DE102018123536A1 - Method and device for enabling a reduction in space in a vehicle exhaust system - Google Patents

Abstract

A vehicle exhaust system includes a near-engine end having one or more near-engine exhaust system components that post-treat emissions generated by an engine, and an off-engine end having at least one off-engine component that dampens noise. At least one acoustic volume is located parallel to or in series with the end close to the engine for further noise damping.

Description

BACKGROUND OF THE INVENTION

A vehicle exhaust system directs hot exhaust gases generated by an engine through various exhaust system components to reduce emissions, improve fuel economy, and reduce noise. Newly developed drivetrain technologies are demanding even more stringent noise reduction from the industry. The frequencies to be damped are pushed down to lower and lower values that were not previously considered. A conventional solution for damping such frequencies is to provide a larger internal volume; however, due to the electrification of vehicles, the pressure is growing to reduce the available space for exhaust system components. In addition, continued efforts by the industry to improve fuel economy create further design challenges to reduce the weight of exhaust systems and improve aerodynamics.

These conflicting areas, such as the need for more volume to reduce lower frequencies over the reduced space available for exhaust system components due to the need for space for battery packs, make it clear that there is a need for very particular acoustic solutions that are more efficient from a volume point of view and where the Fuel consumption and engine performance are not adversely affected.

SUMMARY OF THE INVENTION

In one embodiment, a vehicle exhaust system includes a near-engine end having one or more near-engine exhaust system components that post-treat exhaust gases generated by an engine, and a remote end having at least one off-engine component that dampens noise. At least one acoustic volume is located parallel to or in series with the engine near end for noise damping.

In another embodiment, a vehicle exhaust system includes a near-engine end having one or more near-engine exhaust system components that after-treatment exhaust gases generated by an engine, and a remote end having at least one off-engine component that dampens noise, wherein the at least one off-engine component is a valve , a resonance-free tube and / or an active noise reduction. The at least one acoustic volume comprises a parallel or serial volume connected downstream of the engine to the proximal end of the engine.

In another embodiment of any of the above, the near-end end treats exhaust gases and is defined by a first total operating length extending from an engine exhaust to a final exhaust system component that cures exhaust gases and provides the engine remote end with an acoustic treatment and is secondarily exhausted Defines overall operating length that extends from the exhaust system exhaust after-treatment component to an exhaust system outlet at one or more exhaust tailpipes.

In a further embodiment of any of the foregoing, the engine-related components include a three-way catalyst, a selective catalytic reduction catalyst, an oxidation catalyst and / or a particulate filter.

In a further embodiment of any of the foregoing, the at least one off-engine component comprises only the non-resonant tube and a valve.

In a further embodiment of any of the foregoing, the at least one off-engine component comprises only one valve.

In a further embodiment of one of the above, the at least one acoustic volume in the end close to the engine comprises at least two acoustic volumes in the end close to the engine.

In a further embodiment of any of the foregoing, the at least one off-engine component comprises only the active noise reduction, and wherein the at least one acoustic volume in the engine-proximate end comprises at least two acoustic volumes in the engine-proximate end.

In another embodiment, a method of providing a reduced volume exhaust system includes the steps of: providing a proximal end having one or more near engine exhaust system components that after-treatment exhaust gases generated by an engine; Providing an engine remote end having at least one off-engine component that dampens noise, the at least one off-engine component comprising a valve, a non-resonant pipe and / or an active noise reduction; and providing at least one acoustic volume in parallel with or in series with the engine near end for silencing in combination with the at least one off-engine component to provide one or more exhaust mufflers remote from the engine and / or To eliminate reflection muffler and to reduce a total length of the motor remote end.

These and other features of this application are best understood from the following description and drawings, which are briefly described below.

list of figures

• 1 schematically illustrates a vehicle exhaust system and shows standing pressure waves generated by the system.
• 2 shows an example of a close-coupled component of the system 1 with the present invention.
• 3 shows a further embodiment.
• 4 shows a further embodiment.
• 5A shows a further embodiment.
• 5B shows a further embodiment.
• 5C shows a further embodiment.
• 6A shows a further embodiment.
• 6B shows a further embodiment.
• 6C shows a further embodiment.
• 7 shows a further embodiment.
• 8th is a schematic representation of an example of an exhaust system in a compact design with an acoustic volume in the engine near end.
• 9 is another example of an exhaust system in a compact design with an acoustic volume in the engine near end.
• 10 is another example of an exhaust system in a compact design with an acoustic volume in the engine near end.

