JPH04178555A - Gas sensor - Google Patents

Abstract

PURPOSE:To electrically connect and fix a gas detector and lead wires simply by aligning the lead portion of the gas detector on the lead wires of a holder, and connecting the lead portion to the lead wires when the gas detector is fixed. CONSTITUTION:A sensor is constituted of a gas detector 10 and a insulating holder 11 made of ceramic and the like and laminated with the detector 10 to hold it. The holder 11 is formed with an alumina plate with the size 20X70X3mm, for example, lead wires 12, 13 made of a good conductor such as platinum are integrally formed on the surface, and protruded projections 14 are provided on part of the lead wires 12, 13. The detector 10 has a gas detection section 10a for detecting gas in it, and a lead section 10b made of platinum and the like and communicated to the detection section 10a is formed on the surface of the detector 10. When the detector 10 is laminated on the holder 11, the lead section 10b is aligned with the projections 14 of the lead wires 12, 13 for connection, then the detector 10 and the holder 11 are electrically connected simply.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gas sensor for measuring gas concentration in an atmosphere.

2. Description of the Related Art A conventional gas sensing body of this type and the structure in which this gas sensing body is mounted are shown in FIGS. 8 and 9.

That is, as shown in the figure, the gas sensing portion 1 is formed on the outer surface of the ceramic insulating tube 2 and includes an electrode 3a.

It is electrically connected to lead wires 4a and 4b via wire 3b. On the other hand, a heater coil 5 is arranged in the internal through hole of the ceramic insulating tube 2, and heats the gas sensing section 1 to a predetermined temperature.

The electrodes 3a, 3b and the heater coil 5 of the gas sensing part 1 are fixedly inserted into the bottom body 6 through their respective lead terminals at terminals 8a, 8b.

It is electrically connected and fixed to 8c and 8d. In addition, the gas sensing section 1, heater coil 5, and lead wires 4a and 4b are
The upper surface of the bottom body 6 made of ceramic or synthetic resin,
It is placed in an internal space formed by a substantially hemispherical protector 7 made of stainless wire mesh or the like, so as to be protected from external mechanical damage and to have good contact with the measurement atmosphere.

Problems to be Solved by the Invention However, in the configuration of the conventional gas sensor described above, the electrical connection between the electrodes 3a, 3b of the gas sensing part I, the lead wires 4a, 4b, and the terminals 8a, 8b is made by using ultrafine platinum on the electrodes 3a, 3b. A step of applying the lead wires 4a, 4b made of wire and fixing them by adhering them with a conductive adhesive, and attaching the lead wires 4 made of the ultrafine platinum wire to the terminals 8a, 8b made of nickel wire.
A process of attaching and welding parts a and 4b was required, making the lead wire connection complicated. That is, the reason why this electrical connection is complicated is that the electrodes 3a and 3b of the gas sensing section 1
This is because it is practically difficult to directly fix the terminals 8a and 8b made of nickel wire to the terminals 8a and 8b.

That is, since the electrodes 3a and 3b of the gas sensing part 1 are made of a precious metal such as platinum mixed with a small amount of glass,
Therefore, it is not possible to weld the terminals 8a and 8b. Therefore, electrical connection is obtained by indirectly using leads m4a and 4b made of ultra-fine platinum wires, but lead wires 4a and 4b are
Welding 4b to the electrodes 3a and 3b on the gas sensing part 1 is difficult in practice for the reasons mentioned above. lead 1iA4a (precious metal-containing glass)
, 4b and the electrodes 3a, 3b were actually fixed. As described above, it takes a lot of time and effort to electrically connect the lead wires 4a and 4b, which poses a problem in that production cannot be increased.

The present invention solves the above problems, and aims to provide a gas sensor in which the electrodes of the gas sensing body, lead wires, and terminals can be easily connected and fixed.

Means for Solving the Problems In order to achieve the above object, the gas sensor of the present invention includes an insulating holder on which a lead wire is formed, and a lead for a gas sensing section on the surface of the holder, which is laminated and held on the holder. a gas sensing body formed with a portion, and electrical conduction and fixation of the gas sensing body are performed by joining a protrusion formed on a lead wire of the holding body and a lead portion of the gas sensing body. It is composed of

According to the above-described structure, when the lead portion of the gas sensing portion formed on the surface of the gas sensing body by laminating the gas sensing body on the insulating holder is aligned with the lead wire of the insulating holder, Since they are joined by the protrusions formed on the lead wires, electrical continuity can be easily achieved by simply laminating the two, and the joints can be sintered through the protrusions by firing, or the two can be bonded together. It can be easily held by pressing it.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

1 and 2 are an exploded perspective view and a front (longitudinal direction) sectional view of a gas sensor according to a first embodiment.

