Film strength measurement method

Abstract

SOLUTION: A film strength measurement method measures strength of a protective film 30 covering a front end part of an element body 20. The method includes the steps of: pressing a rear part of the protective film with a jig 50 so that force in a direction from a rear end part to the front end part of the element body is applied to the rear part of the protective film; and measuring the strength of the protective film on the basis of strength of force when the protective film is separated from the element body by the jig. First inclined surfaces 341-344 are present on portions of the protective film with which the jig contacts while second inclined surfaces 831-834 facing the first inclined surfaces are present on portions of the jig with which the protective film contacts.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for measuring film strength. [Background technology]

[0002] Patent Document 1 discloses a sensor element capable of measuring the concentration of nitrogen oxides (NOx) and the like in a measurement gas. A part of the sensor element is covered with a protective film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-65852 A Summary of the Invention [Problem to be solved by the invention]

[0004] Such a protective film needs to be resistant to vibration, impact, etc. For this reason, the strength of the protective film is often measured. However, there are cases where the strength of the protective film cannot be measured satisfactorily.

[0005] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] A film strength measurement method according to one embodiment of the present invention is a film strength measurement method for measuring the strength of a protective film covering a front end, which is one end in the longitudinal direction of an element body that constitutes a sensor element, and includes the steps of pressing the rear end of the protective film with a jig so that a force is applied to the rear end of the protective film in a direction from the rear end, which is the other end in the longitudinal direction of the element body, toward the front end, and measuring the strength of the protective film based on the magnitude of force when the protective film is peeled off from the element body by the jig, wherein at the portion of the protective film with which the jig abuts, there is a first inclined surface that is inclined with respect to the longitudinal direction due to the thickness of the protective film decreasing as it approaches the rear end of the protective film, and at the portion of the jig with which the protective film abuts, there is a second inclined surface that faces the first inclined surface and is inclined with respect to the longitudinal direction. Effect of the Invention

[0007] According to the present invention, it is possible to provide a film strength measuring method capable of satisfactorily measuring the strength of a protective film. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view showing a sensor element. [Diagram 2] FIG. 2 is a cross-sectional view showing a sensor element. [Diagram 3] FIG. 3A is a top view showing the sensor element, the jig, and the holder, and FIG. 3B is a side view showing the sensor element, the jig, and the holder. [Figure 4] FIG. 2 is a schematic diagram showing a film strength measuring device. [Diagram 5] FIG. 11 is a diagram showing the relationship between the size of a through hole and the size of a sensor element. [Figure 6] 6A and 6B are diagrams showing how the sensor element and the jig are moved relative to each other. [Figure 7] 1 is a graph showing the relationship between angle difference and film strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [One embodiment] Before describing a film strength measuring method according to an embodiment, an example of a sensor element for measuring film strength will be described. Fig. 1 is a perspective view showing the sensor element. Fig. 2 is a cross-sectional view showing the sensor element. Fig. 2 corresponds to the cross section taken along line AA' in Fig. 1. That is, Fig. 2 is a cross-sectional view taken along the longitudinal direction of the sensor element.

[0010] As shown in FIG. 1, the sensor element 10 is shaped, for example, as a long rectangular parallelepiped. The sensor element 10 is housed, for example, in a housing (not shown) of a gas sensor (not shown). The gas sensor is attached, for example, to a pipe (not shown). An example of the pipe is an exhaust gas pipe of a vehicle. The gas sensor is used to measure the concentration of a specific gas contained in exhaust gas or the like, which is a gas to be measured. Examples of the specific gas include, but are not limited to, nitrogen oxides and oxygen (O2).

[0011] The sensor element 10 includes an element body 20 and a protective film 30 that covers a part of the element body 20 .

[0012] The longitudinal direction of the element body 20 is defined as the front-rear direction. That is, the left-right direction on the paper surface of FIG. 2 is defined as the front-rear direction. The thickness direction of the element body 20 is defined as the up-down direction. That is, the up-down direction on the paper surface of FIG. 2 is defined as the up-down direction. The width direction of the element body 20 is defined as the left-right direction. That is, the direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction. The central axis of the element body 20 coincides with the longitudinal direction of the element body 20.

[0013] As shown in FIG. 2, the element body 20 has a laminate 12 consisting of a plurality of layers 60, 62, 64, 66, 68, and 70. A second substrate layer 62 is laminated on a first substrate layer 60. A solid electrolyte layer 64 is laminated on the second substrate layer 62. A solid electrolyte layer 66 is laminated on the solid electrolyte layer 64. A spacer layer 68 is laminated on the solid electrolyte layer 66. A solid electrolyte layer 70 is laminated on the spacer layer 68. For example, a solid electrolyte is used as the material of these layers 60, 62, 64, 66, 68, and 70. More specifically, an oxygen ion conductive solid electrolyte is used as the material of these layers 60, 62, 64, 66, 68, and 70. For example, zirconia (ZrO2) or the like can be used as the oxygen ion conductive solid electrolyte.

[0014] The element body 20 has a rectangular parallelepiped shape. Therefore, as shown in FIG. 1, the element body 20 has six faces (surfaces) 201 to 206. The face 201 is a first main face that is one of the main faces of the element body 20. The face 202 is a second main face that is the other main face of the element body 20. The face 203 is the right side face of the element body 20. The face 204 is the left side face of the element body 20. The face 205 is the rear end face of the element body 20. The face 206 is the front end face of the element body 20. The length of the element body 20 is, for example, 25 mm or more and 100 mm or less, but is not limited thereto. The width of the element body 20 is, for example, 2 mm or more and 10 mm or less, but is not limited thereto. The thickness of the element body 20 is, for example, 0.5 mm or more and 5 mm or less, but is not limited thereto.

