Scientific Journal of Silesian University of Technology. Series Transport Zeszyty Naukowe Politechniki Śląskiej. Seria Transport

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1 Scientific Journal of Silesian University of Technology. Series Transport Zeszyty Nauowe Politechnii Śląsiej. Seria Transport Volue p-issn: e-issn: DOI: Journal hoepage: Article citation inforation: Jírová, R., Svoboda, R., Peší, L. Seat suspension syste of the electric golf cart. Scientific Journal of Silesian University of Technology. Series Transport. 08, 99, ISSN: DOI: Rada JÍROVÁ, Roan SVOBODA, Luboír PEŠÍK 3 SEAT SUSPENSION SYSTEM OF THE ELECTRIC GOLF CART Suary. The paper deals with reducing vibrations transitted fro electric golf cart wheels to the seat and the seated person. These vibrations appear while driving a golf cart on uneven terrain of a golf course. This proble can be solved by using the elastic and daping lin between the cart frae and seat, which is tightly connected to the electric power battery. A atheatical calculation is used to evaluate the designed solution in which the golf cart is defined as a syste of asses connected with elastic and daping lins. The result of the designed solution s atheatical description provides a reference step response of the golf cart seat. Keywords: suspension syste; golf cart seat; iniization of vibration. INTRODUCTION Suspension seats are used in a wide range of vehicles, especially for the purpose of protecting people s health when exposed to whole-body vibration during travel, and also increasing cofort. Driving on the uneven terrain of a golf course leads to the high-intensity vibration of wheels, which is transitted to the frae, the seat and the seated person. As conventional battery-powered electric golf carts do not have suspension seats, the elastic and Faculty of Mechanical Engineering, Technical University of Liberec, Czech Republic. Eail: rada.jirova@tul.cz. Bag Developent s. r. o., Mladá Boleslav, Czech Republic. Eail: roan.svoboda@afd.cz. 3 Faculty of Mechanical Engineering, Technical University of Liberec, Czech Republic. Eail: luboir.pesi@tul.cz.

2 90 R. Jírová, R. Svoboda, L. Peší daping lin between the chassis and frae is used to reduce transitted vibrations to the seat and the seated person. Such a lin only partially reduces the transission of vibrations, eaning that driving in a golf cart can still becoe uncofortable.. EFFECT OF VIBRATION ON COMFORT Evaluating the effect of vibration on the cofort of the seated person while driving a golf cart was ade in accordance with []. The result of this evaluation relates to the frequency-weighted root ean squared (RMS) acceleration of the easured acceleration as a function of tie during the golf cart drive; see the coparison with this acceleration value in the table in []. A coparison of the frequency-weighted RMS acceleration with the table in [] shows that the effect of vibration on cofort during golf cart driving is in interval between uncofortable and very uncofortable [3]. 3. REDUCTION OF TRANSMITTED VIBRATION Miniization of vibration, transitted fro golf cart wheels to the seat and the seated person, is based on the principle described in the patent application. Seat Daper Golf Cart Frae Battery Spring Guiding Mechanis Fig.. Principle of vibration isolation of the seat Transitted vibrations can be reduced by using the elastic and daping lin between the cart frae and seat, which is tightly connected to the electric power battery. As a result of this tightness, the seat increases the inertial effect of ass, which reduces seat vibration. The principle is shown in Fig..

3 b Seat suspension syste of the electric golf cart TRANSMITTED VIBRATION CALCULATION The syste shown in Fig. can be described in a siplified way by differential equations: () where is the ass of the frae, is the ass of the seat, battery and seated persons, is the daping coefficient of the chassis, is the daping coefficient between the seat with the battery and the frae, is the stiffness of the chassis, is the stiffness between the seat with the battery and the frae, is the deflection of the chassis, is the deflection of the frae, and is the deflection of the seat with the battery. The syste can be presented in a siplified atrix for by the following equation: (3) where is the vector of deflection, is the atrix of stiffness, is the atrix of daping, is the atrix of ass, is the vector of the force substituting deflection, is the angular frequency and is the iaginary unit. In the case of using an elastic and daping lin between the golf cart frae with a tightly connected battery and the seat, the differential equations are: (4) where is the ass of the seat and seated persons, is the daping coefficient between the seat and the frae, is the stiffness between the seat and the frae, and is the deflection of the seat. () (5) u( t), u( t) (x -u) (x -u) q, q, q q, q, q q q b b b (x -u) b (x -u) Fig. 3. Description of Eqs. -5 b q F( t) b b q b q q The results obtained by Eqs. -5 coprise the aplitude-frequency response, as shown in u( t), u( t) Fig. 4, and the reference step response of systes, as shown in Fig. 5. x, x, x (x-u)

4 9 R. Jírová, R. Svoboda, L. Peší Fig. 4. Aplitude-frequency response Fig. 5. Step response of systes: acceleration-tie graph Driving a golf cart on uneven terrain of a golf course leads to non-periodic and nonharonic vibration. In a siplified way, this vibration can be represented by separate step functions. The deflection in differential Eqs. -5 can be substituted by a reference step signal. The aplitude-frequency response, as shown in Fig. 4, is the decisive reference step response of a syste when evaluating the effect fro increasing seat inertia.

5 u( t), u( t) (x -u) (x -u) q, q, q q, q, q q q q F( t) Seat suspension syste of the electric golf cart TRANSMITTED VIBRATION EVALUATION b b b b The syste of an electric golf cart without a suspension b seat q can be described b q in a b siplified way by (x the -u) following differential b (x -u) equation: (6) q where is the deflection of the frae with a seat. u( t), u( t) x, x, x (x-u) b b (x-u) Fig. 6. Description of Eq. 6 The result obtained fro differential Eqs. -6 is the reference step response of systes. The acceleration-tie graph for the suspension seat and the seat tightly connected to the golf cart frae is shown in Fig. 7. Fig. 7. Step response of systes: acceleration-tie graph

6 94 R. Jírová, R. Svoboda, L. Peší 6. CONCLUSION The paper deals with the current issue of the vibration isolation of golf cart seats. The solution uses the inventive concept of increasing the inertia of the tightly connected ass in relation to seat. This significantly reduces the vibration transitted fro the golf cart wheels to the driver and passenger. References. ČSN ISO 63-. Vibrace a rázy - Hodnocení expozice člověa celový vibrací - Část : Všeobecné požadavy. Prague: Česý noralizační institut, 999. [In Czech: Vibration and shoc - Assessent of huan exposure to total vibration - Part : General requireents. Prague: Czech Standards Institute, 999.]. Dresig Hans, Franz Holyweißig Maschinendynai. [In Geran: Machine Dynaics]. Berlin: SpringerVerlag. 3. Sapietova A., V. Deys. 06. Use od Msc. Adas software product in odeling vibration sources. Kouniacie a (0): Received ; accepted in revised for Scientific Journal of Silesian University of Technology. Series Transport is licensed under a Creative Coons Attribution 4.0 International License