JPH0792134A - Oxygen sensor - Google Patents

Abstract

PURPOSE:To provide an oxygen sensor having a connection terminal with electrode for improving electrical connection between a lead wire and an oxygen detection element. CONSTITUTION:The oxygen sensor 10 comprises an oxygen detection element 20 having inner and outer electrodes 22, 23 arranged in a solid electrolyte. The inner and outer electrodes 22, 23 are held by the resiliency of first and second metal plate terminals 31, 32 connected with lead wires 121, 122, respectively. The plate terminals 31, 32 are provided with a recess or a protrusion and the solid electrolyte 21 is provided with a protrusion or groove engaging therewith thus inhibiting the movement of the plate terminals 31, 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen sensor, for example, an oxygen sensor for detecting an air-fuel ratio of an internal combustion engine such as an automobile.

[0002]

2. Description of the Related Art If the air-fuel ratio of an internal combustion engine of a vehicle is not appropriate,
It causes energy (fuel) loss and air pollution. Therefore, the oxygen sensor is used to detect the air-fuel ratio. The oxygen sensor comprises an electrochemical cell in which electrodes are provided on both sides of a solid electrolyte which is an oxygen ion conductor. Then, the exhaust gas is introduced into one of the electrodes, and the atmosphere is introduced into the other, and the air-fuel ratio of the internal combustion engine is detected from the potential difference between the electrodes caused by the difference in oxygen concentration between the two.

In order to generate oxygen ion conduction in the above solid electrolyte, a high temperature (about 650 ° C. or higher) is required.
Is required, and the heater is used to heat the cell. As shown in FIG. 15, the oxygen sensor 90 has an oxygen detection element 91 that forms an electrochemical cell and a housing 92 that houses the oxygen detection element 91.

The housing 92 has a flange 93 substantially in the center thereof.
1 has a body 93, an exhaust cover 94 inserted into the exhaust passage below the body 93, and an atmosphere cover 95 in contact with the atmosphere above the body 93. . The exhaust cover 94 has an inner cover 941 and an outer cover 942 made of stainless steel, and both covers 941 and 942 are provided with exhaust ports 943 and 944.

On the other hand, the atmosphere cover 95 includes a main cover 951 attached to the body 93 and the main cover 95.
1 has a sub-cover 952 which covers the rear end portion thereof, and each of the covers 951 and 952 is provided with an atmospheric air intake (not shown). The oxygen detecting element 91 is sandwiched by the body portion 93 via the insulating member 932.

The internal electrode 911 of the oxygen sensing element 91 is also used.
The plate electrodes 961 and 962 made of metal and sandwiching the external electrodes 912 are connected to the external electrodes 912. The plate-shaped terminals 961 and 962 are connected to output lead wires 971 and 972.

That is, the plate terminals 961 and 962 are
As shown in FIGS. 16 and 17, band-shaped terminal pieces 963, 9
64 project from the contact pieces 965 and 966. As shown in FIG. 15, the terminal pieces 963 and 964 have one ends 985 and 986 of connectors 981 and 982 whose other ends 983 and 984 are connected to lead wires 971 and 972.
It is connected to the.

The plate-shaped terminals 961 and 962 are formed by transforming an inverted T-shaped metal plate shown in FIG. 17 into a cylindrical shape as shown in FIG. 18 and forming an internal electrode 911 or an external electrode 912 as shown in FIG. Hold it. Then, due to the elastic force (spring action) of the metal plate, the plate-shaped terminals 961 and 962 and the internal electrode 911
Alternatively, an appropriate contact pressure is established with the external electrode 912.

On the other hand, lead wires 971, 97 shown in FIG.
Since a pulling force acting in the axial direction of the oxygen sensor 90 may act on the connector 2, the connector 98 is left in this state.
The plate-shaped terminals 961 and 962 may be pulled via 1,982 and slide in the axial direction. In order to prevent this, as shown in FIG. 15, a stopper 9 sandwiched between rubber bushes 991 and 992 is provided at the end of the oxygen sensor 90.
93 is provided. The stopper 993 is the connector 9
81, 982 are prevented from moving, and are made of a resin material for maintaining insulation between the lead wires 971, 972.

