HUT74859A - Multifunctional sound-absorbing for petrol vehicles - Google Patents

Abstract

The invention relates - besides noise deadening - to rendering the rear muffler of gasoline-powered vehicles suitable for decrease in health hazardous effects of the gases in the exhaust system, both in itself and in combination with lambda -controlled or not lambda -controlled (so-called "uncontrolled") noble metal catalysts through filtering out the lead and other metals containing swept particles and by subsequent metallurgic regeneration of the metals or metal compounds therefrom, as well as through catalytic afterburning of the hydrocarbon (CxHy) containing fog or smoke filtrated deposit particles to carbon dioxide and water. As for its subject matter, the invention can be regarded as improvement to the technical solutions that can be learnt in the Hungarian patents Nos. 203 218 and 210 012 since it ensures within the 5,5-10,5 pores/cm region the inhomogeneous porosity of the electrolyte-coated ceramic tubular monolith mounted concentrically in the rear muffler and contributes to the afterburning of the combustible filtrate separated in the rear muffler increasing in the air excess too by means of a device depending on the gas-treating converter type.

Description

MULTI-FUNCTIONAL SOUND DETAILS FOR PETROL VEHICLES

Dr. József Kerti, Budapest Filed on April 7, 1995 The inventor is the same as the applicant

FIELD OF THE INVENTION The present invention relates to the use of a silicon-containing noble metal catalyst in the exhaust system of a gasoline vehicle, in addition to enhancing the silencer, to reduce the health hazard of the gas, alone or in combination with an λ-controlled or unregulated , followed by metallurgical regeneration of metals and / or metal compounds by catalytic post-combustion of carbon monoxide (C _x H _y ) or carbon monoxide and water by filtration of the hydrocarbon (C _x H _y ) mist, or by chemical capture of chloride, cyanide and sulphide compounds. In terms of its subject matter, the present invention is further developed from the solutions disclosed in Hungarian patents 203 219 and 210 012. These patents are valid at the time of the disclosure of the present invention as well as the state of the art.

Justification of the task

Although described in the aforementioned patents, they have proved to be suitable for the purpose of the present invention, but have been developed for the following reasons.

C _x Hy filtrate requires high efficiency, perfect afterburn to ensure partial blockage of the porous ceramic substrate and the resulting excess choking (excess tensile pressure), as well as to avoid secondary loop contamination due to the filtrate. There are several reasons to consider the possibility of secondary pollution. When jumping power increases (eg overtaking a laden vehicle uphill), the gas flow suddenly increases and can drive unburned C _x H _y particles out of the final drum. In addition, the continuous load may raise the temperature of the gas in the end drum to above 300 ² C, which contributes to the sublimation of the more volatile filtrate components of 25 C _x H _y . Other secondary environmental and occupational safety problems may arise from the disposal of end-of-life, end-of-life drums, eg. also in metallurgical processing. All this can be prevented by accelerating the afterburn and preventing the C _x H _y filtrate from coking.

As generally described in Hungarian Patent No. 210,012, a satisfactory C _x H _y filtrate afterburner can be provided if the gas flowing through the filter zone consisting of a porous ceramic carrier and an electrolyte train contains oxygen for at least part of the operating period, i.e., λ> 1.00. This is the case for conventional (non-noble metal catalyst, so it can run on leaded petrol) and unregulated catalysts, thus ensuring that the 5 C _x H _y filtrate, although not continuous but periodically sufficient, is described in EP 210 012. due to the special catalytic effect described (i.e., adiabatic local and temporal temperature fluctuations in the flowing gas). In this way, there is little chance of an increase in tensile pressure and drift of the C _x H _y filtrate, since this can only occur with exceptionally long idle time or boiling at stop and go. However, such a mode is uncommon and uncommon.

The situation is more serious nowadays than in controlled (controlled) λ probe catalytic converters worldwide. Today, most countries only produce new petrol cars in this version. As a result of the regulation, the 15 air to fuel ratio in the carburetor averages 14.9 kg air / kg gasoline and this changes only marginally depending on fuel quality. This satisfies the condition λ = 1.00, so the condition λ <1.00 is the rich mode, while the condition λ> 1.00 is the lean mode. As a result of the control, the condition λ = 1.00 is met in all modes, so that no enrichment occurs during cold start, cold run, deceleration and deceleration periods (eg the extra power required for acceleration is provided by motor control technology).

One of the main tasks of the present invention is to enable the post-combustion of combustible filtrate in the end drum of controlled vehicles, and to prevent its accumulation.

Description of the Invention

In order to accomplish the objects set forth, it has been realized that it is primarily necessary to provide excess air to the end drum in controlled mode, i.e., to mix air with the exhaust gas before it flows into the end drum.

In practice, there are two basic technical variants of solving this problem, depending on the mode of air delivery of the controlled catalytic systems.

One variant consists in introducing preheated air into the noble metal catalyst zone between the reduction and oxidation stages. The aim of the measure is to reduce nitrogen oxide as much as possible according to the reaction 2 NO + 2 CO = N ₂ + 2 CO ₂ and not to interfere with excess oxygen. In the case of excess air, carbon monoxide would not deprive oxygen of nitric oxide according to the prescribed reaction, but would react with oxygen in the air. In this variant, the oxygen required for the post-combustion of the C _x H _y filtrate is provided together with the addition of preheated air, i.e. by increasing the auxiliary air supply (preferably by valve adjustment). In practice, the need for additional air, i.e., its flow rate, is determined experimentally or theoretically. The experimental determination is based on the measurement of the concentration of CO and 5 TOC in the exhaust gas as a function of the supply air flow rate. The minimum is the airflow at which the concentration of combustible components in the waste gas cannot be reduced by further increasing the airflow. Such an increase would not be technically justified either because of the unwanted cooling of the gas mixture or the additional cost of preheating the air. Theoretical determination of the supply air requirement is done by 10 calculations. This requires that the requirement of λ = 1,05 ± 0,03 be met, taking into account the air supplied together with the carburate and the auxiliary air.

In most modern control systems, the optimum airflow for NO _X reduction and post-combustion is not achieved by auxiliary air technology, unless 15 By narrowing the λ-window very narrowly, a very good approach to the λ = 1.00 condition. This is made possible by state-of-the-art oxygen sensor redox electrodes. In this variant, due to the stoichiometric air supply, post-combustion of the CxHy filtrate is not ensured, since some of the oxygen that is theoretically sufficient for this is removed from the final drum along with the exhaust gas. Therefore, the auxiliary air must be introduced into the gas immediately before the end drum whenever the catalytic converter system is not operating in an auxiliary air version. This is most easily accomplished by a diaphragm valve fitted to the pipe section in front of the end drum.

Feeding the auxiliary air to the end drum has been found to require neither preheating nor forced flow (nozzle), since, as explained in Patent Specification 210 012, the tumble pressure of the insert drum is negligible, so that the pressure in the drum fluctuates with the temperature of the gas. higher or lower than the external pressure. Since the post-combustion of the C _x H _y filtrate is not continuous (as in the noble metal catalyst zone), it has been found that satisfactory post-combustion can be achieved by providing air inlet through the valve only at lower internal pressures.

In order to solve this problem, it was also found that for the efficient and rapid post-combustion of the C _x H _y filtrate, it is desirable to promote the adiabatic catalysis described in U.S. Patent No. 210,012 by rendering the porosity of the ceramic drum insert inhomogeneous. The said patent has an experimental porosity of 20 ± 2 on an experimental basis

PPI (7.1 - 8.7 pores / cm), but also indicated this range as tolerable and non-prescriptive. Adiabatic catalysis in quasi-homogeneous pores was achieved by the gradual uneven pore distribution due to repeated hydration - dehydration of the coating and uneven deposition of filtrate. The local species volume of flowing gas fluctuates with the local pore size, and where the local species volume decreases, the local pressure and thus the temperature increase, so that the ignition temperature for a given excess air is accurately achieved. Because, for the reasons described, the inhomogeneous pore distribution develops slowly over time, the C _x H _y coat formed on the new coating gradually decays, becomes inactive, and subsequently has little or no burn, leading to the disadvantages discussed above. This can be avoided by relying on the inhomogeneous pore distribution not by the described non-reproducible factors but by making the ceramic substrate itself an inhomogeneous structure. This is known in ceramic making (and is not contemplated in the present invention), e.g. dry blending of wind-graded granules in the prescribed ratio and then sintering or after firing with a binder, or possibly providing the required pore structure with fireproof plastic foam profiles. The optimum porosity of the ceramic substrate has been found to be in the 15 to 25 PPI range with a quasi-uniform spatial distribution of pores. When the distribution range is narrower, the adiabatic catalytic post-combustion is not available new dobbetéttel whereby 15 disadvantages resulting from kokszosodásból not is eliminated (this is important when combining more particularly to unleaded gasoline is in use, that is, the noble metal catalyst needs, because in this case the filter now predominantly _C? H _y consists of components and therefore perfect afterburning provides a durable and permanent filter surface for a long service life). If, on the other hand, the distribution range is wider than specified, the presence of smaller pores will result in additional suppression and 20 larger ones will result in a diminishing active filter surface.

