Pumps for Mini Excavators

Abstract

The invention relates to a pump for a compact excavator. The pump comprises a main pump body and a rotary pump body as well as a power control valve, a load sensitive valve and a pressure cut-off valve which are connected with the main pump body; the power control valve is provided with a rotary valve spool, a valve bush, a power lever, a power valve spool and a spring preload mechanism; the power lever is L-shaped with one side contacting with the right end of the rotary valve spool while the other side contacting with the left end of the power valve spool; the right end of the power valve spool is in contact with the spring preload mechanism; an oil port of the load sensitive valve is communicated with an oil port of each of the pressure cut-off and the power valve; a servo piston contacts with the bottom of the power lever through a push rod, hydraulic oil acts on the push rod through a small hole of the servo piston and then acts on the power lever, and an oil outlet of the rotary pump body leads pressure oil to act on the rotary valve spool to enable total power to be constant; the rotary pump body is in series connection with the main pump body, and an oil inlet of the rotary pump body is connected with an oil tank while the oil outlet of the same is connected with a rotary bulldozing loop. The pump is low in manufacturing cost, high in stability and good in reliability.

Description

technical field [0001] The invention relates to the technical field of mechanical manufacturing, in particular to a pump for a small excavator. Background technique [0002] At present, the common small excavators in the market are driven by a hydraulic plunger pump, and its control mode is load sensing and power control. The load sensing valve in the pump controls the pump output flow by comparing the pump outlet pressure with the pressure from the system. When the excavator of this system is actually working, there will be a situation. For example, when the boom is lifted and rotated at the same time, because the demand flow of the system suddenly increases, the output flow of the pump is not enough, that is, the undersaturated state. When the load sensing valve and compensation valve in the system work, the output flow of the pump is distributed to each action in equal proportion, so some actions will be particularly slow, such as the rotation process, resulting in the l...

AI Technical Summary

Problems solved by technology

When the excavator of this system is actually working, there will be a situation. For example, when the boom is lifted and rotated at the same time, because the demand flow of the system suddenly increases, the output flow of the pump is not enough, that is, the undersaturated state. When the load sensing valve and compensation valve in the system work, the output flow of the pump is distributed to each action in equal proportion, so some actions will be particularly slow, such as the rotation process, resulting in a longer working cycle.

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