Reference numeral 973 in FIG. 15 is a heater wire for heating the oxygen detecting element 91. The oxygen sensor 90 has an exhaust cover 94 inserted into the exhaust passage and is fixed to the exhaust passage by a flange 931.

[0011]

However, the conventional oxygen sensor 90 has the following problems. That is, the oxygen sensor 90 is mounted in the exhaust passage having a high temperature, and the oxygen detecting element 91 is heated to a high temperature by the heater. Therefore, there is a problem that the deterioration of the resin stopper 993 is fast.

When the stopper 993 deteriorates and is damaged, the plate terminals 961 and 962 move in the axial direction, and the electrodes 911 and 961 are moved.
912 causes a poor contact with the oxygen sensor 90.
Will not work. In view of the problems of the conventional oxygen sensor, the present invention provides an oxygen sensor that can stably secure electrical connection between a lead wire and an oxygen detection element without using a resin member that is susceptible to heat. Is what you are trying to do.

[0013]

According to the present invention, an oxygen detecting element for obtaining an output corresponding to an oxygen concentration, a housing for accommodating the oxygen detecting element and mounted in an exhaust gas passage, and the oxygen detecting element are connected in the housing. An oxygen sensor having a lead wire for taking out an output drawn from an end portion of a housing, wherein the oxygen detecting element is a solid electrolyte, an internal electrode provided on an inner peripheral side of the solid electrolyte, and an outer electrode on an outer peripheral side. It has an external electrode provided and a pair of plate-shaped terminals for sandwiching the internal electrode and the external electrode by the bending elastic force of a metal plate, and the plate-shaped terminal is for engaging with the solid electrolyte. The solid electrolyte is provided with a concave portion or a convex portion, while the solid electrolyte is provided with a groove or a raised portion that engages with the concave portion or the convex portion and suppresses the axial movement of the plate-like terminal. Plate terminals are connected to the above lead wires Lying in the oxygen sensor, characterized in that.

What is most noticeable in the present invention is that the plate-shaped terminal is provided with a concave portion or a convex portion, while the solid electrolyte is engaged with the concave portion or the convex portion to prevent the plate-shaped terminal from moving in the axial direction. That is, the suppressing groove or the rising portion is provided. The groove of the solid electrolyte is engaged with the concave portion of the plate terminal (recess in the axial direction), and the raised portion of the solid electrolyte is engaged with the convex portion of the plate terminal (convex in the radial direction). That is, the concave portion and the groove form an engaging pair, and the convex portion and the descending portion form an engaging pair.

The plate-shaped terminal may be provided with both the concave portion and the convex portion, and the solid electrolyte may be provided with both the groove portion and the raised portion. Further, each of the above-mentioned engaging pairs is only required to restrain the movement of the plate-shaped terminal in the axial direction, and therefore it is not necessary to restrain the movement of the plate-shaped terminal along the outer periphery of the solid electrolyte.

The plate-like terminal holds the electrode by the bending elastic force of the metal plate, and thereby maintains a constant contact pressure with the electrode. Some plate terminals are bent into a tubular shape with a substantially constant curvature, and others are polygonal shapes that are discontinuously bent at several places.

[0017]

The oxygen detecting element of the oxygen sensor of the present invention is provided with a plate-shaped terminal, and the plate-shaped terminal can be moved in the axial direction by locking the convex portion or the concave portion with the solid electrolyte. It is suppressed. Therefore, even if a tensile force acts on the lead wire, the plate-like terminal does not move and separate from the electrode.

Therefore, a stopper made of resin (reference numeral 973) for restraining the axial movement of the plate-like terminal becomes unnecessary, and the weakness of the stopper, which is a weak point, to thermal stress is eliminated. It A predetermined contact pressure is secured between the plate-shaped terminal and the electrode by the bending elastic force of the metal plate, and stable electrical continuity is secured.

