JP5416530B2 - Gas sensor - Google Patents

Description

  The present invention relates to gas sensors used in a wide range of applications such as detection of various gas leaks and toxic gases, monitoring of exhaust gas and air pollution, monitoring of various processes, etc., particularly carbon monoxide generated during incomplete combustion in a combustion apparatus. The present invention relates to a gas sensor that accurately detects leakage of (CO) gas or hydrogen gas in a fuel cell vehicle (FCV).

  Conventionally, as a sensor for detecting a combustible gas such as hydrogen gas, methane gas, or carbon monoxide gas, there are a catalytic combustion type gas sensor, a semiconductor type gas sensor, and the like. Each of these gas sensors incorporates a heat source that is used to detect flammable gases.

  For example, as described in Patent Document 1, the catalytic combustion type gas sensor has a gas sensitive element (detecting element) including a heater coil provided with a combustion catalyst as a heat source, and is generated on the combustion catalyst. The presence of the combustible gas is detected by outputting the change in resistance value of the heater coil due to the contact combustion heat of the combustible gas as a voltage change.

  In addition, the semiconductor gas sensor has a gas sensitive element composed of a heater coil provided with a semiconductor layer as a heat source, and changes in the electrical conductivity of the semiconductor layer caused by the adsorption phenomenon of the combustible gas in this semiconductor layer are changed in voltage. Is output to detect the presence of combustible gas.

  These existing gas sensors have a heat source for detecting flammable gas as described above. In order to stabilize the thermal equilibrium performance of the gas sensor and to ensure the explosion-proof performance against the flammable gas, a metal mesh, a metal firing is provided. It is equipped with a gas permeable cap composed of a knot or ceramics.

  Furthermore, in order to compensate for the influence of changes in ambient temperature, a compensation element is connected in series with the sensing element, and a Wheatstone bridge circuit is configured by connecting in parallel with a series circuit in which two resistors are connected in series. Patent Document 1 also discloses a gas detection device in which a DC voltage is applied between both ends of the parallel circuit to detect a voltage between a connection point between the detection element and the compensation element and a connection point between the two resistors. Has been. As a compensation element in this case, an element in which a heater coil having the same electrical characteristics as that of the sensing element is embedded in a heat conductive layer that is not covered or supported by an oxidation catalyst is used.

On the other hand, these existing gas sensors are provided with a synthetic resin mount base having no gas permeability. The mount base supports the detection element and the compensation element in a state of passing through a pair of electrode pins electrically connected to and supported by both terminals of the detection element and the compensation element. Hold it inside.
Thus, when the sensing element and the compensating element are installed in the same housing, a metal or synthetic resin heat shielding plate is provided between the two elements in order to prevent thermal interference between the two elements. .

  However, the gas permeable cap in such a gas sensor has a function of protecting the sensing element against environmental factors. On the other hand, the gas permeable cap restricts the gas permeable property, thereby causing a deterioration in the response performance of the sensor. In addition, the existing mount base does not contribute at all to the detection target gas permeating into the sensor, and therefore does not contribute to the response performance of the sensor. Furthermore, although the heat shielding plate in the contact combustion type gas sensor is provided for the purpose of heat insulation between the detection element and the compensation element, on the other hand, the atmosphere environment of both elements inside the sensor is cut off. It is not necessarily preferable for the stability of the output voltage with respect to the temperature and humidity characteristics.

  Therefore, as described in, for example, Patent Document 2, in the gas sensor including the cap, the mount base, and the heat shielding plate as described above, the gas to be detected is configured by ceramics, preferably porous ceramics. Has been proposed that allows gas to flow into the sensor from all directions so that the gas concentration inside the gas sensor matches that of the surrounding environment at high speed, thereby improving the response performance of the gas sensor output.

  Patent Document 3 discloses a catalytic combustion type gas sensor having improved strength against impact caused by dropping or the like. In this contact combustion type gas sensor, a detection element and a comparison element are integrally attached to a base with a heat shield plate interposed therebetween, and the detection element pin and the comparison element pin are flexible and face the heat shield plate. The respective positions are arranged so as not to overlap each other in the direction perpendicular to the plane of the heat shielding plate, and the intermediate portion of each pin is bent in the same direction perpendicular to the plane of the heat shielding plate, The tips of the pins are joined to the substrate in a row. By adopting such a configuration, the pin portion bends when subjected to an impact such as a drop, thereby reducing the impact and reducing sensor failure due to deterioration of the sensing element or disconnection of the lead portion. It is.

