JPH0612527Y2 - Oxygen sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an oxygen sensor, and more particularly, to a sensor element portion provided at a tip portion of a substrate, which is mounted on, for example, an exhaust pipe of an internal combustion engine, The present invention relates to an oxygen sensor for measuring the oxygen concentration in exhaust gas which is closely related to the air-fuel ratio of the air-fuel mixture supplied to the air.

<Prior Art> As such an oxygen sensor, there is a conventional one as shown in FIG. 5 (see JP-A-62-80552, etc.).

In the oxygen sensor 1, the sensor element unit 3 is provided at the tip of the substrate 2. In this sensor element part 3, for example, platinum electrodes are formed on the inner and outer surfaces of an oxygen ion conductive solid electrolyte, and electrodes on the outer surface contacted with a gas to be detected such as engine exhaust and an inner surface contacted with the atmosphere. The oxygen concentration of the gas to be detected is detected by an electromotive force generated between the electrode and the electrode.

The substrate 2 has an intermediate portion fitted and fixed to an insulator 4, and the insulator 4 is provided with a male screw 5a for fixing the oxygen sensor 1 to a detected portion (for example, an exhaust pipe wall of an internal combustion engine). The holder 5 is fitted and held.

Further, a cap 6 that covers the sensor element portion 3 that is provided so as to project from the tip of the holder 5 is caulked and fixed to the outer periphery of the tip of the holder 5, and the gas to be detected enters and exits through a slit 6 a formed in the cap 6. To do.

On the outer periphery of the holder 5 on the base end side, the tip portions of a cylindrical outer case 7 and inner case 8 are fixed by swaging.
As shown in the figure, talc 9 and graphite 10 which are powders are placed in a space surrounded by the outer circumference of the base end side of the substrate 2 and the inner circumference of the holder 5 and the inner case 8 with the sensor element portion 3 facing downward. The washer 20 is inserted in the lower end surface of the spacer 11 having the through-hole 11a having a rectangular cross section through which the substrate 2 is inserted, and the inner case 8 having an inner diameter larger than the maximum diameter of the substrate 2 is provided on the upper end surface. A washer (21) whose inner peripheral surface does not contact the substrate (2) even if it is maximally eccentric with respect to the substrate (2) is interposed. And this spacer 11
By pressing downward in the figure, the talc 9 and the graphite 10 below the spacer 11 are pressed and the base end portion of the substrate 2 surrounded by the talc 9 and the graphite 10 is clamped and fixed to the outer periphery of the substrate 2. To ensure the airtightness of.

Furthermore, after press-fitting the talc 9 and the graphite 10, the inner case 8 at the portion where the upper end surface of the washer 21 is located is swaged inward to tighten the inner case 8. Press washer 21
Is prevented from being displaced upward, and in such a state, the graphite 10 covering portion of the inner case 8 is swaged inward and squeezed to press the graphite 10 toward the surface of the substrate 2, It is designed to be more airtight.

When the board 2 is airtightly held and fixed in this way, the connector insulator 12 is inserted into the outer case 7 through the upper end opening, and the connector terminal is placed in the inner space of the connector insulator 12.
13 is inserted, and the output terminal portion exposed on the end surface of the substrate 2 and the connector terminal 13 are pressed into contact with each other to output the output.
I will take it out through.

The base end side of the outer case 7 is assembled by incorporating the talc 9, the graphite 10, the connector insulator 12, etc., and then crimped and squeezed, and the disc spring 14 is interposed between the throttle portion and the end face of the connector insulator 12. By doing so, the connector insulator 12 is pressed toward the holder 5 side, and the connector insulator 12 is sandwiched between the crimped portion on the upper surface of the washer 21 and the disc spring 14. Also,
Reference numeral 15 is a rubber bush, and a lead wire 16 connected to the connector terminal 13 is conducted through the rubber bush 15.

<Problems to be solved by the invention> By the way, in the oxygen sensor 1 having such a configuration, the connector insulator 12 is inserted into the outer case 7 from the upper end opening, and the connector terminal is provided in the inner space of the connector insulator 12.
When pressing 13 together, the board 2 tilts and the connector insulator 12
Sometimes interfered with and cracked.

As shown in FIG. 6, when the connector insulator 12 is inserted, the portion 31 of the caulking portion 30 that comes into contact with the lower end 12a of the connector insulator 12 is not completely bent and has a curvature, so that it is pushed down. This is because the connector insulator 12 tilts and a load is applied when the connector insulator 12 is tilted, which causes the yield to deteriorate.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent the connector insulator from tilting when the connector insulator is inserted and to prevent the substrate from cracking when the oxygen sensor is assembled.

<Means for Solving the Problems> Therefore, in the present invention, a through hole is formed for penetrating the substrate with a gap, and both ends of the spacer and the connector insulator are formed at right angles to the substrate longitudinal direction. A positioning member, which is formed in parallel planes in contact with each other and has a peripheral groove at the center of the outer peripheral surface, is interposed between the spacer and the connector insulator, and the tubular case is added at the peripheral groove portion of the positioning member. The spacer and the connector insulator are positioned and fixed by tightening and squeezing.

