<p>This thesis has the overall objective to develop the optimum sealing system between the retarder and transmission. Today, there is a pressure-relief and two radial seals separation between the retarder and transmission. It has been found that carbon residue formation may occur between retarder axle and seal lips with, in some cases, leakage as a result.</p><p>We have in this thesis tried to explain the phenomenon of carbon residue, how it is formed and why it can be seen just on the seals? A rig test was conducted where we show how friction, speed, transmission temperature and mitigation phases of the retarder affects temperatures in the sealing environment. Factors affecting the coke structure are reported, together with proposals for measures that provide a mitigating seal environment. The material is PTFE, which is standard in the seals today; we believe meets all requirements for the sealing material.</p><p>The final recommendation is a tripartite cooperation between Scania, a petroleum company and an additive manufacturer where the different base oils and additive tested as multi-factorial experiments to identify what gives the best results. On transmission side we recommend to ensure a constant oil flow to the seal.</p>

För att öka köreffektivitet och säkerhet samt minska bromsarnas slitage är de flesta av Scanias lastbilar och bussar utrustade med en hjälpbroms, så kallad retarder. En retarder arbetar generellt sett enligt någon av följande två principer. Dels en elektromagnetisk variant av retarder som bromsar bilens kardanaxel, drivaxlar eller växellåda genom att utnyttja elektromagnetisk induktion, eller som i Scanias fall där man använder sig av en hydrodynamisk tillsatsbroms som bromsar bilens kardanaxel genom att slunga vätska inom ett skovelsystem. Bromsenergin övergår då till värmeenergi som i sin tur kyls bort av bilens ordinarie vattenkylsystem. Bromsmomentet styrs via trycket som råder mellan skovelbladen. Som mest överträffar retardern den effekt som bilens motor kan leverera. Då retardern inte används är skovelsystemet trycklöst. Men även då skapas det dock ett litet släpmoment i retardern eftersom den fortfarande roterar med växellådan. Detta släpförlustmoment är en bråkdel jämfört med det moment som skapas vid bromsning men ur bränslebesparingssynpunkt är det ändå viktigt att det hålls på minimal nivå. Detta examensarbete syftar till att utreda hur dessa släpförluster kan minimeras genom att via konceptstudier ta fram den bäst lämpade släpförlustreduceringsmetoden för Scanias retarder. En studie på konkurrenter och andra applikationer där inspiration skulle kunna inhämtas genomfördes och ett antal koncept togs fram. Därefter genomfördes en provkörning av en konkurrentretarder för ytterligare fördjupade kunskaper om problemet. Där samtidigt ett av koncepten med en bländarskiva mellan rotor och stator provades, dock med ett resultat som inte kunde anses tillräckligt. Efter detta kunde det konstateras att den bäst lämpade släpförlustreduceringsmetoden för Scania bör vara att helt frikoppla retardern från växellådan vid avaktivering då ett flertal av de största förlusterna som mättes upp kunde härledas in diverse tätningar och lager och inte till själva retardern. Denna frikoppling bör förslagsvis ske genom någon form av synkroniseringsinkoppling för att minimera vikt, storlek och kostnad. Slutligen kan det konstateras att kunskapen om vad som exakt sker i en retarder är begränsad och att det är ett komplext område. Vidare bör simuleringsmodeller användas för att minimera utvecklingsarbetet och ytterligare studier på hur en effektiv frikoppling kan användas bör genomföras. Nyckelord: retarder, släpförluster, växellåda / In order to increase the drive efficiency and safety as well as to minimize the brake wear, most Scania trucks and busses are equipped with a complementary brake system, also known as a retarder. A retarder generally works under one of the following two principles. An electromagnetic retarder that brakes the propeller shaft, drive axles or the gearbox using electromagnetic induction or as in Scania's case using a hydrodynamic brake that brakes the propeller shaft by pumping a fluid thru a rotating turbine shaped system. The braking energy then turns to heat which then cools off by the engine’s cooling system. The brake power is controlled by the fluid pressure in the retarder. At its maximum, the brake power exceeds the power of the engine. When the retarder is deactivated, the system is not pressurized. But even then, it creates a small slip loss, because the retarder is still rotating with the gearbox. This slip loss is a fraction compared to the braking torque than can be used, but from a fuel efficiency standpoint it is still important that it is kept at a minimum. The goal of this master thesis is to investigate how to minimize these losses. To find out which the best suited solution for Scania would be, different concept studies has been carried out. A study of competitors and other applications where further inspiration could be obtained was conducted and a number of concepts were developed. Thereafter a test run of a retarder from a competitor for further in-depth knowledge was conducted. At the same time one of the concepts with an aperture plate between the rotor and stator was tested on the competitor retarder. With a result that could not be considered sufficient. After this it was found that the most appropriate slip reduction method should be to completely disengage the retarder from the gearbox at deactivation since most of the losses that was measured could be traced to various seals and bearings and not to the retarder itself. The decoupling should be done through some kind of synchronization unit to minimize weight, size and cost. Finally it was observed that the knowledge about what’s exactly happening in the retarder is limited and that it is a complex area. Furthermore should the use of simulation models enhance to minimize the development work and further studies about how to disengage the retarder in the most effective way should be worked out Keywords: losses, retarder, slip

