JP4423309B2 - Gas sensor - Google Patents

Description

The present invention includes a protector that is used in a state exposed to a gas to be measured, such as an oxygen sensor and a NO _x sensor, and that protects a gas detection element housed in the gas from moisture contained in the gas to be measured. The present invention relates to a gas sensor.

Conventionally, a gas sensor that is attached to an internal combustion engine such as an automobile engine and detects a specific gas component in exhaust gas (a gas to be measured) has been developed. As one of them, a gas sensor (oxygen sensor) that detects a gas concentration using a solid electrolyte such as zirconia, for example, and an NO _x sensor that detects a nitrogen oxide gas concentration are known. .

  In general, this type of gas sensor has a structure in which a gas contact portion formed on the gas detection element is exposed to exhaust gas, and the gas detection element is heated to a high temperature (about 300 ° C.) using a heater. It is activated and detects the oxygen concentration in the exhaust gas.

By the way, since the gas detection element is fragile to thermal shock, if moisture in the exhaust gas adheres to the gas detection element heated to a high temperature, there is a possibility that the gas detection element may be broken due to a crack.
For this reason, a protector that covers the gas contact portion of the gas detection element is attached to the gas sensor to protect the gas detection element from water droplets.

  And this protector is equipped with the inlet and outlet of the gas to be measured on the side and bottom, and introduces the gas to be measured from the inlet of the protector and leads it to the gas detection element, where the gas component is measured in the gas detection element After that, the measurement gas is introduced and discharged such that it is discharged from the discharge port.

  By the way, the gas sensor is not necessarily installed with the central axis of the gas sensor in a fixed direction with respect to the flow direction of the gas to be measured, and is limited by the shape of the exhaust pipe and the structure around the exhaust pipe. The shaft may be tilted.

  Therefore, even if the sensor central axis of the gas sensor is inclined with respect to the flow direction of the gas to be measured, the gas detection element can be protected from the adhesion of moisture, and the gas to be measured is introduced into the protector from the discharge port. Therefore, there is a need for a gas sensor that does not impair the discharge of the gas to be measured and that has excellent responsiveness and detection accuracy for detecting the gas component of the gas to be measured.

  In order to protect the gas detection element, remove moisture contained in the gas to be measured, and introduce and discharge the gas to be measured effectively, the protector has a double-layered structure consisting of an inner cylindrical portion and an outer cylindrical portion. There is a structured gas sensor.

In a gas sensor having a double structure of a conventional protector, the side wall of the inner cylindrical part and the side wall of the outer cylindrical part are arranged coaxially via a gap, and the inlet of the gas to be measured (first measurement) is provided on these side walls. Side gas inlet and second side gas inlet) are formed. Moreover, the guide body for generating the swirl | flow which surrounds the side wall outer surface of an inner side cylindrical part is arrange | positioned at the inlet of an outer side cylindrical part. As a result, the gas to be measured introduced from the inlet of the outer cylindrical portion is separated into relatively heavy water droplets and relatively light gas components by the function of causing the swirling flow of the guide body, Then, the gas to be measured from which moisture has been removed flows from the inlet of the inner cylindrical portion into the inner cylindrical portion and is brought into contact with the gas detection element, thereby detecting a specific gas component in the measured gas. Thereafter, the gas to be measured is passed through the discharge port (first gas outlet) provided on the bottom wall of the inner cylindrical part, and discharged from the discharge port (second gas outlet) provided on the bottom wall of the outer cylindrical part. I am letting. (For example, see Patent Document 1)
Further, as a gas sensor having a double structure of the protector, the side wall of the inner cylindrical part and the side wall of the outer cylindrical part are arranged coaxially through a gap, and the tip of the inner cylindrical part is more axial than the outer cylindrical part. Some are configured to protrude. A plurality of inflow / exhaust openings for the gas to be measured are formed in the side wall of the inner cylindrical portion, the side wall of the outer cylindrical portion, the bottom wall of the inner cylindrical portion, and the like. As a result, the gas to be measured is introduced into the protector from the inflow / discharge opening, and the gas to be measured whose gas component is detected in the protector is discharged from the inflow / discharge opening to the outside of the protector. (For example, see Patent Document 2)
By the way, the gas sensor is not necessarily installed with the central axis of the gas sensor in a fixed direction with respect to the flow direction of the gas to be measured, and is limited by the shape of the exhaust pipe and the structure around the exhaust pipe. The shaft may be tilted.

