JP4548399B2 - Crankshaft support structure and crankshaft support method for internal combustion engine - Google Patents

Description

  The present invention relates to a crankshaft support structure and a crankshaft support method for an internal combustion engine having a configuration in which a crankshaft is supported by using a crankcap as a bearing member assembled to a cylinder block.

In general, for example, in a multi-cylinder internal combustion engine for automobiles, as a crankshaft support structure, a crank cap (also referred to as a bearing cap or the like) forms a bearing portion between the cylinder block, and a crank portion is formed by the bearing portion. Some configurations support the shaft. Specifically, the semicircular bearing surfaces formed on the bulkhead and the crankcap are fixed to each other by fixing the crankcap to the bulkhead (partition wall) provided between the cylinders in the cylinder block. Thus, a shaft hole as a bearing portion is formed. The crankshaft is supported by the crank journal (main shaft portion) of the crankshaft being supported in the shaft hole via a crank bearing (also referred to as bearing metal or the like).
Thus, in the configuration in which the crankshaft is supported by using the crankcap, the crankcap that supports the crankshaft between the cylinder block and the cylinder block has a mating surface with respect to the crankcap of the cylinder block and There exists a structure which contact | connects in the both sides | surfaces which form a recessed part with this mating surface (for example, refer patent document 1).

A conventional crankshaft support structure will be described with reference to FIG. FIG. 6 is a partial sectional view showing a conventional crankshaft support structure.
As shown in FIG. 6, in a configuration in which a crank cap 120 that supports the crankshaft 101 is used between the cylinder block 110 and the crankshaft 101 is supported, the bulkhead 111 provided between the cylinders in the cylinder block 110 The crank cap 120 is fitted into the recess 112 formed below. The crank cap 120 fitted in the recess 112 is fastened and fixed to the cylinder block 110 by a stud bolt 127 that penetrates the crank cap 120 in the vertical direction.

The concave portion 112 into which the crank cap 120 is fitted is formed in a lower portion of the bulkhead 111, a mating surface 113 of the cylinder block 110 with respect to the crank cap 120, and a skirt that protrudes laterally on the lower portion of the cylinder block 110. It is formed from side surfaces 114 and 114 which are inner side surfaces of the portions 115 and 115.
Then, a semicircular bearing surface 116 is formed at a substantially central portion on the left and right sides of the bulkhead 111, and the semicircular bearing surface 126 is also formed on the crank cap 120 side so as to face the bearing surface 116 on the cylinder block 110 side. Is formed. Thus, a shaft hole (bearing portion) is formed by the bearing surfaces 116 and 126 with the crank cap 120 fitted in the recess 112 of the cylinder block 110. The journal shaft 101a of the crankshaft 101 is supported in the shaft hole via the upper bearing 118 and the lower bearing 128 each having a semicircular shape and along the bearing surfaces 116 and 126. Supported. Oil (lubricating oil) is interposed between the bearings 118 and 128 and the crankshaft 101.

As described above, conventionally, the following method is used for positioning the crank cap used to support the crankshaft.
That is, as described above, the crank cap is fitted into the recess formed below the bulkhead of the cylinder block by press fitting, and is positioned by being fixed to the bulkhead by a fastener such as a bolt. As a fastener for fixing the crank cap, for example, as described above, a stud bolt that penetrates the crank cap in the vertical direction or a skirt portion of the cylinder block that penetrates the crank block in an oblique direction or a horizontal direction from the outer side thereof is used. A side bolt or the like screwed into the cap is used.

In addition, there is a method in which a ladder frame in which a crank cap is cast is used for positioning the crank cap. A ladder frame (also referred to as a lower case) includes left and right side walls along the left and right sides of the cylinder block, and a partition wall that is perpendicular to the side wall and is installed at a position corresponding to the bulkhead of the cylinder block And a crankshaft that supports the crankshaft together with the cylinder block in a state assembled to the cylinder block. That is, a plurality of crank caps are cast into each partition wall portion of the ladder frame, and are integrated in a state of being positioned in advance with respect to each bulk head and assembled to the cylinder block.
JP-A-5-195870

  Incidentally, in a configuration in which a crank cap is used and a crank shaft is supported, generally, co-processing is performed on a bearing portion in a state where the crank cap is assembled to a cylinder block. That is, first, the crank cap is assembled by being fixed to the cylinder block with a bolt or the like without incorporating the crankshaft. In a state where the crank cap is assembled, the shaft hole (bearing portion) formed by the cylinder block and the crank cap is subjected to co-working by processing such as honing. Roundness is obtained. Then, after the co-processing, the crank cap is once removed from the cylinder block and reassembled to the cylinder block in a state of supporting the crankshaft with the crankshaft being assembled.

As described above, when co-working with the crank cap assembled to the cylinder block and re-assembly of the crank cap with the crankshaft being incorporated, the conventional crank cap configuration and its positioning method are commonly used. At the time of machining, a step may occur on the mating surface between the cylinder block and the crank cap after reassembly in the shaft hole having a predetermined roundness.
Such a step on the mating surface between the cylinder block and the crank cap (hereinafter simply referred to as “step on the mating surface”) causes turbulence in the oil around the crankshaft as the crankshaft rotates during actual operation of the internal combustion engine. Causing friction to increase. Such an increase in friction causes a limitation on the output of the internal combustion engine, a decrease in fuel consumption, and the like.

  That is, as described above, in the configuration in which the crank cap is press-fitted into the recess formed in the cylinder block, the crank cap once press-fitted is removed when the crankshaft is assembled (reassembled). For this reason, when the crank cap is press-fitted or removed, the press-fitting allowance is cut off, and the amount of the press-fitting allowance cut off causes play in the reattached state of the crank cap. The play that occurs between the cylinder block and the crank cap causes a step in the mating surface.

