, Description:MAIN BEARING CAP WITH PRECISELY REPOSITIONING STRUCTURE
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a main bearing cap of cylindrical block of internal combustion engine in vehicles, and, in particular, to a main bearing cap which precisely fitted and refitted onto the cylindrical block to form a bore with half semicircular bore of the main bearing cap and half semicircular bore of the cylindrical block. More particularly, the present subject matter relates to structure of a main bearing cap having two semi-cylindrical bosses at two lateral sides for providing precise relocation of the main bearing cap relative to the cylindrical block. Further, the two semi-cylindrical bosses fit in cylindrical block sides having semi circular machined cavity corresponding to semi-cylindrical bosses for fitting and repositioning of the main bearing cap. BACKGROUND AND PRIOR ART:
[002] Generally, main bearing cap are used for assembly of crankshaft with cylindrical block. For example, the main bearing cap of an engine bolts to a bulkhead of the engine crankcase and together with the bulkhead retains and locates the crankshaft journal in place while the crankshaft is rotating. The crankshaft journal runs against two half shell bearings which are fitted to the main bearing cap and the engine bulkhead semi-circular bores, respectively.
[003] In this case, for vibration free, low friction and quiet running, the roundness of the bore produced by the main bearing cap and the bulkhead of the cylindrical block is important. The roundness of the bore is achieved by a machining operation called line boring. The main bearing caps are bolted to the bulkheads of the cylinder block, and then a boring bar fitted with a cutting tool is used to machine the bores in the assembly. This ensures the two half rounds formed by the main bearing cap and the bearing block form as near to a perfect circle as possible. A finishing operation involving a grinding hone is often used to achieve the extremely fine tolerances needed for quiet running and efficient engine performance.
[004] In order to install the crankshaft, it is necessary to remove the main bearing caps from the cylinder block. After the crankshaft is put in place, it is necessary to reposition the main bearing caps to the bulkhead so that they are replaced in the identical position they occupied during the line boring operation. Any deviation from that original position produces an out-of-round condition that, in turn, leads to vibration, noise and possibly stiff, high friction crankshaft operation.
[005] In order to assemble or attaching the main bearing caps with the cylinder head a number of ways are available when installing the crankshaft. In one known method to locate and reposition the main bearing cap, two hollow dowel pins are used. These dowel pins are pressed into counter-bored holes in the cylinder block bulkhead. The dowel pins then locate in precisely machined counter bores in the corresponding main bearing cap foot sections. The accuracy of installation of the hollow dowel pin is dependent upon the precision counter boring of the cylinder/engine block and the main bearing cap. Both of these operations have a finite tolerance which, when stacked up with the tolerance on the dowel pin outer diameter, can produce an unacceptable variation in location of the main bearing cap. Additionally, this procedure has the added expense of purchasing precision hollow dowel pins, their handling and installation, and the costly machining of precision bores in the bulkhead of the cylinder block and in the main bearing caps.
[006] In another known method, single hollow dowel pin is used with main bearing cap side face interference fit. This method is also expensive and, in fact, can produce a situation where the interference fits between the snap-width and cylinder block are in conflict with the interference fits between the hollow dowel pin and the main bearing cap.
[007] In yet another known method, a protrusion is provided near the main bearing cap bolt holes at foot surface of the main bearing cap. This method also suffers from accuracy and precision. Further, this method does not provide any counter bore in the cylinder head for locating and repositioning of the main bearing cap in the cylinder block. Therefore, there are high possibilities of error during assembly.
[008] Chinese patent publication CN101680484B titled, “Powder metal bearing cap breathing windows” discloses an main bearing cap, and its precursor compact, with an undercut breathing window that is formed during a compaction process. By fabricating the undercut during the compaction process, the invention eliminates the need for a secondary machining operation to form the undercut feature in the bearing caps. This method does not provide solution for the precise repositioning of the main bearing cap.
[009] Hence there is need for a technical solution which can locate main bearing caps precisely with its relative cylinder block without the implementation of excessive force and with a reduction in the occurrence of foot fretting. The technical solution for the main bearing cap should be inexpensive, reliable, simple in manufacturing, and easy to implement. Accordingly, the present invention provides a technical solution by satisfying all the requirements for precise repositioning of the main bearing cap.
OBJECTS OF THE INVENTION:
[0010] The principal objective of the present invention is to provide a main bearing cap for precise repositioning on cylinder block.
[0011] Another object of the present subject matter is to provide a main bearing cap with two semi-cylindrical bosses for precise repositioning.
[0012] Another object of the present subject matter is to provide a main bearing cap with two semi-cylindrical bosses having a plurality of linear tapered protrusions which plastically deform along with the cylinder block during assembly of the main bearing cap to the cylinder block.
