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Technology portfoliofor the Original Equipment (OE) market

Standalone Diesel Emissions Aftertreatmentfor Commercial Vehicles, Mobile Machinery

and Stationary Applications

Standalone diesel emissions aftertreatment ................................................................................................... 3

Technical solution: System overview .......................................................................................................... 4 - 5

Thermal management: Hydro Carbon Injection (HCI) ...................................................................................... 6

Thermal management: Catalytic Bypass Burner (CB2) ..................................................................................... 7

Denox: Selective Catalytic Reduction (SCR) ..................................................................................................... 8

Denox: System variants ................................................................................................................................... 9

Control and monitoring: Functions and components ..................................................................................... 10

Innovative diesel emissions aftertreatment ................................................................................................... 11

Development expertise: Tools and methods .................................................................................................. 12

Development expertise: Control and software .............................................................................................. 13

Development expertise: Applications ............................................................................................................ 14

Development expertise: Acoustics ................................................................................................................. 15

Contents

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© HJS Emission Technology GmbH & Co. KG, 58706 Menden/Sauerland, Germany

All information and data stated in this Product Range document has been compiled with utmost care. Nevertheless, HJS accepts no liability for any errors, omissions or other inaccuracies contained herein. Subject to change without notice. Reprinting or reproduction, in whole or in part, including of photographs, illustrations or graphics, is not permitted without the prior written consent of HJS Emission Technology.

We reserve all rights in connection with this document.

The vehicle applications cited in this Product Range document may possibly be valid only up to the date printed on the last page of the document. All references made in this Product Range document to the item numbers of vehicle manufacturers and/or competitors are provided for the purpose of comparison only. Such information is not allowed to be used in invoices issued to vehicle owners.

Whether they're installed in heavy-duty trucks, buses, forklift trucks,bulldozers or district heating plants, diesel engines often have a reallytough job to perform. And thanks to their outstanding performance,reliability and efficiency, they excel in their job. But there's anothercharacteristic that's becoming ever more important: if the quality ofthe air we breathe is to improve, vehicles and mobile machines haveto be environment-friendly, too.

To achieve this goal, legislators have laid down binding limit valuesfor exhaust emissions, limits that will be tightened up even furtherover the coming years. In particular, the authorities are targeting aneffective and long-term reduction in particulate matter (PM) and nitrogen oxide emissions.

The limits enforced to date in the non-road segment have mostly beenable to be complied with by optimising the set-up of the engine on thebasis of low-emission internal combustion. In their efforts to achievethis, vehicle and engine developers are essentially confronted withthe contradiction that a low-emission combustion process also hasthe unfortunate side-effect of increasing fuel consumption. By investing substantial technical expertise and effort, manufacturershave so far succeeded in preventing a noticeable increase in consumption and avoiding the use of external exhaust-gas aftertreatment. But the increasing tightening of emissions limits is intensifying the conflict between reducing particulate and nitrogenoxide emissions on the one hand and developing drive systems thatare as economical as possible on the other.

The task of developing drive systems that are both as economicaland as clean as possible will be an even greater challenge in future.2014 will see the coming into force of even more stringent limits applicable to heavy-duty commercial vehicles, such as trucks andbuses, with the enactment of the Euro VI emissions standard. In theUSA, too, commercial vehicles are now, since the introduction of theEPA 2010 standard, already forbidden from emitting virtually anyparticulates and nitrogen oxides.

The situation is similar in the non-road sector, too, after 2011 sawimplementation of Stage IIIB of the European Union's emissions directive and the Tier 4 interim emissions requirements in the USA.In 2014, these will be followed by Stage IV and Tier 4 final, respectively.

In most cases, the ever more stringent legal requirements can only bemet with the aid of additional exhaust-gas aftertreatment with effective, low-maintenance, heavy-duty and long-life emissions reduction systems. The contradiction between fuel consumption andemissions reduction can to a large extent be solved, and the latitudegained offers scope for outright optimisation of engines' fuel efficiency and consequently for the associated optimisation of theCO2 emissions of commercial vehicles and mobile machinery.