DETAILED DESCRIPTION

In 1 is a schematic representation of a vehicle exhaust system 10 shown as a long pipe by a motor 12 produced hot exhaust gases for emission reduction and noise reduction in a known manner by various exhaust system components passes. The various exhaust system components may include one or more of the following: pipes, filters, valves, catalysts, mufflers, etc. The exhaust system 10 has a near-motor end 14 located just downstream of the engine 12 is located, and a motor remote end 16 on, which is located downstream of the end near the motor 14 located. The long tube is considered to be at the end of a motor 18 closed and at an opposite end 20 opened at which the engine exhaust after passing through the various exhaust system components from the exhaust system 10 escapes into the atmosphere.

The engine near end 14 includes a section of the exhaust system 10 having after-treatment components. To exhaust system components at the end close to the engine 14 For example, exhaust gas treatment elements such as a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a gasoline particulate filter (GPF), a three-way catalyst (TWC) and a selective catalyst may be used catalytic reduction (SCR catalyst), which serve to remove pollutants in a known manner from the exhaust gas. The engine near end 14 extends from an engine outlet, eg, an exhaust manifold or turbocharger, through the aftertreatment components and ends immediately after the last aftertreatment element. Exhaust gases flow through these components close to the engine and reach the far end of the engine 16 where the exhaust gas through an exhaust system outlet via one or more exhaust pipes from the plant 10 exit. The motor remote end 16 includes a section of the exhaust system 10 Located downstream of the aftertreatment elements and components for acoustic treatment of the exhaust system 10 having. The motor remote end 16 may include components such as exhaust mufflers, reflection mufflers, pipes, valves and one or more tailpipes. The motor remote end 16 extends from the last aftertreatment component through the acoustic components and terminates at the outlet from one or more tailpipes. The close-up section 14 and the motor remote section 16 are usually connected to each other via a flange connection. The engine near end 14 thus includes aftertreatment / emission components, while the engine remote end 16 includes acoustic components. The exhaust system components described may be mounted in very different designs and combinations depending on the vehicle application and available space.

worin:

• fn = Resonanzfrequenz der stehenden Welle n (Hz)
• n = Ordnungszahl der stehenden Welle
• c = Schallgeschwindigkeit (m/s)
• L = Länge des geschlossenen-offenen Rohres (m)

As explained above, in 1 the exhaust system shown schematically as a long tube shown at the engine end 18 closed and at the opposite end 20 open to the atmosphere. Sound waves move from their source, which is the engine 12 act through the pipe and then exit to the atmosphere. If the sound wave strikes a boundary of some kind, such as a change in impedance, then a portion of the wave will be reflected back on the way it came, and the remainder will continue. For a closed-open tube, as in 1 is shown, this reflection occurs at the exit of the tube. The reflected wave overlays the incident wave, and at certain frequencies, which are dependent on the length of the tube, they constructively overlap so that the level of the wave increases and this also makes the wave appear stationary. Such waves are referred to as standing waves, and in a closed-open tube, the frequencies of such waves can be calculated using the equation below. $$\text{Fn}=\left(\text{nc}\right)\text{/}\left(\text{4L}\right).$$

wherein:

• fn = resonance frequency of the standing wave n (Hz)
• n = ordinal number of the standing wave
• c = speed of sound (m / s)
• L = length of the closed-open tube (m)

The diagram of 1 shows the first three standing pressure waves for a closed-open pipe 4 meters long. In this example, the resonances occur at 22, 65 and 108 Hz. As shown, the pressure at each standing wave is at the closed engine end 18 maximum (antinode) and at the open end 20 minimal to the atmosphere (knots). The ideal place for a Helmholtz resonator is on a pressure-swinging belly. Therefore, the best position is for a resonator at the motor output; However, Helmholtz resonators are conventionally not in the motor near end 14 of exhaust systems 10 used. In the present invention, a Helmholtz resonator is in the near-end 14 provided an improved acoustic benefit over the same resonator as in the motor remote end 16 arranged to provide since the present resonator is closer to the antinode at all acoustic resonances of the system.

