JP4760537B2 - Gas sensor - Google Patents

Description

  The present invention relates to a gas sensor that can be used for combustion control of an internal combustion engine such as a vehicle engine.

Conventionally, there is a gas sensor 9 that is installed in an exhaust system such as an internal combustion engine of an automobile engine and detects an oxygen concentration or the like in exhaust gas (see, for example, Patent Document 1).
As shown in FIG. 10, the gas sensor 9 includes a sensor element 92 for detecting a specific gas concentration in the gas to be measured, an element side insulator 93 for inserting and holding the sensor element 92, and an element side insulator 93 being inserted. And a housing 94 for holding.
As shown in the figure, the element side insulator 93 has a stepped contact portion 930 on the outer peripheral portion 932, and an insulator receiving surface for receiving the stepped contact portion 930 on the inner side surface 942 of the housing 94. 940 is formed.

  As shown in FIG. 10, the insulator receiving surface 940 of the housing 94 and the stepped contact portion 930 of the element side insulator 93 are engaged via a packing 95. The atmosphere 95 912 at the base end side from the packing 95 and the gas side atmosphere 911 to be measured at the tip end are hermetically separated by the packing 95.

However, when the gas sensor 9 is fastened and fixed to the exhaust pipe using an impact wrench or the like as an attachment tool, excessive impact is applied to the packing 95 and its peripheral portion, and the adhesion between the element side insulator 93 and the housing 94 and the packing 95 is increased. May decrease.
To solve this problem, the opening angle of the insulator receiving surface 940 (see symbol γ in FIG. 10) is reduced to ensure the adhesion between the packing 95 and the insulator receiving surface 940, and between the packing 95 and the stepped contact portion 930. It is possible to do.

However, in this case, even if the packing 95 is disposed at a predetermined position when the gas sensor 9 is assembled, the packing 95 is displaced when the lever receiving surface 940 and the stepped contact portion 930 are engaged. There is a risk of it. Therefore, it may be difficult to ensure adhesion between the packing 95 and the insulator receiving surface 940 and between the packing 95 and the stepped contact portion 930.
As a result, it may be difficult to ensure airtightness between the atmosphere on the atmosphere side and the atmosphere on the gas side to be measured.

  In addition, it is conceivable that the shape of the packing 95 is tapered so as to adapt to the opening angle γ, but it is difficult to say that it is preferable from the viewpoint of securing production cost, production efficiency, and airtightness.

JP 2002-82085 A

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a gas sensor excellent in airtightness between the atmosphere on the atmosphere side and the atmosphere on the gas side to be measured.

A first invention includes a sensor element for detecting a specific gas concentration in a gas to be measured, an element-side insulator that holds the sensor element inside, and a housing that holds the element-side insulator inside. A gas sensor comprising:
The housing has a tool fitting portion on the outer periphery for fitting an attachment tool for attaching the gas sensor to a measurement location, and an insulator receiving surface for receiving a stepped contact portion provided on the outer peripheral portion of the element side insulator Formed on the inner surface,
The insulator receiving surface of the housing and the stepped contact portion of the element side insulator are engaged via packing,
The atmosphere on the base end side from the packing and the atmosphere on the measured gas side on the tip end are hermetically separated by the packing,
The insulator receiving surface mainly comprises a main receiving surface on which the packing is disposed and an outer receiving surface on which an outer peripheral end portion of the packing is disposed,
The main receiving surface, Ri opening angle α is 90 ° ~ 100 ° der an angle a pair of contour lines appearing in the cross section with respect to the plane including the central axis of the gas sensor,
The outer receiving surface is a gas sensor characterized in that an opening angle β, which is an angle formed by the contour line, is larger than an opening angle α of the main receiving surface.

Next, the effects of the present invention will be described.
The insulator receiving surface has an outer receiving surface on which an outer peripheral end portion of the packing is disposed, and the opening angle β of the outer receiving surface is larger than the opening angle α of the main receiving surface. That is, when the packing is disposed at the time of assembling the gas sensor, the outer peripheral end of the packing can be easily placed on the outer receiving surface.

