Browse Topic: Flywheels

Items (106)
Abstract The concept of making a two-wheeled self-stabilizing vehicle can be a possibility soon. These vehicles use control moment gyroscopes (CMGs) to provide enough torque for the vehicle to prevent it from rolling and falling to the ground. CMGs can be used with different numbers and configurations. In this article, the aim is to offer a design procedure for a double gyroscope system, which can be used for any two-wheel vehicle to be self-stabilized. The procedure is based on using optimization algorithms in reaching the optimum double gyroscope configuration for a certain two-wheel vehicle to reach a zero-degree roll angle in the least time possible, which is the novel part of the procedure. A design procedure for a double gyroscope with the yaw axis as a spinning axis for a two-wheel vehicle is offered. This procedure has been tested for both a small two-wheel robot and a two-wheel enclosed vehicle. The research method started with a presentation of motion equations, followed by a discussion of the use of the PID cascade controller and its tuning process. Also setting up the simulation and finally using the gradient descent method of optimization with both the sequential quadratic programming (SQP) and the interior point algorithms to optimize the simulation results to achieve the optimum design. The simulations were carried out using an initial roll angle of 15°. Before optimization, the small two-wheel robot reached 0° roll angle in nearly 5 seconds at 2000 RPM flywheel spinning velocity and the two-wheel enclosed vehicle reached 0° roll angle in nearly 2.5 seconds at 4000 RPM flywheel spinning velocity. After optimization for the same spinning velocities the small two-wheel robot reached 0° in nearly 2 seconds but the enclosed two-wheel vehicle did not show a significant improvement with the results due to the good performance of the initial design of the vehicle.
Aboelsaoud, MostafaTaha, Ahmed AbdelsalamMabrouk, Mohamed YasserAboelazm, MohamedElgamal, Hassan
Investigation and Improvement of a Bouncing Torsional Vibration in Automotive Dual Mass Flywheel by Combining Testing and 1D CAE Modeling Approach2019-01-15566/5/2019
Dual mass flywheel (DMF) is a well-known isolation system for vehicle drivetrain. DMF has two typical elastic energy storage systems: long travel arc springs and in-series spring units (including two or more springs) and sliding shoes connected in series. DMF has such complex nonlinear characteristics as torque-dependent torsional stiffness and rotational speed-dependent hysteresis friction due to its dependency of centrifugal force that is applied to components and radial force of springs. Because of this complexity, sub-harmonic vibration (SHV) may occur under certain circumstances, such as under light-load and high-rotational conditions. In general, since SHV’s frequency is 1/2 or 1/3 of the engine’s combustion frequency and may cause human discomfort, DMF must be designed robust against such nonlinear vibration. In this paper to reduce the SHV occurrence and to show a more robust design indicator, the SHV causing the mechanism is researched by testing and 1D CAE modeling. In detail, DMF interior behavior in high-speed rotation is clarified with high-speed cinematography on a test bench, and high-resolution relative torsional angle of DMF is obtained by evaluating the actual vehicle with a conventional four-cylinder gasoline engine, which is equipped with in-series spring unit type DMF. As a result, bouncing torsional vibration (BTV) might occur when sliding shoe and secondary-side driven flange contact each other, and that is triggering the SHV excitation. 1D CAE model, whose development is based on the tested mechanism, is verified since the substantially same BTV and SHV occur between tests and simulation results. According to 1D CAE, highly sensitive parameters and ideas for reducing SHV can be found with sensitivity analysis of the physical DMF parameters. The effect of those parameters was confirmed with vehicle tests.
