WO2018147287A1 - Heating device for manufacturing gas sensor - Google Patents

Heating device for manufacturing gas sensor Download PDF

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Publication number
WO2018147287A1
WO2018147287A1 PCT/JP2018/004077 JP2018004077W WO2018147287A1 WO 2018147287 A1 WO2018147287 A1 WO 2018147287A1 JP 2018004077 W JP2018004077 W JP 2018004077W WO 2018147287 A1 WO2018147287 A1 WO 2018147287A1
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Prior art keywords
induction heating
heating coil
sensor element
electrode
manufacturing
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PCT/JP2018/004077
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French (fr)
Japanese (ja)
Inventor
翔太郎 森
籔谷　正文
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株式会社デンソー
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Publication of WO2018147287A1 publication Critical patent/WO2018147287A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/409—Oxygen concentration cells

Definitions

  • the present disclosure relates to a manufacturing heating apparatus that heats an intermediate body of a sensor element from the outside.
  • the gas sensor is arranged in the piping of the exhaust system of the internal combustion engine, and performs gas detection by utilizing a change in oxygen concentration in the exhaust gas flowing through the piping.
  • the gas sensor includes an application for detecting the oxygen concentration of exhaust gas exhausted from the internal combustion engine, an application for detecting the air-fuel ratio of the internal combustion engine obtained from the exhaust gas, and the air-fuel ratio of the internal combustion engine obtained from the exhaust gas relative to the theoretical air-fuel ratio.
  • the gas sensor has a sensor element made of a solid electrolyte body with electrodes provided on both surfaces.
  • the sensor element is often provided with a heater for heating the sensor element to the sensor activation temperature.
  • the heater may be disposed inside the bottomed cylindrical sensor element or may be stacked on a plate-like sensor element.
  • a sensor element in which no heater is disposed may be used.
  • the intermediate body of the sensor element before manufacture completion is arrange
  • a heater that generates heat by Joule heat during energization is disposed inside or around the intermediate body of the sensor element, and the intermediate body may be heated by heat conduction from the heater or the like by generating heat.
  • the coil described in the gas sensor manufacturing method of Patent Document 1 is used to heat the metal shell that holds the sensor element when the gas sensor is manufactured. .
  • This coil removes the oil adhering to the metallic shell by arranging and energizing around the assembly in which the sensor element and the metallic shell are assembled.
  • an induction coil described in the gas sensor of Patent Document 2 is used to heat the sensor element when the gas sensor is used.
  • This induction coil is disposed on the inner peripheral surface of the cover that covers the sensor element, and heats the sensor element to the sensor activation temperature by causing the electrodes provided on the solid electrolyte body to generate heat when energized. Is.
  • the coil described in Patent Document 1 heats the metal shell and is not used to heat the intermediate of the sensor element.
  • the induction coil described in Patent Document 2 heats the sensor element when the gas sensor is used, and is not used for heating the intermediate body of the sensor element. Therefore, when heating the intermediate body of the sensor element, in order to heat the electrode or the entire porous ceramic layer as uniformly as possible in a short time, further ingenuity is required.
  • the present disclosure is intended to provide a heating device for manufacturing a gas sensor capable of obtaining a sensor element having necessary performance with high accuracy and in a short time.
  • One aspect of the present disclosure is used in a gas sensor (4) that performs gas detection in exhaust gas (G) of an internal combustion engine, and includes a solid electrolyte body (51) provided with an outer electrode (52A) and an inner electrode (52B).
  • a heating apparatus (1) for manufacturing which is controlled by an energization control unit (2) different from the control apparatus (40) of the gas sensor and heats the intermediate body (50) of the sensor element, The energization control unit;
  • An induction heating coil (3) arranged in a spiral around the intermediate body and generating heat to the outer electrode and the inner electrode in the intermediate body by electromagnetic induction generated by energization and interruption of energization by the energization control unit;
  • a heating device for manufacturing a gas sensor used in the manufacture of the element (5).
  • the heating device for manufacturing the gas sensor is used for manufacturing a sensor element by heating an intermediate body of the sensor element.
  • the manufacturing heating apparatus includes an energization control unit and an induction heating coil arranged in a spiral around the intermediate body.
  • an eddy current is generated in the electrode in the intermediate body by electromagnetic induction, and the electrode self-heats due to this eddy current.
  • the whole electrode is heated as uniformly as possible in a short time, and accordingly, the periphery of the electrode is also heated as uniformly as possible in a short time.
  • the electrode When the electrode is sintered, when the electrode is heat-treated, when the porous ceramic layer covering the surface of the electrode is dried or sintered, the entire intermediate electrode is heated as uniformly as possible in a short time. Therefore, a sensor element having necessary performance can be obtained with high accuracy. Therefore, according to the heating device for manufacturing the gas sensor, a sensor element having necessary performance can be obtained accurately and in a short time.
  • gas detection indicates that the oxygen concentration of the exhaust gas exhausted from the internal combustion engine is detected, the air-fuel ratio of the internal combustion engine obtained from the exhaust gas is detected, and the air condition of the internal combustion engine obtained from the exhaust gas is detected. This includes detecting whether the fuel ratio is on the fuel rich side or the fuel lean side with respect to the stoichiometric air-fuel ratio, detecting the concentration of a specific gas component such as NOx, and the like.
  • the “heating device for manufacturing” is different from the heater as the heating device built in the gas sensor.
  • “Gas sensor control device” indicates a control device used when gas detection is performed by a gas sensor
  • “energization control unit” indicates a control device used when a sensor element is manufactured.
  • the “electrode in the intermediate” includes both an electrode before sintering and an electrode after sintering.
  • the following manufacturing method of a gas sensor is realizable by using the heating apparatus for manufacturing a gas sensor.
  • An electrode material arranging step of arranging an electrode material for forming an electrode on both surfaces of the solid electrolyte body Using an induction heating coil arranged in a spiral around the intermediate body of the sensor element and an energization control unit for energizing the induction heating coil, the energization and energization of the induction heating coil from the energization control unit is performed.
  • There is a gas sensor manufacturing method including an electrode forming step of forming the electrode from the electrode material by causing the electrode material to generate heat by electromagnetic induction generated by being interrupted.
  • electrodes are provided on both surfaces of the solid electrolyte body, and the surface of one of the outer electrodes is covered with a porous ceramic layer, so that gas detection in exhaust gas from an internal combustion engine is performed.
  • a ceramic layer forming step of forming the porous ceramic layer from the ceramic material by heat conduction from the outer electrode to the ceramic material. is there.
  • FIG. 1 is a cross-sectional view showing a gas sensor according to a first embodiment.
  • FIG. 3 is a cross-sectional view showing the sensor element according to the first embodiment. 3 is a flowchart showing a method for manufacturing a sensor element according to the first embodiment.
  • FIG. 5 is a flowchart showing another sensor element manufacturing method according to the first embodiment.
  • Sectional drawing which expands and shows the periphery of the intermediate body and induction heating coil of a sensor element concerning Embodiment 1.
  • FIG. The graph which shows simply the change of the temperature of an intermediate body when heating an intermediate body to target temperature with the heating apparatus of the implementation goods, the comparative goods 1, and the comparative goods 2 concerning Embodiment 1.
  • FIG. Explanatory drawing which shows the heating apparatus for manufacture concerning Embodiment 2.
  • FIG. which shows the difference of the electrical resistance between a pair of electrodes before and behind sintering concerning Embodiment 2.
  • FIG. The graph which shows the difference of the electrical resistance between a pair of electrodes according to Embodiment 2 according to the presence or absence of a disconnection.
  • FIG. 1 Explanatory drawing which shows the heating apparatus for manufacture concerning Embodiment 3.
  • the heating device 1 for manufacturing the gas sensor 4 of this embodiment is used when manufacturing a sensor element 5 used for the gas sensor 4 as shown in FIG.
  • the gas sensor 4 performs gas detection in the exhaust gas G of the internal combustion engine, and the sensor element 5 is provided with electrodes 52A and 52B on both surfaces of the solid electrolyte body 51, respectively.
  • the manufacturing heating apparatus 1 heats the intermediate body 50 of the sensor element 5 before becoming a complete body when the sensor element 5 is manufactured.
  • the manufacturing heating device 1 is arranged in a spiral around the energization control unit 2 and the intermediate body 50 provided separately from the control device 40 of the gas sensor 4, and receives energization and interruption of energization by the energization control unit 2. And an induction heating coil 3 that generates heat in the electrodes 52A and 52B in the intermediate 50 by electromagnetic induction that occurs.
  • the manufacturing heating apparatus 1 of this embodiment is used when manufacturing the sensor element 5 and is not used for heating the sensor element 5 when the gas sensor 4 is used.
  • the manufacturing heating apparatus 1 operates independently of the gas sensor 4 when the sensor element 5 is manufactured.
  • the gas sensor 4 of this embodiment is a heaterless type that does not have a heater for heating the sensor element 5, and the sensor element 5 cannot be heated by the heater.
  • the intermediate body 50 of the sensor element 5 is in a state before the manufacture of the sensor element 5 is completed.
  • the intermediate body 50 of the sensor element 5 heated by the manufacturing heating apparatus 1 can be a single body of the solid electrolyte body 51 provided with the electrodes 52A and 52B. Further, as shown in FIG. 13, the intermediate body 50 is a solid electrolyte body 51 provided with electrodes 52 ⁇ / b> A and 52 ⁇ / b> B, and may be in a state assembled to each component of the gas sensor 4. However, each part of the gas sensor 4 to which the intermediate body 50 is assembled is assumed to be in a state where an element cover 44 described later is removed.
  • the gas sensor 4 of this embodiment is a heaterless type that does not incorporate a heater, and is mounted on a two-wheeled vehicle.
  • the gas sensor 4 is disposed in a pipe of an exhaust system of an internal combustion engine in a two-wheeled vehicle, and detects gas in the exhaust gas G flowing through the pipe.
  • the gas sensor 4 of this embodiment detects oxygen in the exhaust gas G, and detects whether the air-fuel ratio of the internal combustion engine obtained from the exhaust gas G is on the fuel rich side or the fuel lean side with respect to the theoretical air fuel ratio. It is.
  • the gas sensor 4 may be one that detects the air-fuel ratio of the internal combustion engine obtained from the exhaust gas G, or one that detects the concentration of a specific gas component such as NOx.
  • the solid electrolyte body 51 of the sensor element 5 is formed in a bottomed cylindrical shape, and includes a cylindrical portion 511 and a hemispherical bottom portion 512 that closes the distal end side of the cylindrical portion 511.
  • the electrodes 52A and 52B include an outer electrode 52A provided on the outer peripheral surface of the solid electrolyte body 51 and in contact with the exhaust gas G, and an inner electrode 52B provided on the inner peripheral surface of the solid electrolyte body 51 and in contact with the atmosphere A. is there.
  • the outer electrode 52A is provided on the outer peripheral surface of the cylindrical portion 511 of the solid electrolyte body 51 at the bottom position located in the vicinity of the bottom portion 512.
  • the inner electrode 52 ⁇ / b> B is provided on the entire inner peripheral surface of the cylindrical portion 511 of the solid electrolyte body 51.
  • the detection portion 501 of the sensor element 5 is formed as a portion where the outer electrode 52A and the inner electrode 52B face each other with the solid electrolyte body 51 interposed therebetween.
  • an electrode lead portion 521 connected to the outer electrode 52A in a state parallel to the axial direction L of the cylindrical portion 511 is formed on the outer peripheral surface of the cylindrical portion 511 of the solid electrolyte body 51.
  • the electrode lead portion 521 is not included in the outer electrode 52A.
  • the solid electrolyte body 51 is made of a zirconia material having a property of transmitting oxide ions (O 2 ⁇ ).
  • a zirconia material can be comprised with the various material which has a zirconia as a main component.
  • As the zirconia material stabilized zirconia or partially stabilized zirconia in which a part of zirconia is substituted with a rare earth metal element or an alkaline earth metal element can be used.
  • the outer electrode 52 ⁇ / b> A and the inner electrode 52 ⁇ / b> B contain platinum as an oxygen active catalyst that reacts with oxygen and a zirconia material that is a co-material of the solid electrolyte body 51.
  • a porous ceramic layer 53 is provided on the surface of the outer electrode 52A so as to cover the outer electrode 52A and prevent the permeation of water and poisonous substances to protect the outer electrode 52A.
  • the porous ceramic layer 53 is provided on the bottom side position of the cylindrical portion 511 of the solid electrolyte body 51 and the entire circumference of the bottom portion 512 including the outer electrode 52A.
  • the porous ceramic layer 53 is formed of a porous body of a ceramic material such as alumina.
  • the gas sensor 4 includes a housing 41 that holds the sensor element 5, connection terminals 42 and lead wires 43 that are electrically connected to the electrodes 52 ⁇ / b> A and 52 ⁇ / b> B of the sensor element 5.
  • An element cover 44 covering the detection portion 501 of the sensor element 5, a connection terminal 42, a terminal cover 45 covering a part of the lead wire 43, and the like.
  • the connection terminal 42 includes one that contacts the electrode lead portion 521 of the outer electrode 52A from the outer peripheral side and one that contacts the inner electrode 52B from the inner peripheral side.
  • the element cover 44 is provided with a through hole 441 through which the exhaust gas G passes.
  • the exhaust gas G flowing in the piping of the exhaust system flows into the element cover 44 through the through hole 441 and is guided to the porous ceramic layer 53 and the outer electrode 52A in the detection portion 501 of the sensor element 5.
  • the terminal cover 45 is provided with a through hole 451 through which the atmosphere A passes, and a sheet 452 for preventing water from entering the terminal cover 45 is disposed facing the through hole 451. ing.
  • the atmosphere A existing outside the piping of the exhaust system flows into the terminal cover 45 through the through hole 451 and is guided to the inner electrode 52 ⁇ / b> B in the detection unit 501 of the sensor element 5.
  • the spiral portion 31 of the induction heating coil 3 is formed in a circular shape in accordance with the circular sectional shape of the bottomed cylindrical solid electrolyte body 51.
  • the induction heating coil 3 is disposed to face the entire circumference of the outer electrode 52 ⁇ / b> A provided on the entire circumference of the cylindrical portion 511 of the solid electrolyte body 51.
  • the induction heating coil 3 is configured to heat the entire outer electrode 52A and the portion of the inner electrode 52B that faces the outer electrode 52A via the solid electrolyte body 51.
  • the conductor 301 constituting the induction heating coil 3 is formed in a hollow shape having a refrigerant flow path 302 through which the refrigerant C passes.
  • the induction heating coil 3 When the induction heating coil 3 is energized, the induction heating coil 3 generates heat due to Joule heat. Therefore, by forming the induction heating coil 3 using the conductor 301 having the refrigerant flow path 302, the induction heating coil 3 is cooled by the refrigerant C flowing through the refrigerant flow path 302, and the induction heating coil 3 is prevented from fusing. can do. Thus, the induction heating coil 3 can cause the electrodes 52A and 52B to generate heat until the electrodes 52A and 52B in the intermediate 50 reach a high temperature of 400 to 1000 ° C.
  • the induction heating coil 3 is formed by spirally winding a conductor 301 having an annular cross section.
  • the length of the spiral portion 31 in the induction heating coil 3 in the axial direction L is longer than the length of the outer electrode 52A in the axial direction L.
  • the entire outer electrode 52A can be effectively heated by the induction heating coil 3.
  • the entire axial direction L of the outer electrode 52 ⁇ / b> A is disposed at the center of the induction heating coil 3.
  • the axial direction L of the spiral portion 31 refers to the direction in which the central axis passing through the circle center of the spiral portion 31 extends.
  • the outer diameter of the conductor 301 constituting the induction heating coil 3 is in the range of ⁇ 1.5 to 3 mm, and the inner diameter of the refrigerant flow path 302 is smaller than the outer diameter of the induction heating coil 3. , In the range of ⁇ 1 to 2.5 mm.
  • the cross-sectional area of the refrigerant flow path 302 becomes small and the refrigerant flow path 302 may be formed. It becomes difficult.
  • the outer diameter of the conductor 301 exceeds ⁇ 3 mm, or when the inner diameter of the refrigerant flow path 302 exceeds ⁇ 2.5 mm, the conductor 301 and the refrigerant flow path 302 become relatively large with respect to the sensor element 5, and the outside It becomes impossible to increase the number of turns of the conductor 301 opposed to the electrode 52A.
  • the induction heating coil 3 is formed by arranging the conductor 301 in a state of one layer winding in the radial direction around the central axis, and winding the conductor 301 three or more times in a spiral shape.
  • the number of turns of the conductor 301 in the induction heating coil 3 can be, for example, 10 or less.
  • a gap is formed between the conductors 301 constituting the induction heating coil 3 to ensure sufficient insulation between the conductors 301.
  • both end portions 32 of the induction heating coil 3 are supported by the heating head 21.
