Browse Topic: Driveshafts
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 variability. A change to the conventional balancing process through a modified work-flow in the influence coefficient method, which is shown to give a more accurate process and, in addition, to reduce the balancing time, is outlined in detail. The results of balancing a large population of vehicles following the implementation of the modified process are then given and compared to a standard probability distribution.
This ARP applies to turbine engines that are to be used in helicopters. It provides the engine designer guide lines in achieving a satisfactory turbine engine drive shaft connection.
Accurate determination of driveshaft torque is desired for robust control, calibration, and diagnosis of propulsion system behaviors. The real-time knowledge of driveshaft torque is also valuable for vehicle motion controls. However, online identification of driveshaft torque is difficult during transient drive conditions because of its coupling with vehicle mass, road grade, and drive resistance as well as the presence of numerous noise factors. A physical torque sensor such as a strain-gauge or magneto-elastic type is considered impractical for volume production vehicles because of packaging requirements, unit cost, and manufacturing investment. This paper describes a novel online method, referred to as Virtual Torque Sensor (VTS), for estimating driveshaft torque based on Machine-Learning (ML) approach. VTS maps a signal from Inertial Measurement Unit (IMU) and vehicle speed to driveshaft torque. The unique advantage is that VTS does not explicitly rely on the first principles unlike other estimation methods. A robust mapping framework implicitly accounts for road grade, while compensating the effects of vehicle mass and drive resistance. Mapping coefficients are automatically and adaptively learned during selective drive conditions and continuously updated by means of Kalman filtering. VTS is implemented in a test vehicle with a P2 hybrid electric propulsion system for the assessment of robustness and sensitivity to drive conditions. The accurate estimate of driveshaft torque from VTS is utilized to determine the characteristics of a wet clutch which is employed for cranking an internal combustion engine during EV-HEV mode transition. VTS demonstrates a ML-based data-driven solution to the accurate determination of driveshaft torque and wet clutch behaviors. VTS framework can be readily extended to broader applications, including battery electric vehicle, with additional capabilities such as wheel torque estimation during braking and steering.
With the advent of BS VI regulations, automotive manufacturers are required to innovate the powertrains, fuel systems, exhaust and its after treatment systems to meet the regulatory requirements. The exhaust regulations can be met either by reducing the exhaust gases being generated by the engine (attacking the source) or by treating the exhaust gases in after treatment devices. The choice of the opted system varies with the manufacturer. The after-treatment devices such as catalytic converters are generally mounted in the engine compartment to take advantage of high temperature of exhaust gases to yield the reactions. Such an arrangement imposes a lot of thermal load on the peripheral components such as gearshift cables, bearings, oil seals, driveshafts etc. Thermal shields or thermal sleeve are used to address thermal issue and to protect transmission components. System level validation test requirement of transmission need to be re-visited considering change in environmental condition of operation. Also, component level test related to thermal sleeve and thermal shield need to be included in the component level validation plan. This paper discuss different validation requirement derived to validate the thermal sleeve and thermal shield from performance and durability point of view at system level and component level. Effect of parameters such as air gap, rotational speed (for component such as driveshaft), temperature of source, air draft, presence of dust and dirt in the operating environment etc for the derivation of test criteria are also discussed in detail. This paper also explains the test setup requirements for the thermal data acquisition during validation test. Proposed validation process help to get early feedback during the development and reduce the overall development time by avoiding requirement of complete validation of affected aggregates at vehicle level.
Calibrating a vehicle’s powertrain for dynamic operation needs to focus on efforts to mitigate the risks of thermal overload which may arise in the stator or rotor components of an e-motor. Risks also may arise for expected NVH or durability targets, with torque and torque “oscillations” acting as primary sources for the vehicles’ NVH behavior. Both topics, temperature measurement of stator and rotor as well as dynamic torque measurements of the powertrain’s drive shaft are addressed with examples demonstrating the sensors applications in normal test bed and vehicle configurations.