Therefore, as in the present invention, even in the opening angle α is small again angle and 90 ° ~ 100 ° of the main receiving surface, the packing with respect to the axis of the gas sensor when disposing the packing Inclination of the shaft can be suppressed. In addition, this can prevent the packing from being displaced when the insulator receiving surface and the stepped contact portion are engaged. Therefore, the packing can be deformed while being uniformly pressed toward the distal end side so as to conform to the lever receiving surface and the stepped contact portion.
As a result, airtightness between the atmosphere on the air side and the atmosphere on the gas side to be measured can be ensured.

Further, the main receiving surface, the opening angle α is Ru 90 ° ~ 100 ° der. Thereby, the gas sensor excellent in the airtightness between air | atmosphere side atmosphere and to-be-measured gas side atmosphere can be obtained.
That is, the packing is in close contact with the insulator receiving surface and the stepped contact portion by the pressing force applied to the packing in the axial direction, and the atmosphere on the atmosphere side and the atmosphere on the gas side to be measured are separated in an airtight manner. is doing.

  The component force of the pressing force (see symbol f in FIG. 2) acts on the main receiving surface in a direction parallel to the main receiving surface and toward the radially inner side. Further, a reaction force against the component force in a direction parallel to the main receiving surface and outward in the radial direction is formed on a contact surface of the packing with the main receiving surface (see reference F in FIG. 2). Is working. And the inventor discovered that the airtightness fall resulting from the impact at the time of attachment with an attachment tool can be prevented by fully increasing the said component force and the said reaction force.

Therefore, in the present invention, the opening angle α of the main receiving surface can by be Rukoto and 90 ° ~ 100 °, to ensure the above component force and the reaction force of sufficient magnitude. That is, by sufficiently increasing the component force and the reaction force, it is possible to prevent a decrease in airtightness due to an impact at the time of attachment by the attachment tool. Therefore, it is possible to obtain a gas sensor having excellent airtightness between the atmosphere on the atmosphere side and the atmosphere on the gas side to be measured.

  As described above, according to the present invention, it is possible to provide a gas sensor excellent in airtightness between the atmosphere on the atmosphere side and the atmosphere on the gas side to be measured.

Next, as a reference invention , a sensor element for detecting a specific gas concentration in a gas to be measured, an element-side insulator that holds the sensor element inside, and a housing that holds the element-side insulator inside A gas sensor comprising:
The housing has a tool fitting portion on the outer periphery for fitting an attachment tool for attaching the gas sensor to a measurement location, and an insulator receiving surface for receiving a stepped contact portion provided on the outer peripheral portion of the element side insulator Formed on the inner surface,
The insulator receiving surface of the housing and the stepped contact portion of the element side insulator are engaged via packing,
The atmosphere on the base end side from the packing and the atmosphere on the measured gas side on the tip end are hermetically separated by the packing,
The insulator receiving surface has an opening angle of 100 ° or less, which is an angle formed by a pair of contour lines appearing in a cross section by a plane including the central axis of the gas sensor,
The radially inner end portion of the insulator receiving surface, Ru gas sensor protruding portion protruding toward the base end side than the end portion is characterized in that it is disposed adjacent the Oh.

Next, the effects of the reference invention will be described.
A protruding portion that protrudes toward the base end side from the end portion is disposed adjacent to the end portion of the insulator receiving surface. Therefore, when arranging the packing, the inner peripheral end of the packing can be brought into contact with the protruding portion. Further, this prevents the packing from being displaced due to the inner peripheral end of the packing coming into contact with the protruding portion when the insulator receiving surface and the stepped contact portion are engaged. it can.

Moreover, the opening angle of the insulator receiving surface is 100 ° or less. Therefore, similarly to the first invention (invention 1), it is possible to prevent a decrease in airtightness due to an impact at the time of attachment by the attachment tool.
As a result, airtightness between the atmosphere on the air side and the atmosphere on the gas side to be measured can be ensured.

As described above, according to the reference invention , it is possible to provide a gas sensor excellent in airtightness between the atmosphere on the atmosphere side and the atmosphere on the gas side to be measured.

In the first invention (invention 1) and the reference invention , examples of the gas sensor include an O ₂ sensor, an A / F sensor, and a NOx sensor.
From the viewpoint of familiarity between the packing and the insulator receiving surface, the packing and the stepped contact portion, productivity, and the like, the packing should be substantially flat before being assembled to the gas sensor. preferable.
In the present specification, the side where the gas sensor is installed in the exhaust pipe of an internal combustion engine of an automobile will be described as the front end side, and the opposite side as the base end side.

