JPS60501873A - Wide range air fuel ratio sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Wide range air fuel ratio sensor Technical field The present invention relates to the determination of the composition of gas atmospheres.

Background technology The high-temperature oxygen sensor is used in determining the stoichiometric air-fuel mixture in the open air bus of an automobile internal combustion engine. It is known to use sensors. The stoichiometric mixture is the amount of air present in the charcoal The mixture has just enough oxygen to react with the amount of water that remains, so the remaining acid Both elements and hydrocarbons are in minimal amounts. Theoretical air-fuel ratio (A/F = air amount /Amount of fuel) Habo! It is 14.6. For example, if the engine is a theoretical quantity (A /F<　14.6) If the operation was leaner, it would have burned in the whistle of the internal combustion engine. The charge will be air-rich and the waste gas will have a substantial partial pressure of oxygen. if If rich operation occurs (A/F (14, 6), the exhaust gas will be filled with unreacted or It will have partially reacted hydrocarbons and a very low oxygen partial pressure.

In particular, the equilibrium oxygen partial pressure in the exhaust gas changes as operation moves from lean to rich operation. Therefore, it can change in large numbers (as many as 20 in size). This big change is caused by Forms the basis for detecting the stoichiometric air-fuel ratio with an oxygen sensor. This is 5 years old The electrical output of the sensor is then connected to an electrically controlled carburetor or is fed back to the fuel injection system. Depending on the engine type, luck in this regard may vary. The controlled exhaust air minimizes gas emissions and maximizes engine performance. Demonstrate a reasonable compromise to do so.

Utilizing a single oxygen electrochemical concentrator cell (usually made from zirconium oxide), A suitable reference atmosphere (usually air High temperature oxygen sensors are known that require the use of air). These devices contain oxygen Gives an output (electromotive force) proportional to the natural logarithm of pressure. Oxygen partial pressure ((lower than the device) Large changes in oxygen partial pressure at the stoichiometric point allow the device to operate effectively despite severe nitrification.

U.S. Patent Nos. 6,948,081, 3,738,641, 4,112,8 No. 96, No. 4,210,509 and No. 4,107,091 discuss this type of acid. It is an elementary sensor.

U.S. Pat. No. 6,907.657 to Hagin and No. 3,5 to Subecil et al. No. 14,377 relates to the measurement of oxygen (02) concentration using a solid state electrochemical device.

For example, for applications at high temperatures (>500°C) encountered in furnaces or open air tubes of automobiles. The active material in these devices is the ceramic used for the conduction of oxygen ions. It is a mixture of zirconium dioxide. Electrochemical cells made from this material have high Suitable for use in sensitizing and pumping oxygen at warm temperatures.

The operating method of Heijin's equipment is an oxygen calculation method in which the oxygen partial pressure is determined based on the extraction sample standard. It is written as a law (・ro.

A constant current is applied over time for the purpose of electrochemically pumping most of the oxygen out of the volume. Add to the electrochemical cell forming part of the volume enclosure for tρ. The atmosphere around 8 Before pumping due to leakage, the volume is 1C installed.1. reactor. Reduced partial pressure of oxygen within the volume An additional electrochemical cell, which serves as a sensor for the It has a signal from the volume (see hazing in Figure 4) to indicate that it has been sufficiently emptied. do. When knowing the warm temperature, enclosed volume, pumping current and time, is the ideal S law? Calculate the number of oxygen molecules in the enclosure (C). Proportional to oxygen partial pressure. If a constant pumping current is used, the pumping time t ρ is proportional to the oxygen partial pressure. If a constant current is not used, then when pumping The integral of the pumping current is proportional to the oxygen partial pressure.

) The Isin device has an output linearly proportional to the oxygen partial pressure. This is for example Provides an output (electromotive force) proportional to the natural logarithm of oxygen molecules - F, In (PO2) It is superior to a single oxygen concentrator battery used as a sensor.

A possible drawback of the Hagin device is response time. For the second measurement process, the enclosed During the pumping of oxygen, the leakage connecting the volume to the surroundings must be small; A significant amount of oxygen can be absorbed into molecules without leaking into the volume (i.e. without accidentally increasing tv). This will cause an error in the calculation. However, if the leakage becomes smaller, After draining, apply tv to the surroundings for a long time to re-establish the leak itself with the volume. Ru. If changes in the ambient oxygen partial pressure occur rapidly relative to this replenishment time, then If so, the equipment would not be able to follow these changes in repeated operations.

