JP2849962B2 - Cylinder liner cooling structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder liner cooling structure for an internal combustion engine.

[0002]

2. Description of the Related Art Generally, a cylinder liner of an internal combustion engine is provided with a water jacket around an outer peripheral surface thereof, and heat generated during operation of the engine is usually cooled by water. However, in the water jacket system, the upper portion is insufficiently cooled under high rotation and high load operation conditions. For this reason, there is a limit to the high performance of the engine. Therefore, recently, a cooling method of pumping a coolant of water or oil into a groove provided around the outer peripheral surface of the cylinder liner has been studied.

[0003]

In this case, the coolant is
The outer peripheral surface of the cylinder liner can be cooled by forced convection heat transfer which is much larger than the natural convection heat transfer of the water jacket system. Therefore, various groove arrangements have been studied in order to realize an optimal cooling state according to each axial portion of the cylinder liner.

Here, the change caused by the difference in the cooling liquid will be described. In the case of water, the cooling performance during high-speed operation is excellent, but the warm-up characteristics are slightly poor. As for the heat exchanger of the cooling water, a conventional radiator can be used as it is. In the case of oil, the warm-up characteristics are excellent, but the cooling performance during high-speed operation is inferior to that of water cooling. Further, in the case of oil cooling, there is a disadvantage that the oil cooler, which was conventionally small, must be changed to an extremely large one.

Hitherto, proposals for a cooling structure of a cylinder liner using both oil cooling on the inside and a water cooling jacket on the outside have been made, for example, in Japanese Utility Model Laid-Open No. 56-117038 and Japanese Utility Model Laid-Open No. 60-17038.
No. 173650, none of which can completely cool the cooling oil with a water-cooled jacket and requires a separate large oil cooler. This is because the cooling of the jacket structure is based on natural convection heat transfer, and the cooling performance is not so great.

An object of the present invention is to provide a cooling structure of a cylinder liner which is excellent in warm-up characteristics and cooling performance during high-speed operation.

[0007]

According to the structure of the present invention, a cylinder liner inserted into a bore of a cylinder block has a double cylinder structure of an inner cylinder and an outer cylinder. A groove for a cooling oil passage is formed on one or both of the inner peripheral surfaces, and a groove for a cooling water passage is formed on one or both of the outer peripheral surface of the outer cylinder and the inner peripheral surface of the bore of the cylinder block. It is characterized by having.

[0008]

The cooling oil flowing through the groove at the boundary between the inner and outer cylinders of the cylinder liner of the present invention has a low specific heat, so that the warm-up characteristics are improved. The heat of the inner cylinder of the cylinder liner raises the oil temperature of the cooling oil, and this cooling oil is forcibly cooled by cooling water flowing through a groove at the boundary between the outer cylinder of the cylinder liner and the inner peripheral surface of the bore of the cylinder block. Since the cooling performance of the cooling water flowing through the grooves is excellent, the cooling performance during high-speed operation is good, and an oil cooler of a special size for the cooling oil is not required. The cooling water can be cooled with the same radiator as before.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a cylinder liner 1 fitted in a bore of a cylinder block 16 has a double cylinder structure of an inner cylinder 2 and an outer cylinder 3, and the inner cylinder 2 has excellent wear resistance and sliding characteristics. The outer cylinder 3 is made of cast iron and is made of steel having excellent strength. Since the cylinder liner 1 has a double cylinder structure, it is possible to minimize an increase in the pitch between bores.

Hereinafter, the configuration of the inner cylinder 2 will be described with reference to FIGS. The inner cylinder 2 has a flange 4 at an upper end, and twelve annular grooves 6 are formed on the outer peripheral surface 5 of the liner below the flange 4 at intervals in the axial direction. And these annular grooves 6
Is divided into three annular groove groups.

The three annular groove groups include a first annular groove group 6A from the first annular groove 6 to the third annular groove 6 on the upper end side of the liner, and a fourth annular groove 6 to the seventh annular groove. A second annular groove group 6B up to the annular groove 6, and a third annular groove group 6C from the eighth annular groove 6 to the last twelfth annular groove 6.

In the first annular groove group 6A, two vertical grooves 7, 8 for connecting the annular grooves 6 to each other are formed at two positions separated by 180 degrees in the liner circumferential direction. The groove 7 forms the inlet for the coolant and the other longitudinal groove 8 forms the outlet for the coolant.

