Oil seal
According to the present invention, a variable compression ratio machine having main bearings mounted in an eccentric carrier or support includes an oil seal located primarily in a main bearing cap for minimizing leakage of pressurized main bearing oil. The seal is located generally in a first main bearing fastener socket or fastener access cutout in order to minimize structurally compromising the bearing cap, and a portion of the fastener socket preferably is used as an oil passageway as well as for wrench access to the fastener. The oil seal and oil circuit of the present invention enable the size of the eccentric support to be minimized while also providing highly effective oil sealing. In more detail, a significant advantage of the present invention is that highly effective oil sealing is attained without compromising the size or structural integrity of the bearing cap. A second significant advantage of the present invention is that it can be manufactured and assembled at low cost. The oil sealing system of the present invention is robust and highly reliable.
This application relates to Provisional Application No. 60/849,314 having a filing date of Oct. 3, 2006.
BACKGROUND OF THE INVENTIONVariable compression ratio can significantly increase the fuel efficiency of reciprocating piston engines used in passenger cars and trucks. The present invention relates to variable compression ratio mechanisms having a crankshaft mounted in eccentric supports, and more specifically to the oil supply circuit used to deliver oil to the main bearings of the crankshaft.
Kurt Imren Yapici shows a variable compression ratio engine in U.S. Pat. No. 6,588,384 issued on Jul. 8, 2003 and assigned to FEV GmbH of Germany. An oil galley that circumnavigates an eccentric support can be seen in
Mendler (the current applicant) shows another variable compression ratio engine in U.S. Pat. No. 6,443,107 issued on Sep. 3, 2002.
Lawrence et al. show a variable compression ratio engine having eccentric main bearing supports in US Patent Application Publication No.: US 2006/0112911 A1, having a publication date of Jun. 1, 2006.
Accordingly, objectives of the present invention are to provide an oil supply circuit for variable compression ratio engines of the eccentric main bearing support type, that provides minimal oil loss and low manufacture and assembly cost. Another objective is to provide a streamline oil flow circuit in order to minimize the oil pump power requirements. Another objective is to provide an oil supply circuit and eccentric support design that is compact and light in design, while also providing rigid support and alignment of the crankshaft main bearings.
SUMMARY OF THE INVENTIONAccording to the present invention, a variable compression ratio machine having main bearings mounted in an eccentric carrier or support includes an oil seal located primarily in a main bearing cap for minimizing leakage of pressurized main bearing oil. The seal is located generally in a first main bearing fastener socket or fastener access cutout in order to minimize structurally compromising the bearing cap, and a portion of the fastener socket preferably is used as an oil passageway as well as for wrench access to the fastener. The oil seal and oil circuit of the present invention enable the size of the eccentric support to be minimized while also providing highly effective oil sealing. In more detail, a significant advantage of the present invention is that highly effective oil sealing is attained without compromising the size or structural integrity of the bearing cap. A second significant advantage of the present invention is that it can be manufactured and assembled at low cost. The oil sealing system of the present invention is robust and highly reliable.
In the preferred embodiment of the present invention the seal includes a boss that nests into the fastener socket, thereby providing a low cost means for retaining or holding the seal in position.
Preferably the seal has a hole through the boss for permitting the oil to flow into the lower portion of the fastener socket. A short oil passageway or eccentric oil feed line is then used to direct oil from the fastener socket to the main bearings. The eccentric oil feed line is relatively short and results in an acceptably small reduction of bearing cap stiffness.
The oil flow circuit is streamline and permits the oil feed pressure to be minimized. The low feed pressure and the effective sealing means according to the present invention enables oil pump power to be minimized and engine efficiency maximized. The oil seal is highly reliable and has a low manufacturing and assembly cost.
The eccentric support includes a bearing cap 22 and a plurality of fasteners 24 for retaining the crankshaft in the eccentric support.
According to the present invention, the eccentric support further includes a first fastener access cutout 26. According to the preferred embodiment of the present invention, eccentric support 16 also includes an oil seal 28 located primarily in the region of the first access cutout 26.
Bearing cap 22 further including a bearing socket 30 for retaining one or more of the main bearings 20 in eccentric support 16.
Housing 4 includes at least one housing oil feed line 32. Housing oil feed line 32 has an upstream end 34, the upstream end being in fluid communication with oil supply 2, and a down stream end 36, the down stream end being in fluid communication with first fastener access cutout 26.
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Arrow 44, including upper and lower arrow segments, is intended to illustrate the primary oil flow pathway of the bearing oil. Primary oil flow pathway 44 extends from oil supply 2 to main bearings 20. Primary oil flow pathway 44 including a first pathway section 45 extending from oil supply 2 to first fastener access cutout 26, and a second pathway section 47 extending from first fastener access cutout 26 to main bearings 20. According to the preferred embodiment of the present invention, the oil primarily flows directly out of the first pathway section 45 into the second pathway section 47, with the junction of the two pathways being located within the first fastener access cutout.
Eccentric support 16 has an outer bearing surface 46 having an outer circumference 48 for pivotably supporting eccentric support 16 in housing 4. A small clearance gap 49 separates bearing surface 46 from housing 4.