In the case of the teachings of Johns U.S. Pat. No. 3.69.8,384, the objective is to It is to measure the oxygen partial pressure of . This is done while keeping the voltage of the sensor battery constant. This is done by measuring the pumping current of an electrochemical cell.

However, the flow rate of the feed gas must be kept constant. What if the flow If the velocity is to be designed to vary, it should be relatively precise to keep the flow velocity constant. There is a clever flow control circuit. This plan also uses a reference atmosphere, with a negative air flow rate of Relatively unsuitable for automotive applications where air pressure varies substantially with rotational speed .

Figures 1 and 2 of the drawings show an ion conductor with thin platinum electrodes 2 and 3. The zirconium oxide material 1 defines the volume surrounded by the additional ceramic structure 4 1 shows a known oxygen pumping sensor forming an electrochemical cell. The surrounding atmosphere leaks The opening 5 provides itself within the volume. Battery 7 is connected by conductors 8 and 8'. attached to the electrode. Voltmeter 10 and ammeter 9 measure the voltage drop across the pump battery. provided to determine the current flowing under and through it. U.S. Patent No. 3, Although similar in construction to Figure 5 of No. 907.657, the operation is different. pump out here and the pumping voltage ■ to remove oxygen from the enclosed volume 6 until the current saturates. Add. Saturation current is proportional to oxygen partial pressure or concentration.

This is a steady state device. When steady state is reached, the oxygen passing through the leak opening 5 The flow is equal to the proportional constant of the pumping current time. Platinum electrode 2 or cathode In conjunction, the leak holes only allow a limited (saturated) amount of oxygen to enter. is pumped electrochemically from the volume every unit time, so the current saturates. saturation The current value depends on the properties of the electrode 2, and the calibration of the device is based on the fact that these properties are responsible for the sintering of this thin layer. Subjected to flow, so that the amount of wear and tear varies.

For some engines, it is recommended to run them at a leaner stoichiometric A/F ratio to reduce fuel consumption. is useful. The oxygen partial pressure varies in a systematic manner within the dilution range, and this is due to the dilution A/ A criterion for determining F can be formed. However, appropriate dilution A The changes in oxygen partial pressure in the /F range are not large (compared to the changes that occur near the stoichiometric amount) Therefore, a suitable oxygen sensor with a sensitivity greater than the natural logarithm of the oxygen partial pressure will provide the desired A Desirable for accurate Mll determination in the /F range.

Oxygen partial pressure sensors for engines operating at lean stoichiometry are Rick U.S. Pat. Nos. 4,272.331 and 4,272,330; As taught in U.S. Pat. No. 4,272.629 by Earl, E., Hetrick et al. Ru. The sensor (shown as prior art in Figure 6 of the drawings) is placed entirely in the open gas stream. The two oxygen ion conductors are partially enclosed by an enclosed volume 13. It has electrochemical cells 11 and 12, a bonde cell and a sensor cell. the rest of the structure The structural part is a hollow ceramic tube 14. The battery is made of a lamic glue-like material. attached to the end face of the

Small holes 17 in the surrounding structure allow a volume of open gas with a determined percentage of oxygen. Let it leak inside.

Conductive wires 18 are attached to electrodes 15 attached to each side of electrochemical cells 11 and 12. Be it.

The patents of Hetrick and Hetrick et al. various external circuitry coupled to the sensor to permit operation of the method with the state method; The product is listed. When operated in one of these ways, the device will It provides linear or large sensitivity to the sensor, allowing for lean operation compared to single cell sensors. It has a big effect. Additionally, various methods have low temperature sensitivity and, in one case, absolute It provides other useful features such as being independent of pressure changes.

In these methods, oxygen flows at a rate given by the Bonde cell current, pumped electrochemically into or from a volume enclosed by a At the same time, oxygen leaks Diffusion into or out of a volume by pores. Oxygen flows through leaks and is pumped out Since changing the oxygen partial pressure in the volume with respect to the surroundings, the electromotive force (-v8) is Develops across batteries. The ambient oxygen partial pressure, which is sequentially proportional to the A/F ratio, is Depends on the relationship between.

