Browse Topic: Differential gears
Automotive driveline imbalance is a result of rotating components or assemblies being manufactured with their centers of mass not being coincident with their centers of rotation. For vehicle mass production, an end-of-line (EOL) driveline balancing process may be required, depending on vehicle sensitivity and component control costing. In this investigation, the process and facility design for an EOL automotive driveline balancing process is outlined, including important considerations in the measurement configuration of the balancing facility. Initial results from prototype vehicle testing with conventional influence balancing techniques, based on commercially available equipment, are given. The role of the influence coefficient in the balancing process and of car-to-car variability in the influence coefficient were investigated. An equation for the influence coefficient was derived, providing an improved understanding of the nature of the influence coefficient, along with sources of
A driveline differential gear housing or diff-case is the heaviest component of a driveline that rotates at high velocities. core shift during diff-case casting is a major source of imbalance as casting cores can never be placed at the exact intended location. Core shift in the present case is defined as combination of pure translation along the parting plane and tilting about two orthogonal axes. Given the ranges of variation of these shift parameters, large numbers of random sampling of these variations are generated through Monte Carlo method where normal distribution of each of the core shift parameters is assumed. Static unbalance values of the diff-case from each of the instances of core shift is calculated using Boolean operation in MSC Adams View and a nonlinear data set is created. Next, a statistical model is created based on a neutral network-based fitting method to appropriately represent the set. The validity of the model is checked based on specific core shift cases to
Suppose we have two identical variable-inertia flywheels and we connect them to the inputs of a differential. The output is connected to the driveline of a vehicle. There are several types of three-element mechanical differentials (e.g. ring-gear/carrier, epicyclic, etc.). The specific type of 3-element mechanical differential is inconsequential in the following analysis except to say there are two inputs (e.g. side gears) and one output (e.g. carrier/ring-gear). What’s important is simply the relationship - For example, using the notation ‘a’ for the first side gear and ‘b’ for the second side gear and ‘c’ for the carrier, then the relationship is: c=(a+b)/2. Understand that ‘a’, ‘b’, and ‘c’ can each be an input or an output. Using the designation ‘omega’ (ω) then the relationship looks like this: ωc=(ωa+ωb)/2. So, we have one variable inertia flywheel (VIFa) and a second variable inertia flywheel (VIFb) connected to two side gears, a and b, and a vehicle driveline connected to the
The successful deployment of automated vehicles (AVs) has recently coincided with the use of off-board sensors for assessments of operational safety. Many intersections and roadways have monocular cameras used primarily for traffic monitoring; however, monocular cameras may not be sufficient to allow for useful AV operational safety assessments to be made in all operational design domains (ODDs) such as low ambient light and inclement weather conditions. Additional sensor modalities such as Light Detecting and Ranging (LiDAR) sensors allow for a wider range of scenarios to be accommodated and may also provide improved measurements of the Operational Safety Assessment (OSA) metrics previously introduced by the Institute of Automated Mobility (IAM). Building on earlier work from the IAM in creating an infrastructure- based sensor system to evaluate OSA metrics in real- world scenarios, this paper presents an approach for real-time localization and velocity estimation for AVs using a
Adjuster rings are used in commercial vehicle axle assembly to preload differential bearings and provide support in the axial direction. Adjuster along with the carrier and bearing cap combined to form a threaded joint. Adjuster with external threads engages with internal threads formed in carrier and bearing cap. Preload in differential assembly maintains the system rigidity and helps to maintain an optimized hypoid gear engagement. An adequate preload is important to achieve a desirable bearing life. Reduction in thread engagement at adjuster joint fully or partially will cause a reduction in preload and can lead to gear misalignment. This can cause severe durability concerns. In some cases, it is observed that under vehicle operating loads adjuster ring is backed off from its assembled condition by bending the split pin (split pin is, positive lock, used to maintain adjuster position) and adjuster threads were stripped off. Adjuster ring threads are designed using standard
