JP2002372513A - Seal structure in oxygen sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact seal structure in an oxygen sensor at a low cost by composing a seal member with permeability and sealability. SOLUTION: The seal member 30 disposed on a head part of the oxygen sensor and inserted in a seal holding part comprises a seal member body 31 and a permeable and sealable structure 32 fitted in a vent 311 of the seal member body 31. The permeable and sealable structure 32 has an outer cylinder 33 internally fitted to the vent 311, an inner cylinder 34 internally fitted to the outer cylinder 33, a water repellent filter 36 and an O-ring 37 which are disposed in a space part 35 between a tapered part 331 of the outer cylinder 33 and a narrow part 341 of the inner cylinder 34. Both ends of the outer cylinder 33 and the inner cylinder 34 are opened, and the water repellent filter 36 are disposed to cover one opening of the inner cylinder 34. The O-ring 37 is closely attached together with the water repellent filter 36 by inserting the inner cylinder 34 in the outer cylinder 33 to press and deform the O-ring 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having an internal combustion engine, and more particularly to a seal structure for an oxygen sensor for detecting the concentration of oxygen contained in exhaust gas generated from a vehicle.

[0002]

2. Description of the Related Art With the spread of vehicles, particularly automobiles, exhaust gas regulations for restricting exhaust gas emitted from automobiles have been strengthened. In recent years, in response to this regulation, an exhaust gas purification system using a combination of a three-way catalyst and electronically controlled fuel injection has been developed. In order to make effective use of the three-way catalyst, it is necessary to correct the air-fuel efficiency to the center of the window. For this reason, an oxygen sensor for detecting the oxygen concentration of the exhaust gas has been mounted on automobiles.

[0003] As a typical example of the conventional oxygen sensor, an oxygen detection element has platinum electrodes on both sides of a solid electrolyte mainly composed of zirconia ceramics as an oxygen ion conductor, and has an electrode on the outer periphery of the outer electrode. Many are provided with a protective ceramic coating layer.

[0004] That is, the oxygen sensor 50 is shown in FIGS.
As shown in the figure, the oxygen detecting element 52 is housed in a cylindrical housing 51 and a heater 53 is inserted into the hollow part of the oxygen detecting element 52. The heater 53 is disposed so as to heat the element sensing unit 52a to the operating temperature range.
a is covered by a cylindrical metal protective cover 54 formed at the lower part of the housing 51. In addition, the oxygen detecting element 5
2 is insulated and fixed to the housing 51, is configured to prevent leakage of exhaust gas to the atmosphere side electrode, and is equipped with a rubber bush 55 to prevent rainwater from entering the oxygen sensor. Enhances sealing performance and ensures ventilation. Lead wire 5 is attached to rubber bush 55
6, a terminal connected to the lead wire 56 is disposed in a ceramic separator 57 disposed below the rubber bush 55, and is connected to the heater 53.

[0005] In the oxygen sensor 50, it is important to consider waterproofness for preventing abrupt changes in oxygen concentration due to attachment of poisoning substances or water to the element sensing portion 52a or ventilation for air introduction. Have been.

For this reason, in the conventional oxygen sensor, at the sensor head, a porous Teflon (registered trademark) material is provided around the ceramic separator 57 in order to achieve both air permeability and waterproofness for air introduction. Water repellent filter 58
Is provided. Further, a protective cover for covering the porous water-repellent filter 58 is formed between the ceramic separator 57 and the porous water-repellent filter 58 so as to provide air permeability in the sensor (formed on the upper part of the housing 51). 5
9 are provided with gas introduction holes 59a and 59b communicating with each other from the side.

[0007]

However, in the conventional oxygen sensor 50, the porous water-repellent filter 58 and the rubber bush 55 are separately disposed in order to achieve air permeability and waterproofness. When assembling the sensor 1, manual work is increased, productivity is reduced, the number of parts is increased, cost is increased, and air permeability is improved by providing gas introduction holes 59 a and 59 b communicating from the protective cover 59. As a result, not only is the structure complicated, but also the waterproof cover lacks stability due to the increase in the number of sealing portions formed by caulking the protective cover 59.

