Pressure regulator for a liquid

1. A coaxial liquid pressure regulator, comprising:

a housing defining a longitudinal axis and having an inlet portion and an outlet portion;

a substantially tubular valve member slidingly accommodated inside the housing and having an upstream end with an inlet edge;

a valve body fixed inside the housing and having a valve seat configured to interact with the inlet edge of the valve member and form therewith a port having a variable width;

an elastic annular diaphragm adapted to connect the valve member to the housing to form a regulating chamber therewith;

wherein the valve member, at a downstream end, has an outlet edge, the outlet edge being configured to interact with the outlet portion and form therewith an annular passage in communication with the regulating chamber;

wherein a width of the annular passage is variable and decreases as the inlet edge of the valve member moves toward the seat to reduce a liquid flow toward the regulating chamber and avoid sudden pressure changes, vibrations and water hammers;

wherein the outlet edge of the valve member has a first outer annular projection having a first diameter, and the outlet portion of the housing has a second inner annular projection having a second diameter which is greater than the first diameter, the annular passage having a width given by a difference of inner and outer diameters and by a position of the first annular projection relative to the second annular projection;

wherein the valve member is movable between a maximum open position when the inlet edge of the valve member is at a maximum distance from the valve seat with respect to the liquid flow demanded by a downstream distributor and a minimum open position with the inlet edge of the valve member at a minimum distance from the valve seat with respect to the liquid flow demanded by the downstream distributor; and

wherein the annular passage has a maximum width with the inlet edge at the maximum distance and wherein the first annular projection and the second annular projection are fully axially offset to define a gap of approximately constant maximum width therebetween.

2. The coaxial liquid pressure regulator as claimed in claim 1 , further comprising, inside the inlet portion of the housing, a substantially tubular sleeve with an annular collar having a calibrated hole for axially guiding the valve member.

3. The coaxial liquid pressure regulator as claimed in claim 2 , wherein the valve member has a substantially radial flange adjacent to the outlet edge, a compression spring being interposed between the annular collar and the flange and peripherally surrounding the valve member to bias the valve member downstream.

4. The coaxial liquid pressure regulator as claimed in claim 3 , wherein the annular diaphragm has an inner peripheral portion clamped to the flange and an outer peripheral edge clamped to the housing to define the regulating chamber.

5. The coaxial liquid pressure regulator as claimed in claim 4 , wherein the outlet portion of the housing has a wider region with an annular transverse surface defining a bottom of the regulating chamber.

6. The coaxial liquid pressure regulator as claimed in claim 1 , wherein the inlet portion, the valve seat, the valve member and the outlet portion of the housing are coaxial with one another.

7. The coaxial liquid pressure regulator as claimed in claim 1 , wherein the inlet portion, the valve seat, the valve member and the outlet portion of the housing are angularly and/or transversely offset from one another.

8. A method of operating a liquid pressure regulator as claimed in claim 1 , the method comprising the following steps:

causing a liquid to enter the inlet portion of the housing;

causing the liquid to flow into the valve member after bypassing the valve body;

causing part of the liquid to flow back toward the regulating chamber due to a downstream back pressure generated by a nozzle or a liquid delivery device;

causing the valve member to be displaced as a counteracting force of a spring is exceeded and the inlet edge moves toward the valve seat to reduce a pressure of the liquid;

wherein the liquid flows back toward the regulating chamber through the annular passage of variable width; and

wherein the width decreases as the inlet edge of the valve member moves toward the valve seat to reduce the flow toward the regulating chamber and avoid sudden pressure changes, vibrations and water hammers.

9. A coaxial liquid pressure regulator, comprising:

a housing defining a longitudinal axis and having an inlet portion and an outlet portion;

a substantially tubular valve member slidingly accommodated inside the housing and having an upstream end with an inlet edge;

a valve body fixed inside the housing and having a valve seat configured to interact with the inlet edge of the valve member and form therewith a port having a variable width;

an elastic annular diaphragm adapted to connect the valve member to the housing to form a regulating chamber therewith;

wherein the valve member, at a downstream end, has an outlet edge, the outlet edge being configured to interact with the outlet portion and form therewith an annular passage in communication with the regulating chamber;

wherein a width of the annular passage is variable and decreases as the inlet edge of the valve member moves toward the seat to reduce a liquid flow toward the regulating chamber and avoid sudden pressure changes, vibrations and water hammers;

wherein the outlet edge of the valve member has a first outer annular projection having a first diameter, and the outlet portion of the housing has a second inner annular projection having a second diameter which is greater than the first diameter, the annular passage having a width given by a difference of inner and outer diameters and by a position of the first annular projection relative to the second annular projection;

wherein the valve member is movable between a maximum open position when the inlet edge of the valve member is at a maximum distance from the valve seat with respect to the liquid flow demanded by a downstream distributor and a minimum open position with the inlet edge of the valve member at a minimum distance from the valve seat with respect to the liquid flow demanded by the downstream distributor; and

wherein the annular passage has a minimum width with the inlet edge at the minimum distance and wherein the first annular projection and the second annular projection are in a fully overlapping position to define a gap of minimum width therebetween, adapted to reduce the liquid flow in the regulating chamber and to avoid an occurrence of the water hammers and the vibrations inside the regulating chamber.

10. A coaxial liquid pressure regulator, comprising:

a housing defining a longitudinal axis and having an inlet portion and an outlet portion;

a substantially tubular valve member slidingly accommodated inside the housing and having an upstream end with an inlet edge;

a valve body fixed inside the housing and having a valve seat configured to interact with the inlet edge of the valve member and form therewith a port having a variable width;

an elastic annular diaphragm adapted to connect the valve member to the housing to form a regulating chamber therewith;

wherein the valve member, at a downstream end, has an outlet edge, the outlet edge being configured to interact with the outlet portion of the liquid and form therewith an annular passage in communication with the regulating chamber;

wherein a width of the annular passage is variable and decreases as the inlet edge of the valve member moves toward the seat to reduce a liquid flow toward the regulating chamber and avoid sudden pressure changes, vibrations and water hammers;

further comprising, inside the inlet portion of the housing, a substantially tubular sleeve with an annular collar having a calibrated hole for axially guiding the valve member;

wherein the valve member has a substantially radial flange adjacent to the outlet edge of the liquid, a compression spring being interposed between the annular collar and the flange and peripherally surrounding the valve member to bias the valve member downstream;

wherein the outlet portion of the housing has a wider region with an annular transverse surface defining a bottom of the regulating chamber; and

wherein the annular transverse surface is inclined toward a center to facilitate conveyance and discharge of any sand and impurities collected in the regulating chamber to an outside at an end of an operation of the pressure regulator with the valve member biased by the compression spring to a maximum open position.

11. The coaxial liquid pressure regulator as claimed in claim 10 , wherein the annular diaphragm has an inner peripheral portion clamped to the flange and an outer peripheral edge clamped to the housing to define the regulating chamber.

12. The coaxial liquid pressure regulator as claimed in claim 10 , wherein the outlet edge of the valve member has a first outer annular projection having a first diameter, and the outlet portion of the housing has a second inner annular projection having a second diameter which is greater than the first diameter, the annular passage having a width given by a difference of inner and outer diameters and by a position of the first annular projection relative to the second annular projection.

13. The coaxial liquid pressure regulator as claimed in claim 12 , wherein the valve member is movable between a maximum open position when the inlet edge of the valve member is at a maximum distance from the valve seat with respect to the liquid flow demanded by a downstream distributor and a minimum open position with the inlet edge of the valve member at a minimum distance from the valve seat with respect to the liquid flow demanded by the downstream distributor.

14. The coaxial liquid pressure regulator as claimed in claim 13 , wherein the annular passage has a maximum width with the inlet edge at the maximum distance and wherein the first annular projection and the second annular projection are fully axially offset to define a gap of approximately constant maximum width therebetween.