Browse Topic: Engine mounts
Due to stringent emission norms, all OEMs are shifting focus from Internal combustion engine (ICE) to Electric vehicle (EV). NVH refinement of EVs is challenging due to less background noise in EVs in comparison with ICE vehicles. Motor whine noise is perceived inside cabin till the speed of 20 kmph. Vehicle is powered by electric powertrain (EPT). Electric powertrain is connected to the subframe with the help of three powertrain mounts. Subframe is connected to the body with the help of four mounts. With the help of Transfer Path Analysis (TPA), it is identified that the noise is structure borne and the dominant path is identified. By optimizing the stiffness of the EPT mounts, the structure borne noise levels are reduced. But reducing the stiffness of EPT mount deteriorated the road noise levels. The reason behind deterioration of road noise is investigated. The performance of double isolation of EPT is compared with single isolation of EPT with respect to both road and motor noise
The stiffness and positioning of engine mounts are crucial in determining the powertrain rigid body modes and kinetic energy distribution. Therefore, optimizing these mounts is essential in the automotive industry to separate the torque roll axis (TRA) and minimize vibration. This study aims to enhance mount locations by isolating the engine rigid body modes and predicting the inter-component force (ICF) and transfer function of the vehicle. The individual ICFs for engine mountings are calculated by applying a unit force at the bearing location. Critical frequencies are identified where the amplification exceeds the unit force at the mounting interface between the engine and the frame. The transfer function approach is utilized to assess the vibration at the handlebar. Both ICF and transfer functions analyze the source and path characteristics linked to critical response frequencies. This understanding aids in enhancing mounting positions to minimize vibration levels, thereby enhancing
This SAE Aerospace Recommended Practice (ARP) describes a method of conducting an endurance test using contaminated air when the applicable specification requires non-recirculation of the contaminants. The objective of the test is to determine the resistance of the engine mounted components to wear or damage caused by the contaminated air. The method described herein calls for non-recirculation of the contaminants and is intended to provide a uniform distribution of the contaminant at the inlet to the Unit Under Test (UUT). The UUT may require the use of a hydraulic fluid for actuation of components within the test unit. Contamination of the test hydraulic fluid is not part of this recommended practice. If contaminated hydraulic fluid is required by the applicable test specification, refer to MAP749.
NVH is of prime importance in buses as passengers prefer comfort. Traditionally vehicle NVH is analysed post completion of proto built however this leads to modifications, increases cost & development time. In modern approach physical validation is replaced by CAE. There are many sources of NVH in vehicle however this article is focused about the methodology to improve NVH performance of bus by analysing and improving the stiffness and mobility of various chassis frame attachment points on which source of vibrations are mounted or attached. In this study chassis frame attachment stiffness of Engine mounts and propeller shafts is focused.
With the advancement of regulatory norms in automobile industry, there is a challenge to meet performance efficiency targets, especially with a lightweight platform, while providing superior driving experience to customers. The shift towards weight optimization, makes the vehicle structure more susceptible to transfer a diverse range of noise and vibrations through body. Although most undesirable noises perceived inside the cabin can be reduced by superior technology engine mounts and NVH packaging, all such solutions lead to cost addition. Intelligent considerations in part design can be used to supplement predictable transfer paths to quell the unwanted vibrations. One such case is of the gear whine noise in certain rpm bands caused by inherent gear meshing frequency coinciding with natural frequency of an engine mounting bracket. This paper demonstrates two methodologies to counter such a phenomenon, either through engine mount bracket natural frequency optimization or addition of a
This Paper has as objective to describe the powertrain mount system and its relation with the Power Hop phenomenon. It will be present the Powertrain mounts stiffness characteristics and how the mounts manage the loads inputs. In this study, we will review a summary about powertrain mounts main characteristics to help the understanding how to establish the static and dynamic characteristics, with the engine torque applied over the system. It will be present how the Powertrain mounts shall manage the loads inputs. As a Case Study, it was applied one small passenger vehicle as hardware. This vehicle presents the powertrain mounts system as pendulum three points configuration. In addition, this vehicle presents the Power Hop phenomenon mainly in Reverse take off flat road. The required load data was collected through load cells installed on the powertrain mount system. The Power Hop phenomenon is mainly impacted by the rear mount, so the load data is related to rear mount direction X. The
Many chassis and powertrain components in the transportation and automotive industry experience multi-axial cyclic service loading. A thorough load-history leading to durability damage should be considered in the early vehicle production steps. The key feature of rubber fatigue analysis discussed in this study is how to define local critical location strain time history based on nominal and complex load time histories. Material coupon characterization used here is the crack growth approach, based on fracture mechanics parameters. This methodology was utilized and presented for a truck engine mount. Temperature effects are not considered since proving ground (PG) loads are generated under isothermal high temperature and low frequency conditions without high amounts of self-heating. This novel methodology for fatigue life calculation involves finding independent load channels and mapping all load history through converting single or multichannel load-displacement history into stress
The powertrain mount is an important component, which reduces the vibrations generated from the powertrain. Vibration isolation is achieved with help of modal separation by predicting the kinetic energy fraction (KEF) and natural frequency (NF) at each mode. The soft mounts reduce vibrations transferred from the engine to the chassis, but if stiffness is very low, the displacement of the mount will be high, and hence, the lifetime of the mount will be less. Vibration isolation using a powertrain mount is a compromise between the displacement of the mount, displacement of the center of gravity of the powertrain, KEF, and NF. In this paper knowledge-based engineering (KBE) application methodology is explained to initially find out the optimum values of mount parameters using permutation and the combination of mount stiffness, mount angle, and mount locations. Using these permutations and combinations, KEFs, NF, and the displacement of the center of gravity of the powertrain are found. At
This document provides an overview on how and why EGR coolers are utilized, defines commonly used nomenclature, discusses design issues and trade-offs, and identifies common failure modes. The reintroduction of selectively cooled exhaust gas into the combustion chamber is just one component of the emission control strategy for internal combustion (IC) engines, both diesel and gasoline, and is useful in reducing exhaust port emission of nitrogen oxides (NOx). Other means of reducing NOx exhaust port emissions are briefly mentioned, but beyond the scope of this document.
