US3442456A - Injection nozzle - Google Patents

Description

May 6, 1969 l.. D. THOMPSON ETAL INJECTION NOZZLE Filed Nov. l. 1966 ATTO/@MEV United States Patent O U.S. Cl. 239-533 6 Claims ABSTRACT F THE DISCLOSURE -An injection nozzle has a valve body housing a valve head and a valve seat with a valve retainer such as a metal rod firmly holding the valve head on its seat; means are provided for supplying a liquid (such as fuel) to the valve head under a pressure suiiiciently high to open the valve head from its seat by elongating the retainer rod but well within the limit of elasticity of the rod.

This invention relates generally to injection nozzles, such as those employed for spraying fuel into the cylinders of an internal combustion engine, and more specifically to an outwardly-opening, orifice type nozzle wherein the valve is retained in a preloaded, closed condition by a uniform-stress spring comprising a straight wire or other similar member under tension so that valve opening is effected by straining the wire `within its elastic limit.

'Nozzles are reviewed in chapter 9, Fuel Injection and Controls for IInternal Combustion |Engines (1962), wherein the authors, Paul G. IBurman and Frank De Luca, discuss various types of nozzles such as the (a) open, (b) closed, inwardly-opening and (c) closed, outwardlyopening types, as well as various details and modifications thereof.

While these prior art nozzles undoubtedly perform their intended functions, there is need for improvement. For example, most, if not all, of these prior art nozzles include a valve that is preloaded by a helical coil spring in which the stress, across the cross-sectional area of the spring material, is obviously not uniform at any particular value of F, so that the well known equation, S=F/A, doesnt apply. This being so, the volume of spring material is not utilized to its maximum eiiiciency, resulting in greater moving mass and increased stresses, such as at the valve seat and valve stop. Obviously, a helical coil spring must have a greater diameter than the wire from which it is made, which necessarily requires a larger diameter nozzle assembly and limits engine designers as to the configuration of various adjacent engine components, such as the intake and exhaust valves, etc. Furthermore, these prior art injection nozzles involve moving parts which, in order to prevent leakage and eliminate the need for internal drain lines, requi-re precision lapped mating surfaces, adding considerably to their cost of manufacture and maintenance and friction factors to the operation thereof.

Accordingly, a primary object of this invention is to provide a more eflicient and less expensive injection nozzle assembly.

Another object of the invention is to provide such a nozzle assembly in which the nozzle valve is preloaded by a more etiicient, uniform-stress member, thereby permitting a nozzle design of relatively small outer diameter.

Another object of the invention is to provide such a nozzle assembly in Iwhich the uniform-stress member is a wire or other similar member strained longitudinally within its elastic limit.

Another object of the invention is to provide an outwardly-opening, orifice type nozzle assembly, including a uniform-stress member for preloading t-he valve.

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Still another object of the invention is to provide such a nozzle assembly that is fail-safe in that the valve cannot be injected into the engine combustion chamber in the event of spring failure. In the event spring failure does occur, the nozzle will continue to operate as an open type nozzle.

- Another object of the invention is to provide such a nozzle assembly wherein the structure preventing injection of the valve into the cylinder also serves as the valve stop anid a poppet type seal to prevent leakage around the open va ve.

Another object of the invention is to provide such a nozzle assembly that is characterized by a very short stroke and low moving mass, as compared to prior art nozzles, so as to reduce the time required for the valve to move from its closed position to its fully open position aginst the poppet type seal preventing leakage around the va ve.

A still further object of the invention is to provide such a nozzle assembly wherein leakage around the opening valve and into the combustion chamber is reduced by reason of a tortuous path through which any leakage fuel must travel.

Another object of the invention is to provide such a nozzle assembly which can be assembled, to a large extent, from commercially available components, so as to require a minimum of costly machining, and in which close lit areas are held to a minimum.

Another object of the invention is to provide such a nozzle assembly that does not require lapped pistons thereby materially reducing the manufacturing cost.

Another object of the invention is to provide such a nozzle assembly wherein simple novel means are provided for retaining the components thereof in a particular relation to provide an unsymmetrical orifice type nozzle.

Another object of the invention is to provide such an assembly wherein the nozzle holder is not subjected to pressure vessel type stresses, but must only have adequate thread preload to prevent separation and may therefore be made from lower strength, lighter and more easily machined materials, such as aluminum.