[0015] A measurement gas flow path (measurement gas flow section) 79 through which the measurement gas flows is formed inside the sensor element 10. The measurement gas flows in the measurement gas flow path 79 in the longitudinal direction of the measurement gas flow path 79. The measurement gas flow path 79 is formed in the spacer layer 68. That is, the measurement gas flow path 79 is configured by hollowing out a part of the spacer layer 68. The side of the measurement gas flow path 79 is defined by the spacer layer 68. The bottom surface (lower surface) of the measurement gas flow path 79 is defined by the upper surface of the solid electrolyte layer 66. The top surface (upper surface) of the measurement gas flow path 79 is defined by the lower surface of the solid electrolyte layer 70. One end of the measurement gas flow path 79 is a gas inlet 80, which is an inlet through which the measurement gas is introduced. That is, the left part of FIG. 2 is the gas inlet 80. The gas inlet 80 is provided in a portion of the element body 20 except for the rear end portion. More specifically, the gas inlet 80 is provided at the front end, which is one end of the element body 20 in the longitudinal direction.

[0016] In the measurement gas flow path 79, a first diffusion rate-controlling section 82 is provided at the rear of the gas inlet 80. The first diffusion rate-controlling section 82 is provided with, for example, two slits. The longitudinal direction of the slits is, for example, a direction perpendicular to the paper surface in FIG. 2. A buffer space 84 is provided at the rear of the first diffusion rate-controlling section 82. A second diffusion rate-controlling section 86 is provided at the rear of the buffer space 84. The second diffusion rate-controlling section 86 is provided with, for example, two slits. The longitudinal direction of the slits is, for example, a direction perpendicular to the paper surface in FIG. 2. A first internal space 88 is provided at the rear of the second diffusion rate-controlling section 86. The first internal space 88 is in communication with the buffer space 84 via the second diffusion rate-controlling section 86. A third diffusion rate-controlling section 90 is provided at the rear of the first internal space 88. The third diffusion rate-controlling section 90 is provided with, for example, two slits. The longitudinal direction of the slit is, for example, a direction perpendicular to the paper surface in FIG. 2. A second internal space 92 is provided downstream of the third diffusion rate-controlling section 90. The second internal space 92 is connected to the first internal space 88 via the third diffusion rate-controlling section 90. A fourth diffusion rate-controlling section 94 is provided downstream of the second internal space 92. The fourth diffusion rate-controlling section 94 is provided with, for example, one slit. The longitudinal direction of the slit is, for example, a direction perpendicular to the paper surface in FIG. 2. A third internal space 96 is provided downstream of the fourth diffusion rate-controlling section 94. The third internal space 96 is connected to the second internal space 92 via the fourth diffusion rate-controlling section 94.

[0017] A reference gas introduction space 98 is formed inside the sensor element 10. The above-mentioned measurement gas flow path 79 is located at the front end of the sensor element 10. On the other hand, the reference gas introduction space 98 is located at the rear end of the sensor element 10. The reference gas introduction space 98 is configured by hollowing out a part of the solid electrolyte layer 66. The side of the reference gas introduction space 98 is defined by the solid electrolyte layer 66. The lower surface of the reference gas introduction space 98 is defined by the upper surface of the solid electrolyte layer 64. The upper surface of the reference gas introduction space 98 is defined by the lower surface of the spacer layer 68. A reference gas can be introduced into the reference gas introduction space 98. The atmosphere of a space (not shown) in the gas sensor can be the reference gas. The reference gas when measuring the concentration of nitrogen oxides is, for example, air.

[0018] An air introduction layer 100 is provided inside the sensor element 10. The air introduction layer 100 is provided, for example, between the solid electrolyte layer 64 and the solid electrolyte layer 66. A porous material is used as the material of the air introduction layer 100. More specifically, for example, porous ceramics such as porous alumina can be used as the material of the air introduction layer 100. A part of the air introduction layer 100 is exposed in the reference gas introduction space 98. A reference gas can be introduced into the air introduction layer 100 through the reference gas introduction space 98. The air introduction layer 100 is formed so as to cover a reference electrode 102 described later. The air introduction layer 100 allows the reference gas to reach the reference electrode 102 while providing a predetermined diffusion resistance to the reference gas in the reference gas introduction space 98. A rear end of the air introduction layer 100 is exposed in the reference gas introduction space 98. The part of the air introduction layer 100 that covers the reference electrode 102 is not exposed in the reference gas introduction space 98.

[0019] A reference electrode 102 is formed on the upper surface of the solid electrolyte layer 64. The planar shape of the reference electrode 102 is, for example, rectangular. The reference electrode 102 is formed directly on the solid electrolyte layer 64. A part of the reference electrode 102 is exposed in a reference gas chamber 182 in which a reference gas exists. An air introduction layer 100 exists in the reference gas chamber 182. Note that, here, an example will be described in which the air introduction layer 100 exists in the reference gas chamber 182, but the air introduction layer 100 does not have to exist in the reference gas chamber 182. That is, the reference gas chamber 182 may be empty. The air introduction layer 100 is formed so as to reach the reference gas introduction space 98. The reference gas chamber 182 may contain a reference gas introduced through the air introduction layer 100. A part of the reference electrode 102 other than the part in contact with the solid electrolyte layers 64, 66 is exposed in the reference gas chamber 182. As described below, the oxygen concentration (oxygen partial pressure) in the first internal space 88, the oxygen concentration in the second internal space 92, and the oxygen concentration in the third internal space 96 can be measured using a reference electrode 102. The reference electrode 102 can be made of, for example, a porous cermet. The cermet is a composite material of ceramics and metal. For example, the reference electrode 102 can be made of a cermet of platinum (Pt) and zirconia.

