JP2556374B2 - Engine cylinder block - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a cylinder block of an engine, and more particularly to a balancer shaft for canceling secondary vibration force in a 4-cycle 4-cylinder engine. The present invention relates to a cylinder block of an engine, which is provided on the side of the cylinder row and has a ventilation passage in the crankcase that communicates between the cylinder head mounting surface side and the crankcase side.

<Prior Art> In order to cancel the secondary vibration force generated in a 4-cycle in-line 4-cylinder engine, which is said to be the most popular reciprocating piston engine for a vehicle, a balancer shaft having a counterweight part is used as a crank. A structure is known in which the shaft is rotated together with the shaft (Japanese Patent Laid-Open No. 61-1041).
(See No. 14, etc.)

On the other hand, in order to mitigate the pressure pulsation in the crankcase due to the reciprocating movement of the piston, the cylinder block is provided with a passage communicating between the mounting end surface of the cylinder head and the inside of the crankcase. This passage is generally provided between the cylinder bores adjacent to each other, or at both ends in the cylinder row direction corresponding to the journal wall. In particular, in the above publication, the space of the accommodating portion of the balancer shaft is defined. A structure has been proposed in which this passage is formed at a passing position.

<Problems to be Solved by the Invention> However, as disclosed in the above publication, if the crankcase ventilation passage is opened toward the accommodating portion of the balancer shaft, the counterweight portion provided eccentrically is provided. Is rotated at a high speed, which may hinder the smooth flow of blow-by gas.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and its main purpose is to provide an engine improved so that the ventilation passage in the crankcase and the balancer shaft do not interfere with each other. To provide a cylinder block.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, such an object is extended in the cylinder row direction to the side of a cylinder row composed of a plurality of cylinders arranged in series. A cylinder block of an engine having a balancer shaft and a ventilation passage in the crankcase extending along the axis of the cylinder, wherein the ventilation passage in the crankcase is the farthest from the connection portion of the balancer shaft with the crankshaft. Is extended in a direction that intersects the axis of the balancer shaft at a position avoiding the balancer shaft on the side of, and the space for housing the balancer shaft and the space for opening the ventilation passage in the crankcase are separated by the journal wall, The portion of the skirt of the cylinder block that is adjacent to the opening of the ventilation passage in the crankcase is Are bulged toward the outer peripheral side of the emission coupling flange is achieved by providing a cylinder block of the engine, characterized in that it is connected to the transmission coupling flange.

<Operation> In this way, since the passage for ventilation in the crankcase and the balancer shaft do not interfere with each other,
It does not obstruct the smooth flow of blow-by gas. Also,
If this passage is provided on an extension of the axis of the balancer shaft, it is not necessary to increase the widthwise dimension of the cylinder block. In particular, if the space for accommodating the balancer shaft and the space for opening this passage are isolated by the journal wall, it is possible to more reliably prevent the rotation of the balancer shaft and the flow of the blow-by gas from affecting each other. . In addition, by expanding the skirt of the cylinder block toward the outer peripheral side of the transmission coupling flange and connecting it to the transmission coupling flange, the volume of the chamber in which blow-by gas flows is increased, so the oil separation effect is improved. At the same time, the rigidity of the transmission coupling flange can be increased.

<Embodiment> A preferred embodiment 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. The cylinder block 1 is made by casting, for example, an aluminum alloy, a water jacket 4 is formed between a cylinder block outer wall 2 and a cylinder block inner wall 3, and a cylinder block inner wall 3 located inside the water jacket 4 is formed. The casted liner 5 forms cylinder bores 6a to 6d on which a piston (not shown) slides.

The upper surface of the cylinder block 1 is ground smoothly to form a cylinder head joint surface 7. Around the water jacket 4 on the cylinder head joint surface 7, an intermediate position between the cylinder bores 6a to 6d adjacent to each other and both ends in the cylinder row direction at a substantially equal interval, one pair each, for a total of 10 pieces. Bolt holes 8 are formed along the cylinder axis. Inner threads are formed in these bolt holes 8 for screwing head bolts for fastening a cylinder head (not shown).

Fourth cylinder bore 6d on the cylinder head joint surface 7
Two pairs of passages 10 communicating with the inside of the crankcase 9 (Fig. 3) are open on both sides of the. These passages 10 open in substantially symmetrical positions across the center line in the cylinder row direction, and one side functions as an oil return passage for returning the lubricating oil lubricated around the valve mechanism to the oil pan. The other side functions as a ventilation passage in the crankcase for allowing blow-by gas to flow between the cylinder head and the crankcase. In the case of this embodiment, the engine is mounted so as to be inclined so that the passage located on the left side in FIG. 1 becomes the main blow-by gas passage (see FIG. 7).