  • the heating head 21 is configured to be positioned with respect to the jig 11 that holds the intermediate body 50 of the sensor element 5.
  • the intermediate body 50 of the sensor element 5 and the induction heating coil 3 are positioned so that the central axis of the intermediate body 50 coincides with the central axis of the induction heating coil 3. .
  • the distance between the outermost surface of the intermediate body 50 and the inner peripheral side position of the induction heating coil 3 is 2 mm or less.
  • the outermost surface of the intermediate body 50 can be the surface of the outer electrode 52A, and the porous ceramic layer 53 is formed.
  • the surface of the porous ceramic layer 53 can be used.
  • the energization control unit 2 of this embodiment includes a cooling chiller 22 that circulates the refrigerant C through the refrigerant flow path 302 of the induction heating coil 3 and a thermometer 24 that measures the temperature of the bottom 512 of the intermediate body 50. And a controller 23 that applies an alternating voltage (or alternating current) to the induction heating coil 3, and a power source (not shown) that supplies power to the cooling chiller 22 and the controller 23.
  • the refrigerant C is supplied from the cooling chiller 22 to the induction heating coil 3 via the heating head 21, and is collected from the induction heating coil 3 to the cooling chiller 22 via the heating head 21.
  • the AC voltage generated by the controller 23 has a voltage waveform such as a sine wave or a pulse wave.
  • the cooling chiller 22 has a function of cooling the refrigerant C circulated through the refrigerant flow path 302 of the induction heating coil 3.
  • the thermometer 24 is a radiation thermometer that measures heat radiation (heat radiation) due to movement of electromagnetic waves from the intermediate body 50 of the sensor element 5 in a non-contact manner.
  • heat radiation heat radiation
  • the thermometer 24 is disposed so as to face the tip of the bottom 512 of the intermediate body 50, and measures the temperature due to heat radiation from the tip of the bottom 512 in a non-contact manner.
  • the controller 23 is configured using a computer.
  • the controller 23 has a function of adjusting the amplitude and frequency of the AC voltage applied to the induction heating coil 3, a function of setting a target temperature and a voltage application time for heating the intermediate body 50 to be heated by the induction heating coil 3, and a heating target A function of monitoring the temperature of the intermediate body 50, a function of performing feedback control so that the temperature of the intermediate body 50 becomes the target temperature, and the like.
  • setting of the target temperature, setting of the amplitude, frequency and application time of the AC voltage are possible.
  • the cooling chiller 22, the heating head 21, and the thermometer 24 are connected to a controller 23.
  • the temperature of the bottom 512 of the intermediate body 50 measured by the thermometer 24 is transmitted to the controller 23.
  • Both end portions 32 of the induction heating coil 3 are connected to the controller 23 via the heating head 21. Then, an AC voltage is applied to the induction heating coil 3 by the controller 23.
  • the controller 23 is configured to adjust the amplitude (magnitude) and frequency of the AC voltage applied to the induction heating coil 3 so that the temperature measured by the thermometer 24 becomes the target temperature.
  • the temperature of the electrodes 52A and 52B in the intermediate body 50 can be controlled to be an appropriate temperature. Therefore, the sensor element 5 having performance necessary for performing gas detection can be obtained with high accuracy.
  • the target temperature is determined when the electrodes 52A and 52B in the intermediate body 50 of the sensor element 5 are sintered, or when the electrodes 52A and 52B in the intermediate body 50 of the sensor element 5 are heat-treated.
  • the temperature is set to an appropriate temperature in accordance with each production scene such as when the porous ceramic layer 53 disposed in the substrate is dried or sintered.
  • thermometer 24 may not be used. . In this case, the temperature of the intermediate body 50 is not measured, and the controller 23 can heat the intermediate body 50 to a target temperature by feedforward control.
  • Electrodes 52A and 52B First, the case where the electrodes 52A and 52B are formed on the surface of the solid electrolyte body 51 will be described.
  • an electrode material arranging step S1 and an electrode forming step S2 are performed to form the electrodes 52A and 52B.
  • electrode materials for forming the electrodes 52A and 52B are arranged on both surfaces of the solid electrolyte body 51.
  • the electrode material includes precious metal particles such as platinum, solid electrolyte particles, a solvent, and the like that constitute the electrodes 52A and 52B.
  • the electrode material may be a plating material for performing a precious metal plating process.
  • the intermediate body 50 of the sensor element 5 in which the electrode material is disposed on the solid electrolyte body 51 is disposed inside the spiral portion 31 of the induction heating coil 3.
  • the central axis of the intermediate body 50 is made to coincide with the central axis of the spiral portion 31.
  • the thermometer 24 is disposed at a position facing the tip of the bottom 512 of the intermediate body 50.
  • the target temperature for heating the electrode material, the amplitude, frequency, application time, and the like of the AC voltage applied to the induction heating coil 3 are set.
  • the controller 23 applies an AC voltage to the induction heating coil 3 and operates the cooling chiller 22 to circulate the refrigerant C through the refrigerant flow path 302 of the induction heating coil 3.
  • an alternating voltage is applied to the spiral portion 31 of the induction heating coil 3
  • a magnetic field M penetrating the inner peripheral side of the induction heating coil 3 is generated in response to energization and interruption of energization.
  • an eddy current for canceling the magnetic field M is generated, and the electrode material self-heats due to the generation of the eddy current.
  • the entire electrode material of the outer electrode 52A and the entire electrode material in the portion of the inner electrode 52B facing the outer electrode 52A are heated as uniformly as possible.
  • the temperature of the tip of the bottom 512 in the intermediate body 50 is measured by the thermometer 24, and the controller 23 applies alternating current to the induction heating coil 3 so that the temperature measured by the thermometer 24 becomes the target temperature. Adjust the voltage amplitude and frequency. The adjustment by the controller 23 is performed for the set application time. Note that the target temperature can be changed as appropriate while the electrode material generates heat as the heating of the intermediate 50.
  • the electrode material arranged on the surface of the solid electrolyte body 51 is sintered, and the electrodes 52A and 52B are formed on the surface of the solid electrolyte body 51.
  • the heating of the intermediate body 50 by the induction heating coil 3 can also be performed to heat-treat the electrodes 52A and 52B provided on the surface of the solid electrolyte body 51. Also in this case, the electrodes 52A and 52B are self-heated by the induction heating coil 3 as in the case where the electrodes 52A and 52B are sintered.
  • the ceramic material arranging step S3 and the ceramic layer forming step S4 are performed to form the porous ceramic layer 53.
  • a ceramic material for forming the porous ceramic layer 53 is arranged on the surface of the intermediate body 50 of the sensor element 5 including the surface of the outer electrode 52A.
  • the ceramic material is in the form of a slurry containing ceramic particles such as alumina, a volatilizing agent for forming a large number of pores, a solvent, and the like.
  • the intermediate body 50 of the sensor element 5 in which the ceramic material is disposed on the solid electrolyte body 51 and the electrodes 52A and 52B is replaced with the spiral shape of the induction heating coil 3.
  • the induction heating coil 3 cools the induction heating coil 3 with the refrigerant C of the cooling chiller 22, and the induction heating coil 3 causes the electrodes 52A and 52B to generate heat.
  • the controller 23 adjusts the amplitude and frequency of the AC voltage applied to the induction heating coil 3 so that the temperature of the intermediate 50 measured by the thermometer 24 becomes the target temperature.
  • the ceramic material is heated by heat conduction from the outer electrode 52A and the inner electrode 52B. Then, the ceramic material is dried and solidified to form the porous ceramic layer 53. At this time, the inner part in contact with the outer electrode 52A is first heated and dried and solidified, and the ceramic material is sequentially heated from the inner part to the outer part by heat conduction to be dried and solidified.
  • the internal pressure of the ceramic material increases due to evaporation of a solvent such as water contained in the ceramic material.
  • the outer portion of the ceramic material when the outer portion of the ceramic material is dried and solidified, the outer portion of the ceramic material is not dried and solidified, so that the internal pressure generated in the inner portion of the ceramic material can be released to the outer portion.
  • the internal pressure hardly remains in the inner portion of the ceramic material, and cracks due to bumping can hardly occur in the porous ceramic layer 53 formed from the ceramic material.
  • the ceramic material is heated by using a conventional heating device that performs heating by heat radiation, heat conduction, convection, etc. instead of the manufacturing heating device 1, the ceramic material is dried and solidified first from the outer portion. Then, it is heated by heat conduction sequentially from the outer part to the inner part and dried and solidified.
  • the outer part of the ceramic material is dried and solidified while the solvent remains in the inner part of the ceramic material, and when the refrigerant C of the inner part evaporates, the internal pressure of the inner part increases. Therefore, the porous ceramic layer 53 formed from the ceramic material may be cracked due to bumping.
  • FIG. 8 shows that the intermediate body 50 is manufactured by a manufacturing heating device 1 using induction heating (practical product), a heating device using Joule heat (comparative product 1), and a heating device using a heating furnace (comparative product 2).
  • the change of the temperature of the intermediate body 50 when heating to target temperature is shown simply.
  • the temperature of the intermediate body 50 is the temperature of the tip of the bottom 512 of the solid electrolyte body 51 constituting the intermediate body 50.
  • the comparative product 1 a case where a part of the heating device is brought into contact with the intermediate body 50 is shown.
  • the time for heating the intermediate 50 to the target temperature can be shortened as compared with the comparative product 1 using Joule heat.
  • the entire outer electrode 52A and the entire portion of the inner electrode 52B facing the outer electrode 52A self-heats. Therefore, it is considered that the amount of heat transfer from each electrode 52A, 52B to the bottom 512 of the solid electrolyte body 51 is increased, and the heating time is shortened.
  • the entire outer electrode 52A and the entire portion of the inner electrode 52B facing the outer electrode 52A can be caused to generate heat substantially uniformly.
  • the intermediate 50 when the intermediate 50 and the heating device are in contact, the intermediate 50 is heated by heat conduction from the heating device. Since this heat conduction is locally performed from a part of the electrodes 52A, 52B or the solid electrolyte body 51, the heating time becomes long. In addition, it is difficult to uniformly heat the entire outer electrode 52A and the entire portion of the inner electrode 52B facing the outer electrode 52A.
  • the intermediate 50 when the intermediate 50 is not in contact with the heating device, the intermediate 50 is heated by heat radiation from the heating device. In this case, the heat is carried by electromagnetic waves due to thermal radiation, so that the heating time becomes long. Moreover, also in the comparative product 2, since the intermediate body 50 is heated by thermal radiation or convection, the heating time is remarkably increased.
  • the entire outer electrode 52A in the intermediate body 50 and the entire portion facing the outer electrode 52A in the inner electrode 52B are substantially uniformly and in a short time. Can be heated. Thereby, the outer electrode 52A or the porous ceramic layer 53 in a target state can be formed, and the sensor element 5 having necessary performance can be obtained with high accuracy. Therefore, according to the manufacturing heating apparatus 1 of this embodiment, the sensor element 5 having necessary performance can be obtained with high accuracy and in a short time.
  • the configuration of the energization control unit 2 is different from the configuration of the energization control unit 2 shown in the first embodiment.
  • the energization control unit 2 of this embodiment includes a resistance detection unit that detects an electrical resistance between the outer electrode 52 ⁇ / b> A and the inner electrode 52 ⁇ / b> B through the solid electrolyte body 51 in the intermediate body 50 of the sensor element 5. 25 and a controller 23 for applying an AC voltage to the induction heating coil 3.
  • the controller 23 is configured to start energizing the induction heating coil 3, detect that the electrical resistance by the resistance detection unit 25 has become a predetermined threshold value or less, and end energization to the induction heating coil 3. .
  • the resistance detector 25 is connected to the electrode lead 521 connected to the outer electrode 52A of the bottomed cylindrical solid electrolyte body 51 and the end of the inner electrode 52B on the opening side opposite to the bottom.
  • the induction heating coil 3 is supported by the heating head 21, and the energization control unit 2 has a cooling chiller 22 and a power source.
  • the controller 23 the amplitude, frequency, application time, and the like of the AC voltage applied to the induction heating coil 3 are set.
  • the electrical resistance between the outer electrode 52A and the inner electrode 52B via the solid electrolyte body 51 includes the inner resistance of the outer electrode 52A and the inner electrode 52B, the inner resistance of the solid electrolyte body 51, the outer electrode 52A and the inner electrode 52B, and the solid Interface resistance between the electrolyte body 51 and the like are included. As shown in FIGS. 10 and 11, this electrical resistance is related to the temperature of the solid electrolyte body 51 and becomes lower as the temperature of the solid electrolyte body 51 is higher. In each of the figures, a change in electrical resistance when the solid electrolyte body 51 is heated from room temperature (20 ° C.) to 400 ° C. and then maintained at 400 ° C. is shown.
  • the induction heating coil 3 is energized until the set application time elapses. And when this application time passes, in order to confirm whether sintering of electrode 52A, 52B was performed normally, the electrical resistance between a pair of electrodes 52A, 52B is measured by the resistance detection part 25.
  • the electrical resistance is equal to or less than the threshold value indicating the completion of sintering
  • the energization to the induction heating coil 3 is terminated on the assumption that the sintering has been normally performed.
  • the electrical resistance is not less than or equal to the threshold value indicating the completion of sintering
  • the energization to the induction heating coil 3 is continued assuming that the sintering has not been completed yet.
  • the electrical resistance in the case where there is a partial disconnection or a complete disconnection between the pair of electrodes 52A and 52B is the disconnection. It becomes higher than the electric resistance when it does not occur. Therefore, if the electrical resistance does not fall below the threshold value even after a preparatory time longer than the application time, it can be estimated that a disconnection has occurred between the pair of electrodes 52A and 52B. The disconnection occurs due to peeling of the electrodes 52A and 52B, fading due to the thinning of the electrodes 52A and 52B, chipping or cracking of the solid electrolyte body 51, and the like.
  • the other components of the manufacturing heating apparatus 1 and the components indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment. And the effect similar to Embodiment 1 can be acquired.
  • the heating device 1 for manufacturing the gas sensor 4 performs an inspection of whether the sensor element 5 or the intermediate body 50 after heating is functioning normally in addition to the function of energizing the induction heating coil 3. It has a function.
  • the energization control unit 2 of the present embodiment is detected by a current detection unit 26 that detects a current flowing between the outer electrode 52A and the inner electrode 52B via the solid electrolyte body 51, and a current detection unit 26.
  • a determination unit 27 that determines whether or not the current to be output is equal to or greater than a predetermined threshold value.
  • the current detection unit 26 is in contact with the oxygen concentration of the fluid R1 to be brought into contact with the outer electrode 52A of the solid electrolyte body 51 of the sensor element 5 or the intermediate body 50 and the inner electrode 52B of the solid electrolyte body 51 of the sensor element 5 or the intermediate body 50.
  • the current flowing between the outer electrode 52A and the inner electrode 52B is detected when the oxygen concentration of the fluid R2 to be made is different.
  • the threshold value used in the determination unit 27 is determined by adding a margin to the current flowing between the outer electrode 52A and the inner electrode 52B according to the difference between the oxygen concentration in the outer electrode 52A and the oxygen concentration in the inner electrode 52B.
  • the determination unit 27 can be configured in the controller 23, or can be configured by a control device different from the controller 23.
  • the current detection unit 26 is connected to the electrode lead portion 521 connected to the outer electrode 52A of the bottomed cylindrical solid electrolyte body 51 and the end portion of the inner electrode 52B on the opening side opposite to the bottom side.
  • the induction heating coil 3 is supported by the heating head 21, and the energization control unit 2 has a cooling chiller 22 and a power source.
  • the controller 23 the amplitude, frequency, application time, and the like of the AC voltage applied to the induction heating coil 3 are set.
  • FIG. 12 the details of the manufacturing heating apparatus 1 are omitted.
  • the oxygen concentration of the fluid R1 brought into contact with the outer electrode 52A is made different from the oxygen concentration of the fluid R2 brought into contact with the inner electrode 52B.
  • the inner electrode 52B is brought into contact with the atmosphere A as the fluid R2, and the outer electrode 52A is more oxygenated than the atmosphere A.
  • a gas as the fluid R1 having a low concentration is brought into contact.
  • the electrodes 52A and 52B and the solid electrolyte body 51 may be heated by energizing the induction heating coil 3 so that the electrodes 52A and 52B and the solid electrolyte body 51 have a catalytic activity.
  • oxide ions (O 2 ⁇ ) permeate the solid electrolyte body 51 and A current flows between the electrode 52B. Therefore, the current flowing between the outer electrode 52A and the inner electrode 52B is measured by the current detection unit 26.
  • the determination unit 27 determines that the sensor element 5 or the intermediate body 50 functions normally in order to perform gas detection. Or it determines with the intermediate body 50 being non-defective.
