JPH0752615Y2 - Device for mounting oxygen sensor for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a mounting device for mounting an oxygen sensor for an internal combustion engine used for detecting the oxygen concentration in exhaust gas to an exhaust pipe.

<Prior Art> Conventional oxygen sensors for internal combustion engines include, for example, those shown in FIGS. 5 and 6 (see Japanese Patent Laid-Open No. 63-262559).

That is, for example, on an insulating substrate 5A made of alumina or the like, a sheet 5B made of, for example, a solid electrolyte for forming an air introduction hole 5F with one end closed in a substantially U-shaped plane, and a platinum inner side that also has a function as a catalyst A sensor element portion 5 constituted by sequentially laminating an oxygen ion conductive zirconia plate 5E provided with an electrode 5C and an outer electrode 5D is provided with a washer 6 and a talc from a middle portion to a base end portion of the sensor element portion 5. Layer 7 and glass layer 8
It is held in the holder 9 via. At the tip of the holder 9,
A protector 10 for protecting the sensor element portion 5 is attached, and the protector 10 has a slit 10 for introducing exhaust gas.
a is formed. 11 and 12 are an inner cap and an outer cap, respectively.

The oxygen sensor 13 having such a structure is provided with an exhaust pipe 14 through an exhaust nut 14 screwed to a holder 9 as shown in FIG.
15 It is attached to the wall with the tip facing the exhaust pipe.

As a result, the inside of the exhaust pipe 15 flows in the direction of the arrow in FIG. 7 depending on the difference in concentration between the oxygen concentration in the exhaust passing through the protector 10 and the oxygen concentration in the atmosphere introduced into the atmosphere introduction hole 5F. The oxygen concentration in the exhaust gas is detected based on the super power generated between the electrode 5C and the outer electrode 5D, and the air-fuel ratio of the air-fuel mixture drawn into the engine is detected and used for air-fuel ratio feedback control. In order to improve the operating characteristics and responsiveness of the oxygen sensor when the exhaust temperature is low, although not shown between the insulating substrate 5A and the sheet 5B, a heating heater sandwiched between the insulating sheets is provided to provide the sensor element section. 5 can be heated and activated.

<Problems to be Solved by the Invention> However, since the tip of the oxygen sensor 13 is generally attached at right angles to the exhaust flow in the exhaust pipe, in the case of such a plate-shaped sensor element, the electrode portion is Since it is on one side, it has directivity, and since the slit 10a of the protector 10 is provided substantially parallel to the sensor element portion 5, as shown in FIG. 8, the exhaust flow (arrows A, B, C The direction in which the exhaust gas hits the electrode surface of the sensor element portion 5 differs depending on the orientation of the electrode portion of the sensor element portion 5 with respect to the (direction). Therefore, there is a problem in that the exhaust amount of the exhaust component, for example, the nitrogen oxide NO _x , when the air-fuel ratio feedback control is performed, varies as shown in FIG. 9.

The present invention has been made in view of the above circumstances, and the exhaust gas impinges from the tip end side of the plate-shaped sensor element portion rather than the side surface thereof, so that the oxygen sensor exhibits a certain performance regardless of the mounting direction. The purpose is to be able to.

<Means for Solving the Problems> Therefore, in the present invention, in a mounting device for mounting an oxygen sensor for an internal combustion engine, which detects an oxygen concentration in exhaust gas by a plate-shaped sensor element portion facing the exhaust gas, to an exhaust pipe. An exhaust nut for fixing an oxygen sensor to the exhaust pipe wall surface, and an exhaust introduction pipe fixed to the exhaust pipe inner end surface of the exhaust nut so as to cover the sensor element portion periphery, and the exhaust introduction pipe, An exhaust gas introduction portion having an entire opening facing the exhaust gas flow is provided on the tip end side, and an exhaust gas discharge portion having a plurality of small holes along the circumferential direction is provided on the peripheral wall near the base end side.