Tests and simulations have shown that a Helmholtz resonator, such as an acoustic volume of about 2 to 4 I connected to the exhaust flow via a neck tube, is near the engine end 14 is arranged between a turbo outlet and a catalyst or between catalyst aftertreatment elements, provides an acoustic benefit that is about twice as large as that of a similar volume amount, that in the motor remote end 16 (downstream of the aftertreatment) is applied without this having an effect on the back pressure. From the point of view of exhaust tailpipe noise, the positioning of the Helmholtz resonator offers as close as possible to the engine 12 the best acoustic performance.

In the present invention, it is proposed to use one or more Helmholtz resonators at one or more locations near the engine 14 the plant 10 install. For example, the resonator (s) could be positioned behind the manifold or turbo outlet, but before the catalysts, between the catalysts and / or behind the catalysts. Various exemplary embodiments are explained below and shown in the attached figures.

In 2 is an example of a close-coupled component 30 shown, which is located downstream of the exhaust manifold and the turbocharger. The engine-related component 30 has a component housing 32 on, that has an interior cavity 34 forms. A first exhaust treatment element 36 is in the inner cavity 34 arranged, and a second exhaust treatment element 38 is downstream and across a gap 40 from the first exhaust treatment element 36 axially spaced in the internal cavity 34 arranged. One in a resonator housing 43 enclosed resonator volume 42 stands with the inner cavity 34 in connection. The resonator housing 43 surrounds the component housing 32 at least partially.

An inlet cone 44 directs a flow into the first exhaust treatment element 36 , The inlet cone 44 Receives hot engine exhaust gases from an intake pipe 46 , An outlet cone 48 conducts a stream of treated exhaust gases from the second exhaust treatment element 38 exit, into an outlet pipe 50 , In this example, the component housing defines 32 a central axis A , and the inlet cone 44 , the first exhaust treatment element 36 , the second exhaust treatment element 38 and the outlet cone 48 are coaxial with the central axis A ,

At least one resonator connection 52 stands with the resonator volume 42 in the resonator housing 43 in connection. The resonator housing 43 includes a middle housing portion 54 containing the first and the second gas treatment element 36 . 38 encloses an inlet section 56 at one end of the middle housing section 54 positioned so that it is the inlet cone 44 surrounds, and an outlet section 58 at the opposite end of the middle housing section 54 is positioned so that he has the outlet cone 48 surrounds. At least one resonator connection 52 stands with the resonator volume 42 in connection. At the in 2 In the example shown, the resonator connection comprises 52 a Helmholtz neck, the gap 40 is positioned and with the Helmholtz resonator volume 42 communicates. Optionally or additionally, the connection point of the resonator connection could 52 at the inlet cone 44 or at the outlet cone 48 are as in 2 indicated by dashed lines.

In each of these different embodiments, the design is sealed so that there is no net flux in the Helmholtz resonator. Hot engine exhaust flows through the inlet pipe 46 one, expands and slows down while the gas is the intake cone 44 flows through, the first exhaust gas treatment element 36 go through and then into the gap 40 between the first and second exhaust treatment elements 36 . 48 expands. The Helmholtz resonator connection 52 and the resonator volume 42 lie at the gap 40 connected parallel to the flow. The exhaust gas then contracts and flows through the second exhaust treatment element 38 and then expands into the outlet cone 48 out before it contracts and through the outlet tube 50 exit.

The exhaust gas pressure pulsations from the engine pass through the exhaust system 10 and are modified as they undergo the mechanisms of constriction, reflection and absorption. When the pulsations the gap 40 cause they cause the exhaust gas in the resonator neck / port 52 is set in motion. At low frequencies, this gas can be considered point mass. The point mass of gas in the resonator neck 52 The exhaust gas compresses or dilutes in the surrounding resonator volume 42 , When the point mass of gas is the resonator volume 42 compressed, the volume pressure increases. With dilution of the point mass of gas, the volume pressure decreases. As a result of this pressure, the spot mass is forced in the opposite direction to that in which it moves. Thus, the resonator volume acts 42 as a spring and provides a spring-mass system with tuned frequency. Since there is no net flow through the Helmholtz resonator and the resonator neck 52 a side branch arrangement, the effects on the back pressure are negligible.

