JP5155229B2 - 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, the detection element and the comparison element are integrally attached to the base with the heat shield plate interposed therebetween, and the detection element pin and the comparison element pin have flexibility and are opposed to the heat shield plate. Are arranged so as not to overlap each other in a direction perpendicular to the plane of the heat shield plate, and an intermediate portion of each pin is bent in the same direction perpendicular to the plane of the heat shield plate, The tip of each pin is 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, the electrode pins are close to each other, and the material is generally difficult to solder, such as Hastelloy, which is a kind of stainless steel. Therefore, the workability of the wiring between each electrode pin and the detection circuit is poor. was there. In addition, the degree of freedom in mounting on equipment is low, and extra space may be required.

  In the conventional gas sensor disclosed in Patent Document 3, a long pin is provided to be connected to the external substrate, and a part of the pin is bent to obtain a buffering effect, thereby improving impact resistance. Even if the influence on the sensor itself is reduced, if tensile stress or torsional stress is applied to the pin, the impact may be transmitted to the detection element etc. held at the tip of the pin. There is concern about damage to the detection element and the like. Further, the effect is exhibited when the gas sensor is connected (attached) to the external substrate, and no effect can be expected for the product before the gas sensor is connected, for example, during connection work. Further, the elastic force of the pin is used to obtain a buffering action, but the effect of this gas sensor can be expected only in one direction (for example, the Z-axis direction), and the remaining two directions (for example, X direction) , In the Y-axis direction), an effect cannot be expected, and the impact is directly applied to the connection portion between the pin and the outside, so that there is a high possibility that a problem such as breakage of the connection portion will occur.

  Accordingly, the present invention has been made to solve such a problem, and increases the degree of freedom of wiring with the outside when mounting and the force applied to the connecting terminals (out leads and electrode pins) with the outside. It is an object of the present invention to provide a gas sensor that can prevent damage due to the above.

  The gas sensor of the present invention is configured to achieve the above-described object, and includes at least a gas-sensitive element and a plurality of electrodes that are electrically connected to the gas-sensitive element at one end to support the gas-sensitive element. A pin, a mount base made of an insulating material that supports each of the plurality of electrode pins from one surface to the other surface, and a region on the one surface side including the gas sensitive element of the mount base are covered. A gas permeable cover member fixed to the mount base in such a manner that each electrode pin penetrates the electrode pin on the side protruding from the other surface of the mount base. A spacer is arranged, and an out lead having a bent portion that extends in a direction parallel to the surface of the spacer and is bent in a direction parallel to the surface is connected to the tip of the plurality of electrode pins. Together with the said out-lead is characterized in that it is arranged in the groove formed in the spacer surface.

  By adopting such a configuration, against the external stress applied to the out lead, particularly the tensile stress in the same direction as the out lead extending direction, the groove wall surface where the bent portion is arranged serves as a stopper, and the stress on the connecting portion The load can be reduced and there is no risk of damage.

  In addition, a pressing member that covers substantially the entire surface of the spacer that supports each outlead can be provided, and the bent portion of the outlead can be held by the spacer and the pressing member.

  By adopting such a configuration, the out lead is firmly held, so that it is resistant to torsional stress, and the out lead and the connection part are not damaged.

  Grooves for supporting the respective out leads formed on the surface of the spacer are provided in a lattice shape, and the bent portions of the out leads can be bent at arbitrary positions along the lattice grooves. Yes, the outlead extension direction can be arbitrarily set.

  By adopting such a configuration, there is no risk of damage to the out lead and the connection part even when stress is applied to the out lead, and the bending direction of the out lead can be set at an arbitrary position, and the out lead extends to the outside. Since the direction can be set arbitrarily, the degree of freedom in mounting can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, damage to the out lead resulting from external stress and the connection part of an out lead and an electrode pin can be suppressed, and a highly reliable gas sensor is obtained.

The perspective view which looked at the gas detection part side of the gas sensor which concerns on this invention facing up. The perspective view which shows the gas sensor of FIG. 1 upside down. Side surface sectional drawing of the gas sensor which concerns on this invention. The top view seen from the out-lead side 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 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 FIGS. This is an example of a catalytic combustion type gas sensor. FIG. 1 is a perspective view of the gas sensor as viewed from the side facing the gas detection portion, and FIG. 2 is a perspective view showing the gas sensor upside down.

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 protrusion 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 a cap 3 fixed to one surface of the mount base is shown in FIG. It 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, pass through the spacer 4, and are parallel to the back side of the holder 1 on the upper surface side of FIG. 2 (also parallel to the other surface of the mount base). ) Are connected to stainless steel out leads 5a, 5b, and 5c. 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. 4 described later.)

  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 holder 12 has a pair of spacer holding pieces 12a (only one of which is shown in FIG. 2) that holds the outer peripheral surface of the spacer 4 at a position facing each other, and a position at which the pressing member 6 faces each other. And a pair of pressing member locking pieces 12b that are pressed and locked to the spacer side 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 the pressing member 6 is placed on the spacer 4 in an overlapping manner, the locking piece portions 12b ₁ formed on both sides of the distal end portion of each pressing member locking piece 12b of the spring holder 12 are indicated by arrows in FIG. When it is bent substantially perpendicularly to the direction, it abuts against the back surface of the pressing member 6, and the pressing member 6 is pressed against the spacer 4 and held by the spring force strengthened by the curvature of the rising portion of each pressing member locking piece 12b. To do. 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.