Similarly, in the second annular groove group 6B, two vertical grooves which communicate the annular grooves 6 with each other at the same two positions in the circumferential direction as the longitudinal grooves 7, 8 of the first annular groove group 6A. Directional grooves 9 and 10 are formed, and a vertical groove 9 located on the coolant outlet side of the first annular groove group 6A forms a coolant inlet, and the other longitudinal groove 10 forms a coolant outlet.

Similarly, the third annular groove group 6C has two annular grooves 6 communicating with the longitudinal grooves 9, 10 of the second annular groove group 6B at the same two positions in the circumferential direction. Vertical grooves 11 and 12 are formed, and the vertical groove 11 located on the coolant outlet side of the second annular groove group 6B serves as a coolant inlet, and the other vertical groove 12 serves as a coolant outlet. Eggplant

The vertical grooves 8 forming the outlet of the coolant in the first annular groove group 6A and the vertical grooves 9 forming the inlet of the coolant in the second annular groove group 6B are formed by these vertical grooves 8 , 9 are communicated in series by a vertical groove 13 provided at the same position in the circumferential direction.

Similarly, the vertical grooves 10 forming the outlet of the cooling liquid of the second annular groove group 6B and the vertical grooves 11 forming the inlet of the cooling liquid of the third annular groove group 6C are formed by these vertical grooves. Direction groove 1
0 and 11 are connected in series by a vertical groove 14 provided at the same position in the circumferential direction.

In the lower portion of the outer peripheral surface 5 of the liner, a vertical groove 15 for discharge communicating with the vertical groove 12 forming the outlet of the third annular groove group 6C is formed to the lower end.

The inner cylinder 2 is fitted in the outer cylinder 3, and the space defined by the grooves 6 to 15 formed in the outer peripheral surface 5 of the inner cylinder 2 and the inner peripheral surface 30 of the outer cylinder 3 is cooled. An oil passage 29 is formed. The outer cylinder 3 is fitted in a bore of the cylinder block 16.

As shown in FIG. 2, a cooling oil pipe insertion hole 18 is formed in the upper part of the cylinder block 16 in the lateral direction, one end of which is opened on the outer periphery of the cylinder block 16 and the other end is formed of the cylinder block. An opening 16 is formed on the inner peripheral surface 17 of the bore. A cooling oil pipe 19 is inserted into the insertion hole 18, and an end of the cooling oil pipe 19 on the outer peripheral side of the cylinder block 16 communicates with the oil pump side.
The inner peripheral end is inserted through a through hole 20 of a cooling oil pipe formed through the upper part of the outer cylinder 3 of the cylinder liner 1 in a radial direction to enter the first annular groove group 6A of the inner cylinder 2 of the cylinder liner 1. Facing the vertical groove 7. An O-ring groove 21 is formed on the outer peripheral surface of the cooling oil pipe 19 at a portion facing the inner peripheral surface of the cooling oil pipe insertion hole 20 of the outer cylinder 3, and an O-ring 22 is mounted in the groove 21. Cylinder block 1
6 also has a portion facing the inner peripheral surface of the cooling oil pipe insertion hole 18.
A ring groove 23 is formed, and an O-ring 24 is mounted in the groove 23. The cooling oil flowing through the outer peripheral groove of the inner cylinder 2 of the cylinder liner 1 and the cooling water flowing through the outer peripheral groove of the outer cylinder 3 described below. Seal between the two.

The flow of the cooling oil flowing on the outer periphery of the inner cylinder 2 will be described below.
9, the cooling oil flowing into the vertical groove 7 forming the entrance of the first annular groove group 6A of the inner cylinder 2 flows through the annular groove 6 of the first annular groove group 6A to the opposite side by 180 degrees. Then, the gas flows from the vertical groove 8 forming the outlet of the first annular groove group 6A to the vertical groove 9 forming the entrance of the second annular groove group 6B.

Then, the annular groove 6 of the second annular groove group 6B is
It flows toward the opposite side by 80 degrees, and flows from the longitudinal groove 10 forming the outlet of the second annular groove group 6B to the longitudinal groove 11 forming the inlet of the third annular groove group 6C.

Then, the annular groove 6 of the third annular groove group 6C is
It flows toward the opposite side by 80 degrees, enters the longitudinal groove 12 forming the outlet of the third annular groove group 6C, enters the continuous longitudinal groove 15 for discharge, and passes therethrough. After falling, it flows down to an oil pan (not shown).