At the in 2 The example shown is the resonator volume 42 between an inner surface of the resonator housing 43 and an outer surface of the component housing 32 educated. The resonator volume 42 is concentric to the central axis A , such that the resonator housing 43 and the resonator volume 42 an outer periphery of the first and second gas treatment elements 36 . 38 completely and completely surrounded. In 3 an example is shown that out 2 is similar, but includes a staggered version. In this example, the resonator volume is 42 ' opposite the component housing 32 so offset that the resonator housing 43 and the resonator volume 42 ' an outer periphery of the first and second gas treatment elements 36 . 38 only partially surrounded.

In 4 another embodiment is shown. In this example, a resonator volume 60 from the component 30 removed and over at least one pipe 62 to the component housing 32 connected. The resonator volume 60 is in a resonator housing 64 enclosed and the pipe 62 connects the resonator housing 64 with the component 30 , Thus, there are the resonator housing 64 and the volume 60 outside the component housing 32 ,

In one example, the resonator housing includes 64 one or more additional components. In another example, an existing vehicle structure serves to provide the sealed volume, see, for example, Application No. 15 / 874,288, which is assigned to the assignee of the present application and hereby incorporated by reference. In one disclosed example, a vehicle frame member provides a closed resonator volume 60 ready, which is connected in parallel with the exhaust system flow.

At the in 4 shown example connects the tube 62 the resonator housing 64 with the inlet section 44 of the component housing 32 , The pipe 62 is also optional on the outlet section 48 connected; the inlet section 44 However, it is preferred because it is closer to the engine 12 is located. Optionally or additionally, an additional pipe or branch could be from the pipe 62 the volume 60 with the middle housing portion and the inlet portion 44 or the outlet section 48 connect.

In 5A an example is shown where the external volume 60 to the inlet pipe 46 connected. In 5B an example is shown where the external volume 60 connected to the middle housing section and with the gap 40 communicates. In 5C an example is shown where the external volume 60 to the outlet pipe 50 connected.

In the 6A-6C are examples of an internal resonator volume 70 shown in series with the first and second exhaust treatment elements 36 . 38 lies. In 6A an example is shown where the volume 70 upstream of the first exhaust treatment element 36 is located. In 6B an example is shown where the volume 70 upstream of the second exhaust treatment element 38 and downstream of the gap 40 is located. In 6C an example is shown where the volume 70 downstream of the second exhaust treatment element 38 is located.

At another, in 7 the example shown are the first and the second gas treatment element 36 . 38 in a common housing 80 built-in. In this embodiment, the first and second exhaust treatment elements 36 . 38 not coaxial and parallel to each other and across a gap 82 connected so that exhaust gas from the first exhaust treatment element 36 exit, into the gap 82 enters and then into the second exhaust treatment element 38 entry. In the case 80 are several resonator volumes 84 intended. Also, several resonator connections 86 intended. The housing 80 has a baffle 88 on, wherein an inlet resonator volume 90 with an inlet pipe 92 coupled and an outlet resonator volume 94 with an outlet pipe 96 is coupled. The housing 80 also has a second baffle 98 to form a resonator volume at the gap 82 on.

Possible positions for the resonator connections 86 are at the inlet resonator volume 90 , at the outlet resonator volume 94 and at the resonator volume at the gap 82 , The one at the gap 82 associated resonator connection 86 can be at one point between the elements 36 . 38 at an exit from the first exhaust treatment element 36 and / or at an input to the second exhaust treatment element 38 be located. The resonator connections 86 can be used to achieve the desired acoustic effect as needed in any number and in any combination.

In each of these different parallel embodiments, the interior acoustic volume is closed and parallel to the exhaust gas flow through the exhaust system such that there is no net flow in the Helmholtz resonator. Hot engine exhaust gas flows through the inlet tube into the component, expands and slows as the gas passes through the inlet cone, flows through the exhaust treatment element, then contracts and passes through the outlet cone before exiting into the outlet tube. The neck switches the internal acoustic volume parallel to the flow through the component to provide the Helmholtz resonator.

