Temperature Controlled Unit Injector

Technical Field

This invention relates generally to internal combustion engines and more particularly to temperature control in oil engines having forced oil supply.

Background Art

The nozzle or tip end of a unit fuel injection device is adjacent the combustion area of a cylinder and is therefore exposed to operate in a high temperature environment. Temperature control of the tip or nozzle end usually involves the use of fluids and maintaining control is advantageous to assure proper functioning of the fuel injector. One problem in providing proper tem- perature control is. moving a sufficient amount of fluid to assure adequate temperature control. Obviously, the greater the volume of fluid moved, the greater the tem¬ perature controlling effect.

Supplying a greater volume of fluid involves enlarged fluid passageways. These passageways are usually provided in the various- parts of a unit injector housed in a retainer sleeve. During assembly of these parts, time-consuming care must be taken to properly align the passageways. Enlarged passageways require additional space which results in a need to enlarge the unit in¬ jector and, since space is critically limited, it is difficult to provide adequately enlarged passageways.

In view of the above, it would be advantageous to provide a unit injector which provides adequate tem- perature control, avoids excessive use of critical space, avoids time-consuming assembly problems, and which over¬ comes the problems associated with the prior art.

Disclosure of Invention

In one aspect of the present invention, the problems pertaining to the known prior art, as set forth above, are advantageously avoided. This is accomplished by providing a temperature controlled unit fuel injector including a retainer sleeve having a nozzle end and means for conducting fluid toward and away from the nozzle end. Fluid is conducted into a circumferential groove cooperating with an axial passage for moving fluid adjacent the nozzle end of the fuel in¬ jector. The circumferential groove and the axial passage are formed in the outer peripheral surface of the retainer

The foregoing and other advantages will become apparent from the following detailed description of the invention when considered in conjunction with the accom¬ panying drawings. It is to be expressly understood, how¬ ever, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

Brief Description of the Drawings

In the drawings:

FIGURE 1 is a graphic view illustrating a portio of a fuel injection system;

FIGURE 2 is a graphic view illustrating a portio of an alternative fuel injection system;

FIGURE 3 is a cross-sectional view illustrating an embodiment of the present invention;

FIGURE 4 is a cross-sectional view taken along line IV-IV of Figure 3 and illustrating the circumferen- tial groove including separating plugs; and

FIGURE 5 is a side elevation generally illus¬ trating the present invention.

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Best Mode for Carrying Out the Invention

Referring now to Figure 1, a portion of a fuel injection system is graphically represented including an engine 10 having one of several unit injectors 12 mounted therein adjacent a respective cylinder (not shown) of engine 10. To establish a reference cycle, a tank 14 supplies fluid such as fuel to a transfer pump 16 via an appropriate conduit 18. Pump 16 supplies fuel to fuel injector 12 at a substantially low pressure. Some of the fuel from pump 16 is directed, via conduit 20, to fuel injector 12 to be injected into the respective cylinder. Other of the fuel from pump 16 is directed to fuel injector 12, via concuit 22, as a tem¬ perature controlling fluid, in- this instance for cooling injector 12. The cooling fuel is then directed from in¬ jector 12 back to tank 14 via conduit 24 for further cooling substantially to ambient temperature and the cycle is repeated.

If the output of pump 16 is. at too great a rate, optional flow restrictors 26 may be used in either or both conduits 20,22 to control the fuel flow between pump 16 and injector 12.

A medium other than fuel may be used for cooling; however, such would require an additional tank, pump and additional conduits. An element such as a heat exchanger 28 may be used to supplement cooling.

As an alternative, Figure 2 graphically illus¬ trates that a fluid may be supplied to heat the fuel in¬ jector 112 in some instances. A system is anticipated including an engine 110 having one of several unit fuel injectors 112 mounted therein adjacent a respective cylinder (not shown) of engine 110. Such an engine may use a thicker, less viscous residual type fuel stored in tank 114. Such fuels could be heated by a supplemental

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element such as a heat exchanger 128 to thin or reduce the viscosity of the fuel. The fuel could then be supplied to injector 112 by pump 116. In this situation cooling of the tip is of increased importance. A separate fluid could be stored in tank 214, cooled by a heat exchanger 228 and supplied to injector 112 by an alternate pump 216. This separate fluid could be conventional fuel or some other fluid and could be used to supply cooling or in some instances to supply heat to injector 112 by some arrangement such as, for example, injecting steam into heat exchanger 228, on command, by actuating a valve 230. Presence of a heated fluid in injector 112 could avoid congealing of the re¬ sidual fuel in the event of a rapid shutdown of engine 110 occurring without an opportunity to purge the unit injector of high viscosity fuel prior to shutdown.

In Figure 3, a cylinder head 32 includes well known cooling passages 34 which are formed in the head. A unit injector 12 is seated in head 32 including .a nozzle end 36 terminating at a tip 38 adjacent a cylinder (not shown) .

Well known elements of fuel injector 12, such as plunger 39, barrel 40, spring cage 42, lift stop 44 and tip assembly 46, to name a few, are housed in a "retainer" sleeve 48 seated in head 32 at sleeve bore

50. Also, as it is known, means are provided in head 32 for conducting injection fluid to tip 38 of nozzle end 36. Such means includes supply ports 60 (Fig. 4 also), annular groove 62, filtered inlets 64, port 66, bore 68 and nozzle bore 70. Groove 62 is positioned to be aligned with ports 60 when tapered abutment 61 of sleeve 48 con¬ tacts tapered seat 63.

Means are provided for conducting temperature controlling fluid, whether heated or cooled, toward and

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away from nozzle end 36. A portion of such means in¬ cludes, but is not limited to, a circumferential groove 52 and an axial passage 54 formed in outer peripheral surface 56 of retainer sleeve 48 by machining or the like. It is preferred that axial passage 54 include two inlet passages 54a,b and two outlet passages 54c,d (best shown in Fig. 4) .

Groove 52 is positioned to be aligned with inlet-outlet ports 58 (Fig. 4 also) formed in head 32 when tapered abutment 61 of sleeve 48 contacts tapered seat 63. Either of the ports 58 can be an inlet or out¬ let for a temperature controlling fluid depending on a desired direction of flow. For purposes of this dis¬ cussion, the inlet will be designated 58a and the outlet will be designated 58b.

Another portion of the means for conducting temperature controlling fluid toward nozzle end 36 includes passages formed in tip assembly 46, described as follows: the inlet passages 54a,b extend from groove 52 to tip inlet annulus 74 via two respective temperature control inlet bores 76 (only one shown) and then to tip temper¬ ature control annulus 78 via two tip inlet passages 80 (only one shown) . Temperature controlling fluid in tip temperature control annulus 78 is then communicated to tip outlet annulus 82 via two tip outlet passages 84

(only one shown) . From annulus 82, temperature control fluid is communicated to outlet passages 54c,d via two respective temperature control outlet bores 86 (only one shown) . The use of two of each of the above-described temperature controlling fluid passages permits additional fluid volume to be moved through the injector 12. Single, enlarged passages could be formed as axial bores through retainer sleeve 48 but would require enlarging the overall size of the injector 12. Forming the axial passage 54 in

the outer periphery 56 of retainer sleeve 48 permits sleeve 48 to handle added volume of temperature con¬ trolling fluid without the need to increase the size of retainer 48 such as by increased wall thickness. Means are provided for limiting leakage of temperature controlling fluid from passage 43. Such means comprises axial sealing grooves formed in outer periphery 56 of retainer 48 and are substantially par¬ allel with the axial passage 54 (see Fig. 5) . It will be noted that sealing grooves 90 preferably extend from circumferential groove 52 to chamfer 92. Ideally, passages 54a,b are each situated between a pair of such sealing grooves 90 as illustrated in Figs. 4 and 5. A sealing member 94, resistant to fuel contamination, such as one formed of a fluorocarbon ^' rubber, is provided in each groove 90 to seat against sleeve bore 50 of head 32. Clearance between sleeve 48 and bore 50 is approx¬ imately .008 inches.and even without seals 94 only 10% of fuel in passages 54a,b was found to bypass to passages 5 ^' 4c,d. However, seals 94 are preferred.

Means are provided for separating one portion 52a of groove 52 from another portion 52b. Such means comprise sealing plugs 96 preferably formed of a fluoro¬ carbon rubber, impervious to deterioration due to fuel contamination, and being squeeze or force fitted into groove 52 to seat against bore 50 and limit mingling of fluid in portion 52a with fluid in portion 52b.

Industrial Applicability

Temperature controlling fluid, either heated or cooled as above described, is conducted through head

32 via inlet 58a to inlet portion 52a of groove 52 guard¬ ed by sealing plugs 96. Inlet fluid is then conducted via two axial passages 54a,b toward nozzle end 36 and then through two inlet bores 76 to annulus 74. Two other

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inlet passages connect annulus 74 with tip annulus 78. Fluid is carried away from annulus 78 via two outlet passages 84 to outlet annulus 82. From there the fluid is routed through two outlet bores 86, two axial outlet passages 54c,d and then confined to outlet portion 52b of groove 52 due to sealing plugs 96. The fluid then exits injector 12 through outlet 58b formed in head 32.

The foregoing has described a temperature con¬ trolled unit fuel injector including a retainer sleeve having a nozzle end and means for moving temperature controlling fluid toward and away from the nozzle end. Increased volumes of temperature controlling fluid are provided to the nozzle end without the need to enlarge the size of the unit fuel injector.