As described above, according to the present invention, it is possible to provide an oxygen sensor which can stably secure electrical connection between a lead wire and an oxygen detection element without using a resin member which is weak against heat. You can

[0020]

EXAMPLE An oxygen sensor according to an example of the present invention will be described with reference to FIGS. In this example, as shown in FIG. 1, a cylindrical oxygen sensing element 20 with one end closed.
A housing 11 for accommodating the oxygen detection element 20 and mounted in the exhaust gas passage, a lead wire 121 for connecting the oxygen detection element 20 and the housing 11 in the housing 11, and for extracting an output drawn from an end portion 111 of the housing 11. And an exhaust gas oxygen sensor 10 for an internal combustion engine having 122.

The oxygen sensing element 20 is a cylindrical solid electrolyte 2
1 and an internal electrode 22 provided on the inner peripheral side of the solid electrolyte 21.
And an external electrode 23 provided on the outer peripheral side, and a pair of plate-shaped terminals 31 and 32 for sandwiching the internal electrode 22 and the external electrode 23 by the bending elastic force of the metal plate.

As shown in FIGS. 2 and 4, the plate-like terminals 31 and 32 are provided with recesses 33 for engaging with the solid electrolyte 21.
34 is provided. On the other hand, as shown in FIGS. 3 and 5, the solid electrolyte 21 is provided with a groove 24 that engages with the recesses 33 and 34 and suppresses the axial movement of the plate terminals 31 and 32. Further, the plate terminals 31 and 32 are connected to the lead wires 121 and 122 as shown in FIG.

Each of these will be described in detail below. The housing 11 containing the oxygen detection element 20 has a flange 131.
Body portion 13 having an exhaust cover 14 and an exhaust cover 14 constituting the tip side
And an atmosphere cover 15 constituting the base end side. The exhaust cover 14 has exhaust ports 141, 14 for taking in exhaust gas.
2 is drilled.

The atmosphere cover 15 is provided with an atmosphere intake (not shown) for introducing the atmosphere. The oxygen detection element 20 is sandwiched by the body 13 via the insulating member 16. On the other hand, from the base end of the housing 11,
The lead wires 121 and 122 are drawn out through the rubber bush 17.

On the other hand, on the base end side of the oxygen sensing element 20,
A first plate-shaped terminal 31 that sandwiches the internal electrode 22 and a second plate-shaped terminal 32 that sandwiches the external electrode 23 are provided. Between the first plate-shaped terminal 31 and the second plate-shaped terminal 32, As shown in FIGS. 3 and 5, the solid electrolyte 21 is provided with a groove 24 along the outer peripheral direction of the solid electrolyte 21.

The contact plate 311 of the first plate-shaped terminal 31
As shown in FIG. 2, a substantially triangular recess 33 is formed below. On the other hand, as shown in FIG. 4, a substantially triangular recess 34 is similarly formed at the connecting portion between the contact plate 321 and the terminal piece 322 of the second plate terminal 32.
4 is locked in the groove 24, as shown in FIG.

The recess is not limited to the triangular shape, but may have various shapes. For example, as shown in FIGS. 6 and 7, there is a circular recess 331, and as shown in FIGS. 8 to 10, there is a recess 332 that connects the contact plates 311 in a U-shape.

Further, as shown in FIGS. 11 and 12, a recess 333 in which a projecting piece is provided on the terminal piece 323 of the second plate-shaped terminal 32.
Alternatively, as shown in FIGS. 13 and 14, the contact plate 324 of the second plate-shaped terminal 32 has a recess 334 provided with a protrusion. Also,
The groove 24 may be provided in conformity with the recess, and does not necessarily have to be a groove that goes around the outer circumference of the solid electrolyte 21. Furthermore, in the present embodiment, a cylindrical oxygen sensing element with one end closed is adopted, but the shape of the oxygen sensing element is not limited to this, and may be, for example, a laminated oxygen sensing element having a rectangular cross section. .