Further, in the configuration in which the crank cap is cast into the ladder frame, the ladder frame is provided with a knock pin for alignment with the cylinder block. That is, when the ladder frame is assembled to the cylinder block, the knock pin is fitted into the pin hole provided at a predetermined position of the cylinder block.
A predetermined clearance exists between the knock pin of the ladder frame and the pin hole of the cylinder block. For this reason, when the ladder frame is assembled to the cylinder block in a state of being shifted by the clearance, a step on the mating surface may occur.

Further, the level difference of the mating surfaces tends to increase during actual operation of the internal combustion engine due to the configuration of the crank cap, which also causes a friction increase.
In general, the cylinder block and the crank cap are made of different materials, for example, the cylinder block is made of an aluminum-based material such as an aluminum alloy, and the crank cap is made of an iron-based material such as cast iron. For this reason, during actual operation of the internal combustion engine, the temperature rises and a difference in thermal expansion occurs between the cylinder block and the crank cap, and the step of the mating surface is emphasized in the configuration of the conventional crank cap.

The step of the mating surface will be specifically described with reference to FIG. FIG. 7 is an explanatory view showing the level difference of the mating surface in the conventional crankshaft support structure.
As shown in FIG. 7, when the cylinder block 110 and the crank cap 120 are deformed due to thermal expansion during actual operation of the internal combustion engine, for example, when the cylinder block 110 is larger, the bearing surface 116 on the cylinder block 110 side is closer to the crank cap 120 side. The bearing surface 126 is expanded. Therefore, the upper bearing 118 provided along the bearing surface 116 on the cylinder block 110 side follows the deformation of the bearing surface 116, and the lower bearing 128 provided along the bearing surface 126 on the crank cap 120 side is provided on the bearing surface 126. Follow the deformation. For this reason, the level | step difference 150 from which the crank cap 120 side protrudes inward arises in the mating surface including both the bearings 118 and 128. FIG. 7 shows a state in which a step 150 is generated on both the left and right sides of the crankshaft 101. The step 150 on the mating surface causes an increase in friction by causing turbulence in the oil 105 around the crankshaft 101 as the crankshaft 101 rotates.
7 is actually very small in comparison with the size of the shaft hole formed by the bearing surfaces 116 and 126, but is exaggerated for convenience of explanation.

The step 150 emphasized by the difference in thermal expansion between the cylinder block 110 and the crank cap 120 is caused by the configuration of the conventional crank cap 120 as described above.
That is, conventionally, in the recess 112 formed by the mating surface 113 of the cylinder block 110 and the both side surfaces 114 which are the inner surfaces of the skirt portion 115, the integral crank cap 120 has a bearing surface 126 with respect to the cylinder block 110. And fixed by a stud bolt 127 or the like disposed on the left and right. For this reason, the crank cap 120 stretches (or pulls) the fastening portion in accordance with the deformation due to the thermal expansion, and there is no escape space for the recessed portion 112 of the expanded portion of the crank cap 120. For this reason, the wrinkles of deformation of the cylinder block 110 and the crank cap 120 appear in a roundness, and the step 150 of the mating surface is emphasized.
In addition, since the left and right portions of the crank cap 120 through the bearing surface 126 are integrated (connected), deformation due to thermal expansion interferes with each other at the left and right portions. Therefore, when the crank cap 120 is assembled so as to eliminate one of the left and right steps 150, the step 150 is generated on the left and right sides due to the difference in thermal expansion with the cylinder block 110.

  As described above, in the configuration of the conventional crank cap and the positioning method thereof, there is a case where a step of the mating surface that causes an increase in friction occurs in the rotation of the crankshaft, particularly when the internal combustion engine is actually operated (at a high temperature). .

  Therefore, the problem to be solved by the present invention is to absorb the influence of the thermal expansion difference between the cylinder block and the crank cap in a configuration in which a crank cap is used as a bearing member assembled to the cylinder block and the crank shaft is supported. Even when the internal combustion engine is in operation, the step generated on the mating surface between the cylinder block and the crank cap can be eliminated, and the friction caused by the rotation of the crankshaft can be reduced. An object of the present invention is to provide a crankshaft support structure for an internal combustion engine and a method for manufacturing the internal combustion engine.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, the bearing member that is assembled to the cylinder block and supports the crankshaft together with the bearing surface that is formed on the cylinder block, the mating surface of the cylinder block with respect to the bearing member and the mating of the cylinder block A crankshaft support structure for an internal combustion engine configured to be in contact with both sides forming a recess together with a surface, wherein the bearing member is composed of two divided elements divided in the direction of the both sides, and each divided element In a state where the cylinder block is assembled to the cylinder block, there is a gap between the end faces facing each other at least so that the end faces do not contact each other in an actual use environment of the internal combustion engine.

  In Claim 2, The engagement surface which gives a wedge effect | action to the said division | segmentation element with each side surface which forms the said recessed part with each side part via the said bearing surface in the mating surface of the said cylinder block An engaging surface that receives the wedge action together with the side surface of each of the divided elements that engages with the engaging portion and contacts each of the side surfaces, on the mating surface of each divided element with respect to the cylinder block The engaging part which has is provided.

  According to a third aspect of the present invention, at least a part of a portion of the bearing member that forms the bearing surface is provided with an overlapping portion in which the dividing elements overlap with each other in the axial direction of the crankshaft.