[0020] The gas inlet 80 is open to the external space. A measurement gas can be introduced into the sensor element 10 from the external space through the gas inlet 80. The first diffusion rate-controlling section 82 provides a predetermined diffusion resistance to the measurement gas introduced from the gas inlet 80. The buffer space 84 guides the measurement gas introduced from the first diffusion rate-controlling section 82 to the second diffusion rate-controlling section 86. The second diffusion rate-controlling section 86 provides a predetermined diffusion resistance to the measurement gas introduced from the buffer space 84 into the first internal space 88. The measurement gas introduced into the sensor element 10 through the gas inlet 80 is introduced into the first internal space 88 through the first diffusion rate-controlling section 82, the buffer space 84, and the second diffusion rate-controlling section 86.

[0021] A pump electrode 112 is disposed in the measurement gas flow path 79. The pump electrode 112 is disposed in the measurement gas flow path 79 along the flow direction of the measurement gas in the measurement gas flow path 79. The outer pump electrode 114 is formed on the upper surface of the solid electrolyte layer 70. That is, the outer pump electrode 114 is disposed on the first main surface 201 of the element body 20. The pump electrode 112 is formed on the inner surface of the first inner space 88. The outer pump electrode 114 is formed in an area corresponding to the area in which the pump electrode 112 is formed.

[0022] The pump electrode 112 may be configured by a plurality of electrodes formed on the bottom surface of the first inner space 88 and the top surface of the first inner space 88, for example.

[0023] The pump electrode 112 and the outer pump electrode 114 may be made of, for example, a porous cermet.

[0024] By applying a desired voltage between the pump electrode 112 and the outer pump electrode 114, a current flows in a positive or negative direction between the pump electrode 112 and the outer pump electrode 114. Accordingly, oxygen in the first inner space 88 can be pumped out to the external space, or oxygen in the external space can be pumped into the first inner space 88. As a result, the oxygen concentration in the first inner space 88 can be maintained at a predetermined constant value.

[0025] The third diffusion rate-controlling section 90 provides a predetermined diffusion resistance to the measurement gas introduced from the first internal space 88 to the second internal space 92, and guides the measurement gas to the second internal space 92. That is, the third diffusion rate-controlling section 90 provides a predetermined diffusion resistance to the measurement gas whose oxygen concentration is controlled.

[0026] The second internal space 92 is a space for further adjusting the oxygen concentration of the measurement gas whose oxygen concentration has been previously adjusted in the first internal space 88. That is, the oxygen concentration of the measurement gas introduced into the second internal space 92 via the third diffusion-controlling section 90 is further adjusted. Since the oxygen concentration in the second internal space 92 can be kept constant with high accuracy, the concentration of nitrogen oxides can be measured with high accuracy.

[0027] An auxiliary pump electrode 126 is formed on the inner surface of the second inner space 92. The auxiliary pump electrode 126 is formed in, for example, a cylindrical shape.

[0028] By applying a voltage between the auxiliary pump electrode 126 and the outer pump electrode 114, a pump current flows in a positive or negative direction between the auxiliary pump electrode 126 and the outer pump electrode 114. Accordingly, oxygen in the second internal space 92 can be pumped out to the external space, or oxygen in the external space can be pumped into the second internal space 92. In this manner, oxygen pumping can be performed. The oxygen partial pressure in the atmosphere in the second internal space 92 can be controlled to a low level that does not substantially affect the measurement of the concentration of nitrogen oxides.

[0029] The fourth diffusion rate-controlling section 94 provides a predetermined diffusion resistance to the measurement gas introduced from the second internal space 92 to the third internal space 96, and guides the measurement gas to the third internal space 96. That is, the fourth diffusion rate-controlling section 94 provides a predetermined diffusion resistance to the measurement gas whose oxygen concentration is controlled. The fourth diffusion rate-controlling section 94 also serves to limit the amount of nitrogen oxides flowing into the third internal space 96.

[0030] The measurement gas, the oxygen concentration of which has been adjusted in advance in the second internal space 92, is introduced into the third internal space 96 via the fourth diffusion rate-controlling section 94. The third internal space 96 is a space for detecting the concentration of nitrogen oxides in the measurement gas. That is, the third internal space 96 is a space for detecting the concentration of nitrogen oxides.

[0031] A measurement electrode 134 is formed on an upper surface of the solid electrolyte layer 66. For example, a porous cermet may be used as the material of the measurement electrode 134. The measurement electrode 134 functions as a catalyst for reducing nitrogen oxides present in the atmosphere in the third internal space 96.

[0032] The measurement gas introduced into the second internal space 92 reaches the measurement electrode 134 in the third internal space 96 through the fourth diffusion rate-controlling part 94 under the condition that the oxygen partial pressure is controlled. The nitrogen oxides in the measurement gas around the measurement electrode 134 are reduced by the measurement electrode 134 (2NO→N2+O2), and oxygen is generated around the measurement electrode 134. The oxygen generated around the measurement electrode 134 is pumped. The amount of oxygen generated around the measurement electrode 134 is proportional to the concentration of nitrogen oxides in the measurement gas. Therefore, the concentration of nitrogen oxides in the measurement gas can be calculated based on the pump current corresponding to the amount of oxygen pumped out by the pumping. In addition, the oxygen partial pressure in the measurement gas outside the sensor element 10 can be detected based on the electromotive force generated between the outer pump electrode 114 and the reference electrode 102.

[0033] In such a sensor element 10, the measurement gas is obtained in which the oxygen partial pressure is maintained at a constant low value. That is, the measurement gas is obtained in which the oxygen partial pressure is maintained at a value that does not substantially affect the measurement of the nitrogen oxide concentration. Then, an amount of oxygen approximately proportional to the concentration of nitrogen oxides in the measurement gas is generated by the reduction of nitrogen oxides. The oxygen thus generated is pumped out. Since a pump current flows according to the amount of oxygen pumped out by pumping, it is possible to detect the concentration of nitrogen oxides in the measurement gas based on the pump current.

