Gas sensitive apparatus

Cross-reference of related applications

This application claims the benefit of US Provisional Application No. 60 / 617,246 filed on October 7, 2004, which is incorporated herein by reference in its entirety for all purposes.

The present invention relates to a gas detector for gas analysis, which is not exclusive, but is particularly useful for analyzing exhaust gas from automobiles or exhaust gas from other internal combustion engines. This device is applicable for the detection or quantitative measurement of individual gases present in the mixture, and is particularly convenient given its small size and low power consumption.

In an automobile engine, it is convenient to be able to detect the presence or concentration of various components in the exhaust gas flow. Such analysis and measurement is used for the purpose of optimizing the amount of fuel and air injected to control the operation of the engine. Providing the engine with the optimum composition of the fuel / air mixture under all operating conditions can minimize fuel consumption and emission of harmful substances from the engine. Besides controlling the engine, gas analysis and measurement can also play a role in the diagnosis of automotive catalytic converters. In order to optimize the performance of the catalytic converter, the amount of fuel and oxygen in the exhaust gas stream should generally be within a certain range.

For example, oxygen, nitrogen oxides (NOx), carbon monoxide, sulfur oxides (SOx), hydrogen sulfide (H)₂Various gases are usually present in the exhaust stream of an automobile engine, such as S), hydrocarbons, ammonia, hydrogen, and water. Numerous products are known that are intended to analyze gas flow using gas sensor devices. A typical gas sensor device uses one or more chemically / electrically active materials as sensor elements, each of which changes its electrical properties when exposed to a particular gas. is there.

One of the complex factors in the process of analyzing and measuring a wide variety of gas components in mixtures such as exhaust gases is exposure to one or more non-gass that give a signal that can serve as analytical data. This can affect the signal from one particular sensor element. For example, a material selected as a sensor to respond to NOx may detect the presence of oxygen or hydrocarbons, in addition to detecting the presence or concentration of nitrogen oxides. This problem involves several different types of data to obtain sufficient data to separate the signal that accurately reflects the presence of one type of sample gas from the unavoidable signal caused by the cross-sensitivity of different sensor elements to the entire gas. It is dealt with by using the sensor elements of.

However, in a gas sensor device composed of a plurality of different sensor elements for dealing with such a problem of cross sensitivity, size limitation may occur depending on the nature of the installation. When gas sensor devices are used in automobiles, there are very strict and demanding size restrictions. Many currently known automotive gas sensors, such as those described in (Patent Document 1), need to be small enough to pass through a circle, if not smaller than a circle with a diameter of 100 mm or less. .. However, in-vehicle automotive diagnostics are not only used as small gas analyzers, but hand-held devices for monitoring all kinds of toxic and harmful gaseous materials are becoming increasingly important. It's coming.

When configuring a size-restricted gas sensor, there is an unavoidable tension between the desire to use as many different sensor elements as possible within the device and the demand for the sensor device to meet the appropriate size restrictions. Inevitably occurs. Each independent sensor element carries the input and output pulses and signals needed to operate all the sensor elements contained within the sensor device, rather than considering only the space occupied by the element itself. The location and arrangement of leads, connectors, and cables are also taken into account. Therefore, it is possible to increase the number of sensor elements that can be used in the sensor device, and at the same time, it is necessary to develop components for the device such as a gas detection device that keep the size of the device within the permissible limit. ..

<patcit num="1"><text>U.S. Pat. No. 5,556,526</text></patcit>

<p> A gas sensor device that accommodates a large number of desired sensor elements and can be configured to accommodate virtually all applicable size limits for use in automotive applications, or other desirable industrial environments. The present invention meets the above requirements by providing a gas detector for use as a component inside. Of course, the use of the gas detector of the present invention in gas sensor devices is not limited to the automotive industry.</p><p> One of the advantages peculiar to the present invention is that a large number of sensor elements and their related electrodes (printing electrodes, etc.) are arranged in a space-saving manner in the gas detection device. Another advantage of the present invention is that in the gas detector, a plurality of conductors, which are sufficient to carry the inputs and outputs of pulses and signals to and from many sensor elements, are arranged in a space-saving manner. By incorporating a large number of sensor elements into a compact compact gas detector, the present invention can identify a wide variety of components in a gas mixture at very low concentrations under virtually any size limiting condition. it can. The gas detector of the present invention is incorporated in a gas sensor device installed in a self-propelled vehicle or in any other desirable type of industrial equipment. These and other benefits are described in more detail below.</p>