Yamakaji, YoshihiroYoshimoto, DaisukeTsujiuchi, NobutakaIto, Akihito
Characteristics of Bending Stress with Whirling at the Rear End of a Crankshaft in an Inline 4-Cylinder High Speed Diesel Engine2019-01-15926/5/2019
As engines become lighter and achieve higher output to meet carbon dioxide emissions targets, it becomes more challenging to design a crankshaft that is both lighter and capable of handling higher loads. Therefore, it is necessary to understand the characteristics of forces imposed on the crankshaft, and the mechanisms by which stresses are created in the crankshaft. This paper describes the characteristics of bending stresses measured on the rearmost crank pin fillet of a crankshaft. Two basic crankshaft resonant modes are described. Forward crankshaft whirl then has the effect of increasing the system natural frequencies by the stiffening effect, while reverse whirl reduces the system natural frequencies by the softening effect. The effect of whirl grows with increasing engine speed. This results in what appears to be four crankshaft natural frequencies rather than two. The four resonances appear at all non-zero engine speeds. The influence of flywheel mass on the stresses and natural frequencies is also described. It is shown that the bending stress in the crank fillet is proportional to the radial force acting on the crank pin. It is also shown that the direction of whirl affects the amplitude of stress imposed by the radial crank pin force, and that the effect of whirl becomes larger as the flywheel inertia is increased. Because increasing engine speed causes more whirl force and moment, engine speed has an influence on bending stress amplitude. Finally, the paper explains why the ratio of crank stress amplitude to radial force varies as a function of the rotational direction of whirl.
Kobayashi, Shinichiro
Development of Horizontal Water Cooled Diesel Engine to Achieve High Power Density2018-32-006410/30/2018
The horizontal water cooled diesel engine has a structure including all component parts such as a fuel tank that are necessary to drive engine, and is often a single cylinder engine. It is mounted on many applications such as power tiller and water pump because of high general versatility of installing owing to belt drive. It has a simple structure because of single cylinder, and is active mainly in Southeast Asia. At the same time, the market requires this type of engine higher power while a compact structure is also required from the viewpoint of easy to supply and use. In other words, “High power density” that is improving the output per body size has been required. We have responded to the demand of “High power density” by increasing output without changing the engine size. In order to keep the engine size, we have been enlarging displacement by using our peculiar stroke-up expertise and original bore-up contrivance. In addition to those techniques, we introduced analytic technology for early approach to optimal solution. While we had used deep bowl combustion chamber for emphasizing medium and low speed torque, we adopted shallow dish combustion chamber because we shortened the compression height of piston for stroke-up. We utilized combustion analysis so as to approach optimal solution early because we have no base data of shallow dish combustion chamber. In addition, we used stress analysis to optimize the hardening of crankshaft. As written above, by incorporating analytic technology in addition to conventional development methods, we have been supplying correct size engines speedily in response to requirement of market. In this paper, we introduce the techniques that we adopted in order to realize the high power density.
Komai, YoshinobuTakashima, YusukeFujiwara, TsukasaOkamoto, HisaoKawahara, Minoru
A 1-D Simulation Model for Analysis and Optimization of Gearbox Rattle Noise2017-01-17806/5/2017
In the design or match process of vehicle powertrain system, gearbox rattle is a common NVH problem which directly affects passengers’ judgment on the quality and performance of vehicle. During the development process of a passenger car, prototype vehicles have serious gear rattle problem. In order to efficiently and fundamentally control this problem, this work first studied the characteristics and mechanisms of the gearbox rattle. The study results revealed that the torsional vibration of powertrain system was the root cause of gearbox rattle. Then a simulation model of the full vehicle was built with the aid of Simulink® toolbox, which is a graphical extension to MATLAB® for modeling and simulation of variety of systems. With this model, the sensitivity analysis and parametrical optimization were performed, and the simulation results indicated that the dual-mass flywheel (DMF) was the best measure to control the rattle. In order to verify this conclusion, this work developed a DMF system and embedded it into the powertrain of the prototype vehicle. Both subjective evaluation and the objective measurement on the vehicle indicated that the gearbox rattle problem was successfully solved. The main significance of this study is to establish an effective and easy approach to analyze and control the gearbox rattle. The indicative conclusions of this work could be referred by NVH engineers in the early phase of vehicle development.