The present invention has been made to solve the above-mentioned problems, and can be made compact so as to reduce the cost by improving the productivity of the assembling work, and to stabilize the waterproofness. An object is to provide a seal structure in an oxygen sensor.

[0009]

Means for Solving the Problems In order to solve the above problems, the seal structure of the oxygen sensor according to the present invention is configured as follows. That is, an oxygen detecting element is disposed in a cylindrical housing, a lead wire connected from the outside is wired to the oxygen detecting element, and ventilation means for protecting the air permeability of the oxygen detecting element and protecting the waterproofness are provided. A sealing member provided in a head of the oxygen sensor, wherein the sealing member is surrounded by the housing and includes a sealing member passing through the lead wire. The sealing member is provided with ventilation means, and the ventilation means is provided with a filter layer.

Preferably, the ventilation means is a double-opened pipe member insertable into a ventilation hole formed in the seal member, and a water-repellent filter layer is provided at one open port of the double-opened pipe member. It is sufficient if they are provided.

Further, if the two-opening pipe member has a double structure of an inner cylinder and an outer cylinder, and if a ring-shaped seal member is provided between the inner cylinder and the outer cylinder, Better.

Further, the inner cylinder may be arranged so as to be able to press the ring-shaped seal member by being pressed from one end side by a plug member fitted inside the outer cylinder and having both ends opened.

[0013]

According to the sealing structure of the oxygen sensor of the present invention, the sealing member for protecting the oxygen detecting element is provided with the ventilation means for disposing the filter layer as described above. Protected by layers, the introduction of air can be performed by ventilation means, and by inserting a sealing member into the head of the oxygen sensor, to ensure sealing and ventilation against ingress of rainwater, muddy water, oil, etc. Can be. Therefore, since the seal structure of the oxygen sensor of the present invention is provided with the ventilation means and the filter means in the seal member, the assembly of the seal member itself and the assembly of the seal member to the oxygen sensor can be performed by an automatic machine. As a result, the productivity can be improved, and the configuration can be made extremely compact, and the cost can be reduced.

Further, the ventilation means is a double-opened pipe member insertable into a ventilation hole formed in the seal member, and a water-repellent filter layer is disposed at one open port of the double-opened pipe member. Therefore, the air permeability can be secured by the pipe member with one seal member, and the waterproof property can be protected by the water-repellent filter.
Therefore, a compactly configured oxygen sensor can be provided.

The double-opened pipe member has a double structure of an inner cylinder and an outer cylinder, and a ring-shaped sealing member is provided between the inner cylinder and the outer cylinder. Therefore, by arranging a ring-shaped seal member, for example, an O-ring, the waterproofness can be further improved.

Further, if the inner cylinder is arranged so as to be pressed from one end side by a plug member internally fitted in the outer cylinder, the inner cylinder pressed by the plug member is connected to the ring-shaped sealing member. By pressing, the ring-shaped seal member is deformed, and can be closely attached to the outer cylinder and the inner cylinder,
Furthermore, waterproofness can be improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The seal structure of the oxygen sensor of the present invention is mainly indicated by a seal member formed of a rubber material disposed on the head of the oxygen sensor. As shown in FIGS. 1 and 2, the oxygen sensor 1 has a heating element (heater) 2 supported by a heating element gripping section 3 and provided with a heating section 201 at a distal end.
Is suspended in the axial direction, and the oxygen detecting element 4
And the oxygen detecting element 4 is housed in a cylindrical housing 10. A ceramic separator 5 is disposed above the oxygen detection element 4 and holds lead wires 6 connected to the oxygen detection element 4 and the heating element gripping portion 3, respectively.

