US 3762378 A
In an internal combustion engine, a fuel injector having a valve with an elongated hollow stem which functions as a conduit for fuel being delivered to the valve opening. A heater probe is telescopically disposed in the stem to preheat the fuel. The valve is biased by a calibrated spring arrangement that is suited for automatic assembly.
Description (OCR text may contain errors)
[ 1 Oct. 2, 1973 l l FUEL INJECTION MEANS AND PROCESS FOR MAKING SAME  Inventor: Frank E. Bitonti, 8337 Esper,
Detroit, Mich. 48204  Filed: Nov, 8, 1971 I21] Appl. No.: 196,624
3,630,184 12/1971 Wolf 123/145 3,648,669 3/1972 Rank 123/32 FOREIGN PATENTS OR APPLICATIONS 1,118,430 10/1954 France 123/34 A 890,851 2/1943 France 123/32 H Primary ExaminerLaurence M. Goodridge Assistant Examiner-Ronald B. Cox Attorney-Charles W. Chandler  ABSTRACT In an internal combustion engine, a fuel injector having a valve with an elongated hollow stem which functions as a conduit for fuel being delivered to the valve opening. A heater probe is telescopically disposed in the stem to preheat the fuel. The valve is biased by a calibrated spring arrangement that is suited for automatic assembly.
8 Claims, 4 Drawing Figures  U.S. Cl. 123/32 II, 123/34 A, 123/122 E  Int. Cl. F02b 3/00, F02m 31/00  Field of Search 123/32 H, 34 A  References Cited UNITED STATES PATENTS 2,435,213 2/1948 Hancock 123/34 A 1,375,646 4/1921 1361111516.... 123 32 H 1,269,989 6/1918 Williams 123 32 1,597,060 8/1926 Crossley 123 32 2,108,706 2/1938 Crillon 123/34 52 sounc: 0F ELECTRICAL POWER a? e l 14W /4 1 T l F :4
' 25 4 l l 22 l /a l FUEL SOURCE 0F 1 PUMP FUEL PMENTED 081 2 I973 SHEET 1 UF 2 FUEL INJECTION MEANS AND PROCESS FOR MAKING SAME BACKGROUND OF THE INVENTION This invention is related to fuel injectors for internal combustion engines and more particularly to an injector assembly having a valve for discharging fuel that is heated as it passes through the valve stem, and to a process for mounting a spring assembly on such a valve stem.
Some internal combustion engines employ means for injecting metered amounts of fuel into a combustion chamber where the fuel is ignited by suitable means. The injector valve is opened in response to fuel pressure and closed by a spring. The spring bias is usually calibrated and mounted in position by a timeconsuming hand assembly process.
In order to ignite properly during cold weather, the fuel used by fuel injectors must be preheated. Although electrical heaters have been disclosed in the art for preheating the fuel until the engine reaches its operating temperature, an injector that allows the fuel to be in contact with such a heater in a position adjacent the discharge opening into the combustion chamber has not been commercially available.
SUMMARY OF THE INVENTION The preferred embodiment of the invention is described as a component of a hypergolic injection system in which the pressure and temperature of the fuel in the injector is such that it spontaneously ignites upon being delivered into contact with oxygen in the air in the combustion chamber. The injector has a body mounted in the engine head with an outlet opening adjacent the engine combustion chamber. An electrical heater is mounted in the body with an elongated probe disposed adjacent the outlet opening. A valve having a hollow stem is telescopically mounted on the heating probe to provide a passage having an annular cross section in the stem for fuel passing to the outlet opening.
An inlet opening in the injector body receives fuel which is passed into the valve stem so as to be heated until the valve is opened in response to fuel pressure. As the valve is opened, the fuel passes from the valve stem and through the outlet opening.