Standalone diesel emissions aftertreatment for commercial vehicles, mobile machinery and stationary applications

Complying with future emissions standards Global tightening of emissions limits

Development emission limits for Non-Road applications (EU/US) Development emission limits for On-Road applications (EU)

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Technical solution: System overview

In addition to stipulating the reduction of carbon monoxide (CO) andhydrocarbons (HC) emissions, existing and future emissions regulations above all target lower PM and nitrogen oxide (NOx) emissions. Whereas CO and HC are oxidised in a catalytic converterto form the harmless substance water (H2O) and carbon dioxide(CO2), particulates have to be trapped by a filter and nitrogen oxidestransformed into nitrogen (N2) and water by adding urea and deploying a second catalytic converter.

This complex exhaust treatment process can be divided up into twosubsystems:

1. Diesel oxidation catalyst (DOC) and particulate filter forreducing HC, CO and particulate matter

2. Denox system for reducing NOx in the exhaust gases

Combined particulate and nitrogen oxide reduction Particulate filtration and regeneration

Diesel particulate filters are installed in order to comply with the statutory emissions limits and therefore to reduce the level of particulate matter (PM) in the exhaust gases. They are available in various sizes and materials – such as sintered metal, cordierite or silicon carbide. The degree of efficiency of what are known as '100%filter systems' is indeed as high as 100 per cent with respect to thenumber of particulates. The exhaust gases from the engine – whichcontain soot particles – are fed into the filter housing and through thefilter substrate. The gaseous components of the exhausts flowthrough the microscopic pores of the filter material; the soot particles,including the ultra-fine particles, are trapped and deposited on the individual filter pockets.

To prevent the backpressure in the exhaust system from increasingabove the value specified by the engine manufacturer, the systemshave to be regularly cleared of soot (PM) by means of oxidation. This

System overview: Standalone diesel emissions aftertreatment

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Many commercial vehicle applications, mobile machines and stationary applications have load profiles that, owing to the low exhaust-gas temperatures, necessitate the use of active thermal management processes in order to guarantee full functional reliability of the diesel emissions aftertreatment system. This appliesto regeneration of the particulate filter and to denox systems alike.

Active thermal management can be conducted by means of enginemodifications. However, in the case of many commercial vehicle andnon-road applications, thermal management is frequently implemented by means of post-engine measures, i.e. exhaust-gas aftertreatment, owing to the demands for efficiency, long servicing intervals and a long service life. Established methods in use today include burner-based systems, systems for hydrocarbon (HC, i.e. fuel)dosing downstream of the engine, downstream HC conversion in acatalytic converter or a combination of the latter two.

Active thermal management strategies

process is called 'regeneration'. This regeneration of a particulate filter, with the aid of oxygen, requires high exhaust-gas temperaturesof at least 550°C, which, however, diesel engines relatively seldomreach (it depends on the pattern of use and performance requirements). This particularly applies to municipal utility vehicles,distribution vehicles (such as post office vehicles) and most non-roadmobile machines. For such vehicles and machinery, passive systems– which are based solely on the CRT (Continuously RegeneratingTrap) effect and only oxidise PM with the aid of NO2 within a limited temperature window – are for the most part unsuitable. Instead, active thermal management strategies are employed forsuch applications.

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Thermal management: Hydro Carbon Injection (HCI)

Active thermal management methods are required to achieve reliableregeneration of the particulate filter under all operating conditions.Common to these methods is the deliberate and automatic triggering ofregeneration by means of an active increase in the exhaust-gas temperature to a level of approx. 600°C. When additives that lower theignition temperature of particulate matter are used (what are known as"fuel-borne catalysts", or FBCs for short), the exhaust-gas temperatureneeds only be raised to between 350 and 400°C. However, it's frequentlythe case that additives cannot be used because the engine or injection-system manufacturer has not approved them. One method that is alreadybeing employed as standard is the injection of fuel downstream of the

engine. This fuel is converted (with heat release) to CO2 and H2O in adiesel oxidation catalyst (DOC) installed in the exhaust-gas system, a unitalso known as a "catalytic burner". The burner generates enough heatthat the temperature of the exhaust gases rises to the required level.

