JP2744495B2 - Gas detection sensor - Google Patents

Description

The present invention relates to a gas detection sensor for detecting a gas component in a gas to be measured and / or its gas concentration.

[Prior Art] Conventionally, this type of gas detection sensor integrally stores a substrate having a sensor element together with an electrode wire for outputting a detection result of the sensor element to an outside in, for example, a stainless steel housing. Is installed in an internal combustion engine or the like that generates a gas to be measured.

[Problems to be Solved by the Invention] However, the conventional gas detection sensor has the following problems.

For example, in an oxygen sensor mounted on a vehicle, according to the shape, size, installation position, and the like of the internal combustion engine to be measured,
The size and shape of the sensor itself were changed. Specifically, the length of the substrate having the sensor element is changed according to the diameter of the exhaust pipe of the internal combustion engine, or the shape and length of the storage portion of the electrode wire are changed according to the installation state of peripheral devices outside the internal combustion engine. Has changed.

Since the shape of the sensor itself is changed in accordance with the shape of the internal combustion engine in this way, even if the sensor element alone is damaged or the electrode wire is broken, the entire sensor is replaced with a new one. There is a need. That is, the design of the sensor is limited by the internal combustion engine to be installed, and the degree of freedom is limited. For this reason, not only is the versatility low, but also the cost is increased.

The present invention has been made to solve the above problems, and has as its object to increase the versatility and design freedom in using a sensor.

MEANS FOR SOLVING THE PROBLEMS In order to achieve the above object, a means adopted by the present invention is to provide a sensor element which emits an electric signal according to a surrounding gas component and / or its gas concentration, and A gas detection substrate having a lead terminal connected to the sensor element; and a lead portion having an electrode wire connected to the lead terminal and outputting an electrical signal of the sensor element to the outside, the lead portion and the A gas detection sensor in which a gas detection board is stored in a housing, wherein the housing includes an upper housing and a lower housing that can be divided into upper and lower parts, and the gas detection board exposes the lead terminals to the upper housing. Then, a ceramic material is housed and provided in the lower housing in an airtight manner, and the lead portion is connected to the lead terminal where the electrode wire is exposed. The upper housing and the lower housing are connected and provided in the upper housing, and the lead terminal and the electrode wire are connected between the upper and lower housings so that the upper housing and the lower housing are separably engaged and fixed. The gist is that an engaging portion is provided.

[Operation] The gas detection sensor of the present invention having the above-described configuration engages the lower housing containing the gas detection board and the upper housing containing the lead via a dividable engaging portion.
By fixing, the lead terminal and the electrode wire are connected to ensure conduction between the sensor element and the electrode wire, and an electric signal corresponding to a surrounding gas component emitted from the sensor element and / or its gas concentration is externally provided. Output. Therefore, if the sensor element is arranged in the gas to be measured, the gas component and / or the gas concentration in the gas to be measured is detected.

In the design, the gas detection board design in the lower housing corresponding to the internal combustion engine that generates the gas to be measured and the lead design in the upper housing corresponding to the peripheral equipment outside the internal combustion engine are separated.・ Bring independence.
As a result, not only the degree of freedom of the sensor design, but also one of the gas detection board in the lower housing or the lead portion in the upper housing can be made common and the other can be changed according to the internal combustion engine and its peripheral devices, Its versatility is improved.

Example Next, an example in which the gas detection sensor according to the present invention is applied to an oxygen sensor that detects oxygen concentration will be described with reference to the drawings. 1 is a sectional view of the oxygen sensor of the embodiment, FIG. 2 is an exploded perspective view of an element substrate, FIG. 3 is a sectional view taken along line II in FIG. 1, and FIG. 4 is II-II in FIG. It is a line sectional view. In the description, the composition, manufacturing method, manufacturing procedure, and the like of the oxygen concentration detecting element and the like are well known and do not directly relate to the gist of the present invention, and therefore, detailed description thereof will be omitted.

As shown in FIG. 1, the oxygen sensor 1 has a titania (Ti
A detection unit 7 holding an element substrate 3 having an oxygen concentration detection element (sensor element) 2 composed of an O ₂ ) layer in a metal shell 5 and a union 9 screwed into a male screw of the metal shell 5 to the detection unit 7. It is composed of a detachable lead portion 11.

