Container transportation is a kind of advanced modern transportation mode in cargo transportation. 10. It is characterized by “safe, rapid, simple, and inexpensiveâ€, which helps to reduce the transportation links. It can make comprehensive use of various types of railways, highways, waterways, and aviation. The mode of transport, multimodal transport, to achieve "door to door" transport.
The container straddle carrier is a kind of “door-to-door†container handling machinery, which generally adopts the form of full hydraulic transmission, and uses the engine and hydraulic system to realize functions such as system travel control, lift control, steering control, and brake control. The existing "door-to-door" transport problem.
Container cross-vehicles are mostly used in container terminals and transfer station yards. Their role is to achieve horizontal transportation, stacking and loading and unloading of containers. It has the characteristics of flexibility, high efficiency, good stability, and low wheel pressure. There are many container terminals adopting this technology in developed countries in Europe and the United States, such as Rotterdam in the Netherlands, Hamburg in Germany, Southampton in the UK, Durban in South Africa, and Brisbane in Australia. In addition, Duisburg inland containers The wharf also began to use the cross-vehicle process. 0. Currently, there are many container handling equipment manufacturers at home and abroad that produce light-duty container straddle carriers. Italy's Ferrari Container Runner container straddle can easily switch between 'stack over one' and 'zero over' status, and can adapt to different operation needs. The straddle carrier produced by Swedish Kalmar company is generally used. The container is transported in the middle of a short distance, which is flexible and fast. The system is fully hydraulically driven and is widely used in large European terminals.
In the future, with the promotion of the use of container trucks in port applications, the number will definitely increase. However, the resources consumed by a large number of container trucks and the pollutants discharged from them have an unpredictable load on the environment. At this stage, higher requirements have been placed on the energy efficiency and environmental protection of port loading and unloading equipment.
At the end of the 20th century, Western countries formulated a series of policies to limit the noise, emissions, vibration, and other indicators of the loading and unloading equipment. In the "Eleventh Five-Year Plan", China also explicitly proposed energy conservation, consumption reduction and anti-pollution. The goal of emission reduction. With the enhancement of people's awareness of environmental protection, the study of environmental protection and energy-saving measures in the application of container straddle carriers is imperative, and it is also the trend of the development of container handling equipment in the future.
Most of the existing container straddle carriers use the full hydraulic drive form. If the hydraulic system design is unreasonable, the energy lost due to flooding during the work process reduces the operating efficiency of the system, and on the other hand, the loss of energy is converted into heat. Raising the temperature of the working fluid reduces its viscosity, increases the amount of system leakage, and at the same time also reduces the service life of the fluid and deteriorates the performance of the engine oil.
2 Load-sensitive energy-saving technologies Container cross-trucks are mainly composed of a frame, a traveling system, a hoisting system, a steering system, a braking system and a power drive system. The power drive system generally adopts the form of a hydraulic system of a diesel engine. The diesel engine drives a variable displacement pump to generate high-pressure oil, and the mechanical energy is converted into hydraulic energy. The hydraulic energy directly drives the wheel-side motor, lift cylinder, steering cylinder and the like through a multi-way valve group. Brake, hydraulic energy is converted into mechanical energy, such as.
Diesel engine-hydraulic system power drive system model However, in the hydraulic system design of full-hydraulic container straddle carrier, the power of the diesel engine must meet the maximum power and flow requirements under all normal operating conditions, and has a fixed power reserve, but across When the power and system flow of the hydraulic system required by a truck under a certain working condition are much smaller than the design value, most of the system flow is overflowed, resulting in a decrease in the system power utilization rate; and the increase in the overflow flow rate. Larger, higher oil temperatures, lower viscosity, and reduced system drive efficiency.
The power-driven system based on load-sensitive technology is an important means to improve the power efficiency of the straddle carrier. It is a kind of hydraulic circuit that senses the system pressure-flow demand and provides only the required flow and pressure, and can automatically be based on external loads and speeds. The changes provide stable pressure and flow for the traveling system, lifting system, steering system, and brake system, reducing the overflow loss caused by changes in pressure and flow, and improving the drive efficiency of the power drive system.
Straddle truck load-sensitive hydraulic system (see) mainly consists of load-sensing pump, quadruple multi-way valve group, wheel-side motor, hoist cylinder, steering cylinder, brake valve group, brake, fixed pump and other components. The load-sensing pump consists of pressure limiting valve and LS control valve. The multi-way valve group consists of a main valve block and a four-work valve block, including a pressure compensation valve, a proportional directional valve, a shuttle valve and an overflow valve, and a wheel-side motor. Lift cylinders, steering cylinders.
The actual working state of the load-sensing hydraulic system of the straddle carrier mainly includes the idle state of the hydraulic system and the normal working state of the traveling system, the hoisting system, the steering system, and the braking system.
When the straddle carrier actuator stops working and the load-sensing hydraulic system is in idle state, the LS control valve has no pressure signal, the variable pump unloads through the valve, and simultaneously pushes the pump swash plate back to the neutral position, the displacement of the pump is approaching. At zero, the hydraulic system is in a state of low pressure and low flow.
Main valve block control system's total oil pressure; proportional directional valve can accurately control the action of the actuator; shuttle valve to transmit the various work valve block 1. wheel side motor 2. lift cylinder 3. steering cylinder 4. quad multi Valve manifold 5. Load sensing pump 6. Brake valve assembly 7. Brake 8. Dosing pump Pressure signal across truck-load sensitive hydraulic system to LS output to adjust pump displacement; The maximum working pressure of the working valve block; the pressure compensating valve can play the role of keeping the output flow constant when the working load of each system changes; the LS output port is the pressure output port of the load and outputs the maximum pressure value in the working valve blocks of each joint.
When the walking system, lifting system, steering system and braking system work normally, the valve position of the proportional directional valve is at a certain working position. The flow rate provided by the hydraulic system is the same as the required flow of each system, and the output pressure of the load-sensitive pump Equal to the sum of the load pressure and the spring force of the LS control valve, the spool is in dynamic equilibrium and the pump displacement remains constant.
3 Conclusion Container-driven straddle carrier adopting advanced load-sensitive energy-saving technology can achieve stepless speed change, stable and reliable operation, light and flexible operation, safe and reliable, high operating efficiency, and its load-sensitive hydraulic system can adjust the pressure of the pump according to load conditions and Flow, so that the output flow of the hydraulic pump just to meet the load change requirements, and the oil pressure is only slightly higher than the load pressure, to achieve the purpose of saving energy in the hydraulic system, in line with China's port loading and unloading equipment, energy saving and pollution prevention and emission reduction of the overall requirements.
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