For this reason, even if the sensor central axis of the gas sensor is inclined with respect to the direction in which the gas to be measured flows, the gas detection element can be protected from moisture adhesion, and the gas to be measured can be introduced into the protector and the gas sensor from the outlet There is a need for a gas sensor that does not impair the discharge of the measurement gas and has excellent responsiveness and detection accuracy for detecting the gas component of the gas to be measured.
Japanese Patent Laid-Open No. 2001-099807 (page 4-9, FIGS. 1 and 3) JP 2000-511645 (page 5-6, FIG. 1)

  However, according to the gas sensor disclosed in Patent Literature 1, the discharge port for the gas to be measured formed in the inner cylindrical portion is configured inside the outer cylindrical portion, and the discharge port provided on the bottom surface of the inner cylindrical portion. Since there is a gap from the measurement gas introduction port to the measurement gas, there is a problem in that the measurement gas in the protector becomes insufficiently substituted and the responsiveness of detecting the gas component of the measurement gas may be impaired.

  In other words, a part of the gas to be measured introduced from the inlet of the outer cylindrical part does not enter the inlet of the inner cylindrical part and passes through the gap between the side wall of the outer cylindrical part and the side wall of the inner cylindrical part. The gas to be measured discharged from the outlet of the outer cylindrical part or gas component detected and discharged from the outlet of the inner cylindrical part passes through the gap between the side wall of the inner cylindrical part and the side wall of the outer cylindrical part. By recirculating and flowing again into the inner cylindrical portion from the inlet of the inner cylindrical portion, the measurement gas in the protector may be insufficiently replaced.

  Further, according to the gas sensor disclosed in Patent Document 2, the bottom surface of the protector is provided with an inflow / exhaust port for the gas to be measured, and the gas detection element is disposed inside the protector via the bottom surface of the protector. Therefore, there is a problem that the gas to be measured containing water droplets or moisture easily flows from the inflow / exhaust port on the bottom surface of the protector, and there is a risk that water droplets or moisture adheres to the gas detection element and breaks due to cracks. there were.

  Furthermore, if the sensor central axis is tilted so that the bottom surface with the protector inflow / discharge port faces the direction of gas flow to be measured, there is a problem that gas containing water droplets or moisture easily flows from the inflow / discharge port. It was.

  The present invention has been made in view of these problems. Even when the sensor central axis of the gas sensor is inclined with respect to the direction of flow of the gas to be measured, the gas to be measured including moisture and water droplets flows into the protector. The gas detection element can be protected from moisture adhesion, the introduction and discharge of the gas to be measured in the protector is not impaired, and the gas to be measured can be satisfactorily replaced. An object of the present invention is to provide a gas sensor with excellent response and detection accuracy for detecting components.

The invention according to claim 1, which has been made to achieve the above object, includes a gas detection element that extends in the axial direction and has a gas contact portion that is brought into contact with a gas to be measured at a tip portion thereof.
A case surrounding the radial periphery of the gas detection element with the gas contact portion protruding from the tip, and a bottomed cylindrical shape fixed to the case so as to cover the gas contact portion of the gas detection element A gas sensor comprising a protector, wherein the protector includes an inner cylindrical portion, an outer cylindrical portion coaxially disposed on a side wall of the inner cylindrical portion via a gap, the inner cylindrical portion, and the outer cylindrical portion. A bottom cylindrical portion disposed on the distal end side in the axial direction from the cylindrical portion, and the inner cylindrical portion includes a cylindrical inner side wall and an inner bottom wall connected to the inner side wall, and the outer cylinder The cylindrical portion includes a cylindrical outer side wall and an outer bottom wall that is bent from the outer side wall toward the inner side wall and connected to the inner bottom wall or the inner side wall, and the bottom side cylindrical portion includes the inner bottom Axial direction from the wall or the outer bottom wall toward the tip of the protector A cylindrical bottom side wall protruding, and a the bottom side wall of the tip bottom bottom wall coupled to said protector, a edge portion or said inner sidewall of said outer bottom wall said inner bottom wall As well as connecting, the outer side wall is bent and protruded from the connecting portion toward the tip in the axial direction, this protruding portion is used as the bottom side wall, and the gas to be measured is supplied to the outer cylindrical portion. In order to introduce, a plurality of outer wall gas inlets are formed, and a plurality of inner wall gas inlets are formed on the inner side wall in order to introduce a gas to be measured into the inner cylindrical portion. A first discharge port is formed to discharge the gas to be measured from the inner cylindrical portion to the bottom cylindrical portion, and the gas to be measured is provided from the bottom cylindrical chamber to the protector on the bottom bottom wall. A second discharge port is formed to discharge outward, and the outer bottom wall Characterized in that the formation of the drain hole for discharging the accumulated water droplets to the tubular portion.

