Regulator
A low pressure regulator for a high pressure fuel pump includes a standard damping orifice, providing a constant level of piston movement damping by enabling a fluid pathway between a spring chamber and a return line. The low pressure regulator also includes a further damping orifice, which is covered by the piston when discharge port holes are open, the further damping orifice providing a further, variable level of piston movement damping by providing a further fluid pathway between the spring chamber and return line. The further damping orifice is open in a hydraulic accumulator mode and closed in a regulator mode, thereby reducing pressure spikes caused by insufficient spring chamber filling.
1. A low pressure regulator comprising:
a body;
a spring located within a spring chamber formed in an interior of the body;
a piston located between the spring chamber and a first end of the low pressure regulator;
at least one discharge port hole, and a first damping orifice which provides a constant fluid pathway between the spring chamber and a return line, such that the first damping orifice and the spring chamber provide a first, constant level of damping of movement of the piston; and
at least one further damping orifice, which communicates with the interior of the low pressure regulator and with the return line;
wherein the piston is movable within the interior of the body between a closed position and a fully open position;
wherein when the piston is in the closed position, each discharge port hole is blocked by an outer wall of the piston, and when the piston is in the fully open position, a first fluid pathway is enabled between the interior of the low pressure regulator and the return line through each discharge port hole; and
wherein when the piston is in the closed position, the at least one further damping orifice provides a second fluid pathway between the spring chamber and the return line, and when the piston is in the fully open position, the at least one further damping orifice is blocked by the outer wall of the piston; such that the at least one further damping orifice and the spring chamber provide a second, variable level of damping of movement of the piston.
2. A low pressure regulator as claimed in claim 1 wherein when the piston is at a certain position between the closed position and the fully open position, each discharge port hole, and each further damping orifice, are blocked by the outer wall of the piston.
3. A low pressure regulator as claimed in claim 1 wherein when the piston is at a certain position between the closed positon and the fully open position, each discharge port hole is blocked by the outer wall of the piston, and each further damping orifice is partially blocked by the outer wall of the piston.
4. A low pressure regulator as claimed in claim 1 wherein when the piston is at a certain position between the closed positon and the fully open position, each discharge port hole is not blocked by the outer wall of the piston, and each further damping orifice is not blocked by the outer wall of the piston.