JP2009180634A - Plate-like sensor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate-like sensor element capable of easily sealing a fixed portion without using a filler when it is used by fixing a housing, and of easily positioning the sensor when it is fixed to a housing. <P>SOLUTION: The plate-like sensor element 1 includes: a plate-like sensor element body 3 having a plate-like ceramics substrate; and a ring-like sealing section 4 arranged so as to surround a part of the sensor element body 3. The sensor element body 3 has a sensor portion 5 between a position at which the sealing section 4 is arranged and an end 6 of it. The material of the sealing section 4 is ceramics, and the sensor element body 3 and the sealing section 4 are integrally formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plate-like sensor element, and more specifically, when used by being fixed to a housing or the like, it is possible to easily seal the fixed portion without using a filler, The present invention relates to a plate sensor element that can be easily positioned when fixed to a housing or the like.

In order to detect dust and other particulate matter contained in incineration exhaust gas generated during incineration of automobile exhaust gas and waste, in order to detect NO _x , CO and HC, etc. in the exhaust gas, Various sensors are used to detect other substances such as O _{2 in} various gases.

  These sensors usually have a structure in which a sensor element is attached to a casing, a housing, and the like, and is attached to a pipe or the like using the casing or the like (see, for example, Patent Documents 1 and 2). Moreover, as a sensor element, the sensor element of the simple structure where the electrode for sensors etc. was embed | buried in the plate-shaped ceramic base material is disclosed (for example, refer patent document 3). Such a plate-like sensor element is excellent in mechanical strength, heat resistance, thermal shock resistance, corrosion resistance, and the like.

The plate-like sensor element is directly inserted into a housing or the like and fixed and used in a state where it is inserted up to a predetermined position. However, it is necessary to use a jig or the like to fix it at an accurate position when positioning. There is a problem that a complicated operation is required. Further, when fixing the plate-shaped sensor element, the portion for fixing the plate-shaped sensor element to the housing or the like (fixed portion) is filled with a filler such as glass or talc so as to isolate the gas atmosphere to be measured from the atmosphere. There is a problem that a complicated operation is required.
JP 2000-121599 A JP 2000-314715 A JP 57-22546 A

  When glass is used as a filler, problems such as cracking may occur when the plate-like sensor elements (plate-like sensor elements), glass, and other members used for fixing are greatly different in thermal expansion coefficient. Further, when talc is used as a filler, there are problems that the cost of talc is high and the number of man-hours such as talc calcination and assembly is increased.

  The present invention has been made in view of the above problems, and can be used to easily seal a fixed portion without using a filler when used in a housing or the like, Furthermore, the present invention provides a plate-like sensor element that can be easily positioned when fixed to a housing or the like.

  In order to solve the above problems, the following plate sensor elements are provided by the present invention.

[1] A plate-shaped sensor element main body having a plate-shaped ceramic substrate, and a ring-shaped sealing portion disposed so as to surround a part of the sensor element main body, There is a sensor part between the position where the sealing part is disposed and one end part, and the material of the sealing part is ceramic, and the sensor element body and the sealing part are integrally formed. The formed plate sensor element.

[2] The material of the ceramic substrate is at least one selected from cordierite, alumina, zirconia, titania, silicon nitride, silicon carbide, and ferrite, and the material of the sealing portion is cordierite, alumina, zirconia. The plate-like sensor element according to [1], which is at least one selected from titania, silicon nitride, spinel, silica, and mullite.

[3] The plate-like sensor element according to [1] or [2], which is formed by firing a green sheet laminate having a plurality of tape-shaped ceramic green sheets.

[4] The sealing portion has a sealing surface facing the sensor portion side and in contact with the outer peripheral surface of the sensor element main body, and the outer peripheral surface of the sensor element main body in contact with the sealing surface and the sealing surface The plate-shaped sensor element according to any one of [1] to [3], in which an angle between the first and second is 90 to 135 °.

[5] The plate-like sensor element according to [4], wherein the width of the sealing surface is 1 to 10 mm over the entire circumference.