One criterion that does have to be met when employing this method,however, is that the exhaust gases from the engine already have a sufficiently high temperature to enable the reaction in the DOC to actuallytake place. Below this "light-off temperature", the catalytic converterfunctions to such a minimal degree that it's not capable of converting thefuel injected.

Technical specifications: HC doser

• Dosing volume up to max. 16 kg/h (mid-flow) or 30 kg/h(high-flow), infinitely variable control (~180 kW; ~360 kW)

• Atomisation without compressed air• Mean droplet diameter approx. 80 µm• Additional safety valve for cutting fuel supply• Water-cooled, active dosing valve immediately in exhaust

system

System overview: HCI

HCI: temperature curve during active regeneration

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Technical specifications• Burner type: two-stage catalytic burner• Burner capacity: starts at 5 kW, infinitely variable control• Electrothermal preheating possible• 12 V or 24 V power supply• Can be used for engines with rated power output of up to 560 kW• No external air supply necessary• Thermal load on materials low thanks to exhaust-gas

temperatures < 700°C

How it works• Dividing of the exhaust mass flow between a primary and a

bypass flow pipe by means of an exhaust flap• Electrothermal exhaust-gas preheating • Electrical energy only required in the start phase; afterwards heat is developed purely through catalytic effect

• Fuel dosing by means of a HC doser • Catalytic conversion of the fuel in the pre-DOC• Fuel slip at the pre-DOC to supply the primary DOC• Mixing of exhaust gases from the primary and bypass flows• Catalytic conversion of the fuel in the primary DOC• Control of fuel dosing until the required system temperature

is reached

Thermal management: Catalytic Bypass Burner (CB2)

In the case of two-stage, electrothermically assisted HC conversion, abypass flow is tapped off from the exhaust mass flow downstream ofthe turbocharger. It's into this bypass flow pipe that HC dosing is conducted for the entire system, the system comprising two diesel oxidation catalysts (DOCs). Part of the fuel injected is converted in thefirst DOC (pre-DOC), so that the exhaust gases in the bypass flowdownstream are already heavily enriched with hydrocarbons and havereached temperatures of more than 600°C.

These gases then mix with the cooler exhaust gases from the primaryflow, upstream of the second DOC (primary DOC). By feeding the hotgases from the bypass flow into the primary flow, the system ensuresthat the temperature of the overall exhaust-gas flow immediatelyupstream of the primary DOC is always higher than its light-off temperature. This in turn ensures that the particulate filter can be regenerated under all engine operating conditions.

If the exhaust-gas temperature in the system is below the light-off temperatures of both the primary DOC and the pre-DOC, it is possibleto use a heating element to increase the temperature of the exhaustgases in the bypass flow to such an extent that the light-off temperature is actually reached in the pre-DOC. In this way, the systemcan be made to function reliably even if the exhaust temperaturesreached normally are low.

The exhaust flap installed in the primary exhaust flow controls thesystem by distributing the volume flows, while taking into account theboundary conditions, ensuring the pre-DOC operates reliably throughout a long service life. Thanks to its good cold-starting characteristics, this system is highly suitable for all types of thermalmanagement. Even if exhaust-gas temperatures are extremely low, it'scapable of raising them to such a level that the start temperaturesrequired by downstream exhaust-gas aftertreatment systems for handling gaseous pollutants (CO, HC, NOx) are reached.