<Operation> When the positioning member is thus interposed between the spacer and the connector insulator and the circumferential groove portion of the positioning member is fixed by caulking so as to integrally fix the positioning member and the spacer, the connector is formed. When the insulator is inserted, both end surfaces of the positioning member come into contact with the respective end surfaces of the spacer and the connector insulator, and as a result, the spacer and the connector insulator are positioned and attached so that the respective end surfaces are parallel to each other. This prevents the connector insulator from tilting,
Therefore, cracking of the substrate can be prevented.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.
The same elements as those in the conventional example shown in FIGS. 5 and 6 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, a substrate 2 having a sensor element portion 3 at the tip thereof
Is fitted and fixed to the insulator 4 whose middle portion is fitted and held in the holder 5, and the distal ends of the cylindrical outer case 7 and inner case 8 are caulked and fixed to the outer periphery of the holder 5 on the base end side. As shown in the figure, the substrate 2 is placed with the sensor element portion 3 facing downward (described at the position shown in the drawing, and the same applies hereinafter).
After talc 9 and graphite 10, which are powders, are placed in this order in a space surrounded by the outer circumference of the base end side of the holder and the inner circumference of the holder 5 and the inner case 8, and further a washer 20 and a spacer 11 are interposed, A positioning member 40 having a shape as shown in FIGS. 2 and 3 is provided on the upper end surface 11b of the spacer 11.

Furthermore, after the talc 9 and the graphite 10 are press-fitted, the inner case 8 of the circumferential groove portion 40f of the positioning member 40 is swaged inwardly and squeezed to fix the positioning member 40,
In this state, the graphite 10 covering portion of the inner case 8 is swaged inward and squeezed to press the graphite 10 against the surface of the substrate 2 to further enhance the airtightness of the substrate 2.

When the board 2 is airtightly held and fixed in this way, the connector insulator 12 is inserted into the outer case 7 from the upper end opening so that one end face 12a of the connector insulator 12 contacts the one end face 40e of the positioning member 40. The connector terminal 13 is inserted into the inner space, and the output terminal portion exposed on the end face of the substrate 2 and the connector terminal 13 are brought into pressure contact with each other so that the output is taken out through the connector terminal 13.

The base end side of the outer case 7 is assembled by incorporating the talc 9, the graphite 10, the connector insulator 12, etc., and then crimped and squeezed, and the disc spring 14 is interposed between the throttle portion and the end face of the connector insulator 12. By doing so, the connector insulator 12 is pressed toward the holder 5, and the connector insulator 12 is sandwiched between the one end surface 40e of the positioning member 40 and the disc spring 14.

The positioning member 40 is made of, for example, stainless steel, and is a surface that contacts the upper end surface 11b of the spacer 11.
It is a cylindrical positioning member having a flange portion 40a having 40d and a flange portion 40b having a surface 40e in contact with the lower end surface 12a of the connector insulator 12, and is a substrate 2 provided on the spacer 11.
Has a through hole 40c that is sufficiently larger than the through hole 11a through which the
The parallelism is maintained between one end surface 40e of 40b, and this parallel surface is formed parallel to the surface of the spacer 11 and the connector insulator 12 at right angles to the longitudinal direction of the substrate 2, and the flange portion The 40a and the flange portion 40b have a thickness.

According to this structure, the inner case 8 of the circumferential groove portion 40f of the positioning member 40 is swaged inward as shown in FIG. 4 to squeeze, the substrate 2 is airtightly held and fixed, and the connector insulator 12
When the connector is inserted, the connector insulator (12) can be prevented from tilting without coming into contact with the portion (31) where the caulking portion (30) has a curvature, and the load does not cause cracking or the like.

<Effects of the Invention> As described above, according to the present invention, it is possible to prevent the connector insulator from tilting when the connector insulator is inserted after the tubular case is caulked, and to prevent the substrate from cracking when the oxygen sensor is assembled. The effect is that it can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of an oxygen sensor showing an embodiment of the present invention,
2 is a sectional view showing a positioning member in the above embodiment, FIG. 3 is a perspective view thereof, FIG. 4 is a partially enlarged view showing the crimped portion, and FIG. 5 is a sectional view showing a conventional oxygen sensor. ,
FIG. 6 is a diagram (a sectional view taken along the line AA ′ in FIG. 5) for explaining the problems of the conventional oxygen sensor. 1 ... Oxygen sensor, 2 ... Substrate, 3 ... Sensor element part, 4 ... Insulator, 5 ... Holder, 8 ... Inner case, 9 ... Talc, 10
… Graphite, 11… Spacers, 20 washers, 40… Positioning members

Claims (1)

[Scope of utility model registration request] 1. An inner circumference of a cylindrical case, wherein a middle portion of a substrate having a sensor element portion for detecting oxygen concentration at a tip portion is fitted and held in a holder, and is fitted and fixed to a base end side outer circumference of the holder. The powder introduced into the space surrounded by the substrate and the outer circumference of the base end side of the substrate is press-fitted toward the holder through the spacer inserted through the substrate and fitted into the cylindrical case, and the tip side of the spacer is inserted. By clamping and squeezing the substrate, the substrate is clamped and fixed in the tubular case through the powder, and the substrate is provided between the inner periphery of the tubular case and the substrate on the base end side of the spacer. An oxygen sensor having a connector terminal that press-contacts to take out an output to the outside and a connector insulator that holds the terminal, wherein an oxygen sensor is provided with a through hole that penetrates the substrate with a gap and both ends are a spacer and a connector insulator. At right angles to the substrate longitudinal direction A positioning member, which is formed in a parallel plane that abuts each of the formed end faces and has a circumferential groove in the central portion of the outer peripheral surface, is interposed between the spacer and the connector insulator, and the tubular case is provided with the positioning member. An oxygen sensor characterized in that the spacer and the connector insulator are positioned and fixed by caulking and squeezing in the peripheral groove portion of the.