  • the determination unit 27 determines that the sensor element 5 or the intermediate body 50 does not function normally in order to perform gas detection. Or it determines with the intermediate body 50 being inferior goods. In this embodiment, it can be inspected whether the sensor element 5 or the intermediate body 50 functions normally for gas detection, and the manufacturing accuracy of the sensor element 5 can be increased.
  • the other components of the manufacturing heating apparatus 1 and the components indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment. And the effect similar to Embodiment 1 can be acquired.
  • the manufacturing heating apparatus 1 is used when inspecting whether the gas detection by the sensor element 5 in a state assembled to the housing 41 or the like functions normally.
  • the element cover 44 (see FIG. 3) is removed from the gas sensor 4 to which the sensor element 5 of this embodiment is assembled. And the sensor element 5 in the gas sensor 4 from which the element cover 44 is removed is heated to a temperature at which the pair of electrodes 52A and 52B and the solid electrolyte body 51 have catalytic activity by the induction heating coil 3 of the manufacturing heating apparatus 1.
  • the oxygen concentration of the fluid brought into contact with the outer electrode 52A is made different from the oxygen concentration of the fluid brought into contact with the inner electrode 52B. Specifically, the atmosphere A is brought into contact with the inner electrode 52B, and a gas having a lower oxygen concentration than the atmosphere A is brought into contact with the outer electrode 52A.
  • the manufacturing heating apparatus 1 of the third embodiment including the energization control unit 2 having the current detection unit 26 and the determination unit 27 is used.
  • the details of the manufacturing heating apparatus 1 are omitted.
  • the determination unit 27 determines that the gas sensor 4 functions normally to perform gas detection, and determines that the gas sensor 4 is a non-defective product. To do.
  • the determination unit 27 determines that the gas sensor 4 is defective because the gas sensor 4 does not function normally for gas detection. judge.
  • the determination unit 27 can be configured in the controller 23, or can be configured by a control device different from the controller 23.
  • the gas sensor 4 when the gas sensor 4 does not include a heater that generates heat when energized, the sensor element 5 in the gas sensor 4 can be heated from the outside of the gas sensor 4 using the manufacturing heating device 1. Therefore, by using the manufacturing heating apparatus 1, it is possible to perform a function test in the heaterless gas sensor 4 that does not incorporate a heater.
  • the sensor element 5 in this embodiment is of a laminated type in which a pair of electrodes 52 ⁇ / b> A and 52 ⁇ / b> B are provided on a plate-shaped solid electrolyte body 51.
  • the pair of electrodes 52A and 52B is provided on one surface of the solid electrolyte body 51 and provided on the other surface of the solid electrolyte body 51 and the outer electrode 52A in contact with the exhaust gas G, and the atmosphere A is in contact therewith.
  • a porous ceramic layer 53 is formed as a diffusion resistance layer for adjusting the flow rate of the exhaust gas G reaching the outer electrode 52A.
  • the sensor element 5 is formed in an elongated rectangular parallelepiped shape having a rectangular cross-section with chamfered corners and fillet processing.
  • the pair of electrodes 52 ⁇ / b> A and 52 ⁇ / b> B is formed at the distal end portion of the elongated sensor element 5.
  • a duct 54 for taking in the atmosphere A into the inner electrode 52B is formed inside the sensor element 5.
  • the sensor element 5 of this embodiment does not include a heater.
  • the induction heating coil 3 of the present embodiment is formed by winding a conductor 301 in an oval shape (oval shape) and spirally in accordance with a rectangular cross section of the sensor element 5. Yes.
  • the induction heating coil 3 is formed such that the gap S between the long side portion of the elliptical conductor 301 and the surface of the sensor element 5 is 2 mm or less.
  • Other configurations of the manufacturing heating apparatus 1 of the present embodiment are the same as those shown in the first embodiment.
  • the multilayer sensor element 5 can be effectively heated, and the multilayer sensor element 5 having necessary performance can be obtained accurately and in a short time. it can.
  • the configuration of the manufacturing heating apparatus 1 is not limited to that shown in the first to fifth embodiments, and further different embodiments can be configured without departing from the gist of the present disclosure.
  • the present disclosure includes various modifications and modifications within the equivalent range.

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Abstract

A heating device (1) for manufacturing a gas sensor (4) heats an intermediate body (50) of a sensor element (5) prior to becoming a finished body, when the sensor element (5) is being manufactured. The heating device (1) for manufacture is provided with: an energization control unit (2) provided separately from a control device of the gas sensor (4); and an induction heating coil (3) which is arranged in a helical shape around the intermediate body (50), and which causes electrodes (52A, 52B) in the intermediate body (50) to generate heat by means of electromagnetic induction caused by the induction heating coil (3) being subjected to energization and interruption of energization by the energization control unit (2).

Description

ガスセンサの製造用加熱装置Heating device for gas sensor manufacturing 関連出願の相互参照Cross-reference of related applications
　本出願は、２０１７年２月９日に出願された日本の特許出願番号２０１７－０２２３１１号に基づくものであり、その記載内容を援用する。 This application is based on Japanese Patent Application No. 2017-022311 filed on Feb. 9, 2017, the contents of which are incorporated herein by reference.
　本開示は、センサ素子の中間体を外部から加熱する製造用加熱装置に関する。 The present disclosure relates to a manufacturing heating apparatus that heats an intermediate body of a sensor element from the outside.
　ガスセンサは、内燃機関の排気系統の配管内に配置され、配管内を流れる排ガス中の酸素濃度の変化等を利用して、ガス検出を行うものである。ガスセンサには、内燃機関から排気される排ガスの酸素濃度を検出する用途、排ガスから求められる内燃機関の空燃比を検出する用途、排ガスから求められる内燃機関の空燃比が、理論空燃比に対して燃料リッチ側にあるか燃料リーン側にあるかを検出する用途、ＮＯｘ等の特定ガス成分を検出する用途等がある。 The gas sensor is arranged in the piping of the exhaust system of the internal combustion engine, and performs gas detection by utilizing a change in oxygen concentration in the exhaust gas flowing through the piping. The gas sensor includes an application for detecting the oxygen concentration of exhaust gas exhausted from the internal combustion engine, an application for detecting the air-fuel ratio of the internal combustion engine obtained from the exhaust gas, and the air-fuel ratio of the internal combustion engine obtained from the exhaust gas relative to the theoretical air-fuel ratio. There are applications for detecting whether the fuel is on the fuel rich side or the fuel lean side, and for detecting a specific gas component such as NOx.
　ガスセンサは、電極が両表面に設けられた固体電解質体によるセンサ素子を有する。センサ素子には、センサ素子をセンサ活性温度に加熱するためのヒータが配置されることが多い。ヒータは、有底円筒状のセンサ素子の内側に配置される場合、板状のセンサ素子に積層される場合等がある。また、例えば、二輪自動車の内燃機関に採用されるガスセンサにおいては、ヒータが配置されないセンサ素子が用いられることがある。 The gas sensor has a sensor element made of a solid electrolyte body with electrodes provided on both surfaces. The sensor element is often provided with a heater for heating the sensor element to the sensor activation temperature. The heater may be disposed inside the bottomed cylindrical sensor element or may be stacked on a plate-like sensor element. For example, in a gas sensor employed in an internal combustion engine of a two-wheeled vehicle, a sensor element in which no heater is disposed may be used.
　センサ素子を製造する際には、電極を焼結させるための加熱、電極の熱処理のための加熱、電極の表面を覆う多孔質セラミック層を乾燥又は焼結させるための加熱等が行われる。そして、製造完了前のセンサ素子の中間体を加熱炉内に配置し、熱放射又は対流によって中間体を加熱している。また、センサ素子の中間体の内側又は周辺に、通電時のジュール熱によって発熱するヒータを配置し、このヒータを発熱させて、ヒータからの熱伝導等によって中間体を加熱することもある。 When the sensor element is manufactured, heating for sintering the electrode, heating for heat treatment of the electrode, heating for drying or sintering the porous ceramic layer covering the surface of the electrode, and the like are performed. And the intermediate body of the sensor element before manufacture completion is arrange | positioned in a heating furnace, and the intermediate body is heated by thermal radiation or a convection. In addition, a heater that generates heat by Joule heat during energization is disposed inside or around the intermediate body of the sensor element, and the intermediate body may be heated by heat conduction from the heater or the like by generating heat.
　センサ素子の中間体を加熱するものではないが、ガスセンサを製造する際に、センサ素子が保持される主体金具を加熱するものとしては、特許文献１のガスセンサの製造方法に記載されたコイルがある。このコイルは、センサ素子及び主体金具が組み付けられた組付体の周囲に配置して通電することにより、主体金具に付着する油分を除去するものである。 Although the intermediate body of the sensor element is not heated, the coil described in the gas sensor manufacturing method of Patent Document 1 is used to heat the metal shell that holds the sensor element when the gas sensor is manufactured. . This coil removes the oil adhering to the metallic shell by arranging and energizing around the assembly in which the sensor element and the metallic shell are assembled.
　また、ガスセンサの使用時にセンサ素子を加熱するものとしては、特許文献２のガスセンサに記載された誘導コイルがある。この誘導コイルは、センサ素子を覆うカバーの内周面に配置されており、通電を行ったときに固体電解質体に設けられた電極を発熱させて、センサ素子を迅速にセンサ活性温度に加熱するものである。 In addition, an induction coil described in the gas sensor of Patent Document 2 is used to heat the sensor element when the gas sensor is used. This induction coil is disposed on the inner peripheral surface of the cover that covers the sensor element, and heats the sensor element to the sensor activation temperature by causing the electrodes provided on the solid electrolyte body to generate heat when energized. Is.
特開２０１６－５３４９８号公報Japanese Unexamined Patent Publication No. 2016-53498 特開２００６－１０５７６８号公報JP 2006-105768 A
　センサ素子の中間体を加熱する際に、加熱炉を用いる場合には、熱放射又は対流によって加熱が行われる。そのため、中間体の温度が目標温度に加熱されるまでの加熱時間が長くなるといった課題がある。その結果、センサ素子の生産性を向上させることができない。 When a heating furnace is used when heating the sensor element intermediate, heating is performed by thermal radiation or convection. Therefore, there exists a subject that the heating time until the temperature of an intermediate body is heated to target temperature becomes long. As a result, the productivity of the sensor element cannot be improved.
　また、センサ素子の中間体を加熱する際に、通電によって発熱するヒータを使用する場合には、熱伝導、熱放射等によって加熱が行われる。そのため、電極の全体が均一に加熱されにくいといった課題がある。その結果、必要な性能を有するセンサ素子が得られないおそれがある。 Also, when a heater that generates heat when energized is used to heat the sensor element intermediate, heating is performed by heat conduction, heat radiation, or the like. Therefore, there exists a subject that the whole electrode is hard to be heated uniformly. As a result, there is a possibility that a sensor element having necessary performance cannot be obtained.
　特許文献１に記載されたコイルは、主体金具を加熱するものであり、センサ素子の中間体の加熱に用いるものではない。また、特許文献２に記載された誘導コイルは、ガスセンサの使用時にセンサ素子を加熱するものであり、センサ素子の中間体の加熱に用いるものではない。従って、センサ素子の中間体を加熱する際に、電極又は多孔質セラミック層の全体を、できるだけ均一にかつ短時間で加熱するためには、更なる工夫が必要とされる。 The coil described in Patent Document 1 heats the metal shell and is not used to heat the intermediate of the sensor element. Moreover, the induction coil described in Patent Document 2 heats the sensor element when the gas sensor is used, and is not used for heating the intermediate body of the sensor element. Therefore, when heating the intermediate body of the sensor element, in order to heat the electrode or the entire porous ceramic layer as uniformly as possible in a short time, further ingenuity is required.
　本開示は、必要な性能を有するセンサ素子を、精度よくかつ短時間で得ることができるガスセンサの製造用加熱装置を提供しようとするものである。 The present disclosure is intended to provide a heating device for manufacturing a gas sensor capable of obtaining a sensor element having necessary performance with high accuracy and in a short time.
　本開示の一態様は、内燃機関の排ガス（Ｇ）におけるガス検出を行うガスセンサ（４）に用いられ、固体電解質体（５１）に外側電極（５２Ａ）及び内側電極（５２Ｂ）が設けられたセンサ素子（５）の製造時に使用され、
　前記ガスセンサの制御装置（４０）とは別の通電制御ユニット（２）によって制御されて、前記センサ素子の中間体（５０）を加熱する製造用加熱装置（１）であって、
　前記通電制御ユニットと、
　前記中間体の周りに螺旋状に配置され、前記通電制御ユニットによる通電及び通電の遮断を受けて生じる電磁誘導によって前記中間体における前記外側電極及び前記内側電極を発熱させる誘導加熱コイル（３）と、を備える、ガスセンサの製造用加熱装置にある。 One aspect of the present disclosure is used in a gas sensor (4) that performs gas detection in exhaust gas (G) of an internal combustion engine, and includes a solid electrolyte body (51) provided with an outer electrode (52A) and an inner electrode (52B). Used in the manufacture of the element (5),
A heating apparatus (1) for manufacturing which is controlled by an energization control unit (2) different from the control apparatus (40) of the gas sensor and heats the intermediate body (50) of the sensor element,
The energization control unit;
An induction heating coil (3) arranged in a spiral around the intermediate body and generating heat to the outer electrode and the inner electrode in the intermediate body by electromagnetic induction generated by energization and interruption of energization by the energization control unit; And a heating device for manufacturing a gas sensor.
　前記ガスセンサの製造用加熱装置は、センサ素子の中間体を加熱して、センサ素子を製造するために用いられる。製造用加熱装置は、通電制御ユニットと、中間体の周りに螺旋状に配置される誘導加熱コイルとを備える。通電制御ユニットによって、中間体の周りに配置された誘導加熱コイルが通電されるときには、電磁誘導によって中間体における電極に渦電流が生じ、この渦電流によって電極が自己発熱する。これにより、電極の全体が極力均一に短時間で加熱され、これに伴い、電極の周辺も極力均一に短時間で加熱される。 The heating device for manufacturing the gas sensor is used for manufacturing a sensor element by heating an intermediate body of the sensor element. The manufacturing heating apparatus includes an energization control unit and an induction heating coil arranged in a spiral around the intermediate body. When the induction heating coil arranged around the intermediate body is energized by the energization control unit, an eddy current is generated in the electrode in the intermediate body by electromagnetic induction, and the electrode self-heats due to this eddy current. Thereby, the whole electrode is heated as uniformly as possible in a short time, and accordingly, the periphery of the electrode is also heated as uniformly as possible in a short time.
　そして、電極を焼結させるとき、電極の熱処理を行うとき、電極の表面を覆う多孔質セラミック層を乾燥又は焼結させるとき等において、中間体の電極の全体を極力均一に短時間で加熱することができ、必要な性能を有するセンサ素子を精度よく得ることができる。
　それ故、前記ガスセンサの製造用加熱装置によれば、必要な性能を有するセンサ素子を、精度よくかつ短時間で得ることができる。 When the electrode is sintered, when the electrode is heat-treated, when the porous ceramic layer covering the surface of the electrode is dried or sintered, the entire intermediate electrode is heated as uniformly as possible in a short time. Therefore, a sensor element having necessary performance can be obtained with high accuracy.
Therefore, according to the heating device for manufacturing the gas sensor, a sensor element having necessary performance can be obtained accurately and in a short time.
　なお、ガスセンサによる「ガス検出」が示す内容は、内燃機関から排気される排ガスの酸素濃度を検出すること、排ガスから求められる内燃機関の空燃比を検出すること、排ガスから求められる内燃機関の空燃比が、理論空燃比に対して燃料リッチ側にあるか燃料リーン側にあるかを検出すること、ＮＯｘ等の特定ガス成分の濃度を検出すること等を含む。 It should be noted that “gas detection” by the gas sensor indicates that the oxygen concentration of the exhaust gas exhausted from the internal combustion engine is detected, the air-fuel ratio of the internal combustion engine obtained from the exhaust gas is detected, and the air condition of the internal combustion engine obtained from the exhaust gas is detected. This includes detecting whether the fuel ratio is on the fuel rich side or the fuel lean side with respect to the stoichiometric air-fuel ratio, detecting the concentration of a specific gas component such as NOx, and the like.
　また、「製造用加熱装置」は、ガスセンサに内蔵された、加熱装置としてのヒータとは異なる。「ガスセンサの制御装置」は、ガスセンサによってガス検出を行う際に用いられる制御装置のことを示し、「通電制御ユニット」は、センサ素子を製造する際に用いられる制御装置のことを示す。「中間体における電極」には、焼結前の電極及び焼結後の電極のいずれも含まれる。 Also, the “heating device for manufacturing” is different from the heater as the heating device built in the gas sensor. “Gas sensor control device” indicates a control device used when gas detection is performed by a gas sensor, and “energization control unit” indicates a control device used when a sensor element is manufactured. The “electrode in the intermediate” includes both an electrode before sintering and an electrode after sintering.