The injector is assembled by mounting an annular retainer, that also functions as a valve seat, on the valve stem. A spring is then mounted on the stem and then a second retainer. The spring is compressed by the second retainer according to the fuel pressure that is to open the valve. The second retainer is then welded to the stem by an electron beam to form a calibrated valve assembly. The valve assembly is disposed in the body and the first retainer welded by an electron beam to the injector body.
The preferred injector is composed of a relatively few parts that can be assembled in an automated assembly line to provide injectors having reasonably uniform operating characteristics. The position of the heater ensures an efficient transfer of heat to the fuel as the injector valve is being opened and closed. Still further objects and advantages will become readily apparent to those skilled in the art of the invention upon reference to the following detailed description.
DESCRIPTION OF THE DRAWINGS The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views, and in which:
FIG. 1 is a fragmentary, sectional view of an internal combustion engine having a fuel injector illustrating the preferred embodiment of my invention;
FIG. 2 is an enlarged view of the injector valve showing the manner in which the valve head is welded to the stem;
FIG. 3 is a view showing the spring being mounted on the valve; and
FIG. 4 is a view showing the manner in which the valve assembly is mounted on the injector body.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, an engine housing 10 is illustrated in FIG. 1. A head 12 is mounted on housing 10 to provide a combustion chamber 14 and an exhaust passage 16 for the removal of combustion products from chamber 14. A piston 18 is disposed in housing 10 to function as a power member in the manner well known to those skilled in the art.
Fuel injector 20 is mounted on head 12 for delivering metered amounts of fuel to combustion chamber 14. An exhaust valve 22 is mounted adjacent the fuel injector for opening and closing communication between the combustion chamber and exhaust passage 16.
For illustrative purposes, the preferred fuel injector provides fuel for chamber 14 which ignites as a result of being heated above its ignition temperature and then being introduced into an environment having a lower pressure than in the injector and sufficient oxygen to support combustion. This fuel delivery method is known as hypergolic injection. The object is to ignite the fuel before it reaches the combustion chamber walls to eliminate the quenching effect that is a cause of air pollution by conventional engines. However, the preferred injector can be employed in other types of internal combustion engines.
The fuel system comprises deliverying the fuel from a source 24 through conduit means 26 by means of pump 28. Conduit means 26 includes a spiral coil 30 disposed in exhaust passage 16 to heat the fuel before it is received by injector 20.
Injector 20 has an elongated hollow body 32 with a longitudinal bore 34 for receiving fuel through an inlet 36. A hollow elongated retainer 38 is mounted at the lower enlarged end of bore 34, and has a threaded section mounted in head 12. A valve having a head 40 mounted on the end of an elongated hollow stem 42, is slideably mounted in retainer 38. Valve head 40 is movable between a closed position illustrated in solid lines in FIG. 1, and an open position illustrated in phantom. In its closed position, the valve head is engaged with a tapered seat formed on the end of retainer 38 In its open position, valve head 40 has a tapered neck 44 to provide a cone-shaped charge of fuel into the combustion chamber. The fuel passes from inlet 36 to stem 42 and then passes the length of the stem to a series of openings 46 located adjacent head 40.
A spring 48 is mounted on stem 42, one end being engaged with retainer 38 and its other end engaged with a second retainer 50 mounted on the end of the stem. Spring 48 is pre-loaded when the fuel injector is being assembled to bias valve head 40 toward its closed position and to open in response to a predetermined fuel pressure applied on the tapered neck of the valve head.
An electrically energized heater having an elongated probe 52 is disposed in body 32. The lower end of probe 52 is disposed in valve stem 42 adjacent openings 46. The diameter of heater probe 52 is less than the bore of valve stem 42 to form a fuel passage having an annular cross-section. As the fuel passes through the stem, it is in contact with the heater probe until being discharged from the stem in response to opening of valve head 40. Thus, the heater probe provides a relatively large surface area in contact with the fuel and also functions as a sheath to protect an internally housed heating element (not shown) from direct contact with the fuel.
