JP2006348859A - Cylinder block for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder block for an internal combustion engine easy to manufacture and machine and effectively less in vibration. <P>SOLUTION: The cylinder block 12 for the internal combustion engine 10 comprises a cylinder 24 and a crank case 26 having bearing portions 20 for supporting crank shafts 18. The bearing portions 20 are each formed with an independent crank cap 32. An reinforcing member 38 has a first portion 38a fixed along the lower edge of the crank cap 32 and a second portion 38b extending from the first portion 38a adjacent thereto and having an intermediate part 38bc fixed to the crank case 26. This construction suppresses vibration with the crank case 26 having a lower part constrained by the second portion 38b of the reinforcing member 38. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cylinder block of an internal combustion engine, and more particularly to a technique for suppressing vibration of a bottom rail portion of the cylinder block.

  A cylinder block in an internal combustion engine such as a gasoline engine or a diesel engine is composed of a cylinder in which a piston is slidably disposed, and a crankcase that is positioned below the cylinder and accommodates a crankshaft. The crankcase is provided with a bearing portion that rotatably supports the crankshaft. In the case of a multi-cylinder internal combustion engine, the bearing portion is configured by connecting a crank cap (also referred to as a bearing cap) to each of an end wall of the crankcase and a partition wall in the crankcase.

  Since such a cylinder block receives force at different timings from periodically changing gas pressure and moving parts (piston, connecting rod, crank arm, etc.), vibration is likely to occur in the crankcase.

  For such a problem, it is conceivable to increase the rigidity of the crankcase by increasing the thickness of the crankcase, but this is contrary to the demand for weight reduction of the internal combustion engine. For this reason, conventionally, as described in, for example, Patent Document 1 and Patent Document 2 below, the crankcase is composed of two upper and lower bodies, and a crank cap is integrally formed with the lower crankcase to increase rigidity. A so-called bed plate structure is considered.

  In addition, as described in Patent Document 3, a vertical beam is integrated at each of the left and right ends of the crank cap, and a horizontal beam is provided at the lower edge of the crank cap, thereby reducing the stress of the crank cap and falling down. A configuration is known in which the rigidity of the cylinder is improved and the vibration of the cylinder block is suppressed.

Alternatively, as shown in FIG. 6, which is a schematic bottom view showing a part of the cylinder block, the lateral beam 1 is extended from the end of the crank cap 2 to the protrusion 4 provided on the inner wall of the crankcase 3. The structure fixed with the volt | bolt 5 is also known.
Japanese Patent Laid-Open No. 7-119545 Japanese Patent Laid-Open No. 8-200234 JP-A-8-284749

  However, when a cylinder block having a bed plate structure as disclosed in Patent Documents 1 and 2 is manufactured by general casting, it is difficult to manufacture and process and the cost is high due to accuracy. There is a problem.

  In addition, the structure reinforced with the transverse beam or the longitudinal beam is easy to manufacture and process, but there is a problem that vibration is not sufficiently suppressed at the lower part of the crankcase, that is, a so-called skirt part.

  Accordingly, an object of the present invention is to provide a cylinder block of an internal combustion engine that is easy to manufacture and process and can effectively suppress vibration.

  In order to achieve the above object, a cylinder block of an internal combustion engine according to the present invention is not of a bed plate structure, that is, includes a cylinder and a crankcase having a bearing portion for supporting a crankshaft, each of the bearing portions being A first part that is constituted by an individual crank cap and is fixed along the free edge of the crank cap, and a second part that extends between adjacent first parts and whose intermediate part is fixed to the crankcase It is characterized by providing the reinforcing member which has.

  According to the said structure, the lower part of a crankcase is restrained by the 2nd part of a reinforcement member. In particular, the lower portion of the crankcase located in the region between the adjacent bearing portions is likely to vibrate, but is restrained by the second portion of the reinforcing member, so that vibration is suppressed.

  In addition, the second part of the reinforcing member has a mountain shape composed of a hypotenuse extending obliquely from one of the adjacent first parts and a hypotenuse extending obliquely from the other first part, and the apex at which the hypotenuses intersect. It is preferable to fix the portion to the crankcase. Since the second portion has an oblique portion with respect to the first portion, the strength in the oblique direction is improved, and deformation and twisting of the parallelogram on the lower surface of the cylinder block can be suppressed.