Xu, Yong
Tribodynamics of a New De-Clutch Mechanism Aimed for Engine Downsizing in Off-Road Heavy-Duty Vehicles2017-01-18356/5/2017
Clutches are commonly utilised in passenger type and off-road heavy-duty vehicles to disconnect the engine from the driveline and other parasitic loads. In off-road heavy-duty vehicles, along with fuel efficiency start-up functionality at extended ambient conditions, such as low temperature and intake absolute pressure are crucial. Off-road vehicle manufacturers can overcome the parasitic loads in these conditions by oversizing the engine. Caterpillar Inc. as the pioneer in off-road technology has developed a novel clutch design to allow for engine downsizing while vehicle’s performance is not affected. The tribological behaviour of the clutch will be crucial to start engagement promptly and reach the maximum clutch capacity in the shortest possible time and smoothest way in terms of dynamics. A multi-body dynamics model of the clutch system is developed in MSC ADAMS. The flywheel is introducing the same speed and torque as the engine (represents the engine input to the clutch). The hydraulic pressure is applied behind the piston to initiate the engagement. The angular motion of the plates is supported by friction torque between the plates and friction linings. The conjunctions between paper-based linings and steel plates are designed to be dry. Friction (the most significant tribological feature of the linings in torque transmission) is measured in a pin-on-disc tribometer and mapped into the dynamics model in MSC ADAMS. The pin-on-disc tribometer is able to capture the variation of friction coefficient with contact pressure and sliding velocity. The surface topography is obtained experimentally to examine the consistency of surface properties. The normal pressure and tribology of the contacting components determines the engagement time, clutch capacity and dynamic behaviour of the clutch.
Dolatabadi, NaderRahmani, RaminTheodossiades, StephanosRahnejat, HomerBlundell, GuyBernard, Guillaume
NVH Performance Improvement Study Using a Dual Mass Flywheel (DMF), Inertia Ring Type Tuned Torsional Vibration Damper (TVD) and Single Mass Flywheel (SMF) in a Front Engine and Rear Wheel Driveline Architecture2017-01-17526/5/2017
At present, a Dual Mass Flywheel (DMF) system is widely known to provide benefits on driveline induced noise, vibration and drivability over a Single Mass Flywheel (SMF). A well-tuned DMF provides nice isolation of torsional vibrations generated in periodic combustion process of automobile IC engines. Similarly, a torsional vibration damper mounted on driveline component reduces the torsional excitation and results a lower torsional vibration at driveline components. Noise and vibration issues like boom noise and high vibrations at low engine RPM range drive are often resulted due to high engine firing order torsional excitation input to the driveline. More often, this becomes one of the most objectionable noise and vibration issues in vehicle and should be eliminated or reduced for better NVH performance. A 4 cylinder, 4 stroke small diesel engine equipped with SMF is found to have high engine firing order torsional excitation. The engine is chosen to carry out a comparative study of NVH performance improvements by using a DMF, SMF and TVD in standalone and possible combinations in a front engine and rear-wheel-drive vehicle. A detailed study has been carried out in terms of packaging and hardware between DMF and SMF to make the DMF to be able to work in the engine initially fitted with SMF. The paper is categorized in three segments. First section describes the details of a standard DMF and TVD build configurations and its associated NVH aspects. Second section describes the feasibility study of DMF to be able to work in the engine and in a rear wheel driveline architecture. The final section describes the NVH performance comparison of DMF, SMF and TVD.
Gupta, KapilChoudhary, ArunBidre, Rakesh
Critique of Torsional Vibration Damper (TVD) Design for Powertrain NVH2017-26-02171/10/2017
Crank train torsional vibration is an important aspect for design and development of Powertrain for NVH refinement and durability. Crank train torsional vibration parameters like angular acceleration of flywheel or twist, depends upon various design parameters like geometry of crankshaft, mass of flywheel, stiffness of clutch, mass of pulley etc. It also depends upon engine operating conditions like engine speed, engine load, combustion peak pressure and combustion pressure variation etc. Most of these parameters are decided by engine power, torque, engine architecture and packaging constraints. Addition of torsional vibration damper (TVD), which works on the principle of tuned dynamic absorber, is commonly deployed design solution to control the torsional vibrations as well as stresses (to improve durability of crank train) induced in crank train assembly at specified modal frequency. This paper is critique study, which emphasizes on importance of accurate tuning of TVD frequency to make it work for NVH & durability improvement rather than deterioration. It also emphasizes whether crank train really need TVD or not. As its principle of working calls for, it needs to be tuned at right frequency to reduce the torsional vibration peak/twist at particular frequency. Any deviation in tuning of TVD frequency will force it to act as additional mass rather than tuned absorber. This will lead to the lowering of torsional frequency of crank train assembly and can shift the crank train assembly mode to critical operating frequency range of engine.
