JP2008175093A - Ladder frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ladder frame for stabilizing the oil level of lubricating oil while securing the strength of the rudder frame. <P>SOLUTION: In a ladder frame 7 of an engine 1 the top surface of which is fastened to the undersurface of a cylinder block 2, and undersurface is fastened to the top surface of an oil pan 4, bulkheads 50 for separating between cylinders are provided to lay across in right angle direction to a crankshaft 10, in inner side of the ladder frame 7, and inverse U-shaped notches 50d are formed at the longitudinal middle lower part of the bulkheads 50. Also, the notches 50d are shaped such that compressive stress will be produced on the notches 50d when internal pressures of cylinders are acting and when bolts are being tightened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique of a spacer (hereinafter referred to as a ladder frame) disposed between a cylinder block and an oil pan, and more particularly, to a structure of a partition wall that improves the strength of a ladder frame and is provided in parallel with a row of cylinders.

Conventionally, a technique is known in which a ladder frame is fixed to the bottom surface of a cylinder block of an engine and is fixed between a bottom surface of the ladder frame and an upper surface of an oil pan via a liquid packing. A partition wall is provided in the ladder frame in parallel with the row of cylinders, and a bearing portion for supporting a crankshaft is provided at the center of the upper longitudinal direction of the partition wall.
On the other hand, when the air in the crank chamber of the cylinder is compressed when the piston of one cylinder descends (when the cylinder internal pressure acts), an internal pressure difference is generated in the crank chamber. In view of this, conventionally, an air hole communicating with the combustion chamber adjacent to the upper portion of the cylinder block is formed to release the compressed air, thereby keeping the internal pressure constant.
JP-A-9-195852 JP 2001-295695 A JP 2003-314358 A

However, the air hole in the upper part of the crank chamber is limited in the maximum area in size in order to maintain the strength.
If the air hole does not have a sufficient area, when the oil pan is filled with lubricating oil, the lubricating oil is pushed up to the wall surface of the crank chamber by the swirling airflow generated in the crank chamber by the rotation of the crankshaft and lubricated. The oil level on the oil inlet is lowered.

  Therefore, in view of such problems, the present invention provides a ladder frame for stabilizing the oil surface of the lubricating oil while ensuring the strength of the ladder frame.

  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, in the engine ladder frame in which the upper surface is fastened to the lower surface of the cylinder block and the lower surface is fastened to the upper surface of the oil pan, a partition that is inside the ladder frame and separates the cylinders is provided. A transverse U-shaped cutout is formed at the central lower portion in the longitudinal direction of the partition wall.

  According to a second aspect of the present invention, the notch is shaped such that a compressive stress is generated in the notch when the cylinder internal pressure is applied and when the bolt is tightened.

  In claim 3, in the ladder frame of the engine, the upper surface is fastened to the lower surface of the cylinder block and the lower surface is fastened to the upper surface of the oil pan, the plate is extended from the inner periphery of the lower end of the ladder frame toward the inner horizontal direction. Is.

  According to a fourth aspect of the present invention, the inner end of the plate is extended to the outside of the outermost rotation locus of the crankshaft.

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

  According to the first aspect of the present invention, even if the air in the crank chamber of one cylinder is compressed when the piston of one cylinder descends (when the cylinder internal pressure is applied), the air can be released into the crank chamber of an adjacent cylinder through a notch. . As a result, fluctuations in the internal pressure in the crank chamber can be suppressed and the oil level can be prevented from undulating. That is, the ladder frame itself can be reduced in weight while preventing air from being sucked into the suction pipe and preventing the hydraulic pressure from decreasing.

  According to the second aspect, since the compressive stress is easily applied to the lower part of the journal, which is a dangerous part of the ladder frame (the tensile stress is difficult to be applied), the safety factor of the lower part of the journal can be improved. This is because the fatigue strength of the FC material is strong against compressive stress and weak against tensile stress.

  According to a third aspect of the present invention, the vertical movement of the oil level is limited by the plate, so that the lubricating oil level is difficult to tilt even if the engine is tilted. Is less likely to occur. That is, it is possible to prevent the oil surface from wavy, to prevent air from being sucked into the suction pipe, and to prevent the hydraulic pressure from being lowered. Moreover, the torsional rigidity of the ladder frame itself is improved by the plate, and noise can be reduced.