Further, the first invention in (Claim 1), the opening angle β of the outer receiving surface is preferably 0.99 ° to 180 ° der Rukoto (claim 2).
In this case, when the packing is disposed at the time of assembling the gas sensor, the outer peripheral end of the packing can be easily and stably placed on the outer receiving surface.
In addition, it is preferable that the said opening angle is 180 degrees from a viewpoint that the outer peripheral edge part of the said packing is mounted in the said outer receiving surface in the state which is much easier and stable.

Further, in the above-referenced invention, the protruding portion is not preferable that protrudes 0.2mm above the base end side than the radially inner end portion of the insulator receiving surface.
In this case, it is possible to sufficiently prevent the packing from being displaced due to the protruding portion when the lever receiving surface and the stepped contact portion are engaged.

Example 1
A gas sensor according to an embodiment of the present invention will be described with reference to FIGS.
The gas sensor 1 of this example includes a sensor element 2 for detecting a specific gas concentration in a gas to be measured, an element-side insulator 3 that holds the sensor element 2 on the inside, and the element-side insulator 3 on the inside. And a housing 4 for holding.

As shown in FIG. 1, the housing 4 has a tool fitting portion 41 on the outer periphery for fitting an attachment tool for attaching the gas sensor 1 to a measurement location. The tool fitting part 41 of this example has a substantially regular hexagonal outer shape, and the distance between two opposing faces among the six faces is 22 mm.
The housing 4 is formed by forming an insulator receiving surface 400 on the inner side surface 40 for receiving the stepped contact portion 300 provided on the outer peripheral portion 30 of the element side insulator 3.

As shown in FIGS. 1 to 4, the insulator receiving surface 400 of the housing 4 and the stepped contact portion 300 of the element side insulator 3 are engaged via the packing 5.
Then, the atmosphere 120 on the base end side from the packing 5 and the gas-side atmosphere 110 to be measured on the distal end side are hermetically separated by the packing 5.

The insulator receiving surface 400 mainly includes a main receiving surface 401 on which the packing 5 is disposed, and an outer receiving surface 402 on which the outer peripheral end portion 501 of the packing 5 is disposed.
The main receiving surface 401 has an opening angle α of 90 °, which is an angle formed by a pair of contour lines appearing in a cross section of a plane including the central axis M of the gas sensor 1.
The outer receiving surface 402 has an opening angle β of 180 ° and is larger than the opening angle α of the main receiving surface 401. In addition, the outer receiving surface 402 can have a length in the radial direction of the contour line (see reference numeral L1 in FIG. 2) of, for example, 0.2 mm.

  The packing 5 can be produced using, for example, nickel, a nickel alloy, or stainless steel (SUS430). Moreover, the packing 5 can set hardness to Hv100-200, for example. The packing 5 of this example has an inner diameter of 13 mm, an outer diameter of 15.5 mm, and a thickness of 0.4 mm.

  In addition to the sensor element 2, the element side insulator 3, and the housing 4, the gas sensor 1 includes a measured gas side cover 11 disposed on the front end side of the housing 4 and a base of the housing 4 as shown in FIG. And an atmosphere-side cover 12 disposed on the end side. Then, the atmosphere-side atmosphere 120 is formed inside the atmosphere-side cover 12, and the measured-gas-side atmosphere 110 is formed inside the measured-gas-side cover 11.

  When the element-side insulator 3 is assembled to the housing 4, the tip side of the element-side insulator 3 through which the sensor element 2 is inserted and held is inserted into a substantially flat and ring-shaped packing 5. Thereafter, the element side insulator 3 is inserted into the housing 4 together with the packing 5, and the base end face 52 of the packing 5 and the stepped contact portion 300 of the element side insulator 3, and the tip end face 51 of the packing 5 and the housing 4 are inserted. The insulator receiving surface 400 is brought into contact with each other.

