JPS6124929Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a membrane structure concentration detector with a heater.

As a conventional concentration detector with a membrane structure equipped with a heater, for example, an oxygen concentration detector as shown in FIGS. This heater-equipped membrane structure concentration detector 1 has a metal holder 2 whose tip from the flange 3, that is, the left side of the A-A plane in FIG. It is inserted into the sensor to detect oxygen concentration. Above flange part 3
A hole 4 protrudes from the tip of the hole 4 into which the gas to be measured flows.
A main part of the louver 5 having a heater-equipped film structure concentration detection sensor element part 6 is built-in.
This concentration detection sensor element section 6 is attached to the holder 2 via an alumina insulating tube 7 for holding the sensor, and a ground lead wire 8, a sensor output lead wire 9, and a heater lead wire 10 are drawn out. These lead wires 8 to 10 are covered with alumina powder insulator 1 for fixing.
1. It is installed inside the holder 2 via a Teflon insulating tube 12 and connected to a connector section 13 at the rear end.

As shown in the enlarged detailed view of FIG.
54-164191, etc.), a heater 16 made of platinum wire interposed between a pair of relatively thick alumina substrates 14 and 15, and a thin film laminated sensor section fixed on the upper alumina substrate 14. 17. The sensor part 17 has an inner platinum electrode 18 and a solid electrolyte 1 on an upper alumina substrate 14 with good insulation.
9. Stack the outer platinum electrodes 20 one after another, and form the protective layer 2.
1 is placed over these surfaces. In addition, in order to improve the durability of each lead wire 8 to 10,
Two holes 22, 2 are formed in the upper alumina substrate 14 for the lead wires 8, 9 of the inner electrode 18 and outer electrode 20.
3 and drawn out from between both alumina substrates 14 in parallel with the heater lead wires 10.

In such a configuration, the inner and outer electrodes 18
By applying current between the electrodes 8 and 20 through the lead wires 8 and 9, oxygen ions move between the two electrodes sandwiching the solid electrolyte 19 depending on the direction of the current, and the oxygen generated at the interface The partial pressure is maintained at a constant value by the intrusion of oxygen in the gas to be detected that passes through the protective layer 21 or by the diffusion of internally generated oxygen into the gas to be detected. Therefore, the oxygen concentration in the detected gas is determined based on the electromotive force generated in the solid electrolyte 19 according to the difference between this constant reference oxygen partial pressure and the oxygen partial pressure contained in the detected gas. can be measured. Since the solid electrolyte 19 is activated by the heating action of the sensor section 17 by the heater 16, accurate oxygen concentration measurement can be performed immediately after starting the internal combustion engine at a relatively low temperature.

However, in such a conventional membrane structure concentration detector with a heater, the heater 16 is connected to the relatively thick upper alumina substrate 14 and the lower alumina substrate 1.
5, the distance between the heater layer 16 and the sensor section 17 is large, and therefore the heat of the heater layer 16 is not effectively transferred to the sensor section 17, and both alumina substrates 14, 15 There is a large proportion of heat escaping to the sensor support part 7 through the sensor part 17 due to the heat capacity of the upper alumina substrate 14.
There was a problem in that the temperature response of the sensor was slow, and the gas to be detected escaped to the sensor support part 7 through the through holes 22 and 23 for the lead wires.

This idea was created by focusing on these conventional problems, and consists of stacking a heater layer, an insulating film, an inner platinum electrode layer, a solid electrolyte layer, and an outer platinum electrode layer on a substrate from below in a laminated manner. The present invention aims to solve the above-mentioned problems by constructing a concentration detection sensor element section by sandwiching and fixing each lead wire between a substrate and a fixing member.

This invention will be explained below based on the drawings.

FIGS. 3 to 6 are diagrams showing an embodiment of this invention.

First, to explain the structure, this heater-equipped film structure concentration detection sensor 6 includes a heater layer 16 formed in a laminated manner by printing or vapor deposition on an alumina substrate 31 with good insulation, a thin film insulating layer 32, an inner platinum Electrode 18, solid electrolyte 19, outer platinum electrode 2
0. A small upper substrate 33 having a protective layer 21 and serving as a fixing member for sandwiching and fixing the lead wires 8 to 10 connected to the heater layer 16 and the poles 18 and 20 between the upper surface of the end portion of the alumina substrate 31. have.

To further explain the manufacturing process, the heater section 16 is printed on the alumina substrate 31 (FIG. 6a),
A thin film-like insulating layer 32 is formed thereon, leaving the lead wire connecting portion 34 (FIG. 6b). The insulating layer 32 is formed by plasma spraying an insulating material such as alumina, mullite, or spinel, or by printing or baking a paste of such an insulating material. Further, when performing plasma spraying, a suitable masking is placed over the lead wire connecting portion 34 at the right end of the drawing, and the spraying is carried out only in the area indicated by the broken line in the drawing.

