Patent Grant
8596240
Various embodiments relate to internal combustion four-stroke engines and, more particularly, to integrally cast blocks containing cylinders, crankcase portions, and gaseous fuel system.
Conventional four-stroke engines have certain disadvantages because there are numerous parts as compared to two-stroke engines. The additional parts, for example include, valve trains consisting of intake and exhaust valves, followers in the case of push tube trains for transmitting motion from cam lobes to rockers, just rockers in the case of overhead cam and belt or chain drives for overhead cam types. Also included are cam gear or pulley as the case may be, valve springs and retainers, cam shafts, and cam covers in some cases. Also, the method of assembling the main components varies depending on how the cylinder, crankcase, crankcase cover, piston rod and crankshaft assemblies are made.
It is known in the prior art that four-stroke engines have cylinder blocks (with or without a separate cylinder head) and crankcases as the case may be with or without crankcase covers. For example, cylinders manufactured by MTD Southwest has a cylinder head integral with the cylinder and has a separate crankcase which has main bearings to support the crankshaft and a separate volute attached to the crankcase. The volute also has bosses for an ignition module. Another example is a Honda engine which has a cylinder block including a cylinder, where the upper half of the crankcase is integral with the cylinder block and a lower half of the crankcase which, when assembled together, support the main bearings. In this case, there is no separate crankcase cover and the belt drive for the overhead valve system is a wet type, where the upper and lower half of the crankcases together form a reservoir for the lubricating oil and the belt is completely enclosed. The enclosure is integral with the upper half of the crankcase. A similar design is used for a push tube type of valve train. Reference may be made to U.S. Pat. Nos. 6,539,904, 6,672,273, 6,427,672, 6,508,224, 6,705,263 (belt drive), and 6,021,766 (push tube). US patent describes a four-stroke engine with mist lubrication where the crankshaft is fully supported on both sides. It has an oil reservoir on one side of the crankshaft and also a flywheel and a starter on the same side, while the opposite side has clutch and power take off shaft (29). The disadvantage is that the over all length of the engine is longer and heavier. Secondly the full crank engine requires expensive bearings and a full shaft that is heavier and expensive.
Some Honda full crank engines have the crankcases split at an angle to the crankshaft as disclosed in U.S. Pat. Nos. 6,250,273 and 6,644,290. The front half of the crankcase is integral with the cylinder block and has bearing boss to support the front half of the crankshaft and the rear half of the crankcase has another bearing boss to support the outboard side of the crankshaft. The cam gear or the pulley for transmitting the motion to the overhead valves is in the outboard side. One disadvantage is that the U.S. Pat. No. 6,250,273 discloses the need for a cam side cover 14 to hold the cam shaft and gear, as such the prior art requires additional parts, fasteners, and gaskets. In both U.S. Pat. Nos. 6,250,273 and 6,644,290, the crankshaft requires the outboard bearing support 132 to structurally support the crankshaft and cannot be built without support 132. In comparison, the presently disclosed engine has two bearing supports on the same side and does not need additional bearing support on the outboard side.
Another example of engines with push tubes are disclosed in U.S. Pat. Nos. 6,213,079, 7,243,632, and 6,119,648. Some engines use gears to transmit rotation from crankshaft to the overhead cam shaft, which is running at half the crankshaft speed as disclosed in U.S. Pat. Nos. 6,152,098 and 6,612,275. In most cases where the engine has a two piece block, the top or front half and lower or outboard half of the crankcase, the valve train is on the outboard side.
In the case of upper and lower halves of crankcases (or left and right halves as in Kioritz U.S. Pat. No. 6,119,648, the disadvantages are that the upper and lower halves are first assembled together and then the bearing bores are machined. They are taken apart for the final assembly. They are not interchangeable. A sealing gasket is used to seal the two halves. As such, the cost of such a system is higher than the one proposed in the design disclosed herein. Simpler designs as disclosed in U.S. Pat. Nos. 7,559,299 and 2,218,332 include mono-block two-stroke engine designs. However, the two-stroke engines do not have valve train or valves and therefore are simpler to manufacture. Secondly the passages provided are for transfer passages connecting the crankcase chamber directly to the bottom of the cylinder to the combustion chamber have function to communicate between the crankcase chamber and combustion chamber and do not have valve train the passages and cannot be constructed to have the valve train in the transfer passage. U.S. Pat. No. 4,513,702, discloses a valve train having a cam shaft perpendicular to the crankshaft axis necessitating dual cams, one each for intake and the exhaust valve, as such a single cam lobe as disclosed in this invention cannot be fitted into the design disclosed in U.S. Pat. No. 4,513,702. Also, the opening is inclined and overhead cam shaft cannot be driven by a belt.
In the U.S. Pat. No. 6,736,796, the crankcase ventilation system is achieved by providing radial and axial passages in the crankshaft that communicate the crankcase chamber to the intake system. The crankshaft is a load bearing shaft and made of hard steel, as such expensive to drill the passages. Secondly, the passage is always open in the crankcase chamber and likely that the oil can get inside the passage when the engine is stored in different attitudes and the oil eventually may get into the intake system or leak in the air-filter.
