Patent ID: 7712685

Claim:
A device for fuel injection rate shaping, the device having first and second ends and comprising: a body defining an interior space, a first channel at the first end of the device for fuel primarily entering the device and a second channel at the second end of the device for fuel primarily leaving the device, the first and second channels being in communication with the interior space of the body, and a first piston movably disposed in the interior space of the body and dividing the interior space into a first main chamber and a second main chamber having respective volumes that depend upon the position of the first piston, whereby fuel entering the device through the first channel enters the first main chamber, the first piston having an outer wall defining a recess and also having a middle section formed with a passage, and the recess of the first piston being open toward the first end of the device, a first resilient means located in the second chamber to bias the first piston toward the first end of the device, a channel construction arranged so that one end thereof is supported by the second end of the device and another end is located in the passage of the first piston, whereby the first piston is slidable with respect to the channel construction, a second piston located in the recess of the first piston and slidable with respect to the first piston, the second piston being formed with a passage, and a second resilient means to bias the second piston toward said channel construction, and wherein the device defines at least one auxiliary chamber, initial movement of the first piston in a first direction unites the auxiliary chamber with the first main chamber, whereby the auxiliary chamber is filled with fuel from the first main chamber, subsequent movement of the first piston in a second direction, opposite said first direction, results in increase in pressure in the auxiliary chamber, and further movement of the first piston in the second direction establishes a connection between the auxiliary chamber and the second main chamber, permitting fuel flow from the auxiliary chamber to the second main chamber and speeding up movement of the piston in the second direction.