JP2505193Y2 - Engine cylinder block - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an engine cylinder block.

[Conventional technology]

Generally, a cylinder block of an engine has a cylinder wall forming a plurality of cylinders, a lower crankcase, front and rear ends of the crankcase, a bulkhead arranged between the cylinders, and the like, and a bearing portion provided on each bulkhead. The crankshaft is supported on the.

In this type of cylinder block, for example, JP-A-62-62
As disclosed in Japanese Patent No. 139951, there is known a structure in which a thinned portion is provided in a bulkhead below a cylinder wall between cylinders in order to reduce weight and reduce pumping loss. According to this structure, the spaces below the pistons of the cylinders are communicated with each other at the lightening portions, air is allowed to flow between them, and the resistance when the pistons reciprocate is reduced.

[Problems to be solved by the device]

By the way, in the above conventional structure, the bulkhead on the front end side of the cylinder block is formed so as to shield the inside of the cylinder block from the space in front of the cylinder block, and only in the bulkhead located between the cylinders. Although the lightening portion (communication hole) is provided, the size of the lightening portion is limited to some extent in terms of rigidity, etc., so that the opening area to the space below the front end side cylinder is insufficient and the pumping loss reduction effect is achieved. May not be obtained sufficiently.

Further, in front of the cylinder block, a drive system for transmitting the rotation of the crankshaft to the camshaft and the like is arranged,
As the drive system, there are conventionally known a drive system using a timing belt and a drive system using a chain having higher durability. Among these, in the case of using the timing belt, in order to prevent the adhesion of oil to the belt having poor oil resistance, it is necessary to shut off the timing belt installation portion and the space below the cylinder.
In the case of using a chain, it is required to improve lubricity by supplying oil to the chain.

In view of such circumstances, the present invention is directed to a structure in which a chain is arranged in front of a cylinder block, and provides an engine cylinder block capable of enhancing a pumping loss reduction effect and a lubrication effect on the chain. The purpose is to

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention has bulkheads having bearing portions arranged at a plurality of positions of a cylinder block, the crankshaft is supported by the bearing portions of the bulkheads, and the moving parts of the engine are In an engine in which a driving chain is wound around a sprocket on a crankshaft and arranged in a chain case in front of a cylinder block, a bulkhead at the front end of the cylinder block is provided with a space below the front end side cylinder in the cylinder block and the chain case. A communication hole that communicates with the inside is provided.

[Action]

According to the above configuration, in the cylinder on the front end side of the cylinder block, air is circulated between the lower space of the cylinder and the inside of the chain case according to the reciprocating movement of the piston, and the air is circulated. Accordingly, the oil existing in the space below the cylinder is fed into the chain case.

〔Example〕

1 and 2 show an embodiment of the present invention. In these figures, a cylinder block 1 has a plurality of cylinders 2 surrounded by a cylinder wall 3, and a piston 4 is inserted into each cylinder 2 and the piston 4 is attached to a crankshaft 6 via a connecting rod 5. It is connected. A crankcase for accommodating the crankshaft 6 is formed in the lower portion of the cylinder block 1, and bulkheads 7, 8 which are continuous with the cylinder wall 3 and project downward are formed at positions between the front and rear ends of the crankcase 6 and the cylinders. Are integrally provided, and each of the cylinders 2 is provided by these bulkheads 7 and 8.
The space below is partitioned. A bearing portion 9 is provided at the center of the lower end of each of the bulkheads 7 and 8, and a bearing cap 10 is fixed to the bearing portion 9 with a bolt.
The crankshaft 6 is supported by the bearing cap 10 and the bearing cap 10. At the lower end of the cylinder block 1, a bearing cap 10 and a reinforcing member 11 for connecting both side wall portions of the cylinder block are fixed by bolts or the like, and an oil pan (not shown) is attached. There is.

