Class #22Pump Displacement Control

• Reading Questions• Pump Control Methods• Displacement Control• Controlling Multiple Actuator Systems

ME 8243: TOPICS IN DESIGN:ADVANCED FLUID POWER

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Reading Questions

• Reading: Heybroek thesis:Displacement Control

• Reminder: Progress reports due Tuesday

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Pump Control Classification

Source: M. Ivantysynova

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Pressure Compensation

Direct hydraulically operated and controlled

Source: M. Ivantysynova

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Pressure Compensation

One variable hydraulic resistance

Source: M. Ivantysynova

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Pressure Compensation

Two variable hydraulic resistances

Source: M. Ivantysynova

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Load SensingHow does it work?

Source: M. Ivantysynova

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Load Sensing

Source: M. Ivantysynova

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Pump Requirement ComparisonWhat is pump P & Q for:1. Fixed pump2. Pressure compensated pump3. Load sensing pump

Actuator 3

Actuator 2

Actuator 1

Pressure

Actuator 3 RequirementAct

uato

r 1 R

equi

rem

ent

Actuator 2 Requirement

Pmax

Qmax

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Are there alternatives to valve control?

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Displacement Control: Single-Ended Cylinder

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Alternative Approaches to Differential Cylinder

Source: Quan, Z., Quan, L., and Zhang, J., 2014, “Review of energy efficient direct pump controlled cylinder electro-hydraulic technology,” Renewable and Sustainable Energy Reviews, v. 35, p. 336-346.

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Displacement Control: Shared Low Pressure

Source: M. Ivantysynova

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Degrees of Freedom of Excavator

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Exercise: Multi-Actuator Control1. Circuit diagram & size load sensing circuit2. Circuit diagram & size displacement control circuit3. Design circuit of your choice 4. Compare efficiency of the three circuits:

a. Boom extending at 0.1 m/s with extension force of 150 kN, Swing stationary.

b. Boom retracting at 0.05 m/s with an extension (over-running) force of 50 kN, Swing rotating at 8 rpm with a torque of 100 kN*m

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How to Choose Circuit Architecture?

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18Source: M. Ivantysynova