Quantity-limiting valve
In a quantity limiting valve for a fuel injection system of an internal combustion engine including a cylinder with an inflow region and an outflow region separated by a piston axially movably disposed in the cylinder and a flow limiting fluid flow path extending along the piston between the inflow and outflow regions wherein the piston is biased with its front surface into contact with a stop element, the contact area between the front surface and the stop surface includes between the piston and the stop element a contact structure providing for an intermediate space which is in communication with the inflow region thereby to expose the front surface of the piston to the pressure of the fluid in the inflow region.
1. A quantity limiting valve ( 1 ) for a fuel injection systems ( 6 ) of an internal combustion engine ( 8 ), the quantity limiting valve ( 1 ) including a cylinder ( 11 ) with an inflow region ( 7 ) and an outflow region ( 9 ) separated by a piston ( 13 ) which is movably guided in the cylinder ( 11 ), a fluid flow communication path ( 17 ) extending along the piston ( 13 ) between the inflow region ( 7 ) and an outflow region ( 9 ), the piston ( 13 ) having a front surface ( 25 ) and being biased toward a stop element ( 29 ) with a stop surface ( 27 ) holding the piston ( 13 ) in a first operating position thereof in contact with the stop surface ( 27 ), the contact area between the front surface ( 25 ) and the stop surface ( 27 ) being provided with a contact structure ( 39 ) which includes at least one intermediate space ( 41 ) which is disposed between the piston ( 13 ) and the stop element ( 29 ) and forming a gap in fluid communication with the inflow region ( 7 ) to permit the fluid to enter the intermediate space ( 41 ) between the piston ( 13 ) and the stop element ( 29 ) for rapid actuation of the piston ( 13 ).
2. The quantity limiting valve ( 1 ) according to claim 1 , wherein the contact structure ( 39 ) includes at least one projection ( 43 ) which extends toward the stop surface ( 27 ) and on which at least part of the front surface ( 25 ) is formed and also a cavity ( 44 ) extending into the front surface ( 25 ).
3. The quantity limiting valve ( 1 ) according to claim 1 , wherein the contact structure ( 39 ) has at least one projection extending from the stop element ( 29 ) toward the front surface ( 25 ) of the piston ( 13 ) and which forms at least part of the stop surface and at least one cavity ( 44 , 56 ) extending into the stop surface ( 27 ).
4. The quantity limiting valve ( 1 ) according to claim 1 , wherein the stop element ( 29 ) is in the form of a stop sleeve ( 48 ) extending onto the cylinder ( 11 ) and being provided with a collar ( 49 ) extending around the outer circumference of the stop sleeve ( 48 ) and being supported on a wall section ( 51 ) of the cylinder ( 11 ).
5. The quantity limiting valve ( 1 ) according to claim 1 , wherein the piston ( 13 ) is provided with at least one projection ( 59 ) which extends toward the stop element ( 29 ) and which is provided with the front surface ( 25 ) and forms at least one cavity ( 56 ) extending into the front surface ( 25 ).
6. The quantity limiting valve ( 1 ) according to claim 4 , wherein the stop sleeve ( 48 ) is provided with at least one projection ( 43 ) which extends toward the front surface of the piston ( 13 ) and which is provided with the stop surface ( 27 ) and with at least one cavity extending into the stop surface ( 27 ).
7. The quantity limiting valve ( 1 ) according to claim 3 , wherein the at least one cavity ( 44 , 56 ) is in the form of a radially extending groove ( 57 ).
8. The quantity limiting valve ( 1 ) according to claim 4 , wherein the stop sleeve ( 48 ) is provided with a through-bore ( 45 ) which at least to some extent forms the inflow region ( 7 ).
9. The quantity limiting valve ( 1 ) according to claim 7 , wherein the radially extending groove ( 57 ) is in fluid communication with the inflow region ( 7 ) and with the flow path ( 17 ) formed between circumferential surface area ( 19 ) of the piston ( 13 ) and the inner surface area ( 21 ) of the cylinder ( 11 ).