Another object of the invention is to provide a nozzle assembly wherein valve opening pressure and stroke are easily and independently adjustable, the former -without removing the nozzle from the engine.

Another object of the invention is to provide such a nozzle assembly having a high spray orifice to leakage path area ratio, thus insuring that the spray orifice is the domineering orifice or flow path and substantially eliminating or reducing the effect of any cylindrical or conical spray patterns that might possibly occur.

A still further object of the invention is to provide such a nozzle assembly wherein limited leakage around the valve to the poppet seal provides squish or squeeze damping of the valve.

Another object of the invention is to provide such a nozzle assembly wherein engine cylinder pressure acts on a relatively large valve area to reduce or eliminate rebound of the closing valve and maintain the valve tightly seated, thus preventing seat leakage; that is, the nozzle assembly is characterized by a large unbalanced area eX- posed to the combustion chamber which reduces after injection andY results in a sharp cut-off.

Another object of the invention is to provide such a nozzle assembly 4wherein flow efficiency upstream of the spray orifice is improved due to a straight flow path, thereby increasing the overall efliciency thereof.

Still another object of the invention is to provide such a nozzle assembly wherein the injected fuel provides more etiicient cooling of the nozzle components, eliminating the complication of cooled nozzles and the problems attributable t inadequate cooling.

These and other objects and advantages of the invention will become apparent upon reference to the following specification and the accompanying drawings wherein:

FIGURE l is a top plan view of a nozzle assembly embodying the invention;

FIGURE 2 is a cross-sectional view taken on the plane of line 2-2 of FIGURE 1, and looking in the direction of the arrows;

FIGURE 3 is a cross-sectional view taken on the plane of line 3-3 of FIGURE 2, and looking in the direction of the arrows;

FIGURES 4 and 5 are schematic illustrations of the nozzle assembly of FIGURE 2 mounted in an engine;

FIGURE 6 is a fragmentary portion of FIGURE 2, illustrating a modifiication of the invention.

Referring now to the drawings in greater detail, FIG- URE l is a substantially actual-size top plan view of the nozzle assembly 10, while FIGURE 2 is an enlarged cross-sectional view. The nozzle 10 comprises a so-called nozzle holder 12 having a larger diameter vpassage 14 and an axially aligned smaller diameter passage 16 formed therethrough, the upper portion 18 of the larger diameter passage being threaded. The holder 12 is also Iformed with oppositely disposed ears 20 having openings 22 therein to receive bolts 24 by which the holder 12, and thus the nozzle 10, is secured to the engine 26. Except for the ears and other minor details, the nozzle 10 structure is of substantially cylindrical configuration so that the cross-sectional view of FIGURE 2 is descriptive of the structure.

The holder 12 is thus adapted to receive the nozzle subassembly 28 comprising an outer tube 30 fitted with or receiving therein an inner tube 32, both of which may be fformed from commercially available steel tubing, the outer tube 30 having an external diameter of approximately 34", for example.

Where the outer tube 30 is made from commercially available tubing, it is fitted with an external flange 34, which may be a ring brazed in place. The internal passage 36 may be slightly enlarged by machining so as to leave the smaller diameter portion 38 at the lower end thereof, and the lower free end thereof may be formed in any suitable manner with an inwardly extending annular shoulder 40 and a short smaller diameter opening 42 for a purpose to be described.

The inner tube 32 is likewise provided with an outer flange 44 at the upper end thereof having substantially the same outer diameter as the flange 34 on the outer tube 30, the upper face of the flange 44 being formed with an annular groove to receive the O-ring seal 46, and it is formed at the upper free end thereof with a concave spherical end surface 48. The lower end of the inner tube 32 is machined to provide a conical or other valve seat 50 and a slot 52 formed across the free end for a purpose to be described. Obviously, the inner and outer tubes can, alternatively, be formed by machining the same from bar stock.

One of the main features of the nozzle 10 is the steel or other suitable wire 54 extending axially, with cylindrical clearance 56, through the passage through the inner tube 32, the wire having formed on, or secured to, the lower end thereof a valve member 58 having a conical valve portion 60 for engaging the seat 50, a collar portion 62 having a diameter providing a relatively close fit with the inner diameter of the outer tube 30 and a cylindrical free end portion 64 slidable in the smaller diameter opening 42 at the free end of the outer tube 30. It will be noted that a portion of the collar 62 is flattened on opposite sides 66 and received in a slot 52 formed in the free end of the inner tube 32, as shown in FIGURES 2 and 3.

The upper end of the wire 54 is provided with an enlarged threaded portion 68 flattened on opposite sides thereof, or at the end 70 thereof, the threaded portion being received in an internally threaded cylindrical anchor member 72 having a flange 74 with a convex spherical end engaging the upper concave spherical end 48 of the inner tube 32 and one or more openings 76 therein providing communication for a flow path into the inner tube 32.

The internally threaded passage 18 of the nozzle holder 12 has screwed therein an externally threaded fuel line fitting 78, the inner end of which bears on the flange 44 of the inner tube 32 so as to compress the O-ring 46 and provide a seal. At the same time, the fitting 78 forces the flange 44 down on a shim 80 positioned between the llange 44 of the inner tube and the flange 34 of the outer tube 30, the shim having a specific purpose to be described. The fuel litting 78 is, of course, provided with a chamber 82 adapted to receive, with clearance, the threaded upper 68 end of the wire 54 and the internally threaded anchor 72. A passage 84 communicates the chamber 82 with the outer free end of the fitting so that a fuel line 86 may be connected to the fitting in the usual manner, as shown in FIGUR-E 4. A lock nut 88 threaded on the fitting 78 and jammed against the nozzle holder 12 maintains the fitting secured to the nozzle.

Another structural detail to be noted is the locating pin 90 inserted through aligned openings or passages in the valve holder 12, the shim and the flanges 44 and 34 on the inner and outer tubes so as to retain these components in a definite predetermined relationship with respect to the engine 26.

Fuel flow passages 96 leading to the directional orifice 98 are formed in the lower end of the valve member downstream of the valve 60. In the case of the unsymmetrical orifice construction shown, providing a directional spray, the locating pin and the slot 52 in the end of the inner tube 32 receiving the flattened portion 66 of the collar 62 retain the essential components of the assembly 10 in a definite predetermined relation with respect to the engine to insure that the ffuel will be sprayed into the engine cylinder 100 in the proper direction, as shown by FIGURE 5', for example.

An O-ring seal 92 is provided between the inner and outer tubes near the bottom end of the nozzle, and a Teflon or other suitable seal 94 is provided or formed on the outer diameter of the outer tube 30 as a seal between the engine 26 and the nozzle assembly 10.

With the above construction, it will be seen that the nozzle 10 is assembled by inserting the threaded end 68 of the wire 54 from the notched end of the inner tube 32 until the llattened portion 66 of the collar 6-2 is received in the slot 52. The internally threaded anchor 72 may then be threaded on the threaded end 68 of the wire and tightened a predetermined number of turns, resulting in a predetermined uniform stress on the wire 54, thereby preloading the valve 60 on its seat 50. For this purpose, the anchor 72 extends above the nozzle holder 12. This subassembly may then be assembled into the outer tube 30 from the llanged end thereof, with the proper thickness shim 80 positioned between the flanges 34 and 44 to determine valve travel. The subassembly 28 may then be inserted through the nozzle holder 12 from the threaded end thereof, with the pin 90 in location. The assembly 10 is completed by threading the fitting 78 into the nozzle holder 12 to the required torque and tightening the jam nut 88.

Assembly on the engine is by inserting the lower end 28 of the nozzle through the clearance opening 102 formed in the engine and securing the same by means of the bolts 24. The fuel line 86 is then attached by means -of the usual fitting.

FIGURE 6 illustrates a somewhat simpler modification wherein the stress in the spring wire 54 connected to the valve is provided not by the threaded means shown by FIGURE 2, but by a horseshoe or other similarly shaped washer or spacer 104 which may be inser-ted between the flat end of the tube 32 and the abutment 106 formed by the enlarged free end of the wire 5'4. Spacers of preselected variable thickness may be used to vary the stress in the wire, and any suitable means may be formed on the free upper end of the wire for gripping and straining the same to permit insertion of the spacer '4. Otherwise, the nozzle construction may be the same as that shown by FIGURE 2.