<p> One embodiment of the invention is capable of passing through a circle having a diameter of about 100 mm or less; (a) four or more sensor elements and (b) two or more each contacting two or more sensor elements. It is a gas detection device including the electrodes of the above.</p><p> Another embodiment of the invention comprises (a) four or more sensor elements, (b) a first electrode in contact with at least one component of the first group of sensor elements, and (c) a sensor element. Any of the first group of sensor elements, including a second electrode that contacts at least one component of the first group of sensors and also contacts at least one component of the second group of sensor elements. A gas detector whose components are also not components of the second group of sensor elements.</p><p> If the same features are also shown in FIG. 2, the same numbering as the features shown in FIG. 1 is given in FIG. If the same features are also shown in FIGS. 3, the same numbering as the features shown in FIGS. 1 and 2 is given in FIG.</p>

One embodiment of the present invention is an apparatus for analyzing a gas mixture such as those contained in the exhaust gas of an internal combustion engine, and this apparatus can include a plurality of sensor elements. These sensor elements can be mounted on a substrate such as an integral object or a multilayer laminate in order to detect a specific gas contained in the mixture and generate a signal based on the specific gas. The substrate, which is an integral body, is made from a material such as alumina or zirconia as one solid part of the raw material, not by stacking multiple separate layers. In contrast, multi-layer laminates are manufactured by assembling multiple layers together by applying heat and pressure to treat them together. The substrate is typically planar in shape, eg, its cross section forms a rectangle, and the length of one dimension exceeds that of the other by more than 500%. However, the substrate can also have other shapes, for example, its cross section forms a rectangle in which the length of one dimension exceeds the other by less than 500%, or the cross section is trapezoidal, circular, or elliptical. Can also have.

A plurality of gas sensor elements are used in the gas detection device of the present invention, and these gas sensor elements are used so that the input flow of the gas mixture passes over all the gas sensor elements at substantially the same time. An array of individually electrically responsive solid-state sensor elements mounted on the input and output means can be constructed. Although not required, it is preferred that at least one sensor element be provided for each type of individual gas in the mixture being analyzed. However, as mentioned above, additional sensor elements are also provided to cross-check the signals generated by the sensitivities of the individual elements to two or more gases, which may require a large number of sensor elements. The device of the present invention may also include a heater for heating the substrate, such as a heating plate or heating wire mounted on or within the substrate. The heater is powered by a power source connected to a hot plate or heating wire.

The electrochemical interaction between the solid surface of the sensor element and the adsorbed gas species causes a change in electrical conductivity in the sensor element. The sensor element can be manufactured from, for example, a metal oxide semiconductor. The electrical signal generated by the interaction of the gas with the sensor surface is extracted as an output and processed by an analyzer that detects the presence or concentration of various gas components in the mixture. These decisions or calculations are made by lookup tables or algorithmically controlled computational functions, or by advanced deconvolution or neural network techniques.

Different in the gas mixture by placing multiple sensor elements on one or more surfaces of the substrate, multiplexing pulse and signal input and output lines, and providing a common amplifier and analyzer unit. The analysis of gas components can be performed with a sensor device of appropriate size. Due to the small size of the device of the present invention, the sensor device can be installed sufficiently close to the gas source, so that the time when the gas is generated and the gas detection device that is a part of the sensor device come into contact with the gas. There is no significant change in the composition of the gas mixture with time.

The multiplex space-saving layout of the sensor element and the electrodes through which pulses and signals flow in and out of the sensor element accommodates a large number of sensor elements in the apparatus of the present invention. These sensor elements can be made from chemically / electrically active materials such as those described below and can be placed on one or more surfaces of the substrate. Electrodes can be made from metals such as gold, platinum, or palladium, or mixtures of two or more thereof, and can be placed on or inside the substrate. The sensor elements and electrodes on the surface of the substrate can be applied by any of various printing techniques as described below. Placing electrodes inside a substrate by providing multiple layers of "green" tape, one or more layers of which have electrodes, and stacking the layers together to form a multi-layer laminate. Can be done.