Yadav, Arvind KumarBirari, MayurBijwe, VilasBillade, Dayanand
A New Two Cylinder Diesel Engine Family for Off-road in Naturally Aspirated and Turbocharged Intercooled Versions2016-01-233510/17/2016
The design and development of a new four-stroke two-cylinder diesel engine family of 1.29 litre capacity for off road are discussed. The engine is in naturally aspirated and turbocharged and intercooled versions and rated from 11.9 kW/1500 rpm to 25.7 kW/2500 rpm. The engines were tuned for air and fuel flows, air utilisation, fuel air mixing, performance and emissions at steady state at a development lab and later certified in national labs. The high altitude capability of the TCIC was checked using a model. The engines rated at less than 19 kW satisfy India Generator set and off road norms of India and Europe equivalent to USTier4 standard, and at higher ratings, standard equivalent to US Tier4-interim. In the second part of the paper, the design of coolant and oil pumps, oil cooler for TCIC engine and the piston with steel oil control ring are discussed. The higher loaded TCIC engines use fillet hardened crankshafts of chromium molybdenum steel. The crankcase integrated with the flywheel housing and the timing case at the front, in conjunction with a cast iron sump makes the engine rigid against torsion and bending in an agricultural tractor. The firing order 0°-360° with the two pistons moving in phase allows lower cyclic irregularity and a light flywheel as well as turbocharging. The resultant primary reciprocating inertia force is neutralized by a counter-rotating balancer shaft and the fluctuations in crankcase pressure are taken care by a valve in the breather to avoid oil carry over.
Lakshminarayanan, P. A.Senthilkumar, P. K.
Analysis of Dual Mode Continuously Variable Transmission for Flywheel Energy Storage Systems2016-01-11774/5/2016
There are different types of energy storage devices which are used in today’s hybrid and electric vehicles. Batteries, ultra capacitors and high speed flywheels are the most commonly used ones. While batteries and supercapacitors store energy in the form of electric energy, the flywheel (FW) is the only device that keeps the energy stored in the original form of mechanical energy the same as the moving vehicle. The flywheel needs to be coupled to the driveshaft of the vehicle in a manner which allows it to vary its speed independently of the moving vehicle in order to vary its energy content. In other words a continuously variable transmission (CVT) is needed. The common mechanical variators used in automotive applications, namely the rolling traction drives and the belt drives, have the disadvantage that their speed ratio range defined as the maximum to minimum speed ratio is generally not sufficient for flywheel energy storage system (FESS). One of the ways to improve the ratio range is by using a dual mode transmission, where the ratio coverage of the variator is exploited twice. This paper presents the fundamental kinematics of such a transmission including its variants. The equations of speed ratio, power flow and efficiency are derived for a variator only transmission and a power split CVT (PSCVT) used in dual mode and the results compared.
Dhand, AdityaPullen, Keith
A Study on Dynamic Torque Cancellation in a Range Extender Unit2016-01-12314/5/2016
A range extended electric vehicle (REEV) has the benefit of zero pipeline emission for most of the daily commute driving using the full electric mode while maintaining the capability for a long-range trip without the requirement of stop-and-charge. This capability is provided by the on-board auxiliary power unit (APU) which is used to maintain the battery state of charge at a minimum limit. Due to the limited APU package size, a small capacity engine with low-cylindercount is normally used which inherently exposes more severe torque pulsation, that arises from a low firing frequency. By using vector control, it is feasible to vary the generator in-cycle torque to counteract the engine torque oscillation dynamically. This allows for a smoother operation of the APU with the possibility of reducing the size of the engine flywheel. In this paper, a series of motor/generator control torque patterns were applied with the aim of cancelling the engine in-cycle torque pulses. The correlation between the electric machine torque profile and the engine in-cycle speed variation was investigated. As more aggressive use of the electric machine was made to achieve better system operation characteristic, the electric losses become more significant compared to constant torque strategy, as does the thermal impact. The results showed that within the target APU specification, the optimum speed fluctuation reduction of 21.9% could be achieved, while the M/G’s electric loss percentage rose from 3.5 to 4.7% at 4500rpm. An upgrade for cooling circuit specification was not considered necessary since the electric loss only increased by 2.5%. The Pareto frontier was also plotted for total electric loss against peak-to-peak engine speed variation.