The housing 10 has a protector 11 formed at its lower end with a closed end to protect the heat generating portion 201, a mounting bracket 12 disposed above the protector 11, and an upper part of the mounting bracket 12. Main cylinder part 13 arranged in
And a seal holding portion 14 which is disposed so as to surround the upper outer periphery of the main cylindrical portion 13 and extends upward, and is formed with an open upper end portion. At the upper end of the housing 10,
A plurality of (four in the embodiment) seal members 20 are arranged so as to be in close contact with the inner peripheral surface of the seal holding portion 14.
Lead wire 6 is inserted.

The oxygen detecting element 4 has platinum electrodes on both sides of a cup-shaped solid electrolyte mainly composed of zirconia (ZrO ₂ ) ceramic as an oxygen ion conductor, and a ceramic for protecting the electrodes on the outer periphery of the outer electrode. It is provided with a coating layer.

As shown in FIG. 2, the seal member 20 is formed of a rubber material to be elastic and substantially columnar, and has a ventilation hole 211 formed along the axis. And a ventilation / seal structure portion 22 inserted into the ventilation hole 211. The seal member main body 21 has a plurality of insertion holes 212 (four in the embodiment) for inserting the lead wire 6 around the ventilation hole 211.

The ventilation / seal structure 22 is provided for the oxygen sensor 1.
It is provided for the purpose of having a gas permeability between the inside and the outside and preventing the intrusion of fluid from the outside, and is provided for the purpose of the first embodiment as shown in FIG. Thus, the pipe member 23 is made of a metal material having both ends opened, and the water-repellent filter 24 fitted tightly between the outer peripheral surface of the pipe member 23 and the air hole 211, and has an elliptical or true shape. With the circular water-repellent filter 24 applied to one end of the pipe member 23, the sealing member body 21
Of the ventilation hole 211 from one end side.

The pipe member 23 has a flange 231 at one end.
Is formed as a fitting stopper when the water repellent filter 24 is pushed into the vent hole 211. The water repellent filter 24 is made of a cured elastic copolymer of a perfluoroolefin and at least one other perfluoro comonomer, and is a material formed so as to prevent water from passing through air. The water repellent filter 24 may be attached to the opening at one end of the pipe member 23 by welding.

Since the water-repellent filter 24 is provided on the entire peripheral surface of the ventilation / seal structure portion 22 except for one opening of the pipe member 23, the ventilation / seal structure portion 22 ensures the air permeability and the waterproofness. Can be improved.

The above-mentioned seal member 20 is assembled by inserting a water-repellent filter 24 and a pipe member 23 into a seal member body 21 by an automatic machine to form a ventilation / seal structure 22. Then, after the lead wire 6 is inserted through the seal member 20 having the ventilation / seal structure 22, the heating element 2 and the oxygen detection element 4 are automatically or manually operated.
The oxygen sensor 1 is configured by being mounted on the head of the oxygen sensor 1 in which is incorporated.

Therefore, in the seal structure of the oxygen sensor of the present invention in the embodiment, the pipe member 23 having both openings is incorporated in the seal member 20 for protecting the oxygen detection element 4 as described above. Since the water-repellent filter 24 that does not allow water to pass through the air is attached to one of the openings, the waterproof is protected by the water-repellent filter layer 24 of the seal member 20, and the air is removed from the pipe member 23 by the water-repellent filter 24. The oxygen gas passes through the inside of the oxygen sensor 1. Therefore, by attaching one seal member 20 to the head of the oxygen sensor 1, it is possible to secure air permeability and waterproof property against rainwater intrusion from the outside, and to reduce the cost with an extremely compact configuration. Becomes possible. In addition, the assembly of the seal member itself and the assembly of the seal member to the oxygen sensor can be performed by an automatic machine, so that productivity can be improved.

Next, the pipe member 23 and the water repellent filter 2
As for the ventilation / seal structure portion 22 configured to include the above, various forms other than the above forms can be shown.

