JPH02188609A - Cylinder block of engine - Google Patents

Abstract

PURPOSE:To assure smooth flow of lubricating oil, etc., and to narrow the width of a cylinder block by providing a lubricating oil returning passage, etc., at a position for avoiding interference with each balancer shaft, specially with each counter weight part. CONSTITUTION:A pair of left and right balancer shafts 17 extend along a cylinder line direction at positions near by the inner wall 3 of a cylinder block at both sides of the first to the third cylinder bores 6a-6c. Each of the balancer shaft 17 is provided with a counter weight portion 18 eccentric to an axis and a shaft portion 19 extending from one end side thereof. In this case, two pairs of passages 10 are arranged at the side of the fourth cylinder bore 6d having no counterweight portion 18 and a pair of passages 10 are arranged at the side of the first cylinder bore 6a having the shaft portion 19. Namely, each passage 10 is arranged at the position for avoiding interference with the counterweight portion 18.

Description

Detailed Description of the Invention [Object of the Invention] <Industrial Application Field> The present invention particularly relates to a cylinder block for an engine that is provided with a balancer shaft on the side of a cylinder row for canceling secondary excitation force. .

<Prior art> In order to cancel the secondary excitation force generated in the 4-cycle in-line 4-cylinder engine, which is said to be the most popular type of reciprocating piston engine for vehicles, a balancer shaft having a counterweight part is cranked. A structure in which the shaft rotates together with the shaft is known (Japanese Patent Laid-Open No. 61-10
(See Publication No. 4114, etc.).

On the other hand, in order to return the lubricating oil that lubricates the valve gear installed in the cylinder head to the oil pan, or to alleviate pressure pulsations in the crankcase caused by the reciprocating movement of the piston, the cylinder head is For installation, the cylinder block is provided with a passage that communicates the end face with the inside of the crankcase. This passage is generally provided between adjacent cylinder bores or in a portion corresponding to the journal walls at both ends in the cylinder row direction.In particular, in the above publication, the passage passes through the space of the accommodation portion of the balancer shaft. A structure has been proposed in which this passage is formed at a location.

<Problems to be Solved by the Invention> By the way, if an attempt is made to provide an internal crankcase ventilation passage or a lubricating oil return passage in the journal wall, the cross-sectional area of the passage will be determined by the thickness of the journal wall. Particularly in engines with a balancer shaft as described above, it is customary to provide the bearing part of the balancer shaft on the journal wall, so it is necessary to ensure the cross-sectional area of the passage, support rigidity of the balancer shaft, and It is difficult to avoid interference between the bearing hole and the passage.

In particular, providing passages in the journal walls at both ends in the cylinder row direction is not preferable in terms of promoting compactness of the cylinder block, and the degree of freedom in design is further restricted. In addition, if a passage is opened in the balancer shaft storage part as proposed in the above publication, the counterweight part rotates at high speed, which may impede the smooth flow of blow-by gas or prevent the balancer shaft from flowing smoothly. It is conceivable that lubricating oil may adhere to the surface and cause rotational resistance.

The present invention has been made to solve the problems of the prior art, and its main purpose is to provide a ventilation passage or a lubricating oil return passage within the crankcase that does not interfere with the counterweight portion. The object of the present invention is to provide an improved engine cylinder block.

[Structure of the Invention] Means for Solving the Problems According to the present invention, such an object is to provide a cylinder row that is eccentric with respect to the center of rotation on the side of a cylinder row consisting of a plurality of cylinders arranged in series. A cylinder block for an engine is provided with a balancer shaft formed of a counterweight portion, in which a passage communicates between the cylinder head mounting surface side and the crankcase side in order to ventilate the crankcase or return lubricating oil. This is achieved by providing a cylinder block for an engine, which is provided at a position avoiding the counterweight portion in a portion sandwiched between adjacent journal walls on the sides of the cylinder. In particular, a bearing hole for supporting the balancer shaft may be provided in the journal wall, or the balancer shaft and the passage may be provided in a position close to the cylinder, and the cylinder relative to the center of the cylinder block in the cylinder row direction. a dimension to the center of the balancer shaft in a direction perpendicular to the row;
The dimensions up to the center of the passage are approximately equal, and the passage is provided at a position that avoids the counterweight portion in the axial direction of the balancer shaft, or the passage has a relatively large cross-sectional area. The first passage includes a first passage and a second passage having a relatively small cross-sectional area, the first passage is provided at a position where it does not interfere with the entire balancer shaft, and the first passage is provided at a position where it does not interfere with at least the counterweight portion of the balancer shaft. If a second passage is provided, or if the balancer shaft has a counterweight portion on the center side in the direction of the cylinder row in order to cancel the secondary excitation force of the 4-cycle in-line 4-cylinder engine, It is preferable that the passage be provided on the end side in the cylinder row direction.