This thesis has the overall objective to develop the optimum sealing system between the retarder and transmission. Today, there is a pressure-relief and two radial seals separation between the retarder and transmission. It has been found that carbon residue formation may occur between retarder axle and seal lips with, in some cases, leakage as a result. We have in this thesis tried to explain the phenomenon of carbon residue, how it is formed and why it can be seen just on the seals? A rig test was conducted where we show how friction, speed, transmission temperature and mitigation phases of the retarder affects temperatures in the sealing environment. Factors affecting the coke structure are reported, together with proposals for measures that provide a mitigating seal environment. The material is PTFE, which is standard in the seals today; we believe meets all requirements for the sealing material. The final recommendation is a tripartite cooperation between Scania, a petroleum company and an additive manufacturer where the different base oils and additive tested as multi-factorial experiments to identify what gives the best results. On transmission side we recommend to ensure a constant oil flow to the seal.

Substantial impacts of aerosols on climate and public health underscore the need for accurate characterization of atmospheric aerosol distributions and microphysical properties. The Multiangle SpectroPolarimetric Imager (MSPI) combines accurate multispectral, multiangle, and polarimetric technologies in a single instrument that images a wide swath on the Earth's surface to advance aerosol remote sensing capabilities. MSPI is required to have 3% radiometric uncertainty and 0.005 degree of linear polarization (DoLP) uncertainty. These are difficult requirements that push the limits of available technologies needed to perform space-based polarimetric imaging. This work examines three topics related to MSPI fabrication and calibration: polarization errors and their correction, achromatic, athermal, quarter wave retarder fabrication, and analysis of a polarization state generator (PSG) for MSPI polarization calibration confirmation.MSPI polarization errors may arise from surface geometry of the optical components, coatings, and quarter wave plates (QWPs). Static polarization errors can be calibrated out, but result in decreased SNR. Polarization errors that drift following calibration cannot be corrected, so a sensitivity analysis is used to set time-varying diattenuation and retardance magnitude tolerances. QWPs are required to work in concert with the PEMs to modulate the linear component of the Stokes vector. A three-material achromatic, athermalized QWP was designed, fabricated and its performance validated. Analysis indicated that the compound QWP was unlikely to meet the requirements if plates were specified by thickness. To address this, a method for QWP fabrication was developed that involves monitoring retardance during polishing. To verify MSPI performance, a PSG was built and calibrated which outputs weakly linearly polarized light with DoLPs varying from 0.0005 to 0.4 with 0.0005 uncertainty by passing nearly unpolarized light through a tilted plane parallel plate. The PSG was intended to act as a calibration standard based on calculated DoLP, but proved difficult to model. Therefore, the DoLP was instead measured to repeatability of 0.0005. Finally, example spectropolarimetric image data taken with MSPI was presented. Work on a follow-on prototype continues that will advance the technologies needed to realize the space-based, fully capable MSPI.

