Wyniki wyszukiwania - BazTech

1

Quarter car model to evaluate behaviour under road and body excitation

Niculescu A. I., Jankowski A., Kowalski M., Sireteanu T.

Journal of KONES

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2017

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Vol. 24, No. 1

265--273

EN

The paper presents a quarter car model two degrees of freedom (wheel and body), with vertical guiding system, the model being equipped with suspension stroke limiters and with excitation by wheel and/ or by body. The model reproduces elastic and damping characteristics of wheel and of rebound and compression stopper bumpers, the spring elastic characteristic and the shock absorber damping characteristic on rebound and compression, function piston speed. The road profile is generated with simple or summation of harmonic functions, or by reproducing real roads. The forces acting on full vehicle body e.g. aerodynamic and inertial forces are reproduced in the proposed quarter model by vertical forces reduced to the analysed quarter part. Thus, the model can be used for evaluation the vertical and horizontal stability at acceleration, deceleration, pitch and roll, at aerial forces, the body ground clearance and the comfort. The model can evaluate the influence of the damping and elastic characteristics of suspension and wheel, of the static position, of the vehicle load state, of the road profile and of the external forces, to the vehicle behaviour

2

Advantages conferred by shock absorbers with cylindrical actuator application to landing gear

Niculescu A. I., Jankowski A., Kowalski M., Sireteanu T.

Journal of KONES

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2016

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Vol. 23, No. 1

255--262

EN

Shock absorber with cylindrical actuator is a new concept of integrated damper with floating device, in international patent application PCT/EP2016/061515, with wide application in road, rail and aerial vehicles. Comparative to the known solution with rubber sleeves or bellows, the new one is capable to work at more increased pressure being more compact and due to metallic cylinder is more reliable. The other important advantage consists of it applicability at any kind of shock absorber without any special preparation, the solution consisting of replacing the dust shield with a pneumatic cylinder sealed against rod with a gasket and sliding closed in the lower part by sealing element/s fitted in trough/troughs practiced in an annular body fastened against the outer cylinder. For a better behaviour the patent application contains and solutions with double sliding sealing working at high pressure and thus assuring enough floating forces to sustain the vehicle without standard metallic spring so it can be utilized successfully in aerial vehicles landing gear. By using displacement and pressure transducers and equipment of control and command, it becomes an active suspension. The paper presents the double sliding sealing solution and demonstrates, by simulation the advantages confer by this new solution of shock absorber with cylindrical actuator in landing gear. This purpose was realized a virtual suspension model on which simulated hard landing for vehicle load and unload states, for different pneumatic spring preloaded forces.

3

Novel damper for passive security increasing

Niculescu A. I., Jankowski A.

Journal of KONES

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2010

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Vol. 17, No. 1

299-308

EN

Horizontal crash at road and rail vehicles generates human and material injuries, many of them with important negative effects. Damper in bumper a known solution for vehicles protection at crash is realized with different damping devices, from passive elements to actuators. Usually the devices are tunedfor 5 km/h crash speed. After collision the passive solutions destroy and must be removed with other new devices. The solutions using standard shock absorbers and actuators are improper the first dissipating insufficient energy and actuators being more expensive and having a long reaction time so the damping coefficient changing is realized in too low steps. VZN damper concept granted with European Patent EP l 190 184 and Romanian Patent RO l 18546, characterized by progressive damping coefficients with the stroke is a great opportunity to realize simple and cheap protection at crash, due to its capacity to realize constant damping force without mechanisms and electronics. li is necessary only to tune accordingly VZN damping characteristic to this desiderate. VZN concept consist of u piston rod attached to a piston without valves moving inside inner cylinder close at both ends and filled at rebound and compression by specific fllling valves placed in upper /bottom lids or on the ends of the inner cylinder. The damping effect is realized by valves or in cheap solution by metering orifices (holes/slots) placed sideways inner cylinder in convenient position. Due to this structure VZN tuning for constant damping force at different piston speed can be realize both with identical metering holes/slots placed at optimal distances, or placing metering holes/slots of different areas at eąual distances. The numbers of metering holes/slots are enough such the steps speed evolution be practical continuous and thus the damping force be practical constant. The VZN behaviour is increased by new components e.g. levelling pistons, double guiding elements and balancing solutions. Paper presents the theory used to dimension VZN damper placing metering orifices at eąual distances, a practical device with levelling piston and simulation comparative to standard one. The standard damper dissipates 30-40% lower energy comparative to VZN one. This means in the same situation in which VZN damper reduces constant speed from 30, respectively 20 [km/h] to zero, the standard dampers reduces speed up to 14, respectively 11 [km/h], then collapsing the vehicle.

