JPH0364656A - Bearing structure for cylinder body - Google Patents

Abstract

PURPOSE:To reduce the generation of vibration and noise by a method wherein a rudder frame having a bearing surface for a crank journal is mounted on the under surface of a cylinder body, and a reinforcing plate formed of a metallic material having high rigidity is mounted on the under surface of the rudder frame. CONSTITUTION:A cylinder body 1 has a semicircular bearing surface 4 formed in the lower part of a partition wall 3 by which adjoining cylinders 2 are partitioned from each other. In this case, a rudder frame 6 is mounted in a horizontal under surface 5 of a cylinder body 1. The rudder frame 6 is formed with a plurality of side members 7 placed along the longitudinal direction of the cylinder body 1 and a plurality of cross members 8 intercoupled in the direction of the width of the cylinder body 1. A semicircular bearing surface 10 is formed in the side of the partition wall 3 of the cross member 8. Mean while, a reinforcing plate 14 formed of a metallic material having high rigidity is mounted on the under surface of the rudder frame 6, i.e. oil pan sides 13 of the side member 7 and the cross member 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bearing structure for a cylinder body that rotatably supports a crank journal.

[Conventional technology] Conventional aluminum cylinder bodies have been designed to increase the rigidity around the crank journal as a countermeasure against vibration and noise, and to reduce changes in clearance due to temperature changes due to aluminum's high coefficient of thermal expansion. The bearing cap is made of cast iron, and the structure is such that the bearing cap is bolted to the cylinder body.

That is, as shown in FIG. 4, a bearing surface d that engages the upper half of the crank journal C is formed on the partition wall of the aluminum cylinder body a, and the crank journal (crank bearing) is formed in the partition gb. Attach a bearing cap e that engages with the lower half of the bearing cap e, and install two bolts f on both sides of the bearing cap e that engage with the partition wall, and use the axial force of the four bolts f to tighten the bearing cap e. Proposal for firmly fixing it to the partition UB ("Internal combustion engine bearing cap installation structure")
JP-A-59-119047, etc.) were developed. However, even if the rigidity of the bearing cap e itself and the mounting strength of the bearing cap e are increased, the rigidity of the partition wall around the bearing cab 10 is low, and
When machining the internal diameter around the crank journal, machining time and accuracy are a problem because the materials used for the partition wall and the bearing cap are different.Therefore, in recent years, side members and cross members have been used to form a ladder frame on which the cylinder body is placed. However, a proposal has been made in which a bearing surface for rotationally supporting the crank journal is formed on the cross member to improve overall rigidity.

[Problems to be Solved by the Invention] However, as shown in FIGS. 5 and 6, when the ladder frame g is made of aluminum, the clearance of the bearing surface i with respect to the crank journal C is reduced due to thermal expansion and contraction of the cross member h. changes, and this change causes problems such as eccentric rotation of the crank journal C and an increase in rotational resistance of the crank journal C.

An object of this invention is to make the clearance between the bearing surface of the ladder frame and the crank journal constant.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a ladder frame having a bearing surface for rotationally supporting a crank journal, and a ladder frame formed from a metal material with higher rigidity and joined to the lower surface of the frame. The reinforcing plate is bolted to the cylinder body, and the frame and reinforcing plate located at the center of the bearing surface are bolted to the cylinder body.

[Operation] When heat from the crank journal and cylinder body is conducted to the ladder frame, the ladder frame expands and contracts depending on the degree of the heat.

However, since the reinforcing plate joined to the lower surface of the ladder frame, that is, the surface on the oil pan side, is formed of a metal material that is more rigid than the ladder frame, it forcibly prevents thermal expansion of the ladder frame.

If the frame and the reinforcing plate at the center of the bearing are fixed with bolts, even if the ladder frame attempts to contract, the reinforcing plate will prevent the ladder frame from shrinking. As a result, the clearance between the crank journal and the bearing surface can be set to an appropriate minimum clearance.

[Embodiment] A preferred embodiment of the present invention will be described below based on the accompanying drawings.

FIG. 1 shows a schematic cross-section of a cylinder body of a V-shaped multi-cylinder engine formed with a constant bank angle.

As shown in the figure, a partition wall 3 for partitioning adjacent cylinders 2 is integrally formed in the cylinder body 1, and a semicircular bearing surface that is engaged with the upper half of the crank journal is provided at the bottom of the partition wall. 4 is formed. The lower surface of the cylinder body 1, that is, the side surface of the oil pan, is formed as a horizontal surface continuous with both ends of the bearing surface 4, and an aluminum ladder frame 6 is attached to the horizontal lower surface 5 of the cylinder body 1. The ladder frame 6 moves the cylinder body l along the longitudinal direction of the cylinder body 1 (in the row direction of the cylinders 2)! and a plurality of cross members 8 for connecting the side members 7.7 to each other in the middle direction of the cylinder body 1 and for resting the space u3 by coming into contact with the space u3. be done. A semicircular bearing surface 10 that engages with the lower half of the crank journal 9 is formed on the side surface of the partition wall 3 of the cross member 8 . That is, this bearing surface 10 cooperates with the bearing surface 4 of the partition wall 3 to constitute a bearing portion for rotatably supporting the crank journal 9, and the side member 7 and the cross member 8 constitute a crank that accommodates the crank journal 9. form part of the game. Bolt insertion holes 11 are formed in the cross member 8 at predetermined intervals radially outward on both sides of the bearing surface 10 of the cross member 8 in the radial direction. Screw holes 12 are formed at positions corresponding to the bolt insertion holes 11.