For example, in the ventilation / seal structure portion 22A of the form shown in FIG. 4, the pipe member 23A has a curved portion 232 projecting outward at several places in the longitudinal direction.
Therefore, even in the water repellent filter 24A, the pipe member 2
By forming a curved surface 212 along the curved portion 232 of the pipe member 23A in the vent hole 211 of the seal member main body 21A, the ventilation / seal structure 22A is formed in a curved shape along the curved portion 232 of the 3A. Member body 21A
Is configured to be able to prevent disconnection.

Further, another form of the ventilation / seal structure 2
5B, as shown in FIG. 5, an outer cylinder 25 made of a metal material, which is disposed on the outer peripheral surface of the water repellent filter 24B, is fitted inside the inner peripheral surface of the vent hole 211, and has both ends opened. Good. The ventilation / seal structure portion 22B of this embodiment forms a double cylinder, and the water-repellent filter 24B is used as the pipe member 2 of the inner cylinder.
3B and the outer cylinder 25 to support the water repellent filter 24B and protect the water repellent filter 2B.
By pressing the 4B, the sealing property can be improved.

As shown in FIG. 6, the use area of the water-repellent filter 24C is reduced to close one opening of the pipe member 23C and a part of the side of the pipe member 23C is made of a metal material. Cover with tube 26 (see FIG. 6a) or
Alternatively, it is covered with an outer cylinder 27 made of a resin material (see FIG. 6B), or
Alternatively, as shown in FIG. 7, one end of the pipe member 23C is interposed so as to lock the inner locking portion 191 of the ring-shaped sealing member 19, and the water-repellent filter 24 is provided on the outer peripheral surface thereof.
C may be attached and inserted into the vent hole 211 of the seal member 21C. In this case, the expensive water-repellent filter 24C can be saved.

Further, it is also possible to cover only one opening of the pipe member 23 with the water repellent filter 24 and to support the water repellent filter 24 from one side of the seal member main body 21.
For example, the ventilation / seal structure portion 22D shown in FIG. 8 is configured such that a small width ring groove 213 is formed at one end of a seal member main body 21D around a pipe member 23D fitted in the ventilation hole 211. 24D is mounted so as to be pushed into the ring groove 213 by a cylindrical ring pipe 28 formed of a metal material.

Further, in the ventilation / seal structure 22E shown in FIGS. 9 to 10, a water-repellent filter 24E is arranged on one side of the ventilation hole 211 of the sealing member main body 21E.
Closing part 1 formed by closing one end of seal holding part 14
41, the water-repellent filter 24E
To one end of the seal member body 21E. At this time, a ventilation opening 143 is formed in the closing part 141 of the seal holding part 14 at a position facing the ventilation hole 211 of the sealing member main body 21E.

Further, the ventilation / seal structure portion 22F of the form shown in FIG. 11 has a pipe member 23F having a large head portion 232 and a small body portion 233 having a smaller diameter than the head portion. 211. The large-diameter head 232 has a groove 234 formed on the entire inner peripheral surface thereof, and the water-repellent filter 24F is gripped and mounted in the groove 234.

Next, a second embodiment in which an inner cylinder and an outer cylinder are provided, and a ring-shaped seal member is arranged between the inner cylinder and the outer cylinder will be described. In this embodiment, by disposing a ring-shaped seal member, the water-repellent filter is assembled without being damaged, and the waterproof property is improved.

The seal member 30 shown in FIG. 12 is disposed so as to be in close contact with the head of the seal holding portion 14, is formed of a rubber material in an elastic shape and is formed in a substantially columnar shape, and is formed along the axis. Seal member main body 3 in which ventilation hole 311 is formed
1 and the ventilation / seal structure 32 inserted into the ventilation hole 311
And is configured. A plurality of (four in the embodiment) lead wires 6 are closely inserted through the seal member 30 around the ventilation hole 311.