[0013] Yet another object of the present subject matter is to provide two semi-circular counter bores on the cylinder head corresponding to the semi-cylindrical bosses for conforming assembly of the main bearing cap with the cylinder block.
[0014] Yet another object of the present subject matter is to provide a simple, effective, and cost efficient structure of main bearing cap with precise repositioning structure for assembly of the main bearing cap with the cylinder block.
SUMMARY OF THE INVENTION:
[0015] The subject matter herein relates to a main bearing cap for precise repositioning with cylinder block to define a bearing bore between the main bearing cap and the cylinder bock. The main bearing cap has two foot portions which are joined by a bridge portion. A bolt hole extends through each of the foot portion from top to bottom the main bearing cap. Further, two semi-cylindrical bosses are formed on lateral sides of the foot portions of the main bearing cap. One semi-cylindrical boss is formed on one lateral side of the foot portion and other on the other lateral side of the other foot portion of the main bearing cap. Further, the semi-cylindrical boss has a plurality of linear tapered protrusions angularly spaced apart all the way around circumference of the semi-cylindrical boss upto surface of the lateral side of the main bearing cap. The plurality of linear tapered protrusions is pointed towards end. Further, the plurality of linear tapered protrusion is equally angularly spaced apart from each other. The plurality of linear tapered protrusions is ductile in nature which can easily plastically deforms while conforming to the semi circular counter bore of the cylinder block. The plastic deformation of the plurality of linear tapered protrusions allows repeated repositioning of the main bearing cap on the cylinder block during assembly of crank shaft in the engine.
[0016] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0018] Fig. 1 illustrates structure of cylinder block with main bearing cap, in accordance with an embodiment of the present subject matter;
[0019] Fig. 2 illustrates structure of the main bearing cap with two semi-cylindrical boss, in accordance with an embodiment of the present subject matter;
[0020] Fig. 3 illustrates isometric view of the main bearing cap, in accordance with an embodiment of the present subject matter;
[0021] Fig. 4 illustrates side view of the main bearing cap, in accordance with an embodiment of the present subject matter;
[0022] Fig. 5 illustrates front side view of the main bearing cap, in accordance with an embodiment of the present subject matter;
[0023] Fig. 6 illustrates top and detailed view of the semi-cylindrical boss of the main bearing cap, in accordance with an embodiment of the present subject matter;
[0024] Fig. 7 illustrates structure of the cylinder block having two semi-circular counter bores/cavity to receive the main bearing cap, in accordance with an embodiment of the present subject matter; and
[0025] Fig. 8 illustrates assembly of the main bearing cap with the cylinder block, in accordance with an embodiment of the present subject matter.
[0026] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0027] The subject matter herein relates to a main bearing cap for precise repositioning with cylinder block to define a bearing bore between the main bearing cap and the cylinder bock. The main bearing cap has two foot portions which are joined by a bridge portion. A bolt hole extends through each of the foot portion from top to bottom the main bearing cap. Further, two semi-cylindrical bosses are formed on lateral sides of the foot portions of the main bearing cap. One semi-cylindrical boss is formed on one lateral side of the foot portion and other on the other lateral side of the other foot portion of the main bearing cap. Further, the semi-cylindrical boss has a plurality of linear tapered protrusions angularly spaced apart all the way around circumference of the semi-cylindrical boss upto surface of the lateral side of the main bearing cap. The plurality of linear tapered protrusions is pointed towards end. Further, the plurality of linear tapered protrusion is equally angularly spaced apart from each other. The plurality of linear tapered protrusions is ductile in nature which can easily plastically deforms while conforming to the semi circular counter bore of the cylinder block. The plastic deformation of the plurality of linear tapered protrusions allows repeated repositioning of the main bearing cap on the cylinder block during assembly of crank shaft in the engine.
[0028] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various assembly that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0029] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0030] Fig. 1 illustrates structure of cylinder block with main bearing cap, in accordance with an embodiment of the present subject matter. The assembly of internal combustion engine has cylinder block 101 which has main bearing cap 102 fitted with two bolts 103 on both foot sides.
[0031] Fig. 2 illustrates structure of the main bearing cap with two semi-cylindrical bosses, in accordance with an embodiment of the present subject matter. The main bearing cap 200 defines a semicircular bore 203 which together with the semicircular bore of the cylinder block defines the bore through which the crankshaft of the engine extends and is journaled. Journal bearings may be received in the bore between the surface of the crankshaft and the surface of the bore, as is well known.
[0032] The main bearing cap 200 has two foot portions 201, 202. The semicircular bore 203 defines on each of its lateral sides 206, 207 a foot portion 201, 202 of the main bearing cap 200. Further, a bridge portion 204 joins the two foot portions 201, 202. A bolt hole 205 extends through each foot portion 201, 202 from top to bottom the main bearing cap 200 along the foot portions 201, 202. The bottom side of each foot portion 201, 202 is a flat bottom surface 210 which is co-planar with one another.