  According to the gas sensor of claim 1, even if the central axis of the gas sensor is inclined with respect to the flow direction of the gas to be measured, the gas detection element can be protected from moisture adhesion, and the gas to be measured in the protector is replaced. Therefore, it is possible to obtain a gas sensor excellent in responsiveness and detection accuracy for detecting the gas component of the gas to be measured.

That is, this gas sensor forms an inner bottom wall provided with a first discharge port for the gas to be measured and a bottom side bottom wall provided with a second discharge port for the gas to be measured, from the second discharge port. Since the gas to be measured is partitioned by the inner bottom wall so that the gas to be measured does not directly contact the gas detection element, the gas to be measured may flow into the bottom cylindrical portion from the second outlet. However, inflow into the inner cylindrical portion can be reduced. In addition, by bringing the gas flowing in from the second discharge port into contact with the inner bottom wall, the moisture contained in the gas to be measured is condensed and separated, and the gas to be measured is brought into the inner side from the first discharge port. Even if it flows into the cylindrical portion, the adhesion of moisture to the gas detection element can be reduced. In addition, a drain hole is formed in the outer bottom wall to discharge water droplets accumulated in the outer cylindrical part, so that the condensed water generated when the gas to be measured contacts the peripheral wall in the outer cylindrical part is drained. It can be removed to the outside of the protector via the hole, and water droplets can be prevented from entering the inner cylindrical portion without collecting water droplets in the outer cylindrical portion.

According to the gas sensor of the first aspect , since the bottom side wall is formed by bending the outer bottom wall, a new part and a joining process for forming the bottom side wall are not required, and productivity is reduced. It can be improved.

Next, the invention according to claim 2, in the gas sensor according to claim 1, wherein the protector, arrangement of the first outlet and the second outlet, the free positions to overlap in the axial direction of the gas sensor It was set up.

According to the gas sensor of the second aspect , the first discharge port and the second discharge port are formed so as to be shifted to a position where they do not overlap in the axial direction. The measurement gas can easily come into contact with the inner bottom wall, and the effect of preventing the measurement gas from flowing into the inner cylindrical portion can be further improved. In addition, since the gas to be measured flowing from the second discharge port easily comes into contact with the inner bottom wall, the effect of condensing and separating the moisture contained in the gas to be measured is improved, and the gas to be measured is slightly measured. Even if gas flows into the inner cylindrical portion from the first discharge port, the gas detection element can be more reliably protected without moisture adhering to the gas detection element.

Next, according to a third aspect of the present invention, in the gas sensor according to the first or second aspect, the bottom cylindrical portion is configured such that the diameter of the bottom side wall is reduced toward the bottom bottom wall. It is characterized by being formed with a taper.

According to the gas sensor of the third aspect , since the bottom side wall is formed with a taper that reduces the diameter toward the bottom side bottom wall, the gas to be measured that flows around the bottom side wall contacts the taper. By this, it flows toward the bottom side bottom wall along the taper. Then, since the flow of the gas to be measured is generated along the taper, the direction of the gas to be measured flowing so as to face the bottom wall can be avoided, so that the gas to be measured is discharged from the second outlet. Inflow can be suppressed. In addition, since the gas to be measured flowing along the taper generates a negative pressure in the vicinity of the bottom side bottom wall, the gas to be measured can be quickly discharged from the second outlet formed in the bottom side wall, and the gas to be measured in the protector can be discharged. The replacement of the measurement gas can be made better, and the response speed and detection accuracy for detecting a specific gas component in the gas to be measured can be further improved.

