Research of the Bus Secondary Hydraulic Transmission System under Variable Pressure Rail

Transcription

1 Research of the Bus Secondary Hydraulic Transmission System under Variable Pressure Rail Zan Faye 1, Wan Yon 1 Department of Enineerin Mechanical, Shandon University, Jinan, China Shandon Jiaoton University, Jinan 50357, China ABSTRACT International Journal of Research in Mechanical Enineerin Volume, Issue 6, November-December, 014, pp Online: Print: , DOA : IASTER 014, Hydrostatic transmission with secondary reulation can reenerate inertial and ravitational enery of load. Based on deeply analyzin the workin principles and enery-savin theory of the secondary reulatin transmission system under variable pressure rail, reeneratin the transmission system s inertial enery by controllin power was put forward. Considerin lare chanes of the parameters of the transmission system and its non-linearity, a fuzzy-neural network control was adopted, and the mathematical model of the system was established, then the simulations of the performance of the transmission system has been conducted. The conclusion was made that the inertial enery can be reclaimed and reused, and the self adaptive ability and controllin performance of the secondary hydraulic transmission system is improved. Keywords: Secondary Hydraulic Transmission, Fuzzy-Neural Network Control, Constant-Power Control, Performance Research. 1. INTRODUCTION Secondary reulatin static-liquid transmission technique is reulatin for the secondary element that inter-converts hydraulic enery and mechanical enery. By reulatin displacement of the secondary element, rotary speed or torque of load can be reulated. By chanin oil-flowin direction of the secondary element (passin zero point), the secondary element has workin states of both hydraulic motor and hydraulic pump [1]. When workin in the motor state, the secondary element outputs power to the load. When workin in the pump state, the secondary element recycles brakin enery of the system. When used for the transmission system of the locomotive machine which works in periodicity, in particular the bus that continually starts and stops, the secondary reulatin static-liquid transmission technique can reatly advance efficiency of the system, save enery and reduce environmental pollution.. ENERGY-SAVING MECHANISM of the TRANSMISSION SYSTEM The bus transmission structure showed in Fi. 1. The secondary reulatin transmission system consists of the enine(1), clutch(,5), ear-box(3), earin(4), accumulator(6), secondary element(7), rear bride(8). It drives the bus in the form of that mechanical enery of the enine and the secondary element 15

2 International Journal of Research in Mechanical Enineerin Volume-, Issue-6, November-December, 014, (O) (P) work toether to drive the bus []. It includes two power-drivin systems. The first system is that the power of the enine is transmitted to the drivin system by the clutch, which is the same as that of the bus. Another system is the hydraulic drivin system that transmits enery by the hydraulic pump, accumulator, secondary element and transmission shaft. These two systems can be used jointly or respectively. When climbin slope or acceleratin, the bus is driven by two drivin systems jointly with assistance of the hydraulic system. When runnin commonly, the bus is driven by the enine directly. When the bus is braked, the secondary element works in hydraulic pump state that recycles brakin enery of the bus and save it into the hydraulic accumulator in the form of hydraulic enery. In the process of start and acceleratin, the hydraulic enery in the hydraulic accumulator can drive the bus by the secondary element that works in hydraulic motor state. 3. STRUCTURE AND WORKING PRINCIPLE OF DOUBLE-ACTING VANE-TYPE SECONDARY ELEMENT The double-actin vane-type secondary element mainly consists of the rotor (4), stator (), vane (3), variable cylinder (10), shell (1) and distributin tray (not showed in the Fi. ) showed in Fi.. The variable cylinder (10) consists of the variable rod (6), variable piston (8) and body (9). The ball-shape head of the variable rod is connected with the roove of the variable piston. Another side of the variable rod is fixed at central line of lon radius arc of the stator. Another side of the variable rod is fixed on exterior surface at central line of lon radius arc of the stator. Fi.1 Diaram of the Transmission System Fi. Structural Diaram of the Element The oil dischare port and oil entry port of the secondary element are the same in size. Vanes are placed radially on the rotor (placin anle is zero). The stator may rotate around its center by drivin of the variable piston. When the secondary element does not work, the central line of the lon radius arc of the stator superposes central lines of a roup of oil-distributin windows. The rotor is in initial position (zero point) and the displacement of the secondary element is zero. When the stator rotates clockwise or counterclockwise, the rotary anle increases and the displacement of the secondary element also increases. When the rotary anle reaches to 45º, the placement of the secondary element is maximal. When the rotary anle is neative 45º, the neative displacement of the secondary element is maximal. As the stator rotates within the rane between neative 45º and positive 45º, the displacement of the secondary element chanes continuously. Position relation between the distributin trays and the stator can be reulated by the variable 16