According to the present invention, the oil circuit further has a sealing curtain area 43 around first fastener access cutout 26. The preferred embodiment of the present invention includes sealing means for providing a small sealing curtain area 43 through which oil can leak from the oil flow pathway 44. In more detail, the present invention includes sealing means for minimizing oil leakage between the housing oil feed line 32 and eccentric oil feed line 38. The sealing curtain area 43 is generally the product of the average or approximate radial clearance gap 49 between the eccentric outer bearing surface including the sealing means and the housing 4 around curtain 43, and the minimum perimeter length around oil flow pathway 44 at the interface of the outer bearing surface 46 and housing 4. In more detail sealing curtain area 43 is generally the smallest imaginary surface that if it was impermeable, would seal the clearance gap between the housing oil feed line 32 and the eccentric oil feed line 38 and stop oil leakage. In the preferred embodiment of the present invention, oil seal 28 forms a seal with housing 4 for minimizing the oil sealing curtain area 43, and thereby minimizing oil leakage. With respect to location of oil seal 28, the sealing function is preferably primarily located in or generally in the first fastener access cutout in order to minimize the length of the sealed perimeter and in turn minimize curtain area. Preferably oil seal 28 is located in first fastener access cutout 26, although the sealing means may extend outside of first fastener cutout 26 in some embodiments of the present invention.
According to the present invention, oil supply 2 is in fluid communication with first fastener access cutout 26 through housing oil feed line 32, and first fastener access cutout 26 is in fluid communication with main bearings 20 through eccentric oil feed line 38, thereby providing an oil supply circuit for delivering oil from oil supply 2 to the main bearings 20 with minimal oil leakage.
Preferably, according to the present invention, the downstream end of the housing oil feed line 36 is directly or almost directly aligned with first fastener access cutout 26 at all compression ratio settings, to provide streamlined flow of oil from the first pathway section 45 into the second pathway section 47, for reducing the required oil pressure of the lubrication system.
Bearing cap 22 has a first fastener 50, and first fastener 50 has a first fastener line of action 52. First fastener 50 has a first fastener head 54 having an approximate first fastener head circumference 56. Those skilled in the art will appreciate that various types of fastener heads may be used according to the present invention. First fastener head circumference 56 and line of action 52 define an imaginary cylinder 58. According to the preferred embodiment of the present invention, first fastener access cutout 26 includes at least the region inside imaginary cylinder 58 and inside outer circumference 48 that can be occupied with oil that is freely in fluid communication with main bearings 20. In embodiments of the present invention including a seal such as oil seal 28, first fastener access cutout 26 also refers to the region inside seal 28. In the preferred embodiment of the present invention, first fastener access cutout 26 extends slightly outside 27 of imaginary cylinder 58. According to the preferred embodiment of the present invention, the oil circuit passes through first fastener access cutout 26, and in more detail eccentric oil feed line 38 and second pathway 47 do not bypass first fastener access cutout 26.
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Oil seal 28 is intended to substantively minimizing leakage of oil between housing oil feed line 32 and eccentric oil feed line 38. Those skilled in the art will appreciate that various types and shapes of sealing means can be used according to the present invention.
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In the embodiment of the present invention shown in
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Preferably according to the present invention, connecting rod 14 advances from the region adjacent to minor half 82 of bearing cap 22 to the region adjacent to major half 84 of said bearing cap 22, thereby providing a crankshaft rotational direction yielding an eccentric support that is stiff and compact while also having a first fastener access cutout and an eccentric oil feed line drilled hole that can weaken the part due to removed metal. According to the preferred embodiment of the present invention, the downstream end 42 of flow pathway 47 introduces oil to the crankshaft main bearings 20 slightly after piston 8 reaches its highest location in cylinder 6, thereby providing optimum lubrication of main bearings 20 and crankshaft 10.
Claims
1. An oil circuit for a variable compression ratio mechanism having a range of compression ratio settings, and having an oil supply, a housing and at least one cylinder mounted in the housing, a piston mounted for reciprocating movement in the cylinder, a crankshaft defining an axis about which the crankshaft rotates, and a connecting rod connecting the piston to the crankshaft, said variable compression ratio mechanism further having at least one eccentric support for supporting the crankshaft about the rotational axis of the crankshaft, the eccentric support being mounted in the housing for pivoting relative to the housing about a pivot axis, the pivot axis being substantially parallel to and spaced from the rotational axis of the crankshaft, and main bearings mounted in the eccentric support for supporting the crankshaft,
- said eccentric support further including a bearing cap and a plurality of fasteners for retaining the crankshaft in the eccentric support, said bearing cap further including a bearing socket for retaining one or more of said main bearings in the eccentric support,
- said eccentric support further having a first fastener access cutout,
- a housing oil feed line in said housing, said housing oil feed line having an upstream end, said upstream end being in fluid communication with the oil supply, and a down stream end, said down stream end being in fluid communication with said first fastener access cutout,
- wherein said oil circuit further has an eccentric oil feed line in said eccentric support, said eccentric oil feed line having an upstream end, said upstream end being connected to said first fastener access cutout, and a down stream end, said down stream end being in fluid communication with said main bearings,
- wherein said oil supply is in fluid communication with said first fastener access cutout through said housing oil feed line, and said first fastener access cutout is in fluid communication with said main bearings through said eccentric oil feed line,
- wherein said oil circuit further has a sealing curtain area around said first fastener access cutout, and sealing means for providing a small curtain area for providing minimal oil leakage between said housing oil feed line and said eccentric oil feed line, thereby providing an oil supply circuit for delivering oil from the oil supply to the main bearings with minimal oil leakage.