The second and third cylinder bores 6b of the cylinder block outer wall 2
A lubricating oil discharge passage 11 for supplying lubricating oil to a valve operating mechanism provided in a cylinder head (not shown) is provided in parallel with the bolt hole 8 on the right side portion between 6c. There is.

As shown in FIG. 2, both ends of the cylinder block 1 in the cylinder row direction and adjacent cylinder bores 6a to 6d are adjacent to each other.
A journal wall having a bearing portion 12 for pivotally supporting a crankshaft journal portion (not shown) in an intermediate position of
13a to 13e are formed. These journal walls 13a-1
3e is formed along a surface parallel to the cylinder axis and orthogonal to the cylinder row direction. On the lower surface thereof, a pair of a pair of bearing caps (not shown) are fastened.
Ten bolt holes 14 are bored along the cylinder axis. An oil pan flange 15 is formed outward and a plurality of bolt holes 16 are formed on the lower surface of the cylinder block 1 that is ground to join an oil pan (not shown). .

On the other hand, at positions relatively close to the cylinder block inner wall 3 on both sides of the first to third cylinder bores 6a to 6c,
As shown in FIG. 3 to FIG. 5, the pair of left and right balancer shafts 17 are located at substantially symmetrical positions with the center line in the cylinder row direction interposed therebetween.
Are extended in the cylinder row direction. As shown in FIG. 4, the balancer shaft 17 includes a counter weight portion 18 provided at an eccentric position with respect to an axis and an extension shaft portion 19 extending from one end side of the counter weight portion 18. Has become. A first bearing portion 20a is formed on the free end side of the extension shaft portion 19, and a second bearing portion 20c is formed on the intermediate portion of the counterweight portion 18. Further, the counter weight part 18 is provided with the second and third parts in the central part in the cylinder row direction.
The first bearing portion 20a is provided on the side of the cylinder bores 6b and 6c.
However, in the first bearing hole 21a provided in the first journal wall 13a on the side of the first cylinder bore 6a, the second bearing portion 20c has the second and third bearing portions 20c.
It is rotatably fitted in the second bearing holes 21c provided in the third journal wall 13c between the cylinder bores 6b and 6c. In this way, the balancer shaft 17 is supported by the cylinder block 1 with sufficiently high rigidity so that whirling does not occur.

4th and 5th, where blow-by gas and return lubricating oil flow
Space between journal walls 13d and 13e and balancer shaft 17
The space between the first to fourth journal walls 13a to 13d in which the space is stored is isolated from each other by the fourth journal wall 13d itself.

The shaft ends of both balancer shafts 17 are attached to the first journal wall 13
Although protruding from a, the timing pulley 22 is fixed to each of the shaft ends. As shown in FIG.
By connecting the timing pulley 22 and the crank pulley 32 fixed to the crankshaft 31 via the timing belt 33, both balancer shafts 17 rotate in opposite directions at a rotation speed twice that of the crankshaft 31. It is driven to rotate. In the case of this embodiment, both balancer shafts 17
Among them, the one located on the left side in FIG. 7 rotates clockwise when viewed from the timing pulley 22 side, and the one located on the right side rotates counterclockwise.
A predetermined tension is applied to the timing belt 33 by a tension pulley 34 provided on the end surface of the cylinder block.

The second journal wall 13b between the first and second cylinder bores 6a and 6b is provided with a large-diameter hole 23 through which both the second and third bearing portions 20b and 20c can pass.

As shown in FIG. 5, second and third cylinder bores 6b and 6c
A skirt 25 extends from the portion adjacent to the bottom portion of the water jacket 4 in both directions toward both sides. The skirt 25 extends in a direction substantially orthogonal to the cylinder axis and partially surrounds the outer circumference of each balancer shaft 17, and then extends downward along a plane substantially parallel to the cylinder axis, and the end thereof. The oil pan flange 15 described above is formed.

As shown in FIG. 6, on both sides of the cylinder between the fifth journal wall 13e and the fourth journal wall 13d,
By extending the skirt portions 25 on both sides to the cylinder head joint surface 7 side, an empty space 26 having an appropriate volume is defined. The passage 10 is opened to the inner surface of the space 26 and passes through the crankcase 9.