Further, the mounting device of the oxygen sensor for an internal combustion engine, an exhaust nut for fixing the oxygen sensor to the exhaust pipe wall surface, and an exhaust introduction pipe fixed to the exhaust pipe inner end surface of the exhaust nut so as to cover the sensor element portion periphery. The exhaust gas introducing pipe has a straight cylindrical shape along the sensor element portion, and an exhaust gas introducing portion is provided with a plurality of slits radially provided with an opening projecting outward from the distal end surface thereof. The exhaust gas discharge portion is provided with a plurality of small holes along the circumferential direction on the peripheral wall near the base end side fixed to the exhaust nut.

<Operation> According to the oxygen sensor mounting device configured as described above,
Exhaust gas flows in from the front end portion of the exhaust introduction pipe, flows around the sensor element portion from the front end side toward the proximal end side, and is exhausted from the proximal end side exhaust discharge portion of the exhaust gas introduction pipe. As a result, the way in which the exhaust gas strikes does not differ depending on the orientation of the electrode surface of the sensor element portion.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings. still,
The same elements as those of the related art will be designated by the same reference numerals and description thereof will be omitted.

Referring to FIG. 1 showing a first embodiment of the present invention, the mounting device of the present embodiment is such that the oxygen sensor 13 is fixed to the wall surface of the exhaust pipe 15, and the oxygen sensor is attached to the exhaust pipe inner end surface.
An exhaust gas introducing pipe 21 is fixedly attached so as to cover around the protector 10 of 13. The exhaust introduction pipe 21 is bent into a substantially L shape, and a front end opening 22 at the entire front end thereof is provided so as to face the exhaust flow (indicated by an arrow in the figure) and serves as an exhaust introduction portion. ing. Further, a plurality of exhaust gas discharge holes 23 are provided as exhaust gas discharge portions along the circumferential direction on the peripheral wall near the base end side of the exhaust gas introduction pipe 21 fixed to the exhaust nut 14.

According to this structure, the exhaust gas flowing in the direction of the arrow in the drawing flows in from the front end opening portion 22 of the exhaust gas introduction pipe 21. The inflowing exhaust gas flows from the front end side to the base end side of the protector 10 along the exhaust gas introducing pipe 21 as indicated by an arrow in the figure, and is exhausted from the exhaust gas exhaust hole 23. Then, while flowing from the tip end side to the base end side of the protector 10, the protector 10 flows inward from around the protector 10 and hits the sensor element portion 5.

Therefore, regardless of the orientation of the electrode surface of the sensor element portion 5, the exhaust gas strikes the electrode portion substantially uniformly and the directivity of the electrode portion disappears.
As a result, it is possible to eliminate variations in the exhaust gas component emission amount when the air-fuel ratio feedback control is performed.

In addition, as shown in FIG.
Fins 34 that give a swirl flow to the exhaust gas that flows into the inner wall near 32
In addition to eliminating the directivity of the electrode surface, the inflowing exhaust gas is sufficiently mixed, and the variation in the oxygen concentration in the exhaust gas discharged from each cylinder can be eliminated, and the influence of each cylinder can be eliminated. Can be excluded. Incidentally, 33 is an exhaust gas discharge hole formed in the same manner as in the first embodiment.

Further, as shown in FIGS. 3 and 4, the exhaust introduction pipe 41 is formed into a straight cylindrical shape, and a plurality of slits having a shape in which the opening portion at the tip portion protrudes outward from the tip end as shown in the figures.
42 may be provided radially to configure the exhaust gas introducing portion. still,
Similar to the first embodiment, the exhaust gas discharge portion is formed by providing a plurality of exhaust gas discharge holes 43 along the circumferential direction on the side surface near the base end side of the exhaust gas introduction pipe 41.

With this configuration, the exhaust gas that has flowed into the exhaust gas introduction pipe 41 through the slit 42 becomes a swirl flow as in the second embodiment.
Since the protector 10 flows from the front end side toward the base end side and is discharged from the exhaust gas discharge hole 43, the exhaust gas is sufficiently mixed and the influence of each cylinder can be eliminated.