A particular embodiment of the space-saving layout of the sensor elements and electrodes can be seen in FIG. A plurality of sensor elements 2 are provided on the substrate 4. A plurality of electrodes 6 connect various sensor elements 2 to the contact terminal 8. The electrodes can complete an electrical circuit that passes through each sensor element. The contact terminal contacts a conducting wire (not shown), which allows an electrical pulse to pass through various sensor elements 2 and receive signals from various sensor elements 2. The signal is sent to a microprocessor for processing as described below.

Due to the multiplexing, the electrodes are shown intersecting each other, which is achieved by the dielectric layer between the intersections.

The gas detector of the present invention can pass through a circle having a diameter of about 100 mm or less, preferably about 50 mm or less, more preferably about 25 mm or less, and most preferably about 18 mm or less.

In one embodiment, the apparatus of the present invention may include, for example, four or more sensor elements and two or more electrodes, each of which contacts two or more sensor elements. For example, electrode A 10 contacts sensor elements A-1 12 and A-2 14, and electrode B 16 contacts sensor elements B-1 18 and B-2 20. As can be seen from the figure, electrodes A 10 and B 12 are in contact with different sensor elements, respectively.

Sensor element A-3 22 and sensor element B-3 24 are used in some cases. As shown in FIG. 1, depending on the estimated difficulty of the immediate gas analysis operation, one or both of these may or may not be incorporated into the device, and this is estimated. The difficulty determines the number of sensor elements required to analyze the gas mixture with the desired degree of detail. Where sensor elements A-3 22 and B-3 24 are present as shown, electrodes C 26 and D 28 are also present as shown. If one or both of the sensor elements A-3 22 and B-3 24 are not present, then there is no corresponding electrode. When the sensor element A-3 22 is present as illustrated, the electrodes A 10 and C 26 can be used to complete the circuit through that element and are shown in the various drawings herein. As described above, the circuit passing through the other sensor elements can be completed in the same manner by using the electrodes adjacent to the respective elements.

It can be seen that in the embodiment in which the sensor element A-3 22 is present, the electrode A 10 is in contact with the three sensor elements. Similarly, in the embodiment in which the sensor element B-3 24 is present, it can be seen that the electrode B 16 is in contact with the three sensor elements. In these cases, electrodes A 10 and B 16 are in contact with different sensor elements.

Another embodiment is shown in FIG. 2, which includes additional sensor elements and electrodes in addition to those described in the embodiment shown in FIG. If the same features are also shown in FIG. 2, the same numbering as the features shown in FIG. 1 is given in FIG. In FIG. 2, the electrode E 30 is in contact with the sensor elements E-1 32 and E-2 34 and is therefore the third electrode in contact with two or more sensor elements. Electrode E 30 is in contact with a sensor element that is different from either electrodes A 10 and B 16.

The sensor element E-3 36 is used in some cases and is shown in FIG. 2, but may or may not be included in the device. If the sensor element E-3 36 is present as shown, the electrode F 38 is also present as shown. If the sensor element E-3 36 is not present, then the electrode F 38 is also absent. When the sensor element E-3 36 is present as shown, the electrode E 30 is the third electrode that contacts the three sensor elements. Even in such a case, the electrode E 30 is in contact with a sensor element different from that of the electrodes A 10 and B 16.

Yet another embodiment is shown in FIG. 3, which includes additional sensor elements and electrodes in addition to those described in the embodiment shown in FIG. If the same features are also shown in FIG. 3, the same numbering as the features shown in FIG. 2 is given in FIG. In FIG. 3, the electrode G 40 is in contact with the sensor elements G-1 42 and G-2 44 and is therefore the fourth electrode in contact with two or more sensor elements. Electrode G 40 is in contact with a different sensor element than A 10, B 16, and E 30.

The sensor element G-3 46 is used in some cases and is shown in FIG. 3, but may or may not be included in the device. If the sensor element G-3 46 is present as shown, the electrode H 48 is also present as shown. If the sensor element G-3 46 is absent, then the electrode H 48 is also absent. When the sensor element G-3 46 is present as shown, the electrode G 40 is the fourth electrode that contacts the three sensor elements. Even in such a case, the electrode G 40 is in contact with a sensor element different from any of the electrodes A 10, B 16, and E 30.

