Abstract: A process serves for recoating a deactivated catalyst coating of a catalyst for converting harmful constituents from the exhaust gas of an internal combustion engine, particularly in a motor vehicle. In this process, washcoat and/or noble metal compounds are sprayed by means of an aerosol into the catalyst. The noble metal compounds are subsequently brought into their elemental state by means of a reducing medium flowing through the catalyst, after which the washcoat applied is dried by heat treatment or calcination. In an apparatus for carrying out the process, a first line for a carrier gas and a second line for the washcoat and/or the noble metal compounds are provided. The first line is arranged at least partly in a region before the catalyst within the second line and at its ends nearest the catalyst is provided with an atomization device.

Abstract: A process serves for recoating a deactivated catalyst coating of a catalyst for converting harmful constituents from the exhaust gas of an internal combustion engine, particularly in a motor vehicle. In this process, washcoat and/or noble metal compounds are sprayed by means of an aerosol into the catalyst. The noble metal compounds are subsequently brought into their elemental state by means of a reducing medium flowing through the catalyst, after which the washcoat applied is dried by heat treatment or calcination. In an apparatus for carrying out the process, a first line for a carrier gas and a second line for the washcoat and/or the noble metal compounds are provided. The first line is arranged at least partly in a region before the catalyst within the second line and at its ends nearest the catalyst is provided with an atomization device.

Abstract: A method, and an apparatus for carrying out the method, for purifying exhaust gases from internal combustion engines is provided. The engines having a catalyzer system which includes a first catalyzer and at least one second catalyzer, arranged downstream of the first catalyzer, for the conversion of HC, CO and NO.sub.x exhaust gas constituents. Exhaust gases flow through both catalyzers during the entire operating period of the engine. The first catalyzer is suitable for at least the catalytic conversion of HC and CO exhaust gas constituents. In a first step of the method, the first catalyzer is operated over-stoichiometrically during the cold starting phase in order to reduce the HC and CO emissions and, in a second step of the method with .lambda.-controlled stoichiometric exhaust gas composition, the catalytic conversion of the exhaust gas in the first catalyzer is at least largely de-activated and takes place in the second catalyzer.

Abstract: In a method and apparatus for reducing hydrocarbon emissions from an internal combustion engine during its cold-starting phase an adsorber, which adsorbs hydrocarbons below a desorption temperature and desorbs them above the desorption temperature, is arranged in a bypass conduit to the exhaust conduit and the exhaust gas is passed through the bypass conduit and the adsorber below the desorption temperature of the adsorber, and the bypass conduit is closed when a catalytic converter arranged close the engine in the exhaust conduit upstream of the bypass conduit reaches operating temperature and remains closed at least until a catalytic converter arranged downstream of the adsorber has reached operating temperature.

Abstract: A method, and an apparatus for carrying out the method, for purifying exhaust gases from internal combustion engines is provided. The engines having a catalyzer system which includes a first catalyzer and at least one second catalyzer, arranged downstream of the first catalyzer, for the conversion of HC, CO and NO.sub.x exhaust gas constituents. Exhaust gases flow through both catalyzers during the entire operating period of the engine. The first catalyzer is suitable for at least the catalytic conversion of HC and CO exhaust gas constituents. In a first step of the method, the first catalyzer is operated over-stoichiometrically during the cold starting phase in order to reduce the HC and CO emissions and, in a second step of the method with .lambda.-controlled stoichiometric exhaust gas composition, the catalytic conversion of the exhaust gas is at least largely de-activated and in the first catalyzer takes place in the second catalyzer.

Abstract: A motor vehicle electrical system has an electrical machine with an on-board power supply generator function. The electrical machine can be operated, in a first mode, as an on-board power supply generator, having a regulator for setting the excitation current for the electrical machine, and having an electrical load having a comparatively high power consumption, for example a heating device for an exhaust gas catalytic converter. A changeover switch, by means of which an output of the electrical machine can optionally be connected to an on-board power supply cable or to the load, as well as a control unit for controlling the regulator and changeover switch optionally in the first mode or a second mode, is provided so that the electrical machine is connected to the on-board power supply and the regulator regulates the operating voltage at an on-board power supply voltage. Alternatively, the electrical machine is connected to the load and the regulator regulates the operating voltage at a higher nominal value.

