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Electro-hydraulic control design for pump discharge pressure control

A pressure control and hydraulic technology, applied in the hydraulic field, can solve problems such as damage

Inactive Publication Date: 2015-05-20
CATERPILLAR INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Also, because the fan drive system has a large inertia, the displacement control pump can be exposed to low pump discharge pressures that can damage the pump and / or other components of the associated hydraulic system

Method used

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  • Electro-hydraulic control design for pump discharge pressure control
  • Electro-hydraulic control design for pump discharge pressure control
  • Electro-hydraulic control design for pump discharge pressure control

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0016] Hydraulic fan systems typically employ a hydraulic motor to drive an associated fan. In this embodiment, hydraulic fan control may be modeled as a function of motor torque and fan torque due to the drive pump discharge pressure. The torque loss on the fan mainly comes from the friction torque loss and the torque loss caused by the wind force, wherein the friction torque includes Coulomb friction torque and viscous friction torque. The friction torque can be expressed as:

[0017] T f = c cf P p +c vd ω F (1)

[0018] Among them, C cf is the Coulomb friction constant, C vd is the viscous damping coefficient. W f is the fan speed, and P p is the pump discharge pressure. It should be noted that friction torque is related to pump discharge pressure and fan speed. The torque loss due to this wind force can be expressed as:

[0019] T w = c wd ω F ...

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PUM

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Abstract

An electro-hydraulic control system manages speed of a hydraulic fan by using a solenoid to bias a three position pool of a control valve coupled to a hydraulic pump driving the fan. In a first position, the spool releases pressure on a de-stroke actuator of the pump and allows an on-stroke actuator to increase output pressure corresponding to a speed of an engine driving the pump. In a second position, the spool isolates the de-stroke actuator and fixes the pressure output of the pump. In a third position, the spool couples the de-stroke actuator to the pump output and causes a reduction in the pressure output of the pump. The solenoid coupled to the spool sets the output pressure at which the spool is in the second position.

Description

technical field [0001] The present invention relates generally to hydraulics, and more particularly to a hydraulically operated piston pump. Background technique [0002] Hydraulic fluids are used to produce useful work in a variety of machines. To provide hydraulic fluid to drive the drive cylinders or the engine, one or more hydraulic pumps are typically provided on the machine, which are driven by the machine's engine. Such pumps can be provided in many different forms, with an axial piston pump being a common embodiment. Using an axial piston pump, the motor rotates the center barrel or center block. The barrel includes a plurality of cylinders, each adapted to receive a reciprocating piston. At the driven end, each of the pistons pivotally and slidingly engages an angularly positioned baffle relative to the cylinder bore. At the working end of each cylinder, a valve plate with two or more inlets and outlets is set. During the entry phase of operation, hydraulic flu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F04B35/04F15B13/044F04B27/08F02D29/04
CPCF01P7/044F02D29/04F04B35/04F16H61/431
Inventor H·杜
Owner CATERPILLAR INC