In most engines, fuel is mixed with air using a simple carburetor. However, the disadvantages of the carburetor systems are that it needs a manual choke and does not compensate for variation in ambient and operating temperatures. Thus the fuel consumption is higher and hence brake specific emission is higher. There are more advanced electronic fuel systems commonly used in automobiles and some small engines. Prior arts, for example U.S. Pat. Nos. 7,331,315, 7,536,983 and PCT US2007/074982 describe electronic fuel injection system for small two-stroke engines, and they have fuel pumps that depend on engine pulses for pumping the fuel at a certain pressure, thus becomes unreliable as they entirely depend on crankcase pulses. Some engines use electrical or mechanical pumps for delivery fuel at a higher pressure to the injector. Secondly they all use gasoline as fuel. In the prior art U.S. Pat. No. 6,609,509 the fuel used is LPG (liquefied petroleum gas), however, the system is more of a carburetor type than electronically controlled injection system. In the U.S. Pat. No. 7,424,886, the engine described has an LPG tank attached to the engine or the frame and the engine shaft is attached to a generator. The engine described has a carburetor 24, which is likely to leak fuel when the fuel supply line is ON and the engine is not running.
Thus, engine designers are constantly trying to design engines that have less parts, are simpler, and less expensive to manufacture and electronically controlled fuel system.
An integrally cast four-stroke engine mono-block (10) includes integrally cast cylinder block (20), cylinder head (40), and portion of a crankcase (30) including crankcase outboard and inboard walls (89, 90). At least parts of outer and inner bearing bosses (21a, 21b) are integrally cast with the cylinder block (20) with the inner bearing boss (21b) integrally cast in the inboard wall (90). At least one cored out longitudinally extending open valve train chamber (88) is disposed between the outboard wall (89) and the cast cylinder block (20).
An alternative embodiment of the integrally cast four-stroke engine mono-block (10) includes integrally cast cylinder block (20), cylinder head (40), and portion of a crankcase (30) including crankcase outboard and inboard walls (89, 90) and at least parts of an outer bearing boss (21a) and/or an inner bearing boss (21b) integrally cast in the outboard and inboard walls (89, 90) respectively with the cast cylinder block (20). At least one cored out longitudinally extending open valve train chamber (88) is disposed between the outboard wall (89) and the cast cylinder block (20).
The integrally cast four-stroke engine mono-block may further include one or more cored out train passages in the valve train chamber (88) such as push tube passages (88e) or a belt drive passage (1288e). The mono-block may further include an outer ignition boss (1012) integrally cast with the block (10). A portion of an outboard bearing boss (731) such as an upper half (733b) of the outboard bearing boss (731) may be integrally cast with the block (10). The mono-block (10) may include a crankcase inboard wall (90) integral with the block (10) and at least portions of outer and inner bearing bosses (21a, 21b) in the outboard and inboard walls (89, 90) respectively.
Another alternative embodiment of the integrally cast four-stroke engine mono-block (10) includes integrally cast cylinder block (20), cylinder head (40), and portion of a crankcase (30) including crankcase outboard and inboard walls (89, 90) and an outboard wall extension (730). An outboard bearing boss (731) is disposed in the outboard wall extension (730) and first and second bearing bores (723a, 723b in the outboard and inboard walls (89, 90) respectively. At least one cored out longitudinally extending open valve train chamber (88) is disposed between the outboard wall (89) and the cast cylinder block (20).
An integrally cast four-stroke engine L-head mono-block (10) includes integrally cast cylinder block (20), L-head (1440), and portion of a crankcase (30) including crankcase outboard and inboard walls (89, 90). At least parts of an outer bearing boss (21a) and/or an inner bearing boss (21b) are integrally cast in the outboard and inboard walls (89, 90) respectively with the cast cylinder block (20). At least one cored out longitudinally extending open valve train chamber (88) is disposed between the outboard wall (89) and the cast cylinder block (20) and the L-head (1440) covers the valve train chamber (88) and a cylinder bore (12) disposed within the cylinder block (20) and spaced apart from inboard wall (90).
An internal combustion four-stroke engine includes a cylinder block (20) integrally cast with a portion of a crankcase (30) including crankcase outer and inner walls extending downwardly from the cylinder block (20) and integrally cast with a cylinder head (40) extending downwardly from the cylinder block (20). The engine further includes inner and outer bearing bosses (21a, 21b) in the crankcase outer and inner walls respectively, an outboard wall (89) integral with the cast cylinder block (20), at least one cored out longitudinally extending open valve train chamber (88) disposed between the outboard wall (89) and the cast cylinder block (20), a half crankshaft (22) disposed through inner and outer bearings (41, 28) supported within the inner and outer bearing bosses (21a, 21b) respectively, and a valve train (2) extending through the valve train chamber (88) operably connecting and for transmitting motion from the crankshaft (22) to intake and exhaust valves (98, 99).
The engine may further include a counter-weight (32) mounted on the crankshaft (22) inboard of the inner bearing (41) and the valve train (2) may include push tubes (300) disposed in the valve train chamber (688) and operably associated and ridingly engaged with channels (609) in cam lobes (608) mounted on the half crankshaft (22) between the inner and outer bearings (41, 28).
An internal combustion four-stroke engine L-head engine includes an integrally cast four-stroke engine L-head mono-block (10) including a cylinder block (20) integrally cast with an L-head (1440) and at least portions of a crankcase (30) including crankcase outboard and inboard walls (89, 90). At least parts of an outer bearing boss (21a) and/or an inner bearing boss (21b) are integrally cast in the outboard and inboard walls (89, 90) respectively with the cast cylinder block (20) and at least one cored out longitudinally extending open valve train chamber (88) is disposed between the outboard wall (89) and the cast cylinder block (20). The L-head (1440) covers the valve train chamber (88) and a cylinder bore (12) is disposed within the cylinder block (20) and spaced apart from inboard wall (90). A half crankshaft (22) is disposed through inner and outer bearings (41, 28) supported within the inner and outer bearing bosses (21a, 21b) respectively and a valve train (2) extends through the valve train chamber (88) operably connecting and for transmitting motion from the crankshaft (22) to intake and exhaust valves (98, 99). The engine may further include an L-head valve chamber (107) in the valve train chamber (880) and an intake valve assembly (120) for intake and an exhaust valve assembly (120b) for exhaust in the L-head valve chamber (107). A passage (502) may be incorporated to connect a carburetor (500) and the crankcase chamber (48) through a connecting passage (127) in the intake valve assembly (120). A one-way valve (128) may be disposed in the passage (502) to prevent flow back through the carburetor (500) into ambient and first and second intake passages (126a, 126b) connecting the carburetor (500) to the combustion chamber (51) in the cylinder bore (12) through the intake valve assembly (120).
First and second intake passages (126a, 126b) may be used to connect a carburetor (500) to a combustion chamber (51) in the cylinder bore (12) through the intake valve assembly (120) and a carburetor valve (584) of carburetor (500) having first and second valves (584a, 584b) may be incorporated to regulate mass flow into the first and second intake passages (126a, 126b) respectively.
In an alternate fuel mixing system, the conventional carburetor 500 may be replaced by a dual (or a single) intake electronic LPG fuel (9101) injection throttle body 9400, where the first and second intake passages (126a, 126b) are respectively connected to the secondary intake passage (9480) and primary intake passage (9180) in the throttle body (9102) to connect to a combustion chamber (51) in the cylinder bore (12) through the intake valve assembly (120) and a carburetor valve (9584) of EFI throttle body (9400) having first and second valves (9432, 9162) may be incorporated to regulate mass flow into the first and second intake passages (126a, 126b) respectively. The EFI throttle body (9400) may have an electronically controlled LPG fuel injector (9138), either in the throttle body 9102 or in the intake passage (126b). The single intake electronic fuel injection throttle body (9100) may have a single intake passage (9180), when the over head valve engine (1) and the L head engine (1500) have a single intake passage (126). The pressurized LPG fuel (9101) is supplied from an external pressure regulator (2917), that may be integral to the cylinder block (20). The LPG fuel (9101) is contained in a fuel tank (2007). The timing and amount of fuel (9101) injection is controlled by an ECU (9136), based on the received input signals, such as crank angle position from a crank angle position sensor (9412) through a wire harness 9114, the speed is measured through the same sensor or from the ignition pulses received by the ignition module (9404), intake temperature as measured by the sensor (9146), possibly cylinder block (20) temperature, and throttle position from the sensor 9142.
At least some of the engines (including L head engine) may further include a crankcase cover (1312) covering a crankcase chamber (48) within the crankcase (30) and separating the crankcase chamber (48) and from an oil sump (1348) between the crankcase cover (1312) and the sump wall (1344). A tube (1320) extending between the crankcase chamber (48) and the oil sump (1348) protrudes from the crankcase cover (1312) into the oil sump (1348). Alternatively a pocket wall (1314) surrounding a pocket (1316) protrudes into the oil sump (1348). One or more oil passages (1328) in one or more standoff tubes (1324) may incorporated to protrude from the crankcase cover (1312) into the oil sump (1348). The bottom end of the pocket wall (1314) may be closed but have a small orifice, as described in U.S. Pat. No. 2,959,164.
The internal combustion engine may include a crankcase cover (44) covering a crankcase chamber (48) within the crankcase (30) and a fuel tank (2007) operable for holding liquefied petroleum gas or another compressed gaseous fuel for use in the engine and partially disposed in a recess (45) in the crankcase cover (44). The tank (2007) is spaced slightly apart from and conforms to the recess (45). An injecting tube (101) may be disposed in an intake passage (126) disposed between the carburetor (500) and the crankcase chamber (48). A crankcase cover (44) covering a crankcase chamber (48) within the crankcase (30) may be constructed to accommodate a fuel tank (2007) for holding liquefied petroleum gas or another compressed gaseous fuel for use in the engine. The tank is partially disposed in a recess (45) in the crankcase cover (44) and spaced slightly apart from and conforms to the recess (45).
At least some of the half crank engines may further have an outboard shaft 222 loosely connected to the crank pin (736)through an yoke (1450). The outboard shaft (222) has at least one oil slinger (1234b) to splash oil (1340) and generate mist of oil. The out board oil reservoir cover (9310) attached to the crankcase cover (44) and it also encloses the oil slinger (1234b). The outboard shaft (222) has an axial passage (808b) and a radial passage (809a) connecting the oil reservoir (1250) and the crankcase chamber (44). The radial passage (809b) has opening (809) that is intermittently opened and closed by a cut out (9042) in the bush bearing (9041). The crankcase chamber (44) has an oil drain port (999b) through which the condensed oil drains into an intermediate chamber (9348)and back into the oil reservoir (1250) through an oil return passage (9350). The oil drain port (999b) has a non-return valve (999) to intermittently open and close the oil drain port (999b). The crankshaft (22) and the counter weight (32) have an axial passage (808a) and a radial passage (808c) to connect the crankcase chamber (44) to an oil recovery chamber (107b), through a oil breather tube (911) and has a check valve (914) at the end of the tube (911). Similar connecting passage may be provided through the cam shaft (298), which as a passage (83). The oil recover chamber is typically part of the air cleaner box (not shown). The oil condensed in the oil recovery chamber (107B) is drawn back into the crankcase chamber (48) through an oil return port (824) in the cylinder bore (12) and the port (824) is intermittently opened and closed by the piston (756). The oil return tube (826) connects the oil recovery chamber (107b) to the oil return port (824). The dry crankcase charge collected in the oil recover chamber (107b) is inducted into the engine through the breather tube (827). The starter assembly (not shown) and the clutch assembly (not shown) are on the outboard side of the engine coupled to the outboard shaft (22).
The outboard shaft (222) may further have an extension shaft (222b) passing through the oil reservoir cover (9310). The extension shaft (222b) may further have a starter slot (222d) for coupling an external starter.
Further there can be an oil pump (1505) in the oil reservoir (1250). The oil pump (1505) is driven by the outboard shaft (222b) has an oil inlet tube (1507) and an outlet tube (1509). The oil pump (1505) injects oil into the crankcase chamber (48).
Further, half crank engine 1800 may have an outboard manual starter (1820) consisting of a starter shaft (222c) having a yoke with a ‘U’ slot (1541) which loosely engages the crankpin 736. Therefore, the outboard shaft does not bear any load coming from the piston due to combustion of fuel-air mixture. The centerline (2927b) of the countershaft (222c) need not be in line with the center line (2827) of the crankshaft (22). The yoke (1540) is rigidly fixed to one of the end of the starter shaft (222c) inside of the crankcase chamber (48), while the other end has the starter cup (1852). The starter shaft (222c) is straddle mounted by a bearing (728b) on the inboard side and a sealed bearing (928d) closer to the starter cup (1852). An oil seal (928c) is installed on out board side of the bearing (728b) and has space (809) between the oil seal (928b) and the outboard bearing (928d). The opposite end of the ‘U’ slot (1541) in the yoke (1450) has a radial passage or a separate tube (not shown) (808d) that communicates with the axial passage (808e). The radial passage (808f) is between the oil seal (928c) and the outboard sealed bearing (928d). The space (809) has communication with the oil separator chamber (707). The condensed oil in the separation chamber (707) is then fed into the combustion chamber during the intake process. The condensed oil in the separation chamber (707) is returned to the crankcase chamber (48) when the piston (756) opens the oil return port (824). The outboard starter (1870) functions in a commonly known manner. The bearings (728b) and the outboard bearing (728d) are supported on a boss (731b) in the crankcase cover (44). The boss (731b) is projected inboard into the crankcase chamber (48) providing a cavity (49) around the boss. The cavity (49) is necessary to keep the oil from entering the radial passage (808d) in the yoke (1540) when the engine is stored with outboard starter (1870) downward position. The radial passage (808d) may have any one of the type of on-off valves (900) (902) (904) that is normal shut off when the engine (1800) is not running. The valve (900 for example) opens when the engine starts to run. In other words, when the outboard starter shaft (222c) starts to rotate above 100 RPM. The Valve (900) is shut closed when the engine is shut off. Therefore the oil in the crankcase chamber (48) prevents the oil from leaking from the crankcase chamber (48) when the engine is stored in any attitude. Different types of valve, for example (900), (902), or (904) and many other equivalent types operate by the principle of centrifugal force, where the centrifugal force, as the engine runs, forces the weight away from the center, thus opening the radial passage (808d) at the port (913b).
Accordingly, various embodiments provide a new mono-block and engine incorporating the mono-block and an improved method of cylinder manufacturing and assembling the four-stroke engines, particularly, four-stroke engines (applicable to two-stroke engine cylinders as well). A single piece cylinder crankcase block for half and full crank allow for the manufacture and assembly of a lower cost engine. A simpler crankcase for dry sump lubrication can also be used as the dry sump engine/mist lubrication allows engines for any attitude operation when used in hand-held applications.
The low cost simpler four-stroke engine is especially suited for hand-held, lawn and garden equipments such as trimmers, blowers, chainsaws, cultivators, lawn mowers, compressor engines, and generator engines. The method manufacturing the cylinder block is simplified.
Conventional four-stroke engines have cam shaft and reduction gear for running the cam lobes at half the crankshaft speed to operate the intake and exhaust valves only once every two rotations of the crankshaft speed. However, in the mono-shaft engine, the cam lobe is either integral with the counter-weight or a separate piece mounted on the crankshaft in a chamber between the bearing bosses.
The mono-block engine reduces the number of parts, particularly, the half-crank engine and simplifies the method of assembling the full crank engine. Further, the engine design disclosed here is applicable to a full crank engine, where in both the outer and inner main bearing bosses are cast in as a single piece, but has a new assembly procedure.
Some four-stroke engines have a breather system for discharging excessive blow-by gases through the cam shaft, particularly, in the case of push tube type valve train system. The cam shaft, in this case, is substantially parallel to the crankshaft and is mounted between the cylinder head and the crankshaft. The breather passage is in the cam shaft and it can be a stationary shaft, where the cam gear and lobe are rotating on the shaft. Further, there can be a breather passage in the crankshaft connecting the chamber to the ambient (instead of breather passage in the crankshaft).
The compact mono-block design as disclosed for an L-head engine provides a significant advantage when an LPG fuel tank is attached to the crankcase cover.
Further, in developing countries and remote areas in the US, the LPG is commonly used as a cooking gaseous fuel. In most cases the LPG fuel is stored in a tank at significantly higher pressure of the order of 50 psi or so. In the US most residents have compressed natural gas as fuel for cooking and are supplied to residents through a pipe line. The following explains an LPG or a gaseous fuel injected portable generator using the residential gaseous fuel commonly used for cooking and heating. The advantage with the gaseous fuel injected engine is that the fuel supply line need not be turned off when the engine is not running, as the leak rate is almost zero in a gaseous fuel injected system compared to a gaseous fuel carburetor. The engine 2000 has generator magneto wheel (2029) mounted on the in board crankshaft 22. The magneto has magnets (2406 on the inside periphery of the magneto wheel (2029). The generator coils (2040) are mounted on a plate (2042), which is stationary and mounted on to the crankcase (30). The fuel supply system (2002) has an LPG fuel tank (2207) supplying gaseous fuel to a gas stove (2060) through a pressure regulator (2919) and a fuel line (2062). The fuel supply line (9126) to the engine throttle body is ‘T’d off of the main fuel line (2062). Typically, the engine can be cranked for starting using an electric starter, as described earlier or by hand cranking. The advantages with LPG injected fuel system for a portable generator (2000) are that the fuel system has very minimum maintenance and fuel does not have to be shut off. Secondly, fuel that is already used for cooking can be used for the power generator engine as well. The electric starter can be powered by a battery, which is trickle charged by the generator. The Power generator in a residence is typically used as a electricity backup system for emergency.
b is a cross-sectional side view illustration of a mono-block having integrally cast cylinder block, crankcase, cylinder head, and outer and inner bearing bosses in the engine illustrated in
c is a cross-sectional front view illustration of the engine illustrated in
d is a cross-sectional top view illustration of the engine illustrated in
b is a cross-sectional side view illustration of another exemplary embodiment of a mono-block four-stroke engine with a cam shaft driven oil pump.
b is a cross-sectional view illustration of the engine illustrated in
bb is a cross-sectional side view illustration of a mono-block having integrally cast cylinder block, crankcase, cylinder head, and bearing boss in the engine illustrated in
c is a cross-sectional side view illustration of another embodiment of the mono-block four-stroke engine with a half-crank and one half of the outboard bearing boss being integral with the cylinder block.
b is a cross-sectional view of mono-block four-stroke engine with cam cover and integral boss for mounting the ignition module.
b is a cross-sectional side view illustration of another embodiment of the mono-block four-stroke engine with a belt driven overhead cam and an oil pump driven by the crankshaft.
b is a cross-sectional side view illustration of the engine in
c is a cross-sectional side view illustration of the engine in
b is a cross-sectional side view illustration of a mono-block having integrally cast cylinder block, crankcase, cylinder head, outer and inner bearing bosses in the engine illustrated in
c is a cross-sectional front view illustration of another embodiment of a mono-block having integrally cast cylinder block, crankcase, cylinder head, outer and inner bearing bosses, valve assembly on the side of the cylinder block in the engine illustrated in
d is a cross-sectional top view illustration of another embodiment of an engine with a divided intake system with one way valve in one intake passage and oil injection into said passage.
e is an enlarged cross-sectional view illustration of engine illustrated in
f is a cross-sectional side view illustration of an exemplary embodiment of a four-stroke engine with a L-head and a valve train with LPG fuel tank at the bottom.
The outer frame 25 may be designed either for a reverse or forward air flow. Reverse air flow is where the frame has openings around the outer circumference for flow of air from behind the engine and forward air flow has openings in the front housing for flow of air. The combination of forward and reverse air flow has openings in the frame 25 as well as in the front housing for flow of air. A longitudinally extending open valve train chamber 88 disposed in the mono-block 10 between the outboard wall 89 and the cylinder block 20, a lower opening 88a at a lower end 87 of the valve train chamber 88 that may be closed with a cover 89a, if necessary, or may be open to a crankcase chamber 48. The frame 25 extends down from the outboard wall 89 and at least a portion of the frame 25 is integrally cast with the outboard wall 89. A top end 86 of the valve train chamber 88 located near the cylinder head 40 is open to allow the valve train 2 to transmit motion from crankshaft 22 to an intake valve 98 and to an exhaust valve (not illustrated) which is behind the intake valve 98.
The intake valve 98 and the exhaust valve are in a valve chamber 106 and a spark plug 40b mounted in the cylinder head 40 extends into a combustion chamber 51 defining an upper portion of the combustion chamber 51. The valve train 2 includes cam gear 182, cam lobe 108, followers 288, and push tubes 300 (also referred to as push rods). The valve train chamber 88 houses crank gear 122 and cam gear 182 with the followers 288. The valve train chamber 88 is formed, such as by casting, so that there is at least one slot 34 between the outer bearing boss 21a and the inner bearing boss 21b at the lower end of the valve train chamber 88. The slot 34 illustrated in
The valve train chamber 88 is cored out using a slide in casting tool. The push tubes 300 may be disposed in one or more train passages such as push tube passages 88e in the valve train chamber 88. The train passage may also be a belt drive passage 1288e illustrated in
The top end 86 of the valve train chamber 88 may be open to the overhead valve chamber 106 through the cast in push tube passage (or passages) 88e or may be just open for a dry type belt drive as illustrated in
An embodiment of the engine 1 illustrated in
A cam shaft 82 driven oil injection pump 1505 illustrated in
Illustrated in
Lubrication of the push tube valve train 2 is achieved by providing an oil passage 808 through the center of the crankshaft 22 that runs axially from the crankcase chamber 48 and then radially to the valve train chamber 88. Unlike breather passages disclosed in U.S. Pat. Nos. 6,039,020 and 6,047,678, the purpose is to supply a small amount of oil from the crankcase chamber into the valve train chamber 88, which in turn lubricates the valve train 2. The lower opening 88a is closed and there may be an oil seal in the inner bearing boss 21b or the inner bearing 41 could be a sealed bearing that prevents direct flow of oil from crankcase chamber into the valve train chamber 88.
The small amount of oil that gets on the cam gears 182 and the crank gear 122 is splashed to help lubricate the intake valves 98 and rockers 102a. Oil condensed in the valve train chamber 88 is returned to the crankcase chamber 48 through a check valve 999 on the cover 89a, which opens when the crankcase chamber pressure drops as the piston assembly 756 moves upward. Other types of valves may be used. The opening 88a may be used for many purposes such as described above to have a check valve for return of oil from the valve train chamber 88 to crankcase chamber 48, or can be used to have a oil pump as illustrated in
A full crank engine 700, illustrated in
Assembly of the inboard and outboard crankshaft halves 722a, 722b will be different than the conventional methods. A method of assembling the cam shaft 82, cam gear 182, and the followers 288, as illustrated in
A method of assembling the full crank engine 700 with integral bearing bosses includes assembling first and second counter-weights 732a, 732b, installing crank pin 736 through the first and second counter-weights 732a, 732b, connecting rod 734, as illustrated in
Referring to
Referring to
Referring to
Referring to
Step 5 of the method includes inserting the outboard bearing 731 (or bearings for outboard starter) and oil seals 728b. The outboard bearing may either slide fit on the outboard crankshaft halves 722b and may be secured in place with the circlip.
It should be noted that the oil seal or oil seals may be used in conjunction with the bearings at any bearing bosses 21a, 21b and 731 as necessary depending on lubrication systems and breather systems.
Referring to
b illustrates the assembled engine with a separate oil chamber 948b attached to the bottom of the crankcase cover 944a with a slot 964 for the slinger 934b on the connecting rod 934 to splash the oil. It may be noticed that when the engine is turned upside down, the oil does not poor down into the crankcase chamber 948a because of a separation wall 966. However, the bleed passage 952 allows a small amount of oil to drip onto the first and second counter-weights 932a, 932b so the piston assembly 756 gets lubricated and also some oil goes into the valve train chamber 88 for lubricating the valve train. It is possible to time the opening of the bleed passage 952 with the counter-weight 932a so that the bleed passage 952 is open when the piston assembly 756 moves upward causing negative pressure in crankcase chamber 948a and close it when the piston is in downward motion causing positive pressure in the crankcase chamber 948a. The oil condensed in the valve train chamber 88 and valve chamber 106 is returned to the crankcase chamber 948a or possibly directly back into the separate oil chamber 948b through a check valve 999 illustrated in
In another embodiment of the engine, illustrated in
b illustrate the second bearing bore 723b (an inner bearing bore) as being bored all the way to the inside wall 723d of an outer bearing bore 723e. The leftover material 1011 is then machined out to form valve train chamber 1088. In this case, the lower end 1088a of the valve train chamber 1088 is closed and there is no need for any kind of plug. However, the front face 1189 of the valve train chamber 1088 has to be cored out from the front for inserting the cam shaft 82, cam gear 182 and followers 288 with the follower pin 298. This calls for a separate cam cover 1190 as illustrated in
b illustrate another embodiment of the engine 1200 having a wet belt drive, similar to what is described in the Honda prior art. An overhead cam pulley 1282 running at half the engine speed is driven by a timing belt 1284 and a crank pulley 1286 on the crankshaft 1222. The crank pulley 1286 may be either in a separate chamber 1288 adjacent to the oil chamber 1248b with an oil seal between the two chambers or the valve train and oil chambers 1288 and 1248b may be commonly cored out from the bottom. The slingers 1234b are attached to the crankshaft 1222. There may be more than one pair of slingers. A belt drive passage 1288e is cored out from bottom as well as top of the cylinder block 1210. A follower 102b and a rocker 102a shown in
b illustrate an alternative embodiment of the half-crank engine illustrated in
The L-head valve chamber 107 has an intake valve assembly 120 for intake and an exhaust valve assembly 120b for exhaust that includes an intake valve seat 4002 and an intake valve guide 4024 for intake and an exhaust valve guide 4026 for exhaust. The valve chamber 107 further includes a valve spring 1408, and valve retainer 1409 and is tightly attached to the mono-block 10 in the valve chamber 107 between the chamber 88 and the combustion chamber 51, to form a leak proof combustion chamber 51. The valve assembly may be a modular piece where valve seat 4002, valve guide 4024, valve spring 1408, and valve retainer 1409 are all assembled separately prior to attaching to the mono-block 10. Valve lash is adjusted with a nut 299 through a window 10b (shown in
In another embodiment of the L-head engine 1400 having an integral L-head mono-block 10 illustrated in
Essentially, the divided inlet port 126 may have either only air going into crankcase chamber 48 through passage 126a when oil is injected into the air stream to lubricate the parts, or may have air-fuel mixture when oil is pre-mixed with the fuel, or may have lean air-fuel mixture free of oil when oil is injected into the lean mixture in passage 126a, while rich mixture flows through the passage 126b or the mixture may be of uniform air-fuel ratio going through both the passages 126a, 126b. Also, when only air passes through passage 126a, fuel supplied through passage 126b may be a propane fuel or any gaseous fuel, such as compressed natural gas, bio gas, etc. The advantage of injecting oil into air inducted into crankcase chamber is that the fuel either liquid form as in the case of gasoline or gaseous as in the case of propane can flow directly into the combustion chamber during the intake process, while oil injected into air lubricates the valve train (cam gear, crank gear, followers, valves, cam lobe, etc) and bearings in the crankcase chamber 48 when the engine is a dry sump type without oil in the crankcase chamber 48.
Another advantage is that the engine can be operated in many attitudes as there is no oil in the crankcase chamber that would flow into the cylinder when engine is operated upside down. The dual intake system where port inlet 126 is divided into two separate passages 126a, 126b may also be applied to overhead valve chamber 107 shown in
During the compression stroke when the piston assembly 756 travels upward, the intake valve 98 is closed and the crankcase chamber 48 experiences negative pressure and the charge (oil mixed charge) is inducted into the crankcase chamber 48 from the carburetor 500 through the passage 126a, the port 126, the chamber 88. The one-way valve 128 opens due to differential pressure cross the one-way valve (typically a reed valve is used). When the piston moves downward during power stroke and expansion stroke, the crankcase pressure is built-up. During the intake stroke, the intake valve 98 opens and the charge from the crankcase chamber 48 enters the combustion chamber 51. At the same time, the rich charge enters the combustion chamber 51 directly from the carburetor 500 through the passage 126b. The concept of dual passage (lean charge going into crankcase chamber 48 and rich charge going directly into combustion chamber is applicable to all mono-block engines.
The oil pump may be driven by the crankshaft 22 as shown in
f illustrates the location of an LPG fuel tank 2007 with a radius of curvature R1 near a crankcase cover 44 having a recess in a fractional section 44b of the crankcase cover 44. The recess has a radius of curvature R1 plus a few millimeter (example 2 to 20 mm) to closely match and conform to an outer wall of the LPG fuel tank 2007 at the fractional section 44b of the crankcase cover 44. The radius of curvature on the crankcase cover 44 at section 44b is such that it provides enough clearance for the connecting rod 734 and crank pin 736 to freely rotate without interference. Secondly, a center line 2007a of the fuel tank 2007 is below an axis 2927 of the crankshaft 22 and the center line 2007a is off-set from the axis of the cylinder bore 12 when the fuel tank 2007 is located at the bottom of the engine as shown in
Engine 1400 shown in
U.S. Pat. No. 6,199,532 discloses an engine in which an intake passage is not divided into separate passages and the fuel is pre-mixed with oil and the valve chamber is substantially spaced above the combustion chamber.
The Ignition module 9404 is mounted on boss 1012, and the magnets (not shown) are on the flywheel 9429, which energize coils in the ignition module. There may be additional power coil in the module to supply power to the ECM 9136. The flywheel 9429 is mounted on the crankshaft 22. The crankshaft 22 is used to drive many applications, such as trimmers, blowers, chainsaws, mopeds, lawn mowers, etc.
The engine 1500 may have a wet lubrication system as in the case of the engine shown in
Throttle body 9102 has an integral pressure regulator 9103 consisting of an LPG fuel inlet 9110, pressure chamber 9105, diaphragm 9107, needle valve 9111, arm 9108, pressure spring 9109, vent hole 9129 in the pressure regulator cover 9127.
The pressure P1 is normally at about 50 to 100 inches of water in the LPG tank when the LPG fuel 9101 enters the pressure chamber 9105 where the flow is regulated by the needle valve 9111. The needle valve 9111 is connected to the diaphragm 9107 through a pin 9118 and an arm 9108. As the pressure increases in the chamber 9105 the needle valve closes the flow of LPG fuel because the pressure pushes the diaphragm 9107 outward against a pressure spring 9109. The pressure P2 in the pressure chamber 9105 is controlled by the spring 9109, which may be pre-set to any level equal to or below the inlet pressure P1, The fuel pressure chamber 9105 is connected to a fuel metering chamber 9104 through a passage 9176 between the pressure chamber 9105 and the fuel metering chamber 9116. The metering chamber 9116 is connected to the LPG fuel injector 9138 through a fuel passage 9126, which can also be an external hose outside the throttle body 9102. As the fuel flows into the fuel metering chamber 9116, the pressure P2 in the pressure chamber 9105 drops, thus opening the needle valve 9111 for the fuel to flow into the pressure chamber 9105, thus maintaining almost a constant pressure P2.
The fuel metering chamber 9116 also a diaphragm 9114, needle valve 9122, arm 9124, pin 9118, metering chamber cover 9130 and a vent hole 9128. Operation of the metering chamber 9116 is similar to the pressure chamber 9105, where the pressure P2 now at about 10 inches of water is maintained constant while the fuel is fed to the fuel injector 9138. LPG Fuel in the metering chamber 9116 is connected to the injector 9138 through a fuel passage 9126, as the fuel is depleted in the metering chamber 9116 due to LPG fuel injection into the passage 9180, the pressure P2 drops in the metering chamber. The needle 9122 opens and maintains a nearly constant pressure P2. The needle valve 9122 is activated by the diaphragm through the pin 118 and the arm 124. The needle valve tries to stay closed because of the spring 9120 in the metering chamber 9116. Typically this spring 9120 is a very small spring compared to the spring 9109. Pressure P2 in metering chamber 9116 is slightly lower than P2 due to pressure loss across the needle valve 9122.
The amount of LPG fuel 9101 injected depends on throttle position, intake temperature TI, engine block or exhaust gas temperature TB, engine speed RPM, and sometimes, intake manifold pressure MAP. In addition, an fuel inlet pressure or fuel pressure in the LPG supply line may be input to the ECM so adjust the fuel on time. Fuel supply pressure may be important when the fuel tank is almost empty and that a longer on time may be required to completely empty the fuel tank.
Typically, the EFI system requires a TDC or a crank angle sensor to determine when the injection should occur or spark should occur in a cycle. In a two-stroke engine, the spark occurs every rotation of the crankshaft and also fuel injection occurs every rotation of the crankshaft. However, in a four cycle engine, in most cases, the spark occurs only once every two rotations of the crankshaft. However, in a small engine without any electronic controls or crank angle sensor, the spark occurs every rotation; once in the compression stroke (slightly before TDC) and another time during exhaust stroke. Normally, the occurrence of second spark during exhaust stroke does no harm to performance of the engine, except it may reduce the life of the spark plug, as each spark may erode the electrode. However, the crank angle position is more critical for the fuel injection and typically it is preferable to inject fuel only during the intake stroke, which is most commonly done in an automobile type of engines, because they have a crank angle position sensor, most commonly a sensor to locate the position of the camshaft that rotates at half the engine speed. As such it adds cost to the EFI system, because this type requires a crank angle sensor and a special camshaft having a positioning feature.
However, it is possible to inject small quantities of fuel twice per cycle in a four-cycle engine. This means the fuel is injected once every rotation of the engine; once during intake and once during the expansion stroke. The total amount of fuel injected is a sum of the fuel injected every rotation. As such it is possible not use the crank angle position sensor in a four cycle engine. It is advantageous to inject at an appropriate time during intake process. For example, the fuel injection may occur during the intake stroke within a certain crank angle position. This may be determined by the spark timing and occurrence of fuel injection may be tied to spark timing. Injection during certain crank angles in the intake cycle may help stratification of charge. Because initial intake process may have lean air-fuel mixture, while the later part of intake may have slightly richer charge. Appropriate intake port design helps stratification near the spark plug, that gives lower NOx emission.
However, it is also possible to determine the firing TDC based on the spark timing or the spark pulse the ECM commands to the ignition coil. For example, when the engine is first cranked, the time interval between the sparks indicates the speed. In a small engine, the spark may occur twice per cycle or once every rotation, as explained earlier. When the engine does not fire, the spark interval may be more or less same, or may increase if the engine does not continue to rotate, as in the case of a hand cranked engine. However, when the engine fires, the RPM immediately following the spark increases, thus the time interval between the spark decreases. Therefore it is possible to determine the actual firing spark that occurs during the compression stroke, which can be used to inject the fuel only during the intake stroke. Thus the fuel need not be injected twice, possible a logic may be incorporated to inject fuel only once a cycle in a four cycle engine, without having a crank angle position sensor. Secondly, this logic may be used to spark once only once per cycle, and therefore extend the life of the spark plug.
Further, another engine 1600 shown in
In another engine 1700 shown in
Further, the outlet from the LPG fuel tank may be from the very center of the LPG fuel tank, such that the liquefied fuel never gets out the outlet and the tip is always above the level of the fuel at all attitudes.
Further, it may be possible to have lubricant already mixed into the liquefied fuel such that in the case of crankcase charged design, such as shown in
Further, since the LPG fuel is at a higher pressure and the volume of fuel in gaseous form is substantially higher, the fuel pressure may be utilized to pressure an oil reservoir, where the oil is injected into the crankcase.
Further, a special lubricant already mixed into the liquefied petroleum gas (LPG) helps lubricate the gaseous fuel injector.
Further, an oil reservoir may already be built into the LPG fuel tank, which like in a two-stroke engine is used to lubricate the four-stroke engine as shown in
Further the valve 900, shown in
In another version of the valve shown in
The gaseous fuel injected engine operates in the same manner described earlier. However, the fuel supply system 2002 consists of an LPG fuel tank 2207 (or compressed natural gas tank), which also supplies fuel to the cooking stove 2060 in a residence. The fuel supply line may also be from a utility company that supplies through a network of pipelines supplying fuel to individual residence. The LPG fuel line 9126 has a pressure regulator 2919 that reduces fuel pressure from about 45 to 50 psi to 10 to 15 psi or less. The fuel supply line 9126 has a T junction to supply fuel to the stove 2062.
The engine may started remotely by means of an electric starter couples to the shaft 222c. The engine cooling fans 2030 are integral to the magneto wheel 2029, similar to many small air-cooled engines.
Various embodiments have been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. While certain embodiments have been described herein, modifications shall be apparent to those skilled in the art from the teachings herein and, it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the contemplated embodiments.
The present application claims the benefit of priority of the following applications: U.S. provisional application No. 61/252,685, titled “INTEGRALLY CAST BLOCK AND GASEOUS FUEL INJECTED GENERATOR ENGINE” and filed Oct. 18, 2009; U.S. provisional application No. 61/277,476, titled “INTEGRALLY CAST BLOCK AND LUBRICATING SYSTEM FOR FOUR CYCLE ENGINES” and filed Sep. 26, 2009; and International Application Number PCT/US09/53088, titled “INTEGRALLY CAST BLOCK AND UPPER CRANKCASE” and filed Aug. 14, 2009, each of which is hereby incorporated herein by reference for all purposes.
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| Number | Date | Country | |
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| 20110073064 A1 | Mar 2011 | US |
| Number | Date | Country | |
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| 61252685 | Oct 2009 | US | |
| 61277476 | Sep 2009 | US |
