JPH0618013Y2 - Engine cylinder block structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an engine cylinder block structure, and more particularly to an engine cylinder block structure having improved crankshaft support rigidity.

(Prior Art) Conventionally, when oil is collected from an engine cylinder head or the like to an oil pan, for example, as disclosed in Japanese Utility Model Laid-Open No. 58-12616, one end of the cylinder block is opened to the cylinder head. It is known that an oil return passage whose end opens to the crank chamber is provided so that oil in the cylinder head or oil mist in blow-by gas is collected in an oil pan below the crank chamber via this oil return passage. .

(Problems to be Solved by the Invention) Generally, when a crankshaft is arranged in a cylinder block, a plurality of main bearing portions provided in a lower portion of the cylinder block and a main bearing cap attached to each main bearing portion are used. The journal portion of the crankshaft is rotatably supported.

However, it is necessary to increase the support rigidity of the crankshaft as much as possible in terms of suppressing engine vibration. Therefore, in addition to the cylinder block, a lower block that forms a crank chamber is provided below the cylinder block, and the main bearing caps are integrally formed on the lower block to improve the support rigidity of the crankshaft. It is possible.

However, in this case, since the outermost main bearing cap portion is integrally formed with the lower block, there is a problem in processing the oil that flows out from the lower block end wall side of the outermost main bearing cap portion, that is, the end flow oil.
As a measure for treating this end-flow oil, for example, it is possible to collect it in an oil pan via an oil return passage. However, when providing this oil return passage, the engine is made compact and the end of the return oil is It is necessary to effectively prevent backflow to the main bearing cap.

The present invention has been made in view of the above point, and an object of the present invention is to reduce the end flow oil of the end main bearing cap portion of the lower block while keeping the overall length of the engine compact. Between the lower part and the lower block end wall to the oil pan,
It is to prevent backflow while returning.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, the end flow oil of the outermost main bearing cap portion of the lower block is provided between the outermost main bearing cap portion and the lower block end wall. The passage for collecting the end flow oil in the provided space and returning the end flow oil to the oil pan is an offset passage in order to make the engine compact and prevent the reverse flow of oil.

Specifically, the solution provided by the present invention is to dispose a lower block in which a crank chamber is formed inward and each main bearing cap portion of a crankshaft is integrally formed below a cylinder block. An oil return space for collecting end flow oil of the outermost main bearing is formed between the outermost main bearing cap portion of the lower block and the lower block end wall. An offset in which one end is opened at the bottom of the oil return space and the other end is displaced inward of the lower block with respect to the oil return space, and is opened at the lower surface of the end main bearing cap portion at the lower part of the outermost main bearing portion. Forming a passage. Further, the lower surface of the lower block end wall below the oil return space is formed as an oil pan rail portion for mounting the oil pan flange portion.

(Operation) With the above configuration, in the present invention, the end flow oil of the outermost main bearing is collected in the oil pan below the lower block via the oil return space and the offset passage.

In that case, since the offset passage is displaced inward of the lower block with respect to the oil return space, it is difficult for scattered oil below the lower block and oil mist in blow-by gas to enter the oil return space, and backflow of oil is prevented. It

Also, by arranging the offset passage inside the lower block, it is not necessary to provide the lower surface of the lower block end wall as the oil pan rail portion to the outside, so the length of the oil pan does not become long, and the total length of the engine does not increase. It becomes compact.

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

1 to 5 show a cylinder block structure according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a cylinder block, the lower surface of the cylinder block 1 is open, and a plurality of cylinders are formed inside the upper part.
A lower block 2 is arranged below the cylinder block 1 and is fastened to the cylinder block 1 with bolts. The lower block 2 is formed into a housing whose upper and lower surfaces are open, and a crank chamber 3 is formed inside the lower portion of the cylinder block 1 and inside the lower block 2. An oil pan 4 is arranged below the lower block 2. A crankshaft 5 is arranged between the cylinder block 1 and the lower block 2.

That is, as shown in FIG.
A plurality of (two in the figure) partition walls 6 and 7 are integrally formed in front and rear so as to partition the crank chamber 3 between the cylinders. Semicircular main bearing portions 8 are formed on the lower ends of the partition walls 6 and 7 and on the inner sides of the lower ends of the front and rear end walls 1a and 1b of the cylinder block 1, respectively. On the other hand, as shown in FIGS. 3 to 5, the lower block 2 has a position corresponding to each main bearing portion 8, that is, a lower portion between cylinders and an inner side of the front and rear end walls 2a and 2b of the lower block 2. The four main bearing cap portions 9 are integrally formed with the lower block 2, respectively. The main bearing portions 8 of the cylinder block 1 and the main bearing cap portions 9 of the lower block 2 rotatably support the journal portions of the crankshaft 5, and the main bearing cap portions 9 are integrated with the lower block 2. By forming it, the support rigidity of the crankshaft 5 is improved.