Next, the inner platinum electrode 18 is printed or deposited on the insulating layer 32 in the area indicated by the broken line in FIG. 6c.
At this time, a portion 18a of the electrode 18 is pulled out to the outer end of the lead wire connecting portion 34. This inner platinum electrode 18
A solid electrolyte 19 is printed or deposited to cover the top (FIG. 6d). Further, an outer platinum electrode 20 is printed or deposited on the solid electrolyte 19 in the area indicated by the broken line in FIG. 6e. At this time, a part 20a of the electrode 20 is pulled out to the outer end of the lead wire connecting part 34 and overlapped with one of the drawn parts 16a of the heater 16.

Next, as shown in FIG.
Connect the sensor and heater grounding lead wire 8 to the lead-out part 20a of the outer platinum electrode 20 overlapped with the outer platinum electrode 20, the sensor output lead wire 9 to the lead-out part 18a of the inner platinum electrode 18, and the heater lead wire 9 to the other heater lead-out part 16b. Weld the lead wires 10 for
Connect by gluing or crimping. At this time, the lead wires 8 to 9 are arranged in parallel to each other at approximately equal intervals. In addition, in order to securely fix these lead wires 8 to 10, a small upper insulating substrate 33 is fixed on the lead wire connecting portion 34 of the alumina substrate 31, and the lead wires 8 to 10 are connected to the alumina substrate 31 and the upper substrate 3.
3 (Figure 6g). Note that grooves 35 for inserting the lead wires 8 to 10 are formed in the lower surface of the upper substrate 33.

Finally, a protective layer 21 formed by printing, thermal spraying, or vapor deposition is applied over the entire upper surface (FIG. 6h).

Next, the action will be explained.

When the heater lead wire 18 is energized, the heater 1
6 generates heat, but the heater 16 and the inner platinum electrode 18
Since the insulating layer 32 in between is made into a thin film and has an extremely thin thickness, the temperature of the heater 16 and the sensor part 17 are
The temperature difference between the heaters 16 and 16 is reduced, and the heat from the heater 16 can be effectively used without escaping to other locations. As a result, the time required for the temperature of the sensor section 17 to rise quickly and reach a predetermined temperature at which the concentration of the gas to be detected can be measured is shortened, resulting in the effect that concentration detection with good responsiveness can be achieved. Furthermore, since the insulating layer 32 is formed into a thin film, the manufacturing cost can be reduced and the weight can be reduced compared to the conventional relatively thick upper alumina substrate. Further, since the lead wires 8 to 10 are interposed using the small upper substrate 33 as a fixing member, it is possible to prevent the inconvenience of the gas to be detected escaping to the sensor support portion through the alumina substrate as in the conventional case.

Furthermore, even if a detector is constructed by laminating heater layers and electrode layers on the substrate, the lead wires are clamped and fixed by the fixing member, so the lead wires do not fall off or break, improving durability. .

Note that this invention can also be applied to a membrane structure concentration detector with a heater for purposes other than oxygen concentration detection.

As explained above, according to this idea,
The structure is such that the insulating layer between the heater layer provided on the substrate and the sensor section is made into a thin film, and the lead wires are fixed with a separate fixing member, so that the amount of heat generated by the heater can be used effectively. The effect is that concentration detection can be performed with good responsiveness.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of the conventional device, Fig. 2 is an enlarged detailed perspective view of the main part of Fig. 1, the membrane structure concentration detection sensor element with heater, and Fig. 3 is an embodiment of this invention. FIG. 4 is a sectional view taken along line B-B in FIG. 3, FIG. 5 is a sectional view taken along line C-C in FIG. 4, and FIGS. FIG. 3 is a plan view showing various manufacturing process states of the sensor element section shown in the figure. DESCRIPTION OF SYMBOLS 1...Membrane structure concentration detector with heater, 6...Membrane structure concentration detection sensor element part with heater, 8...Grounding lead wire, 9...Sensor output lead wire, 10...
...Heater lead wire, 16...Heater, 17...
Sensor part, 18... Inner platinum electrode, 19... Solid electrolyte, 20... Outer platinum electrode, 21... Protective layer, 31... Alumina substrate, 32... Thin film insulating layer, 33... Upper substrate, 34 ...Lead wire connection section.

Claims (1)

[Scope of utility model registration request] A thin insulating layer is provided on the heater layer provided on the substrate, and an inner platinum electrode layer, a solid electrolyte layer, and an outer platinum electrode layer are sequentially laminated on the insulating layer, and the leads of the heater layer and electrode layer are formed. A membrane structure concentration detector with a heater, characterized in that a fixing member is provided to clamp and fix the wire between the wire and the substrate.