　また、本開示の一態様において示す各構成要素のカッコ書きの符号は、実施形態における図中の符号との対応関係を示すが、各構成要素を実施形態の内容のみに限定するものではない。 In addition, although the reference numerals in parentheses of the constituent elements shown in one aspect of the present disclosure indicate the correspondence with the reference numerals in the drawings in the embodiments, the constituent elements are not limited only to the contents of the embodiments.
　また、ガスセンサの製造用加熱装置を用いることによって、次のガスセンサの製造方法を実現することができる。
　製造方法の発明の一態様としては、固体電解質体の両表面に電極がそれぞれ設けられ、内燃機関の排ガスにおけるガス検出を行うガスセンサに用いられるセンサ素子を製造するに当たり、
　前記固体電解質体の両表面に、電極を形成するための電極材料を配置する電極材料配置工程と、
　前記センサ素子の中間体の周りに螺旋状に配置される誘導加熱コイルと、前記誘導加熱コイルに通電を行う通電制御ユニットとを用い、前記通電制御ユニットから前記誘導加熱コイルへの通電及び通電の遮断を受けて生じる電磁誘導によって前記電極材料を発熱させて、前記電極材料から前記電極を形成する電極形成工程と、を含む、ガスセンサの製造方法がある。 Moreover, the following manufacturing method of a gas sensor is realizable by using the heating apparatus for manufacturing a gas sensor.
As one aspect of the invention of the manufacturing method, in manufacturing a sensor element used for a gas sensor in which electrodes are provided on both surfaces of a solid electrolyte body and gas detection in exhaust gas of an internal combustion engine is performed,
An electrode material arranging step of arranging an electrode material for forming an electrode on both surfaces of the solid electrolyte body;
Using an induction heating coil arranged in a spiral around the intermediate body of the sensor element and an energization control unit for energizing the induction heating coil, the energization and energization of the induction heating coil from the energization control unit is performed. There is a gas sensor manufacturing method including an electrode forming step of forming the electrode from the electrode material by causing the electrode material to generate heat by electromagnetic induction generated by being interrupted.
　また、製造方法の発明の他の態様としては、固体電解質体の両表面に電極がそれぞれ設けられ、かついずれかの外側電極の表面が多孔質セラミック層によって覆われ、内燃機関の排ガスにおけるガス検出を行うガスセンサに用いられるセンサ素子を製造するに当たり、
　前記外側電極の表面を含む前記センサ素子の中間体の表面に、前記多孔質セラミック層を形成するためのセラミック材料を配置するセラミック材料配置工程と、
　前記中間体の周りに螺旋状に配置される誘導加熱コイルと、前記誘導加熱コイルに通電を行う通電制御ユニットとを用い、前記通電制御ユニットから前記誘導加熱コイルへの通電及び通電の遮断を受けて生じる電磁誘導によって前記外側電極を発熱させ、前記外側電極から前記セラミック材料への熱伝導によって前記セラミック材料から前記多孔質セラミック層を形成するセラミック層形成工程と、を含む、ガスセンサの製造方法がある。 As another aspect of the invention of the manufacturing method, electrodes are provided on both surfaces of the solid electrolyte body, and the surface of one of the outer electrodes is covered with a porous ceramic layer, so that gas detection in exhaust gas from an internal combustion engine is performed. In manufacturing a sensor element used for a gas sensor that performs
A ceramic material disposing step of disposing a ceramic material for forming the porous ceramic layer on a surface of the sensor element intermediate including the surface of the outer electrode;
Using an induction heating coil arranged in a spiral around the intermediate body and an energization control unit for energizing the induction heating coil, the energization control unit is energized and the energization is interrupted. And a ceramic layer forming step of forming the porous ceramic layer from the ceramic material by heat conduction from the outer electrode to the ceramic material. is there.
　本開示についての目的、特徴、利点等は、添付の図面を参照する下記の詳細な記述により、より明確になる。本開示の図面を以下に示す。
実施形態１にかかる、製造用加熱装置を示す説明図。 実施形態１にかかる、センサ素子の中間体及び誘導加熱コイルの周辺を拡大して示す断面図。 実施形態１にかかる、ガスセンサを示す断面図。 実施形態１にかかる、センサ素子を示す断面図。 実施形態１にかかる、センサ素子の製造方法を示すフローチャート。 実施形態１にかかる、他のセンサ素子の製造方法を示すフローチャート。 実施形態１にかかる、センサ素子の中間体及び誘導加熱コイルの周辺を拡大して示す断面図。 実施形態１にかかる、実施品、比較品１及び比較品２の加熱装置によって中間体を目標温度に加熱するときの中間体の温度の変化を簡易的に示すグラフ。 実施形態２にかかる、製造用加熱装置を示す説明図。 実施形態２にかかる、焼結前後における一対の電極間の電気抵抗の違いを示すグラフ。 実施形態２にかかる、断線の有無に応じた一対の電極間の電気抵抗の違いを示すグラフ。 実施形態３にかかる、製造用加熱装置を示す説明図。 実施形態４にかかる、製造用加熱装置を示す説明図。 実施形態５にかかる、製造用加熱装置を示す説明図。 実施形態５にかかる、センサ素子の中間体及び誘導加熱コイルの周辺を示す説明図。 Objects, features, advantages, and the like of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawings of the present disclosure are shown below.
BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the heating apparatus for manufacture concerning Embodiment 1. FIG. Sectional drawing which expands and shows the periphery of the intermediate body and induction heating coil of a sensor element concerning Embodiment 1. FIG. 1 is a cross-sectional view showing a gas sensor according to a first embodiment. FIG. 3 is a cross-sectional view showing the sensor element according to the first embodiment. 3 is a flowchart showing a method for manufacturing a sensor element according to the first embodiment. 5 is a flowchart showing another sensor element manufacturing method according to the first embodiment. Sectional drawing which expands and shows the periphery of the intermediate body and induction heating coil of a sensor element concerning Embodiment 1. FIG. The graph which shows simply the change of the temperature of an intermediate body when heating an intermediate body to target temperature with the heating apparatus of the implementation goods, the comparative goods 1, and the comparative goods 2 concerning Embodiment 1. FIG. Explanatory drawing which shows the heating apparatus for manufacture concerning Embodiment 2. FIG. The graph which shows the difference of the electrical resistance between a pair of electrodes before and behind sintering concerning Embodiment 2. FIG. The graph which shows the difference of the electrical resistance between a pair of electrodes according to Embodiment 2 according to the presence or absence of a disconnection. Explanatory drawing which shows the heating apparatus for manufacture concerning Embodiment 3. FIG. Explanatory drawing which shows the heating apparatus for manufacture concerning Embodiment 4. FIG. Explanatory drawing which shows the heating apparatus for manufacture concerning Embodiment 5. FIG. Explanatory drawing which shows the periphery of the intermediate body of an sensor element, and induction heating coil concerning Embodiment 5. FIG.
　前述したガスセンサの製造用加熱装置にかかる好ましい実施形態について、図面を参照して説明する。
＜実施形態１＞
　本形態のガスセンサ４の製造用加熱装置１は、図１に示すように、ガスセンサ４に用いられるセンサ素子５を製造する際に用いられる。図３及び図４に示すように、ガスセンサ４は、内燃機関の排ガスＧにおけるガス検出を行うものであり、センサ素子５は、固体電解質体５１の両表面に電極５２Ａ，５２Ｂがそれぞれ設けられたものである。製造用加熱装置１は、図１及び図２に示すように、センサ素子５の製造時に、完成体となる前のセンサ素子５の中間体５０を加熱するものである。製造用加熱装置１は、ガスセンサ４の制御装置４０とは別に設けられた通電制御ユニット２と、中間体５０の周りに螺旋状に配置され、通電制御ユニット２による通電及び通電の遮断を受けて生じる電磁誘導によって中間体５０における電極５２Ａ，５２Ｂを発熱させる誘導加熱コイル３とを備える。 A preferred embodiment of the above-described heating apparatus for manufacturing a gas sensor will be described with reference to the drawings.
<Embodiment 1>
The heating device 1 for manufacturing the gas sensor 4 of this embodiment is used when manufacturing a sensor element 5 used for the gas sensor 4 as shown in FIG. As shown in FIGS. 3 and 4, the gas sensor 4 performs gas detection in the exhaust gas G of the internal combustion engine, and the sensor element 5 is provided with electrodes 52A and 52B on both surfaces of the solid electrolyte body 51, respectively. Is. As shown in FIG. 1 and FIG. 2, the manufacturing heating apparatus 1 heats the intermediate body 50 of the sensor element 5 before becoming a complete body when the sensor element 5 is manufactured. The manufacturing heating device 1 is arranged in a spiral around the energization control unit 2 and the intermediate body 50 provided separately from the control device 40 of the gas sensor 4, and receives energization and interruption of energization by the energization control unit 2. And an induction heating coil 3 that generates heat in the electrodes 52A and 52B in the intermediate 50 by electromagnetic induction that occurs.
　以下に、本形態のガスセンサ４の製造用加熱装置１について詳説する。
　本形態の製造用加熱装置１は、センサ素子５の製造時に用いられ、ガスセンサ４の使用時にセンサ素子５を加熱する用途には用いられない。製造用加熱装置１は、センサ素子５の製造時においてガスセンサ４と独立して動作する。本形態のガスセンサ４は、図３に示すように、センサ素子５を加熱するためのヒータを有しないヒータレスタイプのものであり、ヒータによってセンサ素子５を加熱することはできないものである。なお、製造用加熱装置１は、ヒータを内蔵するガスセンサ４に用いられるセンサ素子５を製造する際に使用してもよい。 Below, it demonstrates in full detail about the heating apparatus 1 for manufacture of the gas sensor 4 of this form.
The manufacturing heating apparatus 1 of this embodiment is used when manufacturing the sensor element 5 and is not used for heating the sensor element 5 when the gas sensor 4 is used. The manufacturing heating apparatus 1 operates independently of the gas sensor 4 when the sensor element 5 is manufactured. As shown in FIG. 3, the gas sensor 4 of this embodiment is a heaterless type that does not have a heater for heating the sensor element 5, and the sensor element 5 cannot be heated by the heater. In addition, you may use the heating apparatus 1 for manufacture, when manufacturing the sensor element 5 used for the gas sensor 4 incorporating a heater.
　センサ素子５の中間体５０は、センサ素子５の製造が完了する前の状態のものとする。センサ素子５の中間体５０としては、固体電解質体５１の両表面に焼結前の電極５２Ａ，５２Ｂが設けられた状態のもの、固体電解質体５１の両表面に熱処理前の電極５２Ａ，５２Ｂが設けられた状態のもの、固体電解質体５１の外側電極５２Ａの表面に乾燥前又は焼結前の多孔質セラミック層５３が設けられた状態のもの等がある。そして、製造用加熱装置１によって、中間体５０の電極５２Ａ，５２Ｂが発熱したときには、電極５２Ａ，５２Ｂの焼結もしくは熱処理、又は多孔質セラミック層５３の乾燥もしくは焼結を行うことができる。 The intermediate body 50 of the sensor element 5 is in a state before the manufacture of the sensor element 5 is completed. As the intermediate body 50 of the sensor element 5, a state in which the electrodes 52 A and 52 B before sintering are provided on both surfaces of the solid electrolyte body 51, and the electrodes 52 A and 52 B before heat treatment are formed on both surfaces of the solid electrolyte body 51. There are a state in which the porous ceramic layer 53 before drying or sintering is provided on the surface of the outer electrode 52A of the solid electrolyte body 51, and the like. Then, when the electrodes 52A and 52B of the intermediate body 50 generate heat by the manufacturing heating device 1, the electrodes 52A and 52B can be sintered or heat-treated, or the porous ceramic layer 53 can be dried or sintered.
　図１に示すように、製造用加熱装置１によって加熱する、センサ素子５の中間体５０は、電極５２Ａ，５２Ｂが設けられた固体電解質体５１の単体とすることができる。また、図１３に示すように、中間体５０は、電極５２Ａ，５２Ｂが設けられた固体電解質体５１であって、ガスセンサ４の各部品に組み付けられた状態のものとすることもできる。ただし、中間体５０が組み付けられたガスセンサ４の各部品は、後述する素子用カバー４４が取り外された状態のものとする。 As shown in FIG. 1, the intermediate body 50 of the sensor element 5 heated by the manufacturing heating apparatus 1 can be a single body of the solid electrolyte body 51 provided with the electrodes 52A and 52B. Further, as shown in FIG. 13, the intermediate body 50 is a solid electrolyte body 51 provided with electrodes 52 </ b> A and 52 </ b> B, and may be in a state assembled to each component of the gas sensor 4. However, each part of the gas sensor 4 to which the intermediate body 50 is assembled is assumed to be in a state where an element cover 44 described later is removed.
　本形態のガスセンサ４は、ヒータを内蔵しないヒータレスタイプのものであり、二輪自動車に搭載されるものである。ガスセンサ４は、二輪自動車における内燃機関の排気系統の配管に配置され、配管を流れる排ガスＧにおけるガス検出を行うものである。本形態のガスセンサ４は、排ガスＧ中の酸素を検出し、排ガスＧから求められる内燃機関の空燃比が、理論空燃比に対して燃料リッチ側にあるか燃料リーン側にあるかを検出するものである。なお、ガスセンサ４は、排ガスＧから求められる内燃機関の空燃比を検出するもの、又はＮＯｘ等の特定ガス成分の濃度を検出するものとしてもよい。 The gas sensor 4 of this embodiment is a heaterless type that does not incorporate a heater, and is mounted on a two-wheeled vehicle. The gas sensor 4 is disposed in a pipe of an exhaust system of an internal combustion engine in a two-wheeled vehicle, and detects gas in the exhaust gas G flowing through the pipe. The gas sensor 4 of this embodiment detects oxygen in the exhaust gas G, and detects whether the air-fuel ratio of the internal combustion engine obtained from the exhaust gas G is on the fuel rich side or the fuel lean side with respect to the theoretical air fuel ratio. It is. The gas sensor 4 may be one that detects the air-fuel ratio of the internal combustion engine obtained from the exhaust gas G, or one that detects the concentration of a specific gas component such as NOx.
（センサ素子５）
　図４に示すように、センサ素子５の固体電解質体５１は、有底円筒形状に形成されており、円筒部５１１と円筒部５１１の先端側を閉塞する半球状の底部５１２とを有する。電極５２Ａ，５２Ｂには、固体電解質体５１の外周面に設けられ、排ガスＧが接触する外側電極５２Ａと、固体電解質体５１の内周面に設けられ、大気Ａが接触する内側電極５２Ｂとがある。 (Sensor element 5)
As shown in FIG. 4, the solid electrolyte body 51 of the sensor element 5 is formed in a bottomed cylindrical shape, and includes a cylindrical portion 511 and a hemispherical bottom portion 512 that closes the distal end side of the cylindrical portion 511. The electrodes 52A and 52B include an outer electrode 52A provided on the outer peripheral surface of the solid electrolyte body 51 and in contact with the exhaust gas G, and an inner electrode 52B provided on the inner peripheral surface of the solid electrolyte body 51 and in contact with the atmosphere A. is there.
　図３及び図４に示すように、外側電極５２Ａは、固体電解質体５１の円筒部５１１の外周面における、底部５１２の近傍に位置する底側位置に設けられている。内側電極５２Ｂは、固体電解質体５１の円筒部５１１の内周面における全体に設けられている。センサ素子５の検出部５０１は、固体電解質体５１を介して外側電極５２Ａと内側電極５２Ｂとが対向する部位として形成されている。固体電解質体５１の円筒部５１１の外周面には、円筒部５１１の軸線方向Ｌに平行な状態で外側電極５２Ａに繋がる電極リード部５２１が形成されている。電極リード部５２１は、外側電極５２Ａには含まれないこととする。 As shown in FIGS. 3 and 4, the outer electrode 52A is provided on the outer peripheral surface of the cylindrical portion 511 of the solid electrolyte body 51 at the bottom position located in the vicinity of the bottom portion 512. The inner electrode 52 </ b> B is provided on the entire inner peripheral surface of the cylindrical portion 511 of the solid electrolyte body 51. The detection portion 501 of the sensor element 5 is formed as a portion where the outer electrode 52A and the inner electrode 52B face each other with the solid electrolyte body 51 interposed therebetween. On the outer peripheral surface of the cylindrical portion 511 of the solid electrolyte body 51, an electrode lead portion 521 connected to the outer electrode 52A in a state parallel to the axial direction L of the cylindrical portion 511 is formed. The electrode lead portion 521 is not included in the outer electrode 52A.