[0033] Two semi-cylindrical bosses 208 are formed on lateral sides 206, 207 of the foot portions 201, 202 of the main bearing cap 200. One semi-cylindrical boss 208 is formed on one lateral side 206 of the foot portion 201 of the main bearing cap 200. Similarly, another semi-cylindrical boss 208 is formed on other lateral side 207 of the foot portion 202 of the main bearing cap 200 as shown in the figure 4. Figure 3 illustrates the isometric view of the main bearing cap 200 with semicircular bore 204. The two semi-cylindrical bosses are disposed in middle of the lateral sides 206, 207 of the foot portions 201, 202. Both the semi-cylindrical bosses 208 are identical with each other, so only one will be described in detail. The semi-cylindrical boss 208 extends for 180° on surface of the lateral side. The semi-cylindrical boss 208 has height less than half of the height of the lateral side 206 of the main bearing cap 200. The semi-cylindrical boss 208 extends along height of the lateral side 206.
[0034] Further, the semi-cylindrical boss 208 has a plurality of linear tapered protrusions 209 angularly spaced apart all the way around circumference of the semi-cylindrical boss 208 upto surface of the lateral side 206 of the main bearing cap 200. The plurality of linear tapered protrusions 209 has height ‘h’ less than height of the semi-cylindrical boss 208. Further, the height ‘h’ of the plurality of linear tapered protrusions 209 matches with the height of semi-circular counter bores 301 of the cylinder block 300 as shown in the figure 7. As shown in the figure 6, the plurality of linear tapered protrusions 209 are pointed towards end. Further, the plurality of linear tapered protrusions 209 are equally angularly spaced apart from each other. The plurality of linear tapered protrusions 209 conform to the semi circular counter bore 301 and adjusted accordingly for precise reposition. The plurality of linear tapered protrusions 209 is ductile which can easily plastically deforms while conforming to the semi circular counter bore 301 of the cylinder block 300. The main bearing cap 200 is made of a material that has adequate ductility. The plastic deformation of the plurality of linear tapered protrusions 209 allows repeated repositioning of the main bearing cap 200 on the cylinder block 300 during assembly of crank shaft in the engine.
[0035] As shown in the figure 7, the cylinder block also has semi-circular counter bores 301 to receive the semi-cylindrical bosses 208 of the main bearing cap 200. The semi-circular counter bores 301 are made by machine cutting process. The plurality of linear tapered protrusions 209 has height equal to height of the semi-circular counter bores 301 of the cylinder block 300.
[0036] As shown in figure 8, during assembly of the main bearing cap 200 with the cylinder block 300, the plurality of linear tapered protrusion 209 aids in locating the main bearing cap 200 into the semi-circular counter bores 301 of the cylinder block 300. During assembly of the main bearing cap 200 with the cylinder lock 300, the plurality of linear tapered protrusions 209 plastically deform along with the cylinder block 300 and provide conformance of the main bearing cap 200 with the cylinder block 300. The semi-cylindrical boss plastically conforms to the semi-circular counter bore of the cylinder block to provide precise repositioning. The present assembly enables “perfect repositioning” of the main bearing cap into the cylinder block. Moreover, this can reduce “foot fretting” by locking the part to the block mechanically.
[0037] Generally, the cylinder block is made of aluminum material and main bearing cap is made of sintered powder metal. In one embodiment, the plurality of linear tapered protrusion bite inside the cylinder block because of soft aluminum material of the cylinder block. In another embodiment, the main bearing cap is made of material with adequate ductility. In order to achieve all benefits and advantages of the invention and to apply all technical features of the present invention, the main bearing cap should be made of sintered powder material with adequate ductility.
[0038] As mentioned above, the main bearing cap must be made of sintered powder metal. A desirable quality of the powder metal material of the bearing cap for carrying out the invention is ductility. Since the protrusions yield plastically to some extent during the initial installation process, it is important to avoid cracking. Most powder metal ferrous materials are inherently brittle. To overcome this potential difficulty, it is preferable to use a material that has an adequate ductility. An appropriate liquid phase sintering system is particularly useful in providing the necessary ductility in the sintered powder metal. An example of this process involves the use of a phosphorus compound, such as ferro-phosphorus. A small amount of ferro-phosphorus powder is added to the ferrous material powder during powder blending. As person skilled in the art is well aware about the process for increasing the ductility of the sintered powder metal.
[0039] Among the advantages of using a powder metal process to make the main bearing cap is that the fine features of the semi-cylindrical boss and the plurality of linear tapered protrusions can be formed in the as-compacted preform. This means that little to no finishing work may be required to produce these features, which can save time and money in comparison to other methods of fabrication.
[0040] The term “vehicle” as used throughout this detailed description and in the claims refers to any moving vehicle that is capable of carrying one or more human occupants and is powered by any form of energy. The term “vehicle” is a motor vehicle which includes, but is not limited to: cars, trucks, vans, minivans, hatchback, sedan, MUVs, and SUVs.
[0041] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0042] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