The Daniel K Inouye Solar Telescope (DKIST), when completed in 2019 will be the largest solar telescope built to date. DKIST will have a suite of first light polarimetric instrumentation requiring broadband polarization modulation and calibration optical elements. Compound crystalline retarders meet the design requirements for efficient modulators and achromatic calibration retarders. These retarders are the only possible large diameter optic that can survive the high flux, 5 arc minute field, and ultraviolet intense environment of a large aperture solar telescope at Gregorian focus. This dissertation presents work performed for the project. First, I measured birefringence of the candidate materials necessary to complete designs. Then, I modeled the polarization effects with three-dimensional ray-tracing codes as a function of angle of incidence and field of view. Through this analysis I learned that due to the incident converging F/13 beam on the calibration retarders, the previously assumed linear retarder model fails to account for effects above the project polarization specifications. I discuss modeling strategies such as Mueller matrix decompositions and simplifications of those strategies while still meeting fit error requirements. Finally, I present characterization techniques and how these were applied to prototype components.

This dissertation addresses the creation of polarization vortex beams. Vortex retarders are components with uniform retardance but a fast axis which rotates around its center with can create polarization vortices. The goal was to develop a simple method for producing vortex retarders for visible wavelengths, with a continuous fast axis, and for multiple vortex modes.The approach was to use photo-aligned liquid crystal polymers (LCP). The target was a halfwave retardance for wavelengths in the range of 540~550nm. A photo-alignment layer was spin-coated onto a substrate, baked, and alignment was set through exposure to linear polarized UV (LPUV) light. The alignment layer was exposed through a narrow wedge shaped aperture located between the substrate and polarizer. Both the polarizer and substrate were continuously rotated during exposure process in order to create a continuous variation in photo-alignment orientation with respect to azimuthal locations on the substrate. The mode of the vortex retarder was determined by the relative rotation speeds. The LCP precursor was spin-coated and subsequently polymerized using a UV curing processes. Elements produced were analyzed by measuring the space variant Mueller Matrix of each component. Our measurements demonstrated that the vortex retarders were half wave plates with a continuous fast axis orientation. Measurement of the center region of the vortex retarders identifies a 100-200um region of disorientation. At 0.5mm resolution, a high depolarization index in the center of the vortex retarders was observed. The DOP was low in the center for a horizontal linear polarized input field but remained high for circular polarized input.The viability of these components was assessed by determining the point spread matrix (PSM) and the optical transfer matrix (OTM) and comparing these to theoretical calculations. The agreement between the measured and predicted PSM was excellent. The major difference was the non-zero response in the m03 and m30 elements indicating circular diattenuation. The OTM comparison between measured and predicted demonstrated an excellent quantitative match at lower spatial frequencies and a good qualitative match at higher spatial frequencies. Measured results confirm that vortex retarders produced using photo-aligned LCP produce near theoretical performance in an optical system.

Meanderline structures are widely used as engineered birefringent materials for waveplates and retarders at radiofrequencies, and have been previously demonstrated at frequencies up to 90 GHz in the millimeter-wave band. In this dissertation, we present results related to the modeling, fabrication, and experimental characterization of meanderlines across the range from 30 to 100 THz, in the long-wave and mid-wave infrared bands. Specific issues addressed in these new designs include spectral dispersion and angular dependence of the retardance, as well as axial ratio and throughput. The impact resulting from the infrared properties of the metals and dielectrics is explicitly included throughout. Several novel applications are identified, including integrated circular polarizers, reflective waveplates, and large-area polarization tags.

A simulation model for an automatic gearbox with primary retarder has been constructedand implemented, in this thesis. Together with other modelled vehicle components, thismodel could for example be used for fuel consumption estimation or optimizing vehicleparameters.The mechanical components and the control system inside the automatic gearbox weremodelled separately and then assembled into the nal gearbox model, using the objectorientedprogramming language Modelica. Modelica ensures that each individual componentcan be reused in other models.The gearbox model was validated through a number of test cycles designed to capturedierent vehicle behaviours. The test cycles were recreated in the simulation environmentand the simulation results could be compared to a real vehicle performing the same tests.Validation showed that the model succeeded in its goal, that the implemented model isreproducing similar behaviour as the real gearbox. With gear shifts taking place in aboutthe same situations and converter locking/unlocking occurring the same time in the simulationsas in the real vehicle testing. / I det här examensarbetet har en simuleringsmodell för en automatisk växellåda med primär retarder utvecklats och implementerats. Tillsammans med andra modeller från fordonoch drivlina skulle denna simuleringsmodell kunna användas för att uppskatta ett fordonsbränsleförbrukning eller till att optimera olika fordonsparametrar.De olika mekaniska komponenterna samt kontrollsystemet i växellådan modellerades separat.Dessa modeller kunde sedan sammanfogas för att bygga den slutliga växellådsmodellen.Alla modeller implementerades i det objektorienterade programmeringsspråket Modelica,som tillåter en stor återanvändningsbarhet till vardera enskild komponent.Den implementerade modellen verierades genom ett antal provcykler, utformade för attfånga olika beteenden hos växellådan. Dessa cykler har återskapats i simuleringsmiljön ochmed det kunde resultat från simuleringar jämföras mot data från ett verkligt fordon somutförde samma prov.Från verieringen har slutsatsen dragits att modellen uppfyllde målen med projektet. Målen var, att den slutliga simuleringsmodellen visar ett liknande beteende som en växellåda i ett verkligen fordon. Växlingar och låsning/upplåsning hos momentomvandlareninträande vid ungefär samma situationer i simuleringarna som i provningen med det verkligafordonet.

