JPH01167448A - Cooling device for cylinder liner - Google Patents

Abstract

PURPOSE:To execute the effective cooling by forming the oil passage grooves for cooling a cylinder liner as a plurality of stages constituted of a plurality of grooves and varying the number of grooves for each stage according to the necessity of cooling and suppressing the flow speed. CONSTITUTION:On the inner peripheral surface of a liner insertion hole 2 where the outer peripheral surface of a cylinder liner 3 is joined, plural stages A-D are dividingly formed by collecting a number of grooves 5-8 formed along the circumferential direction of the cylinder liner 3. Each groove which forms constitutes a same stage has the outputs 13-16 which are common to the common inlets 9-12. The number of grooves of the stages C and D having the larger cooling necessity is reduced, and the number of stages A and B having the less cooling necessity is increased. Therefore, the increase of the flow speed of the cooling lubricating oil is prevented, and the effective cooling is permitted according to the degree of necessity of cooling.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cooling device for a cylinder liner mainly used in an air-cooled engine, and particularly relates to a cooling device for cooling a cylinder liner by circulating oil around the outer peripheral surface of the cylinder liner. .

Conventional technology In the past, air-cooled engines were not designed to achieve such high output, and air cooling alone was sufficient to cool the cylinder liner, but with the recent increase in output, cooling of this liner has become There is a need to increase efficiency. In order to cool the outer circumferential surface of the cylinder liner, conventionally, a spiral groove is formed between the outer circumference of the cylinder liner and the cylinder block, and the cylinder liner is directly cooled by passing lubricating oil into this groove. (Refer to Utility Model Application Publication No. 1987-280'19)
.

Problems to be Solved by the Invention According to the conventional oil cooling method in which lubricating oil is passed through the grooves as described above, the boiling point of oil is higher than that in water cooling, so bubbles are generated due to boiling. There is an advantage that there is no uneven portion of each part of the liner, and deformation due to the uneven portion can be prevented. However, in conventional oil cooling systems that form spiral grooves, oil only passes through one spiral groove from the upper side of the liner to the lower side, so the cross-sectional area of the flow path becomes small. However, there is a problem in that the flow rate of oil becomes too high and cavitation occurs.

In this case, it is possible to increase the cross-sectional area by increasing the width or depth of the spiral groove to the extent that the flow velocity does not become too large, but in order to prevent a decrease in the strength of the liner or cylinder block. In addition, the wall thickness must be increased, resulting in an increase in weight.

In addition, in the case where oil passes through a single spiral groove as described above, the passage distance from the inlet to the outlet is long, and the temperature at the outlet side is considerably higher than that at the inlet side.
It is necessary to flow the cooling oil from the upper side of the liner where the degree of cooling required is greater toward the lower side, and there is a disadvantage that the direction of oil flow cannot be arbitrarily selected depending on the structure of the engine.

In view of the problems of the conventional oil cooling system, this invention prevents the flow rate of oil passing around the cylinder liner from becoming too large, and furthermore, prevents oil from flowing in areas that require cooling, such as the upper part of the cylinder liner. The purpose of the present invention is to provide an oil-cooled type cooling device in which cooling efficiency is increased by increasing the flow velocity, and the flow velocity can be reduced in the lower part of the liner where the necessity is small.

Means for Solving the Problems And in order to achieve this objective, the present invention provides a cylinder liner (1) inserted into the cylinder block (1).
3) A number of oil passages 1 (5) to (8) along the circumferential direction of the cylinder liner (3) are formed independently from each other on one or both sides of the outer peripheral surface and the inner peripheral surface of the cylinder block (1). death,
Each of these /JI (5) to (8) is attached to the cylinder liner (
3) Depending on the degree of cooling required in each area, the number of grooves is reduced in areas where cooling is required, and the number of grooves is increased in areas where cooling is required, thereby creating multiple grooves that all have a common entrance. The system is characterized in that it is divided into several stages A to D each having a component, and the entrances and exits between these stages A to D are sequentially connected.

According to the configuration of the present invention described above, the independently formed Zendos (5) to (8) are connected to the stage A each having a common entrance.
- Since the lubricating oil is grouped by D, in each stage A-D, the lubricating oil flows through multiple passages at the same time, which increases the flow passage cross-sectional area and prevents the flow velocity from becoming too high. be able to. In addition, for areas that require a large amount of cooling, the number of grooves is reduced to increase the flow velocity, thereby increasing the cooling effect, and for areas that require less cooling, the number of constituent grooves is increased to reduce the flow velocity ( Therefore, effective cooling can be performed depending on the degree of cooling required.

Embodiment Next, an embodiment in which the structure of the present invention is applied to an air-cooled engine will be described. In FIGS. 1 and 2, (1) is a cylinder block, and a cylinder liner (3) is inserted into a liner insertion hole (2) of this cylinder block (1). A large number of cooling fins (4) (4)... are formed on the outside of the cylinder block (1). The inner circumferential surface of the liner insertion hole (2) has a large number of grooves (5) to (8) along the circumferential direction of the cylinder liner (3) at the joint surface with the outer circumferential surface of the cylinder liner (3). They are formed independently of each other and at intervals in the vertical direction.