As described above, since the oxygen sensor 10 of this embodiment is provided with the engaging pair consisting of the concave portion 33 and the groove 24, the axial movement of the plate-like terminals 31, 32 is restrained. Further, a predetermined contact pressure is secured between the plate-shaped terminals 31, 32 and the electrodes 22, 23 by the bending elastic force of the metal plate,
Stable electrical continuity is secured.

As described above, according to this example, the oxygen sensor capable of stably ensuring the electrical connection between the lead wires 121 and 122 and the oxygen detection element 20 without using a resin member which is weak against heat. 10 can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of an oxygen sensor according to an embodiment.

FIG. 2 is a development view of a first plate-shaped terminal of the oxygen sensor of the embodiment.

FIG. 3 is a partially enlarged cross-sectional view of an engaging portion of the first plate terminal of FIG.

FIG. 4 is a development view of a second plate-shaped terminal of the oxygen sensor of the embodiment.

5 is a partial enlarged cross-sectional view of an engaging portion of the second plate-shaped terminal of FIG.

FIG. 6 is a development view of another first plate-shaped terminal of the oxygen sensor of the embodiment.

FIG. 7 is a partially enlarged cross-sectional view of an engaging portion of the first plate terminal of FIG.

8 is a development view of another first plate-shaped terminal of the oxygen sensor of FIG.

9 is a partially enlarged cross-sectional view of an engaging portion of the first plate terminal of FIG.

10 is a perspective view of the first plate-shaped terminal of FIG.

FIG. 11 is a development view of another second plate-shaped terminal of the oxygen sensor of the example.

12 is a partial enlarged cross-sectional view of an engaging portion of the second plate-shaped terminal of FIG.

FIG. 13 is a development view of another second plate-shaped terminal of the oxygen sensor of the example.

14 is a partially enlarged cross-sectional view of an engaging portion of the second plate-shaped terminal of FIG.

FIG. 15 is a sectional view of a conventional oxygen sensor.

16 is an enlarged perspective view around the plate-shaped terminal of FIG.

17 is a development view of the plate-like terminal of FIG.

FIG. 18 is a perspective view of the plate-shaped terminal of FIG. 17 after bending.

[Explanation of symbols]

 10. ． ． Oxygen sensor, 121, 122. ． ． Lead wire, 20. ． ． Oxygen sensing element, 21. ． ． Solid electrolyte, 22. ． ． Internal electrodes, 23. ． ． External electrode, 24. ． ． Groove, 31, 32. ． ． Plate-like terminal, 33. ． ． Recess,

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryuji Fujiwara, 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Katsura Yamada, 1-1, Showa-cho, Kariya city, Aichi prefecture Incorporated (72) Inventor Masatoshi 1-1 1-1 Showa-cho, Kariya city, Aichi prefecture

Claims (1)

[Claims] 1. An oxygen sensing element that obtains an output corresponding to oxygen concentration, a housing that houses the oxygen sensing element and is mounted in an exhaust gas passage, and an end portion of the housing that is connected to the oxygen sensing element in the housing. An oxygen sensor having a lead wire for extracting output from the solid oxide, wherein the oxygen sensing element comprises a solid electrolyte, an inner electrode provided on the inner peripheral side of the solid electrolyte, and an outer electrode provided on the outer peripheral side. , A pair of plate-shaped terminals for sandwiching the internal electrode and the external electrode by bending elastic force of a metal plate, and the plate-shaped terminal has a concave portion or a convex portion for engaging with the solid electrolyte. On the other hand, the solid electrolyte is provided with a groove or a raised portion that engages with the concave portion or the convex portion and suppresses the axial movement of the plate-shaped terminal, and the plate-shaped terminal is That it is connected to the lead wire Characteristic oxygen sensor.