Now, in the engine provided with the balancer shaft 17 as described above, the position of the passage 10 communicating between the crankcase 9 and the cylinder head is the balancer shaft.
When it interferes with the counterweight section 18, the counterweight section 18 narrows the cross-sectional area of the passage to hinder the smooth flow of blow-by gas, and the lubricating oil flowing down from the cylinder head side into the crankcase 9 rotates at a high speed.
It is considered that if it comes into direct contact with, it may cause rotation resistance of the balancer shaft 17.

Therefore, in the present invention, two pairs of passages 10 are provided on both sides of the fourth cylinder bore 6d where the balancer shaft 17 does not exist. That is, the passage is provided at a position where interference with the balancer shaft 17 in the axial direction thereof is avoided and the bearing of the balancer shaft 17 is avoided. By doing so, the fluid can be circulated in a portion that is not affected by the balancer shaft 17. Therefore, it becomes possible to obtain a smooth flow of the blow-by gas and to secure a sufficient passage capacity. Moreover, the increase in the width dimension of the cylinder block 1 can be suppressed as much as possible.

As shown in FIG. 4, a portion of the skirt portion 25 between the fourth and fifth journal walls 13d and 13e, that is, a portion adjacent to the opening of the passage 10 through which the blow-by gas flows is formed on the transmission coupling flange F. If it bulges toward the outer peripheral side and is connected to the transmission coupling flange F, the volume of the chamber in which the blow-by gas flows is increased, the oil separation effect from the blow-by gas is improved, and the transmission coupling flange F Can also contribute to the increase in rigidity.

In addition, the balancer shaft 17 is the cylinder block 1
It is inserted into the cylinder block from one cylinder row direction end (lower end in Fig. 4), but the diameter of the bearing hole is larger on the front side so that it can be inserted from one direction along the axial direction. And each bearing portion 20 of the balancer shaft 17
A to 20c are allowed to pass through in sequence.

As described above, according to the present invention, since the ventilation passage in the crankcase can be provided at a position avoiding the interference with the balancer shaft, the blow-by gas can be smoothly flowed and the skirt portion can be made to flow smoothly. If the portion that is adjacent to the opening of the passage is bulged toward the outer peripheral side of the transmission coupling flange and is connected to the transmission coupling flange, the volume of the chamber in which the blow-by gas flows is increased, and thus the blow-by gas blow-by is increased. The oil separation effect from the gas can be improved and the rigidity of the transmission coupling flange can be increased.

[Brief description of drawings]

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 sectional end view taken along the line III-III in FIG. FIG. 4 is a sectional end view taken along line IV-IV in FIG. FIG. 5 is a sectional view taken along line VV in FIG. 1, and FIG. 6 is a sectional view taken along line VI-VI. FIG. 7 is an end view of the cylinder block on the pulley side. 1 ... Cylinder block, 2 ... Cylinder block outer wall, 3 ... Cylinder block inner wall, 4 ... Water jacket, 5 ... Liner, 6a-6d ... Cylinder bore, 7 ...
… Cylinder head joint surface, 8 …… Bolt hole, 9 …… Crankcase, 10 …… Passage, 11 …… Lubricant oil discharge passage, 12 ……
Bearing part, 13a to 13e …… Journal wall, 14 …… Bolt hole,
15 …… Oil pan flange, 16 …… Bolt hole, 17 …… Balancer shaft, 18 …… Counterweight section, 19 …… Extension shaft section, 20a ・ 20c …… Bearing section, 21a ・ 21c …… Bearing hole, 22
…… Timing pulley, 23 …… Opening, 25 …… Skirt part, 26 …… Vacancy, 31 …… Crank shaft, 32 …… Crank pulley, 33 …… Timing belt, 34 …… Tension pulley,

Claims (1)

(57) [Claims] 1. A balancer shaft extending in the cylinder row direction on the side of a cylinder row composed of a plurality of cylinders arranged in series, and a ventilation passage in the crankcase extending along the axis of the cylinder. A cylinder block of an engine having, wherein the crankcase ventilation passage intersects with the axis of the balancer shaft at a position avoiding the balancer shaft on the side of the cylinder farthest from the connection portion of the balancer shaft with the crankshaft. And a space for accommodating the balancer shaft and a space for opening the ventilation passage in the crankcase are separated by a journal wall, and the ventilation passage in the crankcase is opened in the skirt portion of the cylinder block. The part adjacent to is bulged toward the outer periphery of the transmission coupling flange. A cylinder block of the engine, characterized in that it is connected to the transmission coupling flange.