As mentioned above, in this invention, these grooves (5) to (
8) is divided into several stages by grouping a plurality of them, and the grooves indicated by the same reference numerals in the figure are formed so as to be the same stages. That is, the three grooves on the lower side indicated by the symbol (8) constitute the first stage A, and the three grooves on the upper side indicated by the symbol (7) constitute the first stage A.
The second stage B is constituted by the groove of the book, and further has the symbol (6).
) The two grooves indicated by the symbol (5) form the third stage C.
The two grooves at the upper end constitute the fourth stage D, and the guides constituting the same stage have common entrances (9) to (12) and common exits (13) to (
16). In this embodiment, cooling lubricating oil is flowed from the lower first stage A to the upper fourth stage D, and the inlet of the first stage A (
16) is released to the outside through the piping connection hole (17),
An outlet (13) of the fourth stage D is opened to the outside through a pipe connection hole (20). Then, along the flow direction of the cooling oil, the outlets (13) to (15) of the upstream stage
) are mutually communicated with the inlets (10) to (12) of the downstream stages via communication portions (21) to (23), respectively.

Therefore, the cooling oil first enters the three grooves (8) simultaneously from the common inlet (16) in the first stage A, and flows through these grooves (8) in parallel toward the outlet (12). After flowing, it enters the common entrance (15) of the second stage B via the connecting channel (21).

Similarly, after flowing in parallel through the three grooves (7) of the second stage B, it enters the inlet (14) of the third stage C through the communication path (22) from its inlet (11). In this third stage, there are two grooves, and after flowing through the two grooves (6) in parallel, the water passes through the outlet (10) and the communication path (23), and then flows through the fourth groove (6).
From the inlet (9) of stage D through the groove (5) to the outlet (1
3) It flows out to the side.

Therefore, in the above configuration, since the cooling oil flows simultaneously through the plurality of grooves in each stage, the cross-sectional area of the flow passage becomes large, and the drawback that the flow velocity becomes too high can be prevented. In addition, the third stage C, which requires a large amount of cooling,
The number of grooves in the fourth stage D is two, and the number of grooves in the first and second stages A-D, which require less cooling, is three each. The flow rate increases, thereby increasing the cooling effect of the high temperature part, resulting in a structure with high cooling efficiency as a whole. System oil such as engine lubricating oil is normally used as such cooling oil, and the pipe connection hole (17
) Circulate oil through piping etc. connected to (20).

In the above embodiment, the intervals, that is, the pitches between the pitches (5) to (8) are the same, but the pitch is not necessarily limited to this, and it is also possible to change the pitch. Furthermore, grooves (5) to (8) are formed on the inner circumferential surface (2) of the cylinder block (1), but these may be on the cylinder liner (3) side, or on both surfaces. It is also possible to form a Furthermore, in this embodiment, the cylinder liner (3) and the cylinder block (1) are formed separately and inserted into the cylinder liner (3), but by doing so, the groove ( 5) ~ (8)
formation becomes easy. That is, in the case of an integrally formed one, it is necessary to use a complicated core to form the groove, but by forming the groove separately, this drawback can be avoided and the product can be manufactured at a low cost.

Effects of the Invention As described above, in this invention, since the oil flows simultaneously through a plurality of grooves in each stage, the flow velocity of the cooling oil does not become too high, and compared to the conventional method, This has the effect of preventing the occurrence of cavitation. Furthermore, since the number of grooves in each stage is changed depending on the cooling needs of each part of the cylinder, the flow velocity can be increased by reducing the number of grooves in the upper part of the cylinder liner, which is a high temperature area. In addition to increasing the cooling effect, the number of tubes is increased in the lower part, which is the low-temperature section, to reduce the flow velocity, thereby achieving the effect of reducing overcooling and passage resistance. In addition, since the cross-sectional area of the flow path is changed by changing the number of grooves, there is no need to consider the reduction in strength of the cylinder block or cylinder liner as much as compared to the case where the cross-sectional area of one groove is increased. There is no increase in weight due to increase in wall thickness.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a cylinder liner portion in an embodiment of the invention, and FIG. 2 is a sectional view taken along the line A--A in FIG. 1. (1)...Cylinder block, (2)...Cylinder block inner peripheral surface, (3)...Cylinder liner, (5)-(8)...Groove, (9)-(1)
2)...Inlet, (13) to (16)...Exit, (2
1) to (23)...Connection path, A-D...Cooling stage.

Claims (1)

[Claims] A number of grooves for oil passages along the circumferential direction of the cylinder liner are formed independently from each other on one or both sides of the outer peripheral surface of the cylinder liner inserted into the cylinder block and the inner peripheral surface of the cylinder block, and each of these grooves Depending on the degree of cooling required in each part of the cylinder liner, the number of grooves is reduced in areas that require more cooling, and the number of grooves is increased in areas that require less cooling. A cylinder liner cooling device characterized in that it is divided into several stages each having a groove as a component, and the inlets and outlets between the stages are sequentially connected.