Analysis of Hydraulic System of Double Cylinder Straight Roof Hydraulic Elevator

2 Abstract Two kinds of throttling speed control hydraulic systems are analyzed, and the control strategy of the throttle throttle speed control system is proposed.

1 Introduction Hydraulic elevators are safe and comfortable vertical transportation equipment in multi-storey buildings. They are also the cheapest heavy-duty vertical transportation equipment in factory warehouses. They are electro-hydraulic fluids and consist of several relatively independent and coordinated subsystems. Compared with the electric traction elevator, the hydraulic elevator has the advantages of no need to install the machine room at the top, compact structure, large capacity, stepless speed regulation, stable operation and low cost. Widely used in developed countries, with the advent of society. The hydraulic ladder will enter thousands of households.

According to the hydraulic system flow control, the hydraulic circuit of the special hydraulic elevator can be divided into volume control, throttle control and compound control, and the main control, which is widely used in the elevator. system. This paper analyzes the effects of practical applications by comparing the hydraulic systems of two hydraulic elevators, and tries to find a hydraulic system for hydraulic elevators that have good performance in China.

2 Analysis of the operating characteristics of the hydraulic elevator In the hydraulic elevator speed control system, the car is started for its running performance. There are high requirements for accuracy and speed of acceleration and deceleration, and the speed acceleration of hydraulic elevators and the maximum value of jerk are strictly limited. Reflecting the operating law of the hydraulic elevator, it is usually shown by the speed curve. The whole hydraulic elevator operation process can be divided into 5 stages 1 plus, stage 012 magic speed stage 83 deceleration stage set 4 layers stage 5 end stage VR1 3 comparison of two hydraulic systems 3.I bypass throttle adjustment, system 3.1.1 System principle switch 19 pressure 20 still pressure oil filter 18 check valve 3 electromagnetic overflow called 4 屯 magnetic proportional speed regulation 5. liquid bridge 9, 10 electromagnetic proportional throttle valve 7, 8 electronic control check valve, 12 hydraulic cylinder 13,14 manual lowering valve 15 is composed of oil return filter 16. The elevator adopts bypass throttling speed regulation in the uplink and the oil return throttling speed regulation in the downlink.

When the normally open electromagnetic spill valve is powered off, the hydraulic pump is unloaded. When the elevator is running up, the solenoid valve is energized, so that the system can build the electromagnetic proportional speed control valve, the bypass speed regulation when the elevator rises, and the oil speed regulation when the elevator is lowered.

Electromagnetic proportional throttle valve for dual-cylinder synchronous control. One is the master control valve and the other is used to follow the synchronous control. Since the proportional throttle valve can only pass oil in one direction, a hydraulic bridge is added to make the proportional throttle valve work normally when the elevator is running up and down.

Manual throttling. The standby electronically controlled check valve is used for system debugging, and the electronically controlled check valve has the function of preventing the car from being settled and the power is locked.

The manual lowering valve, also called the emergency valve, can operate the manual lowering valve to lower the elevator at a lower speed 18 when the power grid suddenly loses power or the hydraulic system cannot operate due to a fault. The manual lowering valve is designed in a two-cylinder linkage.

After the system receives the upstream command, the electromagnetic spill valve is energized to establish pressure on the system. During the start-up phase of the elevator, the proportional speed control valve is controlled by the computer so that its opening degree is gradually reduced from the maximum, and the speed of the elevator is gradually increased by 1 liter, and the deceleration phase is similar. By controlling the flow through the proportional speed control valve, the elevator is operated according to the ideal curve, and finally the leveling station stops. The electromagnetic relief valve is unloaded due to the foot double cylinder system. By adjusting the two proportional throttles to ensure that the flow rate of the two forward cylinders is equal.

Thereby synchronizing the movement of the two cylinders.

When the elevator goes down, after the system receives the down command, the proportional speed control valve is first turned off, and the two electronically controlled single valves are electrically sweated. The opening of the proportional proportional speed control valve is gradually increased, and the hydraulic oil in the hydraulic cylinder is proportional. The throttle valve flows through the proportional speed control valve and flows back to the fuel tank. By controlling the flow through the proportional speed control valve, the elevator is lowered according to the ideal curve. The two cylinders are simultaneously lowered by adjusting the two proportional throttle valves.

The principle of the bypass throttling speed control hydraulic system 2, the system consists of the box 21 oil filter 17 motor 2 pump 1 card force clothing. , 0 gK, because the pressure of the hydraulic pump changes with the load, the leakage of the hydraulic pump also changes, resulting in the change of the actual output flow of the hydraulic pump, which makes the stiffness of the system smaller, which will cause the instability of the actuator movement. As the throttle opening is large, the maximum load that the system can withstand will be reduced, that is, the load carrying capacity at low speed will be small. Compared with the oil inlet throttling and oil return throttling speed control system, its speed regulation range is small.

1 chest; motor; 3 check valve; 4 electromagnetic overflow weir; 5 proportional relief valve; 6 manual throttle; 7.8 proportional throttle, 9. hydraulic bridge 12 electronically controlled check valve; 13.1 + cylinder; 15 manual drop valve; 1 oil filter; 17 oil filter; 18 high pressure oil filter; 19 pressure switch; 20 pressure; 21 fuel tank 3.2 oil throttle throttle speed control system 3.2.1 system principle The principle of throttling speed control hydraulic system 3, the system consists of oil 筘 1 into 1 oil filter 23. Pump 3 motor 4 pressure switch 5 pressure 6 high pressure oil filter 7 check valve 8 proportional relief valve 9 electronic control, to valve. 12 proportional throttle 13 proportional speed regulating valve 14 hydraulic bridge 15, 16 manual lowering valve 17 hydraulic cylinder 18, 19 oil return filter 20 composition.

