well as having a rear end section (205b) which is laminated over the insulating layer (202) onto the electrolyte layer (201), and wherein the insulating layer (202) has an end section (212) over which and transversely to which the supply section (205) extends and which, viewed in the lamination direction, has a recessed shape, a raised shape or a recessed and raised shape in the longitudinal direction. [2] Gas sensor according to claim 1, wherein the insulating layer (202) has a width (W202) in a direction perpendicular to the longitudinal direction which is greater than a width (W205) of the supply section (205) in the direction perpendicular to the longitudinal direction. [3] Gas sensor according to claim 2, wherein the front end section (205a) of the supply section (205), which is located near the end section (212) of the insulating layer (202), has a width (W205a) that is greater than a width (W205b) of the rear end section (205b) of the supply section (205). [4] Gas sensor according to any one of claims 1 to 3, wherein the end section (212) of the insulating layer (202) satisfies a relationship D / W ≥ 0.1, where W represents a width (W202) of the insulating layer (202) and D represents a length between a front end and a rear end of the end section (212) of the insulating layer (202) in the longitudinal direction. [5] Gas sensor according to one of claims 1 to 4, wherein the supply line section (205) comprises a first supply line section (206) having an end section (216) which, viewed in the lamination direction, has a recessed shape, a raised shape or a recessed and raised shape in the longitudinal direction, and a second supply line section (207) which extends over the end section (216) of the first supply line section (206) and transversely thereto. [6] Gas sensor according to claim 5, wherein the end section (212) of the insulating layer (202) is located in a position that differs from a position of the end section (216) of the first supply line section (206) in the longitudinal direction of the sensor element (10). [7] Gas sensor according to claim 6, wherein the end section (216) of the first supply section (206) is formed in the front end section (205a) of the supply section (205). [8] Gas sensor according to claim 7, wherein the second supply line section (207) extends over the end section (212) of the insulating layer (202) and transversely thereto. [9] Gas sensor according to any one of claims 1 to 8, wherein the gas sensor element (10) is a NOx sensor element configured to detect a NOx concentration.

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