  According to the plate-like sensor element of the present invention, the material of the sealing portion is ceramic, and is a material excellent in mechanical strength and the like. As a result, when the plate-shaped sensor element is fixed to the housing or the like, even if the sealing portion is strongly pressed against the housing or the like via a sealing ring or the like, the sealing portion is not damaged, and therefore the sensor element main body is unnecessary. By pressing strongly only the sealing portion without applying pressure, a gap through which gas flows can be eliminated, and the fixed portion can be easily sealed without using a filler. Furthermore, since the sensor element body and the sealing portion are integrally formed, if the sealing portion is pressed firmly and fixed, the sensor element body is also fixed, and the sealing portion and the sensor element body may be displaced. , Never come off. In addition, since the sensor element body and the sealing portion are integrally formed, positioning when fixing to the housing or the like can be easily performed.

  Hereinafter, the best mode for carrying out the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the following embodiment and does not depart from the spirit of the present invention. Therefore, it should be understood that design changes, improvements, and the like can be made as appropriate based on ordinary knowledge of those skilled in the art.

(1) Plate sensor element:
FIG. 1 is a perspective view showing an embodiment of the plate sensor element of the present invention. As shown in FIG. 1, the plate-like sensor element 1 of the present embodiment is disposed so as to surround a plate-like sensor element main body 3 having a plate-like ceramic substrate 2 and a part of the sensor element main body 3. The sensor element body 3 has a sensor part 5 between the position where the sealing part 4 is disposed and one end part 6. The material is ceramic, and the sensor element body 3 and the sealing portion 4 are integrally formed. A portion having the sensor portion 5 from the position where the sealing portion 4 is disposed in the sensor element body 3 to one end portion 6 is a portion to be inserted into a housing or the like.

  The sensor element body 3 constituting the plate sensor element 1 of the present embodiment has a plate-shaped ceramic substrate 2 and has a sensor portion 5 between the sealing portion 4 and one end portion 6. is there. The plate-like ceramic substrate 2 is made of ceramic and has excellent heat resistance, thermal shock resistance, corrosion resistance, electrical insulation, mechanical strength, cordierite, alumina, zirconia, titania, silicon nitride, silicon carbide, and the like. It is preferably at least one selected from ferrite, and among these, cordierite is more preferable from the viewpoint of excellent mechanical strength and electrical insulation. Since the ceramic base material 2 is made of such a material, the plate sensor element is fixed to the housing or the like by inserting the portion having the sensor portion of the plate sensor element into the housing or the like, and fixing the plate sensor element. When using a plate sensor element by inserting a housing or the like into a hole for inserting a housing or the like formed in an exhaust gas pipe or the like, even if the plate sensor element is in direct contact with high temperature exhaust gas, It can be prevented from being damaged or corroded.

  The size of the sensor element body 3 is not particularly limited, but is preferably about 50 mm × 5 mm × 1 mm to 100 mm × 10 mm × 3 mm (length × width × thickness). Moreover, the length L from the sealing part 4 to the one end part 6 is preferably about 20 to 40 mm.

The sensor unit 5 formed in the sensor element body 3 is a part that detects a target substance, for example, a part that detects particulate matter, O ₂ , NO _X , and the like in exhaust gas. The configuration of the sensor unit 5 is not particularly limited, and a known configuration that can detect a target substance can be employed. For example, when detecting particulate matter, a cavity is formed in the sensor unit 5, electrodes are disposed in the cavity and inside the ceramic substrate 2, and the flow rate is calculated by attaching particulate matter to the electrode. Etc. It is preferable that an electrical wiring passing through the inside of the sensor element main body for connecting to an external device is appropriately connected to the electrode.

  The sealing part 4 which comprises the plate-shaped sensor element 1 of this embodiment is a part formed in the ring shape arrange | positioned so that a part of sensor element main body 3 may be surrounded. As shown in FIG. 1, “dispose so as to surround a part of the sensor element body 3” means that one end surface (the end surface of one end portion 6) 7 a and the other end surface are opposite to each other. The sensor element is arranged in a ring shape on a belt-like portion (a part of the outer peripheral surface) that goes around in the direction in which the four outer peripheral surfaces are connected along the four outer peripheral surfaces excluding the end face 7b positioned. The sealing part 4 is formed in the main body 3 like a bowl. The direction connecting the one end 6 and the end (the other end 8) located on the opposite side of the one end 6 is preferably the longitudinal direction of the sensor element body 3. The sealing portion 4 is formed integrally with the sensor element body 3. Therefore, the sealing part 4 is formed at a desired position of the sensor element body 3, and the length L from the position where the sealing part 3 is disposed to one end part 6 is set to a desired length. When the sensor element is fixed to a housing or the like, the sensor element main body 3 can be easily positioned (determination of the insertion depth) by the sealing portion 3, and the sensor element main body can be a desired length. 3 can be protruded from the housing or the like.

