The present invention relates to a lubrication system for an internal combustion engine. More specifically, the present invention relates to an oil tank arrangement for an internal combustion engine.
Internal combustion engines operating on the four-stroke principle have a lubrication system consisting of various passages inside the crankcase, cylinder block, and cylinder head assembly to lubricate the various components of the engine. On engines having a dry sump, the oil used for lubricating these components is stored in an oil tank. The oil flows from the oil tank to the passages and is returned to the oil tank from the passages after circulating though the engine.
The oil tank is generally in the form of a container that is separate from the engine. To permit oil to flow to and from the oil tank therefore requires various tubes or pipes to be connected between the oil tank and the engine. Installing these connections requires time during the assembly of the engine. Also, as would be understood, the more connections exist, the greater the likelihood of oil leaks. The oil tank, being a separate container, also needs to be installed in the vehicle where the engine is located, which can sometimes be difficult due to the lack of space in the vehicle, particularly in recreational vehicles such as snowmobiles or personal watercraft. Further increasing the difficulty in installing the oil tank in a vehicle is the importance, in relatively lightweight vehicles, to maintain a proper weight balance in the vehicle, which is the case in recreational vehicles. If a mass, such as the oil tank, is disposed in the wrong position, it could negatively affect the performance of the vehicle.
Therefore, there is a need for an internal combustion engine having an oil tank that does not require the above-mentioned connections and can be easily installed in a vehicle.
During the operation of the engine, some of the gases present in the combustion chambers pass through a gap between the pistons and the walls of the cylinders and enter the crankcase. These gases are known as blow-by gases. In the crankcase, the blow-by gases mix with oil droplets. The mixture of blow-by gases and oil droplets present in the crankcase is then returned to the oil tank.
Upon returning to the oil tank, some of the blow-by gases will separate from the oil and rise to the top of the oil tank. However, some of the blow-by gases may remain mixed with the oil. If the blow-by gases are recirculated with the oil in the passages of the lubrication system, they can become trapped in portions of the passages creating a “bubble” of blow-by gases. The portion of the engine where the bubble is located can become very hot since no oil flows in that portion of the passages, which could damage the engine.
Therefore there is a need to separate the blow-by gases from the oil prior to recirculating the oil in the passages of the lubrication system.
The blow-by gases that rise to the top of the oil tank need to be evacuated, otherwise pressure could build up inside the oil tank which could lead to oil leaking from the oil tank or even failure of the oil tank.
To address this problem, most oil tanks are provided with a blow-by gas outlet near or at the top portion thereof which communicates with the exterior of the engine (i.e. the environment or an air intake system of the engine). This outlet allows the blow-by gases to be vented to the exterior of the engine.
If for some reason, the vehicle in which the oil tank is disposed should become overturned, the oil needs to be prevented from leaking into the environment or the air intake system of the engine (as the case may be) via the blow-by gas outlet. This is usually achieved by providing a valve that closes upon detecting that the vehicle has overturned, thus preventing the oil from flowing to the environment or the air intake system of the engine. However, the valve could potentially fail or the sensor associated with the valve could not detect that the vehicle has overturned, which would lead to oil leaking into the environment or the air intake system of the engine. The sensor could also fail and cause the valve to close even though the vehicle did not overturn, which could lead to pressure build-ups inside the oil tank. Also, a valve, and its associated sensor, add cost to the manufacturing of the engine and oil tank and require additional assembly.
Therefore, there is a need to prevent oil from leaking into the environment or the air intake system of the engine when the vehicle in which the oil tank is located becomes overturned without requiring a valve.
Also, when a vehicle such as a snowmobile or all-terrain vehicle goes up or down a hill, or a vehicle such as a personal watercraft or a motorcycle takes a sharp turn, the vehicle becomes angled relative to horizontal, and if that angle is large enough, it may cause the oil in the oil tank to block the blow-by gas outlet. The blow-by gas outlet, being located at or near the top of the oil tank, also becomes blocked when the vehicle overturns. However, the blow-by gases still need to be vented under those conditions.
Therefore, there is a need for an oil tank that can vent blow-by gases even though the blow-by gas outlet becomes blocked by the oil in the oil tank due to the oil tank being angled relative to horizontal or being overturned.
It is an object of the present invention to ameliorate at least some of the inconveniences present in the prior art.
It is also an object of the present invention to provide an internal combustion engine having an integrated oil tank. A part of the oil tank is formed by at least one of the crankcase and the cylinder block. The other part of the oil tank is formed by a enclosure connected to the at least one of the crankcase and the cylinder block.
