Forklift Hydraulic System Design

Transcription

1 Applied Mechanics and Materials Online: 0-0- ISSN: , Vols. 0-06, pp doi:0.408/ 0 Trans Tech Publications, Switzerland Forklift Hydraulic System Design Yu Chun, a, Wang Youmin,b,Zhao Chun,c School of Mechanical and Automotive Engineering. Anhui Polytechnic University Wuhu city, 4000,China a yu_chun@6.com, b wymtlf@6.com, c zhaochun5@6.com Keywords: Forklift ; Hydraulic system design; Check Abstract. In order to improve design performance, shorten development cycles, reduce production cost, designed the forklift hydraulic system. By the analysis of the forklift tilting and lifting process, the forklift hydraulic system schematic is made. Based on the schematic, designed and calculated the size and operating parameter of hydraulic cylinder, the pump operating parameter, hydraulic valve operational parameter, hydraulic oil tank effective volume, pipe size, selected the appropriate hydraulic components, and checked the system pressure loss and temperature rise. The results show that the hydraulic system meets the requirements. Introduction Forklift truck is a self-traveling handling equipment. It is used widely in plant, port, warehouse and stations and other places at present. Hydraulic system is an important part of forklift. Forklift mainly through hydraulic control to achieve the steering, goods fork lift, mast tilted and other functions,which with the main features of a high voltage, energy saving, integration, low noise, safe and reliable, and good control performance, no leakage, widely used mechanical and electrical integration, etc. Domestic forklift hydraulic systems usually use fixed displacement pump and throttling control type hydraulic system which composed of switch type multiple valve. The characteristics of this system are that the simple oil-way, mature component technology, good reliability. But the shortcoming is obvious, namely bad fine-tuning characteristics, large energy consumption, steering hydraulic system is general composed by fixed displacement pump, single firm the purge valve and full hydraulic steering gear or priority valve and load-sensing hydraulic steering gear. The latter combination which used load-sensing technology has certain energy-saving effect is the development direction of small and medium-sized forklift steering hydraulic system. With the expansion of the market and the needs of society, forklift hydraulic control technology will gradually leads toward low energy consumption, high efficiency, environmental protection and electromechanical integration direction. A hydraulic system design Forklift working procedure parses. Lean process: Lean working process, just by the piston rod movement of tilt cylinder to drive the rotation of the kinematic door frame.the movement of kinematic door frame to drive the movement of fork. The velocity of the hydraulic cylinder is relatively slow in this process, with an average speed is 0. m / s, the external load is about 000N. As the quality change of the goods loaded, the speed of the hydraulic cylinder is even less demanding. Lifting process: The average speed is about 0.5 m / s in this process, the stability of speed is demanded, external load is approximately 0000N. In lifting process, drive fork movement by elongating the lifting cylinder piston rod to, and to achieve the function of lifting the goods. The development of hydraulic schematic diagram: () Determine the supply mode. Taking into account the larger load, slower speed when forklift hydraulic cylinder work. Consideration from the saving energy, reducing heat, the pump source system should use fixed displacement pump to pump All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-09/05/6,0:9:57)

2 Applied Mechanics and Materials Vols oil. Now adopt the one-way quantitative vane pump. () Speed for access mode choice. The system used the manual valves of speed for access loop, which is characterized by simple structure, adjust the schedule more convenient, easier to install the valve. () The choice of speed mode. Hydraulic cylinders all used the inlet throttle speed, this speed control circuit with the feature of high efficiency, small heat and good rigidity of speed. (4)Used double-acting multi-stage hydraulic cylinder, to avoid and reduce engine failure rate caused by road bumps in empty return trip, reduced the space occupied by the hydraulic cylinder to improve the truck's load at the same time. Finally, assembled the selected hydraulic components together, the results of hydraulic schematic diagram show in Figure. Figure Forklift hydraulic system diagram - relief valve; - speed control throttle;,4 three-position six-way manual valve; 5,6,7,8 - throttle The calculation of hydraulic system and the selection of hydraulic element. () The relevant parameters of lifting hydraulic cylinder rand tilt cylinder are shown in Table and Table respectively. Table The parameters of the hydraulic Working pressure (Mpa) Back pressure (Mpa) ID Piston rod diameter Cylinder wall thickness Travel Overall length of the cylinder Lift cylinder Tilt cylinder Table The thickness of the cylinder cover and cylinder Hole thick-ness Thickness without Cylinder elongation Cylinder when the flow holes flow (L/min) rate reduced(l/min) Lift cylinder Tilt cylinder () Pump working pressure was determined by the formula (): p p p + Σ p () In the equation (): p p -pump maximum working pressure; p - maximum working pressure of actuator; Σ p-pressure loss in the intake pipe road. Then p p p +Σ p MPa