Next, the invention according to claim 4 is the gas sensor according to any one of claims 1 to 3 , wherein the bottom cylindrical portion extends inward to the outer wall gas introduction port. It is characterized by having attached.

According to the gas sensor of the fourth aspect , since the guide body extending inward is attached to the outer wall gas introduction port, the moisture in the measurement gas introduced from the outer wall gas introduction port is condensed and removed. The gas to be measured having a reduced specific gravity can be flowed toward the inner wall gas inlet and can be quickly introduced into the inner cylindrical portion.

  In other words, the guide body has a function of generating a swirling flow in a state in which the gas to be measured surrounds the outer peripheral surface of the inner cylindrical portion, and relatively heavy water droplets are relatively moved by the inertial force generated by the swirling flow. Separated from the light gas component, the separated water droplets are pressed against the inner peripheral surface of the outer cylindrical portion. As a result, even when water droplets are included in the gas to be measured, the water droplets do not easily enter the inside of the inner cylindrical portion, and the function of protecting the gas detection element is improved.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating a configuration of a gas sensor to which the present invention is applied, and FIG. 2 is a cross-sectional view illustrating a shape of a protector according to the present embodiment, and a cross-sectional view taken along line BB in the drawing.

  1 and 2, reference numeral 1 denotes a gas sensor. The gas sensor 1 includes a gas detection element 2 having a gas contact portion that is brought into contact with a gas to be measured, and a case 3 that holds the gas detection element 2 in a protruding state. And a bottomed cylindrical protector 4 fixed to the case 2 so as to cover the periphery of the gas detection element 2.

  The gas detection element 2 is fixed to the case 3 via a ceramic holder 62, talc powder 63, and a ceramic sleeve 64 arranged from the front end side of the case 3. An outer cylinder 65 is fixed to the outer periphery of the rear end side of the case 3 by welding or the like. Further, on the inner side of the rear end side of the outer cylinder 65, a ceramic separator 67 and a grommet 69 through which a lead wire 66 for making an electrical connection with the gas detection element 2 through the lead frame 61 is inserted are provided. Is arranged. The ceramic separator 67 is formed with a flange portion 68 projecting outward on the outer peripheral surface of the substantially center in the axial direction, and the outer support portion formed in a form in which the flange portion 68 projects inwardly in the outer cylinder 65. 70. The grommet 69 is elastically fitted inside the outer cylinder 65.

  The protector 4 includes an inner cylindrical portion 101, an outer cylindrical portion 102 coaxially disposed on a side wall of the inner cylindrical portion 101 with a gap therebetween, and an axial tip from the inner cylindrical portion 101 and the outer cylindrical portion 102. And a bottom cylindrical portion 103 disposed on the side.

The outer cylindrical portion 102, a cylindrical outer side wall 6, an outer bottom wall 11 which is connected to the inner side wall 5 and the inner bottom wall 10 below and bent toward this outer sidewall 6 to the inside side wall 5 below I have. Then, the outer bottom wall 11 is bent and projected from the connecting portion toward the tip in the axial direction, and this protruding portion is integrally formed as a bottom side wall 12 described later.

The outer side wall 6 of the outer cylindrical part 102 has an outer wall gas inlet 8 provided with a guide body 9 extending inward in order to introduce the gas to be measured into the outer cylindrical part 102. A plurality are formed at intervals of 45 ° on the circumference (see FIG. 2B). As shown in FIG. 2, the guide body 9 is formed by cutting the outer side wall 6 into a U-shape and bending the cut piece approximately 45 degrees inward with respect to the tangent line of the outer periphery of the outer side wall 6. It is formed by. The guide body 9 has a function of generating a swirling flow in a state in which the gas to be measured surrounds the outer peripheral surface of the inner side wall 5 , and the inertial force generated by the swirling flow causes a relative flow of relatively heavy water droplets. Thus, the light gas component is separated. A plurality of drain holes 16 are formed in the outer bottom wall 11 of the outer cylindrical portion 102 in order to discharge water droplets accumulated in the outer cylindrical portion 102.