[0034] The sensor element 10 further includes a heater section 160 for heating and keeping the sensor element 10 warm. The heater section 160 serves to adjust the temperature of the sensor element 10. By heating the solid electrolyte included in the sensor element 10, the oxygen ion conductivity of the solid electrolyte can be increased. The heater section 160 includes a heater 164, a through hole 166, a heater insulating layer 168, a pressure release hole 170, and a lead wire 172. The heater 164 is connected to the connector electrode 162 via the lead wire 172 and the through hole 166.

[0035] The connector electrode 162 is disposed on the lower surface of the first substrate layer 60. That is, the connector electrode 162 is disposed on the second main surface 202. By electrically connecting the connector electrode 162 to an external power supply, power can be supplied to the heater portion 160 from the external power supply.

[0036] The heater 164 is sandwiched between the second substrate layer 62 and the solid electrolyte layer 64 from above and below. The heater 164 is formed of, for example, an electric resistor. The heater 164 is connected to the connector electrode 162 via a lead wire 172 and a through hole 166. The heater 164 generates heat when power is supplied from the outside via the connector electrode 162. The heater 164 can heat and keep warm the solid electrolyte that forms the sensor element 10.

[0037] The heater insulating layer 168 is formed so as to cover the upper surface, lower surface, and side surfaces of the heater 164. For example, an insulator may be used as the material of the heater insulating layer 168. More specifically, for example, porous alumina may be used as the material of the heater insulating layer 168.

[0038] The pressure relief hole 170 penetrates the solid electrolyte layer 64 and the air introduction layer 100, and communicates with the reference gas introduction space 98. The pressure relief hole 170 is formed for the purpose of mitigating an increase in internal pressure that accompanies a temperature rise in the heater insulating layer 168.

[0039] Each of the multiple electrodes provided on the sensor element 10 is connected to a variable power supply (not shown) or the like via a connector electrode 162 or the like.

[0040] 1, the protective film 30 covers the front end portion of the element body 20. The protective film 30 covers each of the faces 201 to 204 and 206 of the element body 20.

[0041] 2, the protective film 30 includes, for example, an inner protective layer 321 and an outer protective layer 322 located on the outer side of the inner protective layer 321. Note that, although the protective film 30 having a two-layer structure will be described here as an example, the protective film 30 may have a single-layer structure.

[0042] The protective film 30 is made of, for example, a porous body. More specifically, the protective film 30 is made of, for example, a porous alumina film. The porosity of the inner protective layer 321 is, for example, 40% or more and 60% or less. The thickness of the inner protective layer 321 is, for example, 170 μm or more and 900 μm or less. The porosity of the outer protective layer 322 is, for example, 15% or more and 50% or less. The thickness of the outer protective layer 322 is, for example, 30 μm or more and 300 μm or less.

[0043] As shown in FIG. 1, the protective film 30 is composed of five portions 301 to 305. The portion (first portion) 301 covers the first main surface 201 of the element body 20. The portion (second portion) 302 covers the second main surface 202 of the element body 20. The portion (third portion) 303 covers the right side surface 203 of the element body 20. The portion (fourth portion) 304 covers the left side surface 204 of the element body 20. The portion (fifth portion) 305 covers the front end surface 206 of the element body 20. The protective film 30 can be formed by, for example, a plasma spraying method or the like, but is not limited thereto.

[0044] 2, the gas inlet 80 is covered with the protective film 30, which is made of a porous material as described above. Therefore, the measurement gas can reach the gas inlet 80 by flowing through the inside of the protective film 30.

[0045] In the rear part of the protective film 30, the thickness of the protective film 30 decreases toward the rear end of the protective film 30. Therefore, the protective film 30 has first inclined surfaces 341 to 344 inclined with respect to the longitudinal direction of the element body 20, as shown in Figs. 3A and 3B. Fig. 3A is a top view showing the sensor element, the jig, and the holder. Fig. 3B is a side view showing the sensor element, the jig, and the holder. Figs. 3A and 3B show a state in which a jig 50 described later and a holder 55 described later are attached to the sensor element 10. As shown in Figs. 3A and 3B, the first inclined surface 341 exists at the rear of the first portion 301. The first inclined surface 342 exists at the rear of the second portion 302. The first inclined surface 343 exists at the rear of the third portion 303. The first inclined surface 344 exists at the rear of the fourth portion 304. The first inclined surfaces 341 to 344 are inclined at a first angle θA with respect to the longitudinal direction of the element body 20. The first inclined surfaces 341 to 344 are present in a portion of the protective film 30 with which the jig 50 comes into contact.

[0046] The inclination angles of the first inclined surfaces 341-344 can be obtained as follows. Here, an example will be described in which the thickness of the protective film 30 is, for example, about 500 μm. Point PA is a location where the thickness of the protective film 30 is, for example, 100 μm. Point PB is a location where the thickness of the protective film 30 is, for example, 400 μm. The inclination angles in the range from point PA to point PB can be set as the inclination angles of the first inclined surfaces 341-344. The inclination angles of the first inclined surfaces 341-344 are obtained based on the inclination angles in such a range because stable inclination angles can be obtained in such a range.

[0047] Next, a membrane strength measuring device 40 used for measuring membrane strength will be described. Fig. 4 is a schematic diagram showing the membrane strength measuring device.

[0048] As shown in FIG. 4, the film strength measuring device 40 includes a lower base 41, an upper base 42, a jig fixing portion 43, an element body holding portion 44, a rod 45, a servo motor 46, a load cell 47, a control device 48, and a display operation portion 49.

[0049] The upper base 42 is provided above the lower base 41. The upper base 42 is supported by a plurality of support columns 421 provided on the lower base 41.