Integrating the oil tank with the engine eliminates the need for tubes or pipes to be installed between the oil tank and the engine. Also since the oil tank is integrated with the engine, when the engine is installed in the vehicle, the oil tank is simultaneously installed.
It is another object of the present invention to provide an engine having an oil tank with an angled portion. Oil entering the oil tank from the engine flows over the angled portion which causes blow-by gases present in the oil to become separated from the oil.
It is yet another object of the present invention to provide an engine having an oil tank with a blow-by gas outlet where the blow-by gas outlet communicates with a blow-by gas passage which first extends in a direction generally away from the cylinder head assembly, and then extends generally back towards the cylinder head assembly. Due to the shape of the blow-by gas passage, the likelihood of oil leaking into the environment or the air intake system of the engine when the engine and oil tank become overturned is reduced.
It another object of the present invention to provide an engine having an oil tank with a blow-by gas outlet and an oil inlet, where the oil inlet is arranged such that, should the blow-by gas outlet become blocked by the oil in the oil tank due to the oil tank being angled relative to horizontal or being overturned, oil can be vented to the atmosphere via the inlet.
In one aspect, the invention provides an internal combustion engine having a crankcase, a crankshaft disposed in the crankcase, and a cylinder block disposed on the crankcase. The crankcase has a crankcase outer wall. The cylinder block has at least one cylinder. The cylinder block has a cylinder block outer wall. At least one piston is disposed in the at least one cylinder. The at least one piston is operatively connected to the crankshaft. A cylinder head assembly is connected to the cylinder block. An oil tank enclosure is connected to at least one of the crankcase outer wall and the cylinder block outer wall. The oil tank enclosure and the at least one of the crankcase outer wall and the cylinder block outer wall together form an oil tank.
In a further aspect, an oil tank filler neck is connected to the oil tank enclosure. An oil tank cap selectively closes the oil tank filler neck.
In an additional aspect, an oil tank wall extends outwardly from the at least one of the crankcase outer wall and the cylinder block outer wall. The oil tank enclosure is connected to the oil tank wall. The oil tank enclosure, the at least one of the crankcase outer wall and the cylinder block outer wall, and the oil tank wall together form the oil tank.
In a further aspect, the at least one of the crankcase outer wall and the cylinder block outer wall is the crankcase outer wall.
In an additional aspect, an oil outlet is disposed in the crankcase. The oil outlet fluidly communicates with the oil tank for supplying oil from the oil tank to the engine. An oil inlet is disposed in the crankcase. The oil inlet fluidly communicates with the oil tank for supplying oil from the engine to the oil tank.
In a further aspect, a blow-by gas outlet is disposed in the crankcase. The blow-by gas outlet fluidly communicates the oil tank with an exterior of the engine.
In an additional aspect, the oil inlet is disposed in the crankcase outer wall.
In another aspect, the invention provides an internal combustion engine having a crankcase, a crankshaft disposed in the crankcase, and a cylinder block disposed on the crankcase. The crankshaft defines a crankshaft axis. The cylinder block has at least one cylinder. The at least one cylinder defines a cylinder axis. At least one piston is disposed in the at least one cylinder. The at least one piston is operatively connected to the crankshaft. A cylinder head assembly is connected to the cylinder block. A plurality of oil passages is disposed in at least one of the crankcase, the cylinder block, and the cylinder head assembly. An oil tank is fluidly connected to at least one of the oil passages. The oil tank has a first side and a second side opposite the first side. An oil outlet is disposed in the oil tank. The oil outlet fluidly communicates the oil tank with at least one of the oil passages for supplying oil from the oil tank to the oil passages. An oil inlet is disposed in the first side of the oil tank. The oil inlet fluidly communicates with at least one of the plurality of oil passages for returning a mixture of oil and blow-by gases from the at least one of the plurality of oil passages to the oil tank. An angled portion of the second side of the oil tank generally facing the oil inlet is angled relative to a plane defined by the crankshaft axis and the cylinder axis such that the mixture of oil and blow-by gases exiting the oil inlet flow over the angled portion.
In a further aspect, a blow-by gas outlet fluidly communicates the oil tank with an exterior of the engine.
In an additional aspect, the first side of the oil tank is at least in part an outer wall of the crankcase. The second side of the oil tank is an oil tank enclosure connected to the crankcase.
In a further aspect, an angle between the angled portion of the second side of the oil tank and the plane is between 45 degrees and 80 degrees.
In an additional aspect, an axis normal to the oil inlet is generally perpendicular to the plane.