  As shown in FIG. 1, the sealing portion 4 preferably has a sealing surface 4 a that faces the sensor portion 5 side and contacts the outer peripheral surface of the sensor element body 3. When "the sealing surface faces the sensor part", when the sensor element body is divided into two parts with the sealing part as a boundary, one of the two sensor element bodies is sealed The other side is the side where the sealing surface does not face (the side of the sealing part facing away from the sealing surface), and among these, the sealing surface of the sensor element body faces It means that there is a sensor part on the side. In the sealing portion 4, the sealing surface 4 a is a surface (sealing portion contact surface 16 ( 5)) through a sealing ring 11 (see FIG. 5) to seal between the plate sensor element 1 and the piping. The angle θ between the sealing surface 4a shown in FIG. 1 and the outer peripheral surface of the sensor element body 3 in contact with the sealing surface 4a is preferably 90 to 135 °, and preferably 90 to 120 °. Further preferred is 90 °. By setting the angle θ to such a range, the sealing portion 4 can be pressed more strongly and effectively on the surface where the sealing portion 4 formed on the housing or the like abuts, and more effectively plate-like It is possible to seal between the sensor element and the housing. When the angle θ is less than 90 ° or more than 135 °, the sealing portion 4 may be stronger and more difficult to press effectively due to the surface on which the sealing portion 4 formed on the housing or the like comes into contact. In addition, the width (the width of the sealing surface) W of the sealing surface 4a is preferably 3 to 10 mm, and more preferably 4 to 7 mm over the entire circumference. Here, “over the entire circumference” means “in any part of the circumference of the ring-shaped sealing portion 4 along the ring shape”. The width W of the sealing surface is the distance from the outer peripheral surface (four outer peripheral surfaces) of the sensor element body to the corresponding outer peripheral portion of the sealing surface (in contact with each outer peripheral surface) (the outer peripheral portion of the sealing surface) The length of the perpendicular line when the perpendicular line is dropped on the outer peripheral surface of the sensor element body with which the sealing surface is in contact. Since the width W of the sealing surface is within such a range, the sealing portion 4 can be more strongly and effectively pressed against the surface that contacts the sealing portion 4 formed on the housing or the like. It is possible to more effectively seal between the plate sensor element and the housing. When the width W of the sealing surface is smaller than 3 mm, the sealing surface becomes small, so that the sealing portion 4 is strongly and effectively pressed against the surface on which the sealing portion 4 formed on the housing or the like comes into contact. There are things you can't do. Further, if the width W of the sealing surface is larger than 10 mm, the sealing surface becomes unnecessarily large, and the surface on which the sealing portion 4 formed on the housing or the like abuts and the surrounding structure are unnecessary. There is a need to make it bigger.

  It is preferable that the sealing part 4 has the sealing part back surface 4b on the opposite side to the sealing surface 4a. The angle between the sealing portion back surface 4b and the outer peripheral surface of the sensor element body 3 in contact with the sealing portion back surface 4b is preferably 90 to 135 °, more preferably 90 to 120 °, and 90 It is particularly preferable that the angle is. By setting the angle θ in such a range, when the plate sensor element is fixed to the housing or the like, a predetermined member is pressed against the sealing surface 4a and the sealing portion back surface 4b, and the sealing portion 4 is pressed. Can be effectively fixed by being pressed so as to be sandwiched between the members, and it is possible to more effectively seal between the plate-like sensor element and the pipe or the like. Here, the “predetermined member” refers to, for example, the sealing ring 11 and the fixing member 14 shown in FIG. When the angle θ is less than 90 ° or more than 135 °, the sealing portion 4 may be stronger and more difficult to be pressed effectively due to the surface on which the sealing portion 4 formed on the pipe or the like comes into contact. Moreover, it is preferable that the width | variety (width | variety of a sealing part back surface) of the sealing part back surface 4b is 3-10 mm over a perimeter, and it is still more preferable that it is 4-7 mm. If the width of the back surface of the sealing portion is smaller than 3 mm, it is difficult to increase the pressing force from the back surface side of the sealing portion, so that the sealing portion 4 is brought into contact with the sealing portion 4 formed on the housing or the like. In addition, it may be difficult to press strongly and effectively. Further, if the width of the back surface of the sealing part is larger than 10 mm, the sealing part becomes unnecessarily large, and the structure for fixing the sealing part 4 formed on the housing or the like must be unnecessarily large. There are things that must be done.