<Function> In this way, the passage for ventilating the crankcase or returning the lubricating oil is located at a position that avoids the counterweight part in the part sandwiched between adjacent journal walls on the side of the cylinder. If provided, a sufficient cross-sectional area of the passage can be ensured, the balancer shaft does not obstruct the flow of the blow-by gas, and can avoid being subjected to rotational resistance due to the lubricating oil. In particular, if the bearing of the balancer shaft is provided on the journal wall, it is possible to achieve both support rigidity of the balancer shaft and freedom in setting the passage position. Further, by arranging the balancer shaft and the passage close to the cylinder and providing the passage at a position avoiding the counterweight portion in the axial direction, it is possible to contribute to downsizing of the cylinder block. Furthermore, most of the fluid can flow through the passages on the larger cross-sectional side without interfering with the balancer shaft.

<Embodiments> Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a plan view of a cylinder block 1 in an in-line four-cylinder engine constructed according to the present invention.

This cylinder block 1 is made of cast aluminum alloy, for example, and has a water jacket 4 formed between a cylinder block outer wall 2 and a cylinder block inner wall 3.
The piston (
Cylinder bores 6a to 6d are formed in which cylinders (not shown) slide.

The upper surface of the cylinder block 1 is ground smooth to form a cylinder head joint surface 7. Around the water jacket 4 on the cylinder head joint surface 7, at intermediate positions between the adjacent cylinder bores 6a to 6d and at both ends in the cylinder row direction, there are a total of 10 holes, in pairs at approximately equal intervals. A bolt hole 8 is bored along the cylinder axis. These bolt holes 8 are formed with internal threads for screwing head bolts for fastening a cylinder head (not shown).

The first cylinder bore 6a and the fourth cylinder bore 6 located at both ends in the cylinder row direction on the cylinder head joint surface 7
A passage 10 that communicates with the inside of the crankcase 9 (FIG. 3) opens at the side of d.

A pair of these passages 10 are opened on the side of the first cylinder bore 6a, and two pairs of passages are opened on the side of the fourth cylinder bore 6d, each opening at approximately symmetrical positions across the center line in the cylinder row direction. The side functions as an oil return passage for returning lubricating oil around the valve mechanism to the oil pan, and the other side serves as a ventilation passage in the crankcase for circulating blow-by gas between the cylinder head and crankcase. functions as In the case of this embodiment, the engine is mounted at an angle so that the passage located on the right side in FIG. 4 mainly serves as an oil return passage.

In addition, a lubricating oil discharge port is provided on the right side of the cylinder block outer wall 2 between the second and third cylinder bores 6b and 6C for supplying lubricating oil to a valve mechanism provided in the cylinder head (not shown). A channel 11 is drilled parallel to the bolt hole 8.

As shown in FIG. 2, both ends of the cylinder block 1 in the cylinder row direction and the adjacent cylinder bores 6a to 6
At the intermediate position of d, there is a journal part of the crankshaft (
Journal walls 13a to 13e having bearing portions 12 are formed to pivotally support the bearings (not shown). These journal walls 13a to 13e are formed along a plane that is parallel to the cylinder axis and perpendicular to the cylinder row direction, and each pair of journal walls 13a to 13e are provided on the lower surface thereof to fasten a bearing cap (not shown). Ten bolt holes 14 are drilled along the cylinder axis. Further, an oil pan flange 15 is formed outwardly on the lower surface of the cylinder block 1, which is ground to a flat surface for joining an oil pan (not shown), and a plurality of bolt holes 16 are drilled therein. .

