The purpose of this report was to investigate how an intake for a battery-powered leaf blowershould be designed to reduce sound emissions. A reduced sound emission improves both theworking environment for the user but also reduces disturbances to the surroundings. The workbegan with a market analysis of different leaf blowers’ intakes. Other industries and differenttypes of noise reduction systems were also investigated. The market analysis stated that animplementation of Helmholtz resonators in an intake has great potential to reduce the tonalsound that a battery-powered leaf blower emits. As the sound image of a battery-powered leafblower is very tonal, the idea with resonators was to reduce the tonal spikes to achieve a lowersound level. If the work could prove that the resonators provide a high effect in the area aroundthe tonal sound spikes, then with some optimization, the resonators could be adapted and lowerthe sound equally at these frequencies. The work then progressed with testing whetherresonators work effectively. The result of the test showed that resonators can dampenfrequencies with high power, which led to the work continuing with a Concept Generation. The concept generation resulted in four different concepts that all had different placements andimplementations of resonators in the intake. These concepts were tested again and comparedto a reference that did not have any sound dampening features. From this test, two conceptsperformed at a high level, which were Back Cone and Big and Large, and these were furtherdeveloped. Further development produced four different variants of Big and Large. These werevariants with different numbers of resonators. Back Cone was produced in three differentvariants with different sizes of resonators. The purpose of these variants was to investigate howthe size and number of resonators affect the sound dampening ability. These variants weretested according to ISO-22868:2021. The final test revealed that four prototypes achieve therequired value for sound minimization. However, several external parameters emerged that affected the test results. One parameter was likely a floor reflex between the leaf blower and themicrophone directly behind the intake. The influence of the external parameters leads to thecredibility of the test results being unclear and thus these prototypes cannot be approved. During the same test, a speaker was used as the sound source instead of the fan. In this test, itappears the same four prototypes achieve a sound-minimizing effect that achieves the requiredeffect in the same range as in the tests with a fan as a sound source. Even in this test, there wereseveral external parameters that affected the result and therefore the prototypes could not beapproved with certainty according to the requirements specification. The project can be summed up by stating that resonators have great potential to reduce thetonal sound that a battery-powered leaf blower generates. The project has also shown howdifferent placements of resonators affect the sound dampening effect. During test two, a prototype emerged that can be approved according to the requirement specification as itperformed 17,5 dB maximum sound dampening effect right above the tonal frequency and sixdB at the right frequency. The project cannot determine with certainty if the variants of intakeused in the final tests meet the requirement specification due to the external parameters thataffected the results. However, the project can state that the resonators have achieved an effectin all tests. The maximum effect achieved was analysed in test one and was 27 dB soundminimization. The project ends by proposing further work such as investigating how an intakewith resonators should be designed to be manufactured in mass production. The influence ofthe thickness of the intakes surface boundary layer on the effect of the resonator should also beexamined, as well as the distance of the resonator to the fan and the outer edge of the intakeshould be examined together with the several other points presented in the chapter Discussions.

Rapporten behandlar ett examensarbete inom Produktutveckling och Design vid Tekniska Högskolan på Jönköpings University 2020. Examensarbetet utfördes på uppdrag av Globe Group som avslutande del av utbildningen Maskinteknik. Arbetet har utförts av Alexandra Bachtay och Linnea Hellström. Arbetet bestod av att ta fram ett koncept på ett optimerat batteribälte hos produktsortimentet för Cramer. Globe Group har tre olika märken, där Cramers produkter är anpassad till professionella användare inom trädgårdsverktyg. Företaget utvecklar batteridrivna trädgårdsredskap. Därmed använder de sig av batteribälte i deras produktserie. I denna ser dem en del problem och därför har Globe Group utformat ett examensarbete med fokus på produktutveckling och konstruktion. Till en början söktes det efter en tydligare bild av användaren och produkten, därmed utfördes förstudier. Med hjälp av de som framkom under förstudien skapades två kravspecifikationer och funktionsanalyser för att kunna få ett bättre perspektiv på alla de olika delarna i produkten. Under skapandet av olika koncept delades det upp i tre områden, midjebälte, batterihållare samt infästning. När endast varsitt koncept kvarstod sammanställdes resultaten. Arbetet inriktas mot att skapa ett stabilare batteribälte med användarvänligheten i fokus. Resultatet av arbetet var ett nytt koncept på hur Cramer kan utforma sitt batteribälte för att tillgodose kundens behov. / The report deals with a bachelor's degree project in Product Development and Design at Jönköping University 2020. The thesis was carried out on behalf of Globe Group as the concluding part of the Mechanical Engineering program. The work was executed by Alexandra Bachtay and Linnea Hellström. The work consisted of developing a concept on an optimized battery belt in the product assortment for Cramer. Globe Group has three different brands, where Cramer's products are adapted to the professional gardener. The company develops garden tools driven by battery. Therefore they are having a battery belt in their product series. In this product they are seeing some problems and therefore Globe Group has designed this project focusing on product development and construction. Initially, a clearer picture of the user and the product was sought, thus feasibility studies were performed. With the help of those that emerged during the preliminary study, two requirements specifications and functional analyses were created in order to get a better perspective on all the different parts of the product. During the creation of different concepts, it was divided into three areas, waist belt, battery holder and attachment between the holder and belt. When only each area had one remaining concept, the results were later compiled into one final product. The work was focused on creating a more stable battery belt with user-friendliness in focus. The result of the work was a new concept on how Cramer can design its battery belt to meet customer needs.