　固体電解質体５１は、酸化物イオン（Ｏ2-）を透過させる性質を有するジルコニア材料から構成されている。ジルコニア材料は、ジルコニアを主成分とする種々の材料によって構成することができる。ジルコニア材料には、希土類金属元素もしくはアルカリ土類金属元素によってジルコニアの一部を置換させた安定化ジルコニア又は部分安定化ジルコニアを用いることができる。外側電極５２Ａ及び内側電極５２Ｂは、酸素に対して反応する酸素活性触媒としての白金と、固体電解質体５１との共材となるジルコニア材料とを含有する。 The solid electrolyte body 51 is made of a zirconia material having a property of transmitting oxide ions (O 2− ). A zirconia material can be comprised with the various material which has a zirconia as a main component. As the zirconia material, stabilized zirconia or partially stabilized zirconia in which a part of zirconia is substituted with a rare earth metal element or an alkaline earth metal element can be used. The outer electrode 52 </ b> A and the inner electrode 52 </ b> B contain platinum as an oxygen active catalyst that reacts with oxygen and a zirconia material that is a co-material of the solid electrolyte body 51.
　図４に示すように、外側電極５２Ａの表面には、外側電極５２Ａを覆い、水及び被毒物質の透過を阻止して外側電極５２Ａを保護するための多孔質セラミック層５３が設けられている。多孔質セラミック層５３は、外側電極５２Ａを含む、固体電解質体５１の円筒部５１１の底側位置及び底部５１２の全周に設けられている。多孔質セラミック層５３は、アルミナ等のセラミック材料の多孔質体によって形成されている。 As shown in FIG. 4, a porous ceramic layer 53 is provided on the surface of the outer electrode 52A so as to cover the outer electrode 52A and prevent the permeation of water and poisonous substances to protect the outer electrode 52A. . The porous ceramic layer 53 is provided on the bottom side position of the cylindrical portion 511 of the solid electrolyte body 51 and the entire circumference of the bottom portion 512 including the outer electrode 52A. The porous ceramic layer 53 is formed of a porous body of a ceramic material such as alumina.
（ガスセンサ４）
　図３に示すように、ガスセンサ４は、センサ素子５の他に、センサ素子５を保持するハウジング４１、センサ素子５の各電極５２Ａ，５２Ｂに電気的に接続された接続端子４２及びリード線４３、センサ素子５の検出部５０１を覆う素子用カバー４４、接続端子４２及びリード線４３の一部を覆う端子用カバー４５等を備える。接続端子４２には、外側電極５２Ａの電極リード部５２１に外周側から接触するものと、内側電極５２Ｂに内周側から接触するものとがある。 (Gas sensor 4)
As shown in FIG. 3, in addition to the sensor element 5, the gas sensor 4 includes a housing 41 that holds the sensor element 5, connection terminals 42 and lead wires 43 that are electrically connected to the electrodes 52 </ b> A and 52 </ b> B of the sensor element 5. , An element cover 44 covering the detection portion 501 of the sensor element 5, a connection terminal 42, a terminal cover 45 covering a part of the lead wire 43, and the like. The connection terminal 42 includes one that contacts the electrode lead portion 521 of the outer electrode 52A from the outer peripheral side and one that contacts the inner electrode 52B from the inner peripheral side.
　素子用カバー４４には、排ガスＧが通過する貫通孔４４１が設けられている。排気系統の配管内を流れる排ガスＧは、貫通孔４４１を通って素子用カバー４４内に流入し、センサ素子５の検出部５０１における多孔質セラミック層５３及び外側電極５２Ａへ導かれる。また、端子用カバー４５には、大気Ａが通過する貫通孔４５１が設けられており、貫通孔４５１には、端子用カバー４５内に水が入ることを防止するシート４５２が対向して配置されている。排気系統の配管の外部に存在する大気Ａは、貫通孔４５１を通って端子用カバー４５内に流入し、センサ素子５の検出部５０１における内側電極５２Ｂへ導かれる。 The element cover 44 is provided with a through hole 441 through which the exhaust gas G passes. The exhaust gas G flowing in the piping of the exhaust system flows into the element cover 44 through the through hole 441 and is guided to the porous ceramic layer 53 and the outer electrode 52A in the detection portion 501 of the sensor element 5. Further, the terminal cover 45 is provided with a through hole 451 through which the atmosphere A passes, and a sheet 452 for preventing water from entering the terminal cover 45 is disposed facing the through hole 451. ing. The atmosphere A existing outside the piping of the exhaust system flows into the terminal cover 45 through the through hole 451 and is guided to the inner electrode 52 </ b> B in the detection unit 501 of the sensor element 5.
（誘導加熱コイル３）
　図１及び図２に示すように、誘導加熱コイル３の螺旋状部３１は、有底円筒形状の固体電解質体５１の円形断面形状に合わせて、円形状に形成されている。誘導加熱コイル３は、固体電解質体５１の円筒部５１１の全周に設けられた外側電極５２Ａの全周に対向して配置される。誘導加熱コイル３は、外側電極５２Ａの全体と、外側電極５２Ａに固体電解質体５１を介して対向する内側電極５２Ｂの部分とを発熱させるよう構成されている。誘導加熱コイル３を構成する導体３０１は、冷媒Ｃを通過させる冷媒流路３０２を内部に有する中空形状に形成されている。 (Induction heating coil 3)
As shown in FIGS. 1 and 2, the spiral portion 31 of the induction heating coil 3 is formed in a circular shape in accordance with the circular sectional shape of the bottomed cylindrical solid electrolyte body 51. The induction heating coil 3 is disposed to face the entire circumference of the outer electrode 52 </ b> A provided on the entire circumference of the cylindrical portion 511 of the solid electrolyte body 51. The induction heating coil 3 is configured to heat the entire outer electrode 52A and the portion of the inner electrode 52B that faces the outer electrode 52A via the solid electrolyte body 51. The conductor 301 constituting the induction heating coil 3 is formed in a hollow shape having a refrigerant flow path 302 through which the refrigerant C passes.
　誘導加熱コイル３が通電されるときには、誘導加熱コイル３はジュール熱によって発熱する。そこで、冷媒流路３０２を有する導体３０１を用いて誘導加熱コイル３を形成することにより、冷媒流路３０２に流れる冷媒Ｃによって誘導加熱コイル３を冷却し、誘導加熱コイル３が溶断することを防止することができる。これにより、誘導加熱コイル３によって、中間体５０における電極５２Ａ，５２Ｂが４００～１０００℃の高温になるまで、電極５２Ａ，５２Ｂを発熱させることができる。 When the induction heating coil 3 is energized, the induction heating coil 3 generates heat due to Joule heat. Therefore, by forming the induction heating coil 3 using the conductor 301 having the refrigerant flow path 302, the induction heating coil 3 is cooled by the refrigerant C flowing through the refrigerant flow path 302, and the induction heating coil 3 is prevented from fusing. can do. Thus, the induction heating coil 3 can cause the electrodes 52A and 52B to generate heat until the electrodes 52A and 52B in the intermediate 50 reach a high temperature of 400 to 1000 ° C.
　誘導加熱コイル３は、円環状断面を有する導体３０１が螺旋状に巻かれて形成されたものである。誘導加熱コイル３における螺旋状部３１の軸線方向Ｌの長さは、外側電極５２Ａの軸線方向Ｌの長さよりも長い。この構成により、誘導加熱コイル３によって外側電極５２Ａの全体を効果的に発熱させることができる。そして、誘導加熱コイル３の中心部には、外側電極５２Ａの軸線方向Ｌの全体が配置される。螺旋状部３１の軸線方向Ｌとは、螺旋状部３１の円中心を通る中心軸線が伸びる方向のことをいう。 The induction heating coil 3 is formed by spirally winding a conductor 301 having an annular cross section. The length of the spiral portion 31 in the induction heating coil 3 in the axial direction L is longer than the length of the outer electrode 52A in the axial direction L. With this configuration, the entire outer electrode 52A can be effectively heated by the induction heating coil 3. Then, the entire axial direction L of the outer electrode 52 </ b> A is disposed at the center of the induction heating coil 3. The axial direction L of the spiral portion 31 refers to the direction in which the central axis passing through the circle center of the spiral portion 31 extends.
　図２に示すように、誘導加熱コイル３を構成する導体３０１の外径は、φ１．５～３ｍｍの範囲内にあり、冷媒流路３０２の内径は、誘導加熱コイル３の外径よりも小さく、φ１～２．５ｍｍの範囲内にある。この構成により、センサ素子５の中間体５０を加熱するために最適な誘導加熱コイル３を形成することができ、中間体５０における電極５２Ａ，５２Ｂを４００～１０００℃の高温に加熱することが容易である。 As shown in FIG. 2, the outer diameter of the conductor 301 constituting the induction heating coil 3 is in the range of φ1.5 to 3 mm, and the inner diameter of the refrigerant flow path 302 is smaller than the outer diameter of the induction heating coil 3. , In the range of φ1 to 2.5 mm. With this configuration, the induction heating coil 3 that is optimal for heating the intermediate body 50 of the sensor element 5 can be formed, and the electrodes 52A and 52B in the intermediate body 50 can be easily heated to a high temperature of 400 to 1000 ° C. It is.
　導体３０１の外径がφ１．５ｍｍ未満である場合、又は冷媒流路３０２の内径がφ１ｍｍ未満である場合には、冷媒流路３０２の断面積が小さくなり、冷媒流路３０２を形成することが難しくなる。導体３０１の外径がφ３ｍｍ超過の場合、又は冷媒流路３０２の内径がφ２．５ｍｍ超過である場合には、センサ素子５に対して導体３０１及び冷媒流路３０２が相対的に大きくなり、外側電極５２Ａに対向させる導体３０１の巻き数を増やすことができなくなる。 When the outer diameter of the conductor 301 is less than φ1.5 mm, or when the inner diameter of the refrigerant flow path 302 is less than φ1 mm, the cross-sectional area of the refrigerant flow path 302 becomes small and the refrigerant flow path 302 may be formed. It becomes difficult. When the outer diameter of the conductor 301 exceeds φ3 mm, or when the inner diameter of the refrigerant flow path 302 exceeds φ2.5 mm, the conductor 301 and the refrigerant flow path 302 become relatively large with respect to the sensor element 5, and the outside It becomes impossible to increase the number of turns of the conductor 301 opposed to the electrode 52A.
　また、誘導加熱コイル３は、その中心軸線を中心とする径方向に導体３０１が１層巻の状態で配置され、導体３０１が螺旋状に３巻以上巻かれて形成されている。誘導加熱コイル３における導体３０１の巻き数は、例えば、１０巻以下とすることができる。また、誘導加熱コイル３を構成する導体３０１同士の間には、導体３０１同士の間の十分な絶縁性を確保するための隙間が形成されている。 Further, the induction heating coil 3 is formed by arranging the conductor 301 in a state of one layer winding in the radial direction around the central axis, and winding the conductor 301 three or more times in a spiral shape. The number of turns of the conductor 301 in the induction heating coil 3 can be, for example, 10 or less. In addition, a gap is formed between the conductors 301 constituting the induction heating coil 3 to ensure sufficient insulation between the conductors 301.
　図１に示すように、誘導加熱コイル３の両端部３２は、加熱ヘッド２１に支持されている。加熱ヘッド２１は、センサ素子５の中間体５０を保持する治具１１との間の位置決めができるよう構成されている。加熱ヘッド２１と治具１１との位置決めにより、センサ素子５の中間体５０と誘導加熱コイル３との位置決めを行い、中間体５０の中心軸線が誘導加熱コイル３の中心軸線と一致するようにする。 As shown in FIG. 1, both end portions 32 of the induction heating coil 3 are supported by the heating head 21. The heating head 21 is configured to be positioned with respect to the jig 11 that holds the intermediate body 50 of the sensor element 5. By positioning the heating head 21 and the jig 11, the intermediate body 50 of the sensor element 5 and the induction heating coil 3 are positioned so that the central axis of the intermediate body 50 coincides with the central axis of the induction heating coil 3. .
　図２に示すように、中間体５０の中心軸線と誘導加熱コイル３の中心軸線とが一致するときには、中間体５０の最も外周側の表面と、誘導加熱コイル３の内周側位置との間に形成される隙間Ｓが２ｍｍ以下になるようにしている。中間体５０の最も外周側の表面は、多孔質セラミック層５３が形成される前の中間体５０を加熱するときには、外側電極５２Ａの表面とすることができ、多孔質セラミック層５３が形成された後の中間体５０を加熱するときには、多孔質セラミック層５３の表面とすることができる。 As shown in FIG. 2, when the central axis of the intermediate body 50 and the central axis of the induction heating coil 3 coincide with each other, the distance between the outermost surface of the intermediate body 50 and the inner peripheral side position of the induction heating coil 3 The gap S formed on the substrate is 2 mm or less. When the intermediate body 50 is heated before the porous ceramic layer 53 is formed, the outermost surface of the intermediate body 50 can be the surface of the outer electrode 52A, and the porous ceramic layer 53 is formed. When the subsequent intermediate 50 is heated, the surface of the porous ceramic layer 53 can be used.
（通電制御ユニット２）
　図１に示すように、本形態の通電制御ユニット２は、誘導加熱コイル３の冷媒流路３０２に冷媒Ｃを循環させる冷却チラー２２と、中間体５０の底部５１２の温度を測定する温度計２４と、誘導加熱コイル３へ交流電圧（又は交流電流）を印加するコントローラ２３と、冷却チラー２２及びコントローラ２３へ電力を供給する電源（図示略）とを備える。冷媒Ｃは、冷却チラー２２から加熱ヘッド２１を経由して誘導加熱コイル３へ供給され、誘導加熱コイル３から加熱ヘッド２１を経由して冷却チラー２２へ回収される。コントローラ２３によって発生させる交流電圧は、正弦波、パルス波等の電圧波形を有するものとする。 (Energization control unit 2)
As shown in FIG. 1, the energization control unit 2 of this embodiment includes a cooling chiller 22 that circulates the refrigerant C through the refrigerant flow path 302 of the induction heating coil 3 and a thermometer 24 that measures the temperature of the bottom 512 of the intermediate body 50. And a controller 23 that applies an alternating voltage (or alternating current) to the induction heating coil 3, and a power source (not shown) that supplies power to the cooling chiller 22 and the controller 23. The refrigerant C is supplied from the cooling chiller 22 to the induction heating coil 3 via the heating head 21, and is collected from the induction heating coil 3 to the cooling chiller 22 via the heating head 21. The AC voltage generated by the controller 23 has a voltage waveform such as a sine wave or a pulse wave.
　冷却チラー２２は、誘導加熱コイル３の冷媒流路３０２に循環させる冷媒Ｃを冷却する機能を有する。温度計２４は、センサ素子５の中間体５０からの電磁波の移動による熱放射（熱輻射）を非接触で測定する放射温度計とする。センサ素子５の中間体５０の周りに誘導加熱コイル３が配置された状態において、中間体５０の底部５１２の先端には、誘導加熱コイル３の一部が対向しない。そこで、温度計２４は、中間体５０の底部５１２の先端に対向して配置し、底部５１２の先端からの熱放射による温度を非接触で測定する。 The cooling chiller 22 has a function of cooling the refrigerant C circulated through the refrigerant flow path 302 of the induction heating coil 3. The thermometer 24 is a radiation thermometer that measures heat radiation (heat radiation) due to movement of electromagnetic waves from the intermediate body 50 of the sensor element 5 in a non-contact manner. In a state where the induction heating coil 3 is disposed around the intermediate body 50 of the sensor element 5, a part of the induction heating coil 3 does not face the tip of the bottom 512 of the intermediate body 50. Therefore, the thermometer 24 is disposed so as to face the tip of the bottom 512 of the intermediate body 50, and measures the temperature due to heat radiation from the tip of the bottom 512 in a non-contact manner.
　コントローラ２３は、コンピュータを用いて構成されている。コントローラ２３は、誘導加熱コイル３へ印加する交流電圧の振幅及び周波数を調整する機能、誘導加熱コイル３によって加熱対象である中間体５０を加熱する目標温度及び電圧印加時間を設定する機能、加熱対象である中間体５０の温度を監視する機能、中間体５０の温度が目標温度になるようフィードバック制御を行う機能等を有している。コントローラ２３においては、目標温度の設定、交流電圧の振幅、周波数及び印加時間の設定等が可能である。 The controller 23 is configured using a computer. The controller 23 has a function of adjusting the amplitude and frequency of the AC voltage applied to the induction heating coil 3, a function of setting a target temperature and a voltage application time for heating the intermediate body 50 to be heated by the induction heating coil 3, and a heating target A function of monitoring the temperature of the intermediate body 50, a function of performing feedback control so that the temperature of the intermediate body 50 becomes the target temperature, and the like. In the controller 23, setting of the target temperature, setting of the amplitude, frequency and application time of the AC voltage are possible.
　図１に示すように、冷却チラー２２、加熱ヘッド２１及び温度計２４は、コントローラ２３に接続されている。温度計２４によって測定される中間体５０の底部５１２の温度はコントローラ２３に送信される。誘導加熱コイル３の両端部３２は、加熱ヘッド２１を介してコントローラ２３に接続されている。そして、コントローラ２３によって誘導加熱コイル３に交流電圧が印加される。 As shown in FIG. 1, the cooling chiller 22, the heating head 21, and the thermometer 24 are connected to a controller 23. The temperature of the bottom 512 of the intermediate body 50 measured by the thermometer 24 is transmitted to the controller 23. Both end portions 32 of the induction heating coil 3 are connected to the controller 23 via the heating head 21. Then, an AC voltage is applied to the induction heating coil 3 by the controller 23.