  The outer periphery of the cross section perpendicular to the “direction connecting one end 6 of the sensor element body 3 and the end 8 on the opposite side (the other end) 8” of the sealing element 4 of the sealing portion 4 The shape is not particularly limited, but is preferably rectangular as shown in FIG. 1, and is also preferably circular as shown in FIG. Further, the shape may be a polygon such as a triangle or a pentagon, or an ellipse. FIG. 2 is a perspective view showing another embodiment of the plate sensor element of the present invention. In FIG. 2, a plate sensor element 101 is formed by disposing a sealing portion 104 on a sensor element body 103. Further, like the plate-like sensor element 201 shown in FIG. 3, the sealing portion surrounds from the end opposite to the one end 206 of the sensor element body 203 to a predetermined position of the sensor element body 203. Thus, the sealing portion 204 may be disposed. FIG. 3 is a perspective view showing still another embodiment of the plate sensor element of the present invention.

  Further, the length of the sealing portion 4 in the “direction in which the one end 6 and the other end 8 of the sensor element body 3 are connected” is not particularly limited, but is preferably 50 to 100 mm, and preferably 60 to 80 mm. Further preferred is 60 to 70 mm. If it is shorter than 50 mm (thin), the strength may be low. If it is longer than 100 mm (thick), the distance from the sealing portion 4 to the sensor portion 5 cannot be sufficiently secured, and the plate-like sensor element is connected to piping, etc. When it is fixed to, it may be difficult to arrange the sensor unit 5 at an optimal position in the pipe or the like.

  The material of the sealing portion 4 is ceramic, and is selected from cordierite, alumina, zirconia, titania, silicon nitride, spinel, silica, and mullite that are excellent in heat resistance, thermal shock resistance, corrosion resistance, mechanical strength, and the like. At least one kind is preferred, and among these, cordierite is more preferred from the viewpoint of excellent thermal shock resistance and electrical insulation. Moreover, it is preferable that the sealing part 4 and the sensor element main body 3 are similar materials, and it is still more preferable that the sealing part 4 and the sensor element main body 3 are the same material. Here, “the materials are similar” means that one thermal expansion coefficient is in a range of 0 to 5% with respect to the other thermal expansion coefficient. Since the material of the sealing part 4 and the material of the sensor element body 3 are the same, the thermal expansion coefficients of the sealing part 4 and the sensor element body 3 are the same, and damage due to thermal shock can be prevented.

  The plate sensor element of the present embodiment is preferably formed by firing a green sheet laminate 21 having a plurality of tape-shaped ceramic green sheets 22 as shown in FIG. FIG. 4 is a perspective view showing a green sheet laminate formed in the manufacturing process of the plate sensor element of the present embodiment. In the green sheet laminate 21, it is preferable that electrodes or wiring for detecting particulate matter or the like be printed on the ceramic green sheet 22.

(2) Manufacturing method of plate sensor element:
Next, the manufacturing method of the plate-shaped sensor element of this invention is demonstrated.

  The manufacturing method of one embodiment of the plate-like sensor element of the present invention produces a plurality of ceramic green sheets, and arranges electrodes and wirings for detecting particulate matter etc. at predetermined positions of predetermined ceramic green sheets, A plurality of ceramic green sheets including the ceramic green sheets on which electrodes and wirings are arranged are laminated to produce a green sheet laminate 21 as shown in FIG. 4, and the obtained green sheet laminate is fired to obtain a plate. A method of forming a sensor element is preferable. According to this manufacturing method, a tape-shaped ceramic green sheet is laminated, and the sealing portion and the sensor element main body are integrally fired to produce a plate-shaped sensor element. A plate-like sensor element in which the sensor element body and the sealing portion are integrally formed can be manufactured.

