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MapleSim Hydraulics Library from Modelon

Spool_4_3_X  Template for a spool with three positions and four ports to be configured by the user

Use the Spool_4_3_X component to build a custom model of the spool of a directional control valve with three positions (that is, three stable states) and four ports.

Enter the valve behavior in the Parameters  Spool Geometry section (found under the Properties tab ( )) by populating the six connection vectors (open_P_A, open_P_B, open_A_T, open_B_T, open_P_T, and open_A_B). Each vector has nine entries corresponding to the nine normalized spool positions [ -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 ]. Enter a 1 for the spool position if the connection is open at that spool position; enter a 0 for the spool position if the connection is closed at that spool position.

The Example section on this page provides more detail on how to configure a custom spool, including information on setting the parameters for leakage and nominal flow rates between ports.

 

Example

Sketching a Valve

Variables

Connections

Parameters

Example

The following valve sketch will be used for this example:

 

Note: Information on how to sketch a valve is in the Sketching a Valve section on this page.

 

To enter the data for your custom valve into MapleSim

1. 

In MapleSim, under the Libraries tab, browse to Modelon Hydraulics  Directional Control  Basic, and drag a Spool 4 2 X component to the Model Workspace.

2. 

Under the Properties tab ( ), browse to the Parameters  Spool geometry section. The spool position (x-axis) is already given in the vector spool_x_axis with marks at [ -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 ]. Enter values of either 1 or 0 in the vectors open_P_A, open_P_B, open_A_T, open_B_T, open_P_T, and open_A_B. Enter 1 if there is a connection between the ports at the respective position; enter 0 when there is no connection. For this example, the vectors are as follows:

open_P_A = [1, 1, 1, 0, 0, 0, 1, 0, 0]

open_P_B = [0, 0, 1, 0, 0, 0, 1, 1, 1]

open_A_T = [0, 0, 1, 0, 0, 0, 1, 1, 1]

open_B_T = [1, 1, 1, 0, 0, 0, 1, 0, 0]

open_P_T = [0, 0, 1, 1, 1, 1, 1, 0, 0]

open_A_B = [0, 0, 1, 0, 0, 0, 1, 0, 0]

3. 

Specify the nominal value for the pressure drop Δpnom (in the Parameters  Flow section). This value is used to calculate the flow resistance for all six flow paths.

4. 

Specify the nominal data for the flow rates for the six flow paths: qnom_P_A, qnom_P_B, qnom_A_T, qnom_B_T, qnom_P_T, and qnom_A_B. The parameter qnom gives the nominal flow rate of the fully opened flow path at the pressure drop Δpnom.

Amax=qnom12ρk2Δpnom

dmax=2Amaxπ

For example, the maximum diameter for the flow path from P to B is given by dmaxPB:

AmaxPB=qnomPB12ρk2Δpnom 

AmaxPB=qnomPB12ρk2Δpnom 

dmaxPB=2AmaxPBπ

5. 

Enter a value for dleak.

When the valve is closed (both input signals false), there is leakage from P  A, P  B, A  T, B  T, P  T, and A  B. This leakage flow is described by the diameter of an equivalent orifice dleak. If in doubt about the value for dleak, build a small model consisting of a pressure source, an orifice, and a tank and vary the orifice diameter until the required flow rate is reached at the specified pressure.

6. 

Enter values for P_max and coeff_P.

When the pump pressure and the flow rate are high, the unbalanced forces and flow forces acting on the spool are higher than the force generated by the solenoid and the valve is partially closed. This effect can be modeled by the parameters P_max and coeff_P. Specify the maximum hydraulic power in W (where the valve is still completely open) and use coeff_P to adjust the model to the manufacturer's data.

7. 

(Optional) To give your custom valve the correct icon, convert the Spool 4 3 X component to a subsystem, and then draw an icon on the subsystem.

8. 

Save the model and build a small test circuit to compare the catalogue data with the model.

Sketching a Valve

This is a brief discussion on how to generate the connection versus spool position plots for a valve. We will be using the following valve icon as an example.

