Mario Pisaturo

Multiple Constrained MPC Design for Automotive Dry Clutch Engagement

In this paper, a multiple model predictive controller (MPC) is proposed for the management of passenger car start up through dry clutch in automated manual transmission. Based on a high-order dynamic model of powertrain system, the feedback controllers are designed by using the crankshaft angular speed and the clutch disk angular speed as measured variables. Moreover, the MPC is developed to comply with constrains both on the input and on the output. The aim of the controller is to ensure a comfortable lockup and to avoid the stall of the engine as well as to reduce the engagement time. Numerical results show the good performance of the MPC with constrains in overcoming critical operating conditions. Comparisons with similar state-of-the-art works are also shown.

Modelling the cushion spring characteristic to enhance the automated dry-clutch performance: The temperature effect

The cushion spring plays an important role in an automotive dry-clutch system. It strongly influences the clutch torque transmission from the engine to the driveline through its non-linear load–deflection curve. Therefore, knowledge of the cushion spring compression behaviour is crucial to improve the gearshift performance in an automated manual transmission. Furthermore, the cushion spring compression behaviour is influenced by the temperature because of the frictional heat generation of the clutch facings with the flywheel and the pressure plate surfaces during the engagement phase. In this paper an analysis of the load–deflection curve, taking into account the thermal load to which it is subjected, of a typical passenger car cushion spring is proposed. Six temperatures, in addition to room temperature, were analysed to investigate how the cushion spring load–deflection curve depends on the temperature.

Improving the Engagement Smoothness Through Multi-Variable Frictional Map in Automated Dry Clutch Control

An Automated Manual Transmission (AMT) is directly derived from a manual one through the integration of actuators; then, development and production costs are generally lower than other automatic transmissions, while the reliability and durability are at highest level. For high class sport cars, vehicle dynamic performances and driving quality can be strongly improved with respect to automatic transmissions [1]. AMTs systems are generally constituted by a dry or wet clutch assembly and a multi-speed gearbox, both equipped with electro-mechanical or electro-hydraulic actuators, which are driven by a control unit, the transmission control unit (TCU). The operating modes of AMTs are usually two: semiautomatic or fully automatic. In both cases, after the gear shift command, the TCU manages the shifting steps according to current engine regime, driving conditions and selected program.In this transmission type the quality of the vehicle propulsion as perceived by the driver is largely dependent on the quality of the control strategies. Furthermore, sensitivity analyses on control schemes for AMTs have shown that uncertainties in clutch torque characteristic can severely affect the performance of the clutch engagement: modeling in detail the torque transmitted by the specific clutch architecture is a crucial issue in order to design robust engagement control strategies [2, 3 and 4].This paper aims at investigating the engagement performance of an actuated dry clutch by taking into account the inference of the pressure on the facing materials and the sliding speed. In fact, according to literature outcomes [5], the friction coefficient after a first rising behavior with the sliding speed shows an asymptotic value for a typical clutch facing; the same material exhibits a nearly linear dependence of the friction coefficient on the pressure.The simulations consider: reduced-order dynamic system for simulation of passenger car driveline, control algorithm, experimental maps of the n-D clutch transmission characteristic, and gear shift maneuvers in different operating conditions.The outcome of this analysis could provide valuable issues for designers of automated clutches and control engineers to overcome the well known poor engagement performances of open loop motion strategy of the throwout bearing where cost reason and complexity don’t permit the use of displacement sensor.Copyright

Automotive dry-clutch control: Engagement tracking and FE thermal model

The tribological contact under sliding condition in clutch facing surfaces during engagement manoeuvres is strongly affected by heat transfer occurring in the system. The frictional forces acting on contact surfaces produce mechanical energy losses which are converted in heat with ensuing temperature increase. In this paper, in order to estimate the error due by neglecting the effective spatial distribution of heat flux the Authors explored the thermal generation in a dry-clutch architecture during vehicle launch and up-shift manoeuvres. The results of the longitudinal vehicle dynamics have been used in a FEA to predict the temperature field during repeated clutch engagements on contact surfaces. Finally, simulations obtained by evaluating the same engagements manoeuvres but under different hypothesis, i.e. linearly dependable with disc radius and uniform heat flux have been compared. The results showed that the estimated thermal field in dry-clutch components changes by varying hypothesis. In such a way, this paper aims at providing useful references to control engineers in order to improve the dry-clutch transmissions performances.

Influence of the temperature on the dry-clutch engagement control in gear-shift manoeuvres

Recent evolutions in the developments of automated dry clutches and the associated control algorithms has led to a rapid diffusion of this transmission type. However the chosen control strategy affects strongly the passengers comfort and moreover the control action, particularly with regard to the clutch engagement, is influenced by the clutch torque characteristic model implemented in the Transmission Control Unit (TCU). Thus, to use a phenomenological approach to model the torque transmitted by the specific clutch architecture is a crucial issue in order to design robust engagement control strategies. Thus, to use a phenomenological approach to model the torque transmitted by the specific clutch architecture is a crucial step in order to design robust engagement control strategies. For these reasons this paper investigates the engagement performance of an actuated dry clutch by taking into account the thermal effects both on the cushion spring reaction and on the facing materials and consequently on the clutch torque characteristic. The outcome of this analysis could prove valuable for designers of automated clutches and control engineers to overcome the well known poor engagement problem. Index Terms- dry clutch, automated manual transmission, model predictive control, temperature effect.