Additionally, in addition to the previously discussed stoichiometric and lean air/fuel operation, rich stoichiometric It may be desirable to run the engine at In this range - like carbon oxide Increasing water with partially reacted amount of hydrocarbons (HC) and decreasing A/F The prime can serve as the ...1] constant of A/F. When using oxygen pumping batteries , must be able to produce a measurable response with a partial response (-HC). A/F can be determined by measuring the amount or rate of oxygen required.

Thus, U.S. Patent Nos. 4,224,116 and 4,169,440 The current passing through the device and the Electrochemical analysis of oxygen in zirconium oxide along with f measurement of the potential difference across the device. A single cell structure combined with pumping is described. However, such a single Battery equipment can be used in calibration (buoys) or You would suffer serious losses of deterioration.

Cross the pump battery, which is a critical parameter of A/F established for these devices. The potential drop will be significantly influenced by the amount of battery electrodes. This is the rate at which oxygen is needed. Some potential difference is required to ensure passage through thick or thin electrodes. Because it happens, it happens. Thus, the electrode contribution to the potential difference is due to the electrode sintering under high temperature use. change over time to become better or worse. Sara K crosses the battery. The ohmic contribution to the potential difference is close to temperature resulting in a possible price and performance penalty. It will vary exponentially with temperature requiring restrictions. Hetrick and Hetli The effects of the two cell structures described by the patents of Bond et al. This means that the potential difference is not the limiting parameter, and this leads to electrode deterioration and and reduce the effects of temperature.

In this way, different filter sensor structures and different external circuit components can be used, especially at side-heated A/ It is recognized that this method is particularly effective for A and /F measurements in the F range. wider range The current sensor used in the does not have the desired characteristics. Often over a wide range of rich and dilute A/F values. Exhaust air that has a theoretical amount that can direct the engine's A/F and integrates the most useful properties. It would be desirable to have a gas oxygen sensor.

There are several problems that the present invention overcomes.

Demonstration of invention According to an embodiment of the present invention, a signal instructing the A/P of the internal combustion engine to generate exhaust gas 4) In V), the exhaust gas, oxygen, and N sensors connect the first and second electrochemical cells. have Two electrochemical cells are placed in a spaced apart, partially enclosed volume. product limits the distance between the batteries. The volume communicates with the exhaust air through the opening. 1st and A first side of each of the electrochemical cells and the second electrochemical cell are exposed to the partially enclosed volume. No. The second side of the electrochemical cell of No. 1 is exposed to exhaust gas. The second electrochemical cell The two sides are exposed to the reference atmosphere. In some cases, the reference atmosphere shall be the ambient atmosphere. is desirable. In other cases, the reference atmosphere is an enclosed volume of metals, metal oxides. This is desirable.

In accordance with embodiments of the present invention, the apparatus is capable of producing stoichiometric air fuel values, richer, leaner and Different measurements are taken to determine the exhaust gas A/F over a wide range of values with close values. used in conjunction with fixed techniques. The device therefore has a [-free] air-fuel sensitivity characteristic. . Additionally, the cell structure allows the use of three ranges of special effect measurement techniques.

Brief description of the drawing Figures 1, 2 and 6 show the structure of a prior art electrochemical oxygen pumping device. , FIG. 4 is a schematic cross-sectional view of the sensor according to the first embodiment of the present invention, and FIG. A graphical illustration of sensor cell voltage, VB versus air-fuel ratio A/F for the sensor shown in Figure 6 shows the sensor cell voltage at various rich air fuel values for the sensor according to Figure 4, ■ Figure 7 is a schematic diagram of the pump battery current versus pump battery current, and Figure 7 shows various air Required to hold sensor cell voltage at reference voltage for fuel ratio, A/F Figure 8 is a graph of the bonded battery current, Outline of a sensor device for an external circuit component according to an embodiment of the present invention for an A/F that operates if The main drawing, FIG. 9, is a schematic cross-sectional view of a sensor according to a second embodiment of the present invention.

Implementing the invention - the best mode for carrying out the invention From FIG. 4, the air fuel (A/F) sensor 110 is made of zirconium oxide (Zr02 ) Treated solid ionic conductors of oxygen such as yttrium oxide (Y2O3) What is the electrochemical cell 111 equipped with the disk-shaped electrolyte 112? The battery 111 is also Two thin porous catalytic platinum electrodes with conducting wires 114 attached It has 113. Similarly, electrochemical cell 121 includes electrolyte 122, electrodes 123 and and a conducting wire 124. The electrochemical cell 111 is powered by a thin hollow spacer 125. Since it is separated from the gas chemical cell 121, the enclosed volume is limited. battery 111 has a small hole or leak hole 126 in it, so that the surrounding atmosphere, the exhaust gas, has a volume V can be provided within itself.