  In Claim 4, A crankshaft is supported with the bearing surface of this cylinder block assembled | attached to a cylinder block, The both sides which form a recessed part with the mating surface with respect to the said bearing member of this cylinder block, and this mating surface with respect to a cylinder block The bearing member is attached to the cylinder block without assembling the crankshaft, and the bearing portion of the crankshaft is co-processed, and then the bearing member is temporarily removed from the cylinder block, A method for supporting a crankshaft of an internal combustion engine in which a bearing member is reassembled to a cylinder block with the incorporation of a crankshaft, wherein the bearing members are divided into two in the direction of both side surfaces and are opposed to each other in a state of being assembled to a cylinder block At least in the actual use environment of the internal combustion engine between Using split elements having gaps at intervals where the end faces do not contact each other, wedges in the assembly direction with respect to the split elements together with the side surfaces forming the recesses on both side portions of the mating surface via the bearing surfaces. While providing the engaging part which has the engaging surface which provides an effect | action, on the mating surface with respect to the cylinder block of each said division | segmentation element, the said wedge with the side surface of each said division element which engages with the said engagement part and touches each said side surface An engagement portion having an engagement surface that receives an action is provided, and the respective division elements are fitted into the recesses by the wedge action, thereby positioning the bearing member with respect to the cylinder block.

  As effects of the present invention, the following effects can be obtained.

  In claim 1, the influence of the difference in thermal expansion between the cylinder block and the bearing member can be absorbed, and the step generated on the mating surface between the cylinder block and the bearing member can be obtained even during actual operation of the internal combustion engine. This can be eliminated, and the friction associated with the rotation of the crankshaft can be reduced.

  According to the second aspect, the bearing member can be reliably positioned with respect to the cylinder block. Further, the step generated on the mating surface between the cylinder block and the bearing member can be effectively eliminated, and an increase in friction due to the rotation of the crankshaft can be prevented.

  According to the third aspect of the present invention, it is possible to increase the support rigidity of the bearing member with respect to the crankshaft, and to improve the holding performance of the crank bearing (bearing metal) interposed between the bearing member and the crankshaft by the bearing member. it can.

According to the fourth aspect of the present invention, the influence of the difference in thermal expansion between the cylinder block and the bearing member can be absorbed, and the level difference generated at the mating surface between the cylinder block and the bearing member can be obtained even during actual operation of the internal combustion engine. This can be eliminated, and the friction associated with the rotation of the crankshaft can be reduced.
Further, the bearing member can be reliably positioned with respect to the cylinder block. Thus, when the bearing portion of the crankshaft is co-machined, and the bearing member is reassembled to the cylinder block along with the incorporation of the crankshaft, the roundness of the shaft hole by the co-machining is ensured.

Next, embodiments of the invention will be described.
The crankshaft support structure for an internal combustion engine according to the present invention is applied to a plurality of bulkheads (partitions) provided between cylinders of a cylinder block, such as a multi-cylinder internal combustion engine (multi-cylinder engine) for an automobile. It is used for an internal combustion engine having a configuration in which a crank cap is used as a bearing member to be assembled and a crankshaft is supported.

  1st Embodiment of this invention is described using FIGS. 1-3. FIG. 1 is a partial cross-sectional view showing a crankshaft support structure according to the first embodiment of the present invention, FIG. 2 is a partially enlarged view showing a modification of the engaging portion, and FIG. 3 is a first embodiment of the present invention. It is explanatory drawing which shows the crankshaft support method which concerns.

As shown in FIG. 1, the crankshaft support structure for an internal combustion engine according to this embodiment supports the crankshaft 1 together with a bearing surface 16 formed on the cylinder block 10 that is assembled to the cylinder block 10 constituting the internal combustion engine. A crank cap 20 as a bearing member is configured to contact the cylinder block 10 at a mating surface 13 of the cylinder block 10 with respect to the crank cap 20 and both side surfaces 14 and 14 that form the recess 12 together with the mating surface 13. .
In the following description, the vertical direction and the horizontal direction in FIG. 1 are defined as the vertical direction and the horizontal direction in the crankshaft support structure of the internal combustion engine according to the present embodiment. Therefore, although illustration is omitted, a cylinder head is assembled on the upper side of the cylinder block 10 constituting the internal combustion engine, and an oil pan is assembled on the lower side.

In the crankshaft support structure for the internal combustion engine according to the present embodiment, the crank cap 20 is composed of the two divided elements 21 and 22 divided in the direction of the side surfaces 14 and 14, and each divided element. In a state where 21 and 22 are assembled to the cylinder block 10, there is a gap 25 between the end faces 21a and 22a facing each other at a distance D1 at which the end faces 21a and 22a do not contact each other in at least the actual use environment of the internal combustion engine. It has a configuration.
In other words, the crank cap that has been integrated in each support portion (bearing portion) of the crankshaft with respect to the cylinder block of the crankshaft in the past has a left and right divided structure, and the divided crank cap is attached to the cylinder block with a predetermined interval. It becomes the composition assembled to it.
Hereinafter, among the divided elements 21 and 22 constituting the crank cap 20, the divided element 21 positioned on the left side is referred to as the left cap element 21, and the divided element 22 positioned on the right side is referred to as the right cap element 22.

  The recess 12 into which the crank cap 20 is fitted and assembled is formed below the bulkhead (partition wall) 11 provided between the cylinders in the cylinder block 10. That is, a plurality of bulkheads 11 (for example, five in the case of four cylinders) are provided so as to separate the cylinders in the cylinder block 10 in a direction perpendicular to the paper surface in FIG. Is formed.

The recess 12 protrudes to the left and right sides of the mating surface (hereinafter referred to as “block side mating surface”) 13 of the cylinder block 10 with respect to the crank cap 20 formed at the lower portion of the bulkhead 11 and the lower portion of the cylinder block 10. The side surfaces (hereinafter referred to as “block side surfaces”) 14 and 14 are the inner surfaces of the skirt portions 15 and 15 provided.
A bearing surface 16 that is semicircular when viewed in the axial direction of the crankshaft 1 (hereinafter simply referred to as “viewed in the crankshaft direction”) is provided at the left and right central portions of the lower portion of the bulkhead 11, that is, the left and right central portions of the block side mating surface 13. Is formed.