Operation T he fuel line 86 is, of course, connected to any suitable fuel injection pump (not shown) which delivers a proper quantity of fuel to the nozzle un-der the required pressure for a predetermined duration and in timed relation to the operation of the engine cylinder 100. The purpose of the nozzle 10 is to spray this fuel into the cylinder, in the required direction in the case of the nonsymmetrical nozzle shown, for a precise period of time only and to prevent the spray or leakage of fuel at all other times.

Fuel under sutiicient pressure to unseat va'lve 60 by straining the wire 54 passes through the passage 84 and the chamber '82 in the fitting 78 and then through to the clearance between the wire 54 and the inner tube 32. The Oring 4'6 prevents leakage of fuel between the inner end of the fitting 78 and the flange 44 of the inner tube 32. There is a fluctuating force exerted lby the fuel tending to separate `the fitting 78 and the nozzle holder 12, but this force is exceeded by the static force of the preload in the threads between fitting 78 and holder 12. Thus, the fitting 78 and holder 12 are not subjected to fluctuating high fuel pressures, which may reach 10,000 p.s.\i., but only to the higher static preload force between the threads.

In the modification shown by FIGURE 6, the fuel passes from the chamber 82 t-o the clearance 56 between the wire and the inner tube through the opening 108 in the horseshoe-shaped spacer 104.

The fuel then travels through the efficient, straight cylindrical flow path comprising the clearance 56 between the wire 54 and the Iinner tube 32 t-o the valve 60, which is normally maintained in a closed position .by the stressed wire.

When the fuel pressure acting on the area of the valve 60 exceeds the force of the wire plus the force due to cylinder chamber compression pressure holding the valve closed, the valve 60 opens and fuel passes by the valve seat 50, into the passages 96 and into the cylinder 100 through the directional orifice 98.

When the pump pressure subsides, the stressed wire, which is never strained beyond its elastic limit, plus the pressure in cylinder chamber 100 closes the valve 60 until the cycle is repeated by the pump.

It has been stated that the initial preload of the valve `60 is determined either by the thickness of the spacer 1014 in FIGURE 6 or the number of turns applied to the threaded anchor member 72 in FIGURE 2. This is easily done within acceptable limits because the nozzle structure is such that engine combustion chamber pressure, which varies within wider limits, acts instantaneously on the collar `62 and the portion 6'4 in the valve closing direction.

kFor any particular nozzle design, the thickness of the shim '80 determines the stroke of the valve 60. To determine the shim thickness required on assembly, the wire 54 is pulled tight so that the valve 60 engages the seat `50; the wire and inner tube assembly is then forced downwardly through the outer tube 30 until the bottom of the collar 62 engages the stop 40. In this condition and with shim 80 omitted from the subassembly, the valve 60 is locked between the valve seat 50 and the stop 40 with no stroke. The .clearance between the flanges '34 and 44 lis then measured and a shim having a thickness exceeding this dimension by any desired valve stroke, .005" for example, is employed to give a stroke of .005. The selected stroke must be such that the attened portions 66 of ythe collar 62 never leave the slot 52 formed in the end of the inner tube 32.

The shoulder 40 formed on the end of the outer tube 30 not only provides a positive stop to limit the valve stroke, but, even more important, it prevents the valve 60 from being injected into the engine cylinder 100 in the event that the Wire 54 should fai-l. Should spring failure occur, the valve 60 will act as a constantly open valve, at least during the injection cycle with compression pressure acting as the valve preload force, and permit continued, although less eflcient, operation of that particular cylinder of a multi-cylinder engine.

It will be noted that the valve 60i is relatively small and that the only frictional drag involved is the comparatively smalll surface area between the collar 62 and the outer -tube 30. There are no other moving parts. This being so, the nozzle 10 is characterized by an overeal'l low moving mass, with consequent reduced impact stresses at the valve seat and stop. Furthermore, any such impact stresses tend to be further reduced by the comparatively large volume of materia-l comprising the length of the tubes, as determined by the specific engine design. It is preferable from this -standpoint that the tubes 30 and 32 should 'be as long as engine design will permit.

IDue to the low moving mass, the valve 60 opens and closes very quickly, providing a sharp cut-off. Cylindrical spray around the collar 62 is greatly reduce-d or eliminated by the tortuous (two turns) that leakage fuel must travel around the collar 62, which has a close fit with the outer tube 30, and any such leakage is rapidly cut off by the poppet seal provided by engagement of the collar 62 with the stop 40. Any such minimal leakage as may occur is not sufiicient to effect engine performance, but does tend to provide squish dampeniug of the valve 60.

