Differential pressure switch assembly with high static pressure use characteristics

In a differential pressure switch having a pressure cavity in which is mounted a flexible diaphragm separating high and low pressure chambers, and in which motion of the diaphragm due to increases in the differential between fluid pressures in the respective chambers is to actuate a snap action switch mechanism located exteriorly of the chambers, said switch comprising:

• a first rigid member defining the high pressure chamber and means for connecting a high pressure fluid source thereto,
• a second rigid member fixedly mounting a diaphragm plate defining a recess opposing the high pressure chamber,
• with the high pressure chamber and said recess being in congruent relation and having congruent marginal walls that are seated against the diaphragm,
• and with the high pressure chamber and said recess being centered on a first axis that extends normally of said diaphragm,
• a piston mounted in said second rigid member in substantially centered relation with said axis and having one end of same engaging the diaphragm through said diaphragm plate,
• a range spring seated on the other end of said piston for adjustably biasing said piston for movement along said axis toward the high pressure chamber,
• said piston being guided for movement longitudinally of said axis,
• a third rigid member anchored to said second rigid member defining a subchamber in which said range spring is received,
• said second rigid member being recessed about said piston to define a void space thereabout,
• said second rigid member and said third member recessing defining a composite low pressure chamber,
• said second rigid member having means for connecting the source of low pressure to same and said composite low pressure chamber,
• a rock shaft journaled in said second rigid member for rocking movement about a rocking axis that lies in a plane that is normally oriented relative to said first axis and said piston,
• said rock shaft having a first radial arm coupled to said piston for movement therewith and exposed to said composite low pressure chamber,
• said rock shaft having a second radial arm spaced longitudinally of said shaft from said first radial arm,
• means for sealing said second radial arm from said low pressure composite chamber,
• and mechanical means interposed between said second radial arm and the snap action switch mechanism for actuating the switch mechanism when the differential pressure of said chambers reaches a predetermined amount.

In a differential pressure switch assembly having an internal pressure cavity across which is mounted a flexible diaphragm separating high and low pressure chambers, and having a snap action switch mechanism mounted externally of the pressure cavity in which motion of the diaphragm due to increases in the differential between fluid pressures in the respective chambers is to actuate the snap action switch mechanism, said switch assembly comprising:

• a composite body defining the switch pressure cavity,
• with the snap action switch mechanism being mounted externally of said body,
• said body comprising:
• a first rigid member defining the high pressure chamber and means for connecting a high pressure fluid source thereto,
• a second rigid member defining a segment of the low pressure chamber and anchored to said first member,
• with the high pressure chamber and the low pressure chamber segment being in congruent relation and separated only by the diaphragm and having congruent marginal walls that are seated against the diaphragm,
• with the high pressure chamber and the low pressure chamber segment being centered on a first axis that extends normally of said diaphragm,
• and with the diaphragm being sandwiched between said first and second rigid members,
• a piston mounted in said second rigid member in substantially centered relation with said axis and having opposed ends, one of which engages the diaphragm,
• a range spring seated on the other end of said piston for adjustably biasing said piston for movement along said axis toward the high pressure chamber and into engagement with said diaphragm,
• said piston being guided for movement longitudinally of said axis,
• a third rigid member anchored to said second rigid member and being substantially centered on said axis,
• said third rigid member defining a recess to receive said range spring therein, in which recess said range spring is received,
• said second rigid member being recessed about said piston to define a void space thereabout intermediate said ends thereof,
• said second rigid member and said third member recessing defining together with said low pressure chamber segment a composite low pressure chamber within said body,
• said second rigid member having means for connecting the source of low pressure to same and said composite low pressure chamber,
• a rock shaft journaled in said second rigid member for rocking movement about a rocking axis that is spaced to one side of said first axis and is in a plane that is oriented relative to said first axis and said piston to be substantially normally thereof,
• said rock shaft having a first radial arm coupled to said piston for movement therewith and exposed to said composite low pressure chamber,
• said rock shaft having a second radial arm spaced longitudinally of said shaft from said first radial arm,
• means for sealing said second radial arm from said low pressure composite chamber,
• means for sealing said third member recess against fluid under pressure in said composite chamber,
• and mechanical means interposed between said second radial arm and the snap action switch mechanism for actuating the switch mechanism when the differential pressure of said chambers reaches a predetermined amount.

In a differential pressure switch having a pressure cavity in which is mounted a flexible diaphragm separating high and low pressure chambers, and in which motion of the diaphragm due to increases in the differential between fluid pressure in the respective chambers is to actuate a switch mechanism located exteriorly of the chamber, said switch comprising;

• a first body segment defining the high pressure chamber and means for connecting a high pressure fluid source thereto,
• second body segment formed to define a recess opposing the high pressure chamber,
• with the high pressure chamber and said recess being in congruent relation and having congruent marginal walls that are seated against the diaphragm,
• and with the high pressure chamber and said recess being centered on a first axis that extends normally of said diaphragm,
• a piston mounted in said second body segment and extending through said recess in substantially centered relation with said axis and having one end of same engaging the diaphragm,
• a range spring seated on the other end of said piston for adjustably biasing said piston for movement along said axis toward the high pressure chamber,
• said piston being guided for movement longitudinally of said axis,
• means for defining a subchamber in which said range spring is received,
• said second body segment being recessed about said piston to define a void space thereabout,
• said second body segment and said defining means together defining a composite low pressure chamber,
• said second body segment having means for connecting the source of low pressure to same and said composite low pressure chamber,
• a rock shaft journaled in said second body segment for rocking movement about a rocking axis that lies in a plane that is normally oriented relative to said first axis and said piston,
• said rock shaft having a first radial arm coupled to said piston for movement therewith and exposed to said composite low pressure chamber,
• said rock shaft having a second radial arm spaced longitudinally of said shaft from said first radial arm,
• means for sealing said second radial arm from said low pressure composite chamber,
• and mechanical means interposed between said second radial arm and the switch mechanism for actuating the switch mechanism when the differential pressure of said chambers reaches a predetermined amount.