JPH10318039A - Cylinder block for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deformation of a cylinder block outer wall when a cylinder head is installed on a cylinder block by a head bolt, and reduce oil consumption. SOLUTION: In an open deck type cylinder block 10 of an internal combustion engine in which a cylinder bore 2 and a cylinder block outer wall 9 are separated from each other in an upper deck 5, an upper deck 5A of the cylinder block outer wall 9 is formed in such a constitution that the width is enlarged matching with a deforming mode of the cylinder block 10 when the cylinder head is installed so as to improve rigidity gradually in a direction approaching from both end parts in a longitudinal direction of the engine to a center part, and its width is enlarged so as to improve the rigidity gradually in a direction approaching from both end parts in a width direction of the engine to the center part. As a result, an oil consumption is reduced. A fuel consumption is improved, and an engine output is increased, in the case where the oil consumption is set to the same level as that of a prior art.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block of an internal combustion engine, and more particularly to a deformation of an outer wall of a cylinder block of a multi-cylinder internal combustion engine having an open deck structure when the cylinder head is assembled to the cylinder block with a head bolt. The present invention relates to a cylinder block of an internal combustion engine capable of suppressing the occurrence of an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, in order to improve the cooling efficiency of a cylinder block of an internal combustion engine and to reduce the weight of the cylinder block, a cylinder wall forming a cylinder bore and an outer wall of the cylinder block are provided with water on their top surfaces (upper deck). 2. Description of the Related Art A cylinder block having a double open deck structure (hereinafter, referred to as an open deck type cylinder block) separated by a jacket has been put to practical use. A cylinder head is attached to the upper part of such an open deck type cylinder block with a gasket interposed therebetween, and the cylinder head is fastened to a fastening boss portion of the head bolt provided on the outer wall of the cylinder block by a head bolt.

FIG. 7A shows the structure of a main part of a conventional open deck type cylinder block 20. As shown in FIG. The cylinder block 20 in this example is for a four-cylinder internal combustion engine, and is composed of an upper block 4 and a lower block 6, and the top surface of the upper block 4 is an upper deck 5. In this open deck type cylinder block 20, the cylinder wall 2a and the cylinder block outer wall 9 are separated from each other in the upper deck 5, and the cylinder bore 2
The water jacket 3 is formed between the outer jacket 9 and the outer wall 9 of the cylinder block. Cylinder block 20 of this example
Is also a Siamese type cylinder block in which adjacent cylinder walls 2a are integrated. Further, a head bolt hole 1 for attaching a head bolt (not shown) and a boss portion 8 provided with an oil return hole 7 are formed on the cylinder block outer wall 9. Here, reference numerals # 1 to # 4 assigned in the cylinder bore 2 indicate cylinder numbers of a four-cylinder internal combustion engine, and # 1 indicates a first cylinder.

A cylinder head is mounted on the upper deck 4 of the open deck type cylinder block 20 via a gasket with a head bolt (illustration of the gasket, the cylinder head, and the head bolt is omitted). ). When the cylinder head is assembled to the cylinder block 20, the outer wall 9 of the cylinder block 20 of the cylinder head 20 is deformed in the thrust and anti-thrust directions as shown in FIG. Is substantially egg-shaped (the oil return hole 7 is not shown in FIG. 7B). That is, the bosses 8a at the four corners of the cylinder block outer wall 9 are deformed inward, and the other bosses 8b are moved outward, so that the cylinder block outer wall 9 is deformed substantially in an egg shape. Then, the lower block 6 is deformed along with the substantially oval deformation of the cylinder block outer wall 9, and the cylinder bore 2 is also deformed.

If such deformation occurs when the cylinder head is assembled to the cylinder block 20, there is a problem that the sealing performance of the head gasket becomes imperfect, oil leaks, and oil consumption increases. To solve this problem, Japanese Patent Application Laid-Open No. 8-28343 discloses that FIG.
As shown in the figure, the inner wall surface of the cylinder block outer wall 9 and the outer wall surface of the cylinder wall 2a forming the cylinder bore 2 are connected by ribs 11 to prevent deformation of the cylinder block when the cylinder head is assembled to the cylinder block 20. (In FIG. 7 (c), the illustration of the oil return hole 7 is omitted).

[0006]

However, in the technique described in Japanese Patent Application Laid-Open No. 8-28343, since the ribs 11 are provided in the water jacket 3, the shape of the water jacket 3 is limited. There is a problem that the flow of the cooling water flowing in the water jacket 3 is also deteriorated.

Accordingly, an object of the present invention is to provide a cylinder block of an internal combustion engine having an open deck structure capable of preventing deformation of the upper deck even when the cylinder head is mounted on the cylinder block with a head bolt. .

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a cylinder block of an internal combustion engine having an open deck structure in which a cylinder bore and an outer wall of a cylinder block are separated from each other at an upper portion. The engine is characterized in that the rigidity gradually increases from both ends in the longitudinal direction toward the center, and the rigidity gradually increases from both ends in the width direction of the engine toward the center.