　コントローラ２３は、温度計２４による測定温度が目標温度になるよう、誘導加熱コイル３に印加する交流電圧の振幅（大きさ）及び周波数を調整するよう構成されている。この構成により、中間体５０における電極５２Ａ，５２Ｂの温度が適切な温度になるよう制御することができる。そのため、ガス検出を行うために必要な性能を有するセンサ素子５を精度よく得ることができる。 The controller 23 is configured to adjust the amplitude (magnitude) and frequency of the AC voltage applied to the induction heating coil 3 so that the temperature measured by the thermometer 24 becomes the target temperature. With this configuration, the temperature of the electrodes 52A and 52B in the intermediate body 50 can be controlled to be an appropriate temperature. Therefore, the sensor element 5 having performance necessary for performing gas detection can be obtained with high accuracy.
　目標温度は、センサ素子５の中間体５０における電極５２Ａ，５２Ｂを焼結する場合、センサ素子５の中間体５０における電極５２Ａ，５２Ｂの熱処理を行う場合、センサ素子５の中間体５０の外周面に配置された多孔質セラミック層５３の乾燥又は焼結を行う場合等の各製造場面に応じて、適切な温度に設定する。 The target temperature is determined when the electrodes 52A and 52B in the intermediate body 50 of the sensor element 5 are sintered, or when the electrodes 52A and 52B in the intermediate body 50 of the sensor element 5 are heat-treated. The temperature is set to an appropriate temperature in accordance with each production scene such as when the porous ceramic layer 53 disposed in the substrate is dried or sintered.
　なお、誘導加熱コイル３へ印加する交流電圧の振幅及び周波数と、誘導加熱コイル３によって加熱される中間体５０の温度との関係が分かる場合等には、温度計２４は使用しなくてもよい。この場合には、中間体５０の温度は測定せず、コントローラ２３は、フィードフォワード制御によって中間体５０を目標とする温度に加熱することができる。 If the relationship between the amplitude and frequency of the alternating voltage applied to the induction heating coil 3 and the temperature of the intermediate 50 heated by the induction heating coil 3 is known, the thermometer 24 may not be used. . In this case, the temperature of the intermediate body 50 is not measured, and the controller 23 can heat the intermediate body 50 to a target temperature by feedforward control.
　次に、製造用加熱装置１を用いてガスセンサ４のセンサ素子５を製造する方法について説明する。
（電極５２Ａ，５２Ｂの形成）
　まず、固体電解質体５１の表面に電極５２Ａ，５２Ｂを形成する場合について説明する。電極５２Ａ，５２Ｂを形成するに当たっては、図５に示すように、電極材料配置工程Ｓ１及び電極形成工程Ｓ２を行って電極５２Ａ，５２Ｂを形成する。電極材料配置工程Ｓ１においては、固体電解質体５１の両表面に、電極５２Ａ，５２Ｂを形成するための電極材料を配置する。電極材料は、電極５２Ａ，５２Ｂを構成する白金等の貴金属粒子、固体電解質粒子及び溶媒等を含有するものとする。なお、電極材料は、貴金属のめっき処理を行うためのめっき材料としてもよい。 Next, a method for manufacturing the sensor element 5 of the gas sensor 4 using the manufacturing heating apparatus 1 will be described.
(Formation of electrodes 52A and 52B)
First, the case where the electrodes 52A and 52B are formed on the surface of the solid electrolyte body 51 will be described. In forming the electrodes 52A and 52B, as shown in FIG. 5, an electrode material arranging step S1 and an electrode forming step S2 are performed to form the electrodes 52A and 52B. In the electrode material arrangement step S1, electrode materials for forming the electrodes 52A and 52B are arranged on both surfaces of the solid electrolyte body 51. The electrode material includes precious metal particles such as platinum, solid electrolyte particles, a solvent, and the like that constitute the electrodes 52A and 52B. The electrode material may be a plating material for performing a precious metal plating process.
　次いで、電極形成工程Ｓ２においては、図１に示すように、固体電解質体５１に電極材料が配置された、センサ素子５の中間体５０を、誘導加熱コイル３の螺旋状部３１の内側に配置する。このとき、中間体５０の中心軸線を、螺旋状部３１の中心軸線と一致させる。また、中間体５０の底部５１２の先端に対向する位置に温度計２４を配置する。また、コントローラ２３においては、電極材料を加熱する目標温度、誘導加熱コイル３に印加する交流電圧の振幅、周波数、印加時間等を設定する。 Next, in the electrode forming step S2, as shown in FIG. 1, the intermediate body 50 of the sensor element 5 in which the electrode material is disposed on the solid electrolyte body 51 is disposed inside the spiral portion 31 of the induction heating coil 3. To do. At this time, the central axis of the intermediate body 50 is made to coincide with the central axis of the spiral portion 31. In addition, the thermometer 24 is disposed at a position facing the tip of the bottom 512 of the intermediate body 50. In the controller 23, the target temperature for heating the electrode material, the amplitude, frequency, application time, and the like of the AC voltage applied to the induction heating coil 3 are set.
　次いで、図２に示すように、コントローラ２３は、誘導加熱コイル３に交流電圧を印加するとともに、冷却チラー２２を動作させて、誘導加熱コイル３の冷媒流路３０２に冷媒Ｃを循環させる。誘導加熱コイル３の螺旋状部３１に交流電圧が印加されるときには、通電及び通電の遮断を受けて、誘導加熱コイル３の内周側を貫通する磁界Ｍが生じる。そして、中間体５０の電極材料においては、磁界Ｍを打ち消すための渦電流が生じ、この渦電流の発生によって電極材料が自己発熱する。これにより、外側電極５２Ａの電極材料の全体、及び外側電極５２Ａに対向する内側電極５２Ｂの部分における電極材料の全体が極力均一に加熱される。 Next, as shown in FIG. 2, the controller 23 applies an AC voltage to the induction heating coil 3 and operates the cooling chiller 22 to circulate the refrigerant C through the refrigerant flow path 302 of the induction heating coil 3. When an alternating voltage is applied to the spiral portion 31 of the induction heating coil 3, a magnetic field M penetrating the inner peripheral side of the induction heating coil 3 is generated in response to energization and interruption of energization. In the electrode material of the intermediate 50, an eddy current for canceling the magnetic field M is generated, and the electrode material self-heats due to the generation of the eddy current. Thereby, the entire electrode material of the outer electrode 52A and the entire electrode material in the portion of the inner electrode 52B facing the outer electrode 52A are heated as uniformly as possible.
　また、中間体５０における底部５１２の先端の温度は、温度計２４によって測定されており、コントローラ２３は、温度計２４によって測定される温度が目標温度になるよう、誘導加熱コイル３へ印加する交流電圧の振幅及び周波数を調整する。そして、このコントローラ２３による調整は、設定された印加時間の間行われる。なお、目標温度は、中間体５０の加熱としての電極材料の発熱が行われる間に、適宜変更することもできる。こうして、固体電解質体５１の表面に配置された電極材料が焼結し、固体電解質体５１の表面に電極５２Ａ，５２Ｂが形成される。 Further, the temperature of the tip of the bottom 512 in the intermediate body 50 is measured by the thermometer 24, and the controller 23 applies alternating current to the induction heating coil 3 so that the temperature measured by the thermometer 24 becomes the target temperature. Adjust the voltage amplitude and frequency. The adjustment by the controller 23 is performed for the set application time. Note that the target temperature can be changed as appropriate while the electrode material generates heat as the heating of the intermediate 50. Thus, the electrode material arranged on the surface of the solid electrolyte body 51 is sintered, and the electrodes 52A and 52B are formed on the surface of the solid electrolyte body 51.
　また、誘導加熱コイル３による中間体５０の加熱は、固体電解質体５１の表面に設けられた電極５２Ａ，５２Ｂの熱処理をするために行うこともできる。この場合にも、電極５２Ａ，５２Ｂの焼結を行った場合と同様に、誘導加熱コイル３によって電極５２Ａ，５２Ｂが自己発熱する。 Further, the heating of the intermediate body 50 by the induction heating coil 3 can also be performed to heat-treat the electrodes 52A and 52B provided on the surface of the solid electrolyte body 51. Also in this case, the electrodes 52A and 52B are self-heated by the induction heating coil 3 as in the case where the electrodes 52A and 52B are sintered.
（多孔質セラミック層５３の形成）
　次に、外側電極５２Ａの表面に多孔質セラミック層５３を形成する場合について説明する。多孔質セラミック層５３を形成するに当たっては、図６に示すように、セラミック材料配置工程Ｓ３及びセラミック層形成工程Ｓ４を行って多孔質セラミック層５３を形成する。セラミック材料配置工程Ｓ３においては、外側電極５２Ａの表面を含むセンサ素子５の中間体５０の表面に、多孔質セラミック層５３を形成するためのセラミック材料を配置する。セラミック材料は、アルミナ等のセラミック粒子、多数の孔を形成するための揮発剤、溶媒等を含有するスラリー状のものとする。 (Formation of porous ceramic layer 53)
Next, the case where the porous ceramic layer 53 is formed on the surface of the outer electrode 52A will be described. In forming the porous ceramic layer 53, as shown in FIG. 6, the ceramic material arranging step S3 and the ceramic layer forming step S4 are performed to form the porous ceramic layer 53. In the ceramic material arrangement step S3, a ceramic material for forming the porous ceramic layer 53 is arranged on the surface of the intermediate body 50 of the sensor element 5 including the surface of the outer electrode 52A. The ceramic material is in the form of a slurry containing ceramic particles such as alumina, a volatilizing agent for forming a large number of pores, a solvent, and the like.
　次いで、セラミック層形成工程Ｓ４においては、図７に示すように、固体電解質体５１及び電極５２Ａ，５２Ｂにセラミック材料が配置された、センサ素子５の中間体５０を、誘導加熱コイル３の螺旋状部３１の内側に配置する。そして、電極５２Ａ，５２Ｂを形成する場合と同様にして、冷却チラー２２の冷媒Ｃによって誘導加熱コイル３を冷却しつつ、誘導加熱コイル３によって電極５２Ａ，５２Ｂを発熱させる。また、コントローラ２３によって、温度計２４によって測定する中間体５０の温度が目標温度になるよう、誘導加熱コイル３へ印加する交流電圧の振幅及び周波数が調整される。 Next, in the ceramic layer forming step S4, as shown in FIG. 7, the intermediate body 50 of the sensor element 5 in which the ceramic material is disposed on the solid electrolyte body 51 and the electrodes 52A and 52B is replaced with the spiral shape of the induction heating coil 3. Arranged inside the portion 31. In the same manner as when the electrodes 52A and 52B are formed, the induction heating coil 3 cools the induction heating coil 3 with the refrigerant C of the cooling chiller 22, and the induction heating coil 3 causes the electrodes 52A and 52B to generate heat. Further, the controller 23 adjusts the amplitude and frequency of the AC voltage applied to the induction heating coil 3 so that the temperature of the intermediate 50 measured by the thermometer 24 becomes the target temperature.
　誘導加熱コイル３の電磁誘導によって外側電極５２Ａ及び内側電極５２Ｂが発熱するときには、外側電極５２Ａ及び内側電極５２Ｂからの熱伝導によってセラミック材料が加熱される。そして、セラミック材料が乾燥・固化して、多孔質セラミック層５３が形成される。このとき、セラミック材料は、外側電極５２Ａと接する内側部分が先に加熱されて乾燥・固化し、内側部分から外側部分に向けて順次熱伝導によって加熱されて乾燥・固化していく。セラミック材料が加熱されるときには、セラミック材料に含まれる水等の溶媒が蒸発することによってセラミック材料の内部圧力が上昇する。 When the outer electrode 52A and the inner electrode 52B generate heat due to electromagnetic induction of the induction heating coil 3, the ceramic material is heated by heat conduction from the outer electrode 52A and the inner electrode 52B. Then, the ceramic material is dried and solidified to form the porous ceramic layer 53. At this time, the inner part in contact with the outer electrode 52A is first heated and dried and solidified, and the ceramic material is sequentially heated from the inner part to the outer part by heat conduction to be dried and solidified. When the ceramic material is heated, the internal pressure of the ceramic material increases due to evaporation of a solvent such as water contained in the ceramic material.
　そして、セラミック材料の外側部分が乾燥・固化するときに、セラミック材料の外側部分が乾燥して固化していないことにより、セラミック材料の内側部分において生じた内部圧力を外側部分へ逃がすことができる。これにより、セラミック材料の内側部分に内部圧力が残留しにくく、セラミック材料から形成する多孔質セラミック層５３に、突沸による割れが生じにくくすることができる。 Further, when the outer portion of the ceramic material is dried and solidified, the outer portion of the ceramic material is not dried and solidified, so that the internal pressure generated in the inner portion of the ceramic material can be released to the outer portion. As a result, the internal pressure hardly remains in the inner portion of the ceramic material, and cracks due to bumping can hardly occur in the porous ceramic layer 53 formed from the ceramic material.
　一方、製造用加熱装置１ではなく、熱放射、熱伝導、対流等による加熱を行う従来の加熱装置を用いてセラミック材料を加熱する場合には、セラミック材料は、外側部分から先に乾燥・固化し、外側部分から内側部分に向けて順次熱伝導によって加熱されて乾燥・固化していく。この場合には、セラミック材料の内側部分に溶媒が残留したままセラミック材料の外側部分が乾燥・固化することになり、内側部分の冷媒Ｃが蒸発するときに、内側部分の内部圧力が上昇する。そのため、セラミック材料から形成する多孔質セラミック層５３に、突沸による割れが生じるおそれがある。 On the other hand, when the ceramic material is heated by using a conventional heating device that performs heating by heat radiation, heat conduction, convection, etc. instead of the manufacturing heating device 1, the ceramic material is dried and solidified first from the outer portion. Then, it is heated by heat conduction sequentially from the outer part to the inner part and dried and solidified. In this case, the outer part of the ceramic material is dried and solidified while the solvent remains in the inner part of the ceramic material, and when the refrigerant C of the inner part evaporates, the internal pressure of the inner part increases. Therefore, the porous ceramic layer 53 formed from the ceramic material may be cracked due to bumping.
　図８は、誘導加熱を利用する製造用加熱装置１（実施品）、ジュール熱を利用する加熱装置（比較品１）、及び加熱炉を利用する加熱装置（比較品２）によって中間体５０を目標温度に加熱するときの中間体５０の温度の変化を簡易的に示す。中間体５０の温度は、中間体５０を構成する固体電解質体５１の底部５１２の先端の温度とする。比較品１においては、加熱装置の一部を中間体５０に接触させた場合について示す。 FIG. 8 shows that the intermediate body 50 is manufactured by a manufacturing heating device 1 using induction heating (practical product), a heating device using Joule heat (comparative product 1), and a heating device using a heating furnace (comparative product 2). The change of the temperature of the intermediate body 50 when heating to target temperature is shown simply. The temperature of the intermediate body 50 is the temperature of the tip of the bottom 512 of the solid electrolyte body 51 constituting the intermediate body 50. In the comparative product 1, a case where a part of the heating device is brought into contact with the intermediate body 50 is shown.
　誘導加熱を利用する実施品によれば、ジュール熱を利用する比較品１に比べて、中間体５０を目標温度に加熱する時間を短縮することができる。実施品においては、外側電極５２Ａの全体、及び内側電極５２Ｂにおける、外側電極５２Ａとの対向部位の全体が自己発熱する。そのため、各電極５２Ａ，５２Ｂから固体電解質体５１の底部５１２への伝熱量が多くなり、加熱時間が短くなると考える。また、外側電極５２Ａの全体、及び内側電極５２Ｂにおける、外側電極５２Ａとの対向部位の全体を略均一に発熱させることができる。 According to the product using induction heating, the time for heating the intermediate 50 to the target temperature can be shortened as compared with the comparative product 1 using Joule heat. In the actual product, the entire outer electrode 52A and the entire portion of the inner electrode 52B facing the outer electrode 52A self-heats. Therefore, it is considered that the amount of heat transfer from each electrode 52A, 52B to the bottom 512 of the solid electrolyte body 51 is increased, and the heating time is shortened. In addition, the entire outer electrode 52A and the entire portion of the inner electrode 52B facing the outer electrode 52A can be caused to generate heat substantially uniformly.