Electrochemical cell 121 has a ring-like tubular profile closed at one end, thereby The reference volume is limited and one side of the battery 121 is exposed to the reference atmosphere. especially flat discs The shaped electrolyte 122 has a tubular structure 131 attached thereto and has a ring-like profile. to be accomplished. As a result, one side of the sensor is exposed to the exhaust gas and the -side is exposed to the reference atmosphere. be exposed. Alternately, the electrolyte itself has a ring-shaped profile. Similarly, the battery 112 and spacer 125 may be made from a single piece of material or may be made from two pieces as shown. Constructed from separate component parts. The sensor support structure 128 is located between the exhaust gas and the reference atmosphere. The seal is attached to the duct wall 127 to allow for attachment to the wall, as well as for structural support and protection. have protection. Sensor support structure cover 228 provides easy access to sensor 110 for exhaust air. Allow proximity. Conductors 114 and 124 are attached to external circuit components V) Support structure It passes through the body 128. The heater 129 maintains the A/F sensor 110 within the desired operating temperature range. be set up as such.

From FIG. 9, it can be seen that another embodiment according to the present invention has an air standard on one side of the battery 121 in FIG. is replaced with a metal or metal oxide mixture. The air fuel sensor 140 in FIG. 142 and an electrode 143 attached to a conducting wire 144. have Sensor 140 also has a voltage coupled to electrode 147 coupled to conductor 148. A second electrochemical cell 145 having a solution 146 is included. Spacer 149 is a battery 141 is separated from the battery 145. The hole 150 in the electric wire M141 surrounds the sensor 140. Provide a passageway from the working air atmosphere into the enclosed volume. Cup-shaped holding structure 151 holds the metal-metal oxide mixture 152 in close proximity to one side of the electrochemical cell 145. Ru. The air-fuel sensor 140 is located entirely within the exhaust gas stream and is connected to the production pipe wall 154. attached to an attached support structure 153; Use of air fuel sensor 140 No seal for sensor 140 is required between the exhaust air and the outside atmosphere, making manufacturing easier. The entire device is submerged in waste gas, giving simplicity and reduced cost of accessories.

Referring to the operation of the apparatus of FIG. 4, the air fuel sensor 110 has a stoichiometric Exhaust gas over a wide range of values with richer, leaner and closer values It is used with two different measurement techniques to determine the air-fuel ratio. Therefore, The device is considered to have "free" sensing characteristics. First, steady state oxygen - The pumping method can be used for a wide range of rich and lean air-fuel ratio values. secondly , the single electrochemical cell technology described above is used at near stoichiometric capacity. Structure of the device shown in Figure 4 Because the structure allows the use of multiple measurement techniques, the functional effect of each technique is unique in its use. This is achieved within a range of fuel ratios. Single electrochemistry for measuring near-stoichiometric A/F The use of batteries is well known and is described in U.S. Pat. No. 3,948,081 to Wetzell et al. Lean A/F & sensing pumping technology using two battery structures taught by The use of No. 4,272,300 and 4,272,331 The bush is shown. The use of two battery pumping techniques to sense dense A/F is) Title of invention by IJ Lack et al.: "Steady State Method for Determining Rich Air/Fuel Ratio" It is further discussed in a pending application filed on the same day.

The air-fuel sensor 10 of FIG. When used in conjunction with internal combustion engine operation near stoichiometric and lean operation, Line 114 is disconnected from battery 111 and air-fuel sensor 10 detects the stoichiometric air-fuel ratio. As a single electrochemical cell sensor as described above in connection with sensing; for use in cattle;

The equilibrium oxygen partial pressure for the exhaust gas, PEx, is the contact reaction of the cell 121 in the volume V. is established at the response electrode 123.

Together with the oxygen partial pressure of the air standard, P yo, becomes equal to 0.2 atm t, and the electromotive force, ■ 8 occurs across the cell 121 and is given by the Nernst equation.