The principles of construction of the invention according to the invention are illustrated in the accompanying Figures 1 and 2 to the extent practicable. With these in mind, specific design for a specific engine and drum design is a routine task for 25 professionals.

Figure 1 is a flow diagram illustrating the combination of a multifunctional silencer of the present invention with a preheated auxiliary air controlled catalyst. The exhaust gas from the cylinders enters the tubular section I into the precious metal catalytic converter 2. This is the so-called. by providing precious metals deposited on honeycomb ceramic substrates, it provides NO _x decomposition in the catalyst zone 2a and CO and C _x H _{y in} post-combustion in step 2b. The auxiliary air enters the catalyst zone from the preheater 4 in the gas space 5 between sections 2a and 2b, where it is mixed with the turbulently flowing exhaust gas. The gas flows from the catalyst housing 2 in the tube section 6 to the conventional silencer zone 7 which contains one or two exhaust drums, depending on the particular vehicle type. From there, the gas flows further into the 8-piece silencer end drum according to the invention having the structure shown in Ref. U.S. Pat. Finally, the purified gas is discharged through the exhaust pipe 9 into the open air.

The flowchart 2 illustrates the combination of controlled catalysts without preheated air with the silencer of the present invention. In this version,

However, no additional air is fed into the bane α 2 catalyst housing and the control ensures that the carburate composition is stoichiometric in each mode (λ = 1.00). Therefore, prior to feeding the silencer 8 to the end drum, the diaphragm valve 10 supplies ambient temperature auxiliary air to the flowing gas during each period when the fluctuating pressure of the flowing gas does not reach the outside pressure. The avoidance of preheating is made possible by the fact that when the diaphragm valve 10 is closed, i.e. when the internal pressure is not lower than the external one, the ceramic insert 11 is sufficiently heated by the flowing gas to allow adiabatic catalytic ignition 10 because of its inhomogeneous structure. This structure therefore also eliminates the preheating of the auxiliary air and thus simplifies operation (the honeycomb catalyst support consists of tubes of parallel and uniform cross-section and therefore does not provide an adiabatic effect). After the afterburning of the C _x H _y filtrate in the ceramic insert 11, this ensures that the auxiliary air 15 is heated and that the combustion temperature is maintained. Therefore, the inhomogeneous pore structure of the present invention is also advantageous for promoting adiabatic ignition and post-combustion when used in combination with non-noble metal catalysts (e.g., in vehicles requiring leaded fuel).

Although the present invention and the manner in which it is used will be understood from the foregoing, it will be further illustrated by specific examples of the results.

Options and Variations to Meet the Needs of the Invention

While the multifunctional silencer of the present invention may be used in a number of combinations, they are grouped around three main variants:

1. Non-precious or non-precious-metal-catalytic converters;

2. Regulated noble metal catalytic converter vehicles with replacement air;

3. Regulated noble metal catalytic converters without supplementary air.

Group 1 also includes vehicles 35 that require or can run on leaded petrol. Groups 2 and 3 can only run on unleaded petrol. The following experimental and measurement data represent examples from each of the three groups.

Example: Acoustic and backpressure data for noble metal catalyst-free version

Comparative road acoustic and backpressure tests for the exhaust tailpipe of the DACIA 1300 Combi TX passenger car according to MS 07-4402-1990 and UNECE 59.

s. of the present invention using a Brüel-Kjaer Precision Noise Measuring Instrument 2231 and a Brüel-Kjaer 7005 Measuring Magnetic Recorder with a Brüel-Kjaer Acoustic Verifier. Evaluation was performed using a Brüel-Kjaer 2133 dual-channel frequency analyzer, while the diagrams were made using an HP 7470 / A plotter directly connected to the analyzer. The instruments used for the measurements are in accordance with MSz 11114. they meet the requirements for a precision class of.

The oval drum body had a major axis of 158 mm, a minor axis of 118 mm and a length of 480 mm.

The final result of the measurements was defined, under the same, all prescribed conditions, with the following 15 data.

• Exterior vehicle noise during acceleration with original drum: 77 dB (AF); with insert drum: 77 dB (AF).

· Original drum noise when stationary: 83 dB (AF); with insert drum 78 dB (AF).

Note: For moving vehicles, part of the noise source (tires, tires, wind, road quality) has no influence on the final drum.

Backpressure tests III. speed, with maximum power rpm, open throttle position, off-road hillside.The original drum counter-pressure was 7.5 kPa and the insert drum was 6.8 kPa.