　比較品１において、中間体５０と加熱装置とが接触している場合には、加熱装置からの熱伝導によって中間体５０が加熱される。この熱伝導は、電極５２Ａ，５２Ｂ又は固体電解質体５１の一部から全体に局所的に行われるため、加熱時間が長くなる。また、外側電極５２Ａの全体、及び内側電極５２Ｂにおける、外側電極５２Ａとの対向部位の全体を均一に加熱することは困難である。 In the comparative product 1, when the intermediate 50 and the heating device are in contact, the intermediate 50 is heated by heat conduction from the heating device. Since this heat conduction is locally performed from a part of the electrodes 52A, 52B or the solid electrolyte body 51, the heating time becomes long. In addition, it is difficult to uniformly heat the entire outer electrode 52A and the entire portion of the inner electrode 52B facing the outer electrode 52A.
　比較品１において、中間体５０と加熱装置とが接触していない場合には、加熱装置からの熱放射によって中間体５０が加熱される。この場合には、熱放射によって熱が電磁波によって運ばれるため、加熱時間が長くなる。また、比較品２においても、熱放射又は対流によって中間体５０を加熱するため、加熱時間が著しく長くなる。 In the comparative product 1, when the intermediate 50 is not in contact with the heating device, the intermediate 50 is heated by heat radiation from the heating device. In this case, the heat is carried by electromagnetic waves due to thermal radiation, so that the heating time becomes long. Moreover, also in the comparative product 2, since the intermediate body 50 is heated by thermal radiation or convection, the heating time is remarkably increased.
　このように、本形態のガスセンサ４の製造用加熱装置１においては、中間体５０における外側電極５２Ａの全体、及び内側電極５２Ｂにおける、外側電極５２Ａとの対向部位の全体を略均一に短時間で加熱することができる。これにより、目標とする状態の外側電極５２Ａ又は多孔質セラミック層５３を形成することができ、必要な性能を有するセンサ素子５を精度よく得ることができる。
　それ故、本形態の製造用加熱装置１によれば、必要な性能を有するセンサ素子５を、精度よくかつ短時間で得ることができる。 As described above, in the heating apparatus 1 for manufacturing the gas sensor 4 of the present embodiment, the entire outer electrode 52A in the intermediate body 50 and the entire portion facing the outer electrode 52A in the inner electrode 52B are substantially uniformly and in a short time. Can be heated. Thereby, the outer electrode 52A or the porous ceramic layer 53 in a target state can be formed, and the sensor element 5 having necessary performance can be obtained with high accuracy.
Therefore, according to the manufacturing heating apparatus 1 of this embodiment, the sensor element 5 having necessary performance can be obtained with high accuracy and in a short time.
＜実施形態２＞
　本形態のガスセンサ４の製造用加熱装置１においては、通電制御ユニット２の構成が実施形態１に示す通電制御ユニット２の構成と異なる。本形態の通電制御ユニット２は、図９に示すように、センサ素子５の中間体５０における、固体電解質体５１を介する外側電極５２Ａと内側電極５２Ｂとの間の電気抵抗を検出する抵抗検出部２５と、誘導加熱コイル３へ交流電圧を印加するコントローラ２３とを備える。コントローラ２３は、誘導加熱コイル３への通電を開始し、抵抗検出部２５による電気抵抗が所定の閾値以下になったことを検知して誘導加熱コイル３への通電を終了するよう構成されている。 <Embodiment 2>
In the heating apparatus 1 for manufacturing the gas sensor 4 of this embodiment, the configuration of the energization control unit 2 is different from the configuration of the energization control unit 2 shown in the first embodiment. As shown in FIG. 9, the energization control unit 2 of this embodiment includes a resistance detection unit that detects an electrical resistance between the outer electrode 52 </ b> A and the inner electrode 52 </ b> B through the solid electrolyte body 51 in the intermediate body 50 of the sensor element 5. 25 and a controller 23 for applying an AC voltage to the induction heating coil 3. The controller 23 is configured to start energizing the induction heating coil 3, detect that the electrical resistance by the resistance detection unit 25 has become a predetermined threshold value or less, and end energization to the induction heating coil 3. .
　抵抗検出部２５は、有底円筒形状の固体電解質体５１の外側電極５２Ａに繋がる電極リード部５２１と、内側電極５２Ｂにおける、底側とは反対側の開口側の端部とに接続される。本形態においても、実施形態１の場合と同様に、誘導加熱コイル３は加熱ヘッド２１に支持され、通電制御ユニット２は、冷却チラー２２及び電源を有する。コントローラ２３においては、誘導加熱コイル３へ印加する交流電圧の振幅、周波数及び印加時間等が設定される。 The resistance detector 25 is connected to the electrode lead 521 connected to the outer electrode 52A of the bottomed cylindrical solid electrolyte body 51 and the end of the inner electrode 52B on the opening side opposite to the bottom. Also in this embodiment, as in the case of the first embodiment, the induction heating coil 3 is supported by the heating head 21, and the energization control unit 2 has a cooling chiller 22 and a power source. In the controller 23, the amplitude, frequency, application time, and the like of the AC voltage applied to the induction heating coil 3 are set.
　固体電解質体５１を介する外側電極５２Ａと内側電極５２Ｂとの間の電気抵抗には、外側電極５２Ａ及び内側電極５２Ｂの内部抵抗、固体電解質体５１の内部抵抗、外側電極５２Ａ及び内側電極５２Ｂと固体電解質体５１との間の界面抵抗等が含まれる。この電気抵抗は、図１０及び図１１に示すように、固体電解質体５１の温度に関連し、固体電解質体５１の温度が高いほど低くなる。同各図においては、固体電解質体５１が室温（２０℃）から４００℃に加熱され、その後４００℃に維持されるときの電気抵抗の変化を示す。 The electrical resistance between the outer electrode 52A and the inner electrode 52B via the solid electrolyte body 51 includes the inner resistance of the outer electrode 52A and the inner electrode 52B, the inner resistance of the solid electrolyte body 51, the outer electrode 52A and the inner electrode 52B, and the solid Interface resistance between the electrolyte body 51 and the like are included. As shown in FIGS. 10 and 11, this electrical resistance is related to the temperature of the solid electrolyte body 51 and becomes lower as the temperature of the solid electrolyte body 51 is higher. In each of the figures, a change in electrical resistance when the solid electrolyte body 51 is heated from room temperature (20 ° C.) to 400 ° C. and then maintained at 400 ° C. is shown.
　本形態においては、図１０に示すように、センサ素子５の中間体５０における一対の電極５２Ａ，５２Ｂの焼結を行う際に、一対の電極５２Ａ，５２Ｂの間に任意の電流を流して電気抵抗を測定することにより、一対の電極５２Ａ，５２Ｂの焼結が正常に行われたか否かを確認する。焼結が行われていない一対の電極５２Ａ，５２Ｂの間の電気抵抗は、焼結が行われた一対の電極５２Ａ，５２Ｂの間の電気抵抗に比べて高い。そこで、焼結が行われた一対の電極５２Ａ，５２Ｂの間の電気抵抗に余裕率を加味して、焼結前又は焼結後の判別をするための閾値を設定する。なお、電気抵抗は、電圧、電流等の変化を測定し、電圧、電流等の変化に基づいて求めることができる。 In this embodiment, as shown in FIG. 10, when the pair of electrodes 52A and 52B in the intermediate body 50 of the sensor element 5 is sintered, an electric current is passed between the pair of electrodes 52A and 52B. By measuring the resistance, it is confirmed whether or not the pair of electrodes 52A and 52B has been normally sintered. The electrical resistance between the pair of electrodes 52A and 52B that has not been sintered is higher than the electrical resistance between the pair of electrodes 52A and 52B that has been sintered. Therefore, a threshold for determining before or after sintering is set by adding a margin to the electrical resistance between the pair of electrodes 52A and 52B subjected to sintering. The electrical resistance can be obtained based on changes in voltage, current, etc. by measuring changes in voltage, current, etc.
　本形態においても、誘導加熱コイル３への通電は、設定した印加時間が経過するまで行う。そして、この印加時間が経過したときには、電極５２Ａ，５２Ｂの焼結が正常に行われたかを確認するために、抵抗検出部２５によって一対の電極５２Ａ，５２Ｂの間の電気抵抗を測定する。この電気抵抗が、焼結の完了を示す閾値以下である場合には、焼結が正常に行われたとして、誘導加熱コイル３への通電を終了する。一方、電気抵抗が、焼結の完了を示す閾値以下でない場合には、焼結がまだ完了していないとして、誘導加熱コイル３への通電を継続する。そして、電気抵抗が閾値以下となったときに通電を終了する。こうして、本形態においては、電極５２Ａ，５２Ｂの焼結が正常に行われたか否かを確認することができ、センサ素子５の製造の精度を高めることができる。 Also in this embodiment, the induction heating coil 3 is energized until the set application time elapses. And when this application time passes, in order to confirm whether sintering of electrode 52A, 52B was performed normally, the electrical resistance between a pair of electrodes 52A, 52B is measured by the resistance detection part 25. FIG. When the electrical resistance is equal to or less than the threshold value indicating the completion of sintering, the energization to the induction heating coil 3 is terminated on the assumption that the sintering has been normally performed. On the other hand, when the electrical resistance is not less than or equal to the threshold value indicating the completion of sintering, the energization to the induction heating coil 3 is continued assuming that the sintering has not been completed yet. Then, energization is terminated when the electrical resistance is equal to or less than the threshold value. Thus, in this embodiment, it can be confirmed whether or not the electrodes 52A and 52B are normally sintered, and the accuracy of manufacturing the sensor element 5 can be increased.
　また、図１１に示すように、固体電解質体５１が４００℃に維持される状態において、一対の電極５２Ａ，５２Ｂの間に部分的な断線又は完全な断線がある場合の電気抵抗は、断線が生じていない場合の電気抵抗に比べて高くなる。そのため、印加時間よりも長い予備時間を経過しても、電気抵抗が閾値以下にならない場合には、一対の電極５２Ａ，５２Ｂの間に断線が生じていることを推定することができる。なお、断線は、電極５２Ａ，５２Ｂの剥離、電極５２Ａ，５２Ｂが薄くなったことによるかすれ、固体電解質体５１の欠け、割れ等によって生じる。 Further, as shown in FIG. 11, in the state where the solid electrolyte body 51 is maintained at 400 ° C., the electrical resistance in the case where there is a partial disconnection or a complete disconnection between the pair of electrodes 52A and 52B is the disconnection. It becomes higher than the electric resistance when it does not occur. Therefore, if the electrical resistance does not fall below the threshold value even after a preparatory time longer than the application time, it can be estimated that a disconnection has occurred between the pair of electrodes 52A and 52B. The disconnection occurs due to peeling of the electrodes 52A and 52B, fading due to the thinning of the electrodes 52A and 52B, chipping or cracking of the solid electrolyte body 51, and the like.
　本実施形態においても、製造用加熱装置１のその他の構成及び実施形態１に示した符号と同一の符号が示す構成要素は、実施形態１の場合と同様である。そして、実施形態１と同様の作用効果を得ることができる。 Also in the present embodiment, the other components of the manufacturing heating apparatus 1 and the components indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment. And the effect similar to Embodiment 1 can be acquired.
＜実施形態３＞
　本形態のガスセンサ４の製造用加熱装置１は、誘導加熱コイル３に通電を行う機能の他に、加熱が行われた後のセンサ素子５又は中間体５０が正常に機能するかの検査を行う機能を有する。本形態の通電制御ユニット２は、図１２に示すように、固体電解質体５１を介する外側電極５２Ａと内側電極５２Ｂとの間に流れる電流を検出する電流検出部２６と、電流検出部２６によって検出される電流が所定の閾値以上であるか否かを判定する判定部２７とを備える。 <Embodiment 3>
The heating device 1 for manufacturing the gas sensor 4 according to the present embodiment performs an inspection of whether the sensor element 5 or the intermediate body 50 after heating is functioning normally in addition to the function of energizing the induction heating coil 3. It has a function. As shown in FIG. 12, the energization control unit 2 of the present embodiment is detected by a current detection unit 26 that detects a current flowing between the outer electrode 52A and the inner electrode 52B via the solid electrolyte body 51, and a current detection unit 26. And a determination unit 27 that determines whether or not the current to be output is equal to or greater than a predetermined threshold value.
　電流検出部２６は、センサ素子５又は中間体５０の固体電解質体５１の外側電極５２Ａに接触させる流体Ｒ１の酸素濃度と、センサ素子５又は中間体５０の固体電解質体５１の内側電極５２Ｂに接触させる流体Ｒ２の酸素濃度とを異ならせたときに、外側電極５２Ａと内側電極５２Ｂとの間に流れる電流を検出する。判定部２７において使用される閾値は、外側電極５２Ａにおける酸素濃度と内側電極５２Ｂにおける酸素濃度との差に応じて、外側電極５２Ａと内側電極５２Ｂとの間に流れる電流に余裕率を加味して設定する。判定部２７は、コントローラ２３内に構成することができ、コントローラ２３とは別の制御装置によって構成することもできる。 The current detection unit 26 is in contact with the oxygen concentration of the fluid R1 to be brought into contact with the outer electrode 52A of the solid electrolyte body 51 of the sensor element 5 or the intermediate body 50 and the inner electrode 52B of the solid electrolyte body 51 of the sensor element 5 or the intermediate body 50. The current flowing between the outer electrode 52A and the inner electrode 52B is detected when the oxygen concentration of the fluid R2 to be made is different. The threshold value used in the determination unit 27 is determined by adding a margin to the current flowing between the outer electrode 52A and the inner electrode 52B according to the difference between the oxygen concentration in the outer electrode 52A and the oxygen concentration in the inner electrode 52B. Set. The determination unit 27 can be configured in the controller 23, or can be configured by a control device different from the controller 23.
　電流検出部２６は、有底円筒形状の固体電解質体５１の外側電極５２Ａに繋がる電極リード部５２１と、内側電極５２Ｂにおける、底側とは反対側の開口側の端部とに接続される。本形態においても、実施形態１の場合と同様に、誘導加熱コイル３は加熱ヘッド２１に支持され、通電制御ユニット２は、冷却チラー２２及び電源を有する。コントローラ２３においては、誘導加熱コイル３へ印加する交流電圧の振幅、周波数及び印加時間等が設定される。図１２においては、製造用加熱装置１の詳細を省略する。 The current detection unit 26 is connected to the electrode lead portion 521 connected to the outer electrode 52A of the bottomed cylindrical solid electrolyte body 51 and the end portion of the inner electrode 52B on the opening side opposite to the bottom side. Also in this embodiment, as in the case of the first embodiment, the induction heating coil 3 is supported by the heating head 21, and the energization control unit 2 has a cooling chiller 22 and a power source. In the controller 23, the amplitude, frequency, application time, and the like of the AC voltage applied to the induction heating coil 3 are set. In FIG. 12, the details of the manufacturing heating apparatus 1 are omitted.
　本形態においては、誘導加熱コイル３への通電が終了した後、外側電極５２Ａに接触させる流体Ｒ１の酸素濃度と、内側電極５２Ｂに接触させる流体Ｒ２の酸素濃度とを異ならせる。本形態においては、各電極５２Ａ，５２Ｂ及び固体電解質体５１が触媒活性を有する温度において、内側電極５２Ｂには、流体Ｒ２としての大気Ａを接触させ、外側電極５２Ａには、大気Ａよりも酸素濃度が低い、流体Ｒ１としての気体を接触させる。このとき、各電極５２Ａ，５２Ｂ及び固体電解質体５１が触媒活性を有する温度になるように、誘導加熱コイル３への通電によって各電極５２Ａ，５２Ｂ及び固体電解質体５１を加熱してもよい。 In this embodiment, after energization of the induction heating coil 3 is finished, the oxygen concentration of the fluid R1 brought into contact with the outer electrode 52A is made different from the oxygen concentration of the fluid R2 brought into contact with the inner electrode 52B. In this embodiment, at the temperature at which each of the electrodes 52A and 52B and the solid electrolyte body 51 has catalytic activity, the inner electrode 52B is brought into contact with the atmosphere A as the fluid R2, and the outer electrode 52A is more oxygenated than the atmosphere A. A gas as the fluid R1 having a low concentration is brought into contact. At this time, the electrodes 52A and 52B and the solid electrolyte body 51 may be heated by energizing the induction heating coil 3 so that the electrodes 52A and 52B and the solid electrolyte body 51 have a catalytic activity.
　外側電極５２Ａに接触する流体Ｒ１の酸素濃度と内側電極５２Ｂに接触する流体Ｒ２の酸素濃度との差により、酸化物イオン（Ｏ2-）が固体電解質体５１を透過し、外側電極５２Ａと内側電極５２Ｂとの間に電流が流れる。そこで、電流検出部２６によって外側電極５２Ａと内側電極５２Ｂとの間に流れる電流を測定する。そして、電流検出部２６によって測定される電流が閾値以上である場合には、判定部２７は、センサ素子５又は中間体５０が、ガス検出を行うために正常に機能するとして、このセンサ素子５又は中間体５０が良品であると判定する。 Due to the difference between the oxygen concentration of the fluid R1 in contact with the outer electrode 52A and the oxygen concentration of the fluid R2 in contact with the inner electrode 52B, oxide ions (O 2− ) permeate the solid electrolyte body 51 and A current flows between the electrode 52B. Therefore, the current flowing between the outer electrode 52A and the inner electrode 52B is measured by the current detection unit 26. When the current measured by the current detection unit 26 is equal to or greater than the threshold value, the determination unit 27 determines that the sensor element 5 or the intermediate body 50 functions normally in order to perform gas detection. Or it determines with the intermediate body 50 being non-defective.