3 International Journal of Research in Mechanical Enineerin Volume-, Issue-6, November-December, 014, (O) (P) cylinder rotatin the rotor of the secondary element. Accordinly, sizes and positions of windows for oil dischare and entry are chaned to achieve chanes of flux and oil flowin direction. In workin, the position sensor checks the rotary anle of the stator and feeds back it to the controller. The controller ives instructions to the electro-hydraulic valve to reulate the displacement of the piston. 3. MATHEMATIC MODELS OF THE SYSTEM Accordin to structural form of the secondary reulatin transmission system for the bus, we et its closed loop pane diaram of system basin on mathematical models of the electro-hydraulic servo valve and all parts of the secondary reulatin transmission system. 3.1 Dynamic Mathematic Model for the Electro-Hydraulic Servo Valve In this system, the natural frequency of the electro-hydraulic valve is hih that is much hiher than that of the variable cylinder of the secondary element. So, the system can be looked as a proportional process [3]. We have: Q sf ( s ) K (1) v I ( s ) where, K v is flow ain of the servo valve, Q s is output flow of the servo valve, I is input current of the servo valve. 3. Mathematic Models for the Double-Actin Vane-Type Secondary Element 3..1 Flux continuity equation for the variable cylinder dx Vt dp q A C t p () dt 4 e dt where, q is flux that enters into the hih-pressure cavity of the variable cylinder, A is effective area of the piston of the variable cylinder, x is the displacement of piston of the variable cylinder, C t is the total leakin coefficient of the variable cylinder, p is the pressure difference between the hih pressure cavity and the low-pressure cavity, V t is the total volume of two cavities of the variable cylinder, β e is volume modulus of elasticity. 3.. Force equilibrium equation for the variable cylinder and load A p d x dx m1 B1 k1x F f (3) dt dt where, m 1 is the total mass of load, piston rod and piston components, B 1 is viscous dampin coefficient, k 1 is the sprin stiffness of the centerin sprin in the variable cylinder, F f is the exterior resistance of the piston of the variable cylinder Displacement of the secondary element D D max x (4) X max where, D is volume, D max is the maximum displacement of the element, X max is the maximum displacement of the variable cylinder. 17

4 International Journal of Research in Mechanical Enineerin Volume-, Issue-6, November-December, 014, (O) (P) Torque equilibrium equation for the secondary element and load d d p s D J B M L dt dt (5) where, p s is the pressure of the system, J is moment of inertia of rotary parts of the element, θ is the rotary anle of the rotor of the secondary element, B is the viscosity damped coefficient of the secondary element, M L is the exterior load torque of the secondary element. 3.3 Mathematical Model for the Transmission System Equilibrium equation for drivin force of the bus If aerial resistance is nelected, the equilibrium equation for drivin force is showed below. d y F 1 F m mf( cos sin ) (6) dt where, F 1 is the drivin force of the enine, F is the drivin force of the secondary element, m is the total quality of bus and load, is the acceleration of ravity, y is the displacement of the bus, f is the rollin friction coefficient, β is the anle of the slope Load torque equation for mixin power bus transmission system r r M L F1 F (7) i1i i1i3 Here, i 1 is the transmission ratio of the rear axle of the bus, i is the speed ratio of the earbox, i 3 is the transmission ratio of the transmission device, r is the radius of the tyre Displacement equation for the bus The displacement equation for the bus is available from relation between the displacement of the bus and the rotary anle of the rotor of the secondary element. r y (8) i 1 i Closed Loop Model of Power Feedback for the System After Laplace transform, simplified process and combined process, the pane diaram of closed loop control for constant power feedback is available [4]. It is showed in Fi. 3. Fi. 3 Closed Loop Pane Diaram of Double Feedback Systems 18

