JPH02211356A - Cylinder block for engine - Google Patents

Abstract

PURPOSE:To improve the cooling efficiency of a cylinder block and the quality of a casting by forming the contour of the section on the inner surface side of a bulging-out part and constituting the bottom of a water jacket so as to be positioned on the inner side of a crankcase from the top part of the bulging- out part. CONSTITUTION:The molten metal poured from an oil pan flange side flows into a part of a cylinder block outer wall 2 from a skirt 25, and the cylinder block outer wall 2 and the cylinder block inner wall 3 are formed by introducing the molten metal to the periphery of a water jacket core 27 for forming a water jacket 4 and the outer peripheral wall surface of a liner 5 to be casted into a cylinder block inner wall 3. Since the contour of the sectional surface of the connection part between the cylinder block outer wall and the skirt 25 is formed to an arcuate surface, together with the inner and outer surfaces, the generation of charge disorder can be obviated by improving the molten metal introducing performance to the lower edge part of the water jacket 4. Therefore, the low bottom formation of the water jacket 4 of the cylinder block made of aluminium alloy can be achieved, and the cooling efficiency and quality of a casting can be improved.

Description

[Detailed Description of the Invention] [Object of the Invention] <Industrial Application Field> The present invention relates to an engine cylinder block formed by pouring metal from a skirt portion, and in particular to an engine cylinder block formed by pouring metal from a skirt portion. The present invention relates to a cylinder block suitable for a counter balancer or the like in which a rotating shaft body is arranged adjacent to the side of a cylinder.

<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 with the
(See Publication No. 042, etc.). The position of this balancer shaft is preferably such that it does not interfere with the rotation locus of the balance weight portion formed in the crank web, and also does not increase the external dimensions of the cylinder block as much as possible. It is generally arranged at a position on the side of the cylinder that overlaps the end of the cylinder on the crankcase side, as shown in FIG.

<Problems to be Solved by the Invention> Incidentally, a skirt for forming the crankcase extends from the end of the cylinder on the crankcase side, but as described above, the balancer shaft is disposed on the side of the cylinder. In the case of a cylinder block installed in the cylinder block, in order to avoid interference with the balancer shaft, the skirt extends from the axially intermediate portion of the cylinder and bulges to the side of the cylinder to form a housing portion for the balancer shaft. It happens. As a result, the water jacket tends to be shallow, making it difficult to apply to aluminum alloy engine cylinder blocks that require particularly high cooling efficiency.

On the other hand, in long-stroke engines, the water jacket tends to be relatively deep, so in order to make the housing part of the balancer shaft bulge out to the side of the cylinder, it is necessary to add a skirt to the outer wall of the water jacket. The configuration must be such that the two are connected. However, when a cylinder block like the one described above is manufactured using a casting method in which molten metal is injected from the end face of the skirt, the molten metal that flows from the skirt into the outer wall of the water jacket is directed toward both ends of the cylinder in the axial direction. It is necessary to divide the flow into the following flow. However, since the outer wall of the water jacket is generally thin, smooth diversion of the molten metal in the same area tends to be hindered, and especially in the case of an aluminum alloy cylinder block that tends to solidify early, the molten metal It is conceivable that the filling quality may deteriorate, making it difficult to maintain casting quality. Furthermore, a lubricating oil passage must be provided inside the cylinder block, but if this lubricating oil passage is provided adjacent to the bottom of the water jacket, as disclosed in the above publication, the molten metal passage becomes even more complicated. The running performance of the hot water deteriorates, and even the rigidity of the bearing part of the balancer shaft decreases.