As shown in FIG. 13, the ventilation / seal structure portion 32 is formed in a pipe shape and has an outer cylinder 33 made of a metal material fitted inside the ventilation hole 311, and a pipe shape fitted inside the outer cylinder 33. And the inner cylinder 34 made of a metal material is formed as a double cylinder. One end of the outer cylinder 33 is formed with a narrowed portion 331 so as to narrow toward the tip, and the other end is formed with a flange 332 that can abut on the other end surface of the seal member main body 31. On one end side, a throttle portion 331 of the outer cylinder 33 is provided.
A curved narrow portion 341 is formed so as to have a space portion 35 between itself and the inner side surface. A water-repellent filter 36 is disposed in a space 35 between the narrowed portion 331 of the outer cylinder 33 and the narrowed portion 341 of the inner cylinder 34 so as to house the peripheral portion thereof, and the narrowed portion 341 of the inner cylinder 34 and the water-repellent filter are arranged. An O-ring 37 as a ring-shaped sealing member is disposed between the O-ring 37 and the O-ring 36.

The ventilation / seal structure 32 of this embodiment is formed by bringing a water-repellent filter 36 disposed between an upper portion of the outer tube 33 and an upper portion of the inner tube 34 into close contact with a compressed O-ring 37. Further, the waterproofness is improved.

The above-mentioned sealing member 30 is assembled with the ventilation / seal structure 32 first. That is, the O-ring 37 is fitted along the outer peripheral surface of the narrow portion 341 of the inner cylinder 34, and the inner cylinder 34 is attached to the outer cylinder 33 by an automatic machine in a state where the water-repellent filter 36 is arranged so as to cover the O-ring 37. To fit inside. Then, the water-repellent filter 36 is connected to the throttle 3 of the outer cylinder 33.
When the O-ring 37 reaches a position where it comes into contact with the inner peripheral surface of the outer cylinder 33, the O-ring 37 is compressed by the further insertion of the inner cylinder 34, and the outer cylinder 33 is compressed.
The space 35 to be formed between the narrowed portion 331 of the inner cylinder 34 and the narrow portion 341 of the inner cylinder 34 is filled, and the O-ring 37 is It is in close contact with the inner cylinder 34. Thus, the ventilation / seal structure 32 is assembled, and the ventilation / seal structure 32 is inserted into the seal member main body 31 by an automatic machine, whereby the seal member 30 is formed. After the lead wire 6 is inserted through the sealing member 30 having the ventilation / seal structure 32, the head of the oxygen sensor 1 in which the heating element 2 and the oxygen detecting element 4 are incorporated by an automatic machine or manually. The oxygen sensor 1 is configured by being attached to the unit.

As described above, the ventilation / seal structure 32
Has a double structure of an inner cylinder 34 and an outer cylinder 33, and by disposing an O-ring 37 between the inner cylinder 34 and the outer cylinder 33, the water-repellent filter 36 is attached to the inner cylinder 34 and the outer cylinder 33. 33
If the water repellent filter 36 is tightly held without damaging the water repellent filter 36, the waterproof property can be further improved by the close contact of the O-ring 37. In addition, the outer cylinder can be ventilated into the oxygen sensor 1 by the inner cylinder 34, the outer cylinder 33, and the water-repellent filter 36, both ends of which are open, and the inexpensive oxygen sensor 1 can be provided with a compact configuration. it can.