As shown in FIG. 2, the element substrate 3 of the detecting unit 7 has a first heater pattern 31 for heating the sensor element 2 and a first lead terminal 31a, 31b connected to an end of the heater pattern. An alumina substrate 32, a second alumina substrate 35 on which electrode patterns 33, 34 of the sensor element 2 printed with a thick film of platinum paste and platinum lead terminals 33a, 34a connected to respective pattern ends are formed; A third alumina substrate having an opening 36 at which the tips of the patterns 33 and 34 are exposed.
37 are sintered under a predetermined condition, filled with the openings 36, and are fired on the titania layer, that is, the columnar body formed by firing the sensor element 2 so as to be adhered to the tips of the electrode patterns 33 and 34.

The sintering of the laminated alumina substrates is performed by an alumina cylindrical substrate holder 13 which is air-tightly fixed to the metal shell 5.
The element substrate 3 and the substrate holder 13 are integrated at the same time as firing. Also, platinum lead terminals 31a, 31b, 33a and 3
4a, so that the end is exposed at the end face of each alumina substrate,
Connected to each pattern.

The detecting unit 7 includes, in addition to the element substrate 3 and the cylindrical metal shell 5 for attaching the oxygen sensor 1 to the internal combustion engine, an alumina substrate holder 13 co-fired with the element substrate 3, and a tip of the metal shell 5. A protector 15 and the like that are attached to protect the element substrate 3 are provided, and are assembled as follows.

First, the square hole 13a of the alumina substrate holder 13 before sintering
Then, an alumina element substrate 3 before sintering is inserted so that the end faces thereof substantially coincide with each other.
The protruding side fillet 13b is supplemented with alumina paste, and then the substrate holder 13 and the element substrate 3 are dried at about 150 ° C. The element substrate 3 and the substrate holder 13 may be made of zirconia instead of alumina. In this case,
The supplementary paste is zirconia.

Next, as shown in FIG. 3, platinum electrode portions 17 individually covering the platinum lead terminal portions 31a, 31b, 33a and 34a exposed on the upper end surfaces of the substrate holder 13 and the element substrate 3, respectively.
a, 17b and 19a, 19b are formed by a platinum paste screen printing method or a tampon printing method. That is, the platinum electrode portions 17a and 17b enlarge the platinum lead terminal portions 33a and 34a for outputting the detection signal of the sensor element 2, and the platinum electrode portions 19a and 19b expand the platinum lead terminals connected to the heater pattern 31. The terminal portions 31a and 31b are enlarged. After printing the platinum paste for enlarging the terminals in this manner, the element substrate 3 and the substrate holder 13 on which the platinum paste is printed are integrally and airtightly fired under a sintering condition of 1500 to 1600 ° C. for 2 hours.

Then, the substrate holder 13 integrated with the element substrate 3 is
The substrate holder 1 in which the packings 21 and 23 are arranged vertically is assembled together with the stainless steel packings 21 and 23 into the metal shell 5 and crimped so that the upper end of the metal shell 5 is turned inward.
3 is fixed in the metal shell 5. Thus, the element substrate 3 and the substrate holder 13 are airtightly fixed in the metal shell 5 through the packings 21 and 23. When performing the above-mentioned caulking, talc may be filled between the packing 21 and the substrate holder 13 to further improve the airtightness.

After that, the key 27 is fitted and fixed in the key groove 13c at the upper end of the substrate holder 13, and the stainless steel packing 28 is attached to the shoulder at the upper end of the metal shell 5, so that the detection unit 7 is completed.

As shown in FIGS. 1, 3, and 4, a lead portion 11 detachably attached to the metal shell 5 of the detecting portion 7 by a union 9 is a stainless steel outer cylinder 41 for rotatably holding the union 9 as shown in FIGS. And an alumina electrode holder 43 housed and fixed in the outer cylinder 41, and four electrode wires (shield wires containing magnesia or the like in a range requiring heat resistance) 45a, 45b,
In addition to the pipe 47 and the like fixed to the upper end of the outer cylinder 41 to protect 45c and 45d, electrode pins 49a, 49b, 49c, and 49d, stainless steel or spring steel spring 51, and the like are described below. , Are provided in the electrode holder 43. The pipe 47 is brazed so as to be airtight to the outer cylinder 41 with a brazing material 47a at a projecting portion from the outer cylinder 41.