  In the inner cylindrical portion 101, in order to introduce the gas to be measured around the gas detection element 2, the inner wall gas introduction port 7 in the inner side wall 5 is located closer to the case 3 than the outer wall gas introduction port 8. It is formed so as to face the gas detection element 2. The inner wall gas introduction ports 7 are arranged to be shifted by 22.5 ° in the circumferential direction with respect to the outer wall gas introduction ports 8, and a plurality of inner wall gas introduction ports 7 are formed at intervals of 45 ° in the circumference. The outer peripheral surface of the inner side wall 5 at a position facing the outer wall gas inlet 8 is formed in parallel with the outer peripheral surface of the outer side wall 6.

  A plurality of first discharge ports 14 are formed in the inner bottom wall 10 of the inner cylindrical portion 101 in order to discharge the gas to be measured from the inner cylindrical portion 101 to the bottom cylindrical portion 103. The first discharge port 14 is formed outside the second discharge port 15 so as not to overlap with a second discharge port 15 formed in the bottom side bottom wall 13 described later in the axial direction of the gas sensor 1. ing. By configuring the inner bottom wall 10 so as to partition the inner cylindrical portion 101 and the bottom cylindrical portion 103, the gas to be measured that has entered from the second discharge port 15, which will be described later, is contained in the inner cylindrical portion 101. It can be suppressed so as not to enter.

The bottom cylindrical portion 102 is formed by the bottom side wall 12 formed integrally with the outer bottom wall 11 and the bottom side bottom wall 13 connected to the tip of the bottom side wall 12 as described above. .
The bottom side wall 12 is formed with a taper so as to reduce the diameter toward the bottom side bottom wall 13, and a second exhaust for discharging the gas to be measured to the outside of the protector 4 is formed on the bottom side wall 12. The outlet 15 is formed so as not to overlap the first outlet 14 in the axial direction of the gas sensor 1.

Below, the effect of the gas sensor of embodiment which has the said structure is described.
The gas sensor according to the present embodiment includes an inner cylindrical portion 101 and a bottom cylindrical portion 103 arranged on the distal end side in the axial direction from the outer cylindrical portion 102, and the inner bottom wall 10 of the inner cylindrical portion 101 has a first inner wall 10. 1 and the second exhaust port 15 is formed in the bottom bottom wall 13 of the bottom cylindrical portion 103, so that the gas to be measured passes through the bottom cylindrical portion 103 from the second exhaust port 15. Even if it flows into the inside, the inflow to the inner cylindrical portion 101 can be reduced, and it is possible to more reliably protect moisture from coming into contact with the gas detection element accommodated in the inner cylindrical portion 101.

Further, when the gas to be measured flowing from the second outlet 15 comes into contact with the inner bottom wall 10, moisture contained in the gas to be measured is condensed and separated, so that the gas to be measured is separated from the first outlet. Even if the gas flows into the inner cylindrical portion 101 from 14, the gas detection element can be protected without moisture adhering to the gas detection element 2.

In addition, since at least one drain hole 16 is formed in the outer bottom wall 11 of the outer cylindrical portion 102, the condensed water generated when the gas to be measured comes into contact with the peripheral wall in the outer cylindrical portion 102 is treated with water. It can be removed to the outside of the protector 4 through the punching hole 16, and water droplets can be prevented from entering the inner cylindrical portion 101 without accumulating in the outer cylindrical portion 102.

  In addition, since the bottom side wall 12 of the bottom side tubular portion 103 is tapered so as to reduce in diameter toward the bottom side bottom wall 13, the gas to be measured including water droplets is discharged from the second outlet 15. The gas to be measured can be prevented from flowing in, the gas to be measured can be quickly exhausted from the second outlet 15 formed in the bottom wall 13, the gas to be measured in the protector 4 can be replaced better, and the gas to be measured It is possible to improve the response speed and detection accuracy for detecting the gas component therein.

Further, since the outer wall gas introduction port 8 is provided with a guide body 9 extending inward, the gas to be measured introduced from the outer wall gas introduction port 8 is surely provided on the outer periphery of the inner side wall 5 of the inner cylindrical portion 101. The moisture in the gas to be measured can be condensed and removed by contacting the surface. Since the gas to be measured has a reduced specific gravity by removing moisture, it can be quickly introduced into the inner cylindrical portion 101.

Next, various aspects of the gas sensor of the present invention will be described with reference to FIG. FIG. 3 is a sectional view showing the detailed shape of the protector.
The gas sensor of various modes shown in FIG. 3 is basically the same in configuration as the gas sensor 1 shown in the above embodiment, so the common components are given the same reference numerals, and detailed description is omitted. The part which becomes a characteristic is demonstrated.