[0050] The jig fixing portion 43 is provided on the lower base 41. The jig fixing portion 43 fixes the jig 50.

[0051] The element body holding portion 44 is provided below the upper base 42. The element body holding portion 44 holds the element body 20 via a holder 55.

[0052] The rod 45 is connected to the element body holding portion 44. The servo motor 46 is provided on the upper base 42. The servo motor 46 raises and lowers the rod 45, thereby raising and lowering the element body holding portion 44.

[0053] The load cell 47 is attached to the rod 45. The load cell 47 detects the load [N] applied to the rod 45. That is, the load cell 47 detects the load applied to the element body 20.

[0054] The control device 48 is responsible for controlling the film strength measuring device 40. The display operation unit 49 can be configured with, for example, a touch panel or the like.

[0055] The jig fixing portion 43 includes a pair of clamping members 431, 432. The pair of clamping members 431, 432 clamp the jig 50 to fix the jig 50. The jig fixing portion 43 further includes a male screw portion 433. The male screw portion 433 screws into a female screw portion (not shown) formed on the clamping member 432. When the male screw portion 433 is rotated, for example, clockwise, the clamping member 432 approaches the clamping member 431. When the male screw portion 433 is rotated, for example, counterclockwise, the clamping member 432 moves away from the clamping member 431.

[0056] The element body holding part 44 includes a pair of clamping members 441, 442. The pair of clamping members 441, 442 clamp the holder 55 to fix the holder 55. The element body holding part 44 further includes male screw parts 443, 444. When the male screw part 443 is rotated, for example, clockwise, the clamping member 441 approaches the clamping member 442. When the male screw part 443 is rotated, for example, counterclockwise, the clamping member 441 moves away from the clamping member 442. When the male screw part 444 is rotated, for example, clockwise, the clamping member 442 moves toward the clamping member 441. When the male screw part 444 is rotated, for example, counterclockwise, the clamping member 442 moves away from the clamping member 441.

[0057] The element body holding part 44 is suspended from the upper base 42 via a rod 45. The element body holding part 44 rises and falls by the driving force of a servo motor 46. As the element body holding part 44 rises and falls, the jig fixing part 43 and the element body holding part 44 approach or move away from each other.

[0058] The control device 48 includes, for example, a calculation unit 481 and a storage unit 482. The calculation unit 481 may be configured by a processor such as a central processing unit (CPU) or a graphics processing unit (GPU), that is, a processing circuitry. At least a part of the control device 48 may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). At least a part of the control device 48 may be configured by an electronic circuit including a discrete device.

[0059] The storage unit 482 may be composed of a volatile memory (not shown) and a non-volatile memory (not shown). The volatile memory may be, for example, a random access memory (RAM). The volatile memory is used as a working memory of the processor, and temporarily stores data and the like required for processing or calculation. The non-volatile memory may be, for example, a read only memory (ROM) or a flash memory. The non-volatile memory is used as a storage memory, and stores programs, tables, maps, and the like. At least a part of the storage unit 482 may be provided in the processor, integrated circuit, and the like described above.

[0060] The control device 48 outputs a control signal to the servo motor 46 to control the lifting and lowering, lifting speed, etc. of the element body holding part 44. A detection signal from the load cell 47 is input to the control device 48. The control device 48 measures the load applied to the holder 55 via the rod 45 and the element body holding part 44 based on the detection signal supplied from the load cell 47.

[0061] The control device 48 outputs a display signal to the display operation unit 49 to display the measurement results and the like on the display screen of the display operation unit 49. The control device 48 also receives an operation signal input by the user via the display operation unit 49.

[0062] The jig (peeling jig) 50 is used when measuring the strength of the protective film 30. The shape of the jig 50 is, for example, substantially cylindrical, as shown in FIG. 4. The jig 50 is provided with a through hole 51 into which the element body 20 is inserted. The central axis of the through hole 51 coincides with the central axis of the jig 50. When measuring the strength of the protective film 30, the rear part of the protective film 30 can be pressed by the jig 50 so that a force in a direction from the rear end to the front end of the element body 20 is applied to the rear part of the protective film 30. The jig 50 can be made of, for example, metal, ceramics, etc. It is preferable that the jig 50 has a relatively low elastic modulus.

[0063] As shown in FIGS. 3A and 3B, the through hole 51 provided in the jig 50 is provided with second inclined surfaces 831 to 834 facing the first inclined surfaces 341 to 344, respectively. That is, the second inclined surfaces 831 to 834 are present in the portion of the jig 50 that contacts the protective film 30. The second inclined surfaces 831 to 834 are inclined with respect to the longitudinal direction of the element body 20. The second inclined surface 831 faces the first inclined surface 341. The second inclined surface 832 faces the first inclined surface 342. The second inclined surface 833 faces the first inclined surface 343. The second inclined surface 834 faces the first inclined surface 344. The inclination angle of the second inclined surfaces 831 to 834 with respect to the longitudinal direction of the element body 20 is a second angle θB. The angle difference (θA-θB) obtained by subtracting the second angle θB from the first angle θA is preferably −10 degrees to +15 degrees.

[0064] The cross-sectional shape of the through hole 51 is, for example, a rectangle. That is, the cross-sectional shape of the through hole 51 in a direction perpendicular to the longitudinal direction of the through hole 51 is, for example, a rectangle. The cross-sectional dimensions of the through hole 51 are set to a dimension that allows the element body 20 to be inserted. Moreover, the cross-sectional dimensions of the through hole 51 are set to a dimension that does not allow the protective film 30 to be inserted.

[0065] Fig. 5 is a diagram showing the relationship between the size of a through hole and the size of a sensor element. Fig. 5 shows the sensor element 10 with the element body 20 inserted into the through hole 51 as viewed from behind the sensor element 10.

