JPH079078Y2 - Oxygen sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an oxygen sensor arranged in an exhaust pipe of an internal combustion engine.

[Prior Art] Conventionally, in a structure in which a coated lead wire is taken out watertight from a cylindrical portion protruding from a mounting bracket of a device or the like, in order to improve durability when a tensile force is applied to the coated lead wire. As shown in FIG. 4, a covering lead wire mounting structure is employed.

In this structure, the oxygen sensor C screwed to the exhaust pipe M is connected in a structure in which the covered lead wire 102 is taken out in a watertight manner from the take-out tube protruding from the fitting of the oxygen sensor body K which is an electric device. The metal fitting 101 is used. One end of the connection fitting 101 serves as the grip portion 44, and the coated lead wire 1
It is fitted on the end 105 of 02.

The take-out tube 15 has a connecting tube 8 for reinforcing the covered lead wire 102.
Is externally fitted, the tip thereof is narrowed to a small diameter, and the grommet 107 is fitted therein.

The grommet 107 is locked to the locking portion 8K at the narrowed tip of the connecting tube 8 and the covered lead wire 10 near the gripping portion 44.
The wrapping 2 and the connecting tube 8 have the crimped portion 8A and the take-out tube 1
Sticked to 5.

[Problems to be solved by the invention] However, in the conventional configuration, when a strong pulling force is applied to the coated lead wire 102, the grommet 107 is an elastic body (adopted for elastically mounting the connection fitting 101 to prevent vibration). Therefore, most of the pulling force is applied to the connection metal fitting 101, connection failure between the connection terminal 104 and the coated lead wire 102 or damage to electric equipment occurs, or metal fatigue progresses due to vibration from the internal combustion engine to connect. There was a drawback that the metal fittings were damaged.

An object of the present invention is to provide an oxygen sensor having a strength capable of preventing metal fatigue of a connecting fitting due to vibration and capable of withstanding a sufficient tensile force even when an extremely strong tensile force is applied to a coated lead wire. It is in.

[Means for Solving the Problems] To achieve the above object, the present invention employs the following configurations.

(1) A heat-resistant metal fitting provided in an exhaust pipe of an internal combustion engine, and an oxygen sensor element held in the fitting.
A plurality of ejecting cylinders protruding from the rear end of the mounting bracket, a connecting cylinder externally fitted to the rear part of the ejecting cylinder, a tip end electrically connected to the oxygen sensor element, and a rear end gripping portion. Of the connecting cylinder, which is fitted in the connecting cylinder, is made of an elastic material, has an through hole group through which the connecting metal is inserted, and has a plurality of through holes. A grommet fitted to the end, fitted between the insulating separator and the grommet, an electrically insulating rigid plate having a plurality of lead wire insertion holes, a through hole of the grommet and the lead wire insertion hole. As described above, the rear end grip portion of the connection fitting includes a plurality of coated lead wires for holding a core wire, and the connection fitting is elastically retained in the through hole of the insulation separator by the insulation separator. At the same time, the rear end gripping part is attached to the rigid plate. It is locked Rigakari.

(2) With the configuration of (1) above, the rigid plate has a hardness of 15
Hv or more and thickness 1 mm or more.

[Operation and Effect of Invention] (Claim 1) The tensile force applied to the coated lead wire is transmitted to the connection fitting by the rear end gripping portion gripping the core wire. However, since the rear end grip portion is locked to the rigid plate which is a rigid body, most of the pulling force is transmitted to the connecting cylinder via the rigid plate and is only slightly transmitted to the oxygen sensor element. Problems such as breakage of the oxygen sensor element, disconnection of the connection fitting and the oxygen sensor element, and pulling out of the coated lead wire can be prevented.

Since the connecting fitting is elastically held in the through hole of the insulating separator by the insulating separator, metal fatigue of the connecting fitting due to vibration can be prevented.

(Claim 2) If the hardness is 15 Hv or more and the thickness is 1 mm or more, the rigid plate does not deform even if the maximum tensile force load (about 40 kgf) that can occur during use is applied to the coated lead wire, Rearward displacement can be prevented.

[Embodiment] Next, the present invention will be explained based on an embodiment shown in FIGS.

The oxygen sensor A includes a sensor body 100, a heater 300 installed therein, a coated lead wire 500 for taking out the output of the sensor body 100 and the heater 300 and supplying power, and a watertight coated lead from the sensor body 100. It is composed of a lead wire connecting portion 700 for taking out the wires 51, 52 and 53.