Example: Emission data for the noble metal catalyst-free version

1,992 COROLLA 1600 passenger cars subject to three phase comparative testing according to EPA 75. According to FTP (Federal Test Procedure), the TOC (Total Organic Carbon) ppmC data determined by flame ionization or infrared spectral analysis must be subtracted from the methane (CH4) fraction, as methane ballast is not considered a health hazard component.

The numerical results of the comparative test are shown in the following table (the italicized figures refer to the drum insert according to the invention, which is of the same size as the factory). Δ% represents the relative emission reduction without methane ballast in each phase. The TOC 'ppmC data are the ppm values of C _x H _y carbon content calculated by subtracting the methane content (ppmC data without TOC and CH4 were separately determined as required).

First phase Second phase Third phase TOC ppmC TOC'ppmC TOC ppmC TOC'ppmC TOC ppmC TOC'ppmC 197.5 128.0 92.4 59.1 127.3 86.4 177.0 107.3 87.7 54.2 118.9 70.1 - δ%: 16.2 - δ%: 7.8 - δ%: 18.9

The relative variation in C _x H _y emission attributable to the present invention is apparently small, but it does not reflect the degree of toxicity reduction as the major health-damaging components of the C _x H _y group, including carcinogenic PAH (polyaromatic hydrocarbons) variants, are predominantly filterable. and are present as a filtrate in the post-combustible fraction. Consistent with this, the relative reduction in TOC 10 emissions in phase 2, which best provides steady-state operation, is the smallest, as illustrated in the following example.

Example: Combination with a controlled precious metal catalyst

1992 COROLLA 1600 passenger car undergoes three phase three-phase comparative testing in accordance with EPA 75 standard with a diaphragm valve providing intermittent air intake in front of the drum, as it is equipped with a controlled metal noble metal catalytic converter. The results are summarized in the following table, in italics for the combination according to the invention.

First phase Second phase Third phase TOC ppmC TOC'ppmC TOC ppmC TOC'ppmC TOC ppmC TOC'ppmC 96.0 65.3 1.5 1.1 5.6 3.5 54.6 23.7 1.5 1.1 4.0 1.9 - δ%: 63.7 - δ%: 0 - δ%: 45.7

The relative C _x H _y emission reduction in the first phase is significant and much higher than in the noble metal catalyst version (cf. Example 2), less in the third phase, and in the second phase neither TOC nor TOC 'show difference. This is due to the fact that the cold run phase (120 ± 10 s) is the initial period of the first phase of 512 s and results in significant filterable (including PAH) C _x H _y formation which passes through the noble metal catalyst zone without post-combustion. At the end of the cold run, the noble metal catalyst is activated and, after about 60 seconds, the temperature reaches its optimum efficiency. Therefore, after the second period, the afterburning is almost complete, so there is practically no additional filterable C _x H _y component for the end drum (another issue is that the filtrate afterburner continues in the end drum). The third phase (which is separated from the second by a ten minute cut-off) no longer provides ideal operating conditions for the noble metal catalyst due to partial cooling, and thus the adiabatic catalysis of the present invention is again playing a complementary role to the noble metal catalyst. In this way, a combination of the two catalytic solutions can capture all possible modes of operation that occur in practice.

The additional effect of the multifunctional silencer according to the present invention in terms of meeting the needs is that, while maintaining or sometimes increasing the original function (noise reduction), the C _x H _y filtrate is increased by fresh or safe after-burn incineration provides a lifetime reduction of 15 concentrations of components that are seriously damaging to health. The efficiency of this reduction is the highest in your teacups where the noble metal catalyst is not working or is not working efficiently. This result is of exceptional significance in cold start, cold run, idle and mute modes, such as closed cellar garages, semi-closed parking lots and metropolitan traffic congestion. Not only does this effect of the multifunctional silencer 20 not be disturbed by the lead content of gasoline, but it also allows the extraction of lead in a highly efficient and metallurgically regenerable form. Since noble metal catalysts are not an option when using leaded gasoline, the present invention contributes to reducing health damage in all modes of operation.

Claims (2)

PATENT CLAIMS 1. A concentric, electrolytic-coated, concentric, porous ceramic tubular monolithic silencer end-drum for filtering the exhaust gas of gasoline vehicles, for the metallurgical regeneration of the metal content of the filtrate, or for the post-combustion of combustible components, characterized in that the smallest pores correspond to a pore structure of 10 ± 0.5 and the largest to 6 ± 0.5 pore / cm evenly distributed in space and pore size. Exhaust system fitted with a silencer, characterized in that the regulating range of the λ probe provides an excess air factor between the limits of 1,05 ± 0,03. Silencer end drum according to claim 1, characterized in that a pipe is connected to the exhaust gas line of the vehicle operated without a controlled catalyst, which allows air to flow into the gas when the gas pressure drops.