Thermal management by means of two-stage, electrothermically assisted HC conversion

Two-stage burner: temperature curve during active regeneration

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DENOX: Selective Catalytic Reduction (SCR)

In addition to particulate matter, nitrogen oxides are the second mainexhaust-gas component whose level needs to be reduced in order tocomply with the statutory regulations. Current and future emissionsdirective for the on- and non-road sector stipulate extremely low limits for nitrogen oxide emissions. These limits can be met with theuse of nitrogen oxide reduction systems (DENOX).

The characteristics of urea and the temperature-dependent reactionin the catalytic converter mean that the exhaust gases must have atemperature of approximately 200°C if the injection of an aqueousurea solution (marketed under the brand name AdBlue®) is to be effective. Furthermore, the process also requires that the urea is hydrolysed to as full an extent as possible and that the solution is uni-formly distributed over the entire cross-section of the pipe upstreamof the SCR catalytic converter (γ > 0.93). This assumes that the injection nozzle is correctly positioned and the hydrolysis section issufficiently long. If the amount of installation space available doesn'tallow this equipment to be installed, it's possible to install either amixer as a secondary vaporiser or a hydrolysis catalytic converter.

Optimisation of how the fluid flow is guided is supported in the design phase by means of a two-phase 3D CFD calculation. In theapplication illustrated, the uniformity of ammonia distribution up-stream of the SCR catalytic converter is greatly improved by selectedmeasures. Unlike the case with on-road commercial vehicles, non-road mobile machinery and stationary applications are not equippedwith a compressed-air system, so the urea (AdBlue®) injection systems used must function without compressed air. The resultingnegative effect on the size and distribution of the droplets meansthat it's even more important how the urea solution is prepared (by

the mixer, hydrolysis cat). Different SCR catalytic converter techno-logies can be employed depending on the application. If an actively regenerating filter system is installed, the temperature downstreamof the filter can rise to levels in excess of 650°C. In such cases, SCRcatalytic converters that use Fe- or Cu-zeolites as the active substancecan be recommended, because these minerals are highly stable athigh temperatures.

Due to the fact that urea (AdBlue®) freezes at a temperature of just -11°C, the legal requirements in respect of the operability of the tankand line heating system at low temperatures must be complied witheither by fitting an electrical heating system or by running lines fromthe engine cooling system via the urea tank and pipes. The parame-ters required to calculate the amount of fuel to be injected, such asthe exhaust-gas temperature, NOX concentration and exhaust massflow, can be determined by means of a CAN bus, analogue sensorsor emission models. A second NOX sensor can be installed down-stream of the system in order to monitor operation (OBD purposes)and possibly to make adjustments. The control system is equippedwith complex activity and storage models, which guarantee a highlevel of NOX conversion rates with minimal NH3 slip.

As an option, it is also possible to use an ammonia slip-catalyst toprevent an ammonia breakthrough: the catalytic converter is equip-ped with a precious metal coating that, in a controlled manner, oxi-dises ammonia to form nitrogen. If active thermal managementmethods (e.g. Burner, HCI) are installed upstream in the system, thesecan also manage the temperature of the SCR system in cold-startphases.

Uniformity of ammonia distribution before optimisation Uniformity of ammonia distribution after optimisation

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Denox: System variants

Technical specifications Dosing unit:

• Operating range of pumps:0,04 – 7 l/h

• IP rating:IP69K

• Power supply:12 V and 24 V

• Ambient temperature ofpumps:- 40°C – +85°C

• Nozzle:cooled variants

SCRT® System

SCR System

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Control and monitoring: Functions and components

The control unit controls and monitors all functions and active com-ponents of the exhaust-gas aftertreatment system, such as the heating element, the exhaust flap and the dosing systems. The software that goes with it covers the control strategies required tocomply with the respective emissions targets. No changes are madeto the engine management system.

The data required for control purposes are transferred from the engine to the exhaust-gas aftertreatment control unit by means of aCAN interface. Sensors pick up readings for the temperature, pressureand the nitrogen oxide content in the exhaust gases. The control unitthen uses these data to coordinate the actuators of the system as required, with the assistance of the operating strategy laid down inthe software.