Referring to FIG. 2, electrode J 50 is in contact with sensor elements B-2 20 and E-2 34, and electrode K 52 is in contact with sensor elements A-1 12, B-1 18 and E-1 32. You can see that it is doing. With reference to FIG. 3, it can be seen that the electrode K 52 is in contact with the sensor elements A-1 12, B-1 18, E-1 32, and G-1 42. Therefore, it can be said that each of the electrodes A 10, B 16, E 30, G 40, J 50, and K 52 is an electrode that contacts two or more sensor elements. Furthermore, each of the electrodes A 10, B 16, E 30, G 40 and K 52 can be said to be an electrode that contacts three or more sensor elements, and electrode K 52 contacts four sensor elements. It can be said that it is an electrode.

In the apparatus of the present invention, when the sensor element is installed on the surface of the substrate as described above, the heater can be installed on another surface of the substrate if desired. FIG. 4 shows an example of the heater layout. In FIG. 4, the heater 54 on the surface of the substrate 4 is connected to the electrode 56, and the electrode 56 is connected to the contact terminal 58. The heater may be, for example, a hot plate, may be made of a metal such as gold, platinum, or palladium, or a mixture of two or more thereof, and can be attached by printing or other known techniques.

When the sensor element is installed on one surface of the substrate and the heater is installed on the other surface of the substrate, electrodes are present on both surfaces of the substrate in the apparatus of the present invention. As can be seen by comparing FIGS. 1-3 with FIG. 4, the number of electrodes on the first surface of the substrate can be at least twice, or at least three times, the number present on the second surface. I understand.

As described above, in the apparatus of the present invention, the sensor element can be installed on the surface of one or more of the substrates. In particular, in the case of a multilayer laminate, sensor elements can be installed on two or more surfaces. The material used as the sensor element can be placed on different layers of "green" tape, after which the various layers are combined to form a finally cured laminate, which constitutes the substrate. To. The layer on which the sensor element is placed becomes the surface of the substrate.

The electrodes can be placed on the same layer as the sensor element, or on a layer that is on the inside of the substrate and therefore not the surface. Thus, the electrodes can be placed on one, two, or more surfaces of the substrate and may not be present on the surface. Further, since the sensor elements can be placed on one, two, or more surfaces of the substrate, each embodiment shown in FIGS. 1, 2, and 3 is placed on one surface of the substrate. be able to. As a result, there can be four or more, six or more, eight or more, or ten or more sensor elements on one, two, or more surfaces of the substrate. Therefore, the substrate can include a total of 6 or more, 8 or more, 10 or more, or 12 or more sensor elements.

Yet another embodiment is shown in FIG. 5, and if the same features are also shown in FIG. 5, the same numbering as the features shown in FIG. 1 is given in FIG. In FIG. 5, the sensor element A-1 12 is in contact with the electrode A 10 of the first electrode and the electrode K 52 of the second electrode. The sensor element A-2 14 is in contact with the electrode A 10, and the sensor element B-1 18 is also in contact with the electrode K 52. Thus, electrode A 10 is in contact with at least one component of the group consisting of sensor elements A-1 12, A-2 14 and A-3 22; the same is true for electrode K 52. Although sensor element B-2 20 is not in contact with electrode K 52, electrode K 52 is also associated with at least one component of the group consisting of sensor elements B-1 18, B-2 20, and B-3 24. Are in contact. The components of the group consisting of sensor elements A-1 12, A-2 14 and A-3 22 are all components of the group consisting of sensor elements B-1 18, B-2 20 and B-3 24. is not it.

As can be seen from FIG. 5, electrode A is not only in contact with two or more components of the group consisting of sensor elements A-1 12, A-2 14 and A-3 22, but also of that group. It is in contact with all components.

Yet another embodiment is shown in FIG. 6, which includes additional sensor elements and electrodes in addition to those described in the embodiment shown in FIG. If the same features are also shown in FIG. 6, the same numbering as the features shown in FIG. 5 is given in FIG. In FIG. 6, electrode K 52 is in contact with sensor element E-1 32 and thus at least one component of the group consisting of sensor elements E-1 32, E-2 34, and E-3 36. ing. The components of the group consisting of sensor elements E-1 32, E-2 34, and E-3 36 are all members of the group consisting of sensor elements A-1 12, A-2 14, and A-3 22, respectively; And is not a component of the group consisting of B-1 18, B-2 20, and B-3 24.