In yet another aspect, the invention provides an internal combustion engine having a crankcase, a crankshaft disposed in the crankcase, and a cylinder block disposed on the crankcase. The crankshaft defines a crankshaft axis. The cylinder block has at least one cylinder. The at least one cylinder defines a cylinder axis. At least one piston is disposed in the at least one cylinder. The at least one piston is operatively connected to the crankshaft. A cylinder head assembly is connected to the cylinder block. A plurality of oil passages is disposed in at least one of the crankcase, the cylinder block, and the cylinder head assembly. An oil tank is fluidly connected to at least one of the oil passages. The oil tank has a first end portion and a second end portion opposite the first end portion. The first end portion is closer to the cylinder head assembly than the second end portion. An oil outlet is disposed in the second end portion of the oil tank for supplying oil from the oil tank to at least one of the crankcase, the cylinder block, and the cylinder head assembly. An oil inlet is disposed in the oil tank for returning oil from at least one of the crankcase, the cylinder block, and the cylinder head assembly to the oil tank. A blow-by gas outlet is disposed in the first end portion of the oil tank. A blow-by gas passage fluidly communicates the blow-by gas outlet with an exterior of the engine. A first portion of the blow-by gas passage extends from the blow-by gas outlet in a direction generally away from the cylinder head assembly, and a second portion of the blow-by gas passage extends from the first portion of the blow-by gas passage in a direction generally towards the cylinder head assembly, such that when the first end portion of the oil tank is disposed generally vertically above the second end portion of the oil tank, blow-by gases in the oil tank flow sequentially from the oil tank to the blow-by gas outlet, to the first portion of the blow-by gas passage, to the second portion of the blow-by gas passage, and to the exterior of the engine.
In a further aspect, the blow-by gas outlet is disposed generally at a center of a length of the first end portion of the oil tank. The length of the first end portion of the oil tank is generally parallel to the crankshaft axis.
In an additional aspect, the oil inlet is arranged in the oil tank such that when the first end portion of the oil tank is disposed generally vertically below the second end portion of the oil tank, blow-by gases in the oil tank flow sequentially from the oil tank to the oil inlet, and to the exterior of the engine.
In a further aspect, the oil inlet returns oil from the cylinder head assembly. When the first end portion of the oil tank is disposed generally vertically below the second end portion of the oil tank, blow-by gases in the oil tank flow to the cylinder head assembly prior to flowing to the exterior of the engine.
In an additional aspect, the oil inlet is a first oil inlet. The engine also has a second oil inlet in the oil tank for returning oil from at least one other of the crankcase, the cylinder block, and the cylinder head assembly to the oil tank. The first and second oil inlets are disposed between the blow-by gas outlet and the oil outlet in a direction generally parallel to the cylinder axis. The first oil inlet is disposed closer than the second oil inlet to the blow-by gas outlet.
In a further aspect, at least one oil pumps oil from at least one of the crankcase and the cylinder block to the oil tank. The first oil inlet returns oil from the at least one oil pump. The second oil inlet returns oil from the cylinder head assembly.
In an additional aspect, the first portion of the blow-by gas passage extends in the crankcase. The second portion of the blow-by gas passage is a timing chain case of the engine fluidly communicating with the cylinder head assembly. When the first end portion of the oil tank is disposed generally vertically above the second end portion of the oil tank, blow-by gases in the oil tank flow to the cylinder head assembly prior to flowing to the exterior of the engine.
In a further aspect, when the first end portion of the oil tank is disposed generally vertically above the second end portion of the oil tank, blow-by gases in the oil tank flow to the cylinder head assembly prior to flowing to the exterior of the engine. The engine also has a blow-by gas separator disposed in the cylinder head assembly for separating oil from the blow-by gases prior to the blow-by gases flowing to the exterior of the engine.
In an additional aspect, the oil tank is formed by an outer wall of the crankcase and by an oil tank enclosure connected to the crankcase.
Embodiments of the present invention each have at least one of the above-mentioned objects and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present invention that have resulted from attempting to attain the above-mentioned objects may not satisfy these objects and/or may satisfy other objects not specifically recited herein.
Additional and/or alternative features, aspects, and advantages of embodiments of the present invention will become apparent from the following description, the accompanying drawings, and the appended claims.
For a better understanding of the present invention, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:
Although the engine 10 of the present invention is being described herein as being usable in a personal watercraft or a snowmobile, it should be understood that it would also be possible to use this engine in other applications, such as, for example, all-terrain vehicles and motorcycles.
