US3542293A

US3542293A - Fuel injector

Info

Publication number: US3542293A
Application number: US749429A
Authority: US
Inventors: Irving N Bishop; Michael A Choma; Laszlo Hideg; Richard G Mosher; Alador O Simko
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1968-08-01
Filing date: 1968-08-01
Publication date: 1970-11-24
Anticipated expiration: 1987-11-24

Description

United States Patent Inventors Irving N. Bishop, Farmington, and

Michael A. Choma and Laszlo Hideg, Dearborn Heights, and Richard G. Mosher, Dearborn, and Aladar O. Simko, Dearborn Heights, Mich. App]. No. 749,429 Filed Aug. 1, 1968 Patented Nov. 24, 1970 Assignee Ford Motor Company Dearborn, Michigan a corporation of Delaware FUEL INJECTOR 17 Claims, 3 Drawing Figs.

US. Cl 239/95, 239/383, 239/453. 239/533: 123/188 Int. Cl ..F02m 45/10 Field of Search 239/86, 95,

Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Michael Y. Mar Attorney-John R. Faulkner and Glenn S. Arendsen ABSTRACT: An axially movable, outwardly opening valve member seats on an outwardly tapered seat portion in the tip of the fuel injector about 0.005 inch upstream of the seat outer edge. A tension spring located within the fuel passage urges the valve member to its seat and also holds the valve member on the center line of the injector. The spring is designed to resonate the valve member at 250-l,200 cycles per second in stationary air. A rotator fastened to the upstream end of the tension spring utilizes the dynamics of the fuel injection to rotate the valve member.

atentecl Nov. 2,; 1970 ALADAR 0.' S/MKO AT TORNE Y5 FUEL INJECTOR SUMMARY or THE INVENTION Fuel. injectors for reciprocating internal combustion engines must satisfy a variety of requirements throughout a wide flow range for proper engine operation from idling to over 7,000 rpm. Such injectors must start and stop fuel flow uniformly without dripping at the end of the injection cycle, produce a spray having a substantially uniform concentricity throughout each injection cycle at the various fuel flow rates, and perform with a minimum of combustion deposit-buildup. Other practical considerations conductive to commercial acceptance include minimizing wear. insuring that the wear which does occur is uniform, and reducing material and manufacturing costs. i i

The injector of this, invention is particularly useful in a stratified charge type internal combustion engine suchas the engine described in Bishop etaL, U.S. Pat. No. 3,315,650. Accurate fueldelivery over a wide range of flow rates is essential in such an engine, and this injector performs exceptionally well in achieving the optimum performance and economyof the engine. Many features of the injector also are useful in conventional fuel injected reciprocating-type engines.

An elongated body having an inwardly tapering tip portion, a passage extending through the body and tip portion, and an outwardly tapering seat at the opening of the passage form the basic structure of the injector of this invention. An axially movable poppet'type valve member normally seats on the seat portion but is moved away therefrom by fuel pressure. The seat and the valve member are designed so the valve member initially contacts the seat about 0.0020.010 inch from the downstream edge of the seat portion. One end of a tension spring located in the body passage is connected to the valve member, and the otherend is anchored in the body so the spring holds the valve member on the'ccnter line ofthe tip'and the body and draws the valve member toward its seat.

Valve member rotation improves seat life and reduces the buildupof combustion deposits on the injector tip. This rotation is provided by a hydrodynamic rotator connected to the upstream end of the spring. Rotational torque is developed on .I the slanted passages in the rotator by pressure pulses propagating upstream from the vibrating valve member. The spring can be connected to the valve member through an eye arrangement permitting some rotational movement of the spring relative to the valve body. When the valve member is lifted off its seat by fuel delivery, friction on the valve member drops essentially to zero and valve rotation takes place.

Vibrating the valve member during fuel delivery assures good fuel atomization with fuel pressures of 150-800 p.s.i. Valve vibration in the entire load and speed range, including engine startup, is achieved by an essentially zero friction valve guidance arrangement and proper tuning of the spring and valve member assembly with the fuel system communicating with the injector. A spring having a spring rate capable of producing a resonant frequency of the spring and valve as 'sembly in stationary air of about 250l,200 cycles per second produces good valve vibration in the entire operating range. The fuel flow area of the injector and the fuel line also are important in achieving good vibration.