  Tape-shaped ceramic green sheets are prepared by mixing ceramic raw materials and binders, plasticizers, dispersants, dispersion media, etc. into slurry-shaped molding raw materials, which are formed into tape-shaped green sheets by the doctor blade method etc. It is. Examples of the ceramic raw material include alumina, zirconia, cordierite, titania, silicon nitride, silicon carbide, and various ferrites. In addition, examples of the raw material constituting the portion corresponding to the sealing portion in the ceramic green sheet include cordierite, alumina, zirconia, titania, silicon nitride, spinel, silica, mullite and the like. Further, the thickness of the tape-like green sheet is preferably 10 to 500 μm, and more preferably 60 to 300 μm. By setting the thickness of the tape-like green sheet within such a range, there is an advantage of improved handling properties.

  The binder is not particularly limited, and either an aqueous binder or a non-aqueous binder may be used. As the aqueous binder, methyl cellulose, polyvinyl alcohol, polyethylene oxide or the like can be suitably used, and as the non-aqueous binder, polyvinyl butyral, Acrylic resins, polyethylene, polypropylene, and the like can be suitably used. Examples of the acrylic resin include (meth) acrylic resin, (meth) acrylic acid ester copolymer, acrylic acid ester-methacrylic acid ester copolymer, and the like.

  The addition amount of the binder is preferably 3 to 20 parts by mass, and more preferably 6 to 17 parts by mass with respect to 100 parts by mass of the ceramic raw material. By setting it as such binder content, it becomes possible to prevent generation | occurrence | production of a crack etc., when shape | molding a slurry-like shaping | molding raw material and shape | molding a green sheet, and when drying and baking.

  As the plasticizer, glycerin, polyethylene glycol, dibutyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, or the like can be used.

  The addition amount of the plasticizer is preferably 30 to 70 parts by mass and more preferably 45 to 55 parts by mass with respect to 100 parts by mass of the binder. When the amount is more than 70 parts by mass, the green sheet becomes too soft and may be easily deformed in the process of processing the sheet. When the amount is less than 30 parts by mass, the green sheet becomes too hard and cracks are generated only by bending. Handling characteristics may deteriorate.

  As the dispersant, an anionic surfactant, a wax emulsion, pyridine, or the like can be used in an aqueous system, and a fatty acid, a phosphate ester, a synthetic surfactant, or the like can be used in a non-aqueous system.

  The dispersant is preferably 0.5 to 3 parts by mass, more preferably 1 to 2 parts by mass with respect to 100 parts by mass of the ceramic raw material. When the amount is less than 0.5 parts by mass, the dispersibility of the ceramic raw material may be lowered, and a crack or the like may occur in the green sheet. If the amount is more than 3 parts by mass, the dispersibility of the ceramic raw material remains unchanged, and impurities during firing increase.

  As the dispersion medium, water, an organic solvent, or the like can be used. The dispersion medium is preferably 50 to 200 parts by mass, more preferably 75 to 150 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  The slurry-like forming raw material is preferably prepared so as to be defoamed by stirring under reduced pressure before forming and further to have a predetermined viscosity. The viscosity of the slurry-like molding material obtained in the preparation of the molding material is preferably 2.0 to 6.0 Pa · s, more preferably 3.0 to 5.0 Pa · s, 3.5 It is especially preferable that it is -4.5 Pa.s. Adjusting the viscosity range in this way is preferable because the slurry can be easily formed into a sheet (tape). If the slurry viscosity is too high or too low, molding may be difficult. The viscosity of the slurry is a value measured with a B-type viscometer.

  As shown in FIG. 4, the shape of the tape-shaped ceramic green sheet obtained by forming the slurry-like forming raw material forms a portion 23 corresponding to the sensor element body and a portion 24 corresponding to the sealing portion. It is preferable to be formed. The magnitude | size is not specifically limited, It can be set as the magnitude | size suitable for manufacturing a desired plate-shaped sensor element.

  For ceramic green sheets in which electrodes and wiring for detecting particulate matter etc. are arranged at predetermined positions, for example, after forming a tape-shaped ceramic green sheet with a rectangular planar shape, the electrodes and wiring are printed by the above method. It is preferable to make it. For example, it is preferable to use Pt zirconia (a mixture of platinum and zirconia for printing) as the electrode. Further, it is preferable to use tungsten or a mixture of tungsten and a ceramic material as the wiring.