JP-A-3-162658 JP 2006-126160 A JP 2006-177975 A

  However, in the conventional gas sensor disclosed in Patent Document 1, as described above, the electrode pin of the gas sensitive element, or each electrode pin of the compensation element is also supported through the mount base, and each base end of the gas sensor is mounted on the mount. It protrudes from the back of the base vertically by a certain length. Therefore, since each electrode pin is close and the material is difficult to solder, such as Hastelloy, which is generally a kind of stainless steel, the workability of wiring between each electrode pin and the detection circuit is poor, and the equipment The degree of freedom in mounting is low, and extra space may be required.

  In addition, the conventional gas sensor disclosed in Patent Document 3 is provided with a long pin to be connected to the external substrate, and a part of the pin is bent to obtain a buffering action, thereby improving impact resistance. However, even if the impact on the sensor itself is reduced, if tensile stress or torsional stress is applied to the pin, the impact will be directly applied to the soldered part, which may cause damage to the connection part. There is a high possibility of problems. In addition, since the pin also holds the detection element and the comparison element inside the sensor, there is a risk that an applied impact may reach the holding portion of the detection element and the comparison element, which may cause fatal damage to the sensor. .

  Therefore, the present invention has been made to solve such problems, increasing the degree of freedom when mounting on equipment, protecting the connection terminal portion with the outside, damage due to the force applied to the connection terminal portion, etc. It is an object of the present invention to provide a gas sensor that can prevent the above.

  The gas sensor of the present invention includes at least a gas sensitive element, a plurality of electrode pins that are electrically connected to the gas sensitive element at one end portion thereof to support the gas sensitive element, and each of the plurality of electrode pins. A mount base made of an insulating material penetrating from one surface to the other surface and supported, and a gas permeability fixed to the mount base so as to cover the region on the one surface side including the gas sensitive element of the mount base A cover member, an out lead connected to a portion of the plurality of electrode pins protruding from the other surface of the mount base, and the electrode pins on the side of the mount base from which the electrode pins protrude. And a spacer that supports each of the out leads, and a pressing member that is disposed so as to cover substantially the entire surface of the spacer that supports each of the out leads, Wherein even and the pressing member locking pieces for locking by pressing the member to the spacer side, to become a.

  The electrode pin and the connection portion between the electrode pin and the out lead are covered with a spacer and a pressing member, and the spacer and the pressing member are pressed and held by the pressing member locking piece, so that a structure that is strong against external stress is provided. can get.

  Further, a part of the outer peripheral portion of the pressing member is formed in an inclined surface portion that gradually increases in the outer peripheral direction, and the tip portion of the pressing member locking piece is brought into contact with the inclined surface portion. Can be configured.

  Moreover, the edge part of the inclined surface part of the said pressing member can be set as the structure by which the chamfering process was performed.

  Moreover, the front-end | tip part of the said pressing member locking piece can form the inclined part cut | disconnected by the angle larger than the inclined surface part of the said pressing member.

  Further, the pressing member locking piece may be made of a metal having a spring property.

  According to the present invention, the connection terminal portion with the outside can be configured to be strong against external stress, and damage to the out lead and the connection portion between the out lead and the electrode pin due to the external stress can be suppressed. A gas sensor having a possible structure is obtained.

In the gas sensor of this invention, (a) is the perspective view which looked at the gas detection part side upward, (b) is the perspective view which looked at (a) upside down. Side surface sectional drawing of the gas sensor of this invention. The disassembled perspective view which looked at the out-lead side of the gas sensor of this invention facing up. The perspective view which looked at the out-lead side upward in the other example which shows the gas sensor of this invention. FIG. 5 is a side view of FIG. 4 showing another example of the gas sensor of the present invention.

The best mode for carrying out the present invention will be specifically described below with reference to the drawings.
First, the external appearance of the gas sensor according to the present invention will be described with reference to FIG. This gas sensor is an example of a contact combustion type gas sensor. FIG. 1A is a perspective view of the gas sensor as viewed from the side facing the gas detection portion, and FIG. 1B is a perspective view of the gas sensor viewed upside down. FIG.