The hybrid structure of Engine Mounts made of rubber casing with cast iron reinforcing. Use of two materials made it unique both in application and testing. The rubber provides damping for engine vibrations and the cast iron provides necessary strengthening to hold the heavy engine in place. In this research paper the FEA (Finite Element Method) methodology is being discussed to evaluate and optimize the design analysis to enhance overall engine mount capacity. The existing and modified designs are validated and considerable improvement is being observed in modified design in physical testing. Accurate modeling of engine mounts assembly is presented in this paper. FEA analysis results have good correlation with physical validation for both designs. Impact of design parameters of rubber mounts has been presented.
This SAE Aerospace Recommended Practice (ARP) provides a guide for the preparation of a helicopter engine/airframe interface document and checklist. This document and checklist should identify the information needed by the engine manufacturer and the aircraft manufacturer to integrate the engine design with the aircraft design and either provide this information or give reference to where this information is located. The intent is to assure that the engine manufacturer and the airframe manufacturer identify and make provision for this information so it can be easily accessible to either manufacturer as needed in the development stages of an engine-airframe integration project. A related document, SAE Aerospace Information Report AIR6181, provides guidance on creating an interface control document (ICD) which addresses a subset of the aircraft-engine interface information concerning the physical and functional interfaces of the electronic engine control system (EECS) with the aircraft
The torque required to tighten any threaded joint is different from the necessary torque to untighten threaded bolt or nut, and it is not observed or widely known since this is a regular and straightforward operation. Typically the torque needed to untighten a newly tightened clamp is around 10% to 30% less than the torque to stretch it further. During tightening a threaded bolt, a significant amount of torque required to overcome friction in the threads and under the nut face. The proportion of the torque used to overcome frictional resistance depends upon the friction value. When we tighten a joint with a coefficient of friction of 0.12, only about approximately 14% of the torque required to stretch the fastener producing the clamp load with 86% of the torque is lost overcoming friction. The torque needed to pull the bolt always acts in the untightening direction, resulted in untightening torque lags behind the tightening torque. Sufficient preload has to be there in the bolted joint
Electromagnetic semi-active hydraulic engine mount (HEM) with double inertia tracks can realize the opening and closing of the inertia tracks through the control of electromagnetic actuator, so as to meet the needs of vibration isolation in different working conditions, but the cost is high. In this paper, without using electromagnetic actuator, a mechanical semi-active HEM with double inertia tracks is designed and manufactured with simple structure and low cost. In this study, the feature of mechanical semi-active HEM with double inertia tracks is that a baffle-current limiting column structure is added in the inertia track. Under different excitation amplitudes, the baffle-current limiting column structure can open and close the inertia track passively. Several mechanical semi-active HEM with double-inertia tracks samples and conventional inertia tracks HEM samples are manufactured and the dynamic characteristics of these samples under low frequency excitation are tested. By
This document summarizes types of heat sinks and considerations in relation to the general requirements of aircraft heat sources, and it provides information to achieve efficient utilization and management of these heat sinks. In this document, a heat sink is defined as a body or substance used for removal of the heat generated by thermodynamic processes. This document provides general data about airborne heat sources, heat sinks, and modes of heat transfer. The document also discusses approaches to control the use of heat sinks and techniques for analysis and verification of heat sink management. The heat sinks are for aircraft operating at subsonic and supersonic speeds.
The purpose of this SAE Aerospace Recommended Practice (ARP) is to standardize locations of aircraft ground service connections to accommodate the trend toward fixed systems, which use the passenger boarding bridge and/or underground “pop-up” or pit systems as a source of utilities. It must be recognized that, in standardizing the locations of the aircraft service connections, they must continue to be served efficiently in those instances where mobile ground support equipment is used. There is an ever increasing number of fixed installations for aircraft servicing. The objectives to be met by standardizing the locations of the aircraft service connections are the following:
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