[0066] 5, the diameter HA of the through hole 51 in the up-down direction is larger than the outer diameter EA of the element body 20 in the up-down direction. Moreover, the diameter HB of the through hole 51 in the left-right direction is larger than the outer diameter EB of the element body 20 in the left-right direction. Moreover, the diameter HA of the through hole 51 in the up-down direction is smaller than the outer diameter FA of the protective film 30 in the up-down direction. Moreover, the diameter HB of the through hole 51 in the left-right direction is smaller than the outer diameter FB of the protective film 30 in the left-right direction.

[0067] When the central axis of the element body 20 and the central axis of the through hole 51 are aligned, the dimension of the gap between the element body 20 and the through hole 51 is defined as LA. The thickness of the protective film 30 is defined as LB. The ratio of the thickness LB to the dimension LA is preferably 0.3 or more and 0.7 or less.

[0068] The shape of the holder 55 is, for example, a substantially rectangular parallelepiped, as shown in Fig. 4. The holder 55 is provided with a through hole 56. The element body 20 can be inserted into the through hole 56. The cross-sectional shape of the through hole 56 is, for example, rectangular. That is, the cross-sectional shape of the through hole 56 in a direction perpendicular to the longitudinal direction of the through hole 56 is, for example, rectangular. When the element body 20 is inserted into the through hole 56, the central axis of the holder 55 coincides with the central axis of the element body 20.

[0069] As shown in FIG. 3A and FIG. 3B, the element body 20 is held by a holder 55 behind the jig 50. The holder 55 is provided with an elastic body 57. The elastic body 57 is provided at a portion of the holder 55 that contacts the element body 20. In this embodiment, an example in which the entire holder 55 is made of the elastic body 57 will be described, but the present invention is not limited to this. The elastic body 57 may be provided only at a portion of the holder 55 that contacts the element body 20. For example, a rubber containing nitrile butadiene rubber (NBR) as a main component may be used as the elastic body 57. For example, a rubber containing chloroprene rubber (CR) as a main component may be used as the elastic body 57. The hardness value of the elastic body 57 measured with a type A durometer in accordance with JIS K6253-3:2012 is preferably 60 or more and 1300 or less.

[0070] Next, the film strength measuring method according to this embodiment will be described.

[0071] First, as shown in Figures 3A and 3B, a jig 50 is attached to the sensor element 10. Specifically, the sensor element 10 and the jig 50 are moved relative to each other to insert a portion of the element body 20 that is not covered by the protective film 30 into the through hole 51. Then, the rear end of the element body 20 is caused to protrude from the through hole 51. In this way, at least the rear end of the element body 20 is inserted into the through hole 51.

[0072] 3A and 3B, a holder 55 is attached to the element body 20. Specifically, a portion of the element body 20 that is not covered by the protective film 30 is inserted into a through hole 56 provided in the holder 55. In this way, the element body 20 is held by the holder 55 behind the jig 50.

[0073] Next, as shown in FIG. 4, the sensor element 10 to which the jig 50 and the holder 55 are attached is attached to the film strength measuring device 40. Specifically, the jig 50 is fixed by clamping it with the clamping members 431 and 432 provided in the jig fixing portion 43. The jig 50 is clamped by the clamping members 431 and 432 in the thickness direction of the element body 20. The holder 55 is also held by clamping it with the clamping members 441 and 442 provided in the element body holding portion 44. The holder 55 is clamped by the clamping members 441 and 442 in the thickness direction of the element body 20. Thereafter, a zero adjustment is performed so that the value of the load detected in this state becomes zero.

[0074] Next, as shown in FIG. 6A, the sensor element 10 and the jig 50 are moved relative to each other while the element body 20 is held by the holder 55. FIGS. 6A and 6B are diagrams showing the state of moving the sensor element and the jig relative to each other. When moving the sensor element 10 and the jig 50 relative to each other, the sensor element 10 and the jig 50 are moved relative to each other in the longitudinal direction of the element body 20. Specifically, the sensor element 10 and the jig 50 are moved relative to each other as follows. That is, first, an instruction to start measurement is given. Such an instruction can be given by a user via, for example, the display operation unit 49. When an instruction to start measurement is given, the control device 48 controls the servo motor 46 to raise the element body holding unit 44 at a predetermined speed. By raising the element body holding unit 44, the sensor element 10 and the jig 50 move relative to each other. It is preferable to move the sensor element 10 and the jig 50 relative to each other at a speed of 0.8 mm / sec or more and 1.2 mm / sec or less, but this is not limited thereto. As the element body holding portion 44 is raised, the rear portion of the protective film 30 approaches the jig 50 .

[0075] As the element body holding portion 44 is raised, the rear portion of the protective film 30 comes into contact with the jig 50, as shown in Fig. 6B. Then, the rear portion of the protective film 30 is pressed by the jig 50 so that a force in the direction from the rear end portion to the front end portion of the element body 20 is applied to the rear portion of the protective film 30.

[0076] When the state in which the rear part of the protective film 30 is pressed by the jig 50 continues, the protective film 30 is peeled off from the element body 20. Thereafter, when the protective film 30 is peeled off from the element body 20, an end instruction is given. The end instruction may be given, for example, by a user. When the end instruction is given, the control device 48 stops the servo motor 46. It should be noted that the control device 48 may automatically stop the servo motor 46 without being based on the end instruction from the user. For example, when the amount of lift of the element body holding part 44 reaches a predetermined amount, the servo motor 46 may be automatically stopped. The control device 48 measures the strength of the protective film 30 based on the magnitude of the force (load) when the protective film 30 is peeled off from the element body 20. Specifically, the control device 48 acquires the load applied to the element body 20 (load applied in the longitudinal direction of the element body 20) in chronological order. The load can be acquired based on a detection signal supplied from the load cell 47. The control device 48 displays the change over time of the load on the display screen of the display operation part 49. Based on the load thus obtained, the film strength [N] of the protective film 30 is measured. In other words, based on the load thus obtained, the pull-out strength of the protective film 30 is measured. After the rear part of the protective film 30 abuts against the jig 50, the load detected by the load cell 47 increases with time. Then, when peeling of the protective film 30 occurs, the load detected by the load cell 47 decreases. Based on the peak value of the load detected by the load cell 47, the strength of the protective film 30 can be determined.