When the elevator is running, the hydraulic cylinder 19 is the main cylinder, and the opening of the proportional speed control valve 14 is controlled to ensure that the car is bent at a predetermined speed, and the ferrite tank is a ship of the oil, and the oil is filtered. Motor 5 pressure clamp 6 pressure; 7 high pressure oil filter; one-way; 9 proportional relief valve; 1012 electronic control one-way 13 ratio 7 flow 陬 14 proportional speed control valve; 1516 liquid 1; bridge; 17 manual drop valve ; 9 hydraulic cylinder; 2 return oil filter cylinder 18 speed to reduce the height difference between the two cylinders, thus ensuring twin-cylinder synchronization. Other valves function the same as in the system.

When the proportional relief valve proportional solenoid valve is de-energized, the hydraulic pump is unloaded. When the elevator is running up, the pressure of the overflow is determined according to the detected oil pressure signal, so that the pressure of the proportional relief valve is adjusted according to the load condition, thereby reducing the power loss.

The electromagnetic proportional speed control valve is used as the main valve, and the oil inlet speed is adjusted when the elevator rises. 1 When the time is lowered, the speed of the road is reduced.

The electromagnetic proportional throttle valve acts as a slave valve, following the main valve to ensure the synchronization of the two cylinders. Since the proportional throttle valve and the proportional speed control valve can only pass oil in one direction, a hydraulic bridge is provided, so that the proportional throttle valve and the proportional adjustment when the elevator is running, the valve can be normally used, and the electronically controlled check valve The function of the manual lowering valve is the same as above.

3.2.2 System characteristics, the activity of live cold movement is proportional to the flow area of ​​the turbulent flow, that is, the larger the flow area, the more the piston movement violation is affected by the load change due to the flow entering the hydraulic cylinder, and the speed is stable.

3.2.3 Two adjustments, the power loss of the system is compared with the power loss of the hydraulic elevator. The acceleration phase of the acceleration phase of the elevator is in the reverse phase and the end phase. This stage is the non-hooking phase, and the speed of the elevator is always less than the maximum.

For the plant into the throttle throttle control system, the flow from the hydraulic pump has to pass through the proportional relief valve, and the flow through the proportional relief valve in the acceleration phase follows the speed synchronization closed loop =, scare 1 sink Degree, plus and gradually decrease. In other stages, as the speed of EHSfiHSaSMBHSS decreases, the power loss is the product of the overflow pressure and the overflow flow. Since the inlet throttle throttle hydraulic system adopts a proportional relief valve, its overflow pressure is small according to the load power detected by the pressure sensor, and the system efficiency is high.

For the bypass throttle throttle speed control system, in the non-uniform speed phase, the flow rate of the hydraulic pump is partially passed through the proportional speed control valve, and the flow rate flowing through the proportional speed control valve in the acceleration phase is gradually reduced as the speed increases. In other 1. stages, the speed gradually increases with the decrease of speed. The power loss is the pressure at the inlet of the proportional speed control valve. If the pressure drop of the valve in the system is neglected, the pressure at the inlet of the proportional speed control valve is the load pressure and flow. The product of the proportional speed control valve flow.

In the uniform speed stage, the throttle pump speed control system, the flow rate of the hydraulic pump all pass the proportional speed control valve and the proportional throttle valve, and the hydraulic flow + interface of the bypass oil passage throttle speed control system is called a proportional section. Flow valve, the power loss of the two systems is basically the same in the constant speed phase.

The hydraulic elevator relies on its own weight to descend, and both systems are oil return throttle speed control systems with the same power loss.

From the above analysis and comparison, it can be seen that the power loss of the throttle throttle adjustment system and the bypass throttle throttle speed control system differs a lot when the elevator is going up, but the throttle pipeline throttles the system to adjust the violation performance. It is much better than the throttle control system of the poor oil road. This is also the main reason why we choose the throttle control system.

3.2.4 Analysis of control strategy In order to ensure the ride comfort of the elevator, it is necessary to make the car different according to the characteristics of the set throttle valve. The pipe arrangement is different, the load of the two hydraulic cylinders is not the same, and the speed of the hydraulic cylinder 1819 is The difference, therefore, the elevator command speed control closed-loop control system can be divided into two closed-loop speed control closed loop and step closed loop.

The structure of the control system is shown in Box 4.

4 conclusion system, it achieves speed regulation, system and two-cylinder synchronization system through the combination of proportional speed regulation 1 and proportional throttle 1 call. The power loss of the bypass throttle throttle speed control system and the bypass oil throttle throttle speed control system is almost the same, but its speed regulation performance is much better than that of the bypass oil throttle throttle speed control system. With the 屯, the check valve realizes that the liquid scent elevator does not settle. In addition, the manual lowering valve can ensure that the car can be lowered to a safe position when the elevator fails. The most 0 proposes the use of microcomputer as the core to realize the speed and synchronization control of 1mm double-cylinder hydraulic elevator. Dr. Shanghai Tongji University 1999.2 2 Liu Fucai and other applications of 8031 ​​single-chip microcomputer in hydraulic elevator control system Zhao Guojun Yang Huayong multi-mode fuzzy control theory The application industry and automation device in the speed feedback hydraulic elevator system 4m Xiao Ziyuan Xu Mingqian two-cylinder straight-top hydraulic elevator hydraulic control system analysis China elevator 1998,5 to use synchronous control technology to ensure the motion synchronization of the two cylinders. The author is often reached. Graduate student, male, Department of Mechanical Engineering, Tongji University. 200092