Thus, a tuning element with the main function of silencing with a component near the engine end 14 the exhaust system 10 combined in a location that is much closer to the pressure swing at the engine exhaust outlet than in conventional designs. This provides improved acoustic efficiency with negligible backpressure effects, leading to improvements in exhaust tailpipe noise / volume. Furthermore, space problems are significantly reduced by the inclusion of an acoustic volume in the existing engine auxiliary frame structure.

In the 8th to 10 are examples of exhaust systems 10 shown where one or more acoustic volumes 100 in the engine near end 14 in combination with at least one noise damping component 102 in the motor remote end 16 be used, so that a design with reduced space is provided. The motor remote end 16 the exhaust system 10 For example, there are exhaust mufflers, valves, reflection mufflers and exhaust pipes, etc. that have conventionally been used in various noise reduction designs. To components close to the engine 104 For example, a three-way catalyst, a selective catalytic reduction catalyst, an oxidation catalyst, a diesel or gasoline particulate filter, etc., are variously used to reduce emissions. The at least one noise damping component 102 For example, it includes a valve 102 , a resonance-free tube 102b and / or a system for active noise reduction 102c , In the present invention, the combination of the noise damping component 102 in the motor remote end 14 and at least one acoustic volume 100 in the engine near end 14 used to eliminate conventional off-engine components such as reflection mufflers and exhaust mufflers, what the amount of from the exhaust system 10 occupied area significantly reduced.

The valve 102 For example, it may be a passive valve with a valve flap that is resiliently biased to a closed position and whose movement is controlled only by changes in exhaust pressure within the flow path. The valve 102 could also be an actively controlled valve in which the movement of a valve flap is controlled by an actuator and control system. Optionally, the valve 102 a combination of a passive and an actively controlled valve.

The resonance-free pipe (RFP (free pipe)) 102b For example, may have one or more vent holes that serve to reduce noise. In one example, the vent holes are located at predetermined locations along a length of the tube to reduce resonant frequency noise. The vent holes may be covered with a mesh or micro-perforated material to further reduce noise as needed.

The Active Noise Cancellation System (ANC) 102c includes a control unit C , a microphone M and a speaker S For damping / suppression of noise in the motor remote end 16 the exhaust system 10 work in a known manner.

In 8th an example is shown in which the number of components of the motor remote end 16 is significantly reduced compared to conventional exhaust system designs. The motor 12 passes hot exhaust gases through pipes 106 and the components close to the engine 104 the near-motor end 14 in pipes 108 in the motor remote end 16 , In this example, the engine near end 14 an acoustic volume 100 on, with only one valve 102 and a resonance-free tube 102b in the motor remote end 16 is used. The valve 102 is located in a tube remote from the engine 108 upstream of the non-resonant tube 102b , The resonance-free tube 102b For example, one or more vent holes 110 have, in conjunction with the valve 102 work to dampen noise to desired levels. No other exhaust silencers or reflection silencers are in the engine remote end 16 required for noise reduction. This will be the length of the motor remote end 16 significantly reduced compared to conventional designs.

In 9 an example is shown in which the close to the engine end 14 two acoustic volumes 100 that has only one valve 102 in the motor remote end 16 be used. In this example, the valve is 102 at an upstream end of the engine distal end 16 arranged. This example provides an even shorter length for the far end of the engine 16 ,

In 10 an example is shown in which the close to the engine end 14 two acoustic volumes 100 that only works with the system for active noise reduction 102c in the motor remote end 16 be used. This example provides an even shorter length for the far end of the engine 16 than that 9 , This embodiment also has a very minimal back pressure.

As with any of the examples of 8th to 10 is shown is the motor end 14 by a first total operating length L1 and the motor remote end 16 by a second total operating length L2 Are defined. In one example, there is a ratio of the first total operating length L1 to the second total operating length L2 depending on a length of the vehicle and a scope of aftertreatment in a range of 1: 2 to 1: 4. The or the near-engine acoustic volume (s) 100 are upstream of the last substrate element of the near-end 14 located and the gas flow is parallel to the acoustic volume 100 , By the use of the or near the engine acoustic volume or volumes 100 in combination with a valve 102 , a resonance-free tube (RFP) 102b and / or an active noise reduction system (ANC) 102c in the motor remote end 16 the amount of space reduction is maximized.