Now, the purpose of this invention is the ladder frame 6
Bearing surface 10 of ladder frame 6 due to thermal expansion and contraction of
The purpose is to suppress thermal expansion and thermal contraction of the crank journal 9 and to keep the clearance to the crank journal 9 constant to suppress eccentric rotation of the crank journal 9 and an increase in rotational resistance.

Therefore, in this actual example, the above Raghu frame 6
The reinforcing plate 14 is integrally attached to the lower surface of the oil pan side surface 13 of the side member 7 and the cross member 8. The reinforcing plate 14 is attached to the ladder frame 6.
A metal material that has higher rigidity than the metal materials that make up the
For example, it is made of iron, cast metal, etc.

Bolt holes 15 are formed in the reinforcing plate 14 at positions corresponding to the screw holes 12 of the partition wall 3, and another bolt hole 16 is formed in the middle of the bolt holes 15 and 15 located radially inward. configured. A screw hole 17 is formed on the lower surface of the cross member 8 in correspondence with the other bolt hole 16.

Therefore, the bolt 18 inserted into the bolt carpenter 5 of the reinforcing platework 4 is inserted into the bolt insertion hole 11 of the cross member 8, screwed into the screw hole 12 of the partition wall 3, and inserted into the other bolt hole 16. When another bolt 19 is screwed into the screw hole 17 of the cross member 8, the reinforcing plate 1 is attached to the partition wall 3.
4 are integrated, and the cross member 8 and the reinforcing plate 14 are also integrated by another bolt 19.

By the way, the bearing surface 1
Since the portion where 0 is formed has a smaller height than other portions, in this embodiment, the bolt hole 1
The height (thickness) of the reinforcing plate 14 between 8.18 and 18 is made larger than other parts to further increase rigidity.

Next, the action will be explained.

When heat from the crank journal 9 and cylinder body 1 is conducted to the cross member 8, the cross member 8 expands and contracts depending on the degree of the heat. However, the reinforcing plate 14 that is joined to the oil pan surface of the cross member 8 is made of a metal material that is more rigid than the cross member 8.
Moreover, since the portion having the bearing surface 10 is formed thicker than the other portions, thermal expansion of the cross member 8 is forcibly prevented. Then, the bearing surface 10
When the cross member 8 and the reinforcing plate 14 located at the center of the cross member 8 are fixed with bolts, the reinforcing plate 14 prevents the cross member 8 from shrinking due to heat.

In other words, when considering expansion and contraction in the case of a ladder frame structure without the reinforcing member 14, where Do is the inner diameter of the bearing at room temperature, t is the temperature difference from room temperature, and α is the linear expansion I51 coefficient,
When the temperature is high, the bearing expands as shown by the dotted line in Figure 5, resulting in D/2=D,/2 (1+αt).

Also, as shown in Figure 6, at low temperatures, the opposite is true: D/2=D
, /2 (1-αt).

On the other hand, when the reinforcing plate 14 is provided, the height of the cross member 8 is H, HD-D, /2=A.

When β is the coefficient of linear expansion, D/2=HO(1+βt)-A, (1+αt) at high temperatures, as shown by the dotted line in Figure 2.
This formula becomes D/2=Da/2+Hoβt−A, αt.

Then, if we select the material and set the dimensions to α yo 2βIH (1≧2A), Hoβt→A0αt, and the result is D
/2L5Do becomes /2.

At a low temperature, as shown in FIG. 3, D/2=D6/2-H, βt 0A oαt, and the equation becomes D/2ζD0/2.

In this way, in thermal expansion and contraction, α direction 2βH6≧2A
By selecting materials and setting dimensions, changes in the bearing clearance will no longer occur.

Therefore, the clearance between the crank journal 9 and the bearing surface 4.10 can be set to an appropriate minimum clearance, and the crank journal 9 can rotate properly. By being able to properly maintain the clearance, it becomes possible to secure high-temperature oil pressure to the bearing surface 4.10 and reduce low-temperature friction.

In the embodiment, the cylinder body 1 was explained as a cylinder body 1 for a V-type engine, but the above-mentioned configuration is naturally applicable to the cylinder body of a row-type engine as well. be. Further, the material of the reinforcing member 14 is, of course, made of a metal material having rigidity, but it is also a matter of course that it is made of a metal material having a lower coefficient of thermal expansion than that of the ladder frame 6.

[Effects of the Invention] As is clear from the above explanation, the present invention exhibits the following excellent effects.

A ladder frame having a bearing surface for rotationally supporting the crank journal and a reinforcing plate made of a metal material with higher rigidity and joined to the lower surface of the frame are bolted to the cylinder body, and the ladder frame is bolted to the cylinder body. Since the frame and reinforcing plate are bolted together, the rigidity of the ladder frame against thermal expansion and contraction is increased.

As a result, the clearance between the bearing and the crank journal becomes constant, suppressing vibration propagation to the cylinder body and reducing noise.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a preferred embodiment of the present invention, FIGS. 2 and 3 are explanatory views showing changes in the clearance of the bearing surface, and FIG. 4 is a partial sectional view showing a conventional example. FIGS. 5 and 6 are explanatory views showing changes in clearance in response to thermal expansion and contraction of a bearing surface in a conventional lug frame structure. In the figure, 1 is a cylinder body, 6 is a ladder frame, 4 is a bearing surface, 9 is a crank journal, and 14 is a reinforcing plate.

Claims (1)

[Claims] 1. A ladder frame with a bearing surface that rotationally supports the crank journal and a reinforcing plate made of a metal material with higher rigidity and joined to the lower surface of the frame are bolted to the cylinder body, and the center of the bearing surface is bolted to the cylinder body. A cylinder body bearing structure characterized in that the above-mentioned frame and reinforcing plate are bolted together.