The protector 30 shown in FIG. 3A includes a cylindrical outer side wall 36 and an outer bottom wall 11 formed with an insertion hole that is bent from the outer side wall 36 toward the inner side wall 35 and through which the inner side wall 35 is inserted. The inner side wall 35 protrudes from the insertion hole to the front end side, and the protruding portion serves as a bottom side wall 32, and a bottom side bottom wall 33 provided with a second discharge port is connected to the front end portion of the bottom side wall 32. The partition plate 17 having the first discharge port 34 formed in the inner cylindrical portion side wall 35 is engaged, and the partition plate 17 is used as the inner bottom wall of the inner cylindrical portion 101.

  According to the protector 30 shown in (a), since the inner side wall 35 protruding from the insertion hole of the outer bottom wall 11 to the front end side is the bottom side wall 32, a new part or The bonding process is not necessary, and productivity can be improved. The partition plate 17 can prevent the moisture from entering the inner cylindrical portion 101.

Next, the protector 40 shown in FIG. 3B is provided with a cylindrical inner side wall 45 and an inner bottom wall 10 provided with a first discharge port 14 on the inner cylindrical portion 101, and has an outer cylindrical shape. The portion 102 includes a cylindrical outer side wall 46 and an outer bottom wall 11 bent from the outer side wall 46 toward the inner side wall 36, and the end of the outer bottom wall 11 is bent to form a bottom cylindrical portion. 103 protrudes in the axial direction toward the bottom wall 43, and the protruding portion serves as a bottom side wall 42 of the bottom cylindrical portion 103. Also it has a configuration in which overlapping inner bottom wall 10 and the outer side bottom connecting plate 48 forming the first outlet 14 and overlaps the through hole 21 between the wall 11.

According to the protector 40 shown in (b), since the end of the outer bottom wall 11 of the outer cylindrical portion 102 is bent to form the bottom side wall 42 of the bottom cylindrical portion 103, the bottom side wall 42 is formed. As a result, new parts and bonding processes are not required, and productivity can be improved. Further, since the connecting plate 48 is stacked between the bottom side bottom wall 43 and the inner bottom wall 10, even if non-measurement gas containing moisture flows from the second discharge port, it enters the inner cylindrical portion 101. It can be prevented more reliably so that it does not occur.

Next, the protector 50 shown in FIG. 3C includes a cylindrical inner side wall 55 and an inner bottom wall 10 provided with a first discharge port 14 on the inner cylindrical portion 101, and the outer cylindrical portion. 102 includes a cylindrical outer side wall 56 and an outer bottom wall 54 that is bent inwardly from the outer side wall 56 and provided with a through hole 21. The through hole 21 is an inner bottom wall of the inner cylindrical portion 101. 10, the inner bottom wall 10 and the outer bottom wall 54 are overlapped so as to overlap the first discharge port 14 formed in FIG. Moreover, the bottom side tubular portion 103, a bottom side wall 52 and is formed by connecting the bottom side bottom wall 53 that attaching a second outlet 51, the outer side bottom wall edge of the bottom side wall 52 It has the structure which bent along 54 and was closely_contact | adhered.

  According to the protector 50 shown in (c), since the inner bottom wall 10 and the outer bottom wall 54 are overlapped with each other, even if a non-measurement gas containing moisture flows from the second outlet 51, the inner cylindrical portion It is possible to more surely prevent intrusion into 101.

According to the embodiment of the present invention, the protector 4 is provided with the bottom cylindrical portion 103 so that unnecessary gas does not flow into the inner cylindrical portion 101 from the second discharge port 15. Although the double structure including the bottom wall 53 and the inner bottom wall 10 is used, a multiple structure such as a triple structure may be formed by fitting a partition plate in the inner side wall 5.

  Further, according to the embodiment of the present invention, the outer wall gas introduction ports 8 are uniformly formed at intervals of 45 degrees on the outer side wall 6 of the outer cylindrical portion 102, and the guide body 9 is the end portion of the outer wall gas introduction port 8. The guide body 9 is bent at 45 ° with respect to the outer peripheral tangential direction of the outer side wall 6, but the bending angle of the guide body 9 is not limited to 45 °, depending on the application, shape, mounting structure, etc. of the gas sensor The bending angle may be obtained.