BRIEF DESCRlPTlON OF THE DRAWINGS FIG. 3 is a sectional view showing a less expensive injector having a simplified rotator and a more easily manufactured construction.

' stepping down in a plurality of stages to Referring to FIG. l, a cylindrical valve body 10 has one end exteriorly threaded into an inlet fitting 12. A substantially concentric passage 14 extends through body 10 and commu nicates with the passage 16 in fitting 12. The upstream exterior portion of body i0-has a holder nut 18 slid-ably mounted thereon to fasten the injector into the engine by conventional means.

A tip portion 20 is threadably fastened to the other end of body 10 and thethreaded joint is sealed by a gasket 22. Tip portion 20 necks down to an outside diameter approximately equaling the diameter of passage 14 and contains a passage 23 its final passage 24. Passage l4 communicates with passage 23. A tubular sleeve 25 is fitted in passage 14 and extends into the larger end of the up portion.

Located in the opening of passage 24 is a valve member 26 that has an elongated stem 28 extending upstream through passage 23 and into passage 14. Stem 28 is considerably smaller than passage 23 so it does not restrict fuel flow. The upper end of stem 28 is threaded into an extension 30 that has a small tab 32 on its upstream end. A double chamfered hole 34 is formed in tab 32.

A tension spring 36 having hooked eyes at each end has one eye inserted through hole 34 and the other eye inserted througha similar hole 38 in an anchor rod 40. The double chamfers used on holes 34 and 38 provide knife edges that avoid transmitting any side loads to the valve member. Anchor rod 40 projects through an anchor seat 42 firmly pressed onto a shoulder in sleeve 25 at least 10 valve member diameters upstream frorri the valve member. A valve member diameter, as the term is used herein, is the diameter of the initial contact line between the valve member and its seat. Maintaining the anchor seat beyond this parameter permits the valve member to seek a concentric location during injection and seating.

Seat 42 has an appropriate number of holes 43 sufficient to pass fuel through the injector. A hemispherical bearing member 44 is positioned on rod 40 above seat 42 with its hemispherical surface contacting a conical portion 45 formed on the upstream side of seat 42, and a valve rotator 46 is mounted on rod 40 just upstream of member 44. Rotator 46 has a plurality of passages-41 located near its outer periphery and angled 45 relative to the body centerline. An anchor nut 48 and a jam nut 50 are threaded onto rod 40 to hold the rotator and bearing member in place. Bearing member 44, rotator 46 and anchor nut 48 can be of one-piece construction if desired.

Sleeve 25 terminates a short distance upstream of the upper endof anchor rod 40 and a hollow filter carrier 52 seats on the upper end of the sleeve. A filter 54 seats in a counterbore in the upstream end of carrier 52 and is held in place by an elongated spacer 56 spring loaded in the downstream direction by a compressive spring 58 seating in inlet fitting 12.

Turning to the enlarged view of the injector tip shown in FIG. 2, the exterior surface 60 of tip portion 20 tapers inwardly and intersects an outwardly tapering valve seat 62 at a substantially right angle. Stem 28 flows smoothly into a spherical surface 64 that serves as the seating surface of valve member 26. Spherical surface 64 terminates at a point corresponding to the downstream edge of seat 62, and the exterior surface 61 of valve member 26 then tapers inwardly at the angle of surface 60 until reaching the approximate diameter of stem 28. Exterior surface 61 then flows smoothly into a short cylindrical portion 66 that has a diameter approximately equaling the diameter of stem 28. A small hole 68 can be formed in cylindrical portion 66 to assist in assembly if desired.

Surface 61 of the valve member and surface 60 of the tip portion in the vicinity of the downstream edge of the seat are parallel to each other arid preferably are coplanar within very close tolerances, usually about 0.0003 inch. This arrangement provides worthwhile benefits in reducing deposits on the tip. lt is preferable to have the valve member about 0.0002 inch larger than the tip portion initially. since valve seat wear then tends to match up the exterior surfaces.

Valve seat 62 is outwardly conical and spherical surface 64 is designed to contact seat 62 initially at a contact line about 0.005 inch from the downstream edge of seat 62. As the valve or seat wear. this contact line ofcourse becomes a contact surface. Each of the swivel joints provided by the end connections of spring 36 assist in eliminating any forces that cannot be resolved along the center line of valve member 26. Such forces would tend to cock the valve member and thereby produce an asymmetrical spray pattern. cause uneven seat wear. and destroy the parallelism of surfaces 60 and 61.

The size of valve member 26 is selected so there is a minimum of 0.0003 inch means valve lift at the minimum or idling flow rate and a maximum of 0.005 inch means valve lift at the maximum flow rate. Skip cycling at and near the idling flow rate is avoided by maintaining the valve size above this minimum; the maximum valve lift insures that the fuel sheet issuing from the injector does not become too thick to be atomized when the pressure drop through the injector is below 800 p.s.i.. and assists in keeping the valve member concentric so the fuel sheet is approximately equal on all sides.

Stem 28 is considerably smaller than corresponding portions of passages 14. 23 and 24. and guidance of valve member 26 is provided entirely by the anchor rod assembly acting through the spring. Thus the valve member itself is not subjected to any mechanical guidance. and it can sway or rotate freely to seek a concentric position. Seat 42 preferably locates spherical bearing member 44 within 5' from a point on the centerline ofthe valve member.

Axial vibration of valve member 28 during injection assures proper fuel atomization with a pressure drop across the injector of l50-800 p.s.i. Adequate valve vibration is achieved with the zero friction guidance arrangement of the valve member by selecting a spring 36 having a rate sufficient to vibrate the valve member in stationary air at a frequency between 250 and 1.200 cycles per second. During fuel delivery the vibrating frequency can be outside of this range because of the effect of the fuel. For proper vibration and delivery, the fuel flow area of the injector for a distance 46 inches upstream ofthe valve member should be 1-3 times the valve diameter squared. In addition. the flow area of the fuel line should be such that theproduct of the maximum fuel flow rate of the pump in cubic inches per second and the line flow area in square inches isbetween-0.0l and 0.03.

The reverse pressure pulse passing upstream through passage 14 when the valve member stops fuel delivery acts on passages 47 in the valve rotator 46 to exert a rotating torque on the anchor rod assembly while simultaneously reducing the load between bearing member 44 and seat 42. The reduced friction between bearing member 44 and seat 42 permits a slight windup of anchor rod assembly 40 that is temporarily absorbed by the ends of spring 36. When the next vibration or injection cycle opens valve member 26. the essentially zero friction of valve member 26 permits the slight torque to rotate the valve member. Because of the valve member vibration. satisfactory rotation also can be achieved with a rigid connection between the rotator and the valve member.

In the less expensive injector shown in FIG. 3. components identical to those of FIG. 1 are designated by the same numerals and only changed and new components are described below. Tip portion 20' is press fitted into body Valve member 26 has a shortened stem 28' that is soldered to a wire 70. Wire 70 has a book 72 at its upstream end that engages the lower eye of a spring 36. Anchor seat 42 is pressed onto a shoulder in body 10 and the upper end of spring 36' extends through anchor seat 42 and an assembly consisting of bearing member 44', rotator 46'. and a fastener 74. This assembly is fastened to spring 36' by an adhesive such as Locktite". which also can be used to fasten tip portion to body 10'. Filter 54 is pressed onto a shoulder in body 10' upstream of the rotator assembly.

In place of spherical surface 64. valve member 26 can have a double cone surface in which the inner cone terminates at the desired seat point and the outer cone projects downstream at a slightly sharper angle. The sphere-on-cone construction shown in FIG. 2 is preferred in most instances over such a cone-on-cone construction, however. because a higher surface finish can be achieved by lapping spherical surface 64.

Thus this invention provides a fuel injector capable of extremely accurate fuel delivery over a wide range of flow rates. Painstaking engineering accommodates all performance requirements and the injector produces a uniform cone of fuel at each flow rate for the life of the engine. The initial contact line of the valve member on its seat prevents asymmetrical spray and deposit buildup. the guidance and spring arrangement insures valve member vibration and fuel atomization, and the coplanar relationship of the exterior surfaces ofthe tip and the valve member in the vicinity of the seat also assists in preventing deposits.

We claim:

1. A fuel injector comprising:

an elongated body having an inwardly tapering tip portion. a

passage extending through said body and tip portion and an outwardly tapering seat portion at the opening of said passage in said tip portion; an axially movable valve member normally seated on said seat portion but movable away therefrom. said valve member initially contacting said seat portion about 0.0020.0l0-inch from the downstream edge of the seat portion; spring means located in said passage. said spring means having one end connected to said valve member to urge the valve member into contact with the seat portion; and

rotator means located in said passage for utilizing the dynamics of fuel injection to apply a rotating torque to the valve member said rotator means being connected to the opposite end ofsaid spring means.

2. The injector of claim 1 in which the exterior surface of the tip portion and the exterior surface of the valve member in the vicinity of the downstream edge of the seat portion are coplanar within 0.0003 inch to reduce combustion deposits.

3. The injector of claim 2 in which the valve member has a mean lift of about 0.0003 inch at engine idling and about 0.005 inch at maximum fuel flow.

4. The injector of claim 3 in which the spring means is capable of vibrating the valve member at a rate of 250l.200 cycles per second in stationary air.

5. The injector of claim 4 in which the seat portion forms es sentially a right angle with the exterior surface of the tip portron.

6. The injector of claim 5 comprising an anchor seat fastened to said body upstream of said valve member and a bearing member seating on the upstream side of said anchor seat, and said spring means is a tension spring having one end connected to said bearing member and the other end connected to the valve member.

7. The injector of claim 6 in which the rotator means is fastened to said anchor member. said rotator means comprising passages angled relative to the axis of the injector. said spring means providing a slight angular loosencss between said bearing member and'said valve member, said rotator means reacting to a reverse pressure wave to wind the rotator means slightly relative to the valve member when fuel delivery stops. said winding rotating the valve member when fuel delivery resumes.

8. The injector of claim 7 in which the spring means is fastened to the valve member by a double-chamfered hole that permits the slight angular looseness.

9. The injector of claim 8 in which the seat portion of the tip portion is outwardly conical and the seating surface of the valve member is spherical.

10. The injector of claim 1 in which the spring means is capable of vibrating the valve member at a rate of 250 l ,200 cycles per second in stationary air.

11. The injector of claim 1 comprising an anchor seat fastened to said body upstream of said valve member and a bearing member seating on the upstream side of said anchor seat. and said spring means is a tension spring having one end connected to said bearing member and the other end connected to the valve member.

12. A fuel injector for a reciprocating internal combustion engine comprising:

an elongated body having an inwardly tapering tip portion, a passage extending through said body and tip portion and an outwardly taperingse'at portion at the opening of said passage in said tip portion;

an axially movable valve member normally seated on said seat portion but movable away therefrom by fuel pressure in said passage; 5

an anchor seat located in said passage and fastened to said body upstream of said valve member;

a bearing member normally seated on the upstreamside of said anchor seat ,said bearing member being rotatable relative to said anchor seat;

a tension spring connecting said bearing member and said valve member. said tension spring being capable of 'the valve member is spherical, said seating surface initially contacting said seat portion about 0.0020.0l0 inch from the downstream edge of the seat portion.

15. The injector of claim 14 comprising a filter means located within said bodyupstream of said anchor seat.

16. The injector of claim 15 in which the spring is bonded to the bearing member and has an eye engaging a tab fastened to the valve member.

17. The injector of claim 16 in which the valve member has a mean lift of about 0.0003 inch at engine idling and about 0.005 inch at maximum fuel flow.