In this gas sensor, each member is held by a holder 1 including a holder substrate 11 serving as a mounting plate and a spring-like holder 12 integrally fixed to the back side thereof.
The holder substrate 11 is formed with an annular projecting portion 11b having a circular opening 11a at the center, and mounting holes 11c are provided on both sides in the longitudinal direction.

  A disc-shaped mount base, which will be described later, is fitted and fixedly held in an annular projecting portion 11b of the holder substrate 11, and the cap 3 fixed to one surface of the mount base is shown in FIG. ) Protrudes from the circular opening 11a. The cap 3 has gas permeability, and in this example, is formed in a dome shape with porous ceramics.

  As will be described in detail later, in the cap 3, a sensing element and a compensation element, which are gas sensitive elements, are supported by a pair of electrode pins passing through the pin stays, with both terminals connected to each other. And is fixedly held on the mount base via and arranged opposite to each other.

  On the other hand, the electrode pins (four) protrude from the back side of the holder 1 and are inserted through the spacers 4 so as to be parallel to the back side of the holder 1 on the upper surface side of FIG. 1B (the other surface of the mount base). Are connected to stainless-made out leads 5a, 5b and 5c extending in a direction parallel to the same. In this example, of the four electrode pins, two electrode pins connected to one terminal of each of the detection element and the compensation element are commonly connected to one out lead 5a, and the remaining two electrode pins are The two out leads 5b and 5c are individually connected. (See FIG. 3 below.)

  On the back side of the spring-like holder 12 provided on the side from which each electrode pin of the holder 1 protrudes, a disk-like spacer 4 that penetrates each electrode pin and guides and supports each outlead 5a, 5b, 5c. And a disc-like pressing member 6 that covers substantially the entire surface of the spacer 4 that supports each outlead, and is positioned and held by a spring holder 12.

  Therefore, the spring-like holder 12 has a pair of spacer holding pieces 12a (only one of which is shown in FIG. 1 (b)) that holds the outer peripheral surface of the spacer 4 facing each other, and the pressing member 6 with each other. A pair of pressing member locking pieces 12b that are pressed and locked to the spacer side at opposite positions are integrally formed of a metal plate having a spring property. The spring holder 12 is integrated by welding a peripheral fan-shaped portion 12 c to the holder substrate 11.

After arranged to overlap the pressing member 6 on the spacer 4, the locking piece portion 12b ₁ formed on both sides of the front end portion of the pressing member locking pieces 12b of the spring property holder 12, in FIGS 1 (b) When bent at a substantially right angle in the direction indicated by the arrow, it abuts against the back surface of the pressing member 6 and presses the pressing member 6 against the spacer 4 by the spring force strengthened by the curvature of the rising portion of each pressing member locking piece 12b. And hold firmly. The spacer holding pieces 12a and the pressing member locking pieces 12b of the spring holder 12 are not limited to a pair, but may be provided in plural, or may be provided at three or more locations at equal angular intervals. Both the spacer 4 and the pressing member 6 may be formed of ceramics.

Next, the internal structure of this gas sensor will be described with reference to FIG.
FIG. 2 is a side cross-sectional view of the gas sensor shown in FIGS. The holder substrate 11 is a member having a somewhat elongated baseball shape formed by pressing a stainless steel plate, and as described above, the annular protrusion 11b having a circular opening 11a at the center is formed by drawing. Has been.

  The mount base 2 has a disk shape, a thin heat shielding plate fitting slot 21 is formed along the diameter line, and the heat shielding plate 9 is erected. A pair of pin stay fitting slots 22 and 23 are formed on both sides of the slot 21 and the heat shield plate 9, respectively. In the slots 22 and 23, pin stays 7 and 8 are fitted and arranged.

  A pair of electrode pins 7 a (the other electrode pin 7 a is not shown in FIG. 2 is not shown) is inserted through the pin stay 7. The electrode pin 7a is electrically connected to a sensing element which is a gas sensitive element (not shown) to constitute a sensing element unit.

  The sensing element, which is the gas sensitive element, has a heater coil made of a platinum alloy wire embedded in a heat conductive layer that covers or carries an oxidation catalyst that burns the gas to be detected by contact. Are connected to the electrode pin 7a.