  According to the fourth aspect of the present invention, the vertical movement of the oil level caused by the rotation of the crankshaft can be limited by the plate without interfering with the crankshaft. That is, it is possible to prevent the oil surface from wavy, to prevent air from being sucked into the suction pipe, and to prevent the hydraulic pressure from being lowered. Further, the plate can be made as large as possible, the torsional rigidity of the ladder frame itself can be improved, and noise can be reduced.

Next, embodiments of the invention will be described.
FIG. 1 is a left side view of an engine having a radiator according to the present invention, FIG. 2 is a front view of the engine, and FIG. 3 is a partial front sectional view showing a ladder frame and an oil pan. 4 is a perspective view showing a ladder frame, FIG. 5 is a bottom view showing the ladder frame, FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5, and FIG. 7 is a perspective view showing stress distribution of the ladder frame during an internal pressure action. FIG. 8 is a perspective view showing the stress distribution of the ladder frame during bolt tightening, FIG. 9 is a graph showing the fatigue strength of the FC material, and FIG. 10 is a perspective view showing the stress distribution of the conventional ladder frame during internal pressure action. FIG. 11 and FIG. 11 are perspective views showing the stress distribution of a conventional ladder frame during bolt tightening.

First, a schematic configuration of an engine 1 having a radiator 30 according to an embodiment of the present invention will be described with reference to FIG. In the following description, the right side of FIG. 1 is assumed to be the front and the near side is assumed to be the right side.
In the engine 1, a cylinder block 2 is located at the center, a cylinder head 3 is placed and fixed on the upper side of the cylinder block 2, and an oil pan 4 is placed on the lower side of the cylinder block 2 via a ladder frame (spacer) 7. Is arranged. On one side of the cylinder block 2 (right side in the present embodiment), a fuel injection pump 22 and a filter 5 for filtering oil used in a crankcase (not shown) are disposed. A flywheel (not shown) is integrally fixed to a rear end portion (left end portion in FIG. 1) of the crankshaft 10 of the engine 1, and the flywheel is covered with a flywheel cover 16. Yes.

  A gear case 8 including a cam mechanism and the like for driving the fuel injection pump 22 is attached to the front surface of the engine 1 body, and the front surface is covered with a gear case cover 6. A driving pulley 11 is integrally fixed to the front end portion of the crankshaft 10 in front of the gear case cover 6. A driven pulley 12 is pivotably supported above the drive pulley 11, and a radiator fan 31 is integrally fixed to the front end portion of the rotating shaft 17 of the driven pulley 12. A tension pulley 13 is pivotally supported to the left of the driven pulley 12 and the drive pulley 11. Around these pulleys 11, 12, and 13, a belt 15 composed of a V belt or the like is wound, and the driving force of the driving pulley 11 is transmitted to the driven pulley 12 and the tension pulley 13 via the belt 15. Thus, the radiator fan 31 fixed to the rotating shaft 17 of the driven pulley 12 is driven.

  The tension pulley 13 is integrally fixed to a drive shaft 20a of an alternator 20 that is one of engine accessories, and the alternator 20 serves as a mounting flange 20b having a part of the cover as a support portion of the tension pulley 13. The lower part is supported by a supporting part provided on the gear case cover 6 by an attachment fulcrum 21 such as a bolt.

Next, the mounting structure of the oil pan 4 to the engine 1 will be described in detail. The mounting structure of the oil pan 4 to the ladder frame 7 below the cylinder block 2 will be described.
As shown in FIG. 1, an oil pan 4 is provided below the cylinder block 2, and lubricating oil is stored in the oil pan 4. Specifically, the ladder frame 7 is fixed to the lower part of the cylinder block 2 with bolts or the like, and the oil pan 4 is fixed to the lower part of the ladder frame 7 with bolts or the like. The ladder frame 7 extends from below the rear end of the cylinder block 2 to below the gear case cover 6, and the gear case 8 attached to the front part of the cylinder block 2 is also connected to the ladder frame 7.