Further, as shown in FIGS. 3 and 4, an oil return space 10 is formed between the rear end main bearing cap portion 9 of the lower block 2 and the lower block rear end wall 2b. The end flow oil of the bearing is collected.

Further, as shown in FIG. 4 and FIG. 5, at the lower center of the rear end main bearing cap portion 9 of the lower block 2, one end opens to the bottom of the oil return space 10 and the other end opens to the oil return space 10. On the other hand, an offset passage 11 is formed which is displaced inward of the lower block 2 and opens to the lower surface of the rearmost main bearing cap portion 9 so that the oil in the oil return space 10 is returned to the oil pan 4.

Further, as shown in FIGS. 3 and 4, the oil return space 10 is provided on the upper surface of the lower block 2 on the side of the rearmost main bearing cap portion 9 in the cylinder block 1.
The communication part 13 communicating with the blow-by gas passage 12 inside
It is provided so as to be displaced inward of the lower block 2 with respect to the oil return space 10. Therefore, the blow-by gas in the crank chamber 3 is guided to the blow-by gas passage 12 through the offset passage 11, the oil return space 10 and the communication portion 13, and is supplied from the blow-by gas passage 12 to the intake passage.

Furthermore, the oil pan 4 has an opening on its upper surface that is folded back to form a flange portion 4a. On the other hand, an oil pan rail portion 14 to which the flange portion 4a is attached is provided on the lower end surface of the lower block 2. Particularly, at the rear end of the lower block 2, the lower surface of the lower block rear end wall 2b below the oil return space 10 is the oil pan rail portion 1
4 is formed.

Therefore, in the above embodiment, the offset passage 1
Since 1 is displaced inward of the lower block 2 with respect to the oil return space 10, the scattered oil in the crank chamber 3 and the oil mist in the blow-by gas are obstructed by the wall surface between the offset passage 11 and the oil return space 10. As a result, it is difficult for the oil to return to the oil return space 10, and the reverse flow of oil is effectively prevented. Moreover, since the offset passage 11 is opened to the lower surface of the rearmost main bearing cap portion 9 below the crank chamber 3, the return oil simply returns to the oil pan 4 and is agitated by the rotation of the crankshaft 5 to generate oil mist. There is nothing to increase. Further, since the communication portion 13 to the blow-by gas passage 12 is displaced inward of the lower block 2 with respect to the oil return space 10,
It is possible to reliably prevent the oil mist from entering the blow-by gas passage 12.

Further, since the offset passage 11 is arranged inside the lower block 2 using the main bearing cap portion 9, the lower block rear end wall 2b as the oil pan rail portion 14 is provided.
Since the lower surface does not have to be provided outside, the length of the oil pan 4 does not become long, and the overall length of the engine becomes compact.

Further, in order to improve the support rigidity of the crankshaft 5, the lower block 2 is provided separately from the cylinder block 1,
Since the lower block 2 is provided with the oil return space 10, the offset passage 11 and the communicating portion 13, the processing can be simplified.

(Effect of the Invention) As described above, according to the cylinder block structure of the engine of the present invention, the end flow oil of the end main bearing cap portion of the lower block is transferred to the end main bearing cap portion and the lower block end wall. Since the oil return space provided between the oil return space and the oil return space is returned to the oil pan below the lower block through an offset passage formed by being displaced inward of the lower block with respect to the oil return space. By forming the lower surface of the lower block end wall on the oil pan rail part to make the oil pan length and the engine total length compact, it is possible to prevent the reverse flow of return oil and the increase of oil mist by the offset passage, and to process it. Can be simple.

[Brief description of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a front view of an engine, FIG. 2 is a bottom view of a cylinder block, FIG. 3 is a plan view of a lower block, FIG. 4 is a vertical side view of the same, and FIG. The figure is a bottom view of the same. 1 ... Cylinder block, 2 ... Lower block, 2a, 2b
... end wall, 3 ... crank chamber, 4 ... oil pan, 4a ... flange part, 5 ... crankshaft, 9 ... main bearing cap part, 10 ... oil return space, 11 ... offset passage, 14 ... oil pan rail part.

Claims (1)

[Scope of utility model registration request] 1. A lower block, in which a crank chamber is formed inwardly and main bearing cap portions of a crankshaft are integrally formed, is arranged below a cylinder block, and an outermost main bearing of the lower block is provided. An oil return space for collecting the end flow oil of the outermost main bearing is formed between the cap portion and the lower block end wall, and one end of the oil return space is formed at the bottom of the outermost main bearing cap portion. An offset passage is formed that opens at the other end and is shifted toward the inside of the lower block with respect to the oil return space and opens at the lower surface of the endmost main bearing cap portion
A cylinder block structure for an engine, wherein a lower surface of a lower block end wall below the oil return space is formed on an oil pan rail portion for mounting an oil pan flange portion.