[0077] Fig. 7 is a graph showing the relationship between the angle difference and the film strength. The horizontal axis in Fig. 7 shows the angle difference (θA-θB) obtained by subtracting the second angle θB from the first angle θA. The vertical axis in Fig. 7 shows the film strength (pull-out strength). That is, the vertical axis in Fig. 7 shows the load when the protective film 30 peeled off. Fig. 7 shows measurements performed on a protective film 30 with normal strength.

[0078] As shown in FIG. 7, when the angle difference (θA-θB) is relatively large, the film strength is significantly reduced. The reason why the film strength is reduced when the angle difference (θA-θB) is relatively large is that the protective film 30 is destroyed by the jig 50 when the angle difference (θA-θB) is relatively large. When the protective film 30 is destroyed by the jig 50, the film strength of the protective film 30 cannot be measured properly. When a protective film 30 having normal strength is measured, it is preferable that a film strength of a predetermined value or more is observed. When a protective film 30 having normal strength is measured, a film strength of a predetermined value or more is observed when the angle difference (θA-θB) is -10 degrees or more and +15 degrees or less. Therefore, it is preferable that the angle difference (θA-θB) is -10 degrees or more and +15 degrees or less.

[0079] Thus, in this embodiment, the second inclined surfaces 831-834 inclined with respect to the longitudinal direction of the element body 20 are present at the portion of the jig 50 that abuts against the protective film 30. Therefore, according to this embodiment, even though the first inclined surfaces 341-344 are present at the portion of the protective film 30 that abuts against the jig 50, the rear portion of the protective film 30 is pressed satisfactorily by the jig 50. Therefore, according to this embodiment, the strength of the protective film 30 can be measured satisfactorily.

[0080] The present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

[0081] For example, in the above embodiment, the jig 50 is provided with four second inclined surfaces 831-834 that respectively abut on the four first inclined surfaces 341-344, but the present invention is not limited to this. When the jig 50 abuts on the first inclined surfaces 341, 342 but does not abut on the first inclined surfaces 343, 344, the second inclined surfaces 833, 834 do not have to be provided on the jig 50.

[0082] In the above embodiment, the jig 50 is provided with the four second inclined surfaces 831-834 that respectively abut against the four first inclined surfaces 341-344. However, the present invention is not limited to this. When the jig 50 abuts against the first inclined surface 341 but does not abut against the first inclined surfaces 342-344, the second inclined surfaces 832-834 do not have to be provided on the jig 50.

[0083] The invention that can be understood from the above-described embodiments will be described below.

[0084] The film strength measuring method is a film strength measuring method for measuring the strength of a protective film (30) covering a front end, which is one end in the longitudinal direction of an element body (20) constituting a sensor element (10), and includes the steps of pressing the rear end of the protective film with a jig (50) so that a force is applied to the rear end of the protective film in a direction from the rear end, which is the other end in the longitudinal direction of the element body, toward the front end, and measuring the strength of the protective film based on the magnitude of the force when the protective film is peeled off from the element body by the jig, wherein at a portion of the protective film with which the jig abuts, a first inclined surface (341-344) inclined with respect to the longitudinal direction is present due to the thickness of the protective film decreasing toward the rear end of the protective film, and at a portion of the jig with which the protective film abuts, a second inclined surface (831-834) facing the first inclined surface and inclined with respect to the longitudinal direction is present. According to this configuration, the second inclined surface inclined with respect to the longitudinal direction of the element body is present at the portion of the jig that contacts the protective film. Therefore, according to this configuration, even though the first inclined surface is present at the portion of the protective film that contacts the jig, the rear portion of the protective film is pressed well by the jig. Therefore, according to this configuration, the strength of the protective film can be measured well.

[0085] The inclination angle of the first inclined surface with respect to the longitudinal direction may be a first angle (θA), the inclination angle of the second inclined surface with respect to the longitudinal direction may be a second angle (θB), and an angle difference (θA-θB) obtained by subtracting the second angle from the first angle may be -10 degrees to +15 degrees. With this configuration, the protective film is less likely to be damaged by a jig, so that the strength of the protective film can be measured more satisfactorily.

[0086] The protective film includes at least a first portion (301) covering a first main surface (201) of the element body, and a second portion (302) covering a second main surface (202) located opposite to the first main surface, and the first inclined surfaces (343, 344) are present at a portion of the first portion with which the jig abuts and at a portion of the second portion with which the jig abuts, respectively, and the jig has second inclined surfaces facing the multiple first inclined surfaces, and is larger than an outer diameter (EA, EB) of the element body and smaller than an outer diameter (FA, FB) of the protective film. ) is formed in the protective film, and the method further includes, before the step of pressing the rear portion of the protective film with the jig, the steps of inserting at least the rear end of the element body into the through hole, holding the element body with a holder (55) behind the jig, and moving the sensor element and the jig relative to each other while the element body is held by the holder, and in the step of pressing the rear portion of the protective film with the jig, the rear portion of the first portion and the rear portion of the second portion may be pressed by the jig.

[0087] When the central axis of the element body and the central axis of the through hole are aligned, the dimension of the gap between the element body and the through hole is LA, and the thickness of the protective film is LB, the ratio of LB to LA may be 0.3 or more and 0.7 or less.