In view of these problems in the prior art, the main purpose of the present invention is to promote the deepening of the water jacket in order to improve cooling performance, and to improve the connection around the cylinder, especially between the outer wall of the cylinder block and the skirt. An object of the present invention is to provide an engine cylinder block that is improved so as not to deteriorate the casting quality in the vicinity of the cylinder block.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, such an object is achieved by providing a water jacket surrounding the cylinder and a water jacket disposed on the side of the cylinder in the crankcase. A cylinder block for an engine is formed by integrally molding a hollow bulging part for accommodating a rotating shaft body provided therein, the bulging part has an inner cross-sectional profile of An engine cylinder block, characterized in that the water jacket has an arc shape centered on the axis of the shaft body, and the bottom of the water jacket is located inside the crankcase rather than the top of the bulging part, or , the bulging portion extends from the outer wall of the water jacket, and the cross-sectional outline of the connecting portion of the bulging portion to the outer wall of the water jacket is arcuate, and the curvature of the arc is smaller than that of the outer surface. This is achieved by providing an engine cylinder block characterized by having a larger inner surface. In particular, it is preferable that the bulge is connected to the outer wall of the water jacket from a direction substantially perpendicular to the outer wall.

Furthermore, when the rotating shaft body is a pair of balancer shafts extending along the cylinder row on the side of the cylinder to cancel the excitation force of the reciprocating piston engine,
Preferably, a lubricating oil passage is formed outside the balancer shaft in the side wall of the cylinder block, parallel to the axis of the balancer shaft.

In this way, the cross-sectional shape of the connecting part of the hollow bulge to the outer wall of the water jacket becomes funnel-shaped,
The molten metal is smoothly divided in the same area. Therefore,
A deeper water jacket can be achieved by forming an accommodating portion for a balancer shaft or the like on the side of the cylinder. In particular, if the lubricating oil passage is formed on the outside of the balancer shaft, the formation of the lubricating oil passage will avoid affecting the molten metal passage around the water jacket or the strength of the bearing part of the balancer shaft. It is possible.

<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.
A liner 5 cast into the cylinder block inner wall 3 located inside the water jacket 4 forms cylinder bores 6a to 6d in which pistons (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 on a vehicle 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. Also, oil pan (not shown)
An oil pan flange 15 is formed facing outward on the lower surface of the cylinder block 1, which is ground to a flat surface for joining.

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 6b and 6C at the center in the cylinder row direction.
The first bearing portion 20a is disposed on the side of the first journal wall 13H 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 third and fourth cylinder bores 6C and 6c, and the third bearing part 20c is provided in the second and third cylinder bores. Third journal wall 13c between 6b and 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.

Additionally, second and third bearing portions 20b and 20c are provided on the second journal wall 13b between the first and second cylinder bores 6a and 6b.
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
A skirt 25 is formed to bulge toward both sides from a portion adjacent to the bottom of the water jacket 4 at point c. 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. In addition, a lubricating oil supply path 2 is provided in a portion of the outer wall of one of the skirts 25 adjacent to the balancer shaft 17.
A protrusion 29 having a shaft 8 provided therein extends parallel to the balancer shaft 17. This lubricating oil supply path 28 supplies lubricating oil under pressure by an oil pump (not shown) provided on the axial end wall of the cylinder block 1 to the lubricating oil discharge path 11 via an oil filter (not shown). It is for guidance.

Incidentally, the cylinder block 1 described above is formed by casting by injecting molten metal from the oil pan flange 15 side. The water jacket 4 is formed, for example, by inserting a mold core.

On the other hand, this water jacket is preferably formed over relatively the entire length of the cylinder bore in addition to improving cooling performance. Therefore, in the case of a cylinder block equipped with a balancer shaft on the side of the cylinder as shown in this embodiment, the top of the skirt, which is bulged to accommodate the balancer shaft, should be at a higher position than the bottom of the water jacket. is desirable.

Now, as shown in FIG. 7, the molten metal injected from the oil pan flange 15 side flows into the cylinder block outer wall 2 from the skirt 25, and around the water jacket core 27 to form the water jacket 4. ,
The cylinder block outer wall 2 and the cylinder block inner wall 3 are formed so as to be guided by the outer peripheral surface of the liner 5 that is cast into the cylinder block inner wall 3.

Here, the molten metal flowing from the skirt 25 to the outer periphery of the water jacket core 27 flows along the outer periphery of the water jacket core 27 toward the cylinder head joint surface 7 side, filling the cylinder block outer wall 2, and the other side flows into the outer periphery of the water jacket core 27. Water jacket 4 towards the bottom side of 4.
The area between the cylinder block inner wall 3 and the liner 5 is filled, and the lower end of the cylinder block inner wall 3 is also filled.