The absence in this nozzle of commonly employed internal differential areas acted upon by fuel pressure elimin-ates internal leakage paths and the need for leakage return lines or passages.

`Cylindrical spray patterns are also eliminated by the high orifice to leakage path area ratio, insuring that the spray orifice 98 is the domineering orifice or llow path. This is so because, as stated above, the only leakage path is around the collar 62, this path being relatively small and promptly cut off by the poppet seal.

In the'nozzle shown, the outer diameter of the outer tube 30 may be on the order of .360", and it can, of course, be even smaller, depending upon engine fuel requirements. This feature, which is made possible `by the use of the uniform-stress valve preloading wire, instead of the prior art helical coil spring, is a distinct advantage in that the clearance dimension 102 required in the engine head in order to install the nozzle is on the order of .362", as illustrated in FIGURES 4 and 5, wherein the nozzle 10 embodying the invention is shown in solid lines and larger diameter prior art nozzles are shown in dotted lines 110. Obviously, the smaller nozzle space requirement gives engine designers additional freedom in design factors such as size and location of intake and exhaust valves 112 and 114, engine cooling cavities A116, etc.

It has been a practice in the past to provide cooling for nozzles to eliminate certain problems resulting from high nozzle temperatures. A nozzle embodying the invention, wherein the inner and outer tubes 32 and 30 may comprise high fatigue strength, medium carbon alloyed steel, thin-walled tubing with clearance therebetween, has a tendency to reduce conduction of engine heat to the nozzle for a reason of the small air space or clearance 118 between the inner and outer tubes. Furthermore, the comparatively large volume of fuel passing through the relatively small diameter inner tube provides significant cooling, .improving the operation and life of the nozzle and eliminating the need for any additional structure to provide cooling, which would necessarily increase nozzle diameter.

It should be apparent that the particular cross-sectional shape of the uniform-stress member 54 is not in any way limited to a round wire, and the more efficient uniformstress spring feature enables use of sufficient cross-sectional area to give a safety factor in the event of defects such as stress risers in the spring material.

Close fit design modifications of the concentric tube design can permit the outer tube to support any deflections of the inner tube, thereby reducing hoop stresses in the inner tube, and limited frictional drag between the tubes at the close fit portion 38 thereof provides additional damping of vibrations on valve seating and the end of the valve stroke.

It should be apparent from the above description that a nozzle embodying the invention fulfills the numerous objects and advantages previously stated and that the invention has been described in sufficient detail so as to enable anyone skilled in the art to practice the same. Modifications are possible within the scope of the invention; for example, if a symmetrical orifice design or a cylindrical spray pintle design, as opposed to the direction orifice 98, is desired, there is no need for the locating pin 90 and the inner tube slot 52 and fiattened sides 66. Accordingly, no limitations are intended, except as recited in the appended claims.

What we claim as our invention is:

1. An injection nozzle, comprising a body formed to provide a fluid inlet, a fiuid outlet, a passage connecting said inlet and said outlet, valve means controlling said outlet, said valve means comprising a valve member normally held against a cooperating valve seat carried by said body, and uniform-stress means connected at one end thereof to said valve member normally holding said valve member in a closed position, the other end of said uniform-stress means having self centering means anchoring the same on said body, said self-centering means minimizing eccentric loading of said uniform stress means and providing optimum sealing between said valve member and said cooperating valve seat, said uniform-stress means comprising a straight wire-like tension member, said tension member being preloaded to a predetermined stress sufficiently below its elastic limit so that opening of said valve member is affected by straining said tension member within its elastic limit.

2. An injection nozzle, comprising a body formed to provide a fluid inlet, a fiuid outlet and a passage connecting said inlet and said outlet, valve means controlling said outlet and uniform-stress means holding said valve means in a closed position, said uniform-stress means comprising a straight wire or other similar tension mem ber anchored at one end and secured to said valve means at the other end, said tension member being preloaded to a predetermined stress sufficiently below its elastic limit so that opening of said valve means is affected by straining the same in tension within its elastic limit, said tension member extending through said connecting passage with clearance therebetween providing a uid flow path, said connecting passage having a cross-sectional area greater than that of said tension member and having a valve seat therein engaged by said valve means, said connecting passage including stop means located on the side of said valve means opposite said seat for limiting valve stroke and preventing said valve from freely separating from said nozzle in the event of failure of said tension member, said valve means including a discharge therein, and said valve means and said stop are each formed with mating surfaces providing for a positive seal against flow of fluid around said valve means when said valve means is in the full open position against said stop.