The preceding figure shows a valve with four ports (A, B, P, and T) and three states based on three spool positions. The connections and flow paths for the three states are given in the following table.

Spool Position

Command signals

Flow paths

-1 (Left square)

commandA=true and commandB=false

Flow from P  A. Flow from B  T.

0 (Middle square)

commandA=false and commandB=false

Flow from P  T.

+1 (Right Square)

commandA=false and commandB=true

Flow from P  B. Flow from A  T.

 

To generate the connection versus spool position plots for a valve

1. 

Redraw your valve icon as three large separate squares (one for each stable position). Include all arrows and lines connecting the ports.

2. 

Sketch two smaller squares for connections between the stable positions (see your valve catalogue for details). The left small square shows the transition between the left stable position and the middle position. The right small square corresponds to the transition between the middle square and right square.

  

Each square also corresponds to a spool position of the custom valve. The left square corresponds to a spool position of -1, the middle square to a spool position of 0, and the right square to a spool position of +1. The left small square corresponds to -0.5 and the right small square to +0.5.

3. 

Draw six horizontal lines representing the 6 possible flow paths: P  A, P  B, A  T, B  T, P  T, and A  B.  The x-axes represent the spool positions [-1..1] and the y-axes the connection state (1 or 0).

4. 

For flow path P  A, sketch the connection as a function of spool position. A 1 means the connection is open, a 0 means there is no connection.

a. 

Left square: if there is flow from P  A (that is, an arrow from P to A in the left square), put marks at x = -1 and y = 1 and at x = -0.75 and y = 1. If there is no flow from P  A (no arrow from P to A in the left square), put marks at x = -1 and y = 0 and at x = -0.75 and y = 0.

b. 

Middle square: if there is flow from P  A, put marks at x = -0.25 and y = 1; at x = 0 and y = 1; and at x = 0.25 and y = 1. If there is no flow from P  A, put marks at x = -0.25 and y = 0; at x = 0 and y = 0; and at x = 0.25 and y = 0.

c. 

Right square: if there is flow from P  A, put marks at x = 0.75 and y = 1 and at x = 1 and y = 1. If there is no flow from P  A, put marks at x = 0.75 and y = 0 and at x = 1 and y = 0.

d. 

Left small square (left intermediate position): if there is flow from P  A, put marks at x = -0.5 and y = 1. If there is no flow from P  A, put a mark at x = -0.5 and y = 0.

e. 

Right small square (right intermediate position): if there is flow from P  A, put marks at x = 0.5 and y = 1. If there is no flow from P  A, put a mark at x = 0.5 and y = 0.

The P  A connection versus spool position plot for the valve in this example is represented in the following figure.

1. 

Repeat the marking process for the other flow paths: P  B, A  T, B  T, P  T, and A  B. For the example used in this section, the connection versus spool position plots for all six connections are represented in the following figure.

Variables

Name

Value

Units

Description

Modelica ID

morPA

 

 

 

mor_P_A

morBT

 

 

 

mor_B_T

morPB

 

 

 

mor_P_B

morAT

 

 

 

mor_A_T

morAB

 

 

 

mor_A_B

morPT

 

 

 

mor_P_T

checkFlow

 

 

 

checkFlow

commanddiameter

 

 

 

command_diameter

portpressure

 

 

 

port_pressure

portflow

 

 

 

port_flow

pPabs

pP+oil.p_atm

Pa

Absolute pressure at port P

pP_abs

psat

[1]