　一方、電流検出部２６によって測定される電流が閾値未満である場合には、判定部２７は、センサ素子５又は中間体５０が、ガス検出を行うために正常に機能しないとして、このセンサ素子５又は中間体５０が不良品であると判定する。本形態においては、センサ素子５又は中間体５０がガス検出のために正常に機能するかを検査することができ、センサ素子５の製造の精度を高めることができる。 On the other hand, when the current measured by the current detection unit 26 is less than the threshold value, the determination unit 27 determines that the sensor element 5 or the intermediate body 50 does not function normally in order to perform gas detection. Or it determines with the intermediate body 50 being inferior goods. In this embodiment, it can be inspected whether the sensor element 5 or the intermediate body 50 functions normally for gas detection, and the manufacturing accuracy of the sensor element 5 can be increased.
　本実施形態においても、製造用加熱装置１のその他の構成及び実施形態１に示した符号と同一の符号が示す構成要素は、実施形態１の場合と同様である。そして、実施形態１と同様の作用効果を得ることができる。 Also in the present embodiment, the other components of the manufacturing heating apparatus 1 and the components indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment. And the effect similar to Embodiment 1 can be acquired.
＜実施形態４＞
　本形態においては、ハウジング４１等に組み付けられた状態のセンサ素子５によるガス検出が正常に機能するかを検査する際に製造用加熱装置１を用いる。図１３に示すように、本形態のセンサ素子５が組み付けられたガスセンサ４からは、素子用カバー４４（図３参照）が取り外されている。そして、製造用加熱装置１の誘導加熱コイル３によって、素子用カバー４４が取り外されたガスセンサ４におけるセンサ素子５を、一対の電極５２Ａ，５２Ｂ及び固体電解質体５１が触媒活性を有する温度に加熱する。また、外側電極５２Ａに接触させる流体の酸素濃度と、内側電極５２Ｂに接触させる流体の酸素濃度とを異ならせる。具体的には、内側電極５２Ｂには大気Ａを接触させ、外側電極５２Ａには大気Ａよりも酸素濃度が低い気体を接触させる。 <Embodiment 4>
In this embodiment, the manufacturing heating apparatus 1 is used when inspecting whether the gas detection by the sensor element 5 in a state assembled to the housing 41 or the like functions normally. As shown in FIG. 13, the element cover 44 (see FIG. 3) is removed from the gas sensor 4 to which the sensor element 5 of this embodiment is assembled. And the sensor element 5 in the gas sensor 4 from which the element cover 44 is removed is heated to a temperature at which the pair of electrodes 52A and 52B and the solid electrolyte body 51 have catalytic activity by the induction heating coil 3 of the manufacturing heating apparatus 1. . Further, the oxygen concentration of the fluid brought into contact with the outer electrode 52A is made different from the oxygen concentration of the fluid brought into contact with the inner electrode 52B. Specifically, the atmosphere A is brought into contact with the inner electrode 52B, and a gas having a lower oxygen concentration than the atmosphere A is brought into contact with the outer electrode 52A.
　本形態においても、電流検出部２６及び判定部２７を有する通電制御ユニット２を備えた、実施形態３の製造用加熱装置１を用いる。図１３においては、製造用加熱装置１の詳細を省略する。そして、電流検出部２６によって測定される電流が閾値以上である場合には、判定部２７は、ガスセンサ４が、ガス検出を行うために正常に機能するとして、このガスセンサ４が良品であると判定する。一方、電流検出部２６によって測定される電流が閾値未満である場合には、判定部２７は、ガスセンサ４が、ガス検出を行うために正常に機能しないとして、このガスセンサ４が不良品であると判定する。判定部２７は、コントローラ２３内に構成することができ、コントローラ２３とは別の制御装置によって構成することもできる。 Also in the present embodiment, the manufacturing heating apparatus 1 of the third embodiment including the energization control unit 2 having the current detection unit 26 and the determination unit 27 is used. In FIG. 13, the details of the manufacturing heating apparatus 1 are omitted. When the current measured by the current detection unit 26 is equal to or greater than the threshold value, the determination unit 27 determines that the gas sensor 4 functions normally to perform gas detection, and determines that the gas sensor 4 is a non-defective product. To do. On the other hand, when the current measured by the current detection unit 26 is less than the threshold value, the determination unit 27 determines that the gas sensor 4 is defective because the gas sensor 4 does not function normally for gas detection. judge. The determination unit 27 can be configured in the controller 23, or can be configured by a control device different from the controller 23.
　本形態においては、ガスセンサ４が、通電によって発熱するヒータを内蔵しない場合において、製造用加熱装置１を用いて、ガスセンサ４におけるセンサ素子５を、ガスセンサ４の外部から加熱することができる。そのため、製造用加熱装置１を用いることにより、ヒータを内蔵しないヒータレスのガスセンサ４における機能検査を行うことができる。 In this embodiment, when the gas sensor 4 does not include a heater that generates heat when energized, the sensor element 5 in the gas sensor 4 can be heated from the outside of the gas sensor 4 using the manufacturing heating device 1. Therefore, by using the manufacturing heating apparatus 1, it is possible to perform a function test in the heaterless gas sensor 4 that does not incorporate a heater.
＜実施形態５＞
　本形態におけるセンサ素子５は、図１４及び図１５に示すように、板形状の固体電解質体５１に一対の電極５２Ａ，５２Ｂが設けられた積層タイプのものである。そして、一対の電極５２Ａ，５２Ｂには、固体電解質体５１の一方の表面に設けられ、排ガスＧが接触する外側電極５２Ａと、固体電解質体５１の他方の表面に設けられ、大気Ａが接触する内側電極５２Ｂとがある。外側電極５２Ａの表面には、外側電極５２Ａに到達する排ガスＧの流速を調整するための拡散抵抗層としての多孔質セラミック層５３が形成されている。 <Embodiment 5>
As shown in FIGS. 14 and 15, the sensor element 5 in this embodiment is of a laminated type in which a pair of electrodes 52 </ b> A and 52 </ b> B are provided on a plate-shaped solid electrolyte body 51. The pair of electrodes 52A and 52B is provided on one surface of the solid electrolyte body 51 and provided on the other surface of the solid electrolyte body 51 and the outer electrode 52A in contact with the exhaust gas G, and the atmosphere A is in contact therewith. There is an inner electrode 52B. On the surface of the outer electrode 52A, a porous ceramic layer 53 is formed as a diffusion resistance layer for adjusting the flow rate of the exhaust gas G reaching the outer electrode 52A.
　センサ素子５は、角部に面取り、フィレット加工等が行われた矩形状の断面を有する、長尺状の直方体形状に形成されている。一対の電極５２Ａ，５２Ｂは、長尺形状のセンサ素子５における先端部分に形成されている。センサ素子５の内部には、内側電極５２Ｂへ大気Ａを取り込むためのダクト５４が形成されている。また、本形態のセンサ素子５は、ヒータを内蔵しないものである。 The sensor element 5 is formed in an elongated rectangular parallelepiped shape having a rectangular cross-section with chamfered corners and fillet processing. The pair of electrodes 52 </ b> A and 52 </ b> B is formed at the distal end portion of the elongated sensor element 5. Inside the sensor element 5, a duct 54 for taking in the atmosphere A into the inner electrode 52B is formed. Moreover, the sensor element 5 of this embodiment does not include a heater.
　図１５に示すように、本形態の誘導加熱コイル３は、センサ素子５の矩形状の断面に合わせて、導体３０１が長円形状（オーバル形状）であって螺旋形状に巻かれて形成されている。誘導加熱コイル３は、長円形状の導体３０１における長辺部と、センサ素子５の表面との間の隙間Ｓが２ｍｍ以下になるよう形成されている。本形態の製造用加熱装置１のその他の構成は、実施形態１に示したものと同様である。 As shown in FIG. 15, the induction heating coil 3 of the present embodiment is formed by winding a conductor 301 in an oval shape (oval shape) and spirally in accordance with a rectangular cross section of the sensor element 5. Yes. The induction heating coil 3 is formed such that the gap S between the long side portion of the elliptical conductor 301 and the surface of the sensor element 5 is 2 mm or less. Other configurations of the manufacturing heating apparatus 1 of the present embodiment are the same as those shown in the first embodiment.
　本形態の製造用加熱装置１によれば、積層タイプのセンサ素子５を効果的に加熱することができ、必要な性能を有する積層タイプのセンサ素子５を、精度よくかつ短時間で得ることができる。 According to the manufacturing heating apparatus 1 of the present embodiment, the multilayer sensor element 5 can be effectively heated, and the multilayer sensor element 5 having necessary performance can be obtained accurately and in a short time. it can.
　なお、製造用加熱装置１の構成は、実施形態１～５に示したものに限られず、本開示の要旨を逸脱しない範囲においてさらに異なる実施形態を構成することが可能である。本開示は、様々な変形例や均等範囲内の変形例をも包含する。 The configuration of the manufacturing heating apparatus 1 is not limited to that shown in the first to fifth embodiments, and further different embodiments can be configured without departing from the gist of the present disclosure. The present disclosure includes various modifications and modifications within the equivalent range.

Claims (7)

  1. 　内燃機関の排ガス（Ｇ）におけるガス検出を行うガスセンサ（４）に用いられ、固体電解質体（５１）に外側電極（５２Ａ）及び内側電極（５２Ｂ）が設けられたセンサ素子（５）の製造時に使用され、
    　前記ガスセンサの制御装置（４０）とは別の通電制御ユニット（２）によって制御されて、前記センサ素子の中間体（５０）を加熱する製造用加熱装置（１）であって、
    　前記通電制御ユニットと、
    　前記中間体の周りに螺旋状に配置され、前記通電制御ユニットによる通電及び通電の遮断を受けて生じる電磁誘導によって前記中間体における前記外側電極及び前記内側電極を発熱させる誘導加熱コイル（３）と、を備える、ガスセンサの製造用加熱装置。     At the time of manufacture of the sensor element (5) used for the gas sensor (4) for detecting the gas in the exhaust gas (G) of the internal combustion engine and provided with the outer electrode (52A) and the inner electrode (52B) on the solid electrolyte body (51). Used,
    A heating apparatus (1) for manufacturing which is controlled by an energization control unit (2) different from the control apparatus (40) of the gas sensor and heats the intermediate body (50) of the sensor element,
    The energization control unit;
    An induction heating coil (3) arranged in a spiral around the intermediate body and generating heat to the outer electrode and the inner electrode in the intermediate body by electromagnetic induction generated by energization and interruption of energization by the energization control unit; A heating device for manufacturing a gas sensor.
  2. 　前記誘導加熱コイルは、有底円筒形状に形成された前記固体電解質体の、底側の外周面に設けられた前記外側電極の全周に対向して配置されて、少なくとも前記外側電極の全体を発熱させるよう構成されている、請求項１に記載のガスセンサの製造用加熱装置。 The induction heating coil is disposed so as to face the entire circumference of the outer electrode provided on the outer peripheral surface of the bottom side of the solid electrolyte body formed in a bottomed cylindrical shape, and at least the entire outer electrode is disposed. The heating device for manufacturing a gas sensor according to claim 1, wherein the heating device is configured to generate heat.
  3. 　前記通電制御ユニットは、前記中間体の底部（５１２）の温度を測定する温度計（２４）と、前記誘導加熱コイルへ交流電圧を印加するコントローラ（２３）とを備えており、
    　前記コントローラは、前記温度計による測定温度が目標温度になるよう、前記交流電圧の振幅及び周波数を調整するよう構成されている、請求項１又は２に記載のガスセンサの製造用加熱装置。     The energization control unit includes a thermometer (24) for measuring the temperature of the bottom (512) of the intermediate body, and a controller (23) for applying an AC voltage to the induction heating coil,
    The heating device for manufacturing a gas sensor according to claim 1, wherein the controller is configured to adjust an amplitude and a frequency of the AC voltage so that a temperature measured by the thermometer becomes a target temperature.
  4. 　前記通電制御ユニットは、前記中間体における、前記固体電解質体を介する前記外側電極と前記内側電極との間の電気抵抗を検出する抵抗検出部（２５）と、前記誘導加熱コイルへ交流電圧を印加するコントローラ（２３）とを備えており、
    　前記コントローラは、前記誘導加熱コイルへの通電を開始し、前記抵抗検出部によって検出される電気抵抗が所定の閾値以下になったことを検知して前記誘導加熱コイルへの通電を終了する、請求項１又は２に記載のガスセンサの製造用加熱装置。     The energization control unit applies an AC voltage to the induction heating coil and a resistance detection unit (25) for detecting an electrical resistance between the outer electrode and the inner electrode through the solid electrolyte body in the intermediate body. And a controller (23) for
    The controller starts energizing the induction heating coil, detects that the electrical resistance detected by the resistance detection unit has become a predetermined threshold value or less, and ends energization to the induction heating coil. Item 3. A heating device for manufacturing a gas sensor according to Item 1 or 2.
  5. 　前記通電制御ユニットは、
    　前記センサ素子又は前記中間体の前記固体電解質体の前記外側電極に接触させる流体（Ｒ１）の酸素濃度と、前記センサ素子又は前記中間体の前記固体電解質体の前記内側電極に接触させる流体（Ｒ２）の酸素濃度とを異ならせたときに、前記固体電解質体を介する前記外側電極と前記内側電極との間に流れる電流を検出する電流検出部（２６）と、
    　前記電流検出部によって検出される電流が所定の閾値以上であるか否かを判定する判定部（２７）と、を備える、請求項１～４のいずれか１項に記載のガスセンサの製造用加熱装置。     The energization control unit is
    The oxygen concentration of the fluid (R1) in contact with the outer electrode of the solid electrolyte body of the sensor element or the intermediate body and the fluid (R2) of contact with the inner electrode of the solid electrolyte body of the sensor element or the intermediate body And a current detector (26) for detecting a current flowing between the outer electrode and the inner electrode via the solid electrolyte body when the oxygen concentration is different from
    The heating for manufacturing a gas sensor according to any one of claims 1 to 4, further comprising: a determination unit (27) that determines whether or not a current detected by the current detection unit is equal to or greater than a predetermined threshold value. apparatus.
  6. 　前記誘導加熱コイルを構成する導体（３０１）は、冷媒（Ｃ）を通過させる冷媒流路（３０２）を内部に有する中空形状に形成されており、
    　前記通電制御ユニットは、前記冷媒流路に冷媒を循環させる冷却チラー（２２）を備える、請求項１～５のいずれか１項に記載のガスセンサの製造用加熱装置。     The conductor (301) constituting the induction heating coil is formed in a hollow shape having a refrigerant flow path (302) through which the refrigerant (C) passes,
    The heating device for manufacturing a gas sensor according to any one of claims 1 to 5, wherein the energization control unit includes a cooling chiller (22) that circulates the refrigerant in the refrigerant flow path.
  7. 　前記誘導加熱コイルを構成する導体の外径は、φ１．５～３ｍｍの範囲内にあり、前記冷媒流路の内径は、前記誘導加熱コイルの外径よりも小さく、φ１～２．５ｍｍの範囲内にあり、
    　前記誘導加熱コイルの全長は、前記固体電解質体の軸線方向（Ｌ）における、前記外側電極の全長よりも長い、請求項６に記載のガスセンサの製造用加熱装置。     The outer diameter of the conductor constituting the induction heating coil is in the range of φ1.5 to 3 mm, and the inner diameter of the refrigerant flow path is smaller than the outer diameter of the induction heating coil and in the range of φ1 to 2.5 mm. In
    The heating device for manufacturing a gas sensor according to claim 6, wherein an overall length of the induction heating coil is longer than an overall length of the outer electrode in an axial direction (L) of the solid electrolyte body.
PCT/JP2018/004077 2017-02-09 2018-02-06 Heating device for manufacturing gas sensor WO2018147287A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4890294A (en) * 1972-02-10 1973-11-24
JPH10300714A (en) * 1997-04-23 1998-11-13 Robert Bosch Gmbh Measuring instrument
JP2006105768A (en) * 2004-10-05 2006-04-20 Denso Corp Gas sensor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4890294A (en) * 1972-02-10 1973-11-24
JPH10300714A (en) * 1997-04-23 1998-11-13 Robert Bosch Gmbh Measuring instrument
JP2006105768A (en) * 2004-10-05 2006-04-20 Denso Corp Gas sensor

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