Spool with a Preload

Introduction

To avoid chattering when using a spool in a hydraulic valve, it is often necessary to hold the spool in a locked position until the external force exceeds a certain threshold value. In this example of a spool with a preload, we will explore the interaction between such a force and the spool's position.

In order to get the full experience of this example, you need the following:

• A desktop Wolfram Language product; a free trial download is available at www.wolfram.com/mathematica/trial/
• The SpoolWithAPreLoad.nb notebook that came in the same bundle as this model

System Architecture

The system is a standard example in the Modelica.Mechanics.Translation library showing an example of usage of the ElastoGap component (the outer and inner contacts in the model). The ElastoGap component is essentially a spring-damper component with a gap, meaning that the spring damper will only be used if the gap is closed. This behavior simulates the desired preload to the spool.

A force is generated from a source and applied to the spool. When the spool has moved a threshold distance, which has the effect of loading a force in a spring, the gap is closed in the Contact components and the spool will begin to move.

Above is a diagram view of the model.

Further Investigation

In the accompanying notebook, the behavior of this system is animated and can be interacted with.

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