V = (RT / 4F) In (PREF / PEX)' (]) R is the gas constant, T is the absolute warm temperature and F is the Faraday constant. Corresponds to P Yu As the air-fuel ratio decreases, the electromotive force of the cell increases as shown in FIG. Waste air The strong variation in the electromotive force of the cell within this range is due to the stoichiometric and For air-fuel ratio operation near the lean range this makes this a relatively simple and desirable technique. . However, larger or smaller air-fuel values The change in electromotive force becomes very small for the desired effective sensor operation.

An effective method of operation for lean air-fuel ratios greater than about 15.5 is described in U.S. Pat. 272,329, 4.272,330 and 4,272,331. Steady state, fluctuating or transient operating methods are described. These methods and oxygen is pumped into a volume surrounded by a pump battery, such as battery 121. or pumped out of the volume and into other "sensor" batteries, such as battery 111. Monitor the changes in the introduced electromotive force. Oxygen is pumped out through leak hole 126 and The changes in oxygen pressure in v from the combined effects of oxygen diffusion and oxygen diffusion yield a systematic relationship. For sensing oxygen with high sensitivity in the dilute range and Bonde battery current ■2, A "sensor" with a basic battery is generated between the electromotive force and the electromotive force.

In particular, in steady-state operating methods, external circuit components must pull just enough oxygen from V. The electric current is passed through the bonded battery 121 so that it will move, so it is named V8. A constant sensor cell emf is established. The percentage of oxygen increases increases the pumping current required by the oxygen percentage and the corresponding A/F has a measurement of In particular, you will understand the following:

IP=a PEX (1e-v8/v0) =・+21Vo=RK/4F and σ is a proportionality constant that limits the rate at which oxygen can diffuse into V through the leak hole. . For example, σ is proportional to the oxygen diffusion coefficient and the area of the leak hole. In this way, exactly Keep Vs constant by always passing through sufficient power, IP~PF, X~A/ F thereby prepares to sense the high-sensitivity A/F. for automotive use However, this technique has insufficient temperature and absolute pressure sensitivity.

The cited patent covers both a sensor and a pump battery completely submerged in waste gas. The equipment operation for each is described. The sensor 110 may be a bonded electrochemical cell 12. When the external electrode of No. 1 is exposed to the reference atmosphere with high oxygen concentration as shown in Figure 4, However, they have similar operating methods. The reason is that the effect of the standard atmosphere causes the pump battery 121 to Add a small increase to the total potential difference across. However, the pump battery Only currents with no potential drop across the battery are critical for equipment operation. Ru. Therefore, all of the dilute operation methods described in these patents apply to electrochemical cells 121 is used as a Bonde battery, and the electrochemical cell 111 is used as a sensor battery. This is achieved in conjunction with the current structure. Air denser than the theoretical amount (A/F < 14.7) During operation with a fuel-to-fuel ratio, the partially reacted HC a-transformation increases as the air-fuel ratio decreases. increases thereby giving a measurement of the air-fuel ratio.

In a similar approach to operation used for lean operation, the air fuel sensor The method for determining the rich air fuel ratio of S11[+ is the ratio given by It has to cause oxygen to be pumped into v from the reference atmosphere at. At the same time, the acid in V The elementary partial pressure continues through the leakage hole 126 through oxygen diffusion and into the volume V through the leakage hole 126. The internal catalytic reaction electrode 123 and the partially reacted hydrocarbons that diffuse through the reaction and 113 chemical reactions.

As Bonde battery current, increases, the equilibrium partial pressure of oxygen in the volume V increases as the electrochemical cell This electromotive force, named 1, V Yu, increases when an electromotive force is introduced across 111. The magnitude of the force is PREi, the reaction of F pumped oxygen and partially reacted carbonization. It is close to the equilibrium oxygen partial pressure in the volume V due to hydrogen being replaced by Pv. Given again by Equation 1. In this case, record the electromotive force from PV>PEx. The number is introduced by the pumping action and reversed during lean air heat ratio measurements.

Figure 6 shows the electromotive force introduced at different rich air-fuel ratio values, ■6 vs. pumping current, I A drawing of P is shown. The electromotive force is low for small pumping currents and increases with ■. For air-fuel ratios lower than 1°, the ever-increasing threads of oxygen combine with the hydrocarbon enemy. must be pumped into the volume V in order to carry out the critical reaction. In particular, any electrochemical to reach the reference value VA(REF) (maintained in external circuit components). The value of ■2 required to generate an electromotive force in the battery 111 is empty as shown in Figure 7. This will increase systematically by reducing the air-fuel ratio (i.e. becoming richer). A calibration curve such as provides the basis for determining the rich dry fuel ratio. VA (REF) The choice (will be primarily influenced by numerous design considerations, but is rare for simplicity's sake) For thin-sensing operation V) Steady-state method (τ) is chosen equal to the criterion used. However, the symbol is opposite. The size of the hole is an increasing function of the battery volume and the leakage hole size. It is.

