A lift valve piece of a forklift electro-hydraulic proportional multi-way valve

Abstract

The invention relates to the technical field of engineering machine hydraulic elements, in particular to a lifting valve plate of an electric-hydraulic proportional multi-way valve of a forklift. The lifting valve plate can achieve full-speed descending of a single-acting cylinder and secondary pressure of the multi-way valve. The lifting valve plate comprises a valve body, an overflow valve, a backpressure valve, proportional electromagnetic valves, a compensation valve, a reversing valve rod and end covers. A pressure difference formed between a pilot oil inlet and a pilot oil return opening in a valve element of each proportional electromagnetic valve is introduced into cover cavities to push the reversing valve rod to move left and right. A first oil way, a work oil opening and an oil inlet trough are arranged in the valve body, and one end of the oil inlet trough communicates with the first oil way. A valve element of the compensation valve is located in the oil inlet trough. The first oil way is provided with a main oil return opening, and the backpressure valve is arranged on the valve body. A second oil way is arranged on the valve body and connected with the overflow valve and the backpressure valve. A first cavity and a second cavity are formed in the reversing valve rod, and a first small throttle hole and a third small throttle hole are formed in the peripheral wall of the reversing valve rod.

Description

technical field [0001] The patent of the invention relates to the technical field of construction machinery hydraulic components, in particular to a lifting valve plate of a forklift electro-hydraulic proportional multi-way valve. Background technique [0002] With the rapid development of modern science and technology and the continuous popularization of forklifts, people are not only satisfied with the function of forklifts, but also put forward high requirements for work efficiency, work accuracy and operator comfort. The performance requirements of hydraulic multi-way valves for core components are also getting higher and higher. Electro-hydraulic proportional multi-way valves have become a future development trend due to their advantages in high control precision, flexible installation and use, and strong anti-pollution capabilities. At present, the vast majority of electro-hydraulic proportional multi-way valves used in forklifts in China are imported from abroad. Ther...

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Problems solved by technology

At present, the vast majority of electro-hydraulic proportional multi-way valves used in forklifts in China are imported from abroad. There are two problems in use. Electro-hydraulic proportional multi-way valves are used in double-acting cylinder hydraulic systems because of their integrated load-sensing systems. , while domestic forklift lifting systems basically use single-acting cylinders. The lowering of the mast depends on the weight of the load. To use it, the hydraulic system must be modified. Electro-hydraulic proportional multi-way valves are used in single-acting cylinder oil circuit systems, specifically single-acting cylinders. The forklift mast is lowered by its own weight, and the pressure of the load sensing system is always the load pressure. The output pressure of the pump can only push the reversing valve stem for a short stroke, and cannot achieve full-speed descent; Tilting and attachments do not use high pressure, and the existing multi-way valves use overflow valves in the required working unions to achieve the secondary pressure. In this case, installing too many overflow valves will cause cost and The failure rate becomes higher, and the overload valve is not inserted, which causes serious energy waste and heat generation

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