A chain 12 for driving a cam shaft (not shown) as a moving part of the engine is arranged in front of the cylinder block 1. The chain 12 is wound around a sprocket 13 attached to the crankshaft 6 in a chain case 14. Above chain case
A chain cover 14a constituting 14 is formed of aluminum alloy or the like and attached to the front surface of the cylinder block 1, and the sprocket 13 is supported by the chain cover 14a via a bearing 15. An oil pump 16 is arranged behind the chain 12 in the chain case 14, and a pulley 17 is attached to the front end of the crankshaft 6 projecting forward of the chain cover 14a. A belt 18 for driving is wound around.

The bulkhead 7 at the front end of the cylinder block 1 located on the rear surface side of the chain case 14 is provided with a communication hole 20 for communicating the space below the front end side cylinder 2 in the cylinder block 1 and the inside of the chain case 14. ing. Also, in the figure, the bulkhead 8 located between the cylinders
Communication hole 21 for communicating the lower spaces of adjacent cylinders 2 with each other
Is provided.

According to such a structure of this embodiment, in addition to the communication hole 21 of the bulkhead 8 between the cylinders 2 on the front end side of the cylinder block 1, the communication hole 20 is also connected to the bulkhead 7 on the front end of the cylinder block 1. Since the space is provided, the space in the chain case 14 is effectively used and the pumping loss is reduced. That is, according to the vertical movement of the piston 4 in the cylinder 2 on the front end side, air flows out from the lower space when the piston descends, and air flows into the lower space when the piston rises, and the lower space and the chain case. Air is circulated to and from 14 through the communication hole 20, whereby pumping loss is reduced.

Furthermore, the communication hole 20 also serves to lubricate the chain 12 with the oil existing in the space below the cylinder 2. In other words, in the lower space, a large amount of oil injected from the oil jet for cooling the piston and end flow oil from the crankshaft lubrication portion is mixed in the air, so the oil passes through the communication hole 20 from the lower space. When the air flows out into the chain case 14, the oil mixed with this air and passing through the communication hole 20
It is supplied to the chain 12 in 14 (arrow in FIG. 2), and the lubricity of the chain 12 is enhanced.

Further, if the bulkhead 7 at the front end of the cylinder block 1 is provided with the communication hole 20, the rigidity of the bulkhead 7 is lowered, but a highly rigid chain cover 14a made of aluminum alloy or the like is attached to the front surface of the cylinder block 1. By doing so, the front end side of the cylinder block 1 is reinforced by the chain cover 14a, and the rigidity reduction of the bulkhead 7 is sufficiently compensated, so that vibration noise on the front end side of the crankshaft 6 is not increased. .

[Effect of device]

As described above, the present invention provides an engine in which the chain wound around the crankshaft sprocket is arranged in the chain case in front of the cylinder block.
Since the bulkhead at the front end of the cylinder block has a communication hole that connects the space below the front end side cylinder in the cylinder block and the inside of the chain case, the volume change of the space below the front end side cylinder due to the operation of the piston. According to the above, air is circulated between the space and the space in the chain case through the communication hole,
The pumping loss is sufficiently reduced, and oil is sent into the chain case from the space below the front end side cylinder to improve the lubricity of the chain.

[Brief description of drawings]

FIG. 1 is a sectional view of a front end side portion of a cylinder block according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of an essential part of the cylinder block. 1 ... Cylinder block, 2 ... Cylinder, 7 ... Bulkhead at the front end of the cylinder block, 12 ... Chain, 13
...... Sprocket, 14 ...... Chain case, 20 ...... Communication hole.

Claims (1)

(57) [Scope of utility model registration request] Claims: 1. A bulkhead having bearing portions is arranged at a plurality of positions of a cylinder block, a crankshaft is supported by the bearing portions of these bulkheads, and a chain for driving moving parts of an engine is a sprocket of the crankshaft. In the engine wound around the cylinder block and arranged in the chain case in front of the cylinder block, the bulkhead at the front end of the cylinder block has a communication hole for communicating the space below the front end side cylinder in the cylinder block with the inside of the chain case. An engine cylinder block characterized by being provided.