JP2005338091A - Sensor element for gas measurement sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor element inside a gas measurement sensor, wherein a fault of conventional technology is improved. <P>SOLUTION: An area of a penetration guidance part 25 is disposed with a cover layer 51, thereby gas positioned outside the sensor element 10 can arrive into the sensor element 10 only through a prescribed diffusion distance, and the diffusion distance extends partially parallel to the outside 24 of a solid electrolyte layer 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The invention relates to a sensor element, in particular for detecting the physical properties of the measuring gas, preferably for detecting the concentration of the gas component of the measuring gas or the temperature of the measuring gas. Provided in the measurement sensor, the sensor element is provided with a solid electrolyte layer having a penetration guide portion and a conductor path, and the conductor path is disposed outside the solid electrolyte layer; and The present invention relates to a type having a through guide section disposed in the through guide section and a supply section connected to the through guide section.

  This type of long planar sensor element, gas tightly fixed in the housing of the gas measuring sensor, is structured in layers and has a plurality of solid electrolyte layers. This sensor element has a termination section on the measurement side and a termination section on the connection side. The termination section on the measuring side, which is arranged inside a protective tube fixed to the housing and is exposed to the measuring gas, has sensor elements, for example one or more electrochemical cells and heaters. One electrochemical cell has two electrodes, each of which is applied to a solid electrolyte and is electrically connected by a stationary electrolyte.

  The electrodes and the heater are each electrically connected to one or more supply sections. The one or more supply sections are guided from the electrode or heater along the longitudinal extension of the sensor element to the terminal section on the connection side of the sensor element. If the supply section extends in the layer plane inside the sensor element, i.e. between the two solid electrolyte layers, the supply section is placed outside the sensor element by means of a through-guide section arranged in the penetration. It is electrically connected to the arranged outer section. Thereby, the electrode, the supply section, the penetration guide section and the outer section form an associated conductor track. The heater has two supply parts, which are likewise connected to the outer section by means of through guide sections, respectively. The outer section has a contact surface. Through this contact surface, the sensor element can be electrically connected to an evaluation electronic mechanism arranged outside the gas measurement sensor.

  The penetration guide is formed in the form of a cylindrical hole provided in at least one solid electrolyte sheet. The wall of the penetration guide part is covered with the penetration guide section, and in this case, one or a plurality of insulating layers may be provided between the penetration guide section and the wall. Similarly, the outer section and / or the supply section are electrically insulated from the solid electrolyte sheet by at least one insulating layer.

  The insulating layer and the conductor path are formed to be porous and thus gas permeable. Therefore, the gas located outside the terminal section on the connection side reaches the terminal section on the measurement side of the sensor element via the penetration guide part of the conductor path and the supply section or the insulating layer provided in the area of the supply section. . In this case, the gas inflow into the sensor element is performed in a diffusion direction perpendicular to the large surface of the sensor element.

  This type of sensor element often has a reference electrode. The reference electrode is exposed to a reference gas, i.e. a gas having a high oxygen content. The reference electrode is exposed to the reference air in a simple manner by being connected to the air atmosphere at the end of the connection side of the sensor element via a conductor track or an insulating layer.

  In this type of sensor element, the gas located outside the termination section on the connection side of the sensor element may contain impurities, for example water or fuel, which penetrates without being blocked. It has the disadvantage that it can enter the guide and from there into the porous conductor track or the porous insulating layer. Furthermore, it is particularly inconvenient that these impurities can accumulate on the penetration guide.

  When such impurities reach the heater or electrode, the measurement function of the sensor element is disturbed. If water enters the end section on the measurement side of the sensor element, in particular in the area of the heater, this water can cause destruction of the sensor element. Particularly when the fuel reaches the region of the reference electrode, the oxygen content in the reference air is reduced, thereby impairing the measurement function of the sensor element.

  The object of the present invention is to provide a sensor element in a gas measuring sensor in which the disadvantages of the prior art are improved.

  According to the means of the present invention that solves this problem, the cover layer is disposed in the region of the penetration guide portion, whereby the gas located outside the sensor element is allowed to flow into the sensor element at a predetermined diffusion distance. And the diffusion distance extends partially parallel to the outside of the solid electrolyte layer.

  The sensor element according to the present invention having the features according to claim 1 is characterized in that, on the one hand, a gas path located outside the terminal section on the connection side of the sensor element is arranged inside the sensor element via a penetration guide. And / or has the advantage that it is difficult to penetrate into the insulating layer, while on the other hand it is prevented that impurities can accumulate in the penetration guide.