The driveshafts can be an important contributor to vehicle interior noise including low-frequency (booming) noise where the vibrations, originating in the powerplant, travel to the vehicle body through the driveshafts. A suitable Key Performance Indicator (KPI) for the driveshaft performance is the transmissibility, which is an output/input acceleration ratio and can be used to describe the amount of vibration transferred from the inboard to the outboard joint of the driveshaft. This paper introduces a simple physical model of the driveshaft transmissibility able to support the development and evaluation of the driveshaft and to estimate the effectiveness of countermeasures such as a dynamic damper. The model is validated through comparison with on-vehicle measurements. The proposed approach offers ease of use, low computational cost and clear relation of the measured transmissibility with the system’s physical properties. Good accuracy can be obtained for the booming noise range, especially if the driveshaft attachments are suitably represented through an equivalent stiffness that can be easily obtained from test or computer-aided engineering (CAE). The simplifications in the proposed model may limit the practical range of applicability. Nonetheless, for the low frequency problems considered, it can support the component and countermeasure development, reducing the need for prototype evaluations.
The breaking torque is an essential property that identifies the strength of driveshafts under high torque loads. In the breaking torsion test, the constant velocity joint of the driveshafts is usually loaded slowly at a very slow rotating speed under a specific joint angle until it breaks. Under different joint angles, the Rzeppa type constant velocity joint, namely ball joints (BJ), will break at different positions and with different torques. Common results of fracture position include the shaft of the outer race, the shell of the outer race, and the cage column. Simultaneously, the plastic deformation caused by compressive stress occurs at the specific position of the ball track and the cage. In order to analyze the failure reason of the ball joint under a larger joint angle, the quasi-static finite element simulations and test methods are used to analyze the damage caused by stress distribution based on material properties. At the same time, through simulation analysis, the displacement and contact of internal parts can be used to find out the reasons for the imbalance of internal parts.
A ball joint is an important component of the automotive drive shaft system, as well the contact stress inside the ball joint is an important optimization goal in the design of ball joints. At present, the analysis of the contact stress inside the ball joint mainly focuses on the static contact stress analysis. The static contact stress analysis, however, cannot reflect the change of the contact stress inside the ball joint. In order to analyze the contact stress of the ball joint more effectively, a hybrid flexible and rigid bodies dynamics (HFRBD) model of the ball joint for studying the dynamic contact stress inside the ball joint is proposed. In the HFRBD model, the balls are regarded as the rigid body, while the cage, the inner race and the outer race are regarded as the flexible body. The contact parameters of the contact pairs in the model are determined on the basis of Hertz contact theory. Through the destruction test of the ball joint and the numerical example, the effectiveness of the HFRBD model and the method for the analysis of the dynamic contact stress inside the ball joint is verified. Based on the proposed HFRBD model, the stress distributions of the cage, the inner race and the outer race under different rotation angles are analyzed subsequently. The presented modeling and analysis methods for the dynamic contact stress inside the ball joint in this paper have an important reference for the design of a ball joint.
During the operation of the automotive drive shaft system, the ball-type universal joint will generate a secondary torque, which will affect the torque transmission of the automotive drive shaft system and the comfort of the automobile. Under the influence of the internal friction of the ball-type universal joint, the secondary torque generates a torque component on the plane where the working angle is located and the plane perpendicular to the working angle. To effectively calculate and analyze the secondary torque, this paper establishes a multi-body dynamic model of the ball-type universal joint. At the same time, the secondary torque of the ball-type universal joint is measured by the NVH multi-function test bench, which verifies the validity of the multi-body dynamic model. In order to improve the analysis efficiency of the secondary torque, a proxy model of the secondary torque of the ball-type universal joint is established based on the multi-body dynamic model. Through the proxy model, the influence of contact angle, conformity value, offset, friction coefficient, and the interference fit between ball and cage window on the secondary torque is analyzed. Using the global sensitivity analysis method of partial derivatives, the sensitivity analysis of the proxy model is carried out, and the degree of influence of each influencing factor on the secondary torque is further determined. According to the results of sensitivity analysis, this article gives measures to optimize the secondary torque.