The operating strategy comprises two core components – particulate filter regeneration and the AdBlue® dosing strategy forNOx reduction – and ensures that the emissions limits laid down arecomplied with. What's more, an on-board diagnosis system (OBD)monitors those components and assemblies of the exhaust-gas aftertreatment system that are of relevance with respect to comply-ing with the emissions limits.

Technical specifications of the ACU

•MPC5565 microcontroller (Freescale), 32-bit floating point µC, 80 MHz• 2 x 2 MB flash (internal + external), 192 KB RAM!!, 150 KB NVRAM• Model-based SW development and calibration (MATLAB/Simulink/Stateflow)• Operating voltage: 6 V – 32 V• Safety Integrity Level (SIL) 2• 3 CAN buses per ISO 11898-2, SAE J1939-11 (HS)• CAN Calibration Protocol (CCP)• On-board lambda sensor interface• Internal data logger (30 days)• 9 analogue inputs (PT200, NTC, 0 – 5 V)• 8 analogue inputs for active sensors with voltage output (0 – 5 / 10 V / Ub)• 4 PWM-enabled digital inputs (square wave, sinusoidal) and 2 inputs for inductivetransmitters

• 4 independent, short-circuit-proof sensor power supplies (3 x 5 V, 250 mA, 1 x 12 V, 450 mA)

• 1 switchable peripheral power supply for actuators (80 A)• 4 high-side outputs (7 – 15 A)

• 9 low-side outputs with current measurement (3 – 7 A), of which 1 for injector activation • 6 low-side outputs (0.5 – 1 A)• OBD and diagnostics protocols and front flashing:• OBD per SAE J1939-73 or ISO 15031-5 (SAE J1979) or ISO/PAS 27145 (WWH-OBD)• UDS diagnostics per ISO 14229 or KWP2000 per ISO 14230• Application tools: Vector CANoe, CANape, CANdela (via CCP)• Die-cast aluminium housing with following mechanical strengths:• Vibration: 9 g• Shock: 50 g• Ingress protection: IP67/69K• Operating temperature range: -40°C – +125°C• Various chemical resistance properties• ELV- (End of Life Vehicles) and RoHS-compliant• Service life• > 15 years• > 20,000 operating hours

The control unit sports the following interfaces:

• CAN interface for transmitting the necessary engine data (exhaustmass flow, exhaust-gas temperature, load, engine speed, enginetemperature, ambient temperature and, if available, nitrogen-oxideand residual-oxygen content)

• Inputs for transmitting the measured values of the individual sensors

The software encompasses functions for the:

• Strategy for diesel particulate filter regeneration and monitoring (including control of the exhaust flap, the heating element and the HCI)

• SCR dosing strategy• Diagnosis of the operating principle of components connected

ACU – Aftertreatment Control Unit, fuel-cooledACU – Aftertreatment Control Unit, air-cooled

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Innovative diesel emissions aftertreatment technology based on sintered metal offers key benefits to users

In cooperation with Volkswagen Powersystems, HJS Emission Technology has for the first time validated a coated, sintered metalparticulate filter for series installation that is designed to be mounted immediately downstream of the engine and to ensure compliance with the emissions levels of Stage IIIB (EU Non-road Directive 97/68/EG) and TRGS 554 (applicable in Germany).

The main challenges during development of this exhaust systemarose due to the limited amount of installation space available in themachines for which the system is intended and the high demandsarising from the additional loads a system installed in such close proximity to the engine will be subjected to. In addition to reliableand stable regeneration of the filters, the critical design criteria include a high ash holding capacity to minimise the number of servicing intervals and good cleanability of the filter. These were alsothe chief reasons why Volkswagen Powersystems has collaboratedclosely with HJS and has validated and is employing the latter's sintered metal filter technology for specific applications. This jointproject was kicked off back in the spring of 2010 with the aim of developing a highly durable solution for compliance with the emissions regulations laid down in Stage IIIB.

