JP2521666Y2 - Engine block structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to the structure of an engine cylinder block.

(Prior Art) As a structure for reinforcing a cylinder block of an engine, for example, as disclosed in Japanese Utility Model Laid-Open No. 62-61960, a skirt portion of a cylinder block of an engine is divided into upper and lower parts, and the divided skirt is formed. A bearing cap is integrally formed on a part of the part to reinforce the skirt part,
There is known an engine that reduces vibration noise of an engine. Further, as disclosed in Japanese Patent Laid-Open No. 63-71554, a main body plate that is formed so as to spread over the entire lower end opening of the skirt portion of the cylinder block and is convex downward, and a position substantially directly below the bearing portion for the crankshaft. At the lower end of the skirt portion of the cylinder block, and a weight ratio of the reinforcing member to the cylinder block is 1% to 1%. It is known that the range is set to 6% to effectively reinforce the cylinder block while suppressing the increase in weight and reduce the vibration noise of the engine.

(Problems to be solved by the invention) By the way, in the cylinder block having the lower block integrally provided with the skirt portion and the bearing cap portion, as in the one described in Japanese Utility Model Laid-Open No. 62-61960, further As a method of increasing the rigidity of the entire cylinder block, it is conceivable to connect the skirt portion and the bearing cap portion so that the lower block has a box-shaped structure with its lower portion closed. That is, an arc-shaped rib extending from the skirt portion and connecting the bearing cap portions is provided to prevent vibration such as deflection of the bearing cap portion due to combustion excitation force, and to improve rigidity of the entire cylinder block against bending and twisting. I tried to improve it,
Thereby, the vibration noise of the engine can be further reduced. However, due to the demand for engine compactness, the ribs are provided in an arc shape so as to escape the rotation loci of the crankshaft web and the connecting rod and to suppress the gap as much as possible. Tries to return to the oil pan,
On the rib, the rotation of the crankshaft impedes the return of the crankshaft, which deteriorates the oil return property.

The present invention has been made by paying attention to such a point, and an object of the present invention is to provide a cylinder block having a lower block in which a skirt portion of the cylinder block and a bearing cap portion are integrally provided. It is intended to further improve the rigidity of the entire cylinder block to obtain a high degree of quietness and to improve the oil return property.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a lower block integrally provided with a skirt portion and a bearing cap portion extends from the skirt portion to connect the bearing cap portions to each other. An arc-shaped rib is provided, and an oil return hole is provided on the crank shaft rotation scraping side of this rib.

Specifically, a solution provided by the present invention is an engine including a lower block integrally provided with a skirt portion forming a skirt of a cylinder block and a bearing cap portion forming a bearing cap of a crankshaft. Assumption. An arcuate rib extending from the skirt and connecting between the bearing caps is provided on the lower block so as to escape the rotational trajectory of the crankshaft web and the connecting rod. A return oil return port is provided so as to extend through a portion between the bearing caps on the rotation scraping side where the fresh air introduction passage for blow-by gas ventilation is not located.

(Operation) With the above configuration, in the present invention, since the bearing cap portions of the crankshaft are connected by the arcuate ribs in the lower block, vibration such as runout of the bearing cap portion due to combustion excitation force is suppressed. Along with
The arc-shaped ribs form a box-shaped structure in which the lower part is entirely closed by the skirt part and the bearing cap part. Therefore, the rigidity of the lower block against bending and twisting is improved, and accordingly the lower part is the lower block. The rigidity of the entire configured cylinder block against bending and torsion is further improved.

In addition, the oil that fell after cooling the piston etc.
By the scraping action of the rotation of the crank shaft, the arc-shaped rib smoothly returns to the oil pan through the return port penetrating to the scraping side of the crank shaft, and the oil return property is improved. Further, since the return port is provided at a portion where the fresh air introduction passage for blow-by gas ventilation is not located,
When the crankcase internal pressure rises due to an increase in blow-by gas amount during full-open operation etc., oil is prevented from flowing backward from the return port to the fresh air introduction passage and blocking this passage, ensuring the blow-by gas return function in the crankcase. To be done.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cylinder block of a V-type engine having an engine block structure according to an embodiment of the present invention. In the figure, reference numeral 1 is a cylinder block of a V-type 6-cylinder engine, which is divided into an upper block 2 constituting an upper part and a lower block 3 constituting a lower part. Three cylinders 4 are formed in each of the left and right banks of the upper block 2, and an upper skirt 5 is formed by an outer wall continuously extending from the lower portion of the cylinder 4. Further, the upper block 2 is provided with four bulkhead portions 6 which connect the left and right inner walls of the upper skirt 5 and the lower end portions of the cylinders 4 of the left and right banks to partition the inside of the crankcase and have a bearing portion for the crankshaft. Has been formed. In addition, the lower block 3
Has an upper surface joined to the lower surface of the upper block 2 and bolted to the upper block 2, and an outer wall of the upper block 2 is continuous with the upper skirt 5 to form a lower skirt 7. A bearing cap portion 8 of the crankshaft is continuously provided on the inner wall of the lower skirt 7 so as to correspond to the bulkhead portion.