  A pair of electrode pins 8 a (the other electrode pin 8 a is not shown in FIG. 2 because it is a cross-sectional view) are inserted into the pin stay 8. A compensation element (not shown) is electrically connected to the electrode pin 8a to constitute a compensation element unit.

  The compensation element is an element provided to compensate for the influence of changes in ambient temperature, and a heater coil having the same electrical characteristics as the heater coil of the detection element is embedded in a heat conductive layer that does not have an oxidation catalyst. The both ends of the heater coil are connected to the electrode pin 8a.

  The mount base 2, the detection element unit pin stay 7, the compensation element unit pin stay 8, and the heat shield plate 9 are all made of a heat-resistant insulating material, preferably ceramics. Depending on the application, the mount base 2 and the heat shielding plate 9 may be formed of porous ceramics. The electrode pins 7a and 8a are made of a conductive material having high heat resistance and corrosion resistance, for example, Hastelloy which is a kind of stainless steel.

  In FIG. 2, a dome-shaped cap 3 is covered on the upper surface side of the mount base 2 so as to cover the detection elements and compensation elements connected to the electrode pins 7a and 8a, respectively. The cap 3 is configured to have gas permeability and is fixed by bonding with a glass adhesive or the like.

  A spacer 4 for inserting the electrode pins 7a and 8a is disposed on the lower surface side of the mount base 2, and the outer peripheral surfaces of the electrode pins 7a and 8a are covered and protected by the spacer 4. Further, the pressing member 6 is disposed so as to cover the surface of the spacer 4, and the out leads 5 a, 5 b, 5 c not shown in FIG. 2 are also covered and protected.

FIG. 3 is an exploded perspective view of the gas sensor according to the present invention when the out lead side is viewed upward.
The spacer 4 is arranged so that the electrode pins 7 a and 8 a are inserted through the through holes 4 a provided in the spacer 4. Here, the thickness of the spacer 4 to the bottom surface of the groove 4b (depth of the through hole 4a) is set to be slightly lower than the length of the electrode pins 7a, 8a protruding outward, and the tips of the electrode pins 7a, 8a The part is arranged in a state of slightly protruding from the bottom surface of the groove 4 b provided in the spacer 4. Out leads 5a, 5b and 5c are connected to the tip portions of the electrode pins 7a and 8a by means such as welding. The out leads 5 a, 5 b, and 5 c are configured to extend in a direction parallel to the surface of the spacer 4. The out leads 5 a, 5 b, 5 c are arranged and supported in the groove 4 b formed on the surface of the spacer 4. Although not shown, the groove 4b in which the out leads 5a, 5b, and 5c are disposed is filled with an insulating adhesive or the like and fixed.

  As shown in FIG. 3, the pressing member 6 is closely attached so as to cover substantially the entire surface of the spacer 4 on the side supporting the out leads 5 a, 5 b, 5 c, and the out leads 5 a, 5 b, 5c is sandwiched and held.

  According to such a configuration, the out leads 5a, 5b, and 5c are firmly held, and at the same time, the electrode pins 7a and 8a and the out leads 5a, 5b, and 5c are not exposed to the outside. The structure is protected against various stresses such as twisting and twisting, and the impact is eliminated, and the damage to each lead and the connection with the electrode pin is eliminated, and a highly reliable gas sensor can be obtained.

  FIG. 4 is a view showing another example of the gas sensor of the present invention, and is a perspective view seen from the out-lead side. FIG. 5 is a side view of FIG. In this structure, the convex part 10a is formed in the outer surface side of the pressing member 10, and the surface is uneven | corrugated and the surface area is increased. The means for increasing the surface area is not limited to the formation of the convex portion 10a, and a groove may be formed on the surface of the pressing member 10.

  Gas sensors are installed in various boiler devices and detect gas leaks and toxic gases, monitor exhaust gases and air pollution, monitor various processes, etc., and can be used in high-temperature environments. In addition, a high heat-resistant structure is also required for a portion serving as a connection terminal to the outside. However, with the above-described configuration, an area in contact with outside air is increased, so that a heat dissipation effect is improved. Therefore, a gas sensor excellent in heat dissipation performance can be obtained. In addition, the unevenness | corrugation and groove | channel provided in the holding | suppressing member 10 can adjust the heat dissipation by increasing / decreasing the surface area which touches external air by changing the height and groove depth. It is also possible to adjust the heat dissipation by utilizing the difference in the thermal conductivity characteristics of the material of the member (difference in material performance). Of course, the heat dissipation can also be adjusted by the combination of the above various methods. It is.

In addition, in the gas sensor shown in FIGS. 4 and 5, an inclined surface portion 10b is formed on a part of the outer peripheral portion of the pressing member 10, and the tip end portion (the locking piece) of the pressing member locking piece 12b is formed on the inclined surface portion 10b. The tip of the portion 12b ₁ is in contact. As shown in FIG. 5, the inclined surface portion 10 b is an inclined surface portion 10 b that gradually increases in the outer circumferential direction of the pressing member 10. With such a configuration, the engaging piece portion 12b ₁ the pressing member 10 of the pressing member locking pieces 12b can be configured unlikely to deviate outwardly, the holding force of the pressing member 10 and the spacer 4 is firmly maintained It becomes like this.

Further, the end portion (edge portion) of the inclined surface portion 10b of the pressing member 10 can be chamfered. With such a configuration, after the pressing member 10 is placed over the spacer 4, the locking piece portions 12 b ₁ on both sides of the distal end of each pressing member locking piece 12 b of the spring-like holder 12 are moved to the pressing member 10. liable to work to bend easily ride up the form toward the center of the back, can be as engaging piece portion 12b ₁ is brought into contact with the inclined surface portion 10b of the pressing member 10. Therefore, the holding force can be maintained by pressing the pressing member 10 against the spacer 4 by the spring force of each pressing member locking piece 12b.

Further, the engaging piece portion 12b ₁ is the tip portion of the pressing member locking pieces 12b, it is possible to form an inclined portion 12d which is cut by the inclined surface portion 10b is larger than the angle of the pressing member 10. For example, if you set the inclination angle of 5 degrees of the inclined surface portion 10b, the inclination angle of the inclined portion 12d of the locking piece portion 12b ₁ may be set to approximately 8 degrees. Tip of the engaging piece portion 12b ₁ in such a configuration is securely abuts on the inclined surface portion 10b of the said presser member 10. Therefore, out the pressing member locking piece 12b by even force is applied toward the outside from the center of the pressing member locking piece 12b or the pressing member 10 in the locking piece portion 12b ₁ is inclined surface 10b forming a role as a stopper This prevents the problem that

DESCRIPTION OF SYMBOLS 1 Holder 2 Mount base 3 Cap 4 Spacer 4a Through-hole 4b Groove part 5a Out lead 5b Out lead 5c Out lead 6 Holding member 7 Pin stay 7a Electrode pin 8 Pin stay 8a Electrode pin 9 Heat shielding board 10 Holding member 10a Convex part 10b Inclined surface part 11 Holder substrate 11a Opening 11b Protruding portion 11c Mounting hole 12 Spring holder 12a Spacer holding piece 12b Holding member locking piece 12b ₁ Locking piece portion 12c Fan-shaped portion 12d Inclined portion

Claims (5)

at least,
A gas sensitive element;
A plurality of electrode pins that are electrically connected to the gas sensitive element at one end to support the gas sensitive element;
A mount base made of an insulating material that supports the plurality of electrode pins by penetrating from one surface to the other surface;
A gas permeable cover member fixed to the mount base so as to cover the area on the one surface side including the gas sensitive element of the mount base;
An out lead connected to a portion of the plurality of electrode pins protruding from the other surface of the mount base;
A spacer that is provided on the side of the mount base on which the electrode pins protrude, passes through the electrode pins, and supports the out leads;
A pressing member disposed so as to cover substantially the entire surface of the spacer that supports each outlead;
A gas sensor comprising: a pressing member locking piece that presses and locks the pressing member toward the spacer.   A part of the outer peripheral part of the pressing member is formed with an inclined surface part that gradually increases in the outer peripheral direction, and the tip part of the pressing member locking piece is in contact with the inclined surface part. The gas sensor according to claim 1, wherein   The gas sensor according to claim 2, wherein an end portion of the inclined surface portion of the pressing member is chamfered.   4. The gas sensor according to claim 2, wherein a tip portion of the pressing member locking piece is formed with an inclined portion cut at an angle larger than an inclined surface portion of the pressing member. The gas sensor according to claim 1, wherein the pressing member locking piece is made of a metal having a spring property.

Images