RU2208174C1 - Converter - Google Patents

Abstract

FIELD: mechanical engineering; internal combustion engines. SUBSTANCE: invention relates to exhaust systems of internal combustion engines, particularly, to catalyst converters. Proposed catalyst converter contains housing with inlet, central and outlet parts, adapter branch pipes, catalytic monoblocks and expansion gasket placed in clearance between housing wall and catalytic monoblocks. Housing consists of two halves with strengthening ribs in form of convex and concave folds and/or radii of sheet material in central part. Widening inlet and outlet parts located between circumference and oval have lemniscate form of surface. Ratio of parameters of lemniscates outlet branch pipe and similar inlet branch pipe is found as a_outi/a_ini = 0,2-0,8; where a is parameter of lemniscate defining distance from beginning of coordinate to its focus. System of compensating radii is provided at butt joint of housing central part with inlet and outlet parts. EFFECT: improved efficiency and reliability of converter owing to correlation of geometric parameters of inlet and outlet parts of converter and their geometrical outline. 4 cl, 4 dwg

Description

 The invention relates to engine building, mainly to exhaust systems for internal combustion engines (ICE), in particular to catalytic converters.

 Known neutralizer, which contains a metal housing, inside of which a catalyst is installed, held by a mounting mat placed between the housing and the ceramic block, see the description of European application 366484, publ. 05/02/90. The disadvantage of this technical solution is the deterioration of the holding properties of the gasket from preventing displacement of the ceramic block in the housing. In addition, strips of metal fabric are separate structural parts, and additional time and material are required for their manufacture and installation, which complicates the assembly technology and increases the material consumption and cost of the structure.

 Known is taken as a prototype converter containing a housing with input and output parts, adapter pipes, catalytic monoblocks and a thermally expanding gasket located in the gap between the housing wall and catalytic monoblocks, the housing consisting of two halves with reinforcing ribs in the form of convex and concave folds and / or the radii of the sheet material in the central part, see the description of patent application GB 2048104 A. Although this technical solution simplifies the assembly technology and reduces the material consumption and cost of cons ruktsii, but it has its drawbacks. So, when the gas flow passes through the monoblock, the main load on the monoblock from the movement of gases is experienced by its central part along the axis of the flow, the action of this load weakens to the periphery of the monoblock from the axis. Thus, the main load to neutralize the gas flow and gas power load in combination with temperature falls on the central part of the monoblock. Which in turn affects the efficiency of the converter and the effective time of the converter. The main feature of the assembly operation according to this invention is that the assembly installation must provide a mode of supply of forces for closing the half-shells with a speed of not more than 2 mm / s. This mode of closure speed is determined by the following. To ensure optimal mounting density of the assembly at a given surface density of the material of the thermally expanding gasket, the thickness of the gasket during assembly should decrease by at least 1/3 due to compression. Given the porous structure of the gasket material, the gasket is compressed during assembly due to the release of air from the pores of the material. In this case, the exit of air from the pores of the material through the surface plane of the gasket is difficult, since one plane of the surface of the gasket is adjacent to the catalytic monoblock, and the opposite plane to the inner surface of the housing. The exit of air from the pores at the ends of the strip is impossible, since an adhesive layer is applied to the ends of the strip. Therefore, the main way for air to escape is through the joint of the gasket, i.e. through the entire length of the strip, which increases the time for air to escape from the pores. If the installation of the half-shells is carried out at a higher speed, then the air does not have time to leave the gasket pores and all the compression force applied to the half-shells will be transmitted through the gasket that does not have time to compress to the ceramic monoblock, which will lead to its destruction. All this increases the time of the manufacturing process of the converter, which in turn leads to an increase in energy consumption during its manufacture. Increases the time of the manufacturing process of the Converter and the additional operation of applying glue, which further increases energy consumption and increases material resources.

 The task to which the invention is directed is a more uniform distribution of the exhaust gas flow rate in normal sections of the converter units, i.e. organize a region of increased pressure in the outlet section, the so-called back-up, aligning pressure plots along the channel of the block, which has a beneficial effect on the distribution of flow.

 The expected technical result is to increase the efficiency and reliability of the converter due to the ratio of the geometric parameters of the input and output parts of the converter of their geometric shapes.