  Further, according to the embodiment of the present invention, the shape of the first outlet 14 and the second outlet 15 is a hole shape corresponding to the thickness of the inner bottom wall 10 and the bottom side bottom wall 13. This hole may be projected outward by burring or the like.

It is sectional drawing showing the structure of the gas sensor of Embodiment 1 to which this invention was applied. It is sectional drawing showing the detailed shape of the protector of the embodiment. It is sectional drawing showing the shape of the protector of the modification to which this invention was applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gas sensor, 2 ... Gas detection element, 3 ... Case, 4, 30, 40, 50 ... Protector, 5, 35, 45, 55 ... Inner side wall, 6, 36, 46, 56 ... Outer side wall, 7 ... Inner wall gas inlet, 8 ... the outer wall gas inlet, 9 ... guide member, 10 ... inner bottom wall, 11,54 ... outer bottom wall, 12, 32, 42, 52 ... bottom side wall, 13,33,43,53 ... bottom Side bottom wall, 14, 34 ... 1st discharge port, 15, 51 ... 2nd discharge port, 16 ... Drain hole, 17 ... Partition plate (inner bottom wall), 21 ... Through-hole, 47 ... Connection plate , 61 ... Lead frame, 62 ... Ceramic holder, 63 ... Talc powder, 64 ... Ceramic sleeve, 65 ... Outer cylinder, 66 ... Lead wire, 67 ... Ceramic separator, 68 ... Flange part, 69 ... Grommet, 70 ... Outer support part , 101 ... inner cylindrical portion, 102 ... outer Jo unit, 103 ... bottom cylindrical portion.

Claims (4)

A gas detection element that extends in the axial direction and has a gas contact portion that is brought into contact with the gas to be measured at the tip portion;
A case surrounding the circumference of the gas detection element in a state where the gas contact portion protrudes from the tip;
A bottomed cylindrical protector fixed to the case so as to cover the gas contact portion of the gas detection element;
A gas sensor comprising:
The protector includes an inner cylindrical portion, an outer cylindrical portion coaxially disposed on a side wall of the inner cylindrical portion via a gap, and an axially distal end from the inner cylindrical portion and the outer cylindrical portion. With the disposed bottom cylindrical portion,
The inner cylindrical portion includes a cylindrical inner side wall and an inner bottom wall connected to the inner side wall,
The outer cylindrical portion includes a cylindrical outer side wall and an outer bottom wall that is bent from the outer side wall toward the inner side wall and connected to the inner bottom wall or the inner side wall.
The bottom cylindrical portion includes a cylindrical bottom side wall protruding in an axial direction from the inner bottom wall or the outer bottom wall toward the tip of the protector, and a bottom bottom connected to the tip of the bottom side wall. With walls,
The protector connects the outer bottom wall to an edge portion of the inner bottom wall or the inner side wall, and bends and protrudes the outer side wall from the connecting portion toward the tip in the axial direction. The bottom side wall,
A plurality of outer wall gas inlets are formed in the outer side wall in order to introduce a gas to be measured into the outer cylindrical portion,
A plurality of inner wall gas inlets are formed in the inner side wall in order to introduce a gas to be measured into the inner cylindrical portion,
A first discharge port is formed in the inner bottom wall for discharging the gas to be measured from the inner cylindrical portion to the bottom cylindrical portion,
A second discharge port is formed in the bottom wall to discharge the gas to be measured from the bottom cylindrical portion to the outside of the protector,
The gas sensor according to claim 1, wherein a drain hole for discharging water droplets accumulated in the outer cylindrical portion is formed in the outer bottom wall. 2. The gas sensor according to claim 1, wherein the protector is configured such that the first discharge port and the second discharge port are disposed at a position where the first discharge port and the second discharge port do not overlap in the axial direction of the gas sensor. 3. The gas sensor according to claim 1, wherein the bottom-side tubular portion is formed by being tapered so that the bottom-side side wall is reduced in diameter toward the bottom-side bottom wall . The gas sensor according to any one of claims 1 to 3, wherein the bottom cylindrical portion is provided with a guide body extending inwardly at the outer wall gas introduction port .

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