As described above, the crank cap 20 having the divided structure of the left cap element 21 and the right cap element 22 has a substantially central position in the left-right direction in the present embodiment.
Therefore, the left cap element 21 and the right cap element 22 are substantially symmetrical in the state of being assembled to the cylinder block 10, and the crank cap 20 is opposed to the bearing surface 16 on the cylinder block 10 side. A bearing surface 26 that is semicircular when viewed from the crankshaft direction is formed on the side. That is, the left cap element 21 and the right cap element 22 have bearing surface portions 26a and 26b that form the bearing surface 26 in a state of being assembled to the cylinder block 10 and are arcuate when viewed in the crankshaft direction.

The left cap element 21 and the right cap element 22 are in contact with the block-side mating surface 13 and the block-side side surface 14 while being fitted in the recess 12 of the cylinder block 10. That is, each cap element 21, 22 has a mating surface (hereinafter referred to as “cap-side mating surface”) 23 of the crank cap 20 with respect to the cylinder block 10, and a side surface (hereinafter referred to as “cap-side side surface”) in contact with the block-side side surface 14. And 24).
That is, the left cap element 21 and the right cap element 22 are fitted in the recess 12 and assembled to the cylinder block 10, and the block side mating surface 13 and the cap side mating surface 23 are in contact with each other, and the block side surface 14. And the cap side surface 24 are in contact with each other.

In such a configuration, the left cap element 21 and the right cap element 22 are fitted into the recess 12 of the cylinder block 10 and assembled, whereby the bearing surface 16 on the cylinder block 10 side and the bearing surface 26 on the crank cap 20 side are Thus, a shaft hole (bearing portion) is formed. The crankshaft 1 (specifically, the crank journal 1a) is supported in the shaft hole via the upper bearing 18 and the lower bearing 29 each having a semicircular shape and along the bearing surfaces 16 and 26. The crankshaft 1 is supported. Oil (lubricating oil) is interposed between the upper bearing 18 and the lower bearing 28 and the crankshaft 1 (see oil 5 in FIG. 3).
The left cap element 21 and the right cap element 22 are individually fastened and fixed to the cylinder block 10 by stud bolts 27 penetrating the cap elements 21 and 22 in the vertical direction while being fitted in the recess 12. . That is, the stud bolt 27 is inserted into the cap elements 21 and 22 from below and is screwed into the block-side mating surface 13 so that the cap elements 21 and 22 are fastened and fixed to the cylinder block 10. To do.

  Further, a gap 25 is provided between the opposed end surfaces 21 a and 22 a between the left cap element 21 and the right cap element 22 in a state assembled to the cylinder block 10. As described above, the size of the gap D1 of the gap 25 is set so that the end faces 21a and 22a do not contact each other at least under the actual use environment of the internal combustion engine.

That is, for the internal combustion engine configured using the cylinder block 10 according to the present embodiment, the left cap element 21 and the right cap element in an actual usage environment including actual operation and when the temperature of each part rises. The end faces 21a and 22a of the cap elements 21 and 22 are not in contact with each other due to thermal expansion of each of the 22 and deformation due to a difference in thermal expansion between the cylinder block 10 and the crank cap 20, so The size of the gap D1 of the gap 25 is ensured. In other words, the gap 25 allows expansion and contraction of the distance D1 between the end surfaces 21a and 22a due to deformation of the cylinder block 10 and the crank cap 20 due to temperature changes in an actual use environment of the internal combustion engine. The size of the gap D1 of the gap 25 is set to, for example, about 5 mm.
Note that “in the actual use environment of the internal combustion engine” here is not an operating state of the internal combustion engine under a special environment such as when driving a car in a dusty place or the seaside, for example, and is normally used normally. It means that the internal combustion engine is in an operating state (load, rotational speed, temperature, etc.) that can be performed (in a range that is normally used). However, the size of the gap D1 of the gap 25 can be appropriately set according to the use environment of the internal combustion engine. In addition, the gap 25 in FIG. 1 and the like is actually very small in comparison with the length in the left-right direction of each cap element 21 and 22, but is exaggerated for convenience of explanation.

Further, in the crank cap 20 that supports the crankshaft 1, it is preferable that the gap D <b> 1 of the gap 25 is set to a minimum necessary size from the viewpoint of securing the support function. If the gap D1 of the gap 25 is larger than necessary, a phenomenon such as the lower bearing 28 bulging and deforming toward the gap 25 due to thermal deformation or the like during actual operation of the internal combustion engine occurs, and the crank shaft 1 is supported by the crank cap 20. May not be secured.
Accordingly, the size of the gap D1 of the gap 25 is within a range where the support function of the crankshaft 1 by the crank cap 20 can be secured without allowing the lower bearing 28 to bulge and deform under the actual use environment of the internal combustion engine. Set by.

As a specific example of the size of the gap D1 of the gap 25, the cylinder block 10 is made of aluminum having a thermal expansion coefficient α = 23.9 × 10 ⁻⁶ / K in a temperature range of −30 to 150 ° C. However, when the left and right cap elements 21 and 22 are made of cast iron having a thermal expansion coefficient α = 10.5 × 10 ⁻⁶ / K under the same temperature range, the gap D1 of the gap 25 is , 0.38 mm.