A/F γ11 constant and engine A/P feedback control are for lean operation. This is achieved using a similar method used in A similar circuit shown schematically in Figure 8 is Attached to both batteries. In Figure 8, the support structure is shown for clarity. not present. Resistors R1, R2 and capacitor C control the gain and frequency response of amplifier A. control, so that A occurs across battery 111 with a value equal to VA(REF”). Sufficient pumping current TP is always generated to maintain power. Resistor R3f Since the voltage is included in the battery circuit, the voltage is 1 (crossing 3) with the voltage g-1-v. It is determined by setting the voltage to 4. When using the calibration curve in Figure 6, air Fuel ratios will be drastically changed, and standard electronic components will be used. It is compared with the value of 2 required for the desired air-fuel ratio. If the current is too If it is high or low, the intake fuel will increase or decrease, respectively, and this will cause This allows feedback control to be achieved. Also, the temperature sensor 140 indicates )(3) to form an input to the modified circuit component 141; If necessary, adjust (2) up to the temperature compensation 11f.

In summary, stoichiometric rich or lean operation is suitable for rich or lean conditions. acid into or from the enclosed volume until a predetermined vA(REF) is achieved. It is achieved by drawing out the basics. Used electronically, such as on an on-board computer Measurement of pumping current and desired value (main comparison) for possible rich and lean calibration order Electrical Sent to control carburetor or fuel injection system.

Due to the highly exothermic nature of the hydrocarbon-hydrogen reaction, very small amounts of pumped oxygen The theoretical quantity, which is only one year old, causes wide variations in vA at will. Therefore, the highest end of this range A suitable technique is to use a conventional single electrochemical electrode near the atmospheric oxygen partial pressure with a reference electrode. Use the pond. -7-Ead back control with a known value, and desired dryness 4 ・Achieved by comparing the output of the battery with the voltage corresponding to the l ratio, the city: It can also be used electronically in a computer's storage device.

Its connection, single device, sensor 110 (lean and concentrated using main pumping operating method) Both voids over a wide range of thick conditions and close to stoichiometric with a single electrochemical cell High sensitivity to air-fuel ratio.

Alternately, remove oxygen from ■ and return to open air.'' - Using battery 111 as Bon 0, It is effective to use the battery 121 as sensor 1 for lean operation. It is possible for some people to make small changes to the results. For example, in steady state it is Recognize.

In this way, any value, 斥, is always fixed (Pya,.

(temporarily assumed to be constant) Vl, by adjusting 5 Kr. , although it is offset by a certain amount from the Wagaro value in Equation (2), it is still is proportional to.

Shrewd selection of ■8 will still allow convenient lean driving with high sensitivity.

The effect of this reversal of bonding and sensor cells is as follows: Eliminating the current flow in the battery 121 used will result in a.

If the current flow is very large in the oxygen ionic conductor, the electrolyte or electrode It is well known that deterioration is life. This is a sequential open circuit Eito ζ゛ light exhibition Since a false or false emf is generated, the next operation is compromised as a sensor battery. Let's do it 1. Unfortunately, in this case the sensor battery electrode cannot be submerged in the air wash. The fact is that the absolute exhaust pressure is relative to the small feeling of 1 g-'l what--I gas fuel ratio calibrated amount produce a line.

In Example 1 shown in FIG. 2 (e.g. nickle/nickel oxide, copper/copper oxide) Can be replaced. The two battery structures have a metal-metal oxide physical compound in the sustaining structure 151. 4 except that the reference electrode 147 is kept close to the battery 145. It is similar to that. In this embodiment, batteries 145 and 141 are connected to the sensor and It is suitable for dilute and stoichiometric operation and acts as a Bonde cell. typical The effective oxygen partial pressure, PM/Mo(REF), is dilute at a standard metal-metal oxide reference electrode. Since it is almost smaller than P under the conditions, the substantial electromotive force (e.g. 200-500 mV) appears across the sensor battery 145 at =0. Oxygen is pump battery 1 41 from the volume v9, this emf will decrease. standard When carrying a suitable emf of this reduced range as a value, U.S. Chamberlain No. 4.272 , 329, a similar analysis was used in The output current is proportional to the percentage of oxygen in the gas, which was previously discussed. Indicates that it can serve as a lean air-fuel ratio sensor as in the case. Operation close to theoretical quantity Therefore, the pump battery 141 is separated and the open circuit emf of the sensor battery 145 is monitored. be seen. For other single cell sensors, the output air path is narrow due to the stoichiometric amount. with large changes in cell emf, which is suitable for determining air-fuel ratios within a range of cormorant. The pumping method for rich air-fuel ratio detection ensures that sufficient oxygen is available. request.