Liu, DianRodrigues, LeonBrace, ChrisAkehurst, SamKirkpatrick, GaryAsh, Lloyd
The technologies NASA develops don’t just blast off into space. They also improve our lives here on Earth. Life-saving search-and-rescue tools, implantable medical devices, advances in commercial aircraft safety, increased accuracy in weather forecasting, and the miniature cameras in our cellphones are just some of the examples of NASA-developed technology used in products today.
Powertrain Architecture affects Driving Habits2014-01-286910/13/2014
The impact of the number of cylinders on two downsized gasoline engines on driving habits in the same passenger-vehicle type was investigated. This was carried out with two similar vehicles, equipped with an in-line three cylinder (i3) and an in-line four cylinder (i4) engine, both having same power, torque and transient-response behaviour. Both engine types were mated to six-speed manual transmissions with same gear-ratios and dual-mass flywheel characteristics. The study was performed by letting a statistically significant number of subjects driving the same route and both vehicles consecutively. The relevant data during driving were recorded simultaneously from either vehicle integrated sensors (CAN), and secondary transducers. We found that the in-line three cylinder was operated at higher engine speeds even though it was operated at similar acceleration- and load levels like the in-line four cylinder power-train, whereat the off-set of the engine speed shows no correlation with the difference in firing frequency between both engine types. Furthermore, it was revealed that the i3-engine faced gear-up-shift events at higher engine speeds than the i4-engine. Interestingly, the up-shift speeds in the individual gears show good correlation with the individual interior noise level characteristics. Based on the findings, potential countermeasures to enforce drivers of in-line three cylinders to drive at lower engine speeds can be made to ensure that the fuel-economy benefit of i3-engines is accessible even under real-world driving conditions.
Stoffels, HaraldHohenboeken, Kay
Fully Integrated IVT-Regenerative Braking2014-01-17274/1/2014
It is very important to note that most present-day CVT's drive with a friction element. Unlike gears that can be produced with any size necessary for the torque load they must transfer, CVT's are limited in torque capacity and are only marginally suitable for small vehicle applications. A system is described using two variable-inertia flywheels to not only supply the heavy torque requirements during acceleration of a vehicle but also operate in reverse capturing the otherwise wasted decelerating torque (I.E. braking torque). This system (called Kinetic Energy Power Transmission System or KEPTS) provides all of the documented benefits of the use of an IVT for motor vehicle acceleration and also incorporates regenerative braking. The significance of the system is that besides providing a complete KERS (kinetic energy recovery and storage) system, all accelerating and braking torque is provided by the two variable-inertia flywheels, thus allowing the main motive engine (ICE, electric traction motor, gas turbine, etc.) to operate at a fixed angular velocity (rpm) isolated from large torque variances, and the CVT elements can be minimized in size (I.E. low-torque). Mechanical (flywheel) kinetic energy storage is a formidable contender for regenerative braking systems and this is particularly the case for ICE (internal combustion engines) where few alternatives exist. Regenerative braking should be aggressively pursued for those vehicles with a rapid driving cycle (frequent start-stop cycles). The competing technology for all-electric vehicles is ultra-capacitors. When flywheel technology is implemented with an efficient, high-torque infinitely-variable transmission (IVT) a high percentage of the vehicle kinetic energy normally lost to friction braking systems can be returned to the vehicle during a brake-stop-launch cycle. Overall fuel use is then primarily determined by rolling resistance and air drag.