This is achieved by the fact that the converter contains a housing with inlet and outlet parts, adapter pipes, catalytic monoblocks and a thermally expanding gasket located in the gap between the housing wall and catalytic monoblocks, the housing consisting of two halves with reinforcing ribs in the form of convex and concave folds and / or the radii of the sheet material in the central part, with the expanding input and output parts located between the circle and the oval (between sections in the form of a circle and an oval), have the shape of erhnosti generators with a lemniscate. The ratio of similar parameters lemniscates outlet and inlet and _O is defined as _i / _Rin and _i = 0,2-0,8, where a - parameter lemniscate determining the distance from the origin to its focus. And at the ends of the nozzles or on one there is a spherical flange. The neutralizer has brackets for attaching it to the power unit and a heat shield, and at the junction of the central part of the body with the input and output parts there is a system of compensation radii.

для любой точки на i-й образующей, где a, ai - параметр лемнискаты, a φ, φ_i- угол между радиусом - вектором ρ, ρ_i в этой точке и осью нейтрализатора. При этом отношение параметров кривизны соответствующих сечений выходной а_{вых i} и входной a_{вх i} расширяющихся частей патрубков определяется как а_{вых i}/a_{вх i} = 0,2-0,8.The surface shape between the sections of the inlet and outlet nozzles from a circle to an oval is formed according to generators in the form of special curves - a lemniscate, with the position of each point of which can be determined by the formula

for any point on the ith generatrix, where a, ai is the lemniscate parameter, a φ, φ _i is the angle between the radius - the vector ρ, ρ _i at this point and the axis of the neutralizer. In this case, the ratio of the curvature parameters of the corresponding sections of the output a _{output i} and input a _{I i of the} expanding parts of the nozzles is determined as a _{output i} / a _{I i} = 0.2-0.8.

 In FIG. 1 shows a general view of the converter.

 In FIG. 2 is a view along arrow A.

 Figure 3 is a section at the junction of the Central and input parts of the half-housing.

 In FIG. 4 is a diagram of the distribution of a gas stream perpendicular to the longitudinal section of the axis.

От соотношения параметров входной части 6 и выходной части 8 нейтрализатора зависит (при заданном типе каталитического блока и прочих равных условиях) уровень противодавления и степень равномерности распределения скоростей потока отработавших газов в нормальных сечениях каталитического моноблока нейтрализатора. Специально подобранное соотношение между отношениями ρ_вх входного и ρ_вых частей корпуса позволяет организовать (при выполнении условия по ограничению противодавления) область повышенного давления в выходной части корпуса, т.н. "подпор", выравнивающий эпюры давлений по каналам каталитического моноблока, что благотворно сказывается на распределении потока. Следствием такого конструктивного решения является возможность оптимизации загрузки каталитического слоя дорогостоящими редкоземельными элементами и уменьшение термической нагрузки на локальные области блоков. Оптимальное соотношение достигается при а_{вых i}/a_{вх i} = 0,2-0,8.The converter consists of a housing 1, adapter pipes 2 and 3 of a thermally expanding gasket 4, a catalytic unit 5. Housing 1 has an input part 6, a central part 7 and an output part 8 and consists of two stamped halves - half-shells with reinforcing ribs in the form of convex 9 and concave 10 folds or radii of the sheet material in the central part, as well as a system of compensation radii at the joints of the central part 7 with the inlet part 6 and the outlet part 8. Catalytic monoblocks 5, thermally expanding, are axially mounted in the housing 1 rokladka 4 placed in the gap between the housing wall 1 and the catalytic monoblocks 5. At the ends of the pipes or one is spherical flange 11. The nipples themselves may be spherical flanges 11 for angular position error compensation or not. The fixing role is played by the bracket for fastening the converter to the power unit of the car (not shown in Fig.). The compensation radius system consists of three radii R ₁ , R ₂ , R ₃ (see Fig. 3) to ensure a guaranteed minimum clearance h between the oval line of intersection of the outer surfaces of the catalytic monoblock 5 and the inner surface of the housing 1. The sum of the radii is correlated as R ₁ + R ₂ + R ₃ ≥ H + h. The input part 6, expanding as the output 8, represents the surface between the sections in the form of a circle 12 and an oval 13 (see Fig. 2) with generators 14 in the form of special curves - a lemniscate with variable curvature values of the radius vector