[0088] The portion of the holder that comes into contact with the element body may be provided with an elastic body (57) having a hardness value of 60 or more and 1300 or less, measured with a type A durometer in accordance with JIS K6253-3:2012.

[0089] In the step of moving the sensor element and the jig relatively, the sensor element and the jig may be moved relatively at a speed of 0.8 mm / sec or more and 1.2 mm / sec or less.

[0090] The protective film may include an inner protective layer (321) and an outer protective layer (322) located outside the inner protective layer, the porosity of the inner protective layer being 40% or more and 60% or less, the thickness of the inner protective layer being 170 μm or more and 900 μm or less, the porosity of the outer protective layer being 15% or more and 50% or less, and the thickness of the outer protective layer being 30 μm or more and 300 μm or less. [Explanation of symbols]

[0091] 10: Sensor element 12: Laminate 20: Element body 30: Protective film 40: Membrane strength measuring device 41: Lower base 42: Upper base 43: Jig fixing part 44: Element body holding part 45: Rod 46: Servo motor 47: Load cell 48: Control device 49: Display operation unit 50: Jig 51, 56: Through hole 55: Holder 57: Elastic body 60: First substrate layer 62: Second substrate layer 64, 66, 70: Solid electrolyte layer 68: Spacer layer 79: Measurement gas flow path 80: Gas inlet 82: First diffusion-controlling portion 84: Buffer space 86: second diffusion-controlling portion; 88: first internal cavity 90: third diffusion-controlling portion 92: second internal cavity 94: 4th diffusion-controlling section 96: 3rd internal cavity 98: Reference gas introduction space 100: Air introduction layer 102: Reference electrode 112: Pump electrode 114: Outer pump electrode 126: Auxiliary pump electrode 134: Measuring electrode 160: Heater section 162: Connector electrode 164: Heater 166: Through hole 168: Heater insulation layer 170: Pressure relief hole 172: Lead wire 182: Reference gas chamber 201: First main surface 202: Second main surface 203: Right side surface 204: Left side 205: Rear end side 206: Front end surface 301: First part 302: 2nd part 303: 3rd part 304: 4th part 305: 5th part 321: Inner protective layer 322: Outer protective layer 341~344: 1st slope 421: Post 431, 432, 441, 442: Holding member 433, 443, 444: Male thread part 481: Operation part 482: Storage section 831~834: Second slope EA, EB, FA, FB: Outer diameter HA, HB: Diameter LA: Dimension LB: Film thickness θA: 1st angle θB: 2nd angle

Claims

1. A film strength measuring method for measuring the strength of a protective film covering a front end portion, which is one end portion in a longitudinal direction of an element body constituting a sensor element, comprising: pressing the rear portion of the protective film with a jig so that a force is applied to the rear portion of the protective film in a direction from a rear end, which is the other end in the longitudinal direction of the element body, toward the front end; measuring a strength of the protective film based on a magnitude of a force when the protective film is peeled off from the element body by the jig; having a first inclined surface inclined with respect to the longitudinal direction is present at a portion of the protective film with which the jig abuts, the thickness of the protective film decreasing toward a rear end of the protective film; A film strength measuring method in which a portion of the jig that abuts the protective film is provided with a second inclined surface that faces the first inclined surface and slopes along the first inclined surface, due to the thickness of the jig decreasing as it moves away from the front end of the jig.

2. The film strength measuring method according to claim 1, an inclination angle of the first inclined surface with respect to the longitudinal direction is a first angle, an inclination angle of the second inclined surface with respect to the longitudinal direction is a second angle; a difference in angle obtained by subtracting the second angle from the first angle is in the range of −10 degrees to +15 degrees.

3. 3. The method for measuring film strength according to claim 1, the protective film includes at least a first portion covering a first main surface of the element body and a second portion covering a second main surface located opposite to the first main surface, The first inclined surface is present at a portion of the first portion against which the jig abuts and at a portion of the second portion against which the jig abuts, the jig includes the second inclined surfaces facing the first inclined surfaces, and a through hole is formed in the jig, the through hole being larger than an outer diameter of the element body and smaller than an outer diameter of the protective film; Before the step of pressing the rear portion of the protective film with the jig, inserting at least the rear end portion of the element body into the through hole; holding the element body with a holder behind the jig; a step of moving the sensor element and the jig relative to each other while the element body is held by the holder; Further comprising: In the step of pressing the rear portion of the protective film with the jig, the rear portion of the first portion and the rear portion of the second portion are pressed with the jig.

4. The film strength measuring method according to claim 3, The dimension of the gap generated between the element body and the through hole in a state where the central axis of the element body and the central axis of the through hole are aligned is defined as LA, If the thickness of the protective film is L, The ratio of LB to LA is 0.3 or more and 0.7 or less, the method for measuring membrane strength.

5. The film strength measuring method according to claim 3 or 4, A film strength measuring method, wherein a portion of the holder that contacts the element body is provided with an elastic body having a hardness value of 60 or more and 1,300 or less as measured with a type A durometer in accordance with JIS K6253-3:2012.

6. The film strength measuring method according to any one of claims 3 to 5, In the step of moving the sensor element and the jig relatively, the sensor element and the jig are moved relatively at a speed of 0.8 mm / sec or more and 1.2 mm / sec or less.

7. The film strength measuring method according to any one of claims 1 to 6, The protective film includes an inner protective layer and an outer protective layer located outside the inner protective layer, The porosity of the inner protective layer is 40% or more and 60% or less, The thickness of the inner protective layer is 170 μm or more and 900 μm or less, The porosity of the outer protective layer is 15% or more and 50% or less, The method for measuring film strength, wherein the thickness of the outer protective layer is 30 μm or more and 300 μm or less.

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