In each of the examples, an example of application to a plate-shaped zirconia oxygen sensor was shown, but two electrodes are arranged side by side on a plate-shaped insulating substrate and these electrodes are covered with a porous titania layer. It can also be applied to a titania oxygen sensor having a configuration.

<Effects of the Invention> As described above, according to the present invention, the exhaust gas is introduced by making the tip opening of the exhaust gas introduction pipe face the exhaust gas flow and introducing the exhaust gas from the protector tip side of the oxygen sensor. Since the pipe is attached, the directivity for the exhaust flow between the sensor element electrodes can be eliminated, and the oxygen sensor can exhibit a constant oxygen concentration detection performance by eliminating the variation in characteristics due to the mounting direction of the oxygen sensor. it can.

In addition, the straight cylindrical tip surface is provided with a plurality of radial slits such that the openings project outward from the tip, so that exhaust gas is introduced and the exhaust gas is introduced from the protector tip side of the oxygen sensor. Since the pipe is attached to the exhaust nut, in addition to the effect that the directivity for the exhaust flow between the sensor element electrodes can be eliminated and constant oxygen concentration detection performance can be exhibited regardless of the sensor installation direction, the exhaust gas can be swirled. It can be introduced as a flow, and by eliminating the variation in the concentration of the exhaust gas discharged from each cylinder, it has the effect of eliminating the influence between the cylinders.

[Brief description of drawings]

FIG. 1 is an oxygen sensor mounting state diagram showing a first embodiment of the present invention, FIG. 2 is a sectional view of a second embodiment of the present invention, and FIG. 3 is an external front view showing a third embodiment of the present invention. FIG. 4 is a view seen from the tip side of the exhaust introduction pipe of the third embodiment, FIG. 5 is a sectional view of a sensor element part to which the present invention is applied, and FIG. 6 is a main part of a conventional oxygen sensor. FIG. 7 is a view showing the state of attachment of a conventional oxygen sensor, FIG. 8 is a view for explaining the relationship between the direction of the oxygen sensor electrode portion and the exhaust flow, and FIG. 9 is the same as the direction of the electrode surface in the conventional example. It is a graph which shows the relationship with a nitrogen oxide discharge amount. 5 ... Sensor element part, 14 ... Exhaust nut 21,31,41 ... Exhaust gas introduction pipe, 22,23 ... Tip opening 23,33,43 ... Exhaust gas exhaust hole, 42 ... Slit

Claims (2)

[Scope of utility model registration request] 1. A mounting device for mounting an oxygen sensor for an internal combustion engine, which detects an oxygen concentration in exhaust gas by means of a plate-shaped sensor element portion exposed to the exhaust gas, to an exhaust pipe, wherein the oxygen sensor is fixed to a wall surface of the exhaust pipe. Exhaust nut,
And an exhaust introduction pipe fixed to the exhaust pipe inner end surface of the exhaust nut so as to cover the periphery of the sensor element portion, wherein the exhaust introduction pipe has a front end side of an entire opening facing the exhaust flow. An oxygen sensor mounting device for an internal combustion engine, comprising an exhaust gas introduction portion, and an exhaust gas discharge portion having a plurality of small holes along the circumferential direction on a peripheral wall near the base end side. 2. A mounting device for mounting an oxygen sensor for an internal combustion engine, which detects an oxygen concentration in exhaust gas by means of a plate-shaped sensor element portion facing the exhaust gas, to an exhaust pipe, wherein the oxygen sensor is fixed to a wall surface of the exhaust pipe. Exhaust nut,
And an exhaust introduction pipe fixed to an exhaust pipe inner end surface of the exhaust nut so as to cover the periphery of the sensor element portion, wherein the exhaust introduction pipe has a straight cylindrical shape along the sensor element portion. A plurality of slits are provided on the tip end surface thereof, each of which has a plurality of slits radially outwardly projecting toward the tip tip end, and a plurality of slits are provided along the circumferential direction on a peripheral wall near the base end side fixed to the exhaust nut. A mounting device for an oxygen sensor for an internal combustion engine, which has a structure including an exhaust gas discharge portion provided with the small holes.