The internal structure of this gas sensor will be described with reference to FIG.
FIG. 3 is a side sectional view of the gas sensor shown in FIGS. 1 and 2. The holder substrate 11 is a member having a somewhat elongated baseball base 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 7a (the other electrode pin 7a is not shown in FIG. 3 because it is a cross-sectional view) is inserted into 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 8a (the other electrode pin 8a is not shown in FIG. 3 is not shown) is 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. 3, a dome-shaped cap 3 is covered on the upper surface side of the mount base 2 so as to cover the detection element and the compensation element 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.

FIG. 4 is a plan view of the gas sensor of the present invention viewed from the out lead side. FIG. 5 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. The tip portions of the electrode pins 7 a and 8 a are arranged in a state of protruding from the bottom surface of the groove portion 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. Each of the out leads 5a, 5b, and 5c is configured to extend in a direction parallel to the surface of the spacer 4 and to be provided with a bent portion that is bent in a direction parallel to the surface (see FIG. 5). 4 and FIG. 5, the out lead 5a and the out lead 5c have one 90 ° bent portion, and the out lead 5b has two 90 ° bent portions). The out leads 5 a, 5 b, 5 c are arranged in a 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 arranged is filled with an adhesive or the like and fixed.

  With such a configuration, a strong structure can be obtained against external stress applied to the out leads 5a, 5b, and 5c. In particular, for the tensile stress in the same direction as the direction in which the out leads 5a, 5b, and 5c extend, the out leads 5a, 5b, and 5c are not straight but have a bent portion. The wall surface of the arranged groove 4b serves as a stopper, and the direct stress load on the connecting portion with the electrode pins 7a, 8a can be reduced. Particularly, the welded portion with the electrode pins 7a, 8a is damaged. No worries. Further, since this stress is not transmitted to the electrode pins 7a and 8a, there is no influence on the detection elements and the like held at the tip portions of the electrode pins.

  Further, as shown in FIG. 5, a pressing member 6 is provided so as to cover substantially the entire surface of the spacer 4 on the side supporting the out leads 5a, 5b, 5c, and the bent portion of the out lead is formed by the spacer 4 and the pressing member 6. Can be held.

  According to such a configuration, the bent portions of the out leads 5a, 5b, and 5c are sandwiched between the spacer and the pressing member, so that a stronger structure can be obtained. Therefore, the structure is strong against any stress such as pulling and twisting applied from the outside, and the damage to each of the out leads 5a, 5b, and 5c and the connection portion with the electrode pins 7a and 8a is eliminated.

  Further, if the groove portions 4b for supporting the respective out leads 5a, 5b, 5c formed on the surface of the spacer 4 are formed in a lattice shape as shown in FIGS. 4 and 5, the bent portions of the out leads 5a, 5b, 5c are formed. Can be set at an arbitrary position along the lattice-like groove 4b.

  According to such a configuration, in addition to eliminating the risk of damage to the connection portions of the out leads 5a, 5b, 5c and the electrode pins 7a, 8a with respect to the torsional stress applied to the out leads 5a, 5b, 5c, The extending direction of the out leads 5a, 5b, and 5c is not limited to one direction, and one of the out leads can extend in the direction opposite to the extending direction of the other out leads. Can be set arbitrarily. Therefore, it is possible to arrange the out leads according to the mounting form on the external substrate or device, and the degree of freedom in mounting increases.

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 shield board 11 Holder board 11a Opening 11b Protruding part 11c Attachment Hole 12 Spring holder 12a Spacer holding piece 12b Holding member locking piece 12b ₁ Locking piece 12c Fan-shaped portion 21 Slot 22 Slot 23 Slot

Claims (3)

  At least a gas sensitive element, a plurality of electrode pins electrically connected to the gas sensitive element at one end to support the gas sensitive element, and the plurality of electrode pins from one surface to the other surface, respectively. A mount base made of an insulating material that is penetrated and supported; and a gas-permeable cover member fixed to the mount base so as to cover a region on the one surface side including the gas sensitive element of the mount base. A gas sensor comprising: spacers arranged so as to penetrate each electrode pin on the side where the electrode pin protrudes from the other surface of the mount base; and the spacer at the tip of the plurality of electrode pins An out lead extending in a direction parallel to the surface and having a bent portion bent in a direction parallel to the surface is connected, and the out lead is formed on the spacer surface. Gas sensor characterized in that it is arranged in the groove.   2. A holding member that covers substantially the entire surface of the spacer that supports each outlead is provided and held by the spacer and the holding member so as to sandwich the bent portion of the outlead. The gas sensor described.   Grooves for supporting the respective out leads formed on the surface of the spacer are provided in a lattice shape, and the bent portions of the out leads can be bent at arbitrary positions along the lattice grooves. The gas sensor according to claim 1, wherein the extending direction of the outlead can be arbitrarily set.

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