At the lower end of the electrode holder 43, a fitting hole 43a into which the upper end of the substrate holder 13 is fitted, and a key groove 43b in which the key 27 of the substrate holder 13 is slidable are formed. Further, the electrode holder 43 is provided with each platinum electrode part 1 on the upper end surface of the substrate holder 13 with reference to the key groove 43b.
Four pin storage holes 53 are provided at positions facing 7a, 17b, 19a, and 19b.
And a guide hole communicating with each pin storage hole 53 at the top and bottom.
53a and 53b.

Each of the pin holes 53 has a stainless steel electrode pin.
The terminal tips 49a, 49b, 49c, and 49d protrude from the guide holes 53b into the fitting holes 43a with gold or platinum terminal tips 55 welded to the ends thereof, and are slidably housed therein. Each of these electrode pins
The upper end thereof is constantly urged toward the substrate holder 13 by a spring 51 housed in the pin housing hole 53. The terminal chip 55 may be made of stainless steel plated with gold or platinum.

Then, at the upper end of each of the electrode pins 49a, 49b, 49c, 49d, the above-mentioned electrode wires 45a, 4 wired in the pipe 47 and each guide hole 53a.
The tips of 5b, 45c, and 45d are welded and fixed in correspondence with the respective subscripts, and the lead portion 11 is completed.

Therefore, the key 27 of the substrate holder 13 is aligned with the key groove 43b of the electrode holder 43, the upper end of the substrate holder 13 is fitted into the fitting hole 43a of the electrode holder 43, and the union 9 is screwed into the male screw of the metal shell 5. When the union 9 is rotated together, the substrate holder 13 is attracted to the electrode holder 43 side along the key groove 43b in the fitting hole 43a, and the separately formed detecting unit 7 and lead unit 11 are separated. , With the packing 28 interposed therebetween.

At this time, each platinum electrode portion 17a, 17b, 19a, 19b and each electrode pin 49 facing each other with the key 27 and the key groove 43b as reference positions.
The terminal chips 55 at the tips of a, 49b, 49c, and 49d come into contact with each other. For this reason, the sensor element 2 includes the electrode patterns 33 and 34, the platinum lead terminals 33a and 34a, the platinum electrodes 17a and 17b, and the electrode pins 49c and 49.
The heater pattern 31 is electrically connected to the electrode wires 45c and 45d through the d and the like, and the platinum lead terminal portions 31a and 31b and the platinum electrode portions 19a and 19b.
And the electrode wires 45a, 45b through the electrode pins 49a, 49b and the like.

In this way, the oxygen concentration detected by the sensor element 2 is output as an electric signal through the electrode lines 45c and 45d, and the sensor element 2 is heated by energization of the heater pattern 31 through the electrode lines 45a and 45b, and its temperature characteristic is Is completed.

As described above, the oxygen sensor according to this embodiment includes the sensor element indispensable as the oxygen sensor and the electrode wire for extracting the output of the sensor element, which are separately provided in the detection unit 7 and the lead unit 11 that are independently configured. According to 1, the length of the element substrate 3 and the size and shape of the sensor element 2 itself, that is, the design of the detecting section 7 disposed in the exhaust pipe of the internal combustion engine are independent of the lead section 11 mounted outside the internal combustion engine. Therefore, the degree of freedom in designing not only the detection unit 7 but also the lead unit 11 can be expanded. As a result, since one of the detection unit 7 and the lead unit 11 can be made common and the other can be made to have various shapes, lengths, and the like, restrictions due to the shape of the internal combustion engine in using the sensor are reduced, Its versatility expands.

In addition, if one of the detection unit 7 and the lead unit 11 fails and becomes unusable due to damage to the sensor element 2 or disconnection of the electrode wire, it is sufficient to replace only the failed side. The work and cost required for replacement can be reduced as compared with the case where the whole is replaced. or,
Since the detection unit 7 and the lead unit 11 can be manufactured separately, an assembling process (storage and fixing of the element substrate or platinum electrode wire to the housing made of glass or the like) necessary for manufacturing the conventional oxygen sensor. Can be omitted, and the manufacturing process of the detection unit 7 and the lead unit 11 can be centralized and simplified, so that the manufacturing efficiency can be improved and the cost can be reduced. Since the platinum electrode wire is replaced with the sheath wire, occurrence of disconnection or the like can be suppressed.

