NOZZLE ASSEMBLY

Abstract: The invention relates to a nozzle assembly used to spray a liquid, for example oil, for cooling a reciprocating piston in an engine. Heretofore, the spray pattern has been undesir­ ably divergent and this has proven to be a problem when spraying a long distance. The present nozzle assembly (10) maintains a substantially columnar spray pattern by having an inlet portion (40) defining an opening (46), and an outlet portion (42) defining a first passage (62) for communicating a first liquid flow from the opening (46) outwardly thereof at a first velocity, and a plurality of passages (66) for communi­ cating a second liquid flow from the opening (46) outwardly thereof at a second velocity less than the first velocity.

Description: NOZZLE ASSEMBLY. This invention relates generally to a nozzle assembly for spraying a liquid in a substantially columnar form and, more particularly, to a nozzle assembly for spraying a stream of cooling liquid into a reciprocating piston passage. In using a nozzle to spray a liquid, the pattern of the stream leaving the nozzle is important to assure that the liquid is delivered to the precise location desired. For example, a nozzle is commonly used to spray a cooling liquid such as engine oil upwardly against the piston as it reciprocates in order to cool it. In longer stroke engines particularly, the oil must be sprayed a relatively long distance toward the piston when it is at its top dead center position. The pattern of the spray is therefore important so that the oil reaches the desired portion of the piston for direct cooling. The oil can then drip or be deflected downwardly to cool the remaining portion of the piston. Heretofore, the nozzles in such engines have utlized a single opening having a sufficiently large cross-sectional area to deliver the desired volume of oil for a given period of time. However, over the distances which the oil is directed, it tends to spread out or have an excessively wide spray pattern. This reduces the effectiveness of the cooling oil in that sufficient amounts do not reach the piston crown area One attempted experimental solution was to taper the outlet passageway in the nozzle to better concentrate the stream leaving the nozzle. However, the manifold construction and tapered nozzle imparted an undesirable rotation and turbulence to the oil particles so that an unacceptable diverging spray pattern still resulted. According to the present invention a nozzle assembly for spraying a liquid in a substantially columnar form comprises an outlet portion having a first passsage for passing a first flow of liquid to a first nozzle opening for ejection therethrough along a first axis at a first velocity; and a plurality of second passages for passing second flows of liquid to second openings along a plurality of paths generally encircling the first passage, the second flows each having a velocity less than the velocity of the first flow. Preferably the assembly includes an inlet portion separate from the outlet portion and having an opening therethrough, the axis of the opening being substantially aligned with the axis of the first passage in the outlet portion. One example of a nozzle assembly according to the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagrammaticelevationalview of an engine with a portion broken open and sectioned showing a nozzle assembly of the present invention for spraying a cooling liquid in columnar form into a passage in a piston of the engine; Figure 2 is a diagrammatic and greatly enlarged sectional view of the nozzle assembly of Figure 1; and, Figure 3 is a diagrammatic, outlet end part plan view of the nozzle assembly taken along line Ill-Ill of Figure 2. Referring to the drawings, and particularly to Fig. 1, a nozzle assembly 10 is shown associated with an internal combustion engine 12. The engine has a block 14 in which a cylinder liner 16 is carried. A piston 18 is positioned in the cylinder liner and reciprocates, as is known in the art, within the cylinder liner. The block 14 has a passageway 20, and a liquid distribution manifold 22 is releasably connected to the block in communication with the passageway. The nozzle assembly 10 receives a cooling liquid, such as engine oil, under pressure from the passageway and the manifold, which is then sprayed upwardly toward the piston as it reciprocates in a liquid column as is illustrated and identified by the letter "A". The piston 18 has a profiled downwardly facing and stepped opening 24 and a straight passage 26 connected to the opening which extends upwardly to an internal annular chamber 28 located at the crown area thereof. A plurality of generally radially extending passages 30 serve to communicate cooling liquid in the annular chamber with a centrally disposed cavity 32. From the cavity the liquid can descend by gravity through a central port 34 to the region of the connection between the connecting rod 36 and gudgeon pin 38 for lubrication thereof. As best seen in Fig. 2, the nozzle assembly 10 includes an inlet portion 40 and an outlet portion t2 releasably secured thereon. In the instant example the inlet portion is an integral outlet part of the manifold 22 and has a substantially cylindrical inner wall 44 at the outlet thereof defining an opening 46 through