As shown in FIG. 14, another form of the ventilation / seal structure portion 32A is a seal member main body portion 31A.
A into the outer cylinder 33A fitted in the ventilation hole 311 of the inner cylinder 34.
A and a plug 38 that presses the inner cylinder 34A from below are arranged. The inner cylinder 34A has openings at both ends and is formed to be approximately half the length of the outer cylinder 33A, and has a tapered portion 342 at the tip end. The plug 38 has an opening at both ends and has a pressing surface 381 for pressing the lower end surface of the inner cylinder 34A, and is formed in a stepped cylindrical shape, and the tip end is fitted inside the inner peripheral surface of the tapered portion 342 of the inner cylinder 34A. It is formed as follows. Tapered portion 342 of inner cylinder 34A and outer cylinder 3
A space 35A is formed between the narrowed portion 331A formed so as to be narrow at the tip of the inner tube 3A, and a water-repellent filter 36A is disposed in the space 35A so as to house the peripheral portion thereof. 342 and water repellent filter 36A
A tapered flat packing or a rubber bush 37A as a ring-shaped seal member is disposed between them. When the tapered flat packing 37A is pressed by the plug 38 via the inner cylinder 34A, the water-repellent filter 36A is pressed against the narrowed portion 331A of the outer cylinder 33A to improve the sealing performance of the tapered flat packing 37A. it can. In the case of this embodiment, the plug 38 has a tapered pressing portion so that the tapered flat packing 37A can be sandwiched between the plug 38 and the water-repellent filter 36A, and is formed of a ring-shaped metal material. Or a ring-shaped member made of a rubber material having a tapered surface at the tip.

It should be noted that the seal member 20 shown as described above is used.
(Or 30) is arranged above the oxygen sensor 1 so as to be in close contact with the housing.
However, the present invention is not limited to the above, and can be used for other known oxygen sensors.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an oxygen sensor according to one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part in FIG.

FIG. 3 is an enlarged sectional view of a main part showing a seal structure of a first embodiment in FIG. 1;

FIG. 4 is a sectional view showing another embodiment of the seal structure in FIG. 3;

FIG. 5 is a cross-sectional view showing a seal structure of still another embodiment.

FIG. 6 is a cross-sectional view showing a seal structure of still another embodiment.

FIG. 7 is a cross-sectional view showing a seal structure of still another embodiment.

FIG. 8 is a cross-sectional view showing still another form of the seal structure.

FIG. 9 is a plan view showing still another form of the seal structure.

FIG. 10 is a cross-sectional view showing a seal structure of still another embodiment.

FIG. 11 is a cross-sectional view showing still another form of the seal structure.

FIG. 12 is an enlarged sectional view showing a seal structure of an oxygen sensor according to a second embodiment of the present invention.

FIG. 13 is a sectional view showing the seal structure in FIG.

14 is a cross-sectional view showing another embodiment of the seal structure in FIG.

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

16 is an enlarged sectional view of a main part in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Oxygen sensor 2 ... Heating element 4 ... Oxygen sensor element 6 ... Lead wire 10 ... Housing 14 ... Seal holding part 20, 30 ... Seal member 21, 31 ... Seal member main body 211, 311 ... Vent hole 22, 32 ... Ventilation Seal structure 23 ... Pipe member 24, 36 ... Water-repellent filter 33 ... Outer tube 34 ... Inner tube 37 ... O-ring (ring-shaped seal member) 37A ... Tapered flat packing 38 ... Plug (plug member)

Claims (4)

[Claims] An oxygen detecting element is provided in a cylindrical housing, a lead wire connected from the outside is wired to the oxygen detecting element, and a ventilation means for protecting the air permeability of the oxygen detecting element and a waterproof. A seal structure in an oxygen sensor provided with sealing means for protecting the property, wherein the sealing means is provided at the head of the oxygen sensor,
A seal structure in an oxygen sensor, comprising a seal member surrounded by the housing and through which the lead wire is inserted, wherein the seal member is provided with a ventilation unit, and the ventilation unit is provided with a filter layer. . 2. The double-opening pipe member, wherein the ventilation means can be inserted into a ventilation hole formed in the seal member,
The seal structure according to claim 1, wherein a water-repellent filter layer is provided at one open port of the two-way pipe member. 3. The double-opened pipe member has a double structure of an inner cylinder and an outer cylinder, and between the inner cylinder and the outer cylinder,
3. The seal structure for an oxygen sensor according to claim 2, wherein a ring-shaped seal member is provided. 4. The inner cylinder is arranged so as to be pressed from one end side by a plug member which is internally fitted into the outer cylinder and has both ends opened, so as to be able to press the ring-shaped seal member. The seal structure in the oxygen sensor according to claim 3.