| 摘要 |
<p>The invention relates to a method for regulating a fluid flow in a conduit such as a combustion air i.e. draught of central heating boilers in a flue or maintaining constant pressure in a space to which the conduit is connected. A valve (50) placed in the conduit is controlled by means of appropriate physical characteristics such as pressure and/or temperature of fluid. There is connected between the said conduit and the environment of the boiler or another appropriate space a control conduit and the control flow in the said control flow conduit is regulated by means of the known method based on the principle of cascade flow in which method there is arranged in connection with the conduit preferably a cylinder space having the end walls one of which being movable and which cylinder space is connected with the first opening (d min 1) against the comparison or inlet pressure (p1) and the second opening (d min 2) against the outlet pressure (p3) or the pressure in the conduit and in which method the regulation of the internal pressure (p2) of the cylinder space is effected through changing the mutual ratio of the areas of the openings (d min 1, d min 2) by a piston (14, 19) joined to the movable wall and or through controlling the mutual ratio of the areas of the openings from outside of the cylinder space so that the piston force needed for changing the cross-sectional flow area of the opening and needed for the regulation of flow at each moment and each pressure difference is equal to the sum of the forces opposing the said movement and the displacement of the movable wall and the piston at the same time is transmitted further to the control movement of the position of the valve's flap (51).</p> |