  As described above, the cylinder block of the internal combustion engine according to the present invention is not a structure in which the crank cap is integrated as in the bed plate structure, and is a structure in which only a relatively simple reinforcing member is fixed. Manufacturing and processing are easy and cost increase can be prevented.

  Further, since the portion of the crankcase that is prone to vibration can be constrained, vibration is suppressed, and as a result, noise can be reduced.

  Hereinafter, preferred embodiments of a cylinder block of an internal combustion engine according to the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  FIG. 1 is a longitudinal sectional view schematically showing a four-cylinder gasoline engine 10 as an internal combustion engine to which a cylinder block according to the present invention is applied. As shown in the figure, the engine 10 basically includes a cylinder block 12, a cylinder head 14 fixed to the upper part of the cylinder block 12, and an oil pan 16 fixed to the lower part of the cylinder block 12. . A crankshaft 18 is accommodated in the cylinder block 12 and is rotatably supported by a bearing portion 20 of the cylinder block 12.

  In the cylinder block 12 according to the illustrated embodiment, cylinders 24 on which pistons 22 are slidably arranged are arranged in series, and a crankcase 26 is integrally provided at a lower portion thereof. A bearing portion 20 that supports the crankshaft 18 is formed in the crankcase 26.

  The inside of the crankcase 26 is partitioned by partitions 28 into the same number of spaces as the number of cylinders, and each space communicates with the inside of the corresponding cylinder 24. In this space, the crank arm 18a, the crank pin 18b, the connecting rod 30 and the like of the crankshaft 18 are arranged. Further, as shown in FIG. 2 which is a sectional view taken along line II-II in FIG. 1 showing only the cylinder block 12, a single plate-like crank cap 32 is provided by bolts 34 at the lower part of each partition wall 28. It is fixed individually. A semicircular recess is formed in the center of the lower edge of the partition wall 28 and the center of the upper edge of the crank cap 32, and the circular hole supports the crankshaft 18 by connecting the partition wall 28 and the crank cap 32. It is formed as a bearing portion 20. In addition, the bearing portion 20 is similarly formed by the crank cap 32 in the end walls 36 a and 36 b at both ends of the crankcase 26.

  Furthermore, the cylinder block 12 according to the illustrated embodiment includes a reinforcing member 38 for reinforcing the lower portion of the crankcase 26 and increasing the rigidity. The reinforcing member 38 is preferably made of a material that is easy to process and has high rigidity, for example, steel. As shown in FIG. 2 and FIG. 3 that is a bottom view of the cylinder block 12, each of the crank caps 32 is free. It is an integrated object composed of a first portion 38a disposed along an edge (lower edge) and a second portion 38b that connects the same ends of a pair of adjacent first portions 38a.

  The first portion 38a of the reinforcing member 38 is fastened together with a bolt 34 for fixing the crank cap 32 to the partition wall 28 or the end walls 36a, 36b of the crankcase 26.

  The second portion 38b of the reinforcing member 38 has a mountain shape including an oblique side portion 38ba extending obliquely from one of a pair of adjacent first portions 38a and an oblique side portion 38bb extending obliquely from the other first portion 38a. The apex portion 38bc, that is, the intermediate portion of the second portion 38b where both the oblique side portions 38ba and 38bb are tolerated is fixed to the lower edge of the crankcase 26 by the bolt 40. In this embodiment, since the oil pan 16 is attached to an outward flange (so-called bottom rail) 42 provided at the lower edge of the crankcase 26, it is integrally formed on the inner peripheral surface of the crankcase 26 so as not to obstruct it. The apex portion 38 bc of the second portion 38 b is fixed to the protruding portion 44 with a bolt 40.

  While the gasoline engine 10 is being driven, forces from moving parts such as the piston 22 and the crankshaft 18 propagate in various directions, and the gas pressure from the cylinder 24 acts in the crankcase 26 of the cylinder block 12. In such a configuration, the rigidity in the direction along the lower edge of the crank cap 32 (the direction indicated by the arrow A in FIGS. 2 and 3) is improved by the first portion 38a of the reinforcing member 38, whereby the crank in this direction is improved. Propagation of vibration through the cap 32 can be suppressed.