Abstract: The quality of the external air is determined by means of a pollutant sensor. The quality of the internal air is determined by calculation taking account of the air quantities introduced from outside into the internal space. A decision between air supply operation and air recirculation operation is then made on the basis of a comparison of the air qualities inside and outside. The pollutant sensor is preferably located in a casing whose internal space is accessible to gases through an opening which is preferably sealed by a gas-permeable membrane.

Abstract: A self-optimizing control method for optimizing the fuel/air ratio under non-steady conditions in an internal combustion engine is described; in this method, a probe is provided both before and after the catalyst. Control quantities and the time during which the post catalyst probe shows an undesirable fuel/air ratio are stored for certain specified engine-operating conditions in the non-steady range. When the same engine operating condition is repeated, reference is made to the stored control quantities and time and the control quantity is varied in the direction of the correct fuel/air ratio. The time now obtained is compared with the stored time and, if the time has decreased, the new control quantity and the new time are stored. The control values are iteratively corrected by repeating these procedures, when the same engine operating condition reappears, until the time reaches a minimum.

Abstract: An exhaust gas filter for Diesel engines that consists of a monolithic filter block made of a porous ceramic material having a plurality of ducts extending in the flow direction of the exhaust gases, said ducts alternately being closed by plugs in order to force the passage of gas through the duct walls into adjacent ducts. In the case of this exhaust gas filter, the filter block is divided into zones having a decreasing porosity in the flow direction of the gases, and the plugs which force the passage of the gas through the duct walls are each arranged in the area of the zone border. Filters are preferred that have two to four zones of decreasing porosity. The exhaust gas filters are manufactured in that a filter blank that has the largest desired porosity is immersed in a solution or suspension of a porosity-reducing agent up to the desired zone border and is subsequently dried and is possibly burnt. Preferred agents for reducing the porosity are water glass solutions or cordierite suspensions.

Abstract: An exhaust gas filter for Diesel engines that consists of a filter block made of a porous ceramic material, and a plurality of ducts extending through said filter block that extend in the flow direction of the exhaust gases. The ducts in each case are alternately closed at their upstream or their downstream end, whereby the exhaust gases are forced to penetrate a filtering separating wall between two ducts. The closing means at the downstream end, are arranged so that they are staggered with respect to one another in the flow direction; in particular they are staggered by about 5 to 150 mm. The staggered arrangement of the closing means reduces the danger of a thermal damage to the filter block during the burning-off of the deposited soot.

Abstract: A method for testing and adjusting catalytic exhaust gas emission control systems of internal combustion engines, in which the fuel-air-ratio is regulated by means of a .lambda.-probe (control-probe) arranged in the exhaust gas stream upstream of the catalyst, whereby the exhaust gas stream is measured downstream of the catalyst by means of a further .lambda.-probe (test-probe). The voltage average value and amplitude magnitude of the signal produced by the test-probe are determined and serve for adjusting the operating point of the control system and for the recognition of the catalyst efficiency.

Abstract: A system is provided for measuring the amount of oxygen in exhaust gas emitted by an internal-combustion engine. The system includes an exhaust pipe for conducting engine exhaust gas and a probe for determining the oxygen content of engine exhaust gases. The exhaust pipe has a side wall formed to include an aperture for continuously discharging a portion of the engine exhaust gas flowing through the pipe. The system further includes a support housing for positioning the probe at a location outside of the exhaust pipe in proximity to the side wall aperture so that the probe is exposed to the engine exhaust gas portion discharged through the aperture and for collecting exhaust gas in a space surrounding the probe. The aperture is sized to permit exhaust gas collected in the support housing to be reintroduced into the exhaust pipe so that collected exhaust gas will be exchanged continuously with exhaust gas flowing through the exhaust pipe.

Abstract: A method and apparatus for preventing an overheating of an exhaust gas purification block for internal combustion engines in case of a high proportion of combustible gas components in the exhaust gases, in which the exhaust gases are adapted to be conducted past the exhaust gas purification block by way of a controllable by-pass line; at least during the periods when the by-pass line is opened, air preferably in the form of an air jet directed opposite to the normal exhaust gas flow is blown into the line leading into the exhaust gas purification block whereby preferably the air jet passes over the inlet opening of the exhaust gas purification block in a transverse direction.