Pa

Gas saturation pressure

p_sat

pAsummary

pA

Pa

Pressure at port A

summary_pA

pBsummary

pB

Pa

Pressure at port B

summary_pB

pPsummary

pP

Pa

Pressure at port P

summary_pP

pTsummary

pT

Pa

Pressure at port T

summary_pT

ΔpPAsummary

pApP

Pa

Pressure drop

summary_dp_PA

ΔpPBsummary

pBpP

Pa

Pressure drop

summary_dp_PB

ΔpATsummary

pTpA

Pa

Pressure drop

summary_dp_AT

ΔpBTsummary

pTpB

Pa

Pressure drop

summary_dp_BT

qPAsummary

mor_PA.q

m3s

Flow rate flowing port_P to port_A

summary_qPA

qPBsummary

mor_PB.q

m3s

Flow rate flowing port_P to port_B

summary_qPB

qATsummary

mor_AT.q

m3s

Flow rate flowing port_A to port_T

summary_qAT

qBTsummary

mor_BT.q

m3s

Flow rate flowing port_B to port_T

summary_qBT

spoolGeometry

 

 

 

spoolGeometry

[1] oil.gasSaturationPressureT=oil.T0+ΔTsystem,vgas=oil.vgas

Connections

Name

Description

Modelica ID

portA

Port A, one of valve connections to actuator or motor

port_A

portB

Port B, one of valve connections to actuator or motor

port_B

portP

Port P, where oil enters the component from the pump

port_P

portT

Port T, where oil flows to the tank

port_T

spoolposition

Command signal for spool position

spool_position

oil

 

oil

Parameters

General Parameters

Name

Default

Units

Description

Modelica ID

flow path A to B

true

 

There is a spool position with flow from port A to B

flowPath_AB

flow path P to T

true

 

There is a spool position with flow from port P to T

flowPath_PT

ΔTsystem

0

K

Temperature offset from system temperature

dT_system

Flow Parameters

Name

Default

Units

Description

Modelica ID

use CheckFlow

true

 

True, if a warning should be printed to user

useCheckFlow

Δpnom

7.·105

Pa

Pressure drop at nominal flow rate qnom

dpnom

qnomPA

0.00158

m3s

Nominal flow rate from P -> A

qnom_P_A

qnomPB

qnomPA

m3s

Nominal flow rate from P -> B

qnom_P_B

qnomAT

qnomPA

m3s

Nominal flow rate from A -> T

qnom_A_T

qnomBT

qnomPA

m3s

Nominal flow rate from B -> T

qnom_B_T

qnomAB

0

m3s

Nominal flow rate from A -> B

qnom_A_B

qnomPT

0

m3s

Nominal flow rate from P -> T

qnom_P_T

Pmax

1.26·105

W

Max. hydraulic power

P_max

coeffP

10

 

Influence of hydraulic power on flow rate

coeff_P

k1

10

 

Laminar part of orifice model

k1

k2

2

 

Turbulent part of orifice model, k2=1Cd2

k2

Spool Geometry Parameters

Name

Default

Units

Description

Modelica ID

dleak

1.67·10-5

m

Diameter of equivalent orifice to model leakage of closed valve

dleak

spoolxaxis

[1]

 

Normalized spool position

spool_x_axis

openPA

[2]

 

Open (1) and closed (0) path P -> A as function of normalized spool position

open_P_A

openPB

[2]

 

Open (1) and closed (0) path P -> B as function of normalized spool position

open_P_B

openAT

[2]

 

Open (1) and closed (0) path A -> T as function of normalized spool position

open_A_T

openBT

[2]

 

Open (1) and closed (0) path B -> T as function of normalized spool position

open_B_T

openPT

[2]

 

Open (1) and closed (0) path P -> T as function of normalized spool position

open_P_T

openAB

[2]

 

Open (1) and closed (0) path A -> B as function of normalized spool position

open_A_B

[1] 1.,0.750,0.500,0.250,0.,0.250,0.500,0.750,1.

[2] 0.,0.,0.,0.,0.,0.,0.,0.,0.

Constant Parameters

Name

Default

Units

Description

Modelica ID

spooldata

[spool_x_axis; open_P_A; open_P_B; open_A_T; open_B_T; open_A_B; open_P_T]

 

 

spool_data

See Also

Adding Text and Illustrations to a Subsystem or Custom Component

DirectionalControl

Grouping Modeling Components into Subsystems

MapleSim Hydraulics Library from Modelon Overview

 


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