Further, when fixing the element substrate 3 to the substrate holder 13, not only these two members but also the supplementary paste have the same composition (one of alumina and zirconia).
The airtightness between the element 13 and the element substrate 3 can be reliably improved.

Alternatively, in the present embodiment, platinum electrode portions 17a, 17b formed by a screen printing method or a tampon printing method of a platinum paste.
By enlarging the platinum lead terminal portions 33a and 34a for outputting the detection signal of the sensor element 2 and the platinum lead terminal portions 31a and 31b connected to the heater pattern 31, the terminal chip contacting each of these platinum electrodes Since each of the electrode pins having 55 is configured to be constantly biased toward the platinum electrode portion by the spring 51, after the assembly of the oxygen sensor 1 is completed,
The reliability of the electrical connection between each platinum electrode portion and each terminal chip is improved. As a result, not only the output of the detection result of the sensor element 2 to the outside but also the heating of the sensor element 2 by the heater pattern 31 can be reliably performed.

In addition, since the constituent members of the oxygen sensor 1 are formed from a stainless steel material and a ceramic material, the heat resistance can be improved.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

For example, without using the union 9, the outer cylinder 41 of the lead portion 11 may be used.
And the metallic shell 5 of the detection unit 7 are directly fixed by screws, or a connector is provided at the tip of a pipe 47 that accommodates the electrode wires 45a, 45b, 45c, and 45d. May be connected.

Effects of the Invention As described above in detail including the embodiments, according to the gas detection sensor of the present invention, the lower housing housing the gas detection board and the upper housing housing the lead portion are separately configured and can be divided. By engaging and fixing the lower housing and the upper housing through a suitable engaging portion, the lead terminals and the electrode wires are connected to ensure conduction between the sensor element and the electrode wires. As a result, a gas detection sensor capable of detecting the surrounding gas component (in the gas to be measured) and / or its gas concentration by the sensor element after the assembly by the engagement portion is completed is provided.

Further, the design of the gas detection board in the lower housing corresponding to the internal combustion engine or the like that generates the gas to be measured and the design of the lead portion in the upper housing corresponding to the peripheral equipment or the like outside the internal combustion engine are separated and independent. For this reason, it is possible not only to increase the degree of freedom of the sensor design, but also to make one of the gas detection board and the lead part common and change the other according to the internal combustion engine and its peripheral devices, etc. Can be planned.

[Brief description of the drawings]

1 is a sectional view of the oxygen sensor of the embodiment, FIG. 2 is an exploded perspective view of an element substrate, FIG. 3 is a sectional view taken along line II in FIG. 1, and FIG. 4 is II-II in FIG. It is a line sectional view. DESCRIPTION OF SYMBOLS 1 ... Oxygen sensor, 2 ... Sensor element, 3 ... Element board, 5 ... Metal shell, 7 ... Detection part, 11 ... Lead part,
13 …… Substrate holder, 17a, 17b, 19a, 19b …… Platinum electrode part, 4
1 ... outer cylinder, 43 ... electrode holder, 45a, 45b, 45c, 45d ... electrode wire, 49a, 49b, 49c, 49d ... electrode pin, 51 ... spring, 55
…… Terminal chip

Continuation of the front page (72) Inventor Toshitaka Matsuura 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Special Ceramics Co., Ltd.

Claims (1)

(57) [Claims] A sensor element for generating an electrical signal corresponding to a surrounding gas component and / or its gas concentration; a gas detection board having a lead terminal connected to the sensor element; A lead portion having an electrode line for outputting an electrical signal of the sensor element to the outside, wherein the lead portion and the gas detection board are stored in a housing. A splittable upper housing and a lower housing, wherein the gas detection board is provided by hermetically housing a ceramic material in the lower housing so that the lead terminals are exposed on the upper housing side; , The electrode wire is provided in the upper housing so as to be opposed to the exposed lead terminal, and provided between the upper and lower housings. Serial gas detection sensor, characterized in that a engagement portion for dividing engaging and fixing the said by connecting the lead terminal and the electrode lines the upper and lower housings.