Patent ID: 8613126

Claim:
A door closure for providing a closing boost comprising: an elongated housing mounted to a door, the housing having first and second opposite ends and being divided generally into first, second and third fluid chambers: a first piston movably mounted in the housing to move fluid between the first and third fluid chambers, the first piston including a rack engaging a pinion to move the first piston is response to the door opening and to enable the door to close; a piston rod and retainer connected to the first piston and movable therewith; a second, cup shaped piston movably mounted in the housing and forming the second fluid chamber; a first spring mounted in the first fluid chamber of the housing and operatively connected to the first piston; a second spring mounted in the third fluid chamber of the housing operatively connected to the second piston; a first fluid passageway between the first fluid chamber and the third fluid chamber; a second fluid passageway between the first fluid chamber and the second fluid chamber and including a check valve; a third fluid passageway between the first and third fluid chambers; and a fourth fluid passageway between the first and second fluid chambers; and wherein upon the door opening, fluid is transferred from the first fluid chamber to the third fluid chamber through the first fluid passageway, and initially through the third fluid passageway, and the first spring is compressed, and concluding with fluid selectively transferring through the second fluid passageway from the first fluid chamber to the second fluid chamber to move the second piston and compress the second spring; and upon the door closing, the first spring extends against the first piston, fluid is transferred from the third fluid chamber to the first fluid chamber through the first fluid passageway and the third fluid passageway, and fluid is selectively transferred from the second fluid chamber to the first fluid chamber through the fourth fluid passageway to boost closing of the door.