  The sensor element has a solid electrolyte layer having a penetration guide. Further, the sensor element has a conductor path, and the conductor path is connected to the outer section disposed outside the solid electrolyte layer, the penetrating guide section disposed in the penetrating guide portion, and the penetrating guide section. Supply categories.

  According to the present invention, the penetrating guide and / or the region outside the solid electrolyte layer adjacent to the penetrating guide is covered with a cover layer in the following form, that is, the gas located outside the sensor element is The sensor element is covered in such a way that it can only reach the inside of the sensor element via a predetermined diffusion distance. This diffusion distance extends at least partially parallel to the outside of the solid electrolyte layer. Thereby, the gas cannot reach directly into the layer plane of the supply section, but can only reach, for example, via a diffusion distance extending parallel to the outside of the sensor element. That is, this diffusion distance extends first along the layer deposited on the outside of the sensor element and then to the layer plane of the feed section in a direction perpendicular to the outside of the sensor element via the penetration guide. .

  By means of the dependent claims, advantageous developments of the sensor elements according to the independent claims are possible.

  Advantageously, the cover layer is gas tight, so that the gas located outside the sensor element can only pass through a predetermined diffusion distance extending at least partly parallel to the outside of the solid electrolyte layer. Can reach the inside. On the other hand, gas inflow through the cover layer is completely prevented. Furthermore, the conductor track and / or the insulating layer are preferably made porous.

  The conductor track is preferably an insulating layer from the outside of the solid electrolyte layer and / or from the region of the penetration guide of the solid electrolyte layer and / or from one or more solid electrolyte layers adjacent to the supply region of the conductor track. It is separated by. This prevents electrical connection into the conductor track via the solid electrolyte.

  Advantageously, an insulating layer is arranged between the cover layer and the conductor track. This prevents interference with the measurement function, especially when the cover layer is electrically conductive. The cover layer contains, for example, zirconium oxide stabilized by a solid electrolyte material such as yttrium oxide. This zirconium oxide is ionic and electrically conductive.

  Advantageously, the cover layer covers a region of the conductor track, the penetration guide as well as the outer section, in which case the outer section has a region which acts as a contact surface, in which the cover layer is Has a recess. The cover layer may be applied to the penetration guide section in the form of a layer or may completely fill the penetration guide. As an alternative, the cover layer is preferably arranged in a layer plane parallel to the outside of the first solid electrolyte layer, and covers the opening of the penetration guide and the area of the outer section of the conductor track. Covering. In another advantageous configuration of the invention, the through guide section of the conductor track completely fills the through guide and the cover layer is in the form of a layer arranged parallel to the outside of the solid electrolyte layer. Covering.

  Embodiments of the invention will now be described in more detail with reference to the drawings.

  1, FIG. 2 and FIG. 3 show a termination section on the connection side of the sensor element 10 as a first embodiment of the present invention. The sensor element 10 is disposed in a gastight manner in the housing of the gas measurement sensor and is used, for example, for measuring the oxygen concentration in the exhaust gas of the internal combustion engine or for measuring the temperature.

  The sensor element 10 has a first solid electrolyte layer 21 and a second solid electrolyte layer 22. The first solid electrolyte layer 21 and the second solid electrolyte layer 22 are made of zirconium oxide stabilized by yttrium oxide. A cylindrical through guide portion 25 is provided in the first solid electrolyte layer 21. The sensor element 10 has a conductor path 31. The conductor path 31 has a supply section 31c, a penetration guide section 31b, and an outer section 31a. Furthermore, the conductor path 31 has an electrode or a heater (not shown) in the terminal section on the measurement side of the sensor element 10. The conductor track 31 is made of a cermet having a metal part, for example, platinum and a ceramic part. The configuration of such sensor elements, particularly the configuration of the termination section on the measurement side and the mounting of the sensor elements in the gas measurement sensor are also described, for example, in Electronics Handbook, Second Edition, Editor: Ronald K. Juergen, McGraw-Hill, 1999. ing. As can be seen in this publication, the sensor element may have a further solid electrolyte layer.

  The electrode or heater is connected to the outer section 31a by a supply section 31c disposed between the first solid electrolyte layer 21 and the second solid electrolyte layer 22 and a penetration guide section 31b. The outer section 31 a is disposed on the outer side 24 of the first solid electrolyte layer 21. The penetration guide section 31 b of the conductor path 31 is formed in the form of a layer provided on the wall of the cylindrical penetration portion 25.

  The outer section 31a of the conductor path 31 has a region that functions as a contact surface 31d. This region can be electrically connected to a conductor element guided outwardly from the gas measurement sensor, whereby the sensor element 10 can be connected to an evaluation electron arranged outside the gas measurement sensor. Connected to the mechanism.