  Further, the second portion 38 b of the reinforcing member 38 restrains the movement of the lower part of the crankcase 26. This restraining portion is located between the bearing portion 20 (partition wall 28) and the bearing portion 20 (partition wall 28 or the end walls 36a, 36b), and is a portion where no restraining means has been provided conventionally. Therefore, the vibration of the restraint portion, in particular, the left-right opening movement (movement in the direction of arrow A in FIGS. 2 and 3) is effectively suppressed by the second portion 38b. As a result, vibration of the entire cylinder block 12 is suppressed and prevented, and problems such as noise are also improved.

  Further, the distance between the fixing point of the first portion 38a of the reinforcing member 38 (the position of the bolt 34) and the fixing point of the second portion 38b (the position of the bolt 40) is relative to the rotation axis of the crankshaft 18 and the direction of the arrow A. The structure in the oblique direction is also strengthened. In particular, in the present embodiment, since there is a hypotenuse portion of the second portion 38b between the fixed points 34 and 40, the structure is stronger. Thereby, it is possible to prevent the lower surface of the cylinder block 12 from being deformed into a parallelogram, and to improve the torsional rigidity of the cylinder block 12.

  In addition, although a trough part is formed between the adjacent 2nd part 38b, it is possible to form the lubricating oil channel | path 46 in this part. For example, in the conventional configuration shown in FIG. 6, since the lateral beam 1 is disposed in this portion, the lubricating oil passage 46 is provided on the outer surface of the crankcase 26. By using it, the outside dimension of the cylinder block 12 can be reduced. Further, since the lubricating oil passage 46 extends to the lower edge of the crankcase 26, the rigidity of the lower portion of the crankcase 26 is improved, and the vibration suppressing effect is further improved.

  Further, as understood from comparison between FIG. 3 and FIG. 6, there is an effect that the number of bolts for fixing the reinforcing member 38 can be reduced.

  As mentioned above, although preferred embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to the said embodiment.

  For example, since the strength of the center portion of the crank cap 32 is originally made high, the intermediate portion of the first portion 38a is omitted as shown in FIG. Can be expected.

  Further, in order to suppress the vibration of the lower portion of the crankcase 26 located in the region between the adjacent bearing portions 20, the shape of the second portion of the reinforcing member does not need to be a chevron, as shown in FIG. Various shapes such as a reinforcing member 38B in which the second portion 38b is T-shaped are conceivable. In addition, the reinforcing member 38B shown in FIG. 5 extends both ends of the first portion 38a, and this portion is fixed to the protrusion 48 provided on the inner wall of the crankcase 26 with the bolt 50, so that the cylinder block 12 is further improved. Increased rigidity.

  Furthermore, the applied internal combustion engine is not limited to a gasoline engine, but may be a diesel engine, and the number of cylinders and the arrangement type of the cylinders are not limited to those described above.

1 is a longitudinal sectional view schematically showing a gasoline engine as an internal combustion engine to which a cylinder block according to the present invention is applied. It is sectional drawing which shows only a cylinder block along the II-II line | wire of FIG. It is a bottom view of the cylinder block of FIG. It is a bottom view which shows the deformation | transformation aspect of the cylinder block by this invention. It is a bottom view which shows the further deformation | transformation aspect of the cylinder block by this invention. It is a bottom view of the conventional cylinder block.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Gasoline engine (internal combustion engine), 12 ... Cylinder block, 18 ... Crankshaft, 20 ... Bearing part, 24 ... Cylinder, 26 ... Crankcase, 32 ... Crank cap, 38, 38A, 38B ... Reinforcement member, 38a ... No. 1 part, 38b ... 2nd part, 38ba, 38bb ... hypotenuse part, 38bc ... apex part, 44 ... protrusion, 46 ... lubricating oil passage.

Claims (2)

In a cylinder block of an internal combustion engine, comprising a cylinder and a crankcase having a bearing portion that supports a crankshaft, each of the bearing portions being configured by an individual crank cap,
A reinforcing member having a first portion fixed along a free edge of the crank cap and a second portion extending between adjacent first portions and having an intermediate portion fixed to the crankcase. A cylinder block of an internal combustion engine. The second portion has a mountain shape including an oblique side extending obliquely from one of the adjacent first portions and an oblique side extending obliquely from the other of the adjacent first portions, and both oblique sides intersect. The cylinder block of the internal combustion engine according to claim 1, wherein an apex portion is fixed to the crankcase.

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