Patent Application
20110180635
The invention relates to fuel injectors for vehicles and, more particularly, to a high pressure fuel injector seat that resists distortion during welding when assembled.
With reference to
The valve seat 14 is a machined and ground part and is fixed to the valve body 12 via the hermitic weld 16 through the valve body wall and into the valve seat 14. During this operation, the material that was molten during the weld process shrinks during cooling causing distortion of the seat 14.
The distortion imposed on the critical areas of the seat 14 can be modeled through a displacement in the weld area. In a simulation, a four micron uniform displacement in the weld area was shown to result in an equivalent or greater displacement in the guide and seal area of the seat 14. It is noted that distortion by welding is not uniform and the resulting distortion of the seat 14 is thus also not uniform. This distortion of the seat 14 results in leaks at the seal and non-uniform shrinkage of the guide portion of the seat 14, which cause durability problems of the fuel injector 10.
Thus, there is a need to provide an improved fuel injector seat that resists distortion during welding upon assembly.
An object of the present invention is to fulfill the need referred to above. In accordance with the principles of an embodiment, this objective is obtained by providing a valve seat for a fuel injector that includes a main body having a proximal and a distal end with at least one orifice extending through the main body. A seating surface is provided on the main body to receive a closure member of a fuel injector such that when the closure member engages the seating surface, the at least one orifice is closed. A guide surface is provided on the main body to guide movement of the closure member. An annular wall extends in a cantilever manner from the main body at the distal end thereof and defines an outer peripheral portion of the valve seat. The wall is constructed and arranged to deform during welding at the wall so as to isolate effects of the welding from the seating surface and the guide surface.
In accordance with another aspect of the invention a method is provided to isolate a seating surface and a guide surface of a valve seat of a fuel injector during a welding process. A valve seat includes a main body having a proximal and a distal end, at least one orifice extending through the main body, a seating surface on the main body constructed and arranged to receive a closure member of a fuel injector such that when the closure member engages the seating surface, the at least one orifice is closed, a guide surface on the main body constructed and arranged to guide movement of the closure member, and an annular wall extending in a cantilever manner from the main body at the distal end thereof and defining an outer peripheral portion of the valve seat. The method includes welding the valve seat to a valve body of a fuel injector so that the annular wall deforms during welding thereby to isolating effects of the welding from the seating surface and the guide surface.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:
Referring to
The valve seat 16′ defines a seating surface 22, which can have a frustoconical or concave shape, facing the interior of the valve body 12. The seating surface 22 includes at least one fuel outlet opening 24 through a proximal end 25 of a main body 27 of the seat 16′. The opening 24 is in communication with an inlet tube 29 for conducting pressurized fuel into the valve body 12 against the seating surface 22. The inlet tube 29 defines an inlet end 31 (see
A closure member, e.g., a spherical valve ball 20, within the injector 10′ is moveable between a first, seated or closed, position and a second, open position. In the closed position, the ball 20 is urged against the seating surface 22 to close the outlet opening(s) 24 against fuel flow. In the open position, the ball 20 is spaced from the seating surface 22 to allow fuel flow through the outlet opening(s) 24. The closure member 20 is part of the armature tube ball assembly 18 that is connected to an armature (not shown) in the conventional manner. A spring (not shown) biases the armature and thus the valve ball 20 toward the closed position. The valve body 12, armature, and valve ball 20 define a valve group assembly such as disclosed in U.S. Pat. No. 6,685,112 B1, the contents of which is hereby incorporated herein by reference.
The fuel injector 10′ includes an electromagnetic coil (not shown) that is operable, in the conventional manner, to produce magnetic flux to draw the armature and thus the armature tube ball assembly 18 away from the seating surface 22, thereby moving the valve ball 20 to the open position and allowing fuel to pass through the fuel outlet opening(s) 24. Deactivation of the electromagnetic coil allows the above-mentioned spring to return the valve ball 20 to the closed position against the seating surface 22 and to align itself in the closed position, thereby closing the outlet opening(s) 24 against the passage of fuel. The electromagnetic coil is DC operated. The coil is part of a power or coil subassembly such as disclosed in U.S. Pat. No. 6,685,112 B1.
With reference to
With reference to
The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
