Valve Assembly For Fuel System And Method
AssigneeCaterpillar Inc.
InventorsBao Feng, Steven C. Taylor, Lucy V. Berg, Colm M. Flannery
Life of this patent
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Abstract
A valve assembly in an internal combustion engine fuel system includes a valve member movable within a valve body to contact a valve seat and block fluid communication between first and second passages. The valve seat and valve member each include a multi-layered coating having a harder metal nitride base layer and a softer metal nitride outer layer. The base layer is relatively incompliant to impacts between the valve member and the valve seat, and the outer layer is relatively compliant to the impacts and thereby deformable. Related methodology is disclosed.
Claims20
A valve assembly for a fuel system in an internal combustion engine comprising:
- a valve body having therein a valve seat located fluidly between a first fluid passage and a second fluid passage and being formed of a first metal substrate;
- a valve member movable within the valve body between a first position at which the valve member contacts the valve seat and blocks fluid communication between the first and second fluid passages, and a second position at which the fluid communication is open, and the valve member being formed of a second metal substrate;
- the valve seat and the valve member each including a multi-layer coating positioned within a sealing interface formed by the contact at the first position, and having a metal nitride base layer adherent to the corresponding first or second metal substrate, and a metal nitride outer layer;
- the metal nitride base layer having a greater hardness, such that the metal nitride base layer is relatively incompliant to impacts between the valve member and the valve seat at the first position and limits wear of the valve member and the valve seat during service of the valve assembly in the fuel system;
- and
- the metal nitride outer layer having a lesser hardness, such that the metal nitride outer layer is relatively compliant to the impacts and is thereby deformable to enlarge the sealing interface during break-in of the valve assembly in the fuel system.
A fuel system for an internal combustion engine comprising:
- a housing defining a first fuel passage and a second fuel passage, and having a valve seat formed of a first metal substrate and positioned fluidly between the first and second fuel passages;
- a valve assembly positioned at least partially within the housing and configured to control a flow of fuel between the first and second fuel passages, and including a valve member formed of a second metal substrate and movable between a first position at which the valve member contacts the valve seat and blocks fluid communication between the first and second fuel passages, and a second position at which the fluid communication is open;
- the valve seat and the valve member each including a multi-layer coating positioned within a sealing interface formed by the contact at the first position, and having a metal nitride base layer adherent to the corresponding first or second metal substrate, and a metal nitride outer layer;
- the metal nitride base layer having a greater hardness, such that the metal nitride base layer is relatively incompliant to impacts between the valve member and the valve seat at the first position and limits wear of the valve member and the valve seat during service of the valve assembly in the fuel system;
- and
- the metal nitride outer layer having a lesser hardness, such that the metal nitride outer layer is relatively compliant to the impacts and is thereby deformable to enlarge the sealing interface during break-in of the valve assembly in the fuel system.
A method of limiting valve damage during breaking-in a valve assembly in a fuel system of an internal combustion engine comprising the steps of:
- moving a valve member of the valve assembly from a first position at which a first fuel passage and a second fuel passage in the fuel system are in fluid communication via a valve seat, to a second position at which the valve member contacts the valve seat to block the fluid communication;
- transmitting a force of impact of the valve member on the valve seat at the second position from a softer outer layer of a metal nitride coating on at least one of the valve member and the valve seat to a harder base layer of the metal nitride coating adherent to a metal substrate of the at least one of the valve member and the valve seat;
- and
- preventing failure of the harder base layer in response to the transmission of the force via deforming the softer outer layer in response to the impact.
Dependencies are inferred from the claim text.