5 International Journal of Research in Mechanical Enineerin Volume-, Issue-6, November-December, 014, (O) (P) PERFORMANCE SIMULATIONS We take one type bus as the simulation object. Main parameters of the double-actin vane-type secondary element are as below: the nominal pressure is 16MPa; the max pressure is 0MPa; the max displacement is m 3 /r; the max rotary speed is 150 r/min; and the max rotary anle of stator is ±45º. Control rule adopts fuzzy-neural network [5] control arithmetic as Fi. 4. Fi.4 Fuzzy Neural Network Control System Simulation Diaram We can acquire the simulation curve of velocity, torsion and power of enery-conservation brake of constant power control [6] as Fi. 5, Fi. 6 and Fi. 7 respectively shows. From simulation curves of speed, torque and power, we can find some features of the constant power control enery-savin brakin. The double-actin vane-type secondary element can reclaim the brakin kinetic enery. Because the constantpower controlled enery-savin brakin indirectly controls the brakin torque, acceleration in initial brakin phase can be controlled by choosin the value of power. In the initial phase and most time of the constant-power brakin, the brakin torque continuously chanes with slow chane speed. So, when the constant-power enery-savin brakin is used, the brakin at hih speed is stable and there is not acceleration siltation in most brakin time. Torque chane is reat at evenin phase. Particularly, when the chosen brakin power is bi, the impact brakin torque appears. In the constant-power enery-savin brakin, the recycle efficiency of enery can be increased by choosin bi brakin power. Fi. 5 Curve of Speed Fi. 6 Curve of Torque Fi. 7 Curve of Power 19

6 International Journal of Research in Mechanical Enineerin Volume-, Issue-6, November-December, 014, (O) (P) CONCLUSION When the brakin power is bi, the brakin torque of the secondary element is bi. And, brakin time is little and brakin distance is short. So, enery consumed by road resistance is little and recycle efficiency of the enery is hih. Contrarily, the recycle efficiency of the enery is low. If the constant-power control form is used to recycle brakin enery of the bus, at hih speed, outputtin brakin torque of the secondary element and brakin force of the bus are little, in the process of brakin, the brakin torque chanes smoothly, which can ensure safety at hih-speed brakin and uprade seatin comfort, and it not only recycles inertial enery of the bus and decreases desin power of the system, but also reduces mechanical wear of the bus and environmental pollution. 6. ACKNOWLEDGEMENT This work was supported by Shandon Province Natural Science Foundation (ZR011EEM03). REFERENCES [1] Jian,J. H.. Hydrostatic Transmission Technique with Secondary Reulation. Hyd. Pneum.& Seals, Vol.17 (000),pp.3. [] Jian,J. H., Zhao,C. T., Men, Z.S.. Study on Enery Recovery Method in Automobile System of Hydrostatic Transmission with Secondary Reulation. China Mechanical Enineerin, Vol.1(001),pp.71. [3] Zhao, C. T., Jian, J. H., Zhao, K. D.. A Study on Hydrostatic Transmission with Secondary Reulation and its Applications to City Bus. Automotive Enineerin, 001,3(6) : 43~46. [4] Jian,J. H.. Hydrostatic Closed-loop Position System with Secondary Reulation and its PID Control. Construction Machinery and Equipment, 000,31(5) :6~9 [5] M.Y. Kim, CO. Lee: Control Enineerin Practice. Vol. 14(006), p [6] J.B.Hu, X.L.Guo and S.H.Yan. Dynamic characteristics of hydrostatic secondary control load simulation system and the approach to resist load disturbance[j]. Transactions of the Chinese Society for Aricultural Machinery,Vol.39(008),p: