Investigation on vibro-impacts of driveline system based on a nonlinear clearance element with time-varying stiffness and oil-squeeze damping

The transient vibro-impacts induced by clearance between the connected rotors in driveline system easily causes serious transient noise and vibration, especially between the gear teeth with backlash. To analyze the transient vibro-impacts of the driveline system excited by a step-down engine torque, a new piecewise nonlinear clearance element with time-varying stiffness and oil squeeze damping is proposed, and an 8 degree-of-freedom lumped parameters model with the new piecewise nonlinear clearance elements is established. The transient vibro-impact phenomena of the vehicle driveline during fast disengagement of the clutch are numerically simulated. Colormaps of angular acceleration and vibro-impact force shows the difference of frequency components from transient impact to stable tooth-meshing. The phase plane reveals the phenomenon of multiple impacts and rebounds in each transient impact, and shows the relationship between the relative contact displacement and velocity. The frequency responses of the angular velocity, angular acceleration and vibro-impact forces with time-varying stiffness and linear stiffness are compared respectively. Compared with the widely used clearance element with piecewise linear stiffness, the new nonlinear clearance element with the piecewise nonlinear time-varying stiffness can better reveal the transient vibro-impact responses between the driving and driven gears. Lastly, the transient vibro-impact results of driveline system are verified by the vehicle experiments.

Turbocharger surge behavior for sudden valve closing downstream the compressor and effect of actuating variable nozzle turbine

Surge is an unstable phenomenon appearing when a valve closing reduces the compressor flow rate. This phenomenon is avoided for automotive turbochargers by defining a surge margin during powertrain system design. This surge margin established with measurements in steady state testing regime limits the maximal engine torque at low levels of output. An active control of the compressor could reduce the surge margin and facilitate a transient compressor operation for a short time in surge zone. In this paper, an experimental study of the transient operation of a turbocharger compressor entering the surge zone is performed. Control of the turbocharger speed is sought to avoid unsteady operation using the variable geometry turbine (VGT) nozzle actuator. From a given stable operating point, surge is induced by reducing the opening of a valve located downstream of the compressor air circuit. The effect of reducing the speed of rotation by controlling the VGT valve is investigated, as this should lead to more stable compressor operation. The rotation speed of the turbocharger is controlled to avoid an unstable operating point using servo-actuator of variable geometry turbine. From a stable operating point, the surge appearance is caused by closing a butterfly valve downstream the air circuit of the compressor. The effect on the compressor rotation speed when the opening of variable geometry turbocharger valve is modified is studied. Measurements have been conducted for different control profiles of the VGT valve placed downstream the compressor. This article presents the means used to carry out these tests as well as the results of the measurements of the instantaneous signals of pressure, temperature, flow rate and rotation speed, allowing the analysis of the surge phenomenon.

Pengaruh variasi campuran bahan bakar pertamax dan bioetanol 99,9% terhadap torsi mesin bensin 4 langkah Tecquipment TD201

Bioethanol is ethanol made from plants such as cassava, sugarcane, sago, which are processed through hydrolysis, fermentation, distillation and dehydration processes. Lampung Province is one of the largest producers of cassava in Indonesia, with the total productivity of 5,451,312 tons in 2017, and 6,683,758 tons in 2018 or there was an increase of 22,61% compared to 2017. From this data, it is possible to produce bioethanol, where every 1 kg of cassava can produce 0,106 liters of bioethanol. This is what underlies this research to investigate the effect of blending bioethanol of 99% with pertamax and bioethanol on the engine torque. Blending bioethanol of 99% can homogeusly mix. The engine used in this study is a Kohler gasoline engine equipped with a VDAS (Versatile Data Accession System) instrument unit in determining the parameters of engine performance. The blending of bioethanol of 99% as big as 14% (E14) gave the highest value of torque at 1 rotation of dynamometer valve opening and engine speed of 2000 rpm.

INCREASING THE COMFORTABILITY OF THE VEHICLE DURING ACCELERATION BY IMPROVING THE DESIGN AND CONTROL METHODS OF THE MOTOR-TRANSMISSION UNIT

The derivative of acceleration with respect to time is used to evaluate and ensure driving comfort during acceleration and deceleration. Frequent and rapid changes in acceleration means frequent and rapid deformation, which can lead to the destruction of the load. The article proposes to minimize the amount of acceleration due to the rational choice of transmission ratios in intermediate gears and the law of changing the engine torque. The use of continuously variable transmissions allows you to solve the problem by choosing a rational law for changing the gear ratio of the transmission. The method of selection at the stage of car design of the maximum effective engine power and transmission ratio in top gear is proposed, taking into account the improved formula for calculating the aerodynamic resistance to motion. The required laws of change in the efficiency of the torque and engine power have been determined. The use of a continuously variable transmission allows the engine to operate at a constant high-speed mode and provides control over the acceleration of the car by changing the fuel supply. It is determined that the engine power expended on the movement with the adjustment of the acceleration of the car will be less than with unregulated acceleration if the exponent at the speed of the car, obtained experimentally, is less than one. Keywords: car; comfort; continuously variable transmission; motor-transmission unit; power; overclocking; aerodynamic resistance; gear ratio

Novel Mathematical Method to Obtain the Optimum Speed and Fuel Reduction in Heavy Diesel Trucks

