WO2003048541A1 - Moteur a carter sec - Google Patents

Moteur a carter sec Download PDF

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Publication number
WO2003048541A1
WO2003048541A1 PCT/US2002/039214 US0239214W WO03048541A1 WO 2003048541 A1 WO2003048541 A1 WO 2003048541A1 US 0239214 W US0239214 W US 0239214W WO 03048541 A1 WO03048541 A1 WO 03048541A1
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WO
WIPO (PCT)
Prior art keywords
oil
piston
cylinder
port
seal
Prior art date
Application number
PCT/US2002/039214
Other languages
English (en)
Inventor
Nicholas S. Hare
Original Assignee
Hare Nicholas S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/266,728 external-priority patent/US6644263B2/en
Application filed by Hare Nicholas S filed Critical Hare Nicholas S
Priority to AU2002351306A priority Critical patent/AU2002351306A1/en
Publication of WO2003048541A1 publication Critical patent/WO2003048541A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
    • F01M11/02—Arrangements of lubricant conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/06—Lubricating systems characterised by the provision therein of crankshafts or connecting rods with lubricant passageways, e.g. bores
    • F01M2001/062—Crankshaft with passageways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/06—Lubricating systems characterised by the provision therein of crankshafts or connecting rods with lubricant passageways, e.g. bores
    • F01M2001/064—Camshaft with passageways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/06—Lubricating systems characterised by the provision therein of crankshafts or connecting rods with lubricant passageways, e.g. bores
    • F01M2001/066—Connecting rod with passageways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/08—Lubricating systems characterised by the provision therein of lubricant jetting means
    • F01M2001/083—Lubricating systems characterised by the provision therein of lubricant jetting means for lubricating cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/08—Lubricating systems characterised by the provision therein of lubricant jetting means
    • F01M2001/086—Lubricating systems characterised by the provision therein of lubricant jetting means for lubricating gudgeon pins
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M1/00—Pressure lubrication
    • F01M1/12—Closed-circuit lubricating systems not provided for in groups F01M1/02 - F01M1/10
    • F01M2001/126—Dry-sumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
    • F01M11/02—Arrangements of lubricant conduits
    • F01M2011/026—Arrangements of lubricant conduits for lubricating crankshaft bearings

Definitions

  • the present invention relates generally to internal combustion engines, and particularly to two-stroke and four-stroke engines having an improved lubrication system capable of reducing polluting emissions.
  • the present invention recognizes the global need for reduced hydrocarbon emissions from small power-producing engines, especially as relates to the rapidly growing demand for agricultural and light industrial power in developing economies. In these economies, the low weight and low cost of two-stroke engines will be difficult to ignore, and it may be expected that two-stroke engines will be widely used. Two-stroke engines produce high levels of unbumed hydrocarbon emissions, since, due to their operating principle, exhaust gases are expelled from the engine's cylinder at the same time that a fresh fuel/air charge is brought in, leading inevitably to mixing between the two and the inadvertent expulsion of unburned charge with the exhaust gases.
  • two-stroke engines pass their fuel/air charge through the crankcase to allow a slight pressurization of the charge, caused by the descent of the piston, to assist the flow of charge into the cylinder.
  • the charge entrains lubricating oil droplets, which are splashed on the crankshaft main bearing and connection rod (crank) bearing and sprayed on the cylinder walls and wrist pin.
  • oil is mixed with the fresh charge before entering the crankcase, in which case the charge is used as an agent for transporting oil to the engine surfaces requiring lubrication.
  • Lubricating oil entrained in the charge is inducted into the cylinder, where it either flows through into the exhaust, creating more unburned hydrocarbon emission, or remains in the cylinder where it is burned, creating a more noxious set of pollutants than would stem from the combustion of the engine fuel itself.
  • the present invention retains the engine size advantage of the two-stroke engine, the cost advantage of the carbureted two-stroke engine and reduces its unburned hydrocarbon emissions and lubricating oil combustion characteristics to levels comparable with the most advanced direct injected, two-stroke, dry-sump engines. This is accomplished with a relatively minor increase in cost for the inclusion of new parts and new machined or cast features on conventional parts. These, parts and features provide an improved two-stroke, spark-ignited engine capable of operating with very little unburned fuel emission and with very little lubricating oil combustion.
  • the present invention is also applicable to four-stroke spark-ignition engines and compression-ignition engines such as diesel engines.
  • the piston is provided with upper and lower seals defining an annular oil chamber in cooperation with the body of the piston and an adjacent portion of the cylinder wall as the piston is reciprocated within the cylinder. If necessary, an oil sleeve may be added between the cylinder and crankcase to effectively extend the cylinder wall to ensure that an annular oil chamber is defined along the desired length of the piston's stroke.
  • the lower seal substantially prevents any oil within the annular oil chamber from flowing into the crankcase.
  • a small, controlled amount of oil is allowed to escape past the upper seal, into the upper portion of the cylinder, in order to lubricate the compression rings and then be consumed, as is normal practice in engine design.
  • the remainder of the oil is circulated through the annular oil chamber to lubricate the cylinder, piston, compression and/or oil control rings, and/or seals.
  • the annular oil chamber may also lubricate the wrist pin.
  • oil conduits or passages in the body of the piston may connect the wrist pin area with the oil chamber.
  • a system of sealed passages or conduits leading to and/or from the annular oil chamber may be provided to lubricate bearings in the crankcase. Oil from a reservoir is circulated through the annular oil chamber and/or the conduits by a pump. Because the oil reservoir is segregated from the crankcase by seals, the crankcase remains dry.
  • the invention concerns an internal combustion engine having a piston reciprocable within a bore of a cylinder.
  • the piston is pivotally connected to a crankshaft by a piston rod having at one end a wrist pin engaging the piston and at an opposite end a crank bearing engaging a throw of the crankshaft.
  • the crankshaft is rotatably mounted on a main bearing within a crankcase positioned beneath the cylinder bore.
  • a first seal is mounted on and circumferentially around the piston to define an upper end of the annular oil chamber.
  • the first seal has an outer circumference engaging the cylinder to limit any oil flowing from the annular oil chamber to the cylinder bore for lubricating the cylinder.
  • a second seal is mounted on and circumferentially around the piston to define a lower end of the annular oil chamber.
  • the second seal has an outer circumference engaging the cylinder to substantially prevent any oil within said annular oil chamber from flowing into the crankcase.
  • oil is either broadcast as a spray throughout the crankcase or inducted as a mist with the charge air.
  • the lubrication points are serviced by filling the entire crankcase with oil droplets. Many of these are inevitably inducted into the cylinder.
  • oil is selectively distributed to surfaces where it is needed for lubrication, and oil droplets do not enter the charge air stream. Therefore, lubricating oil consumption is limited to small amounts spread on the cylinder walls and seeping through the piston ring gaps, as is typical of a four-stroke engine.
  • the lubrication system of the invention greatly reduces the excessive oil combustion and unburned emission of conventional two-stroke engines (especially at idle speeds), which has reduced two-stroke acceptance on environmental grounds.
  • the invention's lubrication system makes the task of premixing oil and fuel unnecessary and avoids the loss of lubricating potential attendant to dilution with fuel. Employment of the invention should lead to a reduction in lubricating oil consumption, thereby lowering the operating cost of such engines.
  • the lubricating system also reduces spark plug fouling and combustion chamber carbon deposits, because very little lubricating oil is burned in the cylinder.
  • the present invention may be combined with features, including: (1) separate scavenging and charging air flows; (2) a throttleable charging air flow; (3) a port opening sequence wherein the exhaust port opens, followed by the scavenging port opening, followed by a charging port opening; and (4) variable exhaust port timing; as disclosed in commonly owned U.S. Patent No. 6,397,795, the entire disclosure of which is hereby incorporated herein by reference. BRIEF DESCRIPTION OF THE DRAWINGS
  • Figure 1 is an external perspective view of an engine according to the invention
  • Figure 2 is a sectional view taken along lines 2-2 of Figure 1 , showing the piston at the top of its stroke;
  • Figure 3 is a sectional view taken along lines 3-3 of Figure 1 , showing the piston at the bottom of its stroke;
  • Figure 4 is a sectional view taken along lines 4-4 of Figure 1 ;
  • Figure 5 is a partial cut-away view of the engine of Figure 1 ;
  • Figure 5A is an exploded view of an exemplary embodiment of the piston rod of Figures 1-5;
  • Figure 5B is an exploded view of an alternative embodiment of the piston rod of Figure 5A;
  • Figure 6 is a partial cut-away view of a portion of an exemplary four-stroke engine according to an alternative embodiment of the present invention.
  • Figure 7 is a partial cut-away view of a portion of an exemplary two-stroke engine according to another alternative embodiment of the present invention.
  • Figure 7A is an exploded view of an exemplary embodiment of a piston rod usable with the engine of Figure 7;
  • Figure 8 is a partial cut-away view of a portion of an exemplary four-stroke engines according to yet another alternative embodiment of the present invention.
  • Figure 9 is a partial cut-away view of a portion of an exemplary four-stroke engines according to yet another alternative embodiment of the present invention.
  • Figure 10 is a sectional view of an exemplary two-stroke engine according to yet another alternative embodiment of the present invention, showing separated scavenging and charging air flows;
  • Figure 11 is a sectional view of an exemplary four-stroke engine according to yet another alternative embodiment of the present invention, showing a transfer tube for inexpensive supercharging;
  • Figure 12 is a partial sectional view of the four-stroke engine of Figure 11 ;
  • Figure 13 is a sectional view of an exemplary four-stroke engine according to yet another alternative embodiment of the present invention.
  • Figure 14 is a partial sectional view of the four-stroke engine of Figure 13;
  • Figures 15A-15E are simplified schematic drawings illustrating valve operation in the four-stroke engines of Figures 1 1-12 and 13-14.
  • Figures 1-5 illustrate an exemplary embodiment of the present invention, namely a single-cylinder, single main bearing, two-stroke, spark- ignited, over-square (bore to stroke ratio 2.38) engine of about 126 cubic centimeters gas displacement.
  • the present invention has useful application in all other two-stroke and four-stroke, spark-ignition and compression-ignition engines.
  • the invention provides a traveling annular oil chamber allowing for a dry-sump lubrication system for two- or four-stroke engines, which is particularly useful for hand-held power tools and aircraft engines.
  • FIG. 1 Shown in Figure 1 is an external view of an engine 20 according to the invention.
  • engine 20 comprises a cylinder 22 in which a spark plug 24 is mounted. Also shown is an exhaust port 38 in cylinder 22, a charging tube 42 and a fuel metering device 44. While the fuel metering device 44 preferably uses a carburetor, it may also use an injector unit or a manifold fuel injection system to provide more precise control, though at greater expense. If it is found that the short duration of the fuel event does not allow for adequate atomization, then a modified carburetor design for providing adequate atomization may be employed. Alternatively, magnetic or electromagnetic-induced vibration of the fuel jet, the fuel stream itself, a screen in the fuel intake tube, etc., may be used to provide adequate fuel atomization.
  • Charging tube 42 connects the crankcase to the fuel metering device 44 that supplies fuel to the cylinder 22 during engine operation.
  • the charging port is oriented so as to direct the charge towards the spark plug 24 to develop a stratified fuel air mixture within the cylinder with a relatively rich fuel-air mixture positioned in the immediate vicinity of the spark plug, as disclosed in U.S. Patent No. 6,397,795.
  • the fuel/air charge may be mixed by swirling as it enters the combustion chamber or as it passes over contoured fins in the charging tube for swirling the charge.
  • cylinder 22 has a bore 46 receiving a piston 48 capable of reciprocal motion within the cylinder bore 46.
  • Cylinder bore 46 is sized to form an annular space 82 between the cylinder 22 and the piston 48.
  • Piston 48 is connected to a throw 50 of a crankshaft 52 by a piston rod 54.
  • Piston rod 54 is pivotally connected at one end to the piston 48 by means of a wrist pin 56, and at an opposite end to the throw 50 of the crankshaft 52 by a crankshaft bearing 58.
  • Crankshaft 52 is mounted on main bearing 60 in crankcase 28. It is understood that all bearings may be provided with oil seals that prevent oil from leaking from the bearings.
  • One-way valves 64 (only one being shown), preferably in the form of reed valves, are mounted in the crankcase 28 to allow ambient air to enter and replace the air that flows to the cylinder 22.
  • the crankcase 28 has a further opening 66 that allows air from the crankcase 28 to flow into the charging tube 42 via the reed valve 64.
  • a charging (intake) port 80 in cylinder 22 is connected to the fuel metering device 44 to allow a fuel-air charge to enter the cylinder bore 46 during engine operation.
  • An oil reservoir 30 holds lubricating oil. Associated with the oil reservoir 30 are an oil filter 32, an oil distribution manifold 34 and oil lines 36 (see Figure 1) connecting the manifold 34 with the cylinder 22.
  • the oil reservoir 30 is mounted on, but segregated from, the crankcase 28 and is in fluid communication with main bearing 60.
  • seals 86 and 88 are provided on the piston 48 to define an annular oil chamber 84 as a portion of the annular space 82 between the cylinder 22, piston 48 and seals 86, 88. The seals 86, 88 keep the oil within the annular oil chamber 84.
  • Annular oil chamber 84 provides lubricating oil to the piston 48, cylinder 22, and wrist pin 56.
  • oil circulated through the annular oil chamber 84 may travel through conduits to the crank bearing 58 and the main bearing 60 as described below.
  • the first seal 86 is mounted on and circumferentially around the piston 48 between the piston 48 and the cylinder 22 to define an upper end of the annular oil chamber 84.
  • the first seal 86 may be positioned in a groove extending around the piston 48, much like similar grooves used for conventional compression rings.
  • the first seal 86 has an outer circumference engaging the cylinder 22 to limit any oil flowing from the annular oil chamber 84 to the cylinder bore 46.
  • the first seal 86 is mounted on the piston 48 to be below the charging/intake and exhaust ports 80 and 38, respectively, when the piston 48 is at a top of its stroke (top-dead-center) within the cylinder bore 46, as best shown in Figure 2.
  • the first seal 86 is typically provided in addition to any conventional compression and/or oil control rings 100 so that the first seal 86 may be positioned below the intake and exhaust ports 80, 38 to prevent oil from escaping into the ports.
  • the first seal 86 may be constructed according to conventional oil ring practice to permit a controlled amount of oil to pass from the annular oil chamber 84 into an upper portion of the cylinder 22 to lubricate the cylinder 22, piston 48 and compression rings 100 as it traverses the cylinder 22, as is generally known in the art for conventional compression and/or oil control rings.
  • oil may be held in scoring or cross-hatching of the cylinder 22, as is generally known in the art.
  • the first seal 86 may be a sealing ring, substantially blocking oil flow thereby.
  • the second seal 88 is mounted on and circumferentially around the piston 48 between the piston 48 and the cylinder 22 and between the first seal 86 and the crankcase 28, to define a lower end of the annular oil chamber 84.
  • the second seal 88 may be positioned in a grove of the piston as described above for the first seal 86.
  • the second seal 88 is mounted on the piston 48 to be in contact with the cylinder 22 when the piston 48 is at a bottom of its stroke (bottom-dead-center) within the cylinder bore 46 as best shown in Figures 3.
  • the cylinder 22 may need to be extended toward the crankcase 28, relative to a conventional cylinder, to lengthen the cylinder wall.
  • an oil sleeve may be provided between the cylinder and the crankcase to effectively lengthen the cylinder wall, as described in detail in U.S. Patent No. 6,397,795.
  • the oil sleeve has a bore therethrough coaxially aligned with the cylinder bore and sized to receive the piston.
  • the piston is therefore reciprocable within the oil sleeve and cylinder bore and the annular oil chamber is defined between the piston and the oil sleeve and/or the cylinder.
  • the term "cylinder" refers to a cylinder and/or an oil sleeve.
  • the second oil seal 88 differs from a typical oil control ring in that it substantially prevents oil flow from the annular oil chamber 84 to the crankcase 28, thus, keeping the crankcase 28 free of lubricating oil and ensuring a dry sump, even with two-stroke engines.
  • an oil control ring may be used such that the ends of the oil control ring are tapered, beveled and/or overlapped to substantially close the usual gap between piston ring ends.
  • the second seal 88 prevents a substantial amount of oil from flowing into the crankcase 28.
  • the first and second seals 86, 88 therefore are fixed to and reciprocate with the piston 48, thus forming a traveling annular oil chamber 84 that lubricates the cylinder 22, piston 48, compression and/or oil control rings 100, and/or seals 86, 88.
  • the first and second seals 86 and 88 may be constructed of sintered bronze. Seals of other materials, such as graphite compounds or elastomerics such as rubber, are also suitable. Alternatively, such seals may be constructed of long-wearing, heat resistant polymers, such as Teflon, Kevlar, and Viton. The choice of seal material and design will largely depend upon the particular engine, its displacement, expected duty (light or heavy), cost, maintenance requirements and design life expectancy.
  • the rings may be constructed to have beveled, overlying ends so as to be self-sealing, as well known in the art.
  • the rings may be constructed as 0- rings having generally square cross-sections and concave sides so as to enhance sealing action.
  • a wick-like ring 89 (shown only in Figure 3), e.g. a ring of relatively porous or absorbent material, such as sintered bronze, is provided adjacent the compression and/or oil control rings 100 to better pick up oil deposited on a lower portion of the cylinder and carry it to upper portions of the cylinder that are not reached by the annular oil chamber 84.
  • any seals added in accordance with the present invention need not increase friction between the cylinder and piston by a substantial amount. This is due to the materials that may be used for the seals, and the need for relatively little pressure of the seals against the cylinder, which results from the fact that most of the heat and pressure due to combustion in the combustion chamber will be borne by the conventional compression rings. Any seals added in accordance with the present invention need withstand primarily the relatively low forces associated with the oil pressure.
  • An oil pump 92 preferably positioned within the oil reservoir 30, is driven by rotation of the crankshaft 52, e.g. by gearing thereto as known in the art, to pressurize oil 31 from the oil reservoir 30 and circulate it through the annular oil chamber 84 to lubricate the cylinder 22, piston 48, compression and/or oil control rings 100, and/or seals 86, 88.
  • the first seal 86 is mounted above the wrist pin 56 and the second seal 88 is mounted below the wrist pin 56, as shown in the embodiment of Figures 1-5.
  • at least a portion of any oil 31 in the annular oil chamber 84 also lubricates the wrist pin 56.
  • lubricating oil 31 is supplied from the oil reservoir 30 and drawn through an oil duct (not shown) to the oil distribution manifold 34, which directs the oil 31 through an oil filter 32 and then to oil lines 36 (see Figure 1) connecting the oil filter 32 to the cylinder 22.
  • Oil lines 36 are in fluid communication with the annular oil chamber 84 though oil ports 90, as shown in Figure 4.
  • the oil ports 90 are positioned in the cylinder 22 immediately below the position of the first seal 86 when the piston 48 is at the bottom of its stroke. In this location, oil ports 90 should never be passed by the second seal 88 throughout the entire range of motion of piston 48. This ensures that no oil will enter the crankcase 28 and contaminate the air therein and/or the intake and exhaust ports 80, 38.
  • An engine according to the present invention is operated to generate power in substantially the traditional manner, except for the lubrication system, as discussed further below.