Specifically, the oil pan 4 has a bolt hole (not shown) formed on the outer periphery in plan view, and the bolt is screwed into the bolt hole to fix the oil pan 4 to the ladder frame 7 via the liquid packing. It is the composition to install. The oil pan 4 has a substantially rectangular shape in plan view, and is formed in a container having an upper opening. The oil pan 4 is manufactured by forming a cold rolled steel sheet or the like as a mold.
The oil pan 4 is provided with a drain 23 in the lower right part in a rear view so that the lubricating oil mixed with impurities or oxidized after a certain period of time can be discharged from the oil pan 4. .

  Bolt holes 50a are formed on the outer periphery of the ladder frame 7 in plan view, and bolt holes 50b for oil pans are formed further outside. Then, a bolt is screwed from below the bolt hole to fix the ladder frame 7 to the cylinder block 2, and the bolt hole formed in the oil pan 4 is aligned with the bolt hole for oil pan formed in the ladder frame 7. Thus, the bolt is screwed from below with the outer periphery of the oil pan 4 being in close contact with the outer periphery of the ladder frame 7.

  As shown in FIGS. 1 and 2, support legs 38 and 38 are fixed to the side surface of the front lower portion of the engine 1 (the cylinder block 2 or the ladder frame 7) by bolts or the like. Specifically, the support legs 38 are steel members formed in a substantially “<” shape in a side view, and the rear part thereof is fixed to the front lower part of the engine 1 with a bolt or the like so that the front of the engine 1 They extend in parallel from the lower part toward the front lower part.

Next, the structure of the ladder frame 7 will be described with reference to FIGS.
As shown in FIG. 3, the ladder frame 7 is attached to the lower portion of the cylinder block 2 with bolts, and is configured to secure a space (crank chamber 51) for supporting the crankshaft 10. As shown in FIG. 3, the crankshaft 10 is connected to a connecting rod 70, and is configured to take the output by converting the vertical movement of the piston into a rotational movement. As shown in FIG. 4, a plurality of partition walls 50 for supporting the crankshaft 10 are provided on the inner side of the ladder frame 7, and the partition walls 50 are also provided at the bottom of the cylinder block. A plurality of bolt holes 50a for inserting bolts for fastening with the provided partition walls (not shown) are provided. On the other hand, the lower surface of the ladder frame 7 is provided with a plurality of bolt holes 50 b for inserting bolts for fixing the oil pan 4.

Further, as shown in FIGS. 4 and 6, the partition wall 50 of the ladder frame 7 is provided with a bearing portion 50c for supporting the crankshaft 10 at the center in the upper longitudinal direction. The journal of the crankshaft 10 is supported by a partition wall (bearing portion) (not shown) provided on the lower surface of the cylinder block 2. Further, the crank chamber 51 is partitioned for each cylinder by the partition wall 50.
On the other hand, as shown in FIGS. 3 and 4, the partition wall 50 of the ladder frame 7 is provided with a substantially semi-elliptical cutout portion 50 d at the lower center in the longitudinal direction of the partition wall 50. The upper end position of the notch 50d is higher than the upper limit position when the oil pan 4 is filled with lubricating oil. By providing the notch 50d as shown in FIG. 3, when the inside of the crank chamber 51 of a certain cylinder is compressed, the compressed air is released into the crank chamber 51 of the adjacent cylinder via the notch 50d. be able to. With such a configuration, even when the air in the crank chamber 51 of the cylinder is compressed when the piston of one cylinder descends (when the cylinder internal pressure is applied), a notch is formed in the crank chamber 51 of the adjacent cylinder. Can escape via 50d. As a result, fluctuations in the internal pressure in the crank chamber 51 can be suppressed, and the oil surface can be prevented from wavy. That is, it is possible to reduce the weight of the ladder frame 7 while preventing the oil level from being lowered by the increase of the internal pressure and preventing the air from being sucked into the suction pipe, thereby preventing the hydraulic pressure from being lowered.

  As shown in FIG. 4, the notch 50d is formed in an inverted U shape when viewed from the front. With this configuration, an average compressive stress is generated around the notch portion 50d when the cylinder internal pressure is applied and when the bolt is tightened, and no stress concentration occurs. The ladder frame 7 is made of FC material (cast iron). As shown in FIG. 9, the FC material has high fatigue strength against compressive stress, but low fatigue strength against tensile stress. Therefore, there is a demand for a shape that generates as much compressive stress as possible in the ladder frame 7 without generating tensile stress.

The effect on the stress distribution when the notch 50d is provided in the partition wall 50 of the ladder frame 7 according to the present invention will be described.
First, FIG. 10 and FIG. 11 show the stress distribution during the internal pressure action and the bolt tightening in the conventional partition wall shape. 10 and 11, the hatched portion represents the tensile stress, and the shaded portion represents the portion subjected to the compressive stress.
In the conventional shape of the partition wall 150, a bearing portion 150c for supporting the crankshaft 10 is provided at the center in the upper longitudinal direction, but a notch portion is not provided in the center in the lower longitudinal direction, and the lower portion of the partition wall 150 is provided. Is formed in a straight line. As shown in FIG. 10, in the ladder frame 107 having the partition wall 150, compressive stress is generated at the joint between the partition wall 150 and the ladder frame 107 when the internal pressure is applied, but the partition wall 150 has an overall tensile stress. is working. In addition, as shown in FIG. 11, at the time of bolt tightening, although a portion where compressive stress is applied around the bolt hole 150 a can be confirmed, tensile stress acts on most of the partition wall 150, and the ladder frame 107 is configured. There is a high possibility that the FC material will cause metal fatigue.

On the other hand, FIG.7 and FIG.8 is the figure which showed the stress distribution at the time of internal pressure effect | action at the time of providing the notch part 50d, and a bolt fastening. 7 and 8, the hatched portion represents the tensile stress, and the shaded portion represents the portion subjected to the compressive stress.
As shown in FIG. 7, when the internal pressure is applied, the outer peripheral portion of the ladder frame 7 is almost subjected to compressive stress, and the bottom side of the partition wall 50 is also subjected to compressive stress. On the other hand, as shown in FIG. 8, at the time of bolt tightening, there are many portions receiving tensile stress. However, there are portions that receive compressive stress around the bolt hole 50a and around the bearing portion 50c that supports the journal of the crankshaft 10. That is, it is understood that the compressive stress due to the bolt tightening works up to the vicinity of the bearing portion at the center in the upper longitudinal direction of the partition wall 50 by configuring the notch portion in an inverted U shape.
By configuring in this way, since the compressive stress is applied to the vicinity of the bearing portion corresponding to the lower portion of the journal of the ladder frame 7 (the tensile stress is hardly applied), the safety factor of the lower portion of the journal can be improved.

  As shown in FIGS. 5 and 6, a plate 52 is provided between the partition wall 50 and the partition wall 50 below the ladder frame 7 so as to extend from both left and right sides (longitudinal direction of the partition wall 50) toward the center. ing. That is, the plate 52 extends to the center side from the inside of the side surfaces on both the front and rear sides of the ladder frame 7 and the inner peripheral surfaces on both left and right sides between the partition walls 50 and from the inner peripheral surfaces on both left and right sides between the partition walls 50 and 50. The inner ends thereof are located at both end positions of the notch 50d, and have a substantially arc shape in plan view. In other words, the plate 52 extends to a position where it does not interfere with the rotation of the lower part of the connecting rod that is pivotally supported by the crankshaft 10. The plate 52 extends from the inner periphery of the lower end of the ladder frame 7 toward the inner horizontal direction. The place where the plate 52 is extended forms a surface higher than the bottom surface of the ladder frame 7 depending on the thickness of the plate 52, and is near the upper limit position when the lubricating oil is filled. The plate 52 is formed by a mold together with the ladder frame 7. By configuring in this way, even if the oil level moves up and down due to the raising and lowering of the piston, the inclination of the main body of the engine 1, etc., the oil level hits the plate 52 and the fluctuation is limited. Is less likely to occur. That is, it is possible to prevent the oil surface from wavy, to prevent air from being sucked into the suction pipe, and to prevent the hydraulic pressure from being lowered.

  Further, as shown in FIG. 6, the inner end of the plate 52 is configured to be located outside the outermost rotation locus of the crankshaft 10 represented by a two-dot chain line. With this configuration, the inner end of the plate does not interfere with the crankshaft 10, so that even if the oil level moves up and down due to the rotation of the crankshaft 10, it flows from between the plate 52 and the crankshaft. It becomes difficult to limit the oil level change. That is, it is possible to prevent the oil surface from wavy, to prevent air from being sucked into the suction pipe, and to prevent the hydraulic pressure from being lowered. Further, the plate 52 can be made as large as possible, the torsional rigidity of the ladder frame 7 itself can be improved, and noise can be reduced.

  As described above, the ladder frame 7 according to the present invention has a top surface fastened to the bottom surface of the cylinder block 2 and a bottom surface fastened to the top surface of the oil pan 4. A partition wall 50 for separating the cylinders is provided horizontally in a direction perpendicular to the crankshaft 10, and an inverted U-shaped notch 50 d is formed at the lower center of the longitudinal direction of the partition wall 50. With this configuration, even when the air in the crank chamber of one cylinder is compressed when the piston of one cylinder descends (when the cylinder internal pressure is applied), the air is released into the crank chamber of an adjacent cylinder through a notch. Can do. As a result, fluctuations in the internal pressure in the crank chamber can be suppressed and the oil level can be prevented from undulating. That is, the ladder frame itself can be reduced in weight while preventing air from being sucked into the suction pipe and preventing the hydraulic pressure from decreasing.

  Further, the notch 50d is shaped so that compressive stress is generated in the notch 50d when the cylinder internal pressure is applied and when the bolt is tightened. By configuring in this way, it becomes easy to apply compressive stress to the lower part of the journal, which is a dangerous part of the ladder frame (it is difficult to apply tensile stress), and thus the safety factor of the lower part of the journal can be improved. This is because the fatigue strength of the FC material is strong against compressive stress and weak against tensile stress.

  Further, in the ladder frame 7 of the engine 1, the upper surface is fastened to the lower surface of the cylinder block 2 and the lower surface is fastened to the upper surface of the oil pan 4, the plate 52 is extended from the inner periphery of the lower end of the ladder frame 7 toward the inner horizontal direction. It is set. With this structure, the plate restricts the vertical movement of the oil level, so that even if the engine is tilted, the lubricating oil level is difficult to tilt. Differences in elevation are less likely to occur. That is, it is possible to prevent the oil surface from wavy, to prevent air from being sucked into the suction pipe, and to prevent the hydraulic pressure from being lowered. Moreover, the torsional rigidity of the ladder frame itself is improved by the plate, and noise can be reduced.

  Further, the inner end of the plate is extended to the outside of the outermost rotation locus of the crankshaft. By configuring in this way, it is possible to limit the vertical movement of the oil surface caused by the rotation of the crankshaft by the plate without interfering with the crankshaft. That is, it is possible to prevent the oil surface from wavy, to prevent air from being sucked into the suction pipe, and to prevent the hydraulic pressure from being lowered. Further, the plate can be made as large as possible, the torsional rigidity of the ladder frame itself can be improved, and noise can be reduced.

The left view of the engine which has a radiator concerning the present invention. The front view of an engine. The front fragmentary sectional view which shows a ladder frame and an oil pan. The perspective view which shows a ladder frame. The bottom view which shows a ladder frame. AA sectional drawing in FIG. The perspective view showing the stress distribution of the ladder frame at the time of internal pressure action. The perspective view showing the stress distribution of the ladder frame at the time of bolt fastening. The graph showing the fatigue strength of FC material. The perspective view showing the stress distribution of the conventional ladder frame at the time of an internal pressure effect | action. The perspective view showing the stress distribution of the conventional ladder frame at the time of bolt fastening.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 4 Oil pan 7 Ladder frame 50 Bulkhead 50a Bolt hole 50c Bearing part 50d Notch part 51 Crank chamber 52 Plate

Claims (4)

  In the engine ladder frame, the upper surface is fastened to the cylinder block lower surface and the lower surface is fastened to the oil pan upper surface, the partition wall that is inside the ladder frame and separates the cylinders is horizontally mounted in a direction perpendicular to the crankshaft. A ladder frame characterized in that an inverted U-shaped notch is formed at the lower center in the longitudinal direction of the partition wall. The notch,
The ladder frame according to claim 1, wherein a compression stress is generated in the notch when a cylinder internal pressure is applied and when a bolt is tightened.   In the ladder frame of the engine, the upper surface is fastened to the lower surface of the cylinder block and the lower surface is fastened to the upper surface of the oil pan, the ladder is characterized in that the plate extends from the inner periphery of the lower end of the ladder frame toward the inner horizontal direction. flame.   The ladder frame according to claim 3, wherein an inner end of the plate is extended to an outer side of an outermost rotation locus of the crankshaft.

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