3 750 Sensors, Measurement and Intelligent Materials () Determine the pump flow ( Σq) max q p K L () In the equation (): qp pump maximum flow; KL-system leakage coefficient, generally taken to KL.~.; ( Σq) max the maximum of that the sum flow of action at the same time of the implementation of the components required. Then q ( Σq) max.l/ min p K L, take q p 8L/min (4) Selected the specifications of hydraulic pump. According to pp and qp, check manual, selected the quantitative vane pump YB-E80, the nominal displacement is 80ml / r, rated pressure is 6MPa, the minimum speed is 600r/min. (5) The selection of hydraulic valves, are show in Table. Table Hydraulic valve schedule No. The name of the valve Code Parameters Relief valve BUCG-06-0 Set pressure6(mpa) Throttle valve MG(K)-0 Maximum flow 00(L/min) Three-position six-way manual valve DMG-0 Maximum flow 80(L/min) 4 Three position six-way manual valve DMG-0 Maximum flow 80(L/min) 5, 6 Speed throttle valve DV-0 Maximum flow 009(L/min) 7, 8 Speed throttle valve DV-0 Maximum flow 00(L/min) (6) Determination of hydraulic oil tank effective volume In the mid-high pressure or high pressure power system(p>6.mpa): V(6~) q p () In the equation (): V-the storage capacity of hydraulic oil tank; q p -pump rated flow. Taking V L (7) Determined the size of pipeline. Inner diameter of tubing is generally reference to the optional hydraulic component interface dimensions, it can also be calculated by the flow rate of pipe allows. Lifting oil flow of the system is 9.47L/min, took the flow of hydraulic tubing allowed is v 0m / s, the inner diameter d 8.6 mm. Taking all factors, now take 0mm as inner diameter of tubing. System Check Check the performance of hydraulic system. Because the fast-forward, the oil flow is the maximum in the pipeline, so just check the pressure losses when the fast-forward. The calculation of Pipe Reynolds number, judged the type of oil flow. The speed of hydraulic oil in pipe: 4qmax v πd Brought into the data and got that: (4) v 4.96m/ s π Similarly, the return oil flow v.96 m/s Intended for use L-HL- common hydraulic oil, from product manuals to look up the movement 6 of oil viscosityγ 5. 0 m / s

4 Applied Mechanics and Materials Vols The Reynolds number of into the circuit is R vd R e 88.8> 00 (5) 6 γ 5. 0 Reynolds number of back to the oil: R e vd < 00 6 γ 5. 0 Therefore, the type of oil was the laminar flow and turbulence. Calculation of total pressure loss along the way l ρv p λ (6) λ d 75 λ Took R e, both into and return pipe, were m, oil densityρ 900kg/ m. The pressure loss along the way of into the oil λ λ Pa 0. 09MPa λ Pa 0. 07MPa and pressure loss along the way of return to oil λ were: The integrated pressure loss calculate. Inside the integrated, the line is shorter, can be regarded as partial loss, hard to calculate. Set the into and the return oil pressure loss in the integrated were same according to experience, its estimated value was 0. MPa Local pressure loss of valves each component. The component number of the into circuit when fast forward is,, 5, 6. r MPa When oil back Into oil Σ P r 0. 76MPa, the total pressure loss 0.89MPa λ + r Back to oil 0.88MPa λ + r This value together with the work of the hydraulic cylinder pressure (the pressure determined by the external load) and the pressure which the relay system required to increase (Whichever is.mpa), that can be as the reference data of less than estimated adjustment pressure of relief valve.

5 75 Sensors, Measurement and Intelligent Materials P + P MPa System selected the vane pump rated pressure is 6MPa, the set pressure of relief valve is MPa. Because.08., it can be used as reference data. Heat and temperature rise of hydraulic system check. The working hours of Forklift mainly is lifting conditions, to simplify the calculation, the main consideration is the heat when lifting, so checking system temperature by lift conditions. The input power of pump: When lifting, the pressure loss is P0. 04MPa, Q P m / s P p pq η p p W (7) η The total efficiency of hydraulic pumps (look-up table 4 get) P P p 87. W 0.9 Table 4 A variety of pump efficiency under the nominal pressure Pump name Gear Pump Screw Vane pump Radial piston pump Axial Piston Pump Overall efficiency 0.65~ ~ ~ ~ ~0.9 ηp Effective power When lifting, the load of hydraulic cylinder F 0000N, lifting velocity V 0.05m / s, Output power P 0 is P FV W 0 System heating power: P i h P P W Thermal Area The capacity of fuel tank: V 768L m Approximate heat area of the tank 6.5 ν 5.45m Oil temperature rise T Assumes using air-cooled, taking the fuel tank heat coefficient is C T W /( m C) Ph 87. T. C ΣC A 5.45 T (8)

6 Applied Mechanics and Materials Vols In the equation (8): P h -system heating power Set the summer temperature is 0 C, the oil temperature is: 0 C+. C 4. C Take [T] 55 C for general machine tools, T <[T], so the heat balance to meet the requirements. Conclusion Through the analysis of forklift hydraulic system work process and fit the forklift Hydraulic System Diagram. On this basis, to design and calculation the hydraulic cylinder size and the operating parameters, the pump operating parameters, hydraulic valve operating parameters, the effective volume of the hydraulic oil tank, the pipe size. Selected the appropriate hydraulic components. Finally, to check the system pressure loss and temperature, the results showed that meet the requirements. References [] You-min Wang. Hydraulic and atmospheric pressure transmission and control [M]. Wuhan: Huazhong University Press, 009. [] Guosen Du. Hydraulic components samples [M]. Beijing: China Machine Press, [] Peiyuan Yang, Fuyuan Zhu. Hydraulic system design simple manual [M]. Beijing: China Machine Press, [4] Qing-hua He, Peng Hao, Daqing Zhang. Modeling and parameter estimation for hydraulic system of excavator s arm[j]. Cent.SouthUniv. Technol.(008)5:8-86. [5] Yuanchang Lu. Hydraulic system modeling and analysis [M]. Shanghai: Shanghai Jiaotong University Press, 989,. [6] Yaming Zheng. CPCD80A forklift hydraulic system of high oil temperature control [J]. Beijing: forklift technology 009,0. [7] Stem.Jeffrey. Southgate Douglas and Strasma. John. Improving garbage collection in Latin America s slums: some lessons from Machala Ecuador. Resource [J],Conservation and Recycling.997,7. [8] Eugenio de0iveira Simonetto, Denis Borenstein. A decision support system forthe operational planning of solid waste collection [J], Waste Management,006.06

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