As shown in the figure, the gas sensor includes a gas sensing body 10 and an insulating holder 11 made of ceramic or the like that holds the gas sensing body 10 in a stacked manner. The holder 11 is, for example, an alumina plate with dimensions of 20 x 70 x 3 sheets, and lead wires 12 and 13 made of a good conductor such as platinum are integrally formed on the surface, and a portion of the lead wires 12 and 13 is provided with a protrusion. It has 14.

Further, the gas sensing body 10 has a gas sensing part 10a for gas sensing inside, and the gas sensing part 10a is provided on the surface of the gas sensing body 10.
A lead portion 10b made of platinum or the like is formed to be electrically connected to the lead portion 10b.

When stacking the gas sensing body 10 on the holder 11, the gas sensing body 10 and the holder 11 can be easily stacked by aligning and joining the lead portions 10b to the protrusions 14 of the lead wires 12 and 13.
It is possible to obtain electrical continuity between the two. After lamination, they can be easily fixed by firing and sintering the joint, or by mechanically pressing the two together. Note that the protrusion 14
may be formed of a different material such as a silver-baladium alloy on the lead wire material 12.13.

With the above configuration, the conductive fixing of the gas sensing element 10 does not require conventional welding or adhesion with conductive adhesive, so there is no need for labor during production, and the joints do not require sintering or mechanical pressure welding. Reliable electrical continuity can be obtained and quality can be stabilized.

Next, FIGS. 3 and 4 regarding the second embodiment.

This will be explained based on FIGS. 5 and 6. The difference from the first embodiment is that the gas sensing element is housed in the recess of the holder, the lid is placed on top of the gas sensing element, and the lid and holder are sandwiched between the holder and the lid. The point is that the gas sensing element can be electrically connected through the lead wire on the outer surface of the body.

That is, as shown in FIG. 3, FIG. 4, and FIG. 5, the holder 21 made of an alumina plate or the like has a recess 21a on the upper surface side for housing the gas sensing element 20, and a recess 21a on the bottom surface of the recess 21a. A gas outlet 21b having a penetrating shape and a gas inlet 21c communicating with the front surface of the holder 21 are provided at the front of the recess 21a. The gas sensing body 20 is fitted into the recess 21a of the holder 21, and the holder 21 is
A lid body 22 made of an alumina plate or the like that matches the upper surface is placed and fixed to the upper surface of the holder 21 by firing or the like via a bonding agent 21d or the like.

The gas sensing body 20 has lead parts 20b, 20c made of platinum or the like of the gas sensing part 20a and conductive parts 20e, 20f made of the same material as the heating part 20d on the upper and lower surfaces.
When 0 is placed in the recess 21a, the lead portion 20b on the lower surface is electrically connected to a lead wire 23 made of platinum or the like formed on the lower surface of the holder 21. Also, the gas sensor 2
Lead portion 20c and conductive portions 20c, 20r on the top surface of
are electrically connected to lead wires 22a, 22b, and 22c formed on the top surface of the lid 22 and made of platinum or the like.

This gas sensing body 20 and both lead wires 23 and 22
Electrical connections with a, 22b, and 22c are made by protrusions 25 provided on the holder 21 and the lid 22, as shown in FIG. That is, the projection piece 25 is made of a good conductor such as a silver-baladium alloy embedded in the through hole of the holder 21 and the lid 22, and one end is connected to the holder 21 and the lid 22.
Each lead wire 23 and 22 a + 2 on the outer surface of 2
2 b + 22 c, and the other end protrudes from the bottom of the recess of the holder 21 and the inner surface of the lid 22 to form a protrusion 24 .
is formed. The protrusions 24 are connected to the lead portions 20b, 20c and the conductive portion 20 of the gas sensing body 20, respectively.
e, 2Of to complete electrical continuity.