  Thus, the crank cap 20 has a left and right divided structure of the left cap element 21 and the right cap element 22, and the left and right cap elements 21 and 22 are cylinders with a gap having a predetermined interval as described above. By being assembled to the block 10, the influence of the thermal expansion difference between the cylinder block 10 and the crank cap 20 can be absorbed, and the cylinder block 10 and the crank cap can be used even during actual operation of the internal combustion engine. 20 can be eliminated, and the friction caused by the rotation of the crankshaft 1 can be reduced.

Further, by making the crank cap 20 into a left and right divided structure, a downward load from the crankshaft 1 is applied to the cylinder block via the cap side surface 24 and the block side surface 14 for the left cap element 21 and the right cap element 22, respectively. Can be received on the 10th side.
That is, in the configuration in which the crank cap is integrated as in the prior art, the load from the crankshaft 1 can be received only by the crank cap, but the crank cap 20 has a left and right divided structure as described above. The load from the crankshaft 1 can also be received on the cylinder block 10 side. Thereby, the load burden from the crankshaft 1 of the crankcap 20 can be reduced.

In the crankshaft support structure for an internal combustion engine according to the present embodiment, the following configuration is provided for positioning the crankcap 20 with respect to the cylinder block 10.
That is, on the cylinder block 10 side, each of the block-side side surfaces 14 of the block-side mating surface 13 via the bearing surface 16 and the block-side side surfaces 14 that form the recesses 12, respectively, with respect to the left cap element 21 and the right cap element 22. An engagement portion 30 having an engagement surface 31 that provides a wedge action in the assembly direction is provided.
On the other hand, on the crank cap 20 side, the wedges together with the cap side mating surfaces 23 of the left cap element 21 and the right cap element 22 together with the cap side surfaces 24 that engage with the engaging portions 30 and contact the block side surfaces 14. An engagement portion 40 having an engagement surface 41 that receives the action is provided.

As shown in FIG. 1, an engagement portion (hereinafter referred to as “block-side engagement portion”) 30 provided on the cylinder block 10 side has a V-shaped cross section when viewed from the crankshaft direction in this embodiment. It is formed as a V notch, and is provided at a substantially central portion in each of a left side portion and a right side portion sandwiching the bearing surface 16 of the block side mating surface 13. The block-side engaging portion 30 is formed so as to be a concave portion having a V-shaped cross-section with respect to the block-side mating surface 13, so that when viewed in the direction of the crankshaft in the direction shown in FIG. Type).
In addition, regarding the shape of the block side engaging portion 30, as a shape whose cross-sectional shape is V-shaped when viewed in the crankshaft direction, for example, a V-shaped groove extending in the crankshaft direction, or a conical shape or a pyramid shape. A recess or the like is conceivable.

The block-side engagement portion 30 is an engagement surface (hereinafter referred to as a “block-side engagement surface”) 31 that gives a wedge action in the assembly direction to the left and right cap elements 21 and 22 together with the block-side side surface 14. Have
In this embodiment, the block-side engagement surface 31 is an inner slope (slope on the crankshaft 1 side) in the block-side engagement portion 30 having a V-shaped cross section when viewed in the crankshaft direction.

On the other hand, an engagement portion (hereinafter referred to as a “cap side engagement portion”) 40 provided on the crank cap 20 side is formed in a shape that can be fitted in accordance with the shape of the block side engagement portion 30, and left On the cap side mating surface 23 of each of the cap element 21 and the right cap element 22, each cap element 21, 22 is provided at a position corresponding to the block side engaging portion 30 in a state where it is assembled to the cylinder block 10. In the present embodiment, the cap-side engagement portion 40 has a V-shaped cross-section with respect to the cap-side mating surface 23 corresponding to the block-side engagement portion 30 having a V-shaped cross-section when viewed in the crankshaft direction. 1 is formed in an inverted V shape (mountain shape) when viewed in the direction of the crankshaft in the direction shown in FIG.
Therefore, when the shape of the block-side engagement portion 30 is a V-shaped groove, the cap-side engagement portion 40 is formed into a triangular protrusion with a cross-sectional shape that can be fitted in accordance with the shape. When the shape of the engaging portion 30 is a conical or pyramidal concave portion, it is formed into a conical or pyramidal convex portion that can be fitted accordingly.

The cap side engaging portion 40 has an engaging surface (hereinafter referred to as “cap side engaging surface”) 41 that engages with the block side engaging portion 30 and receives a wedge action together with the cap side surface 24.
In this embodiment, the cap-side engagement surface 41 is a surface in contact with the block-side engagement surface 31 in a state where the cap-side engagement portion 40 is fitted to the block-side engagement portion 30, as viewed in the crankshaft direction. It becomes an inner slope (slope on the crankshaft 1 side) in the cap-side engaging portion 40 having a letter shape.

The block-side engaging portion 30 and the cap-side engaging portion 40 configured as described above provide a wedge action for each of the left cap element 21 and the right cap element 22 when the crank cap 20 is assembled to the cylinder block 10.
That is, the block-side engagement surface 31 and the block-side side surface 14 become wedge surfaces that give a wedge action to the cap elements 21 and 22, and the cap-side engagement surface 41 and the cap-side side surface 24 in each cap element 21 and 22. However, it becomes a wedge surface which receives a wedge action from the cylinder block 10 side. Therefore, when the left cap element 21 and the right cap element 22 are assembled, the cap side engaging surface 41 slides with respect to the block side engaging surface 31, and the cap side side 24 slides with respect to the block side side surface 14, respectively. The cap elements 21 and 22 are fitted into the concave portion 12 of the cylinder block 10 with a wedge action via the cap side engaging surface 41 and the cap side side surface 24.
That is, when the crank cap 20 is fitted to the cylinder block 10, the cap-side engagement surface 41 slides with respect to the block-side engagement surface 31, so that the cap elements 21 and 22 are moved in the left-right direction. As the cap side surface 24 slides with respect to the block side surface 14 while being moved outward, a wedge action is obtained in which movement of the cap elements 21 and 22 outward in the left-right direction is restricted. Thereby, it is possible to position the cap elements 21 and 22 in the left-right direction.