Polyalkylene Glycol Based Lubricants and Tribological Behaviour: Role of Ionic Liquids and Graphene Oxide as Additives

The polyalkylene glycol (PAG) lubricants are widely used as gear, bearing and compressor oils in refrigerant systems. They are designed to provide outstanding benefits in terms of efficiency, long oil life, and equipment protection. These fully synthetic lubricants have been developed for use under operating conditions beyond the capabilities of other synthetic lubricants and mineral oils as their characteristic low pour point ensures excellent fluidity at low-temperature. On the other hand, the main drawback of PAG oils is the marked hygroscopicity, i.e., they absorb and bind moisture from the ambient air. In this paper, the results from tribological testing of PAG oil featuring 46 cSt at 40 °C with solid (graphene oxide) and liquid (ionic liquids) additives are discussed. Moreover, in this study the influence of absorbed moisture from ambient air has been investigated. Preliminary experiments with ball-on-flat setup by using reciprocatory tribometer tested the response of base oil PAG 46 blended with 1-Ethyl-3-methylimidazolium acetate or graphene oxide, alternatively. In such a way, the individual influence of each additive was questioned. Based on preliminary analysis, this research focuses on hybrid formulations to substantiate potential improvements of anti-friction and anti-wear PAG 46 performance over broad range of lubrication regimes. Experimental tests have been carried out by using rotational disc tribometer in ball-on-disc configuration. Additional experiments after samples exposure to ambient air and ensuing moisture absorption were carried out. The results highlight that in most cases limited absorbed moisture does not introduce detrimental effects on the tribological performances of the tested oil samples: indeed, water content could reduce wear of the sliding steel surfaces over the whole testing spectrum and in most of the cases the frictional energy dissipation.

Could electric motor in HEV assist vehicle launch and relief dry clutch from thermal damage

The Hybrid Electric Vehicles (HVEs) are reaching a wide diffusion both because the energy density and life of batteries increased in the last years with a decrease of their costs and because the reduction of air pollution is a very important issue, especially in big cities. This latter is one, or probably the main, reason that pushes the development of HEVs and electric vehicles (EVs).

Tribological Characterization of SiC and B4C Manufactured by Plasma Pressure Compaction

The objective of the present study was to assess the tribological properties and the wear behavior of silicon carbide and boron carbide ceramics, produced by the plasma pressure compaction sintering process. Reciprocating sliding tests were executed to evaluate the tribological behavior of silicon carbide and boron carbide. Samples of each material with distinct values of surface roughness Ra were tested. Wear mass loss, coefficients of friction and wear mechanism of the boron carbide and silicon carbide were evaluated by means of microscopes and an energy-dispersive spectroscopy probe. The coefficient of friction of the evaluated boron carbide was found to be 0.8, and the surface roughness affects only the starting transient, while for silicon carbide the steady-state value ranges from 0.5 to 0.8 depending on the roughness value Ra.

Simulations of Engagement Control in Actuated Dry-Clutch: Influence of Frictional Response of Facing Materials

This paper focuses on the simulation of clutch engagement behavior in automated manual transmissions (AMTs) to virtualize the vehicle start-up maneuver through implementation of the driveline model and the role of transmission control unit featuring different levels of knowledge regarding to clutch material frictional response. Simulation results underline the crucial requirement of accurate prediction of the frictional coefficient evolution in each clutch maneuver, particularly regarding to the interface temperature estimation to develop effective models and control algorithms.

Model predictive controller for the clutch engagement to limit the traction lag due to the engine torque build-up

Todays several algorithms are currently managed by the control units in passenger cars to deliver higher comfort level to vehicle driver and passengers. One route to smoother longitudinal dynamics as well as deliver higher safety is provided by the engine torque limiters and traction control. The drawback of such filters is that they bring in time delays which may give to the driver the feeling that the vehicle engine does not respond in a prompt way to her/his demand [1]. On the other hand, recent highly-supercharged engines suffer for inadequate engine torque rise when setting the vehicle in motion from stationary with fast accelerator request: this behaviour is related to fueling response, fuel-air ratio control, soot emissions regulation, etc. The goal of this paper is to design a feedback controller based on multiple Model Predictive Controller (mMPC) to manage the clutch opening/closing operations in a dry-clutch Automated Manual Transmission architecture. The controller aims at ensuring a comfortable vehicle launch by assuring a reduced engagement time and by maintaining the wheel slip at a desired value to have the maximum traction force. The simulations have been carried out by considering the engine dynamics as well as the delay ensuing engine torque build-up together to an imposed wheel slip in fast launch manoeuvre to prove the effectiveness of the proposed clutch control strategy and encourage the development of real-time routines for the testing in real-time environment.