As shown in FIGS. 2 to 4, the lower block 3 extends from the inner wall of the lower skirt 7 and connects between the bearing cap portions 8, 9, 10 and 11, respectively, and connects the crankshaft web and Rotating locus of connecting rod 14
Circular ribs 20 and 21 are provided on the left and right sides below the outer peripheral side of the rotation locus 14 so as to escape. The ends of the arc-shaped ribs 20 and 21 have a triangular cross-section with the beam portion 2
0a and 21a are formed to connect the lower end portions of the bearing cap portions.

Further, as shown in FIG. 2, the lower block 3 is a cylinder disposed on each upper surface of the left and right banks of the upper block 2 through the inside of the upper block 2 along the outer walls of the lower skirts 7 on the left and right sides. A blow-by gas passage 12 communicating with a head (not shown) is provided. The blow-by gas passage 12 also functions as an oil return passage for returning the oil, which has finished lubricating the valve operating system member arranged on the cylinder head, to the oil pan below the cylinder block, and the blow-by gas and the return oil. It is a common passage for

Further, in FIG. 3, in the engine of this embodiment, the crankshaft (not shown) rotates counterclockwise, and the left side of the lower block 3 is the crankshaft rotation scraping side. Then, along the outer wall of the lower skirt 7 on the left side, which is the side on which the crankshaft is rotated down, approximately at the center in the longitudinal direction of the cylinder block, as in the blow-by gas passage 12, inside the upper block 2 and the upper part of the cylinder head. A fresh air introduction passage 13 for ventilation of blow-by gas in the crankcase, which communicates with the intake passage, is provided.

Further, in the vicinity of the root portion of the arcuate rib 20 on the crank shaft rotation lowering side with the lower skirt 7, the fresh air introduction passage 13 is not located.
8 to 9 and 9 to 10, a return oil return port 20b is provided so as to communicate the lower oil pan side and the upper cylinder side.

With the above configuration, in the lower block 3, the bearing cap portions 8, 9, 10, 11 are connected to each other by the arcuate ribs 20, 21, and the lower end portions are more firmly connected by the beam portions 20a, 21a. Vibration of the bearing cap portion due to combustion excitation force is effectively suppressed, and the arcuate ribs 20 and 21 strengthen the connection between the lower skirt 7 and the bearing cap portions 8, 9, 10 and 11. Since it acts so as to form a closed box-shaped structure, the rigidity of the lower block 3 against bending and twisting is improved,
Along with this, the rigidity of the entire cylinder block 1 whose lower portion is composed of the lower block 3 against bending and twisting is improved.

Also, the oil that has dropped from the upper cylinder side after cooling the piston etc. is guided by the crank lowering action to the return oil return port 20b provided on the crankshaft rotation lowering side, and the lower oil passes therethrough. It smoothly returns to the pan side, improving the oil returnability.

At this time, since the return port 20b is not located in the portion where the fresh air introduction passage 13 for blow-by gas ventilation is located, when the blow-by gas amount increases and the crankcase internal pressure rises during full-open operation, the oil returns to the above-mentioned return state. The flow of fresh air for blow-by gas ventilation is not obstructed without backflowing from the port 20b to the fresh air introduction passage 13 to block the passage, and the blow-by gas reducing function is ensured.

Therefore, in the above-described embodiment, the rigidity of the entire cylinder block 1 is increased by the arcuate ribs 20 and 21 that connect the lower skirt 7 provided on the lower block 3 and the bearing cap portion, and the crankshaft rotation scraping side is improved. Return port for return oil provided on the arcuate rib 20
The oil return property is improved by 20b, and the return port 20b is not provided at the portion where the fresh air introduction passage 13 is located to ensure the blow-by gas reducing function.

(Effect of the Invention) As described above, according to the block structure of the engine of the present invention, the lower block is connected to the skirt portion and the bearing cap portion so that the lower block has a box-shaped structure. By providing the rib, the rigidity of the lower block can be improved, and accordingly, the rigidity of the entire cylinder block can be improved, and a return oil return port is provided on the crankshaft rotation scraping side of the arc-shaped rib. As a result, the oil return property can be improved, and the blow-by gas reducing function can be secured by providing the return oil return port at a position where the fresh air introduction passage is not located.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a cylinder block, FIG. 2 is a plan view of a lower block, and FIG.
Fig. 4 is a sectional view taken along the line III-III in Fig. 2, and Fig. 4 is IV- in Fig. 2.
FIG. 4 is a sectional view taken along line IV. 1 ... Cylinder block 2 ... Upper block 3 ... Lower block 7 ... Lower skirt 8,9,10,11 ... Bearing cap 13 ... Fresh air introduction passage 20, 21 ... Arc-shaped rib 20b ... Return port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoshi Shiraishi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) References -34416 (JP, U) Actual flat 1-113116 (JP, U) Actual flat 3-30510 (JP, U)

Claims (1)

(57) [Scope of utility model registration request] 1. An engine comprising a lower block integrally provided with a skirt portion forming a skirt of a cylinder block and a bearing cap portion forming a bearing cap of a crankshaft, wherein the lower block has a skirt. Arc-shaped ribs extending from the portion and connecting between the bearing cap portions are provided so as to escape the rotation trajectory of the crankshaft web and the connecting rod, and between the bearing cap portions on the crankshaft rotation scraping side of the arc-shaped ribs. The engine block structure is characterized in that a return oil return port is provided in a portion where a fresh air introduction passage for blow-by gas ventilation is not located.