The adequate dimensioning of drive train components such as gearbox, clutch and driveshaft presents a major technical task. The one of manual transmissions represents a special significance due to the customer’s ability of inducing high force, torque and thermic energy into the powertrain through direct mechanical interconnection of gearstick, clutch pedal and gearbox. Out of this, the question about how to capture behavior and strain of the components during real operation, as well as their objective evaluation evolves. Furthermore, the gained insights must be considered for designing and development. As a basis for the examination, measuring data from imposing driving tests are adduced. Therefore, a trial study has been conducted, using a representative circular course in the metropolitan area of Stuttgart, showing the average German car traffic. The more than 40 chosen drivers constitute the average driver in Germany with respect to age, gender and annual mileage. The used vehicle is equipped with high resolution data acquisition in order to determine inner systemic variables such as oscillation of the drivetrain, clutch slip, engine and wheel torque as well as outer variables such as pedal stroke and acceleration during the shifting process, which the driver controls. Misuse aspects resulting in increased wear or even component damage as well as comfort-related aspects are collected and consulted for further development. In the context of this study the collected measurement data are analyzed in detail. On basis of this analysis, an evaluation of the shifting processes during real operation is conducted and presented by use of objectified characteristic variables. Finally, the evaluations of different shifting processes are opposed. With the help of t-SNE and cluster analysis as a classification method on basis of a machine learning algorithm, different types of drivers can be worked out and described in detail using the determined characteristic variables.
During the operation of the ball joint, its service life and transmission efficiency are affected by the internal friction. Taking the ball joint as the research object, based on fractal theory, the friction between the steel ball and the raceway inside the ball joint of an automotive drive shaft system is studied in this paper. During the analysis, the friction between the steel ball and the arc raceway is regarded as the friction between a sphere and an arc raceway surface. In order to describe the friction state more accurately, this paper proposes a correction coefficient to modify the distribution function of contact asperities in the plane, and obtains the distribution function of contact asperities between the sphere and the arc raceway surface. The correction coefficient is related to the load, the size parameters and the material parameters of the steel ball and the raceway. Then based on the modified distribution function, the fractal models of the friction coefficient, the tangential force (the friction force) and the normal contact load between the steel ball and the raceway are established. Finally, the correction coefficient is verified by the finite element model, while the relationship between the correction coefficient and the load, the relationship between the friction force and the normal contact load, and the relationship between friction coefficient and fractal parameters are analyzed through numerical examples.
To study the generated axial force (GAF) of the drive shaft system more accurately and effectively, this paper introduces the interval uncertainty into the research focusing on the GAF. Firstly, an interval uncertainty model for calculating the GAF is proposed based on the Chebyshev polynomials and an analytical model of the GAF. The input torque, the articulation angle, the rotation angle of the drive shaft system, the pitch circle radius (PCR) of the tripod joint and the friction coefficient are regarded as interval variables. Secondly, the upper and lower bounds of the proposed GAF model under interval uncertainty parameters are calculated quickly with the vertex method. Then the interval uncertainty optimization of the GAF under uncertainty parameters is performed. The upper bound of the response interval of the GAF is taken as the optimization object. Finally, the proposed model is verified by experiments, while the interval uncertainty analysis and optimization of the GAF are carried out through a numerical example.
Increased focus on fuel efficiency and vehicle emissions has led the automotive industry to look into low weight alternative designs for powertrain system components. These new design changes pose challenges to vehicle attributes like NVH, durability, etc. Further, the requirement of high power applications produces even more complexities. The present work explains how a potential design change of half shafts driven by a desire to reduce weight and cost can lead to NVH problems caused by half shaft resonances and explains how using multiple dynamic vibration absorbers can solve the issue to meet customer expectation while improving efficiency. With the aid of Finite Element Analysis (FEA) & optimization software, interactions between multiple DVA’s on a system was understood and optimal damper parameters for effective damping was identified. The final DVA design was tested and verified on the vehicle for optimal attribute performance.
