Patent Application
20100133363
The invention relates to fuel injectors for vehicles and, more particularly, to a low pressure, heated fuel injector that adds thermal energy into the fuel prior to injection.
To reduce the dependency on mineral oil based fuels, there is currently a great deal of interest in renewable fuels. The present fuel of choice for spark ignition engines is ethanol or mixtures of gasoline and ethanol. Due to the vapor phase characteristics of ethanol, engines running on pure ethanol (E100) or mixtures of ethanol and water will not start below ambient temperatures of 15° C. to 20° C. In markets where mixtures of up to 85% ethanol and gasoline (E85) are legislated, the minimum start temperature is lower at −15° C. to −20° C. In the Brazilian market (E100) minimum required start temperatures are −5° C. to −10° C. and in Sweden and North America −30° C. to −40° C. are typical requirements. This invention addresses this cold temperature start dilemma by heating the injected fuel during start. For these applications, thermal energy must be added to the fuel prior to injection.
The current solution in Brazil (E100) is to have a small underhood gasoline tank and simple cold start injector and pump to inject gasoline into the intake manifold during cold start conditions. The disadvantages of this system include fuel aging during warm months causing a no start condition when the weather gets cold, a fire risk when filling the underhood tank with a hot engine, and the necessity of a second fuel. The current solution for E85 market is a winter blend fuel of E50 or E70 and in Sweden, a block heater. The disadvantages of these solutions include the use of these vehicles in markets were there is no block heater infrastructure, such as the rest of Europe or North America or in unexpectedly cold weather when the winter blend fuel is not available.
Heated fuel injectors have been developed to heat fuel prior to injection. For example, U.S. Patent Application Publication No. 2007/0235557A1 discloses an injector that inductively heats a valve body. In addition to the very rapid heat-up of the valve body facilitated by inductive heating, the advantage of this concept is that all the fuel of the first injection is heated. That is, there is no fuel between the heater and the valve. Among the disadvantages of this concept are limited surface area available for heating (only the inside cylindrical surface of the valve body), so in spite of the rapid temperature rise of the valve body, heat up times are long due to the lack of surface area limiting power input into the fluid. In addition, heavy modifications are required to existing manufacturing equipment to manufacture the configuration.
There is a need to provide an improved fuel injector that adds thermal energy to fuel prior to injection, improves heat transfer efficiency, and reduces manufacturing costs.
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 fuel injector having an inlet tube defining an inlet of the fuel injector. A valve body is associated with the inlet tube to define a fuel passage through the fuel injector. A valve seat is associated with the valve body and includes an outlet opening in communication with the fuel passage. An armature is movable with respect to the valve body between a first position and a second position. The armature is associated with a closure member proximate the outlet opening and engaged with the valve seat when in the first position, and spaced from the valve seat when in the second position. An electromagnetic coil is energizable to provide magnetic flux that moves the armature between the first and second positions to control fuel flow through the outlet opening. A heat exchanger is provided in the inlet tube. A secondary coil is energizable to provide a magnetic field to inductively heat the heat exchanger and thus fuel prior to exiting the outlet opening.
In accordance with another aspect of an embodiment, a method of heating fuel prior to exiting a fuel injector provides a fuel injector having an electromagnetic coil energizable to provide magnetic flux that moves an armature between first and second positions to control fuel flow through an outlet opening of the fuel injector; a secondary coil; and a heat exchanger in an inlet tube. The secondary coil is energized to inductively heat the heat exchanger to heat fuel prior to exiting the outlet opening.
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
A closure member, e.g., a spherical valve ball 28, within the injector 10 is moveable between a first, seated, i.e., closed, position and a second, open position. In the closed position, the ball 28 is urged into engagement with the seating surface 16 to close the outlet opening 18 and prevent fuel flow. In the open position, the ball 28 is spaced from the seating surface 16 to allow fuel flow through the outlet opening 18.
An armature 30 that is axially moveable along axis A in a tube portion 32 of the valve body 12 includes valve ball capturing means 34 at an end proximate the seating surface 16. The valve ball capturing means 34 engages with the valve ball 28 outer surface adjacent the seating surface 16 and so that the valve ball 28 rests on the seating surface 16 in the closed position of the valve ball 28. A spring 36 biases the armature 30 and thus the valve ball 28 toward the closed position. A filter 38 is provided between the inlet end 22 and outlet opening 18 to filter fuel. The fuel passage 23 is such that fuel introduced into the inlet end 22 of the inlet tube 20 passes through the filter 38, over the valve ball 28, and through the outlet opening 18 when the valve ball 24 is in the open position. The valve body 12, armature 30, valve seat 14 and valve ball 28 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.
An electromagnetic coil 40 surrounds a pole piece or stator 42, formed of a ferromagnetic material, coupled to the inlet tube 20. The electromagnetic coil 40 is operable, in the conventional manner, to produce magnetic flux to draw the armature 30 away from the seating surface 16, thereby moving the valve ball 28 to the open position and allowing fuel to pass through the fuel outlet opening 18. Deactivation of the electromagnetic coil 40 allows the spring 36 to return the valve ball 28 to the closed position against the seating surface 16 and to align itself in the closed position, thereby closing the outlet opening 18 preventing passage of fuel. The electromagnetic coil 40 is DC operated and the coil 40 with bobbin 44, and stator 42 are preferably overmolded to define a power or coil subassembly such has disclosed in U.S. Pat. No. 6,685,112 B1.
As shown in
When the coil 48 is energized, the magnetic field from the coil 48 inductively heats only the magnetic heat exchanger 50 (not the inlet tube 20) to preheat fuel in the inlet tube 20 prior to exiting the outlet opening 18 during operation of the fuel injector 10. Thus, the coil 48 and heat exchanger 50 can atomize fuel using inductive heating in the injector 10 where the liquid fuel is vaporized prior to exiting the outlet opening 18 for use during the cold start phase.
The injector 10 can be used for Flex Fuel Start applications to reduce emissions when E100 and E85 are the fuels used. The injector 10 enables efficient vehicle starts with E100 down to temperatures of −5 C with 200 W heating power even if flash boiling is interrupted. In conventional E100 applications as noted above, a vehicle will not start at 20 C and these applications require an additional gasoline tank as a start system.
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 scope of the following claims.