Quarter-wave retarders (QWR) that employ total internal reflection (TIR) and interference of light in a transparent thin-film coating at the base of a prism are presented. Explicit equations that guide the optimal design are provided. The optimal refractive index and normalized thickness of QWR coatings on glass and ZnS prisms are determined as functions of the internal angle of incidence from 45o to 75o. An achromatic QWR that uses an Si3N4- coated N-BK10-Schott glass prism is also presented with retardance error of 3o over the 400-600 nm wavelength range. An iterative procedure for the design of a polarizing beam splitter (PBS) that uses a form-birefringent, subwavelength-structured, one-dimensional photonic-crystal layer (SWS 1-D PCL) embedded in a high-index cubical prism is presented. The PBS is based on index matching and total transmission for the p polarization and total internal reflection for the s polarization at the prism-PCL interface at a 45o angle of incidence. A high extinction ratio in reflection ( 50 dB) over the 4-12 μm IR spectral range is achieved using a SWS 1-D PCL of ZnTe embedded in a ZnS cube within an external field of view (FOV) of ±6.6o and in the presence of grating filling factor errors of up to ±10%. Comparable results, but with a wider field of view, are also obtained with a Ge PCL embedded in a Si prism. A design for visible spectrum (553–713 nm) PBS SWS 1-D PCL of ZnTe embedded in a ZnS cube is also presented. The PBS shows a FOV of ±7o. A circular polarizing beam splitter (CPBS) with equal throughput for p and s polarization using SWS 1-D PCL embedded in a high-index cubical prism is introduced. A dual QWR in transmission and reflection with 50–50% CPBS is designed using the PCL. Such a CPBS shows large deviation from the design point as a result of small changes in the design parameters; e.g. a change of 10% in the filling factor results in 12o shift from the 90o phase shift between p and s polarizations, which limits the practical utility of the device.

A reflection retarder is a device that induces a change in the phase between the parallel and perpendicular components, of the electric field, to the plane of incidence while maintaining the relative amplitudes. A film-substrate reflection retarder is a reflection retarder that only consists of a film-substrate system. Film-substrate reflection retarders have been previously studied in the negative, zero, and positive systems. The type of system is determined by the relationship between the refractive index of the ambient N0, film N1, and substrate N2: if N1<(N0*N2)^(1/2) , the system is negative; if N1=(N0*N2)^(1/2), the system is zero; if N1>(N0*N2)^(1/2), the system is positive. It has been determined that is the condition required to achieve reflection retarders, in general. Angle-of-incidence tunable (AIT) retarder designs have not been investigated for the zero system, but have been studied in the negative system. An exact retarder in the zero system only exists at a single angle of incidence and a corresponding single film thickness. By approximating the retarder condition to allow the relative amplitudes to be within 5% of the exact value of unity, it is possible to realize unique AIT retarders in the zero system: retarders that can be operated over a continuous range of angles of incidence resulting in a large range of phase shifts approaching 360°. It is possible to have multiple angles of incidence with a difference of between their respective phase shifts. By inducing a phase shift of, it is possible to modulate the polarization of light. By employing an approximation of the retarder condition, AIT retarder designs were developed. The design’s tolerance to changes in design parameters is analyzed and discussed.