The sensor body 100 includes a housing 1 made of heat-resistant metal and an oxygen sensor element 2 held in the housing 1.

The housing 1 has a cylindrical mounting member 10 having mounting screws 11 and hexagonal portions 12 formed on the outer periphery, and a cylindrical shape with a closed front end and an open rear end. And a cylindrical protective crown 14 provided with a large number of ventilation holes 13 for allowing exhaust air to flow in and out on the cylindrical surface, and coaxially caulked and fixed to the rear end of the mounting bracket 10 to protect device terminals and cover lead wires 51. , 52,
A take-out tube protruding from the mounting bracket 10 of the device of the present invention, which also serves as a connection for 53, and takes out the coated lead wires 51, 52, 53
It consists of fifteen.

The oxygen sensor element 2 is made of an oxygen ion conductive solid electrolyte ceramic, and is formed by coating a porous electrode on the inner and outer surfaces of a cylinder whose tip 21 is closed. The oxygen sensor element 2 is mounted on the housing 1 via a talc 23 for sealing and a heat-resistant metal tube 25.
It is fixed inside.

The heater 300 is formed by embedding a heating wire in a rod-shaped ceramic body and is fitted in the oxygen sensor element 2. Terminals of the heating wire are exposed at the rear end of the heater 300, and the exposed surfaces serving as the connection terminals are brazed with the tip end portions 31A and 32A of the strip-shaped connection fittings 31 and 23. .
Further, the open end 22 of the oxygen sensor element 2 has a cylindrical portion 41 which is inscribed and connected to the porous electrode layer on the inner surface, and front and rear thereof have external fitting portions 42 and 43 for holding the outer periphery of the heater 300. The connection fitting 4 having the above is fitted and connected to the end portion 53T of the coated lead wire 53.

The coated lead wire 500 is formed by bundling coated lead wires 51, 52 for energizing the heater 300 and a coated lead wire 53 for extracting the output of the sensor element connected to the connection fitting 4, and wrapping this with a mesh 55. Has been done.

In the lead wire connection portion 700, the rear ends of the connection fittings 31, 32 and the connection fitting 4 are electrically connected to the end portions 51T, 52T, 53T of the core wires of the coated lead wires 51, 52, 53, respectively. And the cylindrical surface-shaped gripping portions 31B, 32B and 44 provided at the rear ends of the respective grips.
Grips the coating of each coated lead wire 51, 52, 53 and is connected to each coated lead wire 51, 52, 53.

As shown in FIGS. 2 and 3, the portions of the connection fittings 31, 32 and the connection fitting 4 protruding from the take-out tube 15 are made of silicon rubber and have three axial through holes 61, 62, 63. It is inserted into each through hole of the columnar insulating separator 6 arranged in parallel. Further, the lead wires in the vicinity of the connection fittings 31, 32 and the connection fitting 4 are covered with through-holes 7 that are closely fitted to these coatings.
A silicon rubber grommet 7 in which 1, 72, 73 are arranged side by side is attached.

Further, between the tip of the insulating separator 6 and the rear end of the take-out tube 15,
A ring-shaped glass fiber-containing PTFE spacer 56 is inserted, and a separator 57 having a Y-shaped cross section is fitted inside the spacer 56.

The connecting cylinder 8 includes the take-out cylinder 15, the spacer 56, and the insulating separator 6.
And a tube for externally fitting the grommet 7 and for fixing the coated lead wire 500 to the housing 1 of the electric device. The connecting cylinder 8 is composed of a portion 81 fitted on the take-out cylinder 15 and the grommet 7.
The outer end of the grommet 7 is fastened to the outer end of the grommet 7 by caulking, and the rear end portion 83 is formed to have a slightly smaller diameter.

An electrically insulating rigid plate 9 is fitted between the insulating separator 6 and the grommet 7 in the connecting cylinder 8 orthogonally to the axis. This rigid plate 9 has a hardness of 15 Hv (Vickers hardness).
It is made of PEEK (polyether ether ketone), has an outer diameter similar to the inner diameter of the connecting cylinder 8, and has a disk shape with a thickness of about 1 mm. Inside the rigid plate 9, the outer diameters of the coatings of the coated lead wires 51, 52, 53 are substantially equal to each other, and the covered and gripped connection fittings 31, 32 and 32 of the coated lead wires 51, 52, 53 and Lead wire insertion holes 91, 92, 93 smaller than the outer diameters of the rear end grip portions 31B, 31B and 44 of the connection fitting 4 are formed.

