Multiposition Valve Actuator

Multiposition actuator in any fluid domain

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Libraries:
Simscape / Fluids / Valve Actuators
Simscape / Fluids / Isothermal Liquid / Valves & Orifices / Valve Actuators & Forces / Valve Actuators

Description

The Multiposition Valve Actuator block models a multiposition actuator in any fluid domain. You can use it in combination with any valve block that takes a physical signal as input. The input signal and the switching time affect the actuator position.

Two-Position Actuator Movement

Actuation begins when the value of the signal at port A exceeds 50% of the value of the Nominal signal value parameter. After a time period that equals one third of the value of the Switching-on time parameter, the actuator begins to move toward the limit specified by the Push-pin stroke parameter.

When the value of the signal at port A falls below 50% of the value of the Nominal signal value parameter, the actuator reverses its direction after a time period that equals one third of the value of the Switching-off time parameter. The motion can be interrupted mid-stroke.

In the image above, t_on is the value of the Switching-on time parameter. The actuator motion during t_on contains an initial rest, a quadratic motion, and a linear motion, represented by t_de, t_ae, and t_ve, respectively. t_de, t_ae, and t_ve are all equal length.

The actuator switches direction when the control signal is off. t_off is the value of the Switching-off time parameter, during which the actuator repeats the same stages as the switching-on motion. t_dr is a stage of rest, t_ar is a stage of quadratic motion, and t_vr is a stage of linear motion. At the end of t_off, the actuator position is at the value of the Initial position parameter. t_dr, t_ar, and t_vr are all equal length.

When Actuator positions is 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.

Examples

2-Position Valve Actuator

Demonstrates the Multiposition Valve Actuator block with two positions. The same signal controls two valve actuators, but the actuators use different values of the Switching-on time, Switching-off time, and Initial position parameters.

• Open Model

3-Position Valve Actuator

The behavior of three different Multiposition Valve Actuator blocks. In each block Actuator positions is 3. All three actuators are driven by the same pulse signals. The values of the Push-pin stroke, Switching-on time and Switching-off time parameters of the three actuators are different, which illustrates the parameter impact.

• Open Model

Sequencing Circuit for Two Rotary Actuators

A sequencing circuit that is based on four check valves installed in the pressure and return lines of the second rotary actuator. The cracking pressure of the meter-in check valves is set high enough to prevent flow into rotary actuator 2 while rotary actuator 1 is rotating, but lower than the pressure that develops once rotary actuator 1 reaches its hard stop. As a result, rotary actuator 2 starts moving only after rotary actuator 1 completes its stroke.

• Open Model

Ports

Input

A — Input signal

physical signal

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 travel direction setting.

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

B — Input signal

physical signal

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

Dependencies

To enable this port, set Actuator positions to 3.

Output

S — Actuator position, m

physical signal

Actuator position, in m, specified as a physical signal.

If you use the Multiposition Valve Actuator block with a valve from the Gas Library, the gas block converts the actuator signal units of m to units of 1.

Parameters

Actuator positions — Number of valve position signals

2 (default) | 3

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.

Push-pin stroke — Maximum push-pin extension

0.01 m (default) | positive scalar

Maximum push-pin extension.

Switching-on time — Signal transition time period

0.1 s (default) | positive scalar

Time period to reach the value of the Push-pin stroke parameter. The period begins after the input signal rises above 50% of the value of the Nominal signal value parameter.

Switching-off time — Signal transition time period

0.1 s (default) | positive scalar

Time period to return to the Initial position parameter from the Push-pin stroke parameter. The period begins after the input signal falls below 50% of the Nominal signal value.

Nominal signal value — Nominal signal for fully extended actuator

24 (default) | positive scalar

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

Initial position — Actuator starting position

Retracted (default) | Extended | Neutral

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.

Actuator travel direction — Direction of actuator motion

Positive (default) | Negative

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™.

Version History

Introduced in R2020a