The given paper presents the main elements of frictional power loss distribution in an automotive axle for passenger car. For reference two different axles were compared of two different sizes to understand the impact of size and ratio of gear and bearings on power loss characteristics. It was observed that ~50% of total axle power loss is because of pinion head-tail bearing and its seals, which is very significant. Roughly 30% of total power loss is contributed by pinion-ring gear pair and differential bearings and remaining ~20% by wheel end bearing and seals. With this study the automotive companies can take note of the area where they need to focus more to reduce their CO2 emissions to meet the stringent BS6, CAFÉ and RDE emission norms
Higher gasoline heat of vaporization (HOV) can enable higher compression-ratio, direct-injection, spark-ignition engines by providing evaporative cooling that effectively increases fuel knock resistance. Methods to directly measure this fuel property in complex gasoline samples are not well developed. This study aimed to further improve a differential scanning calorimetry/thermogravimetric analysis (DSC/TGA) method to measure the total and partial HOV of gasoline. Ten market gasoline samples were chosen to have a wide range of properties to assess the method’s capability across the entire volatility range, with an emphasis on understanding how well the method captures the initial 10% of sample evaporation and how much sample is left unevaporated at the end of the experiment. Modifications to both the sample preparation/introduction method and the instrument itself were made to reduce initial sample losses, which included HOV measurements at 10°C and 5°C (in a cold chamber) and under
The Continuously Variable Transmission (CVT) is a widely adopted transmission system. The operation of a CVT is simple, but successfully foretelling the longitudinal motion of a vehicle that utilizes this transmission is sophisticated. As a result, different vehicles taking part in BAJA-SAE competitions were developed using various strategies to model the vehicle’s longitudinal dynamics and CVT operation. This article aims to provide a tool for obtaining a quantitative estimate of the longitudinal performance of a CVT equipped vehicle and for the selection of an optimal drive-train gear ratio for such a vehicle. To this end, this article proposes a novel, relatively simple, and reasonably accurate mathematical approach for modeling the longitudinal motion of a vehicle utilizing a CVT, which was developed by a novel integration of existing vehicle dynamics concepts. The proposed technique splits the longitudinal motion into three distinct phases - low ratio acceleration, shifting, and
This paper covers the mathematical modeling of governing equations for the coupled heat and mass transfer phenomena during adsorption and desorption. Also the main focus is given on the methodology for numerical simulation for solving these partial differential equations for carbon canister. A comprehensive literature review is presented to summarize the target requirements of allowed evaporative emission level of gasoline vapour in grams per day based on global standards like, EU6, EPA stage II enhanced, CARB LEVII, PZEV and SULEV. In order to meet these stringent emission norms, presence of carbon canister is mandatory. The simulation results are compared for the gasoline vehicle application at various climatic temperature conditions in India, in which the canister sizing vs allowable emission targets are summarized
In this work, a novel opposed piston architecture is proposed where one crankshaft rotates at twice the speed of the other. This results in one piston creating a 2-stroke profile and another with a 4-stroke profile. In this configuration, the slower piston operates in the 2-stroke CAD domain, while the faster piston completes 2 reciprocating cycles in the same amount of time (4-stroke). The key benefit of this cycle is that the 4-stroke piston increases the rate of compression and expansion (dV/dθ), which lowers the combustion-induced pressure rise rate after top dead center (crank angle location of minimum volume). Additionally, it lowers in-cylinder temperatures and pressures more rapidly, resulting in a lower residence time at high temperatures, which reduces residence time for thermal NOx formation and reduces the temperature differential between the gas and the wall, thereby reducing heat transfer. In this work, a custom 0D thermodynamic model was used to study the sensitivity of
Overall transmission error (OTE) of gear system has been a main focus of gear dynamics study. The input-output transmission error (TE) depends heavily on mesh phasing conditions. Only reducing loaded transmission error (LTE) of a single gear mesh is not enough to ensure good NVH performance in a multiple gear mesh system. In order to predict OTE during bevel gear design instead of just analyzing single mesh TE, a new bevel gear OTE calculation method will be presented in this study. Based on single mesh parameters including loaded and unloaded TE or mesh stiffness, the OTE of a differential gear set can be calculated without building a complete system model. The effect of phasing on system OTE shows that different tooth combination can have significant effect on dynamic performance which should be considered during design
