Apparatus and methods for regulating negative pressure in a negative pressure wound therapy system

A pressure switch for controlling application of negative pressure to dressing disposed adjacent a tissue site, comprising:

• a body having a base, sidewalls extending from the base to an open end, and an inlet coupled to the dressing and forming a passage through the body;
• a diaphragm closing the open end of the sidewalls and forming a vacuum chamber with the body, wherein the inlet fluidly couples the vacuum chamber and the dressing;
• a valve disposed in the passage and configured to restrict the flow of gas through the passage so that a switch pressure developed in the vacuum chamber as a result of the application of negative pressure to the dressing lags a wound pressure at the tissue site, wherein the diaphragm is adapted to be operatively responsive to the switch pressure to move between a relaxed position and a compressed position as the negative pressure increases and decreases;
• and
• a switching element coupled to the diaphragm to turn on the negative pressure in the relaxed position and turn off the negative pressure in the compressed position.

A method for controlling application of negative pressure to dressing disposed adjacent a tissue site, comprising:

• positioning a dressing including a tissue interface for distributing negative pressure to the tissue site in contact with the tissue site;
• coupling a pressure switch to the dressing, the pressure switch having a vacuum chamber and an inlet valve configured to restrict the flow of gas into the vacuum chamber when negative pressure is provided to the tissue interface to develop a switch pressure in the vacuum chamber, wherein the pressure switch operatively responds to the switch pressure to move between a relaxed position and a compressed position as the negative pressure increases and decreases;
• providing negative pressure to the tissue interface to generate a wound pressure at the tissue site;
• receiving the negative pressure from the dressing into the vacuum chamber of the pressure switch wherein the switch pressure lags the wound pressure;
• and
• turning on the negative pressure when the pressure switch is in the relaxed position and turning off the negative pressure when the pressure switch is in the compressed position.