The rigid plate 9 may be made of a material other than synthetic resin, but needs to be electrically insulating and preferably has a hardness of 15 Hv or higher. This is because the maximum tensile force applied to the lead wire is about 40 kgf, and a material with a thickness of 1 mm or more and a hardness of 15 Hv or more does not show deformation under such a tensile load.

Further, it is desirable that the outer dimension of the rigid plate 9 is larger than the inner diameter of the rear end portion 83 of the connecting tube 8.

In this configuration, when the oxygen sensor A is attached to the exhaust pipe of the internal combustion engine and a tensile force is applied to the coated lead wire 500,
Most of the pulling force is transmitted from the coated lead wires 51, 52, 53 to the connecting fittings 31, 32, 4, but the gripping portions 31B, 32B, 44 are restrained by the rigid plate 9, so most of the pulling force. Is transmitted to the connecting tube 8 via the rigid plate 9. Therefore, the connection fittings 31, 32
Also, the tensile force applied to the sensor main body 100 and the heater 300 via the connection fitting 4 becomes small, and the occurrence of connection failure and the damage of the oxygen sensor element 2 are prevented. Further, since the connecting tube 8 is a rigid body and has sufficient strength, it has durability against a considerable tensile force, and the coated lead wires 51, 52, 53 are difficult to pull out.

The rigid plate 9 is made of PEEK with a thickness of 1 mm and a hardness of 18 Hv.
The holes 91, 92, 93 of the rigid plate 9 have a diameter of 2 mm, and the rear end grip portion
The outer diameter of 31B, 32B, 44 is 2.5 mm, various coated lead wires 51, 52,
The outer diameter of the coating of 53 is 1.9 mm, the sensor main body 100 is screwed on, the coated lead wire 500 is pulled, and the strength is examined by a destructive test. When the rigid plate 9 is inserted, the average is 40 kgf, and when there is no insertion, The average was 25 kgf.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an oxygen sensor according to an embodiment of the present invention, FIGS. 2 and 3 are exploded views of relevant parts, and FIG. 4 is a cross-sectional view of a conventional oxygen sensor. In the figure, A ... Oxygen sensor, 2 ... Oxygen sensor element, 41 ... Cylindrical part (tip part), 4, 31, 32 ... Connection fitting, 6 ... Insulation separator, 7 ... Grommet, 8 ... Connection tube, 9 ... Rigidity Plate, 10 ... Mounting bracket, 15 ... Extraction cylinder, 31A, 32A ... Tip, 51, 52, 53 ...
Coated lead wire, 51T, 52T, 53T ... End part (rear end carrying part), 6
1, 62, 63, 71, 72, 73 ... Through hole, 91, 92, 93 ... Lead wire insertion hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Sato 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Nihon Special Ceramics Co., Ltd. (56) References Application No. 59-24789 -137366), a microfilm (JP, U) of the contents and drawings attached to the application.

Claims (2)

[Scope of utility model registration request] 1. A mounting bracket made of a heat-resistant metal, which is disposed in an exhaust pipe of an internal combustion engine, an oxygen sensor element held in the mounting bracket, and an extraction cylinder projecting from a rear end of the mounting bracket. A connecting cylinder that is externally fitted to the rear of the take-out cylinder; a plurality of connecting fittings having a tip end portion electrically connected to the oxygen sensor element and a rear end gripping portion; An insulating separator having a through hole group that is formed of a material and through which the connecting fitting is inserted; a grommet that has a plurality of through holes and is fitted to the rear end of the connecting cylinder; the insulating separator and the It is fitted between the grommet,
An electrically insulating rigid plate having a plurality of lead wire insertion holes, and a plurality of core wires which are passed through the through holes of the grommet and the lead wire insertion holes and are held by the rear end holding portion of the connection fitting. An oxygen sensor, comprising: a coated lead wire, wherein the connecting fitting is elastically held in the through hole of the insulating separator by the insulating separator, and the rear end grip portion is locked by the rigid plate. 2. The oxygen sensor according to claim 1, wherein the rigid plate has a hardness of 15 Hv or more and a thickness of 1 mm or more.