which the cooling liquid flows generally along a first central axis 48. The inlet portion further has external connecting threads 50 and an end face 52, and the outlet portion has internal connecting threads 54 and a pocket 56 for screwthreadably receiving the inlet portion. The outlet portion 42 of the nozzle assembly 10 includes a planar inner end face 58 and a planar outer end face 60 parallel thereto defining a preselected length "L" therebetween as is illustrated in Fig. 2. More specifically, a cylindrical outlet passage 62 having a preselected diameter "D1" is defined between the end faces and is disposed on a second central axis 64 generally aligned with the first central axis 48 of the inlet portion 40. Moreover, a plurality of cylindrical outlet passages 66 are also defined between the end faces and individually have a diameter "D2". The passages 66 are preferably aligned along a plurality of individual axes 68 which are parallel to the central axis 64 and symmetrically located a radial distance therefrom to establish a radial separation distance "S" between the central passage 62 and the surrounding passages 66 as is illustrated in Fig. 3. It is theorized that the minimal radial separation distance "S" should be about 1 mm, or one half the diameter "D2", whichever is greater. Thus, the central outlet passage 62 constitutes a primary or first passage means 70 for communicating a first liquid flow from the opening 46 through the outlet portion 42, and the encircling passages 66 constitute a secondary or second passage means 72 for communicating a second liquid flow from the opening 46 through the outlet portion. Advantageously, the first liquid flow has a flow rate along the central axis 64-at a first velocity, and the second liquid flow has a flow rate in the individual passages 66 at a second velocity less than the first velocity. The velocities of the individual outward liquid flow paths from the nozzle assembly 10 are at least in part based upon a relationship to the boundary layer flow conditions adjacent the inner wall 44 of the opening 46 in the inlet portion 40. As is known in the art, the boundary layer flow through a pipe, such as the manifold 22 might represent, is a region adjacent the wall of decreased liquid velocity owing to the viscous drag of the liquid thereat. In the nozzle assembly 10, the primary outlet passage 62 is spaced radially inwardly of the axial extension of the boundary layer within opening 46 in order to achieve the first desired velocity. Where the outlet passage is positioned centrally as shown, such first velocity will basically be the highest velocity through the inlet portion 40 and the highest velocity through the nozzle assembly. The reduced second velocity desired from the secondary outlet passages 66 is established in the instant embodiment by locating them at least in part in substantial axial alignment with the boundary layer flow along the inner wall 44. This can be accomplished by positioning the radially outermost portion of the secondary outlet passages 66 in axial alignment with the inner wall zz of the opening 30. In other words, the radially outer edges of the peripherally grouped outlet passages are constructed axially flush with the inner wall such that liquid at a decreased velocity will enter the secondary outlet passages: it should be understood that the nozzle assembly 10, and particularly the outlet passages 62,6S can be of other configurations without departing from the invention. For example, the outlet passages can be formed of individual tubes, not shown, attached to the inlet portion 40. Also, the shape, orientation, number and size of the outlet passages can be varied as long as the cross-section thereof is basically symmetrical to assure columnar flow. For another example, a plurality of arcuately shaped outlet passages, not shown, can be formed in an annular relationship about the primary outlet passage. However, it is believed that the illustrated configuration represents the most desirable and economical nozzle assembly contemplated. In use, the nozzle assembly 10 sprays a substantially columnar stream pattern "A" upwardly into the profiled opening 24 and the passage 26 formed in the reciprocating piston 18. Whereupon the oil enters the annular chamber 28 substantially at the same flow rate as it had leaving the nozzle assembly. In other words, the oil stream makes substantially no contact with the walls of the opening 24 so that there is no loss of cooling oil before the stream enters the interior of the passage 26. When the piston is at bottom dead center as is indicated by the phantom line in Fig. 1, the outlet portion 42 of the nozzle assembly is received in the profiled opening 24 in the piston with but a minimum of clearance. But when it is at top dead center as shown, the stream is delivered for the greatest distance in columnar form directly into the passage 26. It has been found that the use of multiple elongate passages 66 encircling the elongate central passage 62 greatly reduces any rotational turbulence of the oil in the inlet portion 40 of the manifold 22. This is in part due to the relatively significant ratio of the length "L" of the outlet passages 62,66 to the cross-section areas thereof as represented by the respective diameters D1 and D2. It is