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Multiposition Valve Actuator

Multiposition actuator in an isothermal liquid system

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  • Multiposition Valve Actuator block

Description

The Multiposition Valve Actuator block models a multiposition actuator in an isothermal liquid system. It can be used in combination with the 2-Way Directional Valve (IL), 3-Way Directional Valve (IL), or 4-Way Directional Valve (IL) blocks. The actuator position is influenced by the input signal and switching time, and not by loading.

Two-Position Actuator Movement

Actuation begins when the signal at port A exceeds 50% of the Nominal signal value. After the time period set by the Switching-on time parameter, the actuator begins to move toward the Push-pin stroke limit. When the input signal at port A falls below 50% of the Nominal signal value, the actuator reverses its direction after the time period set by the Switching-off time parameter. The motion can be interrupted mid-stroke.

Actuator position

In the image above, tde is the Switching-on time, which is equal to the time periods tae and tve. In region tae, the actuator moves at constant acceleration with parabolic displacement. In region tve, the actuator moves linearly, with constant velocity, toward full push-pin extension. The actuator switches direction when the control signal is off:

  1. tdr is a transitional no-displacement time period set by the Switching-off time.

  2. tar is a period of acceleration with parabolic displacement.

  3. tvr is period of linear displacement toward the actuator Initial position.

When Actuator positions is set to 2, the Actuator travel direction parameter sets the direction of the push-pin motion.

The actuator motion can be interrupted at any time. If the push-pin motion is disrupted mid-stroke, the switch-on and switch-off times are adjusted proportionally to the push-pin position, relative to the push-pin stroke.

Three-Position Actuator Movement

When Actuator positions is set to 3, the signal at port A moves the actuator in a positive direction and the signal received at port B moves the actuator in a negative direction. Only one signal, from one port, is processed at a time. To switch control between ports A and B, or between positive and negative displacement control, the actuator must first move to a neutral position. If the push-pin motion is disrupted mid-stroke, the switch-on and switch-off times are adjusted proportionally to the push-pin position, relative to the push-pin stroke. The actuator motion can be interrupted at any time.

When controlled by the signal at port A, the three-position actuator has the same displacement profile as the two-position actuator when Actuator travel direction is set to Positive. When controlled by the signal at port B, it has the same profile as the two-position actuator when Actuator travel direction is set to Negative.

Ports

Input

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Input port, specified as a physical signal.

When Actuator positions is set to 2, this port can either control negative or positive actuator movement, according to the Actuator orientation setting.

When Actuator positions is set to 3, this port receives a physical signal that corresponds to a positive actuator displacement direction.

Input port for negative actuator displacement, received as a physical signal.

Dependencies

To enable this port, set Actuator positions to 3.

Output

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Actuator position in m, specified as a physical signal.

Parameters

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Number of valve position signals. When set to 2, the actuator receives one signal and sets one position signal. When set to 3, the actuator receives a positive and a negative signal and sets one position signal.

Maximum push-pin extension.

Transitional time period before the actuator begins to move. The period begins after the input signal rises above 50% of the Nominal signal value.

Transitional time period before the actuator reverses motion. The period begins after the input signal falls below 50% of the Nominal signal value.

Nominal signal for fully extended actuator. The actuator motion is triggered when the input signal reaches 50% of the Nominal signal value.

Starting position of the actuator. Retracted and Extended correspond to the actuator push-pin stroke limits.

When Actuator positions is set to 2, the Initial position default is Retracted. When Actuator positions is set to 3, the Initial position default is Neutral. Neutral corresponds to the middle of the Push-pin stroke.

Direction of the actuator motion in response to the physical signal input. The Positive setting corresponds to push-pin extension.

Dependencies

To enable this parameter, set Actuator positions to 2.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Introduced in R2020a