JPS5852525Y2 - oxygen concentration detector - Google Patents

Description

[Detailed description of the invention] The present invention relates to an oxygen concentration detector using a crucible-shaped oxygen ion-conducting solid electrolyte tube. This detector uses gaseous oxygen that is in contact with the electrodes on the inner and outer surfaces of the solid electrolyte tube. A voltage is generated based on the concentration difference, and this is used to detect the oxygen concentration of the exhaust gas.

In this case, if the exhaust gas that is in contact with the outer surface of the solid electrolyte tube mixes with the air that is in contact with the inner surface, malfunctions occur.

Therefore, it is necessary to maintain airtightness so that exhaust gas does not enter the inner hole.

The present invention relates to this airtight structure and a structure for taking out the inner electrode.

A conventional example will be explained with reference to FIG.

A sealing member 5 is brazed with a brazing material 4 on the metallized portion of the inner hole entrance of the solid electrolyte tube 1 by baking the platinum paste to maintain airtightness.

Then, an alumina insulator 6.8, a coil spring Tll, a silicone rubber 9 for preventing air gas from leaking out of the detector, and a metal ring 10 are arranged as shown in Fig. 1, and the casing 12 is tightened at the upper part to form a solid electrolyte. Fix tube 1.

The outer surface electrode 2 is electrically connected to the element receiving material 14 at the shoulder portion of the solid electrolyte tube 1, and the inner surface electrode 3 is electrically electrically connected to the metallized portion and to the current collector tube 11 from the 10-piece portion.

In addition, the flange 13, the casing 12, the element receiving material 14,
Then, the current collector tube 11 and the seal member 5 are both joined by brazing material.

However, there are many factors that affect the brazing material, and there is a strong possibility that the yield will be poor in this respect.

In addition, the baked layer of platinum paste at the entrance of the solid electrolyte tube inner hole requires a certain thickness due to the brazing material, which has the disadvantage of increasing the cost of one metallization.

The present invention has been devised to eliminate the above-mentioned drawbacks. An embodiment of the present invention is shown in FIGS. 2 and 3.

A fourth tube is installed at the stepped inner hole entrance of the crucible-shaped solid electrolyte tube 21.
Graphite 24 formed into a ring shape as shown in the figure
, a collar-shaped current collector terminal 21 , a current collector tube 32 , and a compression ring 2
Assemble 5 and press-fit it.

Then, distribute power to the alumina insulator 26, 29, coil spring 28, and silicone rubber 30° 31 as shown in the diagram.
Tighten the casing 33.

In this way, spring pressure is constantly applied to the graphite 24 portion, thereby maintaining airtightness.

The outer electrode 22 is connected to the casing 3 at the shoulder of the solid electrolyte tube 21.
3, conduction is established between the inner surface electrode 23, the press-fitted current collector terminal 27, and then the current collector tube 32.

In addition, the flange 34, the casing 33, the current collector tube 32, and the current collector terminal 27. All of the compression rings 25 are joined by brazing.

By doing this, the factors that affect airtightness are reduced and the yield is improved.

Then, a platinum paste baking layer for metallizing is unnecessary, and the cost is reduced.

The collector tube is fixed by press-fitting the collar-shaped current collector terminal attached to the current collector tube into the inner hole of the solid electrolyte tube, making assembly easy. Since conduction is established, the reliability of the conduction between the inner surface electrode and the current collector tube is improved.

At the same time, it prevents the formed graphite from flowing into the inner hole of the solid electrolyte tube due to vibration etc. and adversely affecting airtightness and electrical contact, and at the same time, the flow of graphite causes the button to flow into the inner hole of the solid electrolyte tube and oxidizes the graphite at high temperature. It is possible to prevent malfunctions caused by gas generated from the oxygen concentration sensor and realize a highly reliable oxygen concentration detector.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional oxygen concentration detector;
The figure is a cross-sectional view showing one embodiment of the oxygen concentration detector according to the present invention, FIG. 3 is an enlarged cross-sectional view of the main part, and FIG. 4 is a cross-sectional view of the main part before press-fitting. 21... Solid electrolyte tube, 22... External electrode, 23... Inner electrode, 24... Graphite, 2T... Current collector terminal , 28...
...Coil spring, 32...Current tube.

Claims (1)

[Scope of utility model registration request] In a detector for detecting the oxygen concentration contained in the exhaust gas of an internal combustion engine using an oxygen ion conductive solid electrolyte tube equipped with electrodes on the inner and outer surfaces of the crucible-shaped solid electrolyte tube, a Graphite is arranged, crushed, and constantly pressurized by a spring to prevent the exhaust gas from outside the solid electrolyte tube from flowing into the inner hole, and to make electrical contact with the inner electrode and to prevent air from flowing into the inner hole. Attach a collar-shaped current collector terminal to the end of the current collector tube that will serve as the inlet, and press-fit it into the inner hole of the solid electrolyte to fix the current collector tube. An oxygen concentration detector characterized in that it is configured to prevent outflow.