The level of back pressure and the degree of uniformity of the distribution of exhaust gas flow velocities in normal sections of the catalytic converter monoblock depends on the ratio of the parameters of the input part 6 and the output part 8 of the converter (for a given type of catalytic unit and other equal conditions). A specially selected ratio between the ratios ρ _in input and ρ _output parts of the housing allows you to organize (if the conditions for limiting backpressure), the region of high pressure in the output of the housing, the so-called "backwater", aligning pressure plots along the channels of the catalytic monoblock, which has a beneficial effect on the distribution of flow. The consequence of such a constructive solution is the possibility of optimizing the loading of the catalytic layer with expensive rare earth elements and reducing the thermal load on the local areas of the blocks. The optimal ratio is achieved when a _{output i} / a _{I i} = 0.2-0.8.

In FIG. Figure 4 shows pressure plots for the channels of block 15 for _{output i} / a _{in i} = 0.2-0.8 and 16 for _{output i} / a _{in i} = 1.0.

 The manufacture and assembly of the Converter is as follows. A monoblock with a thermally expanding gasket is installed in the first half-shell of the converter. Then, the first sub-half-shell is connected to the second half-shell, with a certain effort acting on the selected half-shells until the half-shells are in close contact, and then welding is performed. To do this, first the first half-shell is installed in the cradle of the assembly unit (not shown in FIG.), Then the assembled catalytic monoblock 5 with a thermally expanding gasket 4 is placed in the “shell” of the second half-shell. The second half-shell is placed on top of the assembled monoblock and exerted force until they come into firm contact. For a 2-block converter, the assembly device must develop a force of up to 2000 kg. Assembly is carried out on a special press with continuous monitoring of the compression force of the half-shells. After the contact of the half-shells, they are spot-welded, after which the assembled body is removed from the assembly unit and fed to the welding unit for welding the entire perimeter in order to ensure the tightness of the converter housing 1.

The device operates as follows. Exhaust gases containing harmful impurities through the inlet pipe 2 enter the Converter housing 1, pass through the cells of the catalytic monoblocks 5 and exit the outlet pipe 3 already basically without harmful components. During the passage of exhaust gases through the cells of the catalytic monoblocks, redox reactions occur, as a result of which harmful impurities (СО, Cx, Нy, NO _х ) are converted into harmless compounds (СО ₂ , Н ₂ O, N ₂ ). In the process of passing through the exhaust gas converter, the thermally expanding gasket 4, under the influence of heat from the flow, tends to increase its volume due to a special component. Thus, the pressure on the outer surface of the catalytic block 5 increases, elastic blocking of the block in the housing occurs, isolating it from vibration and shock loads. When the temperature drops, the surface pressure curve passes to the hysteresis branch, remaining at a higher level - the gasket continues to hold the block tightly.

The effect of reducing the concentrations of harmful components in the exhaust gases after the catalytic converter blocks is achieved as a result of oxidation and reduction reactions taking place in the presence of catalysts (at a temperature of 200 - 950 ^o С) on a developed surface of the substrate with a certain range of air-fuel ratios at the engine inlet.

 The efficiency indicators of catalytic reactions are determined by the surface area of the stream - catalyst phase transition, the flow rates in individual channels of the catalytic unit, their distribution, the temperatures of the stream and catalysts, the concentrations of the constituent components of the gas stream, the loading of the block with catalysts, and the properties of the carrier layer. The neutralizer has brackets for attaching it to the power unit and a heat shield.

 The proposed invention solves the problem of improving the reliability and durability of the converter, simplifying the technology of its assembly, reducing material consumption and cost of construction.

 It does not require the use of additional materials and labor for its manufacture and installation.

Claims (4)

 1. A catalyst containing a housing with an input, central and output parts, adapter pipes, catalytic monoblocks and a thermally expanding gasket located in the gap between the wall of the housing and the catalytic monoblocks, the housing consisting of two halves with reinforcing ribs in the form of convex and concave folds and / or the radii of the sheet material in the Central part, characterized in that the input and output parts represent the surface between the sections in the form of a circle and an oval with generators in the form of lemniscates.  2. The neutralizer according to claim 1, characterized in that at the ends of the nozzles or on one there is a spherical flange.  3. The neutralizer according to claim 1, characterized in that it has brackets for attaching it to the power unit.  4. The Converter according to claim 1, characterized in that it has a heat shield.

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