Abstract: To detect detonations in the combustion chamber of an internal combustion engine, the sensor system is constructed as a unit that may be threadedly engaged with the combustion chamber wall, the unit including an antechamber in the region near the combustion chamber and a detector being disposed at the base of the antechamber. The sensor system further may be equipped with a heater for burning off contaminations. In a further embodiment, at least one filter disc is disposed in front of the detector, so that a selective processing of the received optical signals is possible.

Abstract: A method and apparatus is proposed for obtaining a control variable for the closed-loop control of the fuel-air ratio of the operating mixture of internal combustion engines, in which a threshold-current sensor of known structure is used. By means of varying the measurement voltage present at the threshold-current sensor by voltage amounts which correspond to a change in oxygen concentration to be expected in association with a change in operational state, the time behavior of the threshold-current sensor, which is essentially sluggish, is compensated for and it becomes possible to use it for rapidly-functioning closed-loop control systems in internal combustion engines.

Abstract: To permit a layer construction, which is inexpensive and lends itself to mass production manufacture, a solid electrolyte body, in plate-like construction, with electrodes at either thereof is positioned in a housing with a portion thereof extending in the region where it is exposed to gases to be sensed; a porous cover is applied on one of the electrodes, the porous cover having a predetermined diffusion resistance to oxygen molecules. A flat insulating plate of approximately the same dimension as the solid electrolyte plate is positioned flat thereagainst, and a flat layer-like electrical heating element is secured on the flat insulating plate or, in other embodiments, against another insulating covering on the other side of the heating element as well, close to the electrodes and adjacent the plane surfaces of the body.

Abstract: An apparatus is proposed for controlling the exhaust recirculation rate in an internal combustion engine, in particular an engine with auto-ignition, which includes preferably one mixture valve in the area of the discharge opening of the exhaust recirculation line and which is characterized in that the control is accomplished via the mixture valve position ahead of the inlet valves in accordance with the concentration of at least one component of the air-exhaust gas mixture and/or at least one component of the exhaust gas. Thus it is possible to operate the engine with a relatively emission-free exhaust. An exhaust gas reservoir is further provided, with which peaks in the exhaust gas concentration due to a dynamic driving mode can be intercepted. Finally, it is also proposed that the exhaust recirculation be realized solely via a pressure, which can be controlled in open-loop or closed-loop fashion, in the exhaust line by means of a valve.

Abstract: To apply a measured quantity of air to the electrodes applied to a plate-like solid electrolyte body, which may be a chip on a carrier or may, itself, form the carrier, grooves, flutes, ducts, or depressions are formed in the carrier and/or a cover plate, the grooves terminating at an edge portion with access to the gas to be supplied, and having a size such that their clear height is preferably in the lower micron region, and a width, preferably under 1 mm, and particularly between 0.2 and 0.4 mm. The higher limits are applicable to apply, for example, air to a reference electrode, to apply ambient oxygen thereto; the lower limits are appropriate when operating the sensor as a polarographic sensor, in which the diffusion limited current, upon application of a bias voltage, is an analog measure of the oxygen concentration in the gas, and the gas supply to the electrode must be suitably controlled to prevent saturation conditions.

Abstract: A method and system for controlling the temperature of a heat measuring sensor such as an oxygen sensor located in the exhaust line of an internal combustion engine so that the oxygen sensor will operate within optimal operating temperature. To accomplish this, a heating system including a control mechanism is provided for the oxygen sensor which adjusts the temperature of the oxygen sensor by controlling the output of a heater during the operation of the internal combustion engine according to characteristic engine operating conditions which have an effect on the temperature of the oxygen sensor, the most significant of which is engine load status. These conditions are sensed as a quantity by probes located so as to measure such operating conditions and send a signal to the control mechanism and its sensor heater.

Abstract: To measure partial oxygen pressure in gases, particularly exhaust gases of automotive-type combustion engines, a solid electrolyte plate of elongated rectangular configuration has at least one electrode pair applied to a single surface thereof, which is exposed to the measuring gas. Preferably, the gap between electrodes is elongated, by forming the electrodes in comb-interdigited form. A thermocouple - temperature sensor can be applied between connecting tracks for the electrodes which extend longitudinally of the electrolyte plate towards the other end thereof, through a sealing mass holding the plate within a housing, the other end forming, simultaneously, a connection terminal for connection to an electric connector or plug. A heating element can be placed on the obverse side of the plate, preferably in the position in the gap between the electrodes.

Abstract: To facilitate mass production and permit ready introduction of a substance which provides an oxygen partial pressure reference level, for example the oxygen in ambient air, an elongated plane flat plate-like solid electrolyte body is provided with electrodes thereon, and one of the electrodes is covered by a trough-like cover element to form the reference electrode, the space beneath the trough-like element and the electrode itself being available for the substance which may, but need not be, the oxygen of air, and may be a solid material providing a reference oxygen partial pressure level. The cover plate may, itself, be made of solid electrolyte material and may form a portion of another sensing element, so that a plurality of sensing elements can be superimposed in sandwich-like fashion. A heater element can be applied to a flat plate element of the assembly where desired. The sensors can operate in the potentiometric or polarographic mode.