The rigidity of the upper deck may be changed so as to suppress the deformation in accordance with the deformation mode of the upper deck when the cylinder head is mounted on the upper portion of the cylinder block. The change in the rigidity may be such that the width of the upper deck portion in the longitudinal direction of the engine and the width of the upper deck portion in the direction orthogonal to the longitudinal direction of the engine are gradually increased from both ends toward the center. . Further, specifically, the outer peripheral shape of the upper deck portion may be substantially elliptical.

According to the present invention, the upper deck portion of the cylinder block of the internal combustion engine having the open deck structure is reinforced so as to have high rigidity in accordance with the deformation mode when the cylinder head is assembled thereon. Deformation of the cylinder block when assembling the cylinder head is prevented.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG.
(a) shows the configuration of a cylinder block 10 of an internal combustion engine according to one embodiment of the present invention, and is a plan view of an upper deck 5A of the cylinder block 10. FIG.
1B is a side view of the cylinder block 10 shown in FIG. 1A, and FIG. 1C is a perspective view of the upper block 4 of the cylinder block 10 shown in FIG. In this embodiment, the same components as those of the conventional cylinder block 20 described with reference to FIG.

Also in the open deck type cylinder block 10 of this embodiment, the cylinder wall 2a and the cylinder block outer wall 9 are separated from each other by the water jacket 3 in the upper deck 5A, as shown in FIGS. The cylinder block 10 of this embodiment is a Siamese type cylinder block in which adjacent cylinder walls 2a are integrated. Further, the upper deck 5A is provided with a head bolt hole 1 for attaching a head bolt (not shown) and an oil return hole 7.

In such an open deck type cylinder block 10, in this embodiment, the upper deck 5A above the cylinder block outer wall 9 gradually becomes wider from both ends E in the longitudinal direction LL of the engine to the center C. Is increased so that its rigidity is increased. At the same time, the rigidity of the engine is increased by gradually increasing the width from the both ends C to the center E in the width direction SS of the engine. The enlargement ratio of this width is about 1/30 of the length and width of the engine on one side. That is, when the length of the engine in the longitudinal direction is set to 30, the lateral width is widened by two. At this time, as shown in FIG. 1B, the thickness of the upper deck 5A is kept constant.

The rigidity of the upper deck 5A is such that this deformation is suppressed in accordance with the deformation mode applied to the cylinder block outer wall 9 when the cylinder head is assembled on the upper portion of the cylinder block 10 with a head bolt via a gasket. Should be changed to For example, the deformation mode of the cylinder block outer wall 9 when the cylinder head is mounted on the upper portion of the cylinder block 10 is shown in FIG.
(a) Consider a case where the shape is a substantially elliptical shape indicated by a solid line 9B. In such a case, the outer shape of the upper deck 5A may be substantially elliptical as indicated by reference numeral 5B in FIG.

Further, it is assumed that the deformation mode of the cylinder block outer wall 9 when the cylinder head is mounted on the upper portion of the cylinder block 10 is a substantially elliptical shape shown by a solid line 9C in FIG. In such a case, the outer shape of the upper deck 5A may be substantially elliptical as indicated by reference numeral 5C in FIG. 3B in accordance with the deformation mode of the outer wall 9 of the binder block.

As described above, the outer shape of the cylinder block outer wall 9 is made in accordance with the deformation mode of the cylinder block outer wall 9 when the cylinder head is mounted on the upper portion of the cylinder block 10, thereby increasing the rigidity of the cylinder block outer wall 9. For example, even in an open deck type cylinder block, deformation of the cylinder block outer wall 9 at the time of assembling the cylinder head is prevented, and inclination of the head bolt is prevented. As a result, the sealing performance of the head gasket is improved, the deformation of the cylinder bore 2 can be reduced, and the consumption of oil is reduced.

FIG. 4 is a characteristic diagram showing a comparison between a change in the engine speed and a change in the oil consumption rate of the cylinder block 10 of the present invention and the conventional cylinder block 20.
As can be seen from this characteristic diagram, the oil consumption rate of the cylinder block 10 of the present invention shown by the solid line is about 50% as compared with the oil consumption rate of the conventional cylinder block 20 shown by the dashed line.
decreasing.

FIG. 5A shows a cylinder block 10 according to the present invention.
FIG. 7 is a characteristic diagram showing a change in oil consumption rate when the total piston ring tension is changed between the conventional cylinder block 20 and a conventional cylinder block 20. Here, comparing the total piston ring tension at a predetermined oil consumption rate X, the total piston ring tension is T1 in the cylinder block 10 of the present invention.
On the other hand, in the conventional cylinder block 20, the total piston ring tension is T2 which is much larger than T1.