While one embodiment of this invention has been disclosed, one of ordinary skill in the art appreciates that certain modifications are within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims (20)

Vehicle exhaust system with: a near-engine end having one or more near-engine exhaust system components that post-treat emissions generated by an engine, a motor remote end having at least one remote engine component that dampens noise, and at least one acoustic volume that is parallel to or in series with the engine near end for noise damping. Vehicle exhaust system after Claim 1 in which the engine-related components include a three-way catalyst, a catalyst with selective catalytic reduction, an oxidation catalyst and / or a particulate filter. Vehicle exhaust system after Claim 2 in which the at least one acoustic volume is arranged parallel to the exhaust gas flow and comprises an airtight and closed cavity. Vehicle exhaust system after Claim 2 or 3 in which the at least one acoustic volume is arranged parallel to the exhaust gas stream and is located in a catalyst or filter housing. Vehicle exhaust system according to one of Claims 2 to 4 in which the at least one acoustic volume is arranged parallel to the exhaust gas flow and is located within a vehicle frame component. Vehicle exhaust system according to one of Claims 2 to 5 in which the at least one component remote from the engine comprises a valve, a resonance-free tube and / or an active noise reduction. Vehicle exhaust system after Claim 6 in which the at least one component remote from the engine comprises only one valve. Vehicle exhaust system after Claim 7 in which the at least one component remote from the engine additionally comprises the resonance-free tube. Vehicle exhaust system after Claim 7 or 8th in which the at least one acoustic volume in the near the engine end comprises at least two acoustic volumes in the engine near end. Vehicle exhaust system according to one of Claims 6 to 9 in which the at least one component remote from the engine comprises only the active noise reduction and in which the at least one acoustic volume in the end close to the engine comprises at least two acoustic volumes in the end close to the engine. A vehicle exhaust system according to any one of the preceding claims, wherein the engine near end is exhaust treated and defined by a first overall operating length extending from an engine exhaust to a final exhaust system component, the exhaust aftertreated, and the engine remote end provides acoustic treatment and a second overall operating length which extends from the exhaust system exhaust after-treatment component to an exhaust system outlet at one or more exhaust tailpipes. Vehicle exhaust system with: a near-engine end having one or more near-engine exhaust system components that post-treat emissions generated by an engine, a motor remote end having at least one remote engine component that dampens noise, wherein the at least one engine remote component comprises a valve, a resonance-free tube and / or an active noise reduction, and at least one acoustic volume in the engine-near end for noise damping, wherein the at least one acoustic volume comprises a parallel or serial volume, which is connected downstream of the motor with the motor-proximate end. Vehicle exhaust system after Claim 12 in that the near-end end is exhaust aftertreated and defined by a first total operating length extending from an engine exhaust to a final exhaust system component, the exhaust aftertreated, and the engine remote end provides acoustic treatment defined by a second total operating length different from the final exhaust system component that post-processes exhaust gases to an exhaust system outlet at one or more exhaust tailpipes. Vehicle exhaust system after Claim 13 in which the engine-related components include a three-way catalyst, a catalyst with selective catalytic reduction, an oxidation catalyst and / or a particulate filter. Vehicle exhaust system after Claim 14 in which the at least one acoustic volume is located within a catalytic converter housing, a filter housing and / or a vehicle frame element. Vehicle exhaust system after Claim 15 in which the at least one component remote from the engine comprises only the resonance-free tube and a valve. Vehicle exhaust system after Claim 15 or 16 in which the at least one component remote from the engine comprises only one valve. Vehicle exhaust system after Claim 17 in which the at least one acoustic volume in the end close to the engine comprises at least two acoustic volumes in the end close to the engine. Vehicle exhaust system according to one of Claims 15 to 18 in which the at least one component remote from the engine comprises only the active noise reduction and in which the at least one acoustic volume in the end close to the engine comprises at least two acoustic volumes in the end close to the engine. A method of providing a reduced volume exhaust system comprising: Providing a near-engine end having one or more engine-related exhaust system components that after-treatment exhaust gases generated by an engine; Providing an engine remote end having at least one off-engine component that dampens noise, the at least one off-engine component comprising a valve, a non-resonant pipe and / or an active noise reduction; and Providing at least one acoustic volume in parallel with or in series with the engine near end for silencing in combination with the at least one off-engine component to eliminate one or more off-axis exhaust mufflers and / or reflection mufflers and reduce an overall length of the remote end.

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