The lead wires 23.degree. 22a, 22b, 22c are formed on the holder 21 and the lid 22 by, for example, a thick film printing method, and the connection between the lead wires 23.22a, 22b, 22c and the projection piece 25 is performed by baking. It may be sintered by Moreover, if the protrusion 24 is bonded to the lead parts 20b, 20c and the conductive parts 20e, 20f of the gas sensing body 20 by firing with a paste made of silver-baladium alloy interposed therebetween, a stronger conductive fixation can be achieved. Furthermore, the above-mentioned holding body 21 and lid body 22
Although the dimensions of the holding body 21 are approximately 20 x 70 x 3 mm, and the recess 21a is provided in the holder 21, the structure may be reversed by providing the recess 21a in the lid 22. In addition, the heating section 2 of the gas sensing body 20
0d, the holding body 21 may be provided on the lid body 22 side.

In the gas sensor in which the gas sensing body 20 is set in the holder 21 having the above configuration, solid gas of the gas sensor flows in from the gas inlet 21c, comes into contact with the gas sensing body 20, and then flows out from the gas outlet 21b. .

At this time, a current change occurs in the gas sensing section 20a, and the resulting signal is outputted from the lead wires 22a and 23 via the protruding piece 25 to a control section (not shown) connected thereto.

In this way, the gas sensing body 20 is held between the holding body 21 and the lid body 22, and the gas sensing body 20 is easily made electrically conductive by being electrically connected to each holding part via the protruding part 24 formed by the protruding piece 25. can be pulled out.

Next, the gas sensing body 20 described in the second embodiment will be explained based on FIG. 7.

That is, this gas sensor 20 is a limiting current type oxygen sensor, and has a solid electrolyte plate 2OA exhibiting oxygen ion conductivity.
Electrode films 20B and 20C (20C is not shown) are formed on both sides. A spiral spacer 20D that surrounds the electrode film 20B and has a starting end and a terminal end spaced apart from each other is disposed on one surface of the solid electrolyte plate 2OA, and furthermore, a sealing plate 2
0E is placed above it. The spiral diffusion hole (hereinafter referred to as diffusion hole) 20F is the spiral spacer 20F.
D opposing partition walls, solid electrolyte plate 20A, and seal plate 2
It is formed by a spiral space surrounded by 0E, and oxygen diffuses into the electrode film 20B via the space. A heating portion 20d is formed on the upper surface of the seal plate 20E, and heats the solid electrolyte plate 2OA to improve oxygen ion conduction.

In the above configuration, a predetermined power is applied to the heating section 20d via the conductive sections 20e and 2Of (not shown), and the fixed electrolyte plate 20A is heated to a predetermined temperature via the heating section 20d. On the other hand, the solid electrolyte plate 2OA (in this case, the electrode films 20B and
20C (not shown)) is also applied with a predetermined voltage. Then, oxygen in the air flows in through the diffusion hole 20F,
Furthermore, a current using oxygen ions as carriers flows from the anode electrode film 20C (not shown) toward the cathode electrode film 20B. Oxygen moves within the solid electrolyte plate 2OA due to this oxygen pumping action, but since the inflow of oxygen molecules is restricted by the diffusion holes 20F, a saturation current (referred to as a limiting current) is generated depending on the oxygen concentration. Oxygen concentration can be determined by measuring this limiting current value.

Next, the effect will be explained using a specific experimental example. The gas sensor 20 is the aforementioned limiting current type oxygen sensor,
As the solid electrolyte plate 2OA shown in the figure, Zr Ox ・Y
s 0s (YzOs 8 m 01% addition), platinum as the electrode film 2OB/20C, glass as the spiral spacer 20D (the thermal expansion coefficient is approximately the same as ZrO□/Y2O, and heat-resistant particles with a predetermined particle size). ), forsterite was used as the seal plate 20E, and platinum was used as the heating part 20d. The manufacturing method will be explained. First, the electrode film 20
B.20C (not shown) was printed on the upper and lower surfaces of the solid electrolyte plate 2OA, and the heating part 20d was printed on the seal plate 21 using a thick film printing technique, and then baked. Next, the solid electrolyte plate 20A and the seal plate 20E are stacked on the upper and lower surfaces of the spiral spacer 20D and heated and melted.
A diffusion hole 22 was formed between the OA, the spiral spacer 20D, and the seal plate 20E. And the lead part 20c (
20b (not shown) and a conductive portion 20c (20f not shown) were extended to complete the gas sensing body 20. The finished product was manufactured with dimensions of 10 x 10 x O and 9 m, and this gas sensing body 20 was mounted as in the second embodiment described above, and a power of 2.7 W was applied to the heating section 20d to heat the gas. The sensor 20 was maintained at about 450°C. Furthermore, when a voltage of 1.3μ was applied to the gas sensor 20, the voltage was 190 μA (
A limiting current of 20% oxygen was obtained.