Further, in the present embodiment, the block-side engagement surface 31 serving as the wedge surface and the cap-side engagement surface 41 corresponding thereto, and the block-side side surface 14 and the cap-side side surface 24 corresponding thereto are provided with respect to the cylinder block 10 of the crank cap 20. With respect to the assembly direction (upward direction in FIG. 1), both engagement surfaces 31 and 41 are inclined surfaces, and both side surfaces 14 and 24 are substantially parallel surfaces. -24 should just be a slope which at least any one can obtain the wedge action mentioned above. In other words, the engaging surfaces 31 and 41 and the side surfaces 14 and 24 are narrowed in the assembling direction side so that a wedge action can be obtained for the cap elements 21 and 22 when the crank cap 20 is assembled. As long as they are flat surfaces.
Accordingly, the both engaging surfaces 31 and 41 are substantially parallel surfaces and the both side surfaces 14 and 24 are inclined surfaces, or both the engaging surfaces 31 and 41 and both side surfaces 14 and 24 are both inclined surfaces. There may be. However, as described above, from the viewpoint of receiving the load from the crankshaft 1 through the cap side surface 24 and the block side surface 14, the both side surfaces 14, 24 are in the assembling direction. It is considered that the surface is preferably substantially parallel to the surface.

Moreover, about the block side engaging part 30 and the cap side engaging part 40, the block side engaging part 30 may be comprised as a convex part, and the cap side engaging part 40 may be comprised as a recessed part. An example of the configuration will be described with reference to FIG.
That is, as shown in FIG. 2, the cap-side engaging portion 40 is formed as a V-notch that is V-shaped when viewed in the crankshaft direction, and the block-side engaging portion 30 has the shape of the cap-side engaging portion 40. The cross-sectional shape is formed into a V-shaped convex portion as viewed in the crankshaft direction so that the fitting is possible.
Then, in the block side engaging portion 30 having a V-shaped cross section when viewed in the crankshaft direction, the outer slope (the slope opposite to the crankshaft 1 side) becomes the block side engaging surface 31, In the cap-side engagement portion 40 that is a V-shaped recess when viewed in the axial direction, the outer slope (the slope opposite to the crankshaft 1 side) serves as the cap-side engagement surface 41.

As described above, the engaging portions are provided on the cylinder block 10 side and the crank cap 20 side, respectively, and when the crank cap 20 is assembled to the cylinder block 10, each of the left cap element 21 and the right cap element 22 is recessed with the wedge action. By being configured to be fitted into the crankshaft, the crank cap 20 can be reliably positioned with respect to the cylinder block 10.
That is, as will be described later, when the crank cap 20 is assembled to the cylinder block 10, after the shaft hole is co-processed in a state where the crank cap 20 is assembled to the cylinder block 10, the crank cap 20 is once removed. As a result, when the crankshaft 1 is reassembled together with the crankshaft 1, the position of the crankcap 20 relative to the cylinder block 10 is uniquely determined when the crankcap 20 is initially assembled and reassembled.

Thereby, the level | step difference in the mating surface of the cylinder block 10 and the crank cap 20 at the time of reassembly of the crank cap 20 becomes a level at the time of co-processing, and the roundness of the shaft hole by co-processing is ensured.
Further, since the crank cap 20 has a divided structure of the left cap element 21 and the right cap element 22, the cylinder block 10 and the crank on the mating surface can be used even in an environment where the temperature changes, such as during actual operation of the internal combustion engine. The relative bonding position relationship with the cap 20 does not change, and the step does not increase (occur). That is, the step generated on the mating surface between the cylinder block 10 and the crank cap 20 can be effectively eliminated, and the increase of friction due to the rotation of the crankshaft 1 can be prevented.

Next, a crankshaft support method for an internal combustion engine according to the present embodiment will be described with reference to FIG.
In the crankshaft support method for an internal combustion engine according to the present embodiment, the crankcap 20 is assembled to the cylinder block 10 without incorporating the crankshaft 1 and co-working is performed on the bearing portion of the crankshaft 1. The crank cap 20 is once removed from the cylinder block 10, and the crank cap 20 is assembled again to the cylinder block 10 with the crankshaft 1 being assembled.
Then, the left cap element 21 and the right cap element 22 are fitted into the recess 12 of the cylinder block 10 with a wedge action obtained by the block side engaging portion 30 and the cap side engaging portion 40, etc. The cylinder block 10 is positioned.

Specifically, first, from the state before assembling the crank cap 20 shown in FIG. 3A, initial assembly for assembling the crank cap 20 to the cylinder block 10 without assembling the crank shaft 1 is performed.
That is, the left cap element 21 and the right cap element 22 are fitted into the recess 12 of the cylinder block 10 so that the cap side engaging portion 40 is aligned with the block side engaging portion 30. At this time, the cap-side engagement surface 41 slides with respect to the block-side engagement surface 31 and the cap-side side surface 24 slides with respect to the block-side side surface 14 to obtain a wedge action.

Then, as shown in FIG. 3B, the crank cap 20 fitted in the recess 12 is fastened and fixed to the cylinder block 10 by the stud bolt 27. By fastening with the stud bolt 27, the cap side engaging portion 40 bites into the block side engaging portion 30, and the left cap element 21 and the right cap element 22 are joined to the cylinder block 10 while obtaining a wedge action. Thus, the initial assembly of the crank cap 20 to the cylinder block 10 is completed with the gap 25 between the left cap element 21 and the right cap element 22.
Thus, by obtaining a wedge action when assembling the crank cap 20, it is possible to achieve the assembling without the backlash (gap) of the crank cap 20 with respect to the cylinder block 10.