The knowledge of mechanical behaviour of material is vital for durability prediction and attending initial project requirements. Through the experimental evaluations is possible to measure this behaviour and use it as input in numerical simulations. Temperature changes considerably static and dynamic mechanical properties of materials, particularly in elastomers. This study was motivated to predict the durability under several working temperatures of center bearings rubber cushion of driveshafts that needs to achieve prespecified stiffness and durability parameters. Standardized specimens were tested in fatigue for experimental investigation of the rubber compound. Durability tests were performed in the final product sample and compared with tests performed in standardized specimens. It was concluded that this approach produces accurate results for fatigue predictions and provided useful equations for practical design applications and reducing product validation time.
A system of passive balancing devices could potentially be used to suppress vibrations in helicopter tailrotor driveshafts. Passive balancing devices for rotary shafts consist of masses restricted by concentric guides about the shaft axis. At supercritical shaft speeds, the balancing masses automatically adjust to counter imbalance due to uneven load distribution. The problem is highly nonlinear and requires comprehensive modeling to achieve satisfactory prediction of the balancing behavior. A frequency-scaled tailrotor driveshaft test rig was fabricated to test the performance of a passive balancing device and to validate a comprehensive model. The model includes balancing mass collisions and balancing mass interaction with the balancer track through friction. Experimentally, the passive balancing device on average reduced driveshaft transverse vibrations by 62% at steady-state. Models available in the literature predicted vibration amplitudes to within 68% of the experimental values. The new balancing model improved the prediction of shaft vibration amplitudes by a factor of 3.9 when compared to published models (18% vs. 68%). This suggests that friction and mass collisions cannot be ignored in passive balancer modeling and that passive balancing is a viable solution for suppressing driveshaft vibrations.
Driveshafts are composed of a transmission side joint, wheel side joint, and shaft which connect the two joints. The Rzeppa type constant velocity joint (CVJ) is usually selected as the wheel side joint of a drive shaft for front wheel drive automobiles. Due to recent needs of fuel efficiency and lighter weight for vehicles, it is necessary to reduce the joint size and improve the efficiency of a CVJ. In order to reduce the weight, solving tribology details for long life under high contact pressure is an important issue for developing a CVJ. It is difficult to understand the characteristics of a contact surface, such as relative slip velocity or spin behavior, because the outer race, inner race, cage, and balls, act complicatedly and exchange loads at many points. Meanwhile, after joint endurance tests, ball spalling marks at pole of the ball are sometimes observed. Simulating ball rotational behavior and solving the formation mechanism of such phenomena could contribute to joint durability and joint efficiency improvement. In this paper, ball rotational behavior, is simulated using a multibody dynamics approach including stick slip friction force model that is more accurate than previous. This model enables simulation of ball angular velocity. Through multipoint measuring and graphical analysis, the experiment proves an error of 15% in the simulation result.
Thermoplastic composite driveshafts have demonstrated a 35% weight reduction and over 150% greater post ballistic damage survivability over legacy aluminum designs. This was achieved through the joint efforts of Automated Dynamics, NAVAIR, SURVICE Engineering, UTAS, and Sikorsky under a Small Business Innovation Research (SBIR) Phase II effort. An evolution of previous efforts, this paper describes subsequent work to optimize laminate architecture, materials, and structural qualifications to meet new performance requirements. SURVICE Engineering optimized the design of the driveshafts to meet new performance requirements supplied by Sikorsky. Automated Dynamics used its recently updated additive manufacturing process using high performance thermoplastic composites to rapidly manufacture prototype driveshafts. UTAS assembled and tested the composite driveshafts. The end goal is a high performance composite driveshaft that is a drop-in replacement for the legacy aluminum driveshaft. Driveshafts were tested to advance the program to a Technology Readiness Level (TRL) of 6.