FIG. 5B is a characteristic diagram showing a fuel efficiency improvement ratio characteristic with respect to the magnitude of the total piston ring tension. As can be seen from this figure, the smaller the total piston ring tension, the higher the fuel efficiency improvement rate. Therefore, when the total piston ring tension is reduced to T1 so that the oil consumption rate is substantially the same as the conventional one, the fuel efficiency is improved by 1% as can be seen from FIG. 5 (b).

FIG. 6 is a characteristic diagram showing the magnitude of the engine performance torque with respect to the change in the engine speed of the cylinder block 10 of the present invention and the conventional cylinder block 20 in comparison. From this figure, it can be seen that the cylinder block 10 of the present invention
It can be seen that the engine that employs the above has higher engine performance torque indicated by the solid line than the engine that employs the conventional cylinder block 20 indicated by the dashed line.

As described above, according to the cylinder block of the present invention, since the oil consumption can be reduced, the tension of the piston ring can be reduced, so that friction can be reduced, fuel consumption can be improved, and engine output can be reduced. Increase can be achieved.

[0022]

As described above, according to the present invention,
Since the upper deck of the open deck type cylinder head is configured such that the rigidity of the central portion in the engine longitudinal direction and the central portion in the engine width direction gradually increases from both ends in each direction,
When the cylinder head is assembled to the cylinder block with the head bolts serving as fastening members, the rigidity of the upper deck corresponds to the deformation distribution of the cylinder block outer wall. As a result, the upper deck is prevented from being deformed when the cylinder head is mounted on the cylinder block with the head bolt, and the oil consumption can be reduced. At this time, there is no influence of the shape of the cooling water channel. Further, since the oil consumption can be reduced, the tension of the piston ring can be reduced, and there is also an effect that friction can be reduced, fuel efficiency can be improved, and engine output can be increased.

[Brief description of the drawings]

1 (a) is a plan view of an upper deck of a cylinder block showing a configuration of an embodiment of a cylinder block of an internal combustion engine of the present invention, FIG. 1 (b) is a side view of the cylinder block of FIG. 1 (a),
(c) is a perspective view of a main part of the cylinder block of (a).

FIG. 2A is an explanatory view showing an example of a modification of the upper deck when the cylinder head is assembled to the upper deck of the cylinder block, and FIG. 2B is a diagram of the upper deck of the cylinder block of the present invention corresponding to the modification of FIG. It is a top view.

3A is an explanatory view showing another example of the deformation of the upper deck when the cylinder head is assembled to the upper deck of the cylinder block, and FIG. 3B is a diagram of the cylinder block of the present invention corresponding to the deformation of FIG. It is a top view of an upper deck.

FIG. 4 is a characteristic diagram showing a comparison between a change in the engine speed and a change in the oil consumption rate of the cylinder block of the internal combustion engine of the present invention and a conventional cylinder block.

5A is a characteristic diagram showing a change in oil consumption rate when the total piston ring tension of the cylinder block of the internal combustion engine of the present invention and the conventional cylinder block is changed, and FIG. FIG. 4 is a characteristic diagram showing a fuel efficiency improvement rate characteristic with respect to a magnitude of a piston ring tension.

FIG. 6 is a characteristic diagram showing, in comparison, the magnitude of engine performance torque with respect to a change in engine speed of a cylinder block of an internal combustion engine of the present invention and a conventional cylinder block.

FIG. 7A is a perspective view of a main part of a conventional open deck cylinder block, and FIG. 7B is an explanatory view showing a deformation of an upper deck when a cylinder head is assembled to the conventional open deck cylinder block. FIG. 3C is a plan view of an upper deck portion of a cylinder block showing a conventional example for suppressing the deformation of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Head bolt hole 2 ... Cylinder bore 3 ... Water jacket 4 ... Upper block 5 ... Upper deck 6 ... Lower block 9 ... Cylinder block outer wall 10 ... Cylinder block of the present invention 20 ... Conventional cylinder block

Claims (4)

[Claims] 1. A cylinder block of an internal combustion engine having an open deck structure in which a cylinder bore and an outer wall of a cylinder block are separated from each other at an upper portion. The cylinder block of the internal combustion engine is characterized in that the rigidity gradually increases from the both ends in the width direction of the engine toward the center. 2. The cylinder block for an internal combustion engine according to claim 1, wherein the rigidity is adjusted in accordance with a deformation mode of the upper deck portion when a cylinder head is mounted on an upper portion of the cylinder block. A cylinder block for an internal combustion engine, wherein the cylinder block is changed so as to suppress deformation. 3. The cylinder block for an internal combustion engine according to claim 2, wherein the change in the rigidity is determined by determining a width of the upper deck portion in a longitudinal direction of the engine and a width in a direction orthogonal to the longitudinal direction of the engine. A cylinder block for an internal combustion engine, wherein each of the cylinder blocks is configured to be gradually increased from both ends to the center. 4. The cylinder block of an internal combustion engine according to claim 3, wherein an outer peripheral shape of the upper deck portion is substantially elliptical.