  As shown in FIG. 1, the element side insulator 3 is pressed against the distal end side by the bent portion 44 of the housing 4 while the spring 7 is brought into contact with the base end surface of the element side insulator 3. And the housing 4 can be brought into close contact with each other via the packing 5. At this time, as shown in FIGS. 2 to 4, the substantially flat packing 5 fits in the stepped contact portion 300 and the main receiving surface 401 while the outer peripheral end portion 501 is placed on the outer receiving surface 402. It will be transformed into. In this manner, the atmosphere-side atmosphere 120 on the proximal end side from the packing 5 and the gas-to-be-measured atmosphere 110 on the distal end side are hermetically separated.

As shown in FIG. 1, the element-side insulator 3 and the sensor element 2 are hermetically sealed with a glass sealing material 6. The glass sealing material 6, together with the packing 5, hermetically separates the atmosphere-side atmosphere 120 and the measured gas-side atmosphere 110 inside the gas sensor 1.
Thus, the gas sensor 1 hermetically separates the atmosphere-side atmosphere 120 and the measured gas-side atmosphere 110 from the packing 5 and the glass sealing material 6. Thereby, the concentration of the specific gas in the gas to be measured can be accurately detected by the sensor element 2.

Next, the function and effect of this example will be described.
As shown in FIGS. 1 to 4, the insulator receiving surface 400 has an outer receiving surface 402 on which the outer peripheral end 501 of the packing 5 is arranged. The outer receiving surface 402 has an opening angle β of the main receiving surface 401. It is larger than the opening angle α. That is, when the packing 5 is disposed at the time of assembling the gas sensor 1, the outer peripheral end 501 of the packing 5 can be easily placed on the outer receiving surface 402.

Therefore, even when the opening angle α of the main receiving surface 401 is as small as 100 ° or less as in the present invention, the axis of the packing 5 is inclined with respect to the axis of the gas sensor 1 when the packing 5 is disposed. This can be suppressed. This also prevents the packing 5 from being displaced when the lever receiving surface 400 and the stepped contact portion 300 are engaged. Therefore, the packing 5 can be deformed while being uniformly pressed in a stable state toward the distal end side so as to conform to the insulator receiving surface 400 and the stepped contact portion 300.
As a result, airtightness between the atmosphere-side atmosphere 120 and the measured gas-side atmosphere 110 can be ensured.

The opening angle α of the main receiving surface 401 is 100 ° or less as shown in FIGS. Thereby, the gas sensor 1 excellent in the airtightness between the atmosphere side atmosphere 120 and the measured gas side atmosphere 110 can be obtained.
That is, the packing 5 comes into close contact with the insulator receiving surface 400 and the stepped contact portion 300 by the pressing force applied to the packing 5 in the axial direction, and the atmosphere side atmosphere 120 and the measured gas side atmosphere 110 are hermetically sealed. Are separated.

  As shown in FIG. 2, a component force f of a pressing force is applied to the main receiving surface 401 in a direction parallel to the main receiving surface 401 and inward in the radial direction. Further, a reaction force F against the component force f acts on the distal end surface 51 which is a contact surface with the main receiving surface 401 in the packing 5 in a direction parallel to the main receiving surface 401 and outward in the radial direction. is doing. And the inventor discovered that the airtightness fall resulting from the impact at the time of attachment with an attachment tool can be prevented by fully increasing the component force f and the reaction force F. FIG.

  Therefore, in this example, by setting the opening angle α of the main receiving surface 401 to 100 ° or less, the component force f and the reaction force F having a sufficient magnitude can be ensured. That is, by sufficiently increasing the component force f and the reaction force F, it is possible to prevent a decrease in airtightness due to an impact at the time of attachment by the attachment tool. Therefore, the gas sensor 1 having excellent airtightness between the atmosphere-side atmosphere 120 and the measured gas-side atmosphere 110 can be obtained.

  Further, since the opening angle β of the outer receiving surface 402 is 150 ° or more, when the packing 5 is disposed when the gas sensor 1 is assembled, the outer peripheral end portion 501 of the packing 5 can be easily and stably placed on the outer receiving surface 402. It can be mounted on. In particular, in this example, since the opening angle β is 180 °, the outer peripheral end 501 of the packing 5 can be placed on the outer receiving surface 402 in an even easier and stable manner.

  As described above, according to this example, it is possible to provide a gas sensor excellent in airtightness between the atmosphere on the atmosphere side and the atmosphere on the gas side to be measured.