In Mexico and many parts of the world, land cargo transport units (UTTC) operate at high speeds, causing accidents, increased fuel costs, and high levels of polluting emissions in the atmosphere. The speed in road driving, by the carriers, has been a factor little studied; however, it causes serious damage. This problem is reflected in accidents, road damage, low efficiency in the life of the engine and tires, low fuel efficiency, and high polluting emissions, among others. The official Mexican standard NOM-012-SCT-2-2017 on the weight and maximum dimensions with which motor transport vehicles can circulate, which travel through the general communication routes of the federal jurisdiction, establishes the speed limit at the one to be driven by an operator. Because of the new reality, the uses and customs of truck operators have been affected, mainly in their operating expenses. In this work, a mathematical model is presented with which the optimum driving speed of a UTTC is obtained. The speed is obtained employing the equality between the forces required to move the motor unit and the force that the tractor has available. The required forces considered are the force on the slope, the aerodynamic force, and the friction force, and the force available was considered the engine torque. This mathematical method was tested in seven routes in Mexico, obtaining significant savings of fuel above 10%. However, the best performance route possesses 65% flat terrain and 35% hillocks without mountainous terrain, regular type of highway, and a load of 20,000 kg, where the savings increase up to 16.44%.

Simulation research of the strength of an engine mount in an aircraft piston diesel engine

The article presents strength simulations of a mount for mounting the test engine. Mounted on a stationary test stand, this mount consists of external fixings, fixings to stabilize the engine and tubular elements as a truss. These tubular elements are pipes made of seamless black steel. The material of the truss is S235JR steel. The article examines three different versions of the mount: mount no. 1 - initial mount, mount no. 2 - mount after a modification of pipe arrangement, mount no. 3 - mount after a modification of pipe wall thickness. For each version of the mount and subsequent calculation steps, the same boundary conditions and results legend were assumed. All calculations were made in Catia v5 in the Generative Structure Analysis module. To reflect the conditions prevailing during the engine operation on the test bench, the following conditions as mount load were adopted: gravity from the engine mass as 1000 N; engine thrust as 5000 N, and engine torque as 227 Nm. First, the model was pre-calculated to check the influence of mesh size on the obtained results. 2 mm parabolic tetrahedral elements were used in a computational grid. All subsequent steps of the mount modification showed a positive effect of reducing the maximum stress values or their mitigation as dispersion over a larger area. The changes made it possible to eliminate potentially dangerous areas of stress accumulation points. The material used has a strength several times greater than the stresses occurring in the tested elements. It was found that no further modifications to the mount are required and it is possible to use the created geometry on the test stand.

Optimization Transmission Efficiency with Driver Intention for Automotive Continuously Variable Transmission under Slip Mode

This study proposes and experimentally validates an optimal integrated system to control the automotive continuously variable transmission (CVT) by Model Predictive Control (MPC) to achieve its expected transmission efficiency range. The control system framework consists of top and bottom layers. In the top layer, a driving intention recognition system is designed on the basis of fuzzy control strategy to determine the relationship between the driver intention and CVT target ratio at the corresponding time. In the bottom layer, a new slip state dynamic equation is obtained considering slip characteristics and its related constraints, and a clamping force bench is established. Innovatively, a joint controller based on model predictive control (MPC) is designed taking internal combustion engine torque and slip between the metal belt and pulley as optimization dual targets. A cycle is attained by solving the optimization target to achieve optimum engine torque and the input slip in real-time. Moreover, the new controller provides good robustness. Finally, performance is tested by actual CVT vehicles. Results show that compared with traditional control, the proposed control improves vehicle transmission efficiency by approximately 9.12%–9.35% with high accuracy.

Assessment of the stability of the gas-diesel automatic control system

Any steady-state operation of the engine is evaluated by qualitative and quantitative parameters. For internal combustion engines, the qualitative parameter is the speed of the crankshaft, and the quantitative parameter is the engine torque. There are functional dependencies between these parameters, the graphical representation of which is called speed characteristics. However, the transition modes of engines are much more complex than the established ones, especially in gas-diesel engines, where the relationship between the parameters of the engine and the characteristics of the gas supply units is quite complex, and the transition process is accompanied by a change in the parameters of its working process over time and is a dynamic mode.

Multi Time-Scale Engine and Powertrain Control for Autonomous Vehicles via Lagrange Multipliers

Connected and Autonomous vehicles (CAVs) have the ability to use information obtained via Vehicle-to-Infrastructure (V2I), Vehicle-to-Vehicle communication (V2V), and sensors to improve their fuel economy through predictive strategies, including velocity trajectory optimization and optimal traffic light arrival and departure. These powertrain control strategies operate on a slow timescale relative to the engine dynamics, hence assume that the engine torque production is instantaneous. This assumption results in a torque command profile that may lead to engine dynamics constraint violation, actuator saturation, poor tracking performance, decreased efficiency, poor drivability, and increased emissions. To address this issue, a supplemental controller based on an iterative hierarchical Model Predictive Control (MPC) is proposed in this paper. The constraint satisfaction is achieved through a novel two-way communication of the Lagrange multipliers. The proposed methodology is demonstrated on an autonomous Diesel semi-truck on two maneuvers. Compared to a traditional centralized approach, the proposed method achieves systematic constraints satisfaction with negligible effect on fuel economy, less than 1%, and significantly improved computation time, more than 10 times.