  • oil supplied to the annular oil chamber 84 is contained between the piston 48 and cylinder 22 by the first seal 86 and second seal 88, both of which move with the piston 48.
  • the first and second seals 86, 88 move with the piston 48 and cooperate with the piston 48 and cylinder 22 to define a traveling annular oil chamber 84 that is supplied by oil pump 92 with oil 31 drawn from the reservoir 30.
  • the oil is circulated through the oil distribution manifold 34, through the oil filter 32, through the oil lines 36, through the oil ports 90 and into the annular oil chamber 84.
  • the traveling annular oil chamber 84 provides lubricating oil 31 to the surface of the cylinder 22 over which it passes, depositing oil thereon which is held in scoring and/or cross-hatching in the cylinder wall, as in known in the art.
  • Oil held therein is carried to upper portions of the cylinder. More specifically, oil deposited on the cylinder 22 by the oil chamber 84 during an upstroke of the piston is picked up by the compression, oil control or compression rings 100 during a downstroke, which rings then carry the oil to upper portions of the cylinder during the next upstroke. Accordingly, the compression rings, etc. 100 can carry oil to portions of the cylinder 22 that are never reached by the oil chamber 84. This is particularly important in two-stroke engines to carry oil to portions of the cylinder 22 above the intake and exhaust ports.
  • pressurized oil from the annular oil chamber 84 flows through port 90 into an oil groove 102 in the wrist pin 56 exposed to the annular oil chamber 84.
  • This oil flow lubricates the wrist pin bearing 104 (see Figure 4) connecting the piston rod 54 to the wrist pin 56.
  • Oil from the groove 102 collects in a central groove 106 around the wrist pin 56.
  • the central groove 106 communicates with a passage 108, extending along and through substantially the center of the piston rod 54.
  • a pair of piston rod seals 1 10 help contain the oil within the wrist pin bearing 104.
  • the piston rod 54 may be constructed of two mated portions 107a and 107b with facing grooves 108a and 108b to form the passage 108 on assembly.
  • the piston rod 54 may be made from a single piece having a groove 108 with a light cover 111 fixed along its length to close the open side of such a groove to form the passage.
  • the cover may be a piece of sheeting, such as sheet metal or foil plastic film, etc., tightly wrapped around the piston rod 54 to make the groove 108 an oil-tight conduit.
  • Lubricating oil passes from the piston rod oil passage 108 to the piston rod crank bearing 58. Oil is contained within the crank bearing 58 by crank bearing oil seal 112 (see Figure 5), so that oil does not seep into the crankcase 28.
  • crankshaft oil passage 116 communicates with a crankshaft sleeve circumferential passage 120 cut around the inside of one end of the crankshaft sleeve 122. Oil passes along the crankshaft sleeve 122 through four crankshaft sleeve axial oil passages 124, and exits the crankshaft sleeve 122 through four crankshaft sleeve radial oil passages 125.
  • the crankshaft sleeve radial oil passages 125 are separated from the crankcase 28 by the crankcase sleeve oil seal 126, so that oil does not seep into the crankcase 28.
  • oil may be circulated in an opposite direction.
  • FIG. 6 An exemplary four-stroke engine in accordance with the present invention is shown in Figure 6.
  • a single ring may act as both the first seal 86 and a compression and/or oil control ring 100, as discussed further below.
  • a compression and/or oil control ring 100 may be used as the first seal 86, and only the lower, second seal 88 is added to provide the annular oil chamber 84 according to the present invention.
  • oil is supplied to the cylinder 22 via an oil port 90a positioned in the cylinder 22 immediately below the position of the first seal 86 when the piston 48 is at the bottom of its stroke. In this location, oil port 90a should never be passed by the second seal 88 throughout the entire range of motion of piston 48.
  • the alternative engine embodiment of Figure 6 includes an oil port 90b provided on wrist pin 56 in fluid communication with wrist pin groove 102, central groove 106, piston rod passage 108, crank throw undercut 114, crankshaft passage 1 16, crankshaft sleeve circumferential passage 120 and crankshaft sleeve axial and radial passages 124, 125. Because these passages are all in fluid communication with each other they may be considered to be a single conduit that allows oil to flow from the annular oil chamber 84 back to the oil reservoir 30 while lubricating the various engine components, generally as described above with reference to Figure 5.
  • the return oil conduit of Figure 6 does not provide oil to the main bearing 60. Rather, the main bearing 60 is positioned within or otherwise in direct fluid communication with the oil reservoir 30 and is lubricated by any oil therein. More specifically, oil exiting the crankshaft sleeve radial oil passage(s) returns to the oil reservoir 30, the main bearing 60 being positioned within or in fluid communication with the oil reservoir 30 and being lubricated by any oil 31 therein by direct contact and/or immersion therein. As in
  • oil is carried by the annular oil chamber 84 for lubrication, as described above with reference to Figures 1 -5. As shown in Figure 6, oil travels around the annular oil chamber 84 and exits the annular oil chamber 84 through port 90b and along groove 102b, as generally described above.
  • Figure 7 shows an alternative embodiment of a two-stoke engine.
  • oil ports in the cylinder 22 are eliminated.
  • the oil ports 90a, 90b are positioned in or through the piston 48, e.g. through the wrist pin 56.
  • the embodiment shown in Figure 7 provides supply and return of oil via passages in the wrist pin 56, piston rod 54, crankshaft 52, etc. as discussed above with reference to Figure 5.
  • the piston rod 54 includes two separate passages 108, 109, as shown in Figure 7A, and the conduit from the annular oil chamber 84 for returning oil to the oil reservoir 30 in Figures 1-6 is essentially duplicated to provide an additional conduit for supplying oil from the oil reservoir 30 to the annular oil chamber 84.
  • the piston rod 54 may be constructed of two mating portions 107a and 107b, as shown in Figure 7A, or from a single piece having a groove 108c with a light cover 111 , similar to that shown in Figure 5B.
  • the seals 86, 88 are provided as discussed above with reference to Figures 1 -5.
  • the main bearing 60 is lubricated as discussed above with reference to Figure 6.
  • Lubricating oil 31 is supplied from the oil reservoir 30 and is pressurized by pump 92 and forced into the crankshaft sleeve through four crankshaft sleeve radial oil supply passages that are separated from the crankcase 28 by the crankcase sleeve oil supply seal, so that oil does not seep into the crankcase 28 (see corresponding structures in Figure 5).
  • oil passes along the crankshaft sleeve through four crankshaft sleeve axial oil supply passages.
  • Oil passes along the crankshaft sleeve circumferential supply passage cut around the inside of one end of the crankshaft sleeve.
  • the crankshaft supply passage communicates with the crankshaft oil supply passage.
  • the crankshaft oil supply passage is drilled through the crankshaft counterweight. Oil passes from the crankshaft oil supply passage to a circumferential crank throw undercut which passes oil to the crank bearing 58. Oil then passes from the crank bearing 58 along the supply piston rod oil passage 109, to a central groove 106 around the wrist pin 56 and to a groove 102a in the wrist pin 56, to lubricate the wrist pin bearing 104, and to flow through port 90a into the annular oil chamber 84.
  • crankshaft oil supply passage crankshaft sleeve circumferential supply passage and crankshaft sleeve, crankshaft sleeve axial oil supply passages, and crankshaft sleeve radial oil supply passages are all in fluid communication with each other they may be considered to be a single conduit or passage that allows oil to flow to the annular oil chamber 84 from the oil reservoir 30 while lubricating the various engine components.
  • An oil filter may be positioned along either the supply or return conduits.
  • Oil is carried by the annular oil chamber 84 for lubrication, as described above.
  • the oil travels around the annular oil chamber 84 and exits the annular oil chamber 84 through port 90b and along groove 102b, as generally described above with reference to Figures 1-5 and 6.
  • oil exiting the crankshaft axial oil passage(s) 124 returns to the oil reservoir 30 through passage 108 in piston rod 54, the main bearing 60 being positioned within or in fluid communication with the oil reservoir 30 and being lubricated by any oil 31 therein by direct contact and/or immersion therein.
  • Figure 8 shows an embodiment similar to that of Figure 7, but adapted to a four- stoke engine. Accordingly, one of the compression rings 100 is used as the first seal 86, as discussed above with reference to Figure 6. Operation of the engine and lubrication system occurs generally as described above with reference to Figures 6 and 7.
  • FIG. 9 An alternative embodiment of a four-stroke engine is shown in Figure 9.
  • oil is supplied to the annular oil chamber 84 as described above with reference to the embodiments of Figures 1-5 and 6.
  • an oil return port 90b is provided in the cylinder 22.
  • the oil return port 90b is in fluid communication with annular oil chamber 84 and oil return line 36a.
  • oil return port 90b in the cylinder 22 is positioned in the cylinder 22 so as to always be between the first and second seals 86, 88 regardless of the position of piston 48. This ensures that no oil will enter the crankcase 28 and contaminate the air therein and/or the intake and exhaust ports.
  • Oil return line 36a returns oil to the oil reservoir 30.
  • a piston rod 54 as shown in Figure 5A may be used. Accordingly, a conduit is provided that extends through the wrist pin 56 to a central groove (port) 106 in fluid communication with the annular oil chamber 84 via grooves 102a and 102b to the piston rod 54 and along the piston rod 54 to the crank bearing along piston rod passage 108, as described above with reference to Figures 1 - 5 or 6-8.
  • the oil that lubricates the crank bearing does not flow from it back to the oil reservoir 30. Rather, oil reaching the crank bearing is trapped by seals and does not travel along the crankshaft as described above with reference to Figures 1-5 or 6-8.
  • the reciprocating motion of the piston 48 and the piston rod 54 will continually move oil throughout the various passages and grooves in the wrist pin 56 and piston rod 54. This action avoids stagnation of the oil and carbonizing. If desired, oil can be flooded into and out of the piston through several openings in the piston body.
  • a peltate may be provided in the passage of the piston rod 54, etc. to enhance oil movement. Moving air in the crankcase helps cool the wrist pin, piston rod and crank bearings, as known in the art. Cooling may be enhanced by providing cooling fins to help dissipate heat.
  • the cross-sectional area of the piston is reduced, as shown generally at A in Figure 9, along at least a portion of the length of the piston between the upper and lower seals 86, 88.
  • the piston may have a reduced diameter.
  • the cross-sectional area of the piston is reduced such that it enlarges the volume of the oil chamber 84 and therefore may provide an enhanced lubricating and/or cooling effect.
  • the oil pump may be replaced or supplemented by one or more one-way or check valves provided along the oil passages, e.g. along the piston rod.
  • the inertia of the piston, crank and/or connecting rod is relied upon to move oil along the passages, the valves preventing simple reciprocation and enabling circulation of the oil.
  • a scavenging oil pump is provided to drain any minimal amounts of oil that may leak past the piston's lower seal into the crankcase.
  • the bottom of the crankcase is provided with a port and one-way valve to permit such minimal amounts of oil in the crankcase to be expelled to the reservoir under pressure during the piston's downstroke, and to prevent suction of oil from the reservoir into the crankcase during the piston's upstroke.
  • the lubrication system of the invention unlike conventional engines (especially two-strokes) is a dry- sump system wherein the crankcase is substantially free of oil and therefore allows engine operation without the wasteful and polluting combustion of lubricating oil entering the cylinder from the crankcase. Emission of unburned hydrocarbons is thereby reduced.
  • the lubrication system provides an oil-free crankcase which allows the engine to be operated in any position, attitude or orientation and is advantageous for hand-held tools, aircraft, etc.
  • An engine according to the invention using a dry-sump lubrication system promises to provide engines (particularly two-stroke) having relatively low unburned hydrocarbon emissions, reduced lubricating oil combustion, and greater fuel and oil economy than conventional two-stroke engines currently in use. Additionally, the present invention may be combined with features including: (1) separate scavenging and charging air flows; (2) a throttleable charging air flow; (3) a port opening sequence wherein the exhaust port opens, followed by the scavenging port opening, followed by a charging port opening; and (4) variable exhaust port timing, as disclosed in U.S. Patent No. 6,397,795.
  • the present invention may be incorporated into an engine having separate scavenging 41 and charging 43 tubes to separate the scavenging and charging air streams and result in a reduction of unburned hydrocarbons in two-stroke engines, as disclosed in U.S. Patent No. 6,397,795.
  • a scavenging port 41 A in the cylinder 22 is uncovered to allow air from the crankcase to flow through the scavenging tube 41 and the scavenging port 41 A as it is displaced out of the crankcase 28 by the descending piston 48.
  • unburned hydrocarbon emission is greatly inhibited (trapping efficiency is higher) because: (1) scavenging of exhaust gas is accomplished by a separated flow of air from the crankcase 28 which has no fuel or oil in it; (2) the scavenging flow precedes the charging (air/fuel) flow into the cylinder 22; and (3) mixing between the charge and the exhaust gas in the cylinder 22 is inhibited because this must take place through the intermediary of the scavenging air, and before any substantial mixing has time to occur, most of the exhaust gas will have been displaced out of the cylinder 22.
  • the intake flow is divided into separate charging and scavenging flows, and at partial-load, only the charging flow need be throttled, leaving the scavenging flow without pressure drop, and reducing the total amount of pumping power needed at partial-load, and thus increasing the engine's efficiency and allowing high efficiencies.
  • the scavenging air flow tube 41 is directed toward the exhaust port
  • the port 43A to the charging tube 43 is opened to admit the fuel/air charge.
  • the charging flow is directed toward the spark plug 24 to provide for stratified fuel charging. This results in a reduction of pollution and oil/fuel consumption.
  • Figure 10 also shows a small opening or port, optionally fitted with a one-way valve as shown, toward the bottom of the crankcase 28 for draining any minimal amounts of oil that might leak into the crankcase. Drained oil is returned to the reservoir 30, without the need for a scavenging pump, through the valve under pressure during a downstroke of the piston 48.
  • the one-way nature of the valve prevents suction of oil from the reservoir 30 into the crankcase 28 during the piston's upstroke. Similar structure is shown by way of example in Figure 13 but may be incorporated into any embodiment shown.
  • the present invention is combined with the teachings of U.S. Patent No. 3,973,532 to Litz and/or U.S. Patent No. 6,397,795, to provide a supercharging effect. More specifically, in four-stroke engines, considerably more crankcase charging volume and pressure can be achieved. Air enters the crankcase through a one-way valve and is compressed as disclosed in U.S. Patent No. 3,973,532 to Litz (see Figures 11-15). The compressed air is forced, e.g. during the intake and power strokes, through a one-way valve 172 into a holding chamber/intake manifold or transfer tube 170 to the intake valve to the combustion chamber. This arrangement is disclosed in greater detail in U.S. Patent No. 6,397,795.
  • an additional pressure-operated valve (not shown) is added in the cylinder head that opens automatically to admit ambient air into the cylinder, filling it during the intake stroke.
  • the conventional cam-operated combustion chamber intake valve is configured to stay closed until just before the intake stroke is completed, at which time it opens to top off the ambient air already in the cylinder with pressurized air from the holding chamber.
  • an additional cam-operated intake valve 160 is provided in addition to the conventional intake and exhaust valves 120, 140, respectively.
  • the conventional intake valve 120 opens when the intake stroke begins and closes when the additional intake valve 160 opens (at or very near the bottom of the intake stroke) to add pressurized air to the cylinder 22 from the holding chamber 170, as shown in Figures 15A and 15B.
  • the positions of the valves during the compression, power and exhaust strokes are shown in Figures 15C-15E.
  • variable exhaust valve timing may be employed.
  • the present invention may be incorporated in an engine having variable exhaust valve timing effected through use of a movable exhaust port valve, such as pivoting gate valve 39 ( Figure 10) or eccentric tapered or conical spool valve.
  • the spool valve may be used for achieving a reliable seal and to provide for easy assembly and maintenance.
  • the gate valve 39 increases or decreases the height of the exhaust port 38 to vary the timing of the exhaust port's opening and closing.
  • Such variable exhaust valve timing is disclosed in U.S. Patent No. 6,397,795.
  • manipulation of the exhaust valve may be used to reduce escape via the exhaust port of the incoming air/fuel charge, to adjust the exhaust pulse, to tune for various engine speeds, or to vary compression to achieve dieseling or auto- ignition, if desired, as generally discussed in articles titled, Quick Take: Honda EXP-2, [online] [Retrieved on 9/30/2002] Retrieved from the Internet using ⁇ URL http://www.motorcvcle.com/momchonda/exp2.html and Honda EXP-2, [online] [Retrieved on 9/30/2002] Retrieved from the Internet using ⁇ URL http://www.motorvcle.com/mo/mchonda/exp tech.html, the entire disclosure of both of which are hereby incorporated herein by reference.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Lubrication Of Internal Combustion Engines (AREA)

Abstract

Moteur à combustion interne (20) possédant un système de lubrification améliorée. Des joints supérieur et inférieur (85, 88) sont montés autour du piston (48) afin de définir une chambre de graissage annulaire (84) coopérant avec le piston (48) et le cylindre (22). Pour des moteurs quatre temps, un anneau de compression (100) peut jouer le rôle de joint supérieur (86). Dans des moteurs deux temps, des joints supérieur et inférieur (86, 88) sont présents en plus des anneaux de compression (100). La chambre annulaire (84) est reliée par des conduits à un réservoir d'huile (30). Une pompe fait circuler l'huile à travers la chambre annulaire (84) afin de lubrifier au moins le cylindre (22) et le piston (48). Des conduits contigus à la chambre annulaire (14) peuvent servir à lubrifier l'axe de piston (56), la tige de piston (54), le palier de vilebrequin et/ou le palier principal (60). Ceci permet de séparer le réservoir (30) du carter moteur (28) et, par conséquent, de diminuer les émissions nocives dues à la combustion de l'huile.
PCT/US2002/039214 2001-12-04 2002-12-04 Moteur a carter sec WO2003048541A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002351306A AU2002351306A1 (en) 2001-12-04 2002-12-04 Engine with dry sump lubrication

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US60/337,061 2001-12-04
US10/266,728 US6644263B2 (en) 2001-12-04 2002-11-26 Engine with dry sump lubrication
US10/266,728 2002-11-26

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021090011A1 (fr) * 2019-11-06 2021-05-14 Dice Industries Ltd Moteur à combustion interne

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973532A (en) * 1973-11-09 1976-08-10 Harold Litz Crankcase-scavenged four stroke engine
US4280455A (en) * 1978-01-30 1981-07-28 Fuji Jukogyo Kabushiki Kaisha Internal combustion engine
US5983851A (en) * 1997-05-23 1999-11-16 Honda Giken Kogyo Kabushiki Kaisha Method for lubricating a two-cycle internal combustion engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973532A (en) * 1973-11-09 1976-08-10 Harold Litz Crankcase-scavenged four stroke engine
US4280455A (en) * 1978-01-30 1981-07-28 Fuji Jukogyo Kabushiki Kaisha Internal combustion engine
US5983851A (en) * 1997-05-23 1999-11-16 Honda Giken Kogyo Kabushiki Kaisha Method for lubricating a two-cycle internal combustion engine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021090011A1 (fr) * 2019-11-06 2021-05-14 Dice Industries Ltd Moteur à combustion interne

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