( Reference Example)
In this example, as shown in FIGS. 5 to 7, a protruding portion 404 that protrudes toward the base end side from the end portion 403 is disposed adjacent to the radially inner end portion 403 of the insulator receiving surface 400. This is a reference invention example of the gas sensor 1.
And the protrusion part 404 protrudes 0.2 mm or more from the said edge part 403 of the insulator receiving surface 400 to the base end side. That is, the protrusion amount T shown in FIGS. 5 and 6 is 0.2 mm or more.
In addition, the length of the insulator receiving surface 400 in the radial direction from the end 403 to the inner peripheral portion 405 of the projecting portion 404 (see reference numeral L2 in FIG. 5) can be set to 0.5 mm, for example.

When the element-side insulator 3 is assembled to the housing 4, the element-side insulator 3 is inserted into the housing 4 together with the packing 5 as in the first embodiment. At this time, the base end surface 52 of the packing 5, the stepped contact portion 300 of the element-side insulator 3, and the tip end surface of the packing 5, while the inner peripheral end portion 502 of the packing 5 is brought into contact with the protruding portion 404 of the housing 4. 51 and the insulator receiving surface 400 of the housing 4 are brought into contact with each other.
Others are the same as in the first embodiment.

Next, the effects of the embodiment of the present invention will be described.
As shown in FIGS. 5 to 7, the end portion 403 of the insulator receiving surface 400 is adjacent to a protruding portion 404 that protrudes toward the base end side from the end portion 403. Therefore, when the packing 5 is disposed, the inner peripheral end 502 of the packing 5 can be brought into contact with the protruding portion 404. In addition, this prevents the inner peripheral end 502 of the packing 5 from coming into contact with the protruding portion 404 when the insulator receiving surface 400 and the stepped contact portion 300 are engaged to prevent the packing 5 from being displaced. Can do.
As a result, the airtightness between the air-side atmosphere 120 and the measured gas-side atmosphere 110 can be ensured as in the first embodiment.

Further, since the protruding portion 404 has the protruding amount T of 0.2 mm or more, the protruding portion 404 can sufficiently prevent the packing 5 from being displaced.
In addition, the same effects as those of the first embodiment are obtained.

(Experimental example 1)
In this example, as shown in FIG. 8, the hermetic performance of the packing 5 is examined for samples in which the opening angle β of the outer receiving surface 402 is variously changed.
In addition, the code | symbol used in this example is based on the code | symbol used in FIG.

In performing the measurement, as shown in FIG. 8, a gas sensor having a housing 4 in which the opening angle β was variously changed was prepared as a sample. That is, four types of samples having the opening angle β of 90 °, 120 °, 150 °, and 180 ° were prepared. In addition, 30 samples were prepared for each sample.
The opening angle α of the main receiving surface 401 is constant at 90 °.
Further, the length of the outer receiving surface 402 in the radial direction (see the symbol L1 in FIG. 2) was constant at 0.2 mm.
And the leakage amount in 30 samples was measured about each sample, and the maximum value and the average value were computed.

  The airtightness between the atmosphere-side atmosphere 120 and the measured gas-side atmosphere 110 in the sample was examined. In this example, for each sample, the above airtightness was evaluated in a state after the tool fitting portion 41 was rotated by an attachment tool (hereinafter referred to as after impact).

  The evaluation of the airtightness is performed by placing the sample in an airtight evaluation tester in which the chamber is set to a gas-side atmosphere to be measured having a pressure (0.4 MPa) substantially the same as the actual vehicle usage environment. It was performed by measuring the amount of leakage per unit time of gas leaking from the atmosphere to the atmosphere 120.

  In this example, after turning the tool fitting portion 41 with an impact wrench to fasten and fix each sample to a dummy jig, the sample is removed from the jig, and the state after impact is performed again with the above airtightness evaluation tester The amount of leakage was measured.

The measurement result of the leakage amount is shown in FIG. In the figure, ● represents the maximum value, and x represents the average value.
As can be seen from the figure, when the opening angle β is 150 ° or more, the leakage amount can be sufficiently reduced to 1 cc / min or less and the variation in the leakage amount (the value of ● in FIG. 8). And the difference between the values of x and x) can be sufficiently small. On the other hand, when the step angle is 90 ° or 120 °, the amount of leakage exceeds 1 cc / min, and the variation in the amount of leakage is large.