The third electrode, electrode B 16, is in contact with sensor elements B-1 18 and B-2 20, and therefore, as can be seen from FIG. 6, electrode B 16 is sensor element B-1 18 and B-. It is in contact with at least one component of the group consisting of 2 20 and B-3 24. However, it can also be seen that electrode B 16 is in contact with two or more components of the group and is in fact in contact with all components of the group. The fourth electrode, electrode J 50, contacts at least one component of the group consisting of sensor elements B-1 18, B-2 20, and B-3, and sensor elements E-1 32, E-2. It is also in contact with at least one component of the group consisting of 34, and E-3 36.

Yet another embodiment is shown in FIG. 7, which includes additional sensor elements and electrodes in addition to those described in the embodiment shown in FIG. If the same features are also shown in FIG. 7, the same numbering as the features shown in FIG. 6 is given in FIG. In FIG. 7, the fifth electrode, electrode E 30, is in contact with at least one component of the group consisting of sensor elements E-1 32, E-2 34, and E-3 36. However, it can also be seen that electrode E 30 is in contact with two or more components of the group and is in fact in contact with all components of the group.

Electrode K 52 is in contact with at least one component of the group consisting of sensor elements G-1 42, G-2 44, and G-3 46. The components of the group consisting of sensor elements G-1 42, G-2 44, and G-3 46 are all members of the group consisting of sensor elements A-1 12, A-2 14, and A-3 22, respectively; It is not a component of the group consisting of B-1 18, B-2 20, and B-3 24; and the group consisting of E-1 32, E-2 34, and E-3 36. The sixth electrode, electrode G 40, is also in contact with at least one component of the group consisting of sensor elements G-1 42, G-2 44, and G-3 46. However, it can also be seen that the electrode G 40 is in contact with two or more components of the group and is actually in contact with all the components of the group.

As is the case with other embodiments of this device, some or all of these groups of sensor elements can be placed on one surface of the substrate, and as mentioned above, the heater is on another surface of the substrate. Can be installed on top. In such cases, the electrodes are placed on both surfaces of the substrate. The number of electrodes on the first surface of the substrate can be at least twice, or at least three times, the number present on the second surface.

Again, as mentioned above, the sensor element can be placed on one or more surfaces of the substrate. In particular, in the case of a multilayer laminate, sensor elements can be installed on two or more surfaces. As a result, there can be four or more, six or more, eight or more, or ten or more sensor elements on one, two, or more surfaces of the substrate. Therefore, the substrate can include a total of 6 or more, 8 or more, 10 or more, or 12 or more sensor elements. The electrodes can be placed on the same layer as the sensor element, or on the inner surface of the substrate. Thus, the electrodes can be placed on one, two, or more surfaces of the substrate and may not be present on the surface.

Other descriptions of the apparatus of the present invention, and how to use it, are described in U.S. Patent Application No. 09 / 977,791 filed October 15, 2001, and U.S. Patent Application No. 10 / 117,472, April 5, 2002. As can be found in the specification, the entire internal use of each of these is incorporated herein by reference.

When a device of the invention is referred to or described as containing, containing, containing, or having certain features, integers, and / or components, it means that such reference or description is clearly the opposite. It should be understood that one or more components other than those explicitly mentioned or described may be present in the device, unless otherwise indicated. However, in another embodiment, the device of the invention may be referred to or described as substantially consisting of a particular component, and in such embodiments, the operating principle or characteristic properties of the device. There are no components in it that substantially change. In yet another embodiment, the device of the invention may be referred to or described as consisting of specific components, and in such embodiments, components other than those mentioned are present therein. do not do.

When the indefinite article "a" or "an" is used with respect to a reference or explanation for the presence of one component in the apparatus of the present invention, it means that such reference or description is clearly the opposite. Unless otherwise, it should be understood that the use of such indefinite articles does not limit the number of components present in the device to one.

<figref num="1">It is the schematic of the multiplex circuit which connects an electrode to a sensor element.</figref><figref num="2">It is the schematic of the multiplex circuit which connects an electrode to a sensor element.</figref><figref num="3">It is the schematic of the multiplex circuit which connects an electrode to a sensor element.</figref><figref num="4">The layout of the heater on the substrate in the apparatus for analyzing the gas mixture is shown.</figref>