Gramling, James
Flywheel with tuned damping2014-01-16854/1/2014
The study of dynamical performance of new Flywheel for any type of engine is presented. Design and structure of proposed Flywheel is based on George Nerubenko US Patent 7,464,800 having the control system with instantaneous frequency tuner and variable damping device adjusted for all operational frequencies in running engine. The patented scheme would be applied for a design of Flywheels successfully replacing the conventional and dual mass flywheels. A description, structural details and mathematical model of considered Flywheel are presented. The model based on the system of differential equations describing the rotation and vibration of mechanical components combined to Coulomb dry friction equations reflecting the contacts in variable damping device has been used for the analysis of the dynamic behavior of engine crankshaft system having proposed Flywheel. The analysis is presented for semi-controlled version of Tuned Flywheel equipped with variable damping device. The presented solutions are allowing be concentrated on a reduction of the variations of instantaneous value of rotational speed (angular velocity) forcing the elimination of a coefficient of fluctuation of rotational speed. Tests have been conducted for a comparison of the dynamic performance of presented Flywheel to dynamic data of conventional and dual mass flywheels. Test results of prototype of Tuned semi controlled Flywheel equipped with variable damping device show the reduction of a coefficient of fluctuation of rotational speed to 0.004 which is lower than required bottom level.
Nerubenko, GeorgeNerubenko, Cyril
This SAE Recommended Practice defines flywheel housing flange configurations for applications requiring "O" ring sealing of the flange pilot bore. Table 1 and Figure 1 show dimensions that are different from those in SAE J617. All other dimensions and tolerances of SAE J617 apply.
SAE IC Powertrain Steering Committee
Analysis of the Friction Losses in an Internal Combustion Engine2012-36-030310/2/2012
This work presents the results of the study of the forces involved in the rubbing friction between the moving parts of the Otto cycle internal combustion engine. In order to study the friction force, a Honda GX 35 engine was modified and a load cell was attached to its chassis. The friction forces among the internal parts of the engine were transferred to the engine chassis, and, by means of a support, to the load cell. Those forces were measured in several situations of the engine, making possible to identify the amount of friction related to each component. The total measured friction power was equal to 112W, representing about 10% of the developed power of the engine. The results obtained by the tests showed the contribution of each individual part of the engine on the friction losses. By the results, it was possible to propose modifications to reduce the total internal friction of the engine, in order to increase its efficiency. After the measurements of the friction force related to different components of the engine, new measurements were carried out in order to analyze the influence of the geometry of the pistons on the friction. During the tests, they were employed pistons with different geometries in relation to the original one. When a modified piston was employed, a reduction of up to 24% could be obtained on the values of friction when compared to those ones produced by original crankshaft - rod - piston assembly. Most of the friction energy is dissipated as heat through the coolant and lubricant. This heat is removed from the system by the water and oil radiators, so the friction losses also have great influence in the cooling system design.
Da Silveira, Marilia AmaralGertz, Luiz CarlosCervieri, AndreRodrigues, Antonio Flavio AiresSenger, Marcio
Identification and Correction of the Error Induced by the Sampling Method Used to Monitor Cylinder Pressure of Reciprocating Internal Combustion Engines2012-01-11554/16/2012
Cylinder pressure measurements are common practice for internal combustion reciprocating engines during field or lab applications for the purpose of combustion analysis, condition monitoring etc. The most accurate method is to measure cylinder pressure using a crank angle encoder as a trigger source to guarantee cylinder pressure measurement at predefined crank angle events. This solution, even though favorable, presents a number of practical difficulties for field applications and increased cost, for this reason its use is practically restricted to lab applications. Therefore a commonly used approach for ad hoc measurements is to digitize samples at fixed time intervals and then convert time into crank angle assuming a constant rotational speed. But if engine rotational speed is not constant within the engine cycle this may result to incorrect cylinder pressure CA referencing. To identify the error introduced from improper cylinder pressure CA phasing, and to propose methods to minimize the negative impact on the measured cylinder pressure traces, an experimental setup has been developed based on a single cylinder prototype DI diesel engine. Measurements were performed using the two aforementioned technical solutions with simultaneous measurement of the engine instantaneous rotational speed. The direct comparison of the two sets of measured cylinder pressure traces reveals the introduced indexing error. Following this, an attempt is made to propose a correction methodology based on the estimation of the engine instantaneous rotational speed. For its estimation three different methods are proposed and evaluated. The first method makes use of a low resolution instantaneous speed signal, provided by a sensor reading marks on the engine flywheel, the second makes use of the BDC and TDC events and the third is based on the comparison of the duration of the compression and expansion phases. As revealed from the analysis all three methods results to a reduction of the error induced in the estimation of Indicated Work by a magnitude of 10 times i.e. from up to 7% to less than 1%.