  When the tape-shaped ceramic green sheets are laminated to form a green sheet laminate, it is preferable that the tape-shaped ceramic green sheets are stacked and bonded together by pressure. Uniaxial pressurization, hydrostatic pressure pressurization, etc. can be used for pressurization. It is also preferable to perform thermocompression bonding by heating the tape-shaped ceramic green sheet during pressurization. It is further preferable to form an adhesive layer between the sheets and press-bond them.

  When the green sheet laminate obtained by the above method is integrally fired, it is preferably heated at 1000 to 1800 ° C. for 1 to 100 hours. Thereby, the plate-shaped sensor element of this invention can be obtained. As the firing apparatus, it is preferable to use a combustion furnace, an electric furnace, or the like.

(3) Plate sensor element fixing method:
Next, a method of fixing the plate sensor element of the present embodiment to a housing or the like and fixing the housing having the plate sensor element fixed to a pipe or the like will be described.

  FIG. 5 shows that the plate-like sensor element 1 of the present embodiment is inserted and fixed in the housing 20, and the housing 20 to which the plate-like sensor element 1 is fixed is fixed to the pipe 13 while being inserted into the hole 13 a of the pipe 13. It is sectional drawing cut | disconnected by the plane containing the center axis | shaft of the plate-shaped sensor element 1 and the distribution direction f of the fluid which shows a state. The flow direction f indicates the flow direction of the fluid flowing inside the pipe 13. The housing 20 includes a cylindrical housing main body 20a in which the through-hole 17 is formed, and sealing rings 11 and 12 and a fixing member 14 arranged inside the cylinder of the housing main body 20a. The housing main body 20a is formed so that one end side in the central axis direction is inserted into a hole such as a pipe. In the present embodiment, as shown in FIG. 5, the housing body 20a is preferably threaded into a portion to be inserted into a pipe or the like, and has a screw portion 20b. In order to rotate the housing 20 with a tool or the like and fix it to a pipe or the like with the screw portion 20b, it is preferable that the cross section perpendicular to the central axis direction has a hexagonal portion 20c. By having the hexagonal portion 20c, a tool such as a spanner or a monkey can be fitted into the hexagonal portion and the housing 20 can be rotated. The shape of the portion corresponding to the hexagonal portion is not limited to the hexagonal shape, as long as the housing 20 can be rotated by fitting a tool or the like to the portion or holding the portion by a tool or the like. Further, the method of fixing the housing 20 to the pipe is not limited to a method using a screw portion, and any method such as a flange type or a spring type may be used.

  The inner wall of the through hole 17 of the housing body 20 a is preferably formed with a sealing surface of the sealing portion of the plate sensor element 1 and a sealing portion contact surface 16 that contacts with the sealing ring 11. . As shown in FIG. 5, the sealing portion contact surface 16 is a plane that is formed near the end of the housing main body 20a on the side where the screw portion 20b is formed and that is orthogonal to the central axis of the housing main body 20a. It is preferable. Here, “near the end” means a range of 3 to 10 mm from the end of the housing main body 20a. The size of the opening of the through hole 17 on the end surface of the housing main body 20a on the side where the screw portion 20b is formed is preferably a size corresponding to 130 to 150% of the width of the sensor element main body. It is preferable that a “caulking claw portion 15” for caulking and fixing the sealing portion of the plate sensor element is formed at the end of the housing body 20a on the side where the hexagonal portion 20c is formed. Then, the gap between the plate sensor element 1 and the housing 20 is pressed by pushing the sealing part of the plate sensor element 1 inside the through hole 17 of the housing 20 by tilting the caulking claw portion 15 inward. Is preferably sealed. Thereby, it is possible to easily seal the fixed portion without using a filler.

  When the plate sensor element 1 is fixed in the housing 20, as shown in FIG. 5, the sealing ring 11 is disposed on the sealing portion contact surface 16 of the housing body 20a, The plate-like sensor element 1 is arranged so that the sealing surface 4a comes into contact with the sealing ring 11, the fixing member 14 is arranged so as to cover the sealing portion 4 from above the plate-like sensor element 1, and further, the fixing member It is preferable to arrange the sealing ring 12 from above 14. Then, it is preferable that the fixing portion is sealed by tilting the caulking claw portion 15 so as to be pressed from above the sealing ring 12 and the plate sensor element 1 is fixed in the housing 20. When the plate sensor element 1 is arranged in the housing 20, the plate sensor element 1 is arranged in the housing 20 so that the end on the side where the sensor part is formed is inserted into the through hole of the housing 20. It is preferable. In order to stably fix the plate sensor element, it is preferable to use a fixing member. However, the plate sensor element may be fixed by pressing the sealing portion with a caulking claw portion or the like without using the fixing member. Good. FIG. 5 shows a state before caulking by the caulking claw portion 15. Here, the fixed portion is a portion including a through hole, a plate sensor element, and a member used for fixing the plate sensor element when the plate sensor element is inserted and fixed in a through hole formed in a housing or the like. In other words, sealing the fixed part means filling a gap between the through hole formed in the housing or the like and the plate sensor element so that gas does not flow through the through hole. Moreover, since the sealing part 4 is integrally disposed at a predetermined position of the sensor element body 3, the plate-like sensor element can be easily positioned.