The article examines quarter-car dynamics with the possible separation of its tire from the road. A set of nondimensionalized differential equations has been proposed to minimize the involved parameters. Time and frequency response investigation of the system has been analyzed insightfully considering tire-road separation. To measure the separation of the tire, a time fraction index is defined, indicating the fraction of separation time in a cycle at steady-state conditions. Minimizing the index is assumed as the objective of the optimized system. An actuator is applied to the vehicle suspension in parallel with the mainspring and damper of the suspension. Particle Swarm Optimization (PSO) is used to properly tune a Proportional-Integral-Derivative (PID) controller for the active suspension system excited by a harmonic excitation. To verify the effectiveness of the control proposed, the controlled result compared with a passive suspension system illustrates the design, achieving a more
A multi-dimensional model of the spark ignition process for SI engines was developed as a user defined function (UDF) integrated into the commercial engine simulation software CONVERGE™ CFD. For the present research, the model simulated spark plasma development in an inert flow environment without combustion. The UT model results were then compared with experiments. The UT CONVERGE CFD-based model includes an electrical circuit sub-model that couples the primary and secondary sides of an inductive ignition system to predict arc voltage and current, from which the transient delivered electrical energy to the gap can be determined. Experimentally measured values of the arc resistance and spark plug calorimeter measurements of the efficiency of electrical to thermal energy conversion in the gap were used to determine the thermal energy delivered to the gas in the spark gap for different pressures and gap distances. A novel feature of the presented model is that the thermal energy
This paper proposes an active chassis control strategy for an Eight-wheel drive/Four-wheel steering (8WD/4WS) combat vehicle, where only the first and second axles’ wheels are steerable, while the third and fourth axles’ wheels are non-steerable. Utilizing torque vectoring and differential braking control to improve its lateral dynamics at limit handling. Due to the non-linear characteristics of the tires and its friction limit, the vehicle may exhibit instable behavior during cornering maneuvers. It is well known that the tire longitudinal and lateral forces are shared, if longitudinal forces increased, slip ratio will increase and causing reduction in lateral forces that may cause the vehicle to drift out or spinning. Accordingly, the tires forces need to be optimally distributed based on vertical loads for each tire to prevent it from reaching the friction limit based on Friction Ellipse Theorem. In order to enhance vehicle maneuverability and stability under different road
Differential steering mode of distributed-drive articulated vehicle is proposed by using the characteristics of independent in-wheel motor. The compound steering system of articulated vehicle is composed of fully hydraulic steering system and differential steering. Several differential steering modes of articulated vehicle are presented, and the differential steering dynamic model of articulated vehicle is built to investigate the relationship of yaw moment and turning radius. The differential steering control strategy of articulated vehicle is studied while maintaining the vehicle in the stability domain. The energy consumption of articulated vehicle with differential steering is calculated by simulating vehicle single shift lane steering process. The simulation results show that the articulated vehicle with differential steering can reduce the energy consumption of hydraulic steering system up to 3.8%. It indicates that the articulated vehicle with compound steering system can
Engine research has increasingly focused on emission of sub 23 nm particulates in recent years. Likewise, current legislative efforts are being made for particulate number (PN) emission limits to include this previously omitted size range. In Europe, PN measurement equipment and procedures for regulatory purposes are defined by the particle measurement programme (PMP). Latest regulation drafts for sub 23 nm measurements specify counting efficiencies with a 65% cut-off size at 10 nm (d65) and a minimum of 90% above 15 nm (d90). Even though alternative instruments, such as differential mobility spectrometers (DMS), are widely used in laboratory environments, the interpretation of their sub 23 nm measurements has not yet been widely discussed. For this study, particulate emissions of a 1.0L gasoline direct injection (GDI) engine have been measured with a DMS system for low to medium speeds with two load steps. While the particle size distribution (PSD) at the higher load conditions