Abstract: To improve the response speed of an electrochemical oxygen sensor, particularly for automotive use, to sense the oxygen content in exhaust gases, and which can be operative either as a polarographic sensor (requiring application of a voltage thereto), or as a potentiometric sensor (having one catalytically active electrode and another which is less catalytically active), an elongated insulating carrier plate (29), for example of a ceramic, has layer electrodes (30, 31) applied to one major surface thereof and a layer of solid electrolyte material (32) over the electrodes, so that the electrodes will be embedded in the solid electrolyte material. The carrier plate (29) is of a material pervious to oxygen molecules. A gas-impervious insulating cover (33), for example of a ceramic glass, covers the layer of solid electrolyte material (32). A heating element (34) protected by a protective cover (35), for example of aluminum oxide, can be applied against the gas-impervious cover layer (33).

Abstract: To provide a pre-heated sensor which is capable of heating the sensing element exposed to gases to a temperature of above 400.degree. C. and preferably above 500.degree. C.

Abstract: An electrical heating element 35, 35' is located in a thin walled, closed metal tube or sleeve 37, 37' which is packed with a packing material 38, 38' of good heat conductive, insulating properties; the electrical heating element is a spirally wound resistance heater embedded in the insulating packing. A solid electrolyte body 11, 68 surrounds at least a portion of the thin walled metal sleeve and is positioned in heat exchange relation therewith. The solid electrolyte body may be a closed tube 11 or may be applied as a ring element 68 over the thin walled metal tube with an insulating material layer 66 interposed.

Abstract: An electro-chemical sensor to determine the oxygen content of exhaust gases, particularly from internal combustion engines. The sensor contains a tubular solid electrolyte closed at one end having a catalytically active layer on the outside to be exposed to the exhaust gas. The inside of said solid electrolyte tube is exposed to the ambient air and is provided with a contact portion arranged at the bottom of said solid electrolyte tube. The sensor contains an elongated axial center electrode which is pressured against the bottom (closed end) of the inside of the tubular solid electrolyte, preferably by means of a compression spring which may be mounted internal of said center electrode or external thereof. The central electrode comprises an insulating body having a heating element in the area which will be adjacent the portion of the solid electrolyte in contact with the exhaust gases. Additionally the central electrode also carries an electric lead to said contact portion.

Abstract: To avoid temperature shock and mechanical damage to oxygen sensors with ion conductive solid electrolytes exposed to the exhaust gases of internal combustion engines, a catalyst, for example in the form of aluminum oxide pellets having a catalyzing surface layer, is located to surround the oxygen sensor, or just in advance of the oxygen sensor in a bypass pipe, branching off from the exhaust gas pipe of the engine to take samples of the exhaust gases so that the sensor and catalyst form an assembly, or sensing combination. The catalyzing layer may be platinum, or a platinum metal, or an alloy of platinum with aluminum, cobalt, nickel, or chromium, or may be mineral wool, or wool of glass, or asbestos fibers having their surface coated with any of the foregoing catalysts.

Abstract: A portion of the exhaust gas of an internal combustion engine is returned to the induction manifold through an exhaust gas recycling line. This recycle line contains one or more orifice plates to create a measurable pressure drop when gas is flowing. The gas flow through the recycle line may be interrupted in controlled manner by a valve, particularly a magnetically actuated valve. The pressure drop across the orifice plate or plates is sensed by pressure-responsive electrical switches which provide input signals for a logical circuit that energizes a signaling device to warn the operator of a malfunction in the exhaust gas recycling system.

Abstract: A portion of the exhaust gas of an internal combustion engine is returned to the induction manifold through an exhaust gas recycling line. This recycle line contains one or more orifice plates to create a measurable pressure drop when gas is flowing. The gas flow through the recycle line may be interrupted in controlled manner by a valve, particularly a magnetically actuated valve. The pressure drop across the orifice plate or plates is sensed by pressure-responsive electrical switches which provide input signals for a logical circuit that energizes a signaling device to warn the operator of a malfunction in the exhaust gas recycling system.

Abstract: The inlet and outlet ends of a catalytic reactor are instrumented with oxygen sensors. A change of the fuel-air concentration of the combustible mixture is indicated by a jump in the output voltage of the sensors; the voltage of the inlet sensor changes before that of the outlet sensor and the greater the time difference between these changes, the higher is the catalytic activity of the reactor. When a repeatable and constant engine condition is reached, the fuel-air mixture is abruptly changed and an electronic circuit enables a logical circuit which controls a signal lamp. If, during a predetermined time interval, the outlet sensor also changes its output voltage, indicating a time difference which is too short, the warning signal is energized and the operator is alerted to the insufficient level of reactor activity.