( Reference experiment example)
In this example, as shown in FIG. 9, the relationship between the protruding amount T of the protruding portion 404 and the leakage amount is examined.
The following were prepared as the above samples. That is, three types were prepared: a projection amount T of the projection 404 of 0.1 mm, a projection amount T of 0.2 mm, and a projection amount T of 0.4 mm. In addition, 30 samples were prepared for each sample.
The protrusion amount T refers to the axial length between the radially inner end 403 and the protrusion 404 of the insulator receiving surface 400.
In addition, the code used in this example is based on the code used in FIG.

Also in this example, as in Experimental Example 1, the leakage amount in 30 samples was measured for each sample, and the maximum value (● in FIG. 9) and the average value (× in FIG. 9) were calculated.
The opening angle α of the insulator receiving surface 400 is constant at 90 °.
Further, the length in the radial direction from the radially inner end 403 of the insulator receiving surface 400 to the inner peripheral portion 405 of the protruding portion 404 (see L2 in FIG. 5) was constant at 0.5 mm.
Others are the same as those of Experimental Example 1.

  The measurement results are shown in FIG. As can be seen from the figure, when the protrusion amount T is 0.2 mm or more, the leakage amount can be sufficiently reduced to 1 cc / min or less, and the variation in the leakage amount ( The difference between the value and the value of x can also be made sufficiently small.

FIG. 3 is a cross-sectional explanatory view of a gas sensor in the first embodiment. Explanatory sectional explanatory drawing which shows the arrangement | positioning state of packing, the step-shaped contact part, and an insulator receiving surface in Example 1. FIG. Explanatory cross-section explanatory drawing which shows the state before assembling packing between a step-shaped contact part and an insulator receiving surface in Example 1. FIG. Explanatory cross-section explanatory drawing which shows the state after assembling packing between the step-shaped contact part and an insulator receiving surface in Example 1. FIG. Definitive Reference Example, enlarged cross-sectional view showing the arranged state between the packing and the stepped abutting portion and the insulator receiving surface. Definitive Reference Example, enlarged cross-sectional view showing a state before assembled between the stepped abutting portion and the insulator receiving surface packing. Definitive Reference Example, enlarged cross-sectional view showing a state after assembling between the stepped abutting portion and the insulator receiving surface packing. The plot figure which shows the relationship between the opening angle of an outer receiving surface in Example 1 of an experiment, and the amount of leaks. Definitive reference real Kenrei, plot showing the relationship between the projecting amount and the amount of leakage. Sectional explanatory drawing of the gas sensor in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas sensor 110 Measuring gas side atmosphere 120 Air | atmosphere side atmosphere 2 Sensor element 3 Element side insulator 30 Outer peripheral part 300 Step-shaped contact part 4 Housing 40 Inner side surface 400 Insulator receiving surface 401 Main receiving surface 402 Outer receiving surface 41 Tool fitting Part 5 Packing

Claims (2)

A gas sensor having a sensor element for detecting a specific gas concentration in a gas to be measured, an element side insulator that holds the sensor element inside, and a housing that holds the element side insulator inside,
The housing has a tool fitting portion on the outer periphery for fitting an attachment tool for attaching the gas sensor to a measurement location, and an insulator receiving surface for receiving a stepped contact portion provided on the outer peripheral portion of the element side insulator Formed on the inner surface,
The insulator receiving surface of the housing and the stepped contact portion of the element side insulator are engaged via packing,
The atmosphere on the base end side from the packing and the atmosphere on the measured gas side on the tip end are hermetically separated by the packing,
The insulator receiving surface mainly comprises a main receiving surface on which the packing is disposed and an outer receiving surface on which an outer peripheral end portion of the packing is disposed,
The main receiving surface, Ri opening angle α is 90 ° ~ 100 ° der an angle a pair of contour lines appearing in the cross section with respect to the plane including the central axis of the gas sensor,
The gas sensor according to claim 1, wherein the outer receiving surface has an opening angle β, which is an angle formed by the contour line, larger than an opening angle α of the main receiving surface. In claim 1, the opening angle β of the outer receiving surface, the gas sensor, wherein 0.99 ° to 180 ° der Rukoto.

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