Recently, electric-powered vehicle such as HV, PHV, EV and FCV has been highly demanded and getting attention due to the increase of environmental-consciousness. Also, environmental regulations are getting more and more strict in many countries and regions. Then, environmental friendly vehicle is needed to be spread more and more than ever. As it is found in “TOYOTA Environmental challenge 2050”, Toyota will rapidly increase the number of new car sales of electric-powered vehicle towards 2050. This paper covers the rear wheel drive Q710 electric drive transaxle for 2nd generation MIRAI FCV. Toyota developed the transaxle for FCV (rear mounted) and for EV (front mounted) simultaneously and achieved coexistence of vehicle mountability and commonization of majority of the parts. This paper describes the hardware feature and the detailed technology which was adopted to Q710. In the 2nd generation MIRAI, the transaxle is mounted under rear floor and contributed to the improvement of
Direct-drive (DD) motor technology has been around for more than 40 years but its widespread adoption has happened only recently. Over the past few years, the cost differential between linear motor systems and traditional ball screw systems has halved
In this paper, an energy management method based on vehicular networking is proposed for the dual power sources fuel cell electric articulated vehicle. Vehicular networking includes a cloud computing center, which predicts the information of power demand for the real-time driving condition based on the history data analysis, and solves the energy management strategy for the dual power sources utilizing the Radau pseudospectral method (RPM). The global interpolation polynomial is used to approximate the state variables and control variables in the system. The derivative of the interpolation polynomial approximates the differential equation of the state variables in the dynamic equation. Further, the optimal control problem (OCP) is transformed into nonlinear problem (NLP) to be solved. The simulation result of the proposed strategy show that the capacity degradation of the fuel cell can be reduced while meeting the power output demand, which means the lifetime of the fuel cell could be
Connected and autonomous vehicles (CAVs) are regarded as the new generation vehicles. Nowadays, it is an ad-hoc worldwide research spot, especially the highly or fully CAVs. These high-level CAVs have not been put into the market yet. Since the innovation of CAV technologies keeps emerging, it is still a meaningful task to following the up-to-date public perceptions and expectations on these high-level CAVs. Using the Stated preference (SP) method, this study designed a questionnaire that included three kinds of questions, i.e., basic information, perceptions, and requirements of future potential users. The questionnaires were delivered by the social media, and finally 612 valid feedbacks were collected. Following a statistical analysis on the survey, a correlation analysis were applied to find the relationship between the individual backgrounds and their perceptions/expectations. Furthermore, this study used the Multinomial Logit (MNL) model to represent the users’ choice behavior in
This SAE Recommended Practice establishes equipment and procedures for the evaluation of the effectiveness and other performance characteristics of spark arresters or turbochargers used on the exhaust system of large engines normally used in a railroad locomotive, stationary power plant, and other similar applications. This document does not cover applications requiring flame arresting, exhaust gas cooling, or isolation from explosive gases. Two test methods are presented: a laboratory test using ambient air (cold test) and an engine test using exhaust gases (hot test). The hot test is preferred. Arresters tested by the provisions of this document can be expected to perform as tested when tilted no more than 45 degrees from their normal position. Test results from a spark arrester or turbocharger evaluated by the hot test can be applied to different engines of similar design, provided the data shows it to be effective in the applicable flow ranges. Certain design and performance
Advanced passenger vehicles are complex dynamic systems that are equipped with several actuators, possibly including differential braking, active steering, and semi-active or active suspensions. The simultaneous use of several actuators for integrated vehicle motion control has been a topic of great interest in literature. To facilitate this, a technique known as control allocation (CA) has been employed. CA is a technique that enables the coordination of various actuators of a system. One of the main challenges in the study of CA has been the representation of actuator dynamics in the optimal CA problem (OCAP). Using model predictive control allocation (MPCA), this problem has been addressed. Furthermore, the actual dynamics of actuators may vary over the lifespan of the system due to factors such as wear, lack of maintenance, etc. Therefore, it is further required to compensate for any mismatches between the actual actuator parameters and those used in the OCAP. This is done by
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