  When the housing 20 to which the plate sensor element 1 is fixed is fixed to the pipe, as shown in FIG. 5, a hole (pipe hole) 13a is formed through the pipe 13 from the outer wall surface 19 side to the inner wall surface 18 side. Then, a screw part corresponding to the screw part 20b of the housing 20 is formed on the inner wall surface of the pipe hole 13a, and the screw part 20b of the housing 20 is fixed by screwing into the screw part formed in the pipe hole 13a. Is preferred. By fixing the housing 20 to the pipe 13 or the like with a screw, the housing 20 and the pipe 13 or the like can be sealed without a gap.

  The material of the sealing rings 11 and 12 is not particularly limited, but nickel or the like can be used. The material of the fixing member 14 is not particularly limited, but stainless steel or the like can be used. The shape of the sealing ring 11 is not particularly limited, but is preferably a shape that can be disposed on the sealing portion abutting surface 16 and that can satisfactorily seal between the sealing surface 4 a of the plate sensor element 1. The shape of the fixing member 14 is not particularly limited, but is preferably a ring shape that is placed on a surface opposite to the sealing surface 4 a of the sealing portion 4. The outer peripheral shape of the fixing member 14 is preferably the same as the outer peripheral shape of the surface on the opposite side to the sealing surface 4 a of the sealing portion 4.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of molding raw materials)
Zirconia is used as a ceramic raw material, polyvinyl butyral is used as a binder, dibutyl phthalate is used as a plasticizer, polyno is used as a dispersant, and mixed in an alumina pot together with an organic solvent as a dispersion medium. A shaped molding material was prepared. The amount of each raw material used was 7.6 parts by mass of binder, 4 parts by mass of plasticizer, 0.75 parts by mass of dispersant, and 72 parts by mass of dispersion medium with respect to 100 parts by mass of alumina.

  Next, the obtained slurry-like forming raw material for green sheet production was stirred under reduced pressure to defoam, and prepared to have a viscosity of 4 Pa · s. The viscosity of the slurry was measured with a B-type viscometer.

(Molding)
Next, the slurry-like forming raw material obtained by the above method was formed into a sheet using a doctor blade method to obtain a plurality of ceramic green sheets. At this time, a plurality of ceramic green sheets were obtained so as to obtain a green sheet laminate having a shape as shown in FIG. The thickness of the ceramic green sheet was 250 μm.

The resulting surface of the ceramic green sheet, for forming the NO _X sensor, to form the electrodes and wirings. A conductive paste for forming each electrode and wiring to be arranged was printed on the surface of the ceramic green sheet by using screen printing to form electrodes and wirings having a predetermined shape.

  Next, the ceramic green sheets were pressure-laminated using a heatable uniaxial press to obtain a green sheet laminate shown in FIG. 4 in which the ceramic green sheets were laminated.

(Baking)
The obtained green sheet laminate was dried at 120 ° C. and fired at 1500 ° C. to produce a plate sensor element. The obtained plate-like sensor element has a sensor element body having a rectangular parallelepiped of 6.8 cm × 0.45 cm × 0.15 cm, and has a length L from the position where the sealing portion is disposed to one end portion. (See FIG. 1) was 1.5 cm, the width W (see FIG. 1) of the sealing surface was 0.2 cm, and the length X (see FIG. 1) of the sealing portion was 0.4 cm. . The width W of the sealing surface was the same value over the entire circumference as shown in FIG. Further, the angle θ (see FIG. 1) between the sealing surface and the outer peripheral surface of the sensor element body in contact with the sealing surface is 90 °, and the sensor element in contact with the sealing portion back surface and the sealing portion back surface The angle with the outer peripheral surface of the main body was 90 °. Moreover, the outer peripheral shape of the cross section of the sealing part was a rectangle.

