Browse Topic: Transmissions
A good Noise, Vibration, and Harshness (NVH) environment in a vehicle plays an important role in attracting a large customer base in the automotive market. Hence, NVH has been given significant priority while considering automotive design. NVH performance is monitored using simulations early during the design phase and testing in later prototype stages in the automotive industry. Meeting NVH performance targets possesses a greater risk related to design modifications in addition to the cost and time associated with the development process. Hence, a more enhanced and matured design process involves Design Point Analysis (DPA), which is essentially a decision-making process in which analytical tools derived from basic sciences, mathematics, statistics, and engineering fundamentals are used to develop a product model that better fulfills the predefined requirement. This paper shows the systematic approach of conducting a Design Point Analysis-level NVH study to evaluate the acoustic
Wind noise is one of the largest sources to interior noise of modern vehicles. This noise is encountered when driving on roads and freeways from medium speed and generates considerable fatigue for passengers on long journeys. Aero-acoustic noise is the result of turbulent and acoustic pressure fluctuations created within the flow. They are transmitted to the passenger compartment via the vibro-acoustic excitation of vehicle surfaces and underbody cavities. Generally, this is the dominant flow-induced source at low frequencies. The transmission mechanism through the vehicle floor and underbody is a complex phenomenon as the paths to the cavity can be both airborne and structure-borne. This study is focused on the simulation of the floor contribution to wind noise of two types of vehicles (SUV and Sports car), whose underbody structure are largely different. Aero-Vibro-acoustic simulations are performed to identify the transmission mechanism of the underbody wind noise and contribution
Centralization of electrically driven hydraulic power packs into the body of aircraft has increased attention on the noise and vibration characteristics of the system. A hydraulic power pack consists of a pump coupled to an electrical motor, accumulator, reservoir, and associated filter manifolds. In previous studies, the characteristics of radiated acoustic noise and fluid borne noise were studied. In this paper, we focus on the structure-borne forces generated by the hydraulic pump characterized through blocked force measurements. The blocked force of the pump was determined experimentally using an indirect measurement method. The indirect method required operation with part under test fixed to an instrumented receiver structure. Measured operational accelerations on the receiver plate were used in conjunction with transfer function measurements to predict the blocked forces. Blocked forces were validated by comparing directly measured accelerations to predicted accelerations at
In addition to providing safety advantages, sound and vibration are being utilized to enhance the driver experience in Battery Electric Vehicles (BEVs). There's growing interest and investment in using both interior and exterior sounds for pedestrian safety, driver awareness, and unique brand recognition. Several automakers are also using audio to simulate virtual gear shifting of automatic and manual transmissions in BEVs. According to several automotive industry articles and market research, the audio enhancements alone, without the vibration that drivers are accustomed to when operating combustion engine vehicles, are not sufficient to meet the engagement, excitement, and emotion that driving enthusiasts expect. In this paper, we introduce the use of new automotive, high-force, compact, light-weight circular force generators for providing the vibration element that is lacking in BEVs. The technology was developed originally for vibration reduction/control in aerospace applications
Gear whine has emerged as a significant challenge for electric vehicles (EVs) in the absence of engine masking noise. The demand from customers for premium EVs with high speed and high torque density introduces additional NVH risks. Conventional gear design strategies to reduce the pitch-line velocity and increase contact ratio may impact EV torque capacitor or its efficiency. Furthermore, microgeometry optimization has limited design space to reduce gear noise over a wide range of torque loads. This paper presents a comprehensive investigation into the optimization of transfer gear blanks in a single-speed two-stage FDW electric drive unit (EDU) with the objective of reducing both mass and noise. A detailed multi-body dynamics (MBD) model is constructed for the entire EDU system using a finite-element-based time-domain solver. This investigation focuses on the analysis and optimization of asymmetric gear blank design features with three-slot patterns. A design-of-experiment (DOE
Noise transmission through the vehicle dash panel plays a critical role in isolating passengers from noise sources within the motor bay of the vehicle. Grommets that contain electrical harness routing as well as HVAC lines are examples of dash panel pass-throughs that should be selected with care. Acoustic performance of these components is generally characterized in terms of measured quantities such as noise reduction (NR), sound transmission loss (STL), and insertion loss (IL). These measurements need to be carried out per SAE or ASTM standards in appropriate anechoic or reverberant chambers as this is important for consistency. This work explores an in-situ measurement of the grommet STL performance in the vehicle environment. It utilizes a repurposed vehicle with its cabin retrofitted to serve as an anechoic chamber and its frunk acting as a reverberant chamber. Results of this in-situ measurement are then compared to measurements following industry standards to discuss the
A proprietary metamaterial has been shown to reduce panel vibration. In this particular case, the metamaterial is designed to be attached to the edge of a glass panel and can reduce panel vibration and noise transmission due to wind or other sources into the vehicle interior. Acoustic transmission loss and panel vibration assessments show the benefit of this approach.
Modern communication networks rely on optical signals to transfer vast amounts of data. But just like a weak radio signal, these optical signals need to be amplified to travel long distances without losing information. The most common amplifiers, erbium-doped fiber amplifiers (EDFAs), have served this purpose for decades, enabling longer transmission distances without the need for frequent signal regeneration. However, they operate within a limited spectral bandwidth, restricting the expansion of optical networks.
The automotive subframe, also referred to as a cradle, is a critical chassis structure that supports the engine/electric motor, transmission system, and suspension components. The design of a subframe requires specialized expertise and a thorough evaluation of performance, vehicle integration, mass, and manufacturability. Suspension attachments on the subframe are integral, linking the subframe to the wheels via suspension links, thus demanding high performance standards. The complexity of subframe design constraints presents considerable challenges in developing optimal concepts within compressed timelines. With the automotive industry shifting towards electric vehicles, development cycles have shortened significantly, necessitating the exploration of innovative methods to accelerate the design process. Consequently, AI-driven design tools have gained traction. This study introduces a novel AI model capable of swiftly redesigning subframe concepts based on user-defined raw concepts
Electrified powertrains, including Power Splits (Electrically Variable Transmissions), Range Extenders (Series Hybrids), and Electric Vehicles with Disconnect Actuators, offer significant flexibility in managing input actuator acceleration and output torque, drawing power from shared sources. The Hybrid Supervisory Controller (HSC) plays a crucial role in balancing these parameters to meet performance and drivability metrics, yet it often faces challenges under power constraints or sudden high output demands, which can lead to imbalanced control, reduced actuator performance, and unintended vehicle motion. Traditional solutions have typically prioritized one control objective over others, compromising overall system performance. This paper introduces an advanced control strategy that optimally distributes control efforts across multiple actuators with overlapping and conflicting objectives. By resolving these conflicts, the proposed approach ensures system stability and enhances
This paper explores the application of a modeled torque converter in the real-time control of a hybrid electric powertrain. The study aims to determine the optimal gear selection and engine speed target required to meet driver demands. It also delves into the concept of torque converter input inertia compensation, particularly during open, open-to-close, and close-to-open states. The primary objective is to achieve the intended driver torque while minimizing torque sag and bumps during these transitions. This approach ensures improved powertrain response and maintains system integrity within the operational limits of the battery, motors, and engine.
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