The unique construction of the SMF® (sintered metal filter) used givesit an extremely high ash holding capacity, enabling servicing intervals in excess of 7,000 operating hours (depending on engine

utilisation) to reduce operating costs significantly. Downtimes arealso cut thanks to the degree of simplicity and efficiency with whichthe filters can be cleaned, and the reusability of the filter modulesmeans they are highly cost-effective. The system has a useful servicelife of at least 20,000 operating hours as long as it is used as intended. At the same time, continuous regeneration (CRT = Continuously Regenerating Trap) optimises fuel consumption, whilethe engine's electronic control unit (ECU) monitors and manages thefield-proven operational concept.

With regard to emissions Stage IIIB compliance, Volkswagen Power-systems this year began supplying industrial-truck clients with its TDI2.0 – 455 MD industrial engine, coupled with one of the most innovative exhaust-gas aftertreatment systems currently on the market – giving them a genuinely clean solution. As a result, non-road machinery manufacturers who source VW industrial engines are already in a position to install engines in their machinerythat fulfil the even more stringent PM limits agreed for future emissions legislation.

The SMF®-based diesel emissions aftertreatment system from HJS, developed and homologated for this 2.0-l common rail engine willin future be a standard component of Volkswagen's modular partskit for its industrial engines and from 2013 will be installed as original equipment in all applications configured to meet Stage IIIB.

DPF® system for VW Powersystems Filter module of DPF® system for VW Powersystems

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Development expertise: Tools and methods

HJS uses the same CAD systems as its clients, plus a selection of simulation and calculation programs. The flow mechanics (backpressureand distribution), strength and acoustic properties are optimised veryearly on in the project. Proven methods and tools (computational fluiddynamics (CFD) and the finite element method (FEM)) are used to obtain a high level of product maturity at a very early stage and toavoid extra and excessive development work.

Development toolsDevelopment tools such as FMEA (Failure Modes and Effects Analysis)and the Design Verification Plan and Report (DVP&R, for short) are constituent parts of all development phases.

Verification of the development results is conducted on a wide range ofdifferent test benches. The main verification tests are as follows:

• Flow mechanics test on the flow bench

• Fatigue strength test on the hot-shake test bench

• Function tests on the entire system, conducted on the engine testbench

• Final vehicle testing to verify the overall system installed in the vehicle, conducted in cooperation with the client. This course of actionenables us to produce the development results within the time scheduled and at the cost agreed.

This enables us to speed up development and cut costs, particularlywhen it comes to highly complex tasks such as optimising 2-phaseflows using vaporised media like AdBlue® (see page 8) or diesel. If, forexample, the exhaust temperature is to be raised to 650°C by injectingdiesel fuel downstream of the engine and using a diesel oxidation catalyst, high levels of uniformity in the distribution both of the exhaust gases and the hydrocarbons must be ensured, because theDOC could otherwise potentially suffer undesirably high thermal loading in the event of unfavourable local combinations of exhaustmass flow and fuel mass flow. The illustration shows a snapshot fromthe transient modelling of interaction between a fuel spray with theflow guidance zones.

Simulation of fuel-PM deposits and vaporisation of the injected fuel

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Development expertise: Control and software

As a recognised standard that is widely used by vehicle and enginemanufacturers (OEs) alike, the V process is employed by HJS in thedevelopment of its ECU platform. We have systematically built up andexpanded our expertise in this field over the past years, to such anextent that the first model-based software versions are already testedand optimised very early on in the project in field trials, with the aidof rapid control prototyping. The result is a new generation of controlunits that sets the benchmark for platform control units in the dieselexhaust-gas aftertreatment segment.

Development in accordance with V process

Thanks to the distinct modularity of the software modules, it is possibleto assemble a perfectly scaled system to satisfy any customer demands.The high-level software consists of a large number of modules, each

Modular SW conceptmodule having been developed specific to the respective requirements.These are implemented in the overall architecture/API by means of sub-APIs (Signal Conditioning, SCR, DPF®, etc.).