Subsequently, after the initial assembly is completed, the shaft hole (bearing portion) formed by the bearing surface 16 on the cylinder block 10 side and the bearing surface 26 (26a, 26b) on the crank cap 20 side (see FIG. 3A). On the other hand, co-processing is performed by applying processing such as honing.
As a result, as shown in FIG. 3B, when the crank cap 20 is initially assembled, the step 50 on the mating surface between the cylinder block 10 and the crank cap 20 is removed, and a predetermined roundness is obtained for the shaft hole. (See FIG. 3C).

From the state after the end of the co-processing shown in FIG. 3C, the fastening by the stud bolt 27 is released, and the left cap element 21 and the right cap element 22 are once removed from the cylinder block 10.
Then, as shown in FIG. 3D, reassembly is performed by reassembling the crank cap 20 to the cylinder block 10 with the crankshaft 1 being assembled. That is, by assembling the crank cap 20 to the cylinder block 10, the crankshaft 1 (crank journal) is supported between the cylinder block 10 and the crank cap 20 via the upper bearing 18 and the lower bearing 28. The oil 5 is interposed between the upper bearing 18 and the lower bearing 28 and the crankshaft 1.

  When the crank cap 20 is reassembled, a wedge action is obtained in the same manner as in the initial assembly, so that the crank cap 20 can be assembled without backlash to the cylinder block 10. Thus, when the crank cap 20 is reassembled, the initial assembly state of the assembly position of the cylinder block 10 is reproduced.

FIG. 3E shows the state of the support portion of the crankshaft 1 during actual operation of the internal combustion engine. As shown in FIG. 3 (e), even if each part becomes a high temperature state due to the operation of the internal combustion engine from the reassembly completion state shown in FIG. No step due to misalignment occurs on the mating surface with the crank cap 20.
That is, since the crank cap 20 is firmly joined to the cylinder block 10 by the wedge action by the block side engaging portion 30 and the cap side engaging portion 40 and the stud bolt 27, the mating surface is prevented from shifting. The Further, due to the gap 25 interposed between the left cap element 21 and the right cap element 22 in the crank cap 20, the expansion of the crank cap 20 due to the thermal expansion of each part of the cylinder block 10 and the crank cap 20 and the difference between these thermal expansions. And shrinkage is absorbed. For these reasons, even when the cylinder block 10 and the crank cap 20 are in a high temperature state, it is possible to prevent a step from occurring on the mating surface of the cylinder block 10 and the crank cap 20.

  A second embodiment of the present invention will be described with reference to FIGS. 4 and 5. 4 is a partial cross-sectional view showing a crankshaft support structure according to a second embodiment of the present invention, and FIG. 5 is a view taken in the direction of arrow A in FIG. In addition, about the content which overlaps with 1st embodiment, the description is abbreviate | omitted suitably using the same code | symbol.

  As shown in FIGS. 4 and 5, the crank cap 60 according to the present embodiment has a divided structure having a left cap element 61 and a right cap element 62, and a portion of the crank cap 60 that forms the bearing surface 66 thereof. At least a part is provided with an overlapping portion 69 in which the left and right cap elements 61 and 62 overlap each other in the axial direction of the crankshaft 1.

  The left cap element 61 and the right cap element 62 are substantially symmetrical in the state of being assembled to the cylinder block 10, and are disposed on the crank cap 60 side so as to face the bearing surface 16 on the cylinder block 10 side. A bearing surface 66 that is semicircular when viewed from the crankshaft direction is formed. That is, each of the left cap element 61 and the right cap element 62 has the bearing surface portions 66a and 66b that form the bearing surface 66 in a state of being assembled to the cylinder block 10 and have an arc shape when viewed in the crankshaft direction.

The overlapping portion 69 provided in the crank cap 60 is constituted by overlapping protrusions 61c and 62c formed on the left cap element 61 and the right cap element 62, respectively.
The overlapping protrusions 61c and 62c protrude to the opposite sides of the left cap element 61 and the right cap element 62, and the overall thickness of the crank cap 60 (the direction of the crankshaft) is the thickness of each cap element 61 and 62. Is formed as a thin plate portion having a thickness that is substantially half of the length of the length. That is, the overlapping protrusions 61c and 62c are overlapped with each other in the axial direction of the crankshaft 1 when the cap elements 61 and 62 are assembled to the cylinder block 10, and the thickness of the crank cap 60 is equalized as a whole in the overlapped state. The overlapping portion 69 is formed in the crank cap 60. In the present embodiment, with respect to the overlapping protrusions 61c and 62c, the overlapping protrusion 61c of the left cap element 61 is on the rear side in the axial direction of the crankshaft 1, as viewed in the crankshaft direction shown in FIG. Similarly, 62c is configured to be on the near side.

In the overlapping portion 69 of the crank cap 60, a part of the bearing surface 66 is constituted by both bearing surface portions 66 a and 66 b of the left and right cap elements 61 and 62.
That is, the bearing surface portion 66a of the left cap element 61 includes the overlapping protrusion 61c and extends to the right side of the center position of the crankshaft 1 in the left-right direction, and the bearing surface portion 66b of the right cap element 62 has the overlapping protrusion 62c. In addition, it extends to the left side of the center position of the crankshaft 1 in the left-right direction. Thereby, the part corresponding to the overlap part 69 of the bearing surface 66 is comprised by both the bearing surface parts 66a and 66b.