theorized 2 that the L/D ratio for the central passage 62 should preferably be in a range of from about 3.75 to about 6.0. Similarly, the L/D ratio for the outer passages 66 should preferably be in a range of from about 7.5 to about 13.0. It is further theorized that these two L/D ratios are related and should preferably not be less than 2:1 or greater than 3:1, and with the minimum individual ratio being above about 3.75. In one preferred embodiment the distance "L" was 15 mm, D1 was 2.5 mm, D2 was 1.15 mm, and the radial distance "S" between the central passage and the eight peripherically located passages was 1 mm. A sufficient quantity of oil must be available within a preselected pressure range above a minimum value of about 140 KPa in the inlet manifold 22. For example, in one instance oil under a pressure of about 480 KPa was available in the manifold sufficient for the subject nozzle assembly 10 to desirably supply about 18 litres/minute to the piston passage 26. Even though the oil in the manifold was in a fluid vortex state at the inlet portion 40 of the nozzle assembly, the plurality of relatively long straight passages 62,66 served to divide the swirling flow into a plurality of individual and straightened streams. Due to the viscosity of the air medium between the central stream and the plurality of encircling streams traveling at a lesser velocity than the central stream, the outlying streams have a tendency to be pulled radially inwardly toward the central axis 64 through a suction phenomena aided by atmospheric pressure, all of which factors maintain the liquid stream pattern 'A" in columnar form for a substantially significant overall distance, for example about 400 mm. It is also to be noted that space is at a, premium in the interior of an engine, so that it was desired to maintain the overall length "E" of the outlet portion 42 in Fig. 2 to below 25 mm in order to assure sufficient operating clearance from the piston 18. Thus it is apparent that the nozzle assembly of the present invention is relatively compact and simple in operation, and can advantageously direct a columnar stream of oil into a linear passage in a reciprocating piston so that it can cool the crown portion thereof. This is accomplished without resorting to a complicated series of pressurized'oil passages through the crankshaft and connecting rod, which costly alternative also tends to weaken these components in relatively critical areas.

Claims: CLAIMS 1. A nozzle assembly (10) for spraying a liquid in a substantially columnar form, comprising an outlet portion (42) having a first passage (62) for passing a first flow of liquid to a first nozzle opening for ejection therethrough along a first axis (64) at a first velocity; and a plurality of second passages (66) for passing secondflowsof liquid to second openings along a plurality of paths generally encircling the first passage (62), the second flows each having a velocity less than the velocity of the first flow. 2. A nozzle assembly (10) according to claim 1 wherein the second passages (66) are straight. 3. A nozzle assembly (10) according to claim 2 wherein the second passages (66) are parallel to the first axis (64). 4. A nozzle assembly to any of claims 1 to 3, further including an inlet portion (40) separate from the outlet portion and having an opening (46) therethrough, the axis (48) of the opening being substantially aligned with the axis (64) of the first passage (62) in the outlet portion. 5. A nozzle assembly (10) according to claim 4, wherein the opening (46) is defined by a cylindrical inner wall (44) and wherein the second passages (66) are arranged in an annular manner around the axis (64) of the first passage (62) to receive liquid flow axially from the opening (46) adjacent the wall (44) thereof. 6. A nozzle assembly (10) according to any of claims 1 to 5, wherein the outlet portion (42) has inlet and outlet end faces (58, 60) oriented normal to the first axis (64) and the passages (62, 66) extend between the end faces (58, 60). 7. A nozzle assembly (10) according to claim 4, wherein the inlet and outlet portions (40, 42) are screw threadably connected. 8. A nozzle assembly (10) according to any of claims 1 to 7, wherein the passages (62, 66) have a preselected length L, the first passage (62) has a preselected diameter D1, the secondary passages (66) have a preselected diameter D2, and the first ratio of LID1 and second ratio LID2 fall within preselected first and second ranges respectively above about 3.75. 9. A nozzle assembly (10) according to claim 8, wherein the first ratio of L/D1 falls within a range of about 3.75 to about 6.0, and the second ratio of L/D2 falls within a range of about 7.5 to about 13.0. 10. An engine having a reciprocating piston having a chamber (28) adjacent its head and a straight passage (26) connecting with the chamber and aligned substantially with the first axis (64) of a nozzle assembly according to any of claims 1 to 8, for spraying the cooling liquid therefrom in a substantially columnar form into the passage (26) and thus to the upper chamber (28) of the piston (18).

Inventors: CLAIRMONT, FLOYD H., JR., GRAZE, RUSSELL R., JR.
Applicants: CATERPILLAR TRACTOR CO.
Application year: 1981
Main classification: B05B1
IPC codes: E04B1, E04B2, F01P3, B05B1