As described above, the oxygen diffusion hole 20F is connected to the spiral spacer 20.
By forming the diffusion hole 20F in a spiral shape on the solid electrolyte plate 2OA using D, the diffusion hole 20F can be made longer along the surface. Moreover, the solid electrolyte plate 2OA and the seal plate 20E are stacked on the upper and lower surfaces of the spiral spacer 20D, and the necessary electrodes 2
0B, 20C, heating section 20d and these lead sections 2
0B, 20C and conductive parts 20e, 20f can be easily formed by thick film printing technology and baking.

Therefore, the gas sensing body 2 of the limiting current type oxygen sensor has good gas sensing intensity even though it is small and is inexpensive to manufacture.
0 can be provided.

Effects of the Invention As is clear from the above explanation, the gas sensor of the present invention has the following advantages:
The device includes an insulating holder having a lead wire formed on its surface, and a gas sensing body laminated to the holder and having a lead portion of a gas sensing portion formed on its surface, and electrically conductive and fixing the gas sensing body. Since the structure is such that the protrusion formed on the lead wire of the holder is joined to the lead part of the gas sensing element, the lead part of the gas sensing element is aligned on the glued wire of the holder, and the gas sensing When the body is fixed, the parts formed on the lead wire can be used for joining.

Therefore, electrical continuity and fixation between the gas sensing body and the holding body can be easily achieved simply by laminating the gas sensing body and the holding body.

In addition, by using the gas sensor as a limiting current type oxygen sensor and forming a spiral diffusion hole by interposing a spiral spacer between the oxygen ion conductive solid electrolyte plate and the seal plate, the diffusion hole is connected to the solid electrolyte plate. It can be lengthened along the surface,
Moreover, these laminated connections and the formation of electrodes, heating parts, lead parts, and conductive parts on the surfaces of solid electrolyte plates and seal plates can be easily made using thick film printing technology and baking. Therefore, even with a small size, it is possible to achieve good sensing performance and low manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a gas sensor according to a first embodiment of the present invention, FIG. 2 is a front cross-sectional view taken in the longitudinal direction of FIG. 1 of the first embodiment, and FIG. 4 is an exploded perspective view of the gas sensor of the second embodiment, FIG. 5 is an exploded perspective view of the gas sensor of the second embodiment, and FIG. 5 is an exploded perspective view of the gas sensor of the second embodiment.
FIG. 6 is a partial sectional view of the main part showing the connection between the gas sensing element and the lead wire of the second embodiment, and FIG.
The figure is a partially cutaway perspective view of a gas sensing body of an embodiment of the same gas sensor, FIG. 8 is a perspective view of a conventional gas sensing body, and FIG. 9 is a perspective view of the same gas sensor. 10, 20... Gas sensing body, 11.21...
...Holding body, 12°13.22a, 22b, 22c,
23-Lead wire, 10a. 20a...Gas sensing section, 10b, 20
b, 20 c...Lead part, 14.24.
...Protrusion, 2OA...Solid electrolyte plate,
20D...Spiral spacer, 20E...
・Seal plate, 20F...Spiral diffusion hole. Name of agent: Patent attorney Akira Okaji and two others 10-
Gas Pond Chitai I Mountain - Tsu Harbor Chishu 1 Ob - Reed Shu 11 - I Mug Holding Body 2nd Figure 20 - Gas Detection Hall ↓ Figure 5 Book - Cutting Zhong Figure 6 Figure 20A - 11 Group ? @-Spiral type or pacer 20E---Seal plate 20F-One spiral diffusion hole Figure 7 N00 Figure 8

Claims (2)

[Claims] (1) An insulating holder with a lead wire formed on its surface,
a gas sensing body having a lead portion of a gas sensing portion formed on the surface of the gas sensing body to be laminated and held on the holding body, and a protrusion formed on the lead wire of the holding body for electrically conducting and fixing the gas sensing body; A gas sensor configured to operate by bonding to a lead portion of the gas sensing body. (2) The gas sensor is a limiting current type oxygen sensor in which a spiral diffusion hole is formed by interposing a spiral spacer between an oxygen ion conductive solid electrolyte plate and a seal plate.
1) Gas sensor described.