US-12618387-B2 - Valve assembly for a fuel pump

US12618387B2US 12618387 B2US12618387 B2US 12618387B2US-12618387-B2

Abstract

A valve assembly for a fuel pump for a fuel system, the fuel pump comprising a pump chamber and the valve assembly comprising a solenoid winding; and an electromagnetically controlled armature operable under the influence of an electromagnetic field generated by applying a current to the solenoid winding. The armature is coupled to a valve member cooperable with a valve seat to control fuel flow, and the armature is movable within an armature bore and is exposed to fuel within an armature chamber defined within the armature bore. The valve assembly includes a clearance defined between the armature and the armature bore which defines a variable restriction to the fuel flow, whereby during armature movement in use the fuel is displaced from the armature chamber through the variable restriction so that the speed of movement of the armature is reduced as the armature moves further into the armature chamber.

Inventors

Erol Kahraman
Kevin Laity

Assignees

PHINIA DELPHI LUXEMBOURG SARL

Dates

Publication Date: 20260505
Application Date: 20220609
Priority Date: 20210609

Claims (8)

1 . A valve assembly for a fuel pump for a fuel system, the fuel pump comprising a pump chamber, and the valve assembly comprising: a solenoid winding; an electromagnetically controlled armature operable under the influence of an electromagnetic field generated by applying a current to the solenoid winding, the armature being shaped to have an outer surface of variable diameter including a tapered region, and the armature being coupled to a valve member which is cooperable with a valve seat to control fuel flow into and out of the pump chamber, an armature chamber defined within an armature bore; and an armature lift stop defined within the armature chamber; wherein: the armature is movable within the armature bore towards and away from the armature lift stop and is exposed to fuel within the armature chamber, the armature lift stop serves to limit the extent of movement of the armature into the armature chamber, the tapered region of the armature and the armature bore defining a variable clearance flow path out of the armature chamber which varies through the range of travel of the armature within the armature chamber so as to define a variable restriction to the fuel flow out of the armature chamber, and the variable clearance flow path reduces in size as the armature moves towards the armature lift stop, whereby during armature movement in use the fuel is displaced from the armature chamber through the variable clearance flow path so that the speed of movement of the armature is reduced as the armature moves further into the armature chamber towards the armature lift stop.
2 . The valve assembly as claimed in claim 1 , wherein the tapered region reduces the diameter of the armature from a smaller diameter at one end of the armature to a larger diameter in a central region of the armature.
3 . The valve assembly as claimed in claim 2 , including a tapered region on each side of the central region so that the upper and lower ends of the armature are of reduced diameter compared to the central region.
4 . The valve assembly as claimed in claim 3 , wherein the outer surface of the armature includes a central region of enlarged diameter.
5 . The valve assembly as claimed in claim 4 , wherein the outer surface of the armature is of reduced diameter on both upper and lower sides of the central region.
6 . The valve assembly as claimed in claim 1 , wherein the armature has an outer surface of constant diameter and wherein the armature bore is shaped to have a variable internal diameter.
7 . The valve assembly as claimed in claim 1 , wherein the armature bore is shaped to have a variable internal diameter.
8 . A fuel pump comprising a valve assembly as claimed in claim 1 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. National Stage of International Application No. PCT/EP2022/065680 filed on 9 Jun. 2022, which claims priority to and all advantages of United Kingdom Application No. 2108232.6 filed on 9 Jun. 2021, the contents of which are incorporated herein by reference. FIELD OF THE INVENTION This invention relates to a valve assembly for a fuel pump. In particular, but not exclusively, the invention relates to a valve assembly for use in a fuel pump of a compression ignition internal combustion engine. BACKGROUND In an internal combustion engine, fuel to a common rail fuel volume where the fuel is stored at high pressure prior to delivery to the fuel injectors of the engine. The common rail fuel pump typically includes at least one pumping plunger which is driven by means of a cam to perform a pumping cycle during which fuel is pressurised within a pump chamber associated with the plunger for delivery to the common rail. The plungers may be configured in many different layouts, from in-line arrangements to radial. It is common for the pump assembly to include multiple plungers to provide an increased pump capacity. Each plunger typically has an associated valve assembly which is operable to control when in the pump cycle fuel is pressurised within the pump chamber and when fuel is drawn into the pump chamber for pressurisation. Electromagnetically controlled valves are commonly used for this purpose. Such valves include an electromagnetic actuator including a solenoid winding to which a current is supplied to create an electromagnetic field which acts on an armature coupled to a valve member. The valve member is movable towards a valve seat as the solenoid winding is energised, as the electromagnetic field acts on the armature which carries the valve member with it. Typically, the actuator may be the ‘energise-to-close’ type in which actuation of the solenoid winding causes the valve member to be drawn towards the valve seat, in which position fuel within the pump chamber is pressurised as the plunger is driven. The valve is caused to move away from the valve seat under the influence of a valve spring which acts against the actuation force of the actuator. The assembly is provided with a lift stop for the armature to limit the extent of movement of the armature (and hence the valve member) in the opening direction. One problem which occurs in such an arrangement is that the valve member and the armature are moving at considerable speed when opening and the armature impacting the lift stop can cause damage to the armature and noise within the assembly. It is difficult to avoid this because the armature is made from a relatively soft, electromagnetic material so as to perform its function, but the material is easily damaged. It is against this background that the invention has been devised. STATEMENTS OF INVENTION According to the present invention, there is provided a valve assembly for a fuel pump for a fuel system, the fuel pump comprising a pump chamber and the valve assembly comprising a solenoid winding and an electromagnetically controlled armature operable under the influence of an electromagnetic field generated by applying a current to the solenoid winding. The armature is coupled to a valve member which is cooperable with a valve seat to control fuel flow into and out of the pump chamber. The armature is movable within an armature bore and is exposed to fuel within an armature chamber defined within the armature bore, the valve assembly including a clearance defined between the armature and the armature bore which defines a variable restriction to the fuel flow, whereby during armature movement in use fuel is displaced from the armature chamber through the variable restriction so that the speed of movement of the armature is reduced as the armature moves further into the armature chamber. The armature may be shaped to have an outer surface of variable diameter which defines the clearance, together with the armature bore. For example, the outer surface of the armature may include a tapered region. In one embodiment, the tapered region reduces the diameter of the armature from a smaller diameter at one end of the armature to a larger diameter in a central region of the armature. A tapered region may be included on each side of the central region so that the upper and lower ends of the armature are of reduced diameter compared to the central region. In another embodiment, the outer surface of the armature may include a stepped diameter. The outer surface of the armature may, for example, include a central region of enlarged diameter. The outer surface of the armature may be of reduced diameter on both upper and lower sides of the central region. The armature bore may be shaped to have a variable internal diameter. In other embodiments, the armature may have an outer surface of constant diameter, in which case the armature bore is shaped to have