  The supply section 31 c of the conductor path 31 is embedded in the first insulating layer 41, and the first insulating layer 41 electrically connects the first solid electrolyte layer 21 and the second solid electrolyte layer 22. Insulated. The first insulating layer 41 is laterally surrounded by a seal frame 45 made of a gas tight material. On the outer side 24 of the first solid electrolyte layer 21, the outer section 31 a of the conductor path 31 and thus the contact layer 31 d are also separated from the first solid electrolyte layer 21 by the second insulating layer 42.

  The outer section 31 a and the penetration guide section 31 b of the conductor path 31 are covered with a gas-tight cover layer 51. For this purpose, the cover section 51 may be formed in the form of a covering layer for the penetration guide section 31b or may completely fill the penetration guide 25. The cover layer 51 has a recess in the region of the contact surface 31d. As a result, the gas located outside the terminal section on the measurement side of the sensor element 10 can be moved only along the outer section 31a and the penetration guide section 31b of the conductor path 31 or only along the second insulating layer 42. It can reach the layer plane between one solid electrolyte layer 21 and the second solid electrolyte layer 22. Therefore, the cover layer 51 is arranged as follows, that is, the diffusion distance is partially outside, that is, outside the first solid electrolyte layer 21 in the second insulating layer 42 or in the outer section of the conductor path 31. 24 are arranged so as to extend in parallel to 24.

  FIG. 4 shows a sensor element 10 as a second embodiment of the present invention. In this case, a third insulating layer 43 is additionally provided with respect to the first embodiment according to FIGS. The insulating layer 43 is provided between the outer section 31 a or the penetration guide section 31 b of the printed wiring board 31 and the cover layer 51. Thus, the gas can reach the layer plane between the first solid electrolyte layer 21 and the second solid electrolyte layer 22 even through the third insulating layer 43. The diffusion distance also extends parallel to the outer side 24 of the first solid electrolyte layer 21 through the third insulating layer 43.

  The configuration of the third embodiment shown in FIG. 5 corresponds to the configuration of the first embodiment according to FIGS. 1 to 3, but the cover layer 51 is not disposed inside the penetration guide portion 25, Thereby, only the outer section 31a of the conductor path 31 is covered, however, it is different in that it does not cover the penetration guide section 31b. The cover layer 51 completely covers the opening formed by the penetrating part 51 in the plane of the outer side 24 of the first solid electrolyte layer 21.

  The fourth embodiment of the invention shown in FIG. 6 corresponds to the third embodiment according to FIG. In this embodiment, a third insulating layer 43 is additionally provided between the cover layer 51 and the outer section 31 a of the conductor path 31. The third insulating layer 43 covers the cover layer 51 and the opening formed by the penetration guide portion 25.

  FIG. 7 shows a fifth embodiment of the present invention. In this embodiment, the penetration guide section 31 b of the conductor path 31 completely fills the penetration guide portion 25. The cover layer 51 covers the outer section 31a of the conductor track 31 and has a recess for the contact surface 31d as in the embodiment already described above. The sensor element 10 shown as the sixth embodiment in FIG. 8 is the fifth embodiment because the third insulating layer 43 is additionally provided between the cover layer 51 and the outer section 31 a of the conductor path 31. It is different from the example.

  The first, second, and third insulating layers 41, 42, and 43 contain, for example, aluminum oxide and are made porous. The cover layer has a densely sintered material, i.e. gas tight, for example with zirconium oxide stabilized by yttrium oxide.

  The cover layer is applied by screen printing, suction or spraying, metering for adhesive media (micro metering), or plasma forming. This type of method is generally known to those skilled in the art. In the embodiment according to FIGS. 5 and 6, the hollow chamber located below the cover layer 51 is first filled with so-called hollow chamber paste inside the penetration guide 25 and then the cover layer 51 is (for example by screen printing). The second insulating layer 42, the outer section 31a of the conductor path 31, and the hollow chamber paste are applied. For example, by heat treatment within the frame of the sintering process, the hollow chamber paste then vaporizes and leaves the hollow chamber shown in FIGS.

  In the embodiments, the gas diffused into the layer plane between the first solid electrolyte layer 21 and the second solid electrolyte layer 22 is a predetermined section (i.e., the outer section 31a and the outer section 31a of the conductor track). Crossing the second insulating layer 42 and / or the third insulating layer 43), in which the gas diffusion direction extends parallel to the outer side 24 of the first solid electrolyte layer 21. It is common.

  One skilled in the art can optionally transfer the present invention to other configurations, for example, sensor elements having more than two solid electrolyte layers. The invention can generally be used for sensor elements having a conductor path guided through a penetration guide.