Testing was recently performed on a new tail rotor drive shaft (TRDS) technology developed under the Future Advanced Rotorcraft Drive System (FARDS) program. The FARDS TRDS operates above its third critical speed, has a curved shaft centerline, and utilizes a novel damper design, advanced materials, and advanced manufacturing technologies. This TRDS design allows for a reduction from seven shaft segments to only two, which reduces system weight and cost. The endurance, low cycle fatigue, and high cycle fatigue testing performed on this drive shaft design was successful, and demonstrated a Technology Readiness Level (TRL) 6.
ABSTRACT A recent Phase II SBIR program focused on improving the survivability of driveshafts in rotorcraft applications while decreasing their weight. Thermoplastic composites were identified as a candidate material for achieving the goals of the program and a design was developed utilizing data from many previous sources and designs. Driveshafts were manufactured and validated against predicted static torque loads after withstanding a ballistic impact. The shafts showed a significant improvement in post-damaged strength over the legacy aluminum design with a weight reduction greater than 30%, exceeding all program goals. Automated Dynamics utilized recent process advancements in manufacturing both test coupons and driveshafts. This process takes advantage of unique aspects of in-situ composite consolidation to improve the bond affected between subsequent plies of pre-impregnated fiber reinforced thermoplastic materials on a continuous basis. Coupon test results demonstrated a 52% reduction in void content and greatly improved mechanical properties, further improving the performance over aluminum and thermoset composite driveshafts.
The increased demand in fuel economy and the reduction of CO₂ emissions results in continued efforts to downsize engines. The downsizing efforts result in engines with lower displacement as well as lower number of cylinders. In addition to cylinder and displacement downsizing the development community embarks on continued efforts toward down-speeding. The combination of the aforementioned factors results in engines which can have high levels of torsional vibrations. Such behavior can have detrimental effects on the drivetrain particularly during the development phase of these. Driveshafts, couplings, and dynamometers are exposed to these torsional forces and depending on their frequency costly damages in these components can occur. To account for these effects, FEV employs a multi-body-system modeling approach through which base engine information is used to determine optimized drivetrain setups. All mechanical elements in the setup are analyzed based on their torsional behavior. Bending and axial vibration are considered in the analysis as well. During the early stages of engine development, very little information is available to ensure proper drivetrain layout. To ensure highest possible usefulness of the modeling tool, the developed algorithms can function with very limited input data. The moments of inertia, stiffness, and dampening of the five major groups - crankshaft, piston assembly, flywheel, driveshaft, dynamometer - are required to ensure successful processing. A large database with known components can support the process in case precise target data is not available. Cylinder pressure information allows to further increase the accuracy of the results. All available information is processed and the natural frequencies and Eigen modes are determined. This basis allows further optimization of the drivetrain through modifications of the critical parameters of flywheel and driveshaft. The optimized result allows robust and reliable engine testing under all operating conditions.
Driveshafts are one of the most important components in power-train system in vehicle as it transfer torque generated from engine to wheels in high speeds. As a driveshaft is in rotating condition vibration problems can be observed by resonance or external force. The generated vibration problems in vehicles cause discomfort to drivers whenever they are driving. To solve these problems, there have been many attempts to control such generated vibration in vehicle. In this study, vibration control system for driveshaft has been proposed to reduce the generated vibration. The smart damper for the system is designed considering to be implemented in driveshaft with quick response and a compact size. The damper is consists of electromagnets so it can response relatively quickly compared to other damping system. When a driveshaft reaches to its natural frequency, vibration control system with the damper is activated to minimize the vibration as it shifts its natural frequency region. The test results show that the magnitude of vibration is reduced and the natural frequency region is shifted with quick response as the control system is activated.
Greek mythology tells of the inventor Daedalus using wings of his own fashioning to escape from imprisonment on the island of Crete. In 1988, a similar adventure was launched, though in this case, carbon-fiber composites, gears, and driveshafts were featured instead of wax and feathers.
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