JP2024005736A - Crank shaft support structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crank shaft support structure capable of constituting a beam-integrated bearing cap without increasing the size of a crank case with further structural improvements, to improve strength and rigidity of a crank case.

SOLUTION: A crank shaft support structure is provided with a bearing cap body B in which a plurality of bearing caps 18 for pivotally supporting a crank shaft 5 at a lower part of a cylinder block 1 is integrated with a beam 19 extending in an axial core P direction of the crank shaft 5. The beam 19 is configured to have a cross section along or similar to a cross-sectional shape of a gap S, where the gap S is an outside region of a rotational trajectory t of the crank shaft 5 and an inside region of a lower crank case 1C assembled under the cylinder block 1.

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a crankshaft support structure for an engine equipped with a bearing cap that supports a crankshaft bearing from below.

Generally, in industrial and automobile engines, a cylinder block is used in which a cylinder part and a crankcase part are integrated, as disclosed in Patent Document 1, and the lower part of the cylinder block, that is, the crankcase part, is used. The crankshaft provided in the case part is pivotally supported by a journal part machined into the upper part of the crankcase part and a bearing cap assembled to the central lower surface of the crankcase part.

For example, in multi-cylinder diesel engines that are intended to be mounted on agricultural tractors, the crankcase section (lower part of the cylinder block) is often structured to also serve as the body frame of the tractor (see Patent Document 1, etc.). The crankcase section requires strength and rigidity. That is, when using a crankcase portion that also serves as the fuselage frame, a lower crankcase 57 is often provided in order to provide sufficient strength and rigidity, as shown in the schematic diagram in FIG. 7(B).

In FIG. 7(B), 51 is a cylinder block, 51A is a cylinder part, 51B is a crankcase part, 52 is a piston, 53 is a connecting rod, and 54 is a crankshaft. A bearing cap 55 for supporting the shaft 54 is fixed with a bolt 56. An open box-shaped (concave) lower crankcase 57 is attached to the lower surface of both left and right ends of the crankcase portion 51B by bolts so as to cover the bearing cap 55.

In other words, by assembling and integrating the lower crankcase 57, which is a strength member, under the crankcase part 51B, the strength and rigidity of the crankcase part k is increased so that it can function as the fuselage frame. It was said to be a composition.

JP2021-085356A Japanese Patent Application Publication No. 2018-184171

When increasing engine output while maintaining the conventional structure due to specification changes or new development, the burden (behavior) on the bearing cap increases due to the increase in combustion load (increase in explosion pressure), so some kind of countermeasure is required. It has become. Possible countermeasures include integrating the bearing cap into the lower crankcase or adding a beam to the bearing cap.

The former plan (integrating the bearing cap and the lower crankcase) is large-scale and costly, and is extremely difficult to realize, so the latter plan is more realistic. However, when adding a beam, which has a cost advantage, the bearing cap is covered with the lower crankcase with little clearance, so it is possible to add a new beam without increasing the size of the lower crankcase or crankcase section. It is not easy [see Figure 7(B)].

In view of the above circumstances, the purpose of the present invention is to focus on the latter option (addition of a beam) which is more cost-effective out of the above two options, and to increase the size of the crankcase through further structural innovation. An object of the present invention is to provide a crankshaft support structure that can improve the strength and rigidity of a crankcase by making it possible to construct a bearing cap body with an integrated beam.

The present invention provides a crankshaft support structure including:
A bearing cap body is provided in which a plurality of bearing caps that pivotally support a crankshaft at a lower part of a cylinder block are integrated with a beam extending in the axial direction of the crankshaft,
The beam has a shape similar to or similar to the cross-sectional shape of the gap, which is an area outside the rotation locus of the crankshaft and an inside area of the lower crankcase assembled under the cylinder block. It is characterized by being configured to have a cross section of .

In this case, it is advantageous that the peak portion of the beam corresponding to the maximum rotation locus of the crankshaft is set to have a cross-sectional shape having an inner diameter close to the maximum rotation locus. For other aspects of the present invention, please refer to claims 3 to 5 of the claims.

