| 摘要 |
<p>A piston for a linear spool valve, the valve comprising a body having a inner surface. The body is made of a material with a relatively low heat expansion coefficientα1. The piston comprises a contact member having an outer surface and being adapted to reciprocate within the body of the valve so that the outer surface is in contact with the inner surface. The contact member has at least a first layer made of a material with a heat expansion coefficientα2 essentially greater thanα1, i.e.α2>>α1, and at least a second layer made of a material with a heat expansion coefficientα3 close toα1. This causes the contact member to be adapted to behave, along said outer surface, as a material having a heat expansion coefficient essentially closer toα1 than toα2. One of the layers constitutes an outer layer of the contact member and comprises the outer surface.</p> |