(Sealed state evaluation)
The plate sensor element is attached to the housing 20 as shown in FIG. 5 with a torque of 3 to 5 Nm. Then, the housing 20 is screwed into a stainless steel plate in which a through hole is formed, and 0.4 MPa air is blown to the sensor part (gas detection part) side of the plate-like sensor element, so that the sensor part of the housing 20 protrudes. The pressure side is pressurized, and the amount of air leak to the lead side (the side where the end portion where the sensor portion of the plate-like sensor element is not formed protrudes) is measured. The amount of leak is confirmed by creating a soap film inside the glass tube, etc., guiding the leaked air into the glass tube, and measuring the distance the soap film has moved by the air. In advance, the amount (volume) of leaked air with respect to the movement distance of the soap film is obtained. The case where the leak amount was 0.1 cm ³ / min or less was regarded as acceptable.

As a result of evaluating the sealing state of the plate-like sensor element of Example 1, it is 0.08 cm ³ / min, which indicates that the plate-like sensor element is well sealed.

Plate-like sensor element of the present invention is contained in incineration flue gas or the like generated during incineration of automobile exhaust gas or waste, in order to detect the dust and other particulate matter, NO X in the flue _gas, CO and HC In addition, it can be used to detect substances such as O _{2 in} various other gases.

It is a perspective view which shows one Embodiment of the plate-shaped sensor element of this invention. It is a perspective view which shows other embodiment of the plate-shaped sensor element of this invention. It is a perspective view which shows other embodiment of the plate-shaped sensor element of this invention. It is a perspective view which shows the green sheet laminated body formed in the manufacture process of the plate-shaped sensor element of this embodiment. The center axis of the plate sensor element showing the state where the plate sensor element of the present embodiment is inserted and fixed in the housing, and the housing in which the plate sensor element is fixed is fixed to the pipe while being inserted into the hole of the pipe. It is sectional drawing cut | disconnected by the plane containing a fluid distribution direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101,201: Plate-shaped sensor element, 2: Ceramic base material, 3,103,203: Sensor element main body, 4,104,204: Sealing part, 4a: Sealing surface, 4b: Sealing part back surface, 5: Sensor part, 6, 206: One end part, 7a: One end face, 7b: End face located on the opposite side, 8: The other end part, 11: Sealing ring, 12: Sealing ring, 13: Piping, 13a: Hole in piping, 14: Fixing member, 15: Claw part for caulking, 16: Sealing part contact surface, 17: Through hole, 18: Inner wall surface, 20: Housing, 20a: Housing body, 20b: Screw part, 20c: Hexagon part, 19: Outer wall surface, 21: Green sheet laminate, 22: Ceramic green sheet, 23: Part corresponding to sensor element body, 24: Part corresponding to sealing part, W: Sealing Width of surface, X: Length, L: From sealing part to one end Length, f: fluid circulation direction, theta: angle.

Claims (5)

A plate-shaped sensor element body having a plate-shaped ceramic substrate;
A ring-shaped sealing portion disposed so as to surround a part of the sensor element body,
The sensor element body has a sensor portion between a position where the sealing portion is disposed and one end portion,
A plate-like sensor element in which the material of the sealing part is ceramic and the sensor element body and the sealing part are integrally formed. The material of the ceramic substrate is at least one selected from cordierite, alumina, zirconia, titania, silicon nitride, silicon carbide and ferrite,
The plate-shaped sensor element according to claim 1, wherein a material of the sealing portion is at least one selected from cordierite, alumina, zirconia, titania, silicon nitride, spinel, silica, and mullite.   The plate-like sensor element according to claim 1 or 2, wherein a green sheet laminate having a plurality of tape-shaped ceramic green sheets is formed by firing. The sealing portion has a sealing surface facing the sensor unit side and in contact with the outer peripheral surface of the sensor element body,
The plate-shaped sensor element according to any one of claims 1 to 3, wherein an angle between the sealing surface and an outer peripheral surface of the sensor element body in contact with the sealing surface is 90 to 135 °.   The plate-like sensor element according to claim 4 whose width of said sealing face is 1-10 mm over the perimeter.

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