According to the present invention, beams are installed in the rotation locus of the crankshaft (rotation locus of the big end and counterweight), the bolt seating surface of the bearing cap, and the triangular part (gap area) covered by the lower crankcase, and the bearing A bearing cap body is constructed by connecting the cap and the beam. Since the beam has a cross-sectional shape that follows or is similar to the cross-sectional shape of the gap, it is possible to have a larger cross-sectional area than before without changing the lower crankcase.

Therefore, by adding a beam, the combustion load that was borne by four bolts in the past when the bearing caps were independent from each other can now be borne by the bolts of the adjacent bearing cap, reducing the behavior of the bearing cap and causing vibrations.・Deterioration of noise can be suppressed.

As a result, a beam-integrated bearing cap body can be constructed without increasing the size of the lower crankcase (crankcase), thereby providing a crankshaft support structure that can improve the strength and rigidity of the crankcase at a low cost. be able to.

Left side view of an industrial in-line multi-cylinder diesel engine Front view of the engine shown in Figure 1 Side view showing the general flow of cooling water in the engine Showing the bearing cap body, (A) is a plan view, (B) is a front view, and (C) is a sectional view taken along the Z-Z line in (A). Front view of main parts showing crankshaft support structure (A) is a plan view of the lower crankcase, and (B) is a diagram of the main parts seen in the direction of arrow Y in Figure 5, showing the relationship between the beam and the crankshaft. The characteristic structure of the crankshaft support structure is shown, (A) is a schematic diagram of the present invention, and (B) is a conventional schematic diagram.

Embodiments of the crankshaft support structure according to the present invention will be described below with reference to the drawings for an industrial in-line multi-cylinder diesel engine. In an industrial diesel engine (hereinafter referred to as engine) E, the side with the cooling fan 10 is the front, the side with the flywheel 7 (flywheel housing 7A) is the rear, the side with the exhaust manifold 31 is the left, and the exhaust The side without the manifold 31 (the side with the intake manifold (not shown)) is the right side.

As shown in FIGS. 1 to 3, in an engine [a vertical in-line four-cylinder (multi-cylinder) water-cooled engine] E, a cylinder head 2 is assembled on a cylinder block 1, and a head cover is mounted on the cylinder head 2. 3 is assembled, and an oil pan 4 is assembled under the cylinder block 1. 5 is a crankshaft, 6 is a piston, 7 is a flywheel, 8 is a transmission belt, 9 is a water pump, 10 is a cooling fan, and 11 is a radiator. 32 is a supercharger, and 33 is an exhaust treatment device.

The upper part of the cylinder block 1 is formed into a cylinder part 1A into which the piston 6 is fitted, and the lower side of the cylinder part 1A is formed into a crankcase part C. The crankcase part k is composed of an upper crankcase 1B integrally formed with the cylinder part 1A, and a lower crankcase 1C (see also FIG. 6(A)) assembled under the upper crankcase 1B. . The oil pan 4 is assembled under the lower crankcase 1C.

As shown in FIG. 3, the crankshaft 5 is pivotally supported by an upper crankcase 1B and a bearing cap body B assembled under the upper crankcase 1B with a plurality of bolts. That is, the lower crankcase 1C and the bearing cap body B are assembled on the lower surface of the upper crankcase 1B, and the bearing cap body B is configured to be housed inside the lower crankcase 1C without any gaps. has been done.

As shown in FIGS. 4 and 5, the bearing cap body B includes a plurality of bearing caps (bearing cap portions) 18 arranged in front and back (5 locations) and a plan in which adjacent bearing caps 18 are connected and integrated. It is configured into a substantially ladder-like structure (see FIG. 4(A)) having eight beams (beam portions) 19. That is, a bearing cap body B is provided in which a plurality of bearing caps 18 that pivotally support the crankshaft 5 at the lower part of the cylinder block 1 are integrated by a beam 19 extending in the direction of the axis P of the crankshaft 5.

Each bearing cap 18 is bolted to the lower surface of a plurality of bearing walls 20 hanging from the upper crankcase 1B at two locations on the left and right. That is, the bearing cap body B is attached to the upper crankcase 1B by ten bolts 21 (see FIG. 7(A)).