Simulink

V modell

Example of the modular SW concept

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Owing to the huge number of different vehicle, machine and enginevariants in the on-road and non-road sectors and the resultingnumber of system variants, a way must be found to minimise theamount of time, resources and costs spent on each individual application. This is why the development path known as "StandaloneDiesel Emissions Aftertreatment" is being followed, which, throughthe use of functionally combinable modules, provides the necessarydegree of freedom to arrive at the best application.

Step 1: Formulation of the requirement profile based on the rawemissions and of the emissions target. Based in turn on this requirement profile, the right system configuration is determined bycarrying out simulations.

Step 2: The system configuration defined is assigned further detailand parameters in the simulation environment. The exhaust-gasaftertreatment system mapped as a model in this way is then linkedwith the models of the control unit modules and an emissions

simulation. A computer-aided precalibration of the control units isthen conducted on this basis.

Step 3: In this step, the system is actually integrated and put intooperation.

Step 4: Based on selected operating points, initial validation of thesystem developed and of the precalibration is carried out and theapproach defined ensured in the process.

Step 5: In the fine calibration step, the focus is put not only on theemissions characteristics but also on optimising variables such asefficiency, cost effectiveness and monitoring strategies (OBD).

Step 6: The final step consists of checking that all aspects have beensatisfied. In addition to the points already mentioned, this includesfor example the longevity of the system and the environmental requirements.

Development expertise: Applications

Example of an application:

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Development expertise: Acoustics

Limits governing pollutant emissions such as particulates and nitro-gen oxides are not the only regulations applicable to commercial ve-hicles and mobile machinery. These applications are also subject toregulations stipulating noise emissions. One example in the case ofmobile machinery is the EU Directive 2005/88/EC „Noise Emission inthe Environment by Equipment for Use Outdoors”. This directive re-quires that, in particular cases, a machine equipped with an exhaust-gas treatment system be fitted with anadditional silencer if necessary.

HJS has more than 10 years of extensive know-how in the field ofacoustic components and silencers for industrial applications – inparticular, in relation to the six crucial demands made on acousticcomponents: exhaust backpressure, surface-borne noise, orifice noise,service life, weight and cost.

An acoustic component is manufactured specifically for a respectiveapplication in line with the requirements. There is a choice of threeoptions: a reflection (or baffle) silencer, an absorption silencer, or acombination of these two. HJS has developed a modular range ofcomponents that gives the flexibility to construct a solution custo-mised specifically to each customer's needs. The range of folded, stan-dard silencers is available in diameters of up to 300 mm and lengthsof 600 mm. Silencers with an oval shape of 300 x 290 mm and alength of up to 600 mm can also be supplied. There are also weldedversions for engine power outputs up to 400 kW.

Another speciality of HJS is the design, production and homologa-tion of silencers with integrated spark arresters and aspirators, thatis, dust extraction devices for air filters. What's more, the companyuses calculation tools for simple linear and non-linear methods. Spect-ral examinations using low-reflection engine test benches and rollerdynamometers are just as feasible as mobile measurement for in-si-tuation evaluation of customers' requirements.

All in all, HJS offers the entire range of acoustic components requi-red for mobile non-road and construction machinery:

1. Standard exhaust systems (front pipes, vibration isolating ele-ments, silencers and tailpipes) for machines for which future le-gislation does not require exhaust treatment systems

2. Add-on components for HJS exhaust treatment systems, with op-timised acoustic components for compliance with the limits

3. Integration of particulate filters and catalytic converters, which infuture will be certified and supplied together with engines andmay possibly require additional acoustic components

Industrial silencer variety

• Technical support and concepts • Design and calculations with 3D CAD-systems• Highly qualified prototyping• Flexible production of varying lot sizes • Broad application spectrum – Types varying from 0,7 ltr. - 50 ltr. Volume

© HJS 2013 Last update 13.05.2013 Subject to change without notice.

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