As can be seen from the flow of the molten metal described above, the molten metal separates at the portion where it flows from the skirt 25 into the cylinder block inner wall 3. The outer circumferential side of the water jacket 4 only needs to be filled up to the cylinder head joint surface 7, whereas the inner circumferential side of the water jacket 4 is filled from the bottom of the water jacket to the end of the cylinder block inner wall 3 on the crankcase side. Since it has to be filled, the amount of filling must be larger. Therefore, if the molten metal does not flow smoothly in this part, there is a risk that the casting quality will deteriorate.

Therefore, in the present invention, as shown in FIG.
The cross-sectional contour of the connection part with 5 is made into a circular arc surface on both the inner and outer surfaces, and in particular, the inner arc is approximately centered on the axis of the balancer shaft 17, and its curvature is made larger than the curvature on the outer surface (
Figure 7: R>r). By doing so, the cross-sectional shape of the portion from the skirt 25 to the cylinder block inner wall 3 becomes funnel-shaped, and the vertical division of the molten metal at the connection part is smoothed, and especially in the crankshaft of the cylinder block inner wall 3. The flow of molten metal to the end on the case side becomes smooth.

Furthermore, by extending the lubricating oil passage from the oil pump to the oil gear on the outer surface of the skirt, the formation of this passage may reduce the strength of the journal wall or affect the running performance around the cylinder. Inconvenience can be avoided.

[Effects of the Invention] As described above, according to the present invention, the flow resistance of the molten metal in the diversion section is suitably adjusted, and the flowability of the molten metal to the inner and outer peripheries of the water jacket, particularly to the lower end of the water jacket, is improved. This makes it possible to avoid filling defects.

Therefore, the water jacket in the aluminum alloy cylinder block can be deepened to improve the cooling efficiency of the cylinder block, and the casting quality of the cylinder block can be improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a cylinder block of an engine 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 line IV--IV in FIG. 3. FIG. 5 is a cut end view taken along the line v-■ in FIG. 1, and FIG. 6 is a cut end view taken along the same <Vl-Vl line. FIG. 7 is a partially enlarged sectional view. 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 ... Blank space 27 ...
・Water jacket core 28... Lubricating oil supply path 29... Allowed when protruding
Applicant: Representative of Honda Motor Co., Ltd.
Patent Attorney Yo Oshima - Figure 2 Figure 1 Figure 3 〆' Figure 5 7' Figure 6

Claims (4)

[Claims] (1) A water jacket surrounding the cylinder and a hollow bulge for accommodating the rotating shaft body disposed on the side of the cylinder in the crankcase are integrally molded by casting. In the engine cylinder block, the cross-sectional contour of the inner surface of the bulging portion is approximately in the shape of an arc centered on the axis of the rotating shaft body, and the bottom of the water jacket is connected to the bulging portion. A cylinder block for an engine, characterized in that the cylinder block is located inward of the crankcase from the top of the cylinder block. (2) A water jacket surrounding the cylinder and a hollow bulge for accommodating the rotating shaft body disposed on the side of the cylinder in the crankcase are integrally molded by casting. In the engine cylinder block, the bulging portion extends from an outer wall of the water jacket, and a cross-sectional outline of a connecting portion of the bulging portion to the outer wall of the water jacket is arcuate, and the bulging portion extends from the outer wall of the water jacket, and An engine cylinder block characterized in that the curvature of the inner surface is larger than that of the outer surface. (3) The engine cylinder block according to claim 1 or 2, wherein the bulging portion is connected from a direction substantially perpendicular to the outer wall of the water jacket. (4) The rotating shaft body is a pair of balancer shafts extending along the cylinder row on the side of the cylinder to cancel the excitation force of the reciprocating piston engine, and also supplies lubricating oil from the oil pump. 3. The cylinder block for an engine according to claim 1, wherein a passage is formed in a side wall of the cylinder block outside the balancer shaft in parallel with an axis of the balancer shaft.