The bearing cap 18 is formed by equipping a cap body 18A with a semicircular inner circumferential surface 18a on which a bearing (sliding bearing, etc.) 22 is placed, and a pair of left and right mounting seating surfaces 18b. A beam 19 is connected to each. The bearing 22 is a portion that pivotally supports the journal 5a of the crankshaft 5, and is also attached to a journal portion (not shown) at the bottom of the bearing wall 20 (see FIG. 5).

As shown in FIGS. 4, 5, and 6B, the beam 19 has a front beam part 19a and a rear beam part 19b that are continuous with the bearing cap 18, and an intermediate part 19c. In addition, in the four beams 19 on the left and right sides of the front and rear ends, the front beam part 19a and the rear beam part 19b are formed into a diagonal beam-like shape to restrict the overhang to the left and right [Fig. 4 ( See A). The beam 19 has a cross-section along or similar to the cross-sectional shape of the gap S, which is an area outside the rotation locus t of the crankshaft 5 and an inside area of the lower crankcase 1C. (See Figure 5).

In the crankshaft 5, the locations where the rotation locus t becomes large include the large end 23A of the connecting rod 23 that pivotally supports the piston 6 at the upper end, and the counters located close to both sides (front and rear) of the large end 23A. Among the weights 24, 24, the location where the rotation locus (rotation radius) is the largest (maximum rotation locus st) is the large end portion 23A. Therefore, in order to avoid interference with the pair of counterweights 24, 24 and the large end portion 23A, the beam 19 is directed to the side inner surface 19s located outside the rotation locus (maximum rotation locus) t of the three counterweights 24, 23A, 24. , 19s and a central inner surface 19d, and is formed into a substantially V-shape (substantially U-shape) when viewed in the left-right direction [see FIG. 6(B)].

As shown in FIGS. 1, 2, 5, and 6A, the lower crankcase 1C has a front wall 25, a rear wall 26, a left wall 27, a right wall 28, and a bottom wall 29 located between the front and back. Further, reinforcing rib walls 30 extending left and right are formed at three locations in the front and rear corresponding to the bearing wall 20. The front wall 25 and the rear wall 26 are formed with notches 25A and 26A (see FIG. 6A) that are recessed downward from the upper end at the left and right center portions to allow the crankshaft 5 to pass therethrough.

As shown in FIG. 5, the left and right outer surfaces 19L and 19R of each beam 19 are set to closely follow the corresponding left and right inner surfaces 27A and 28A of the lower crankcase 1C, and each beam The bottom surface 19B of the bottom wall 29 is set to closely follow the top surface 29A of the bottom wall 29. In addition, the central inner surface 19d, which is the upper surface (slanted upper surface) of the intermediate portion 19c located at the maximum rotation locus st where the rotation locus t is maximum in the front-rear direction, is set to closely follow the rotation locus t. ing. As a result, the intermediate portion 19c has an irregular quadrangular cross-sectional shape having a left outer surface 19L, a right outer surface 19R, an inclined central inner surface 19d, and short sides 19e on the left and right center sides.

In other words, an intermediate portion (an example of a "peak point") 19c corresponding to the maximum rotation locus st of the crankshaft 5 in the beam 19 has a cross section having a central inner surface (an example of a "radial inner surface") 19d that is close to the maximum rotation locus st. It is set to shape. Then, the cross-sectional area of the beam 19 (the area of the cross-section cut in the left-right direction) is set to gradually increase as it goes forward and backward (as it goes toward the connection part to the bearing cap 18) from the intermediate part 19c, which is the peak point. has been done. The intermediate portion 19c has outer surfaces 19L, 19R along the inner surfaces 27A, 28A of the lower crankcase 1C, and a bottom surface 19B along the upper surface 29A of the lower crankcase 1C.

The left-right width of the intermediate portion 19c, that is, the position of the short side surface 19e in the left-right direction, is set such that stress concentration is unlikely to occur in the intermediate portion 19c (so that the bottom surface 19B and the central inner surface 19d do not directly intersect and form an acute-angled tip). ), the length is set to be short enough to ensure a rectangular cross section with a certain length. It can also be said that the short side surface 19e is provided at a position as close to the inside in the left-right direction as possible within the range in which the bolt (not shown) that attaches the bearing cap 18 to the bearing wall 20 can be attached and removed and the turning tool can be operated. .

