Abstract:
The invention relates to a method for producing an internal combustion engine piston which is provided with at least one cooling channel (12) and at least one reinforced piston ring groove (14) consisting in producing a piston blank (1), in forming a groove (10) provided with a cooling channel (12) and an external ring (11) in said piston blank (1), in filling the cooling channel (12) with are movable material (2), in filling the external ring with a reinforcing material (3) in removing the removable material (2) and in finish-machining the piston. A piston made of aluminum alloy and produced according to the inventive method is also disclosed.
Abstract:
A metering system in a combustion unit having an exhaust-gas chamber and a reducing agent reservoir includes an electrically controllable valve for introducing the reducing agent into the exhaust-gas chamber without using compressed air. The valve has an outlet opening that opens directly into the exhaust-gas chamber. The outlet opening is fluidically connected to the reservoir through the valve. The metering system can be produced with only little technical outlay. The metering system includes a recirculating circuit, and the valve has a holding chamber for the reducing agent. The holding chamber is disposed downstream of the outlet opening in a reducing agent flow direction, and is fluidically connected into the recirculating circuit. The metering system includes a coolant circuit for cooling the valve. The valve and its outlet opening is disposed in the exhaust-gas chamber to position the principal axis of the valve at an angle of less than 90° with respect to a principal direction of flow of exhaust gas in the exhaust-gas chamber. The metering system includes a baffle disposed in the exhaust-gas chamber to cause a change in direction of reducing agent introduced therein. The combustion unit can be a diesel engine, and the reducing agent can be a urea solution.
Abstract:
When determining the amount of a reducing agent solution to be introduced into the exhaust gas of a combustion system, in particular of a diesel engine, for catalytically reducing the nitrogen oxides by the SCR process, the concentration of the reducing agent in the reducing agent solution as well as the parameters characterizing the operating state of the combustion system, the exhaust gas and/or the catalyst are taken into consideration. As a result, the safety margin with respect to a theoretically optimum amount to be introduced that is required to avoid a leakage of reducing agent can be reduced, whereby the conversion rate of the nitrogen oxides is improved.
Abstract:
A static mixer in the exhaust emission control system of an excess-air-operated combustion engine is formed of an expanded grid with a plurality of openings formed between crossbars. Using an expanded grid achieves both good mixing of the exhaust gas with a reducing agent in a short mixing path and properly aligns the exhaust flow.
Abstract:
A device for introducing a liquid reducing agent into an exhaust gas purification system includes a gas line for receiving and carrying a gas, a reducing agent line for receiving and carrying a liquid reducing agent, a mixing chamber for mixing the reducing agent with the gas, the mixing chamber fluidically connected to the gas line and to the aid reducing agent line, a metering valve disposed in the reducing agent line; and a control device for controlling a pressure in the reducing agent line dependent upon a gas pressure in the gas line. The control device can also be used for controlling the reducing agent throughput in the reducing agent line in dependence on the gas pressure in the gas line.
Abstract:
A premixing chamber of a nebulizing device for an exhaust gas purification system serves to mix a compressed gas such as compressed air, for example, with a reducing agent such as urea solution, for example. The premixing chamber is set up on the carburetor principle and includes a compressed gas feed having a taper and a reducing agent feed opening in the region of the taper. The premixing chamber ensures that no deposits originating from the reducing agent can settle in the region of the mixing route. The premixing chamber is provided, in particular, for an exhaust gas purification system of a vehicle fitted with a regulated diesel catalytic converter as well as for stationary diesel engines of up to about 1000 kW (mechanical power).
Abstract:
A method is provided in which the reducing agent, during the starting phase of the internal-combustion engine and during operation with decreasing and, if appropriate, virtually constant exhaust gas temperature, is fed superstoichiometrically in relation to the nitrogen oxide concentration, while taking into account the temperature-dependent storage capacity of a denitration catalytic converter for the reducing agent. The reducing agent is otherwise fed substoichiometrically. In this manner, the catalytic converter is kept at all times at a preferred charge level, so that on one hand it is possible to provide sufficient stored reducing agent for the catalytic conversion and on the other hand it is possible to still have a reducing agent buffer available which avoids slip of the reducing agent. The invention can be used in all internal-combustion engines operated with air excess, such as diesel engines and lean-burn engines.
Abstract:
The invention relates to an extruded solid catalyst body for breaking down nitrogen oxides in the presence of a reducing agent as well as to a process for manufacture of said body. The solid catalyst body has an active material that contains 60 to 87% by weight of an ion-exchanged zeolite containing at least one metal from the group containing Cu, Hf, La, Au, In, V, lanthanoids and transition metals of group VIII of the periodic system, more than 10 to 37% by weight of aluminum oxide and 2 to 10% by weight of inorganic fibers. The solid catalyst body, the active material of which contains a zeolite can be manufactured by extrusion and has a high degree of mechanical stability at a high catalytic activity.
Abstract:
The invention relates to a method for producing an internal combustion engine piston which is provided with at least one cooling channel (12) and at least one reinforced piston ring groove (14) consisting in producing a piston blank (1), in forming a groove (10) provided with a cooling channel (12) and an external ring (11) in said piston blank (1), in filling the cooling channel (12) with are movable material (2), in filling the external ring with a reinforcing material (3) in removing the removable material (2) and in finish-machining the piston. A piston made of aluminium alloy and produced according to the inventive method is also disclosed.
Abstract:
A configuration for decomposing nitrogen oxides in a gas stream includes a plurality of catalytic converters disposed one after the other through which the gas stream can flow. Each of the catalytic converters has a honeycomb structure with many parallel cells through which the gas stream can flow. Each of the catalytic converters also has a predetermined cell density and a predetermined average level of activity defined as a proportion by weight of the catalytically active agent. The predetermined cell density of a second catalytic converter through which the gas stream flows after a first catalytic converter is lower than the predetermined cell density of the first catalytic converter. The predetermined average level of activity of the second catalytic converter is also higher than the predetermined average level of activity of the first catalytic converter. The configuration is preferably used in conjunction with an exhaust gas from a combustion drive unit.