  The crank cap 60 has the left cap element 61 and the right cap element 62 assembled to the cylinder block 10 so that the end faces do not contact each other at least under the actual use environment of the internal combustion engine. There are gaps 65a and 65b with a distance D2.

As shown in FIG. 5, in the cap elements 61 and 62 of the crank cap 60 according to the present embodiment, the end surfaces facing each other are the outer end surfaces 61 a and 62 a that are the surfaces from which the overlapping protrusions 61 c and 62 c protrude, and the overlapping It will have inner end surface 61b * 62b used as the front end surface of protrusion 61c * 62c.
Accordingly, a gap 65a is provided between the outer end surface 61a of the left cap element 61 and the inner end surface 62b of the right cap element 62, and between the inner end surface 61b of the left cap element 61 and the outer end surface 62a of the right cap element 62. A gap 65b is provided. The distance D2 between the gaps 65a and 65b is set in substantially the same manner as the distance D1 between the gaps 25 in the crank cap 20 of the first embodiment.

  The shapes of the cap elements 61 and 62 in the overlapping portion 69 of the crank cap 60, that is, the shapes of the overlapping protrusions 61c and 62c are not limited to this embodiment. For example, each of the overlapping protrusions 61c and 62c may have a shape such that the opposed outer end surfaces 61a and 62a and inner end surfaces 61b and 62b are curved surfaces.

As described above, by providing the overlapping portion 69 in at least a part of the crank cap 60 where the bearing surface 66 is formed, the support rigidity of the crank cap 60 with respect to the crankshaft 1 can be increased, and The retainability of the lower bearing 28 can be improved.
That is, in the overlapping portion 69 of the crank cap 60, the crankshaft 1 is supported by the bearing surface portions 66a and 66b of the left and right cap elements 61 and 62 constituting the bearing surface 66, so that the crankshaft 1 is supported via the bearing surface portions 66a and 66b. Support rigidity from both the left cap element 61 and the right cap element is obtained, and the support rigidity of the crank cap 60 with respect to the crankshaft 1 can be increased. Further, by providing the overlapping portion 69 of the crank cap 60, the portion where the lower bearing 28 does not contact the bearing surface 66 can be eliminated, and the retainability of the lower bearing 28 by the crank cap 60 can be improved.

The partial cross section figure which shows the crankshaft support structure which concerns on 1st embodiment of this invention. The partially expanded view which shows the modification of an engaging part. Explanatory drawing which shows the crankshaft support method which concerns on 1st embodiment of this invention. The partial cross section figure which shows the crankshaft support structure which concerns on 2nd embodiment of this invention. FIG. The partial cross section figure which shows the conventional crankshaft support structure. Explanatory drawing which shows the level | step difference of the mating surface in the conventional crankshaft support structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crankshaft 10 Cylinder block 12 Recess 13 Block side mating surface 14 Block side side 16 Bearing surface 20 Crank cap (bearing member)
21 Left cap element (split element)
21a End face 22 Right cap element (dividing element)
22a end face 23 cap side mating face 24 cap side face 25 gap 30 block side engaging part 31 block side engaging face 40 cap side engaging part 41 cap side engaging face 60 crank cap 61 left cap element 61a outer end face 61b inner end face 62 Right cap element 62a Outer end face 62b Inner end face 66 Bearing surface 69 Overlapping part

Claims (4)

Both side surfaces of the bearing member that is assembled to the cylinder block and that supports the crankshaft together with the bearing surface formed on the cylinder block form a mating surface of the cylinder block with respect to the bearing member and a recess with the mating surface. A crankshaft support structure for an internal combustion engine configured to contact at
The bearing member is composed of two divided elements divided in the direction of the both sides, and at least between the end faces facing each other in a state where each divided element is assembled to the cylinder block. A crankshaft support structure for an internal combustion engine, characterized by having a gap having an interval at which the end faces do not contact each other in an actual use environment. An engaging portion having an engaging surface that applies a wedge action in the assembling direction to each of the split elements together with each of the side surfaces forming the concave portion on each side portion of the cylinder block mating surface through the bearing surface. While providing
An engagement portion having an engagement surface that receives the wedge action together with a side surface of each division element that engages with the engagement portion and contacts each side surface is provided on a mating surface of each division element with respect to the cylinder block. The crankshaft support structure for an internal combustion engine according to claim 1.   The overlapping portion in which the split elements overlap with each other in the axial direction of the crankshaft is provided in at least a part of a portion forming the bearing surface of the bearing member. Crankshaft support structure for an internal combustion engine. Using a bearing member that is assembled to the cylinder block and supports the crankshaft together with the bearing surface of the cylinder block, and is in contact with the cylinder block on the mating surface of the cylinder block with respect to the bearing member and on both side surfaces that form a recess with the mating surface ,
After the bearing member is assembled to the cylinder block without incorporating the crankshaft, the bearing portion of the crankshaft is co-processed, and then the bearing member is temporarily removed from the cylinder block, and the bearing member is assembled to the crankshaft. A crankshaft support method for an internal combustion engine to be reassembled to a cylinder block,
The bearing member is divided into two in the direction of the both side surfaces, and a gap having a gap between the end faces that are opposed to each other in an assembled state with the cylinder block at least in the actual use environment of the internal combustion engine. Using elements,
While providing each side part via the bearing surface in the mating surface with an engaging portion having an engaging surface that gives a wedge action in the assembly direction to each of the split elements together with each side surface forming the recess, An engagement portion having an engagement surface that receives the wedge action together with a side surface of each division element that engages with the engagement portion and contacts each side surface is provided on a mating surface of each division element with respect to the cylinder block;
A method for supporting a crankshaft of an internal combustion engine, comprising: positioning each of the bearing members with respect to a cylinder block by fitting each of the divided elements into the recess with the wedge action.

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