[About effects]
Since the lower crankcase 1C is attached to the upper crankcase 1B, the strength and rigidity of the crankcase part k is greatly improved, and the crankcase part k can be suitably used in working machines (such as agricultural tractors) that also serve as the body frame. can. Since a beam 19 is provided that connects and integrates adjacent bearing caps 18 for pivotally supporting the crankshaft 5, the strength and rigidity of the bearing caps 18 are improved, and the combustion load is increased by increasing the output. However, the behavior of the bearing cap 18 (bearing cap body B) no longer increases.

In the present invention, as shown in FIG. 7(A), the cross-sectional area is as large as possible in the outer region of the maximum rotation locus st of the crankshaft 5 and within the inner region of the lower crankcase (liner case) 1C. Since the beam is provided so that it can be removed, a beam 19 with strength and rigidity can be constructed without changing the size of the lower crankcase 1C, and therefore, the bearing cap body B can have sufficient strength and rigidity. was completed. In FIG. 7(A), the hatched approximately triangular portions on the left and right sides indicating the gap S are drawn to include the space where the head of the bolt 21 (notation is omitted) is placed. In the part where there is no part, the upper surface 29A (see FIG. 5) of the lower crankcase 1C approaches the bottom of the bearing cap 18, and the aforementioned substantially triangular part becomes even smaller as its bottom rises to the bottom of the bearing cap 18. There is.

In other words, the beam 19 is located at the triangular portion (gap portion S) covered by the rotation locus t of the crankshaft 5 (such as the rotation locus of the large end 23A and the counterweight 24), the bolt seating surface of the bearing cap 18, and the lower crankcase 1C. was installed, and the bearing cap body B was constructed by connecting the bearing cap 18 and the beam 19.
By adding the beam 19, the combustion load that was borne by four bolts in the past when the bearing caps were independent from each other can now be borne by the bolt 21 of the adjacent bearing cap, and the behavior of the bearing cap 18 can be reduced. Deterioration of vibration and noise can be suppressed.

As shown in FIG. 6(B), the shape of the beam 19 is such that the front and rear beam portions 19a and 19b are formed such that the cross-sectional area increases from the intermediate portion 19c toward the bearing cap 18. Therefore, the portion with the minimum cross-sectional area is only the intermediate portion 19c, which greatly improves the strength and rigidity of the beam 19, and as a result, there is also the advantage that the strength and rigidity of the bearing cap body B are also greatly improved.

[Another embodiment]
The cross-sectional shape of the intermediate portion 19c (corresponding to the maximum rotation locus st) of the beam 19 is made closer to the inner surface of the lower crankcase 1C and the maximum rotation locus st within the range that allows for the dimensional tolerance of the gap between parts to increase the area. You can also do this.

1 Cylinder block 1C Lower crankcase 5 Crankshaft 18 Bearing cap 19 Beam 19L, 19R Outer surface 19c Peak location 19d Diameter inner surface 27A, 28A Inner surface B Bearing cap body P Axial center S Gap location t Rotation trajectory st Maximum rotation trajectory

Claims (5)

A bearing cap body is provided in which a plurality of bearing caps that pivotally support the crankshaft at the lower part of the cylinder block are integrated with a beam extending in the axial direction of the crankshaft,
The beam is located at a gap location that is an area outside the rotational locus of the crankshaft and an inside area of the lower crankcase assembled under the cylinder block, and has a shape that is along or similar to the cross-sectional shape of the gap area. A crankshaft support structure configured to have a shaped cross section. 2. The crankshaft support structure according to claim 1, wherein a peak portion of the beam corresponding to a maximum rotation locus of the crankshaft is set to have a cross-sectional shape having an inner diameter close to the maximum rotation locus. 3. The crankshaft support structure according to claim 2, wherein the cross-sectional area of the beam is set to gradually increase from the peak point to the connection point to the bearing cap. 3. The crankshaft support structure according to claim 2, wherein the peak portion has an outer surface along an inner surface of the lower crankcase and a bottom surface along an upper surface of the lower crankcase. The crankshaft support structure according to any one of claims 1 to 4, wherein the beams are provided on the left and right sides of the axis of the crankshaft.

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