On the other hand, as shown in FIGS. 3 and 4, a pair of left and right balancer shafts 17 are installed at positions relatively close to the cylinder block inner wall 3 on both sides of the first to third cylinder bores 6a to 6C. It extends in the direction. As clearly shown in FIG. 4, these balancer shafts 17 have a counterweight portion 18 provided at an eccentric position with respect to the axis.
and an extended shaft portion 19 extending from one end side of the counterweight portion 18. A first bearing portion 20a is provided on the free end side of the extension shaft portion 19, and a first bearing portion 20a is provided on the free end side of the extension shaft portion 19.
A second bearing portion 20b is formed at the other end, and a third bearing portion 20c is formed at the intermediate portion of the counterweight portion 18. Further, the counterweight portion 18 is connected to the second and third cylinder bores 6bφ6C in the central portion in the cylinder row direction.
The first bearing portion 20a is provided on the side of the first journal wall 13a on the first cylinder bore 6a side.
The second bearing part 20b is provided in the bearing hole 21a, the second bearing part 20b is provided in the second bearing hole 21b provided in the fourth journal wall 13d between the 3φ fourth cylinder bores 6C and 6c, and the third bearing part 20c is provided in the second and third cylinder bores 6b.・Third journal wall 13c between 6c
They are rotatably fitted into third bearing holes 21c provided in the respective third bearing holes 21c.

In this way, the balancer shaft 17 is supported by the cylinder block 1 with sufficiently high rigidity to prevent it from whirling.

The shaft ends of both balancer shafts 17 are connected to the first journal wall 1
Timing pulleys 22 are fixed to the ends of the shafts protruding from the shafts 3a, respectively.

By connecting the timing pulley 22 and the crankshaft via a toothed belt (not shown), both balancer shafts 17 are driven to rotate at twice the speed of the crankshaft and in opposite directions. In the case of this embodiment, of both balancer shafts 17, the one located on the left side in FIG. 4 rotates clockwise when viewed from the timing pulley 22 side, and the one located on the right side rotates counterclockwise. It is like that.

The second journal wall 13b between the 1φ second cylinder bores 6a and 6b has second and third bearing portions 20b and 20c.
A large-diameter hole 23 through which the
A tool insertion hole 24 for machining the bearing hole 21b is open. This tool insertion hole 24 is closed by attaching a transmission case (not shown).

As shown in FIG. 5, the second and third cylinder bores 6b and 6
Water jacket in c! - A skirt 25 extends from a portion adjacent to the bottom of 4 toward both sides. This skirt 25 extends in a direction generally perpendicular to the cylinder axis to partially surround the outer periphery of each balancer shaft 17, and then extends downward along a plane generally parallel to the cylinder axis, and then The oil pan flange 15 described above is formed therein.

As shown in FIGS. 3 and 6, the first journal wall 13
Skirt portions 25 on both sides of the cylinder are provided on both sides of the cylinder between A and the second journal wall 13b, and on both sides of the cylinder between the fifth journal wall 13e and the fourth journal wall 13d. By extending toward the head joint surface 7 side, cavities 26a and 26b of appropriate volume are defined. The passage 10 described above is located in this space 26.
They communicate with the inside of the crankcase 9 via a and 26b, respectively.

Now, in an engine equipped with the balancer shaft 17 as described above, if the position of the passage 10 that communicates the inside of the crankcase 9 and the cylinder head with each other interferes with the balancer shaft 17, the cross-sectional area of the passage is reduced by the counterweight part 18. In addition, if the lubricating oil flowing down from the cylinder head side into the crankcase 9 comes into direct contact with the counterweight part 18 rotating at high speed, the balancer shaft 17 will rotate. It is possible that there will be resistance.