FIG. 3 is a longitudinal cross-sectional view of the terminal end of the connection side of the first embodiment of the sensor element according to the present invention. It is the top view of 1st Example seen in the direction II of FIG. It is a cross-sectional view of the first embodiment along the line III-III in FIG. FIG. 6 is a longitudinal cross-sectional view of a connection-side end portion of another embodiment of a sensor element according to the present invention. FIG. 6 is a longitudinal cross-sectional view of a connection-side end portion of another embodiment of a sensor element according to the present invention. FIG. 6 is a longitudinal cross-sectional view of a connection-side end portion of another embodiment of a sensor element according to the present invention. FIG. 6 is a longitudinal cross-sectional view of a connection-side end portion of another embodiment of a sensor element according to the present invention. FIG. 6 is a longitudinal cross-sectional view of a connection-side end portion of another embodiment of a sensor element according to the present invention.

Explanation of symbols

  10 sensor elements, 21 first solid electrolyte layer, 22 second solid electrolyte layer, 24 outside, 25 penetration guide, 31 conductor path, 31a outside section, 31b penetration guide section, 31c supply section, 41, 42, 43 Insulation layer, 45 seal frame, 51 cover layer

Claims (14)

  Sensor element (10), in particular for detecting the physical properties of the measuring gas, preferably for detecting the concentration of the gas component of the measuring gas or the temperature of the measuring gas. The sensor element (10) is provided with a solid electrolyte layer (21) having a penetrating guide portion (25) and a conductor path (31), and the conductor path (31) is an outer section (31a) disposed on the outer side (24) of the solid electrolyte layer (21), a penetration guide section (31b) disposed in the penetration guide portion (25), and the penetration guide. In the type having the supply section (31c) connected to the section (31b), the cover layer (51) is arranged in the region of the penetration guide (25), whereby the sensor element (10) Outside The located gas can reach the inside of the sensor element (10) only through a predetermined diffusion distance, and the diffusion distance is outside the solid electrolyte layer (21) (24). Sensor element (10), characterized in that it extends partially parallel to the sensor element (10).   The sensor element according to claim 1, wherein the cover layer is gas tight.   The sensor element according to claim 1 or 2, wherein the conductor path (31) is formed to be porous.   Sensor element according to any one of claims 1 to 3, wherein the conductor track (31) is at least partly separated from the first solid electrolyte layer (21) by an insulating layer (41, 42). .   The supply section (31c) of the conductor path (31) is disposed between the solid electrolyte layer (21) and another solid electrolyte layer (22), and the supply section (31c) is the solid electrolyte layer (21). 5. The sensor element according to claim 1, wherein the sensor element is separated from the other solid electrolyte layer (22) by the first insulating layer (41) and is electrically insulated.   The second insulating layer (42) is provided between the outer section (31a) of the conductor track (31) and the outer side (24) of the solid electrolyte layer (21). The sensor element of any one of Claims.   The sensor element according to any one of claims 1 to 6, wherein a third insulating layer (43) is provided at least partially between the conductor track (31) and the cover layer (51).   The first solid electrolyte layer (41) and / or the second solid electrolyte layer (42) and / or the third solid electrolyte layer are formed to be porous. The sensor element according to item.   The gas located outside the sensor element (10) is porous conductor track (31), in particular the porous outer section (31a) of the conductor track (31) and / or the porous second insulation (42). ) And / or through the porous third insulating layer (43) and diffused into the sensor element (10), the direction of gas diffusion depends on the outer section (31a) and / or the second insulating layer ( 42) and / or extending in the direction of the third insulating layer (43), i.e. parallel to the outside (24) of the solid electrolyte layer (21). The sensor element described.   The through guide section (31b) of the conductor path (31) covers the wall of the through guide section (25) in layers, and the cover layer (51) is a region of the through guide section (31) of the conductor path (31). 10. The sensor element according to claim 1, wherein the sensor element covers the outer section (31 a) of the conductor path (31).   The cover layer (51) is a layer covering the penetration guide part (25) and the outer section (31a) of the conductor path (31), and the layer is a predetermined layer plane of the solid electrolyte layer (21). 10. A sensor element according to claim 1, wherein the sensor element is arranged parallel to the outer side (24). The outer section (31a) of the conductor path (31) has a contact surface (31d), and the cover layer (51) has a recess in the region of the contact surface (31d).
The sensor element according to any one of claims 1 to 11.   The sensor element according to any one of claims 1 to 12, wherein the penetration guide section (31b) of the conductor path (31) covers the inner surface of the penetration guide portion (25) in layers.   12. Sensor element according to claim 11, wherein the penetration guide section (31b) of the conductor track (31) completely fills the penetration guide (25).

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