3. An injection nozzle according to claim 2 wherein said valve means includes a relatively small area close fitting surface in sliding relationship to a containing surface of said body thereby providing a high discharge orifice-to-leakage path area ratio so that said discharge orifice is the domineering path.

4. An injection nozzle, comprising a body formed to provide a fluid inlet, a fluid outlet and a passage connecting said inlet and said outlet, valve means controlling said outlet and uniform-stress means holding said valve means in a closed position, said uniform-stress means comprising a straight wire or other similar tension member anchored at one end and secured to said valve means at the other end, said tension member being preloaded to a predetermined stress sufiiciently below its elastic limit so that opening of said valve means is affected by straining the same in tension within its elastic limit, said tension member extending through said connecting passage with clearance therebetween providing a fiuid flow path, said connecting passage having a crosssectional area greater than that of said tension member and having a valve seat therein engaged by said valve means, and a relatively close fit interface between said valve means and a chamber within said body containing said valve means defining the only leakage path around said valve means, said path including a plurality of changes in direction so as to reduce leakage therethrough.

5. An injection nozzle, comprising a body formed to provide a uid inlet, a uid outlet and a passage connecting said inlet and said outlet, valve means controlling said outlet and uniform-stress means holding said valve means in a closed position, said valve means having formed therein a nonsymmetrical discharge orifice, and means provided for maintaining said orifice in a predetermined positional relationship with said body.

6. An injection nozzle, comprising a body formed to provide a fluid inlet, a fluid outlet and a passage connecting said inlet and said outlet, valve means controlling said outlet and uniform-stress means holding said valve means in a closed position, said uniform-stress means comprising a straight wire or other similar tension member anchored at one end and secured to said valve means at the other end, said tension member being preloaded to a predetermined stress sufficiently below its elastic limit so that opening of said valve means is affected by straining the same in tension within its elastic limit, said body comprising a valve holder having a two diameter passage extending therethrough so as to provide a shoulder therein, the outer end of the larger diameter portion of said passage being threaded, a subassembly inserted into said valve holder through the end thereof having the larger diameter threaded opening, said subassembly comprising a first outer tubular member having an outer diameter substantially equal to that of the s maller diameter portion of said passage through said holder and a ange at one end thereof having a diameter substantially equal to the diameter of said larger diameter portion of said passage through said holder, said flange being seated on said shoulder, and a second inner tubular member positioned concentrically with clearance in said first outer tubular member, said second tubular member having a flange similar to the flange on said first tubular member, a washer type shim disposed between said flanges, the upper surface of said flange on said second tubular member having a circular groove with a seal disposed therein, said subassembly extending through the smaller diameter portion of said passage and beyond said holder, said inner tubular member having a valve seat formed at the end thereof opposite its flanged end, said outer tubular member extending beyond said seat and having a valve stop formed thereon, said valve means being slidable within said outer tubular member between said valve seat and said stop, a fitting threaded into said valve holder so that the end thereof compresses said seal in said ange of said inner tubular member, said tension member extending from said valve means through said inner tubular member and beyond the anged end thereof, self-centering threaded means for anchoring the end of said tension member opposite said valve means and for variably stressing the same, said fitting having a passage therethrough receiving said threaded means with clearance, openings in said threaded means communicating said passage in said fitting with said inner tubular member, a

9 10 seal between said inner and outer tubular members and 2,192,803 3/ 1940 Purdy et a1. 239-453 an exterior seal on said outer tubular member. 2,901,181 8/ 1959 Bek 239-533 X References Cited ALLEN N. KNOWLES, Primary Examiner. UNITED STATES PATENTS 5 M. Y. MAR, Assistant Examiner. 1,609,578 12/1926 Scott 239-453 1,740,316 12/1929 Ricardo. U'S- CL X-R- 1,755,192 4/1930 Scott 239--453 X 123-32

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