2. The oil circuit of claim 1 further including an oil seal for substantively minimizing leakage of oil between the housing oil feed line and the eccentric oil feed line, said seal being mounted on said eccentric support.
3. The oil circuit of claim 1 further including an oil seal for substantively minimizing leakage of oil between the housing oil feed line and the eccentric oil feed line, said seal being located generally in said first fastener access cutout.
4. The oil circuit of claim 3, wherein said first fastener access cutout includes retaining means for retaining said oil seal in location.
5. The oil circuit of claim 3, further having a first fastener socket, and said oil seal further includes a boss, said boss being positioned in said first fastener socket for retaining said oil seal in position for oil sealing.
6. The oil circuit of claim 5, wherein the upstream end of said eccentric oil feed line is in fluid communication with said first fastener socket, and said boss has a cutaway section to permit flow of oil from the housing oil feed line to the eccentric oil feed line,
- said upstream end of said housing oil feed line being in fluid communication with the oil supply, and said down stream end of said housing oil feed line being in fluid communication with said first fastener socket,
- said upstream end of said eccentric oil feed line being in fluid communication with said first fastener socket, and said down stream end of said eccentric oil feed line being in fluid communication with said main bearings,
- wherein said oil supply is in fluid communication with said first fastener socket through said housing oil feed line, and said first fastener socket is in fluid communication with said main bearings through said eccentric oil feed line, thereby providing an oil supply circuit for delivering oil from the oil supply to the main bearings.
7. The oil circuit of claim 1, further having a first fastener socket,
- wherein said oil circuit has a primary oil flow pathway from said oil supply to said main bearings at all of said compression ratio settings, said primary oil flow pathway including a first pathway section from said oil supply to said first fastener socket and a second pathway section from said fastener socket to said main bearings, thereby providing a streamline flow passageway with minimal pressure loss.
8. The oil circuit of claim 5, wherein the upstream end of said eccentric oil feed line bypasses said first fastener socket.
9. The oil circuit of claim 2 wherein said oil seal is made out of a compressive material for provide seating contact between said oil seal and said housing.
10. The oil circuit of claim 2 further including a spring for providing sealing contact between said oil seal and said housing.
11. The oil circuit of claim 10 wherein said spring is located in said first fastener socket for providing sealing contact between said oil seat and said housing.
12. The oil circuit of claim 1, where in said first fastener access cutout is located in said bearing cap.
13. The oil circuit of claim 1, further including eccentric support outer bearings, and bleed holes for release of oil from the oil supply circuit for lubricating the eccentric support outer bearings.
14. The oil circuit of claim 12, wherein said bearing cap has a parting surface and a normal imaginary plane, said normal imaginary plane being normal to said parting surface, the rotational axis of the crankshaft being entirely within said imaginary plane,
- said bearing cap having a minor half located on one side of said normal imaginary plane, and a major half located on the other side of said normal imaginary plane, said major half of said bearing cap being generally larger than said minor half of said bearing cap,
- wherein said first fastener access cutout is located in said major half of said bearing cap, for providing both a small eccentric support and a first fastener access cutout long enough for an open oil circuit at all compression ratio settings.
15. The oil circuit of claim 14, wherein said connecting rod advances from the region adjacent to said minor half of said bearing cap to the region adjacent to said major half of said bearing cap, thereby providing a crankshaft rotational direction yielding an eccentric support that is stiff and compact while also having a first fastener access cutout and an eccentric oil feed line drilled hole.
16. The oil circuit of claim 1 wherein said sealing means includes a small curtain area circumference and a small assembly tolerance between said housing and said outer bearing surface.
17. The oil circuit of claim 1, further having a first compression ratio setting, a first fastener line of action and a first flow stream segment, said flow stream segment being generally aligned with said first fastener line of action at said first compression ratio setting.
18. The oil circuit of claim 17, further including an oil seal for substantively minimizing leakage of oil between the housing oil feed line and the eccentric oil feed line, wherein said first flow stream segment passes through said oil seal.
19. The oil circuit of claim 1, further having a first fastener socket, wherein said eccentric oil feed line is connected to said first fastener socket downstream of said first fastener access cutout.
Type: Application
Filed: Sep 25, 2007
Publication Date: Jan 14, 2010
Inventor: Edward Charles Mendler (Mill Valley, CA)
Application Number: 12/311,561
International Classification: F01M 11/02 (20060101);