As can be seen in
A piston 24 (
Air is supplied to each cylinder 20 by an air intake system (
The engine 10 is mounted to a vehicle via engine mount brackets 41 (some of which are not shown in
As would be understood by a person skilled in the art, the engine 10 is provided with many other components and systems, such as a fuel system, a cooling system, an electrical system and their respective components. U.S. patent application Ser. No. 11/960,566 (the '566 application), filed Dec. 19, 2007, the entirety of which is incorporated herein, provides a description of other components and systems which could be incorporated in the engine 10. The '566 application also provides additional detail as to the construction and features of some of the components and systems described above and below.
Turning now to
From the oil pressure pump 44, the oil flows through an oil filter 48. The oil filter 48 filters out debris and impurities from the oil. An oil filter bypass valve (not shown) may be provided. The oil filter bypass valve would open if oil pressure builds up at the inlet of the oil filter 48, such as if the oil filter 48 becomes clogged, thus permitting oil to continue to flow inside the lubrication system. It is contemplated that the oil filter bypass valve could be integrated with the oil filter 48. The oil then flows to an oil cooler 50. It is contemplated that it may not be necessary to include the oil cooler 50.
From the oil cooler 50 (or the oil filter 48 should the oil cooler be omitted), the oil flows to the main oil gallery 52, and from there it gets separated into two main paths 54, 56. An oil pressure sensor 55 senses the pressure of the oil in the first main path 54 to determine whether the lubrication system is operating properly. The oil flowing through the first main path 54 first lubricates a chain tensioner 58. The chain tensioner 58 is used to tension the timing chain driving the camshafts from the crankshaft 26 as described in the '566 application. The timing chain is disposed in a timing chain case 60 (
From the chain tensioner 58, the oil flowing inside the cylinder head assembly 16 from the first main path 54 lubricates the bearings 40 of the two camshafts. Some of the oil flowing inside the cylinder head assembly 16 is also sprayed on the mechanism used to actuate the intake and exhaust valves. From the cylinder head assembly 16 some of the oil flows back to the oil tank 18 via passage 64 and enters the oil tank 18 via oil inlet 65 (see
A portion of the oil flowing through the second main path 56 is used to lubricate the bearings 31 of the crankshaft 26. The bearing 32 of the crankshaft 26 is lubricated by oil flowing from the leftmost bearing 31 (as shown in
Another portion of the oil flowing through the second main path 56 is sprayed inside the crankcase 12 so as to spray the bottom of the pistons 24. By doing this, the oil both cools the pistons 24 and lubricates the piston pins (not shown). The oil then falls down to the bottom of the crankcase 12 and then to the collecting tanks 70.
The oil which flows inside the ignition case 68 from various sources as described above, and the oil in the collecting tanks 70 flows through the oil sieve 74, and is pumped by the oil evacuation pump 76. The oil evacuation pump 76 is preferably an internal gear pump disposed in the crankcase 12 and driven by the crankshaft 26.
The oil which flows inside the chamber 66 from various sources as described above, flows through oil sieve 78 and is pumped by the oil suction pump 80. The oil suction pump 80 is preferably an internal gear pump disposed in the crankcase and driven by the crankshaft 26.
From the oil pumps 76 and 80 oil flows back to the oil tank 18 via passage 82 and a majority thereof enters the oil tank 18 via oil inlet 84 (see
In the crankcase 12, the blow-by gases mix with the oil droplets. The mixture of blow-by gases and oil droplets present in the crankcase 12 is pumped along with the oil by the evacuation pump 76 back to oil tank 18. As described in greater detail below, once in the oil tank 18, the blow-by gases are separated from the oil. As is also described in greater detail below, when the oil tank 18 is oriented as shown in
Turning now to
The oil tank 18 is filled with oil via an oil tank filler neck 104 on the top of the oil tank enclosure 98 (
As can be seen in
As can be seen in
As can be seen in
As can be seen in
When the blow-by gas outlet 90 is opened, blow-by gases in the oil tank 18 flows in the tortuous blow-by gas passage 122 via the blow-by gas outlet 90. From the tortuous blow-by gas passage 122, blow-by gases flow away from the cylinder head assembly 16 in the blow-by gas passage 92. As seen in
The oil inlet 65 is positioned in the oil tank 18 such that when the blow-by gas outlet 90 is below the oil level, the oil inlet 65 is disposed above the oil level. As an example, when the engine 10 is arranged such that the crankshaft 26 is generally vertical (with the chain case 60 now located at the top of the engine), the blow-by gas outlet 90 is disposed below the oil level (i.e. to the right of oil level line 126 as viewed in
Modifications and improvements to the above-described embodiments of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP08/58336 | 6/27/2008 | WO | 00 | 12/7/2010 |