4

On „VZN" damper behaviour at crash

Niculescu A. I., Jankowski A., Sireteanu T.

Journal of KONES

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2009

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Vol. 16, No. 2

369-374

EN

On landing operation, a brutal contact with the dech or ground, can damage the plane or chopper and hurt the pilot, the crew or the passengers. The paper presents the advantages confer by suspensions using VZN dampers, in this situation. The Romanian self adjustable damper (shock-absorber) concept- VZN-granted with European Patent EU 1190184 and Romanian Patent 118546 assures damping coefficients increasingly by stroke from lower value up to the very high values, giving thus possibility to dissipate a huge energy at all speed regimes high, medium or low. With a convenient damping valve placement and/or dimension, the VZN concept confers possibilities to assure constant decelerationforces, at the human body limit resistance, this solution dissipating the maximal energy ąuantity. The paper indicates solutions for VZN tuning in order to be used to realize constant deceleration at crash and developed one of them for a practical device realizes. The samples where developed so to be realized with components used in actual automotive shock absorber manufacturing, so prototypes being easy to realize. Despite the simulations was realized considering standard damper dissipating energy function piston speed, not sąuare piston speed, the standard damper dissipated 48.5% lower energy comparative to VZN one. This means in the same situation in which VZN damper reduces constant speed from 20 [km/h] to zero, the standard dampers reduces speed up to 11.5[km/h], then collapsing the aerial vehicle.

5

A solution for crash and high ground unevenness effect reducing

Niculescu A. I., Alexandru C., Jankowski A.

Journal of KONES

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2008

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Vol. 15, No. 3

389-395

EN

On landing operation, a brutal contact with the deck or ground, or high ground unevenness can damage the plane or chopper and hurt the pilot, the crew or the passengers. The paper presents the advantages confer by suspensions using VZN dampers, in this situation. The Romanian self adjustable damper (shock-absorber) concept-VZN-granted with European Patent EU 1190184 and Romanian Patent 118546 assures damping coefficients increasingly by stroke from lower value up to the very high values, giving thus possibility to dissipate a huge energy at all speed regimes high, medium or low. With a convenient damping valve placement and dimension, the VZN concept confers possibilities to assure constant deceleration forces, at the human body limit resistance, this solution dissipating the maximal energy quantity. The paper evaluates by simulation, the behaviour at vertical crash of aerial vehicles equipped with suspension using VZN and standard dampers. The results given by VZN concept is 200% better than the standard dampers, this new solution giving high possibilities to reduces the risk at landing, a better passengers and body protection, without increased costs. The VZN principle, and damping coefficients, comparative with standard and monroe sensa trac, the kinematic model, speed - time and acceleration evolution for VZN and standard dampers, detail for acceleration - time evolution at VZN and standard dampers acceleration - time evolution for VZN and standard dampers are presented in the paper.

6

Design solutions and active safety increasing for "VZN" shock absorbers

Niculescu A. I.

Journal of KONES

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2007

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Vol. 14, No. 4

295-306

EN

The paper presents the principle, some design solutions and last theoretical and by simulation results, for the suspension realized with the self-adjustable shock absorber, called shortly VZN, relative to the standard one. The self-adjustable shock absorber VZN, an intelligent shock absorber, realized without electronics or mechanisms, grant with European Patent EP1190184B and Romanian Patent 118546, is much better than standard ones because confers possibilities of stepwise adjustment of damping force as function as the instantaneous piston position. That means lower damping coefficients at the stroke beginning, for easier medium position arriving for a well adherence, damping coefficients for well correspondence between comfort and adherence, in the medium area, high damping coefficients both adjacent parts at the medium area for better adherence and well axle movement brake, and very high damping coefficients at the ends, for better body and axles protection. This concept is realized with planar or circular valves, a new patent request presenting specific solution. The cheaper and compact solution uses metering holes like damping valves, some of these being presented in the paper. The theory shows its great damping coefficient evolution with the stroke, give progressive anti-gyration effect and regressive redressing gyration effect along vehicle body transversal and longitudinal axes, increasing pitch and roll stability. Simulation tests denote high performances for VZN shock absorbers, relative to standard one, its great adaptation capacity relative to load, road condition, and efficiency, better body stability-skyhook behaviour, better protection at the stroke ends, lower RMS body acceleration, improving pitch and roll stability at and so active safety increasing. So the automotive self-adjustable shock absorber VZN, confers high performances, nearly semi-active suspensions at low costs, nearly standard shock absorbers being an important option for the future.