Antonopoulos, AntonisHountalas, Dimitrios
Performance Analysis of the Impulse Shift CVT2004-40-00238/23/2004
Due to rotating inertias within the engine and transmission, the response of a vehicle during large engine speed shifts may appear reluctant or even counteractive. To overcome this behaviour, a CVT drivetrain was augmented with a powersplitting planetary gear stage and steel flywheel in the so-called Zero Inertia (ZI) powertrain [1]. This transmission concept managed to combine two contradictive goals: the driveability in terms of the pedal-to-wheel response is greatly improved; and a large leap towards optimal fuel economy can be made. These goals were achieved by cruising the vehicle at extremely low engine speeds, enabled by the large ratiocoverage of the CVT. The flywheel acts as a 'peakshaver' during engine speed transients: it delivers power during (semi-) pedal kickdown and absorbs the engine's kinetic energy at pedal back-out. The current paper presents an improved concept with respect to the Zero Inertia drivetrain, which enables a reduced flywheel size while enhancing the pedal-towheel response even further. This concept is designated the Impulse Shift CVT (IS-CVT). The IS-CVT incorporates a slightly modified drive clutch and uses it to interrupt the power flow through the CVT during kickdown accelerations. Disengaging the drive clutch directs the entire engine power flow through the parallel (flywheel and planetary gear) branch, resulting in an immediate flywheel assist while the engine speeds up rapidly. When the engine has reached its desired speed, the drive clutch is re-engaged and the power flow through the CVT is reinstated. The presented IS-CVT concept enables much faster speed transients, independent of the CVT shift rate, resulting in a more effective use of the flywheel energy. Hence the flywheel can be reduced, and the ZI effect can be exploited to the fullest. Furthermore, the demands on the variator actuators can be lower.
Vroemen, BasSerrarens, AlexPesgens, MichielVan Druten, Roell
P.A.R.I.S.: Pendulum acyclism reducer integrated system2000-05-03206/12/2000
Evolution of automotive diesel engines has led to the production of smaller and smaller engines with increasingly higher torque. The reduction in external dimensions means smaller flywheels, and the increase of torque rates, higher cyclic irregularities that today''s flywheels even with dual mass techniques are no longer able to cope with. Because of this, "damper" type absorber devices which control torque vibrations due to cyclic irregularities are no longer efficient to decrease rotating vibrations to an acceptable level. The best solution to cope with these problems is a tuned rotating pendulum: P.A.R.I.S. (Pendulum Acyclism Reducer Integrated System). This vibration absorber system can be easily integrated into a standard engine flywheel. P.A.R.I.S. systems show a very high efficiency level. Normally, in order to decrease the 2nd harmonic level (mainly responsible for cyclic irregularities in 4 strokes 4 cylinders engines) to 60%, a standard flywheel would have to have around 15 times its actual mass. The mean torque level is not affected by P.A.R.I.S., only the instantaneous torque in counterbalanced by the pendulum. In addition, the P.A.R.I.S. system device has the great advantage of being independent of engine speed. It is efficacious throughout the whole range of speed, as compared to damper vibration absorbers, which are tuned for a specific frequency. On the other hand, P.A.R.I.S. is not adapted for the whole harmonic range generated by the engine, but only for those harmonics it has been tuned for. Another positive aspect of this solution is that it is a full mechanical system, needing no electronic controls, which consumes hardly any energy and these due only to small friction losses. Application examples targeted by this patented system are: torque regulation, due to reduction of cyclic irregularities in order to achieve smaller vibration levels, idle speed decrease for consumption and pollutant reductions, in camshaft applications - increase of the maximum rotating speed.
Vidal, FabriceDrecq, DanielLouradour, Guy
This SAE Standard was developed to provide a method for indicating the direction of engine rotation and numbering of engine cylinders. The document is intended for use in designing new engines to eliminate the differences which presently exist in industry.
Engine Power Test Code Committee
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