Claims:We claim:
1. A main bearing cap (200) for precise repositioning with cylinder block (300) to define a bearing bore between the main bearing cap (200) and the cylinder bock (300), the main bearing cap (200) comprising:
at least two foot portions (201, 202) provided at lateral side of a semi-circular bore (203);
a bridge portion (04) joins the at least two foot portions (201, 202);
at least one bolt hole extend through each of the foot portions (201, 202) from top side to bottom to mount the main bearing cap (200) on the cylinder block (300);
characterized in that
a semi-cylindrical boss (208) formed on lateral side (206, 207) of each of the foot portion (201, 202) to precisely repositioning of the main bearing cap (200) on the cylinder block (300).

2. The main bearing cap (200) as claimed in claim 1, wherein each of the semi-cylindrical portion (208) has a plurality of linear tapered protrusion (209) which is angularly spaced apart all way round on circumference of the semi-cylindrical portion (208).

3. The main bearing cap (200) as claimed in claim 2, wherein height of the plurality of plurality of linear tapered protrusion (209) matches with height of semi circular counter bore (301) of the cylinder block (300).

4. The main bearing cap (200) as claimed in claim 1, wherein height of each of the semi-cylindrical portion (208) is less than half height of the lateral sides (206, 207).

5. The main bearing cap (200) as claimed in claim 1, wherein the cylinder block (300) has semi-circular counter bore (301) to receive the semi cylindrical boss (208) of the main bearing cap (200).
6. The main bearing cap (200) as claimed in claim 1, wherein the plurality of linear tapered protrusions (209) plastically deform along with diameter of the semi-circular counter bores (301) of cylinder block (300).

7. The main bearing cap (200) as claimed in claim 1, wherein the cylinder block (300) has semi circular counter bores (301) at interference of the edges for receiving the semi cylindrical bosses (208) of the main bearing cap (200).

8. The main bearing cap (200) as claimed in claim 1, wherein the main bearing cap (200) is made of sintering powder material.

9. The main bearing cap (200) as claimed in claim 1, wherein the plurality of linear tapered protrusions (209) plastically conform with the semi circular counter bore (301) of the cylinder block (300).