A plug 56 is engaged with the outer end of heater probe 52 to support it in body 32. A lead 60 connects heating probe 52 to a source of electrical power 64. Heater probe 52 is energized to heat the fuel when the engine is being started and under those conditions when the heat transferred to the fuel passing through coil 30 is insufficient to heat the fuel to its ignition temperature at the injector outlet.
A retractor valve 66 is located in conduit means 26 adjacent coil 30 to maintain the fuel pressure in injector above the critical pressure of the fuel but below the opening pressure of valve head 40 between pressure impulses.
Preferably injector 20 is assembled as follows: Referring to FIG. 2, valve stem 42 is formed of metal tubing. Head 40 is joined to the end of stem 42 by electron beam welder 68. The welded seam is ground smooth, and then openings 46 formed by any suitable means. Advantages of using the electron beam welder is that the weld joint can be formed without weld metal and with little heat distortion.
Referring to FIG. 3, retainer 38, spring 48 and retainer 50 are mounted on stem 42. With valve head 40 seated in its closed position in the end of retainer 38, retainer 50 is moved toward retainer 38 until spring 48 is preloaded according to the fluid force that is to open valve 40. Retainer 50 is then joined to stem 42 by electron beam welder 68 to complete the calibrated valve assembly.
Then the valve assembly is disposed in body 32 as illustrated in FIG. 4. Retainer 38 is connected to the end of body 32 by electron beam welder 68 to complete the assembly.
The preferred fuel injector is threadably mounted in engine head 12 to permit removal for cleaning or maintenance in the manner of a spark plug. Similarly, heating probe 52 is removable from its position in body 32 without the necessity of dismantling the remainder of the fuel injector.
Having described my invention, 1 claim:
1. In an internal combustion engine, the combination comprising:
an engine housing having a combustion chamber therein;
a power member movably disposed in the combustion chamber;
fuel injection means for deliverying fuel to said chamber for combustion including:
a body mounted on said engine housing, said body having an inlet for receiving fuel, and an outlet for the passage of fuel from the body toward the combustion chamber;
a valve member mounted in the body adjacent said outlet so as to be movable toward an open position to allow fuel passage through the outlet;
a bias member mounted in the body and connected to the valve member to urge it toward a closed position to block fuel passage through the outlet;
an elongated valve stem connected to the valve member, and having an inlet for receiving fuel, and an outlet adjacent the valve member for passing fuel; and
electrically operated heating means mounted on the body, including an elongated heating probe disposed in the inlet of the valve stem, the heating probe having a length such that it is disposed adjacent the outlet of'the valve stem at such times as the valve member is disposed in said closed position.
2. A combination as defined in claim 1, including a pump connected to the inlet of said body for deliverying fuel at a pressure sufficient to move the valve member toward said open position.
3. A combination as defined in claim 1, in which the valve member has a frusto-conical surface engageable with a seat having a complementary shape.
4. A combination as defined in claim 1, in which the body has an annular retainer with a bore slideably receiving the valve stem, the retainer being shaped to seat the valve member in said closed position.
5. A combination as defined in claim 4, including a bias member engaged with the retainer and a second retainer mounted on the valve stem so as to be movable therewith, the second retainer being engaged with the bias member and so spaced with respect to the first mentioned retainer whereby the bias member prevents motion of the valve member from said closed position unless fuel of a predetermined pressure urges the valve member toward said open position.
6. A combination as defined in claim 1, in which the valve stem is moved with respect to the heating probe as the valve member is moved from its open toward its closed positions.
7. A combination as defined in claim 1, including a source of fuel, heat exchanger means, and a fuel pump for deliverying fuel from said source through the heat exchanger means to the inlet of said body.
8. A combination as defined in claim 7, in which the heat exchanger means includes a head having an exhaust passage for passing combustion products from the combustion chamber, and a conduit for receiving fuel from the fuel pump, the conduit forming a coil disposed in the path of combustion products being passed through the exhaust passage.