Energy regeneration type forklift hydraulic system

Abstract

The invention relates to an energy-saving forklift hydraulic system with an energy recovery function. The forklift hydraulic system comprises an oil tank, a check valve, a first oil pump, a multi-way valve, two lifting oil cylinders, two tilt oil cylinders, a steering oil cylinder, a load-sensing steering device, a second oil pump, a motor, a speed limit valve and a direction control valve, wherein the multi-way valve consists of an oil inlet-return valve plate, a lifting change valve plate, a tilt change valve plate and an oil inlet valve plate; the check valve and a main safety valve are arranged inside the oil inlet-return valve plate; the lifting change valve plate comprises a lifting three-position six-way change valve, an oil return duct and an oil duct; the tilt change valve plate comprises a tilt three-position six-way change valve, a first overload oil supplement valve and a second overload oil supplement valve; and the oil inlet valve plate comprises a flow divider valve, a priority valve and a steering safety valve. The forklift hydraulic system can utilize the potential energy of cargo to simultaneously drive two oil pumps for driving two motors to generate electricity, thereby realizing energy recovery; or one part of potential energy is converted to hydraulic energy by one oil pump and surplus differential pressure also can be regenerated for electricity generation, while the other part is used by the other oil pump to drive the motor for generating electricity, so that energy recovery is realized.

Description

technical field [0001] The invention belongs to the technical field of forklifts, and in particular relates to hydraulic systems of forklifts. Background technique [0002] The forklift uses the lifting system to complete the processes of picking up, lifting, stacking, and stacking the goods. When the forklift is picking up goods and descending, it uses various throttling methods to control the descending speed of heavy objects. In this process, the gravitational potential energy is all converted into heat energy through the throttle valve. It will not only cause the temperature rise of the hydraulic system, but also affect the reliability of the system and components and the working efficiency of the whole vehicle. With the increasingly tense international energy supply and the increasing awareness of environmental protection worldwide, green and energy saving have become the future development trend of technologies and products in various industries. The development of ...

AI Technical Summary

Problems solved by technology

The foreign forklift lowering energy recovery system we know is to meet the switching requirements of the lifting and lowering working oil circuit through an external group or two groups of electromagnetic reversing valves, and generally uses a single pump to generate electricity, which requires a large displacement of the oil pump and a large motor power. high cost

Patent No. ZL 201120038176.8 "Hybrid Power Forklift Hydraulic System" and Patent No. ZL 201120038177.2 "An Energy-Saving Hydraulic System for Electric Forklifts" are technical solutions: the lifting valve plate is additionally equipped with a Pt port to solve the problem of the oil cylinder descending oil circuit; the pilot pressure oil circuit is used to To control the hydraulic control sequence valve to meet the requirements of power generation under different load conditions, the power generation mode is determined according to the load condition; the power generation is driven by a single pump, which requires a large displacement of the oil pump and a large motor power; the lifting tilt is controlled by a safety valve , but the actual working pressure of tilting is low, the work is frequent, there is only one pressure setting, and the system loss is large; the brake system is supplied by a separate oil pump, and the manufacturing cost is high

Although the technical solution described in Patent No. ZL 200920200479.8 "Hydraulic System for Forklifts" solves the problems associated with braking and steering through priority valves and diverter valves, since the braking and steering are realized by the oil supply of two oil pumps, once the forklift starts to work , two oil pumps are required to work at the same time, and the power loss of the system is large; the hydraulic oil output by the two oil pumps in the technical solution respectively passes through the priority valve and the diverter valve and merges through the EF oil circuit, and then supplies oil to the lifting cylinder and the tilting cylinder to realize cargo. The lifting and tilting of the fork, when the actual forklift is working, the flow required for lifting is large, while the flow required for tilting work is small, so the dual-pump oil supply needs to be set in the multi-way valve or pipeline to control the forward and backward tilting speed. The pressure loss is large and the temperature of the hydraulic system rises

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