Various modifications and variations may occur to those skilled in the art to which this invention pertains. It will happen without you. For example, the shape of an electrochemical cell can vary from the shape disclosed herein. It can be changed. These disclosures essentially rely on technology to advance the technology. and all other variations are appropriately considered to be within the scope of the invention.

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Claims (1)

[Claims] 1. Air-fuel sensor that measures a wide range of air-fuel ratios, both rich and lean stoichiometric. In the sensor, the sensor; a first electrochemical cell; a second electrochemical cell; vapor chemical cells are interconnected at spaced locations defining a volume therebetween; a first electrochemical cell with a first side exposed to the volume and exposed to the sample surrounding gas; a second side configured to connect the volume and the sample surrounding gas; said second electrochemical cell; and said second electrochemical cell; has a first side surface exposed to the volume and a second mouth side exposed to the reference oxygen partial pressure. An air fuel sensor comprising: 2. A front panel for supporting said first and second electrochemical cells in spaced apart locations. a spacer device coupled to the first and second electrochemical cells; an electrochemical cell is located in a negative air flow, and one side of said second electrochemical cell is exposed to ambient air; a support structure for mounting said air-fuel sensor in a vehicle's negative air system to wherein said first electrochemical cell is substantially planar; said second electrochemical cell is substantially planar; Electrochemical cells are also generally planar; an enclosed volume is the first and second electrochemical cell. The spacer device has a hollow structure so as to be provided between the cells; the opening is in the front. The air fuel according to claim 1, wherein the air fuel is in the first electrochemical cell. charge sensor. 6. said support structure device is generally cylindrical and extends in an opposite direction from said spacer device; The second electrochemical cell extends from the periphery of the second electrochemical cell. Air fuel sensor as described in section. 4 metal/gold in close proximity to said second electrochemical cell to establish a reference oxygen partial pressure. Claims further comprising a support device for containing the group oxide compound. An air-fuel sensor according to scope 1. 5 Negative gas producing signal indicating the air-fuel ratio of the operation of the internal combustion engine producing negative gas In a gas oxygen sensor; the first and second electrochemical cells are spaced apart from each other; defining a partially enclosed volume therebetween, said volume communicating with negative gas through an opening; each first side of the first and second electrochemical cells being exposed to the volume; a second side of the first electrochemical cell is exposed to negative gas; a second side of the electrochemical cells is exposed to a reference ambient atmosphere; each of said electrochemical cells is exposed to a reference ambient atmosphere; A first electrode is provided on each of the first side surfaces, and a second electrode is provided on each of the second side surfaces. Negative gas oxygen 7゜ characterized by 6. The second electrochemical cell is exposed to the surrounding external atmosphere adjacent to the negative gas system. Install said sensor in the exhaust gas system of the internal combustion engine to allow the sides of the engine to be exposed. further comprising a support structure coupled to the second electrochemical cell for attaching the The exhaust gas oxygen sensor according to claim 5, characterized in that: 7 Exhaust gas producing signal indicating the air-fuel ratio of the operation of an internal combustion engine producing exhaust gas In the gas oxygen sensor, the exhaust gas oxygen sensor is located within the exhaust gas; a first and a second electrochemical cell are mutually spaced and partially enclosed volumes therebetween. A: the volume has communication with the exhaust gas through an opening; a side of each cell 1 of the second electrochemical cell is exposed to said volume; a second side of the pond is exposed to waste gas; a second side of the second electrochemical cell is exposed to waste gas; Characterized by exposure to metal/metal oxide compounds that act as a reference oxygen partial pressure Exhaust gas oxygen sensor. 8 the metal/metal oxide compound is selected from the group of nickel/nickel compounds; The exhaust gas oxygen sensor according to claim 7, characterized in that: