JP2006161639A - Rudder frame structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide rudder frame structure capable of reducing weight of a rudder frame without hindering rigidity and function of the rudder frame. <P>SOLUTION: In the rudder frame structure structured by connecting both ends of a plurality of bearing caps 2, which are fastened to a lower surface of a cylinder block 5, with a side wall 3, height of a cap part 2a of the bearing cap 2 is set at, at least, a height regulated by the maximum load by the maximum combustion pressure of an engine cylinder, and a lower end of the side wall is provided in a part higher than the lower end of the cap part, and the lower ends of the cap part and the side wall are connected to each other by a wall surface 2f directed obliquely upward from a lower end 2a' of the cap part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ladder frame structure in which both ends of a plurality of bearing cap portions fastened to a lower surface of a cylinder block of an engine are connected by side walls.

  A mounting flange portion formed at the peripheral edge of the opening of the oil pan is attached to the lower surface of a crankcase outer wall portion (hereinafter referred to as “skirt portion”) that forms a crankcase of an engine cylinder block. The flange on the lower surface of the crankcase has a low rigidity because the lower surface of the crankcase is a large opening, and is particularly vulnerable to left and right and vertical vibrations of the crankcase. It has become. Therefore, as a method of reducing engine vibration and noise, a ladder frame structure is generally employed that increases the rigidity of the crankcase (hereinafter referred to as “skirt portion”) below the cylinder block.

  In the ladder frame structure, the side walls of the crankcase are integrally connected in the front-rear direction at both side ends of a plurality of bearing caps fastened to the lower edge of the cylinder block at the side walls connected to the cylinder block skirt. A structure has been proposed in which a thick wall portion is provided at the lower edge, and a fire striking portion is formed integrally at the corner where the thick wall portion and the bearing cap portion intersect each other at an angle (for example, a patent) Reference 1).

Alternatively, a structure has been proposed in which the cross-sectional shape of the wall surface between the plurality of bearing cap portions of the ladder frame structure is reinforced by forming an arc shape corresponding to the rotation trajectory of the crankshaft (for example, Patent Documents). 2).
Japanese Utility Model Publication No.59-552 Japanese Patent Laid-Open No. 10-266892

However, the ladder frame structure disclosed in Patent Document 1 cannot be expected to have an effect unless the thickness of the thick portion is made sufficiently thick, and the ladder frame structure is less than the effect of reducing engine vibration and noise. There is a problem that the weight of the frame increases.
Further, the ladder frame structure disclosed in Patent Document 2 increases the area of the arc-shaped wall surface corresponding to the rotation trajectory of the crankshaft and the corresponding bearing cap and skirt portion, thereby increasing the weight of the entire ladder frame. Will increase. For this reason, there are problems such as restrictions on the load capacity of the vehicle due to an increase in the weight of the engine, deterioration in fuel consumption, and an increase in manufacturing cost.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a ladder frame structure capable of reducing the weight of the ladder frame without impairing the rigidity and function of the ladder frame.

  In order to achieve the above object, the ladder frame structure according to claim 1 is a ladder frame structure in which both ends of a plurality of bearing caps fastened to the lower surface of the cylinder block are connected by side walls, and the height of the cap portion of the bearing cap is set. The height is set at least by the maximum load defined by the maximum combustion pressure of the cylinder of the engine, the lower end of the side wall is provided above the lower end of the cap part, and the cap part and the lower end of the side wall are provided in the cap part. It is made into the structure connected by the wall surface which goes diagonally upwards from the lower end of.

  By reducing the height of the side wall and forming a wall surface obliquely upward from the cap portion toward the lower end of the side wall, the area of the wall surface portion (partition wall surface) of the bearing cap is reduced. Further, by positioning the flange portion of the oil pan above the lower end of the cap portion, the area occupied by the side wall in the height direction is reduced. Thereby, the weight ratio of the partition wall and the side wall occupying the entire ladder frame is reduced, and the weight can be reduced without impairing the rigidity and function of the ladder frame structure that suppresses the vibration of the side wall as the skirt.

The ladder frame structure according to claim 2 is the ladder frame structure according to claim 1, wherein a through hole is provided in the side wall, and a bolt for fastening the ladder frame to the cylinder block is inserted into the through hole. Yes.
The rudder frame is arranged so that the bearing cap pivotally supports the journal of the crankshaft below the main cap of the cylinder block, the mounting flange at the upper end of the side wall is in contact with the mounting flange of the cylinder block via a gasket, and the main bolt Is fixed to the main cap, and the side wall is fixed to the cylinder block by the sub bolt. Thereby, a subbolt can be shortened.

  An oil pan is disposed below the ladder frame, and the mounting flange of the oil pan is fixed to the mounting flange at the lower end of the side wall by a bolt via a gasket. The side wall is reduced above the height of the cap part, and the mounting flange of the oil pan is attached above the height of the cap part of the bearing cap. Thereby, the position of the oil pan can be increased, and the length of the engine in the height direction can be reduced.

  According to the ladder frame structure of claim 1, by forming the wall surface obliquely upward from the cap portion toward the lower end of the side wall, the area of each wall surface portion (partition wall surface) is reduced, and the rigidity and function of the ladder frame are increased. Weight can be reduced without loss. This also reduces the amount of material used to make the ladder frame and can reduce manufacturing costs.

  Further, according to the ladder frame structure of claim 2, the height of the side wall of the ladder frame can be reduced, so that the length of the sub-bolt necessary for attaching the ladder frame can be shortened, and the weight of the bolt can be reduced. The weight of the entire engine can be reduced in combination with the weight reduction of the ladder frame.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a front view of a ladder frame structure according to the present invention, and FIG. 2 is a perspective view of FIG. As shown in FIGS. 1 and 2, the ladder frame 1 has a structure in which left and right ends of a plurality of bearing caps 2 are integrally connected by side walls 3 and 3. The cap portion 2a has a flat upper surface 2b, and a semicircular bearing surface 2c for pivotally supporting the journal of the crankshaft is formed at the center. The height H of the cap portion 2a is set to a height (thickness) necessary for the strength defined by at least the maximum combustion pressure of the cylinder of the engine. Moreover, the height H of the cap part 2a is set to the height located inside the rotation locus L of the crankshaft.

  The skirt portion 5a of the cylinder block 5 is a half skirt, and the side wall 3 of the ladder frame 1 is attached to the lower side of the half skirt portion 5a of the cylinder block 5 to constitute the lower portion of the skirt portion. The side wall 3 has a height approximately half that is lower than the height from the upper surface 2b of the bearing cap 2 to the lowermost end 2a ′ of the cap portion 2a. That is, the ladder frame 1 is formed by reducing the height of the side wall 3 that forms the lower part of the skirt portion 5 a of the cylinder block 5.

  The cap portion 2a is inclined from the both shoulder portions 2d obliquely upward and connected to the lower end of the side wall 3. The height of the lowermost end 2a ′ of the cap portion 2a and the height from the lowermost end 2a ′ to the shoulder 2d and the lower end of the side wall 3 are above (inside) the rotation locus of the crankshaft indicated by the two-dot chain line. positioned. As shown in FIG. 2, the side wall 3 has a shape in which a portion 3 b between the bearing caps 2 is bulged outwardly corresponding to the rotation locus of the crankshaft with respect to the portion 3 a connected to each bearing cap 2. It does not interfere with the rotating crankshaft.

  An attachment flange 3c is formed at the upper end of the side wall 3 and is formed at the lower end of the cylinder block 5 and is attached to the attachment flange 5b. An attachment flange 3d for attaching the attachment flange 6a of the oil pan 6 is formed at the lower end. ing. That is, the mounting flange 3d is provided such that the upper side wall 3 is reduced from the cap portion 2a, and the flange portion 6a of the oil pan 6 is positioned above the lowermost end 2a ′ of the cap portion 2a.

  And it connects with the lower end of the side wall 3 by the wall surface which goes diagonally upward from the lowest end 2a 'of the cap part 2a, More specifically, it connects with the lower end of the side wall 3 by the wall surface 2f which goes diagonally upward from the shoulder part 2d of the cap part 2a. Thereby, the area of each wall surface part (partition wall surface) 2g becomes small. Further, by positioning the oil pan mounting flange 3d above the lowermost end 2a ′ of the cap portion 2a, the area occupied by the side wall 3 (skirt portion) in the height direction is reduced. Thereby, the weight ratio of the partition part 2g and the side wall 3 which occupies the whole ladder frame 1 decreases, and the weight reduction of the ladder frame 1 is achieved.

  Further, the wall surface portion 2g of each bearing cap 2 is formed with a thin portion 2h in a continuous portion with the side wall 3, so that the weight can be reduced and the structure can be connected within the minimum necessary range. Thereby, the weight reduction of the ladder frame 1 is achieved without impairing the rigidity and function of the ladder frame structure that suppresses the vibration of the side wall 3 as the skirt portion. Further, the amount of material used for manufacturing the ladder frame is reduced, and the manufacturing cost can be reduced.

  Both shoulder portions 2d of the cap portion 2a are provided with main bolt holes 2h penetrating from the lower surface to the upper surface 2b. Sub-bolt holes 2i penetrate the side walls 3 on both sides of the bearing cap 2 of the mounting flanges 3c and 3d. Is provided. The main bolt hole 2h is a main bolt mounting hole for fastening the bearing cap 2 to the main cap of the cylinder block 5, and the sub bolt hole 2i is a sub bolt for fastening the ladder frame 1 to the cylinder block 5 to enhance the sealing performance. This is a mounting hole. The mounting flange 3d is provided with a number of bolt holes 3e for mounting the mounting flange 6a of the oil pan 6.

  The ladder frame 1 is disposed on the lower side of the cylinder block 5 so as to pivotally support a crankshaft journal (both not shown) by the main cap and the bearing cap 2 of the cylinder block 5. The mounting flange 3c is brought into contact with the flange 5b through a gasket and is fixed to the main cap with a main bolt.

  Further, the ladder frame 1 is fixed to the cylinder block 5 with a sub bolt in order to improve the sealing performance between the mounting flange 5b and the mounting flange 3c. Thereby, the ladder frame 1 is firmly fixed to the lower surface of the skirt portion 5a of the cylinder block 5, and the rigidity of the skirt portion 5a is improved. An oil pan 6 is disposed below the ladder frame 1, and the mounting flange 6a of the oil pan 6 is fixed to the mounting flange 3d with a bolt (not shown) via a gasket.

  The side wall 3 of the ladder frame 1 is reduced in height and positioned at a position higher than the lowermost end 2a ′ of the cap portion 2a, and the side bolt 3 is provided with a sub bolt hole 2i, thereby shortening the length of the sub bolt. Accordingly, the weight of the sub bolt can be reduced. Therefore, combined with the ability to reduce the weight of the ladder frame 1, it is possible to reduce the weight of the entire engine.

  FIG. 3 is a graph showing an example of the surface vibration of the cylinder block when the ladder frame structure of the present invention shown in FIG. 1 is applied and the surface vibration of the cylinder block when the conventional ladder frame structure is applied. The vibration characteristics when the ladder frame of the present invention is used are shown, and the thin line shows the vibration characteristics when the conventional ladder frame is used. As shown in this graph, the ladder frame structure of the present invention has substantially the same vibration level as the conventional ladder frame structure. Therefore, the ladder frame structure of the present invention can reduce the weight without impairing the vibration level of the cylinder block.

It is a front view of the ladder frame concerning the present invention. It is the perspective view seen from the slanting lower part of the ladder frame shown in FIG. It is a graph which shows an example of the crankcase surface vibration at the time of applying the ladder frame which concerns on this invention shown in FIG. 1, and the crankcase surface vibration at the time of applying the conventional type ladder frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ladder frame 2 Bearing cap 2a Cap part 2c Bearing surface 3 Side wall 3c, 3d Mounting flange 3f Wall surface 3g Wall surface (partition wall part)
5 Cylinder block 5a Skirt 5b Mounting flange 6 Oil pan 6a Mounting flange

Claims (2)

In a ladder frame structure in which both ends of a plurality of bearing caps fastened to the lower surface of the cylinder block are connected by side walls,
The height of the cap portion of the bearing cap is set to a height defined by at least the maximum load due to the maximum combustion pressure of the engine cylinder,
A ladder frame characterized in that the lower end of the side wall is provided above the lower end of the cap part, and the cap part and the lower end of the side wall are connected by a wall surface obliquely upward from the lower end of the cap part. Construction.   The ladder frame structure according to claim 1, wherein a through hole is provided in the side wall, and a bolt for fastening the ladder frame to the cylinder block is inserted into the through hole.

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