Therefore, in the present invention, two pairs of passages 10 are provided on the sides of the fourth cylinder bore 6d where the counterweight portion 18 does not exist.
A pair of passages 10 are arranged on the sides of the first cylinder bore 6a where the extension shaft portion 19 is located. That is, interference with the counterweight portion 18 in the axial direction of the balancer shaft 17 is avoided, and the balancer shaft 1
A passage is provided at a position avoiding the bearing 7. By doing so, most of the fluid can flow through the portion of the balancer shaft 17 that is not affected, and the portion of the extended shaft portion 19 that is relatively unaffected can be used as an auxiliary passage. Therefore, smooth circulation of return lubricating oil or blow-by gas can be obtained, and sufficient passage capacity can be secured. Further, as shown in FIG. 3, a balancer shaft 17 is extended at a position relatively close to the cylinder block inner wall 3, and the distance dimension (A dimension) between the cylinder center and the balancer shaft center is
The distance dimension (8 dimensions) between the cylinder center and the passage center are approximately approximate values, thereby suppressing an increase in the width dimension of the cylinder block 1 as much as possible.

In addition, in the embodiment described in section 1, there are two pairs of passages 10 on the fourth cylinder bore 6d side, and the cross-sectional area thereof is relatively large, but this is made larger than that on the first cylinder bore 6a side. The configuration is not limited to the above configuration.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a lubricating oil return passage or a crankcase ventilation passage in a position of the balancer shaft that avoids interference with the balancer shaft, especially with the counterweight portion in the axial direction. This is highly effective in ensuring smooth flow of lubricating oil and blow-by gas and eliminating factors that cause rotational resistance of the balancer shaft. Moreover, since the increase in the widthwise dimension of the cylinder block is suppressed as described above, it is also effective in promoting downsizing of the engine with the balancer shaft.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a cylinder block constructed according to the present invention, and FIG. 2 is a bottom view. FIG. 3 is a cut end view taken along the line ■-■ in FIG. 1. FIG. 4 is a cut end view taken along the mV-mV line in FIG. 3. FIG. 5 is a cut end view taken along the line VV in FIG. 1, and FIG. 6 is a cut end view taken along the same <Vl-Vl line. 1... Cylinder block 2... Cylinder block outer wall 3... Cylinder block inner wall 4... Water jacket 5... Liner 6a to 6d... Cylinder bore 7... Cylinder head joint surface 8... Bolt hole 9...Crankcase 10
...Passage 11...Lubricating oil discharge path 12...
・Bearing parts 13a to 13e... Journal wall 14... Bolt hole 15... Oil pan flange 16... Bolt hole 17... Balancer shaft 18... Counterweight part 19... Extension shaft part 20a-20c... Bearing parts 21a-21c... Bearing hole 22... Timing pulley 23... Opening 24... Tool insertion hole 25.
・・Skirt part 26a・26b・・When vacant
Applicant: Honda Motor Co., Ltd. Representative
Person Patent Attorney Yo Oshima - Figure 2 Figure 3 Figure 5 X' Figure 6

Claims (5)

[Claims] (1) An engine cylinder block comprising a balancer shaft formed with a counterweight portion eccentric to the center of rotation formed on the side of a cylinder row consisting of a plurality of cylinders arranged in series, the crankshaft comprising: A passage communicating between the cylinder head mounting surface side and the crankcase side for ventilating the case or returning lubricating oil is located at the counterweight in a portion sandwiched between adjacent journal walls on the side of the cylinder. An engine cylinder block characterized in that it is installed in a position that avoids the central part of the engine. (2) The engine cylinder block according to claim 1, wherein a bearing hole for supporting the balancer shaft is provided in the journal wall. (3) The balancer shaft and the passage are provided in a position close to the cylinder, and the dimension from the center of the cylinder block in the cylinder row direction to the center of the balancer shaft in a direction perpendicular to the cylinder row, and the passage The engine according to claim 1 or 2, wherein dimensions up to a center portion are substantially equal, and the passage is provided at a position avoiding the counterweight portion in the axial direction of the balancer shaft. cylinder block. (4) The passage includes a first passage having a relatively large cross-sectional area and a second passage having a relatively small cross-sectional area, and the first passage is provided at a position that does not interfere with the entire balancer shaft, and the balancer shaft The cylinder block for an engine according to claim 3, wherein the second passage is provided at least at a position of the shaft that does not interfere with the counterweight portion. (5) The counterweight portion of the balancer shaft is formed on the center side in the cylinder row direction in order to cancel the secondary excitation force of the 4-cycle in-line 4-cylinder engine, and the passage is
The cylinder block for an engine according to any one of claims 1 to 4, characterized in that it is provided on an end side in a cylinder row direction.