The flow of the cooling oil is as follows: oil pan → oil pump → oil filter → cylinder block 16 → outer circumference of the inner cylinder 2 of the cylinder liner 1 → oil pan, but other flows are also possible. .

In the above case, three annular groove groups 6A, 6B,
The total cross-sectional area of the annular groove 6 in 6C decreases toward the top, and the flow rate of the cooling oil flowing through each of the annular groove groups 6A, 6B, 6C increases as the upper annular groove group increases. Therefore, the heat transfer coefficient of the cooling oil increases as it goes to the upper part of the liner, the cooling capacity increases, and appropriate oil cooling corresponding to the temperature gradient in the liner axial direction is performed.

Although three annular groove groups have been described above, two or four or more annular groove groups may be used.

Further, it is also possible to provide a discharge path in the cylinder block without providing the vertical groove 15 for discharging the cooling oil to the oil pan, and to allow the cooling oil to flow out into the discharge path. Good.

Next, the structure of the outer cylinder 3 will be described with reference to FIGS. 1, 2 and 4. FIG. The outer cylinder 3 has a flange portion 34 at the upper end, and eight annular grooves 36 are formed on the outer peripheral surface 35 of the liner below the flange portion 34 at intervals in the axial direction. And
These annular grooves 36 are divided into two annular groove groups.

The two annular groove groups include a first annular groove group 36A from the first annular groove 36 to the third annular groove 36 on the upper end side of the liner, and a fourth annular groove 36 to the eighth annular groove 36. And a second annular groove group 36B up to the annular groove 36.

In the first annular groove group 36A, two vertical grooves 37 and 38 for connecting the annular grooves 36 to each other are formed at two positions separated by 180 degrees in the liner circumferential direction. The directional groove 37 forms the inlet for the coolant, and the other longitudinal groove 38 forms the outlet for the coolant.

Similarly, in the second annular groove group 36B, two longitudinal grooves 37 which communicate the annular grooves 36 at two positions circumferentially identical to the longitudinal grooves 37 and 38 of the first annular groove group 36A. Grooves 39 and 40 are formed, and a vertical groove 39 located on the coolant outlet side of the first annular groove group 36A serves as a coolant inlet, and the other vertical groove 40 serves as a coolant outlet.

The vertical grooves 37 forming the inlet of the cooling liquid of the first annular groove group 36A and the vertical grooves 40 forming the outlet of the cooling liquid of the second annular groove group 36B are formed by these vertical grooves 3.
7, 40 are connected in series by a longitudinal groove 41 provided at the same position in the circumferential direction.

The outer cylinder 3 is fitted into the bore of the cylinder block 16 and the flange 34 of the outer cylinder 3 is
6 is placed on a step 28 provided on the inner periphery of the upper end of the bore. As described above, the inner cylinder 2 is inserted into the outer cylinder 3, and the flange 4 of the inner cylinder 2 is placed on the step 31 provided on the inner periphery of the flange 34 of the outer cylinder 3. . And outer cylinder 3
A space defined by the grooves 36 to 41 formed on the outer peripheral surface 35 of the cylinder block 16 and the inner peripheral surface 17 of the bore of the cylinder block 16 forms the cooling water passage 32.

The cylinder block 16 is located at a position 180 degrees apart from the insertion hole 18 of the cooling oil pipe in the circumferential direction.
Two cooling water holes 25 and 26 are formed. The cooling water hole 25 formed in the lower part of the cylinder block 16 serves as a cooling water inlet, one end of which is opened to the outer periphery of the cylinder block 16 and communicates with the water pump side, and the other end of the second annular groove group 36B. The cooling water is communicated with a vertical groove 39 serving as an inlet. The cooling water hole 26 formed in the upper part of the cylinder block 16 forms an outlet of the cooling water, one end is opened on the upper surface of the cylinder block 16 and communicates with the cylinder head side, and the other end is formed in the first annular groove group 36A. It communicates with a longitudinal groove 38 forming an outlet. An O-ring groove 42 is formed in the outer peripheral surface 35 of the outer cylinder 3 of the cylinder liner 1 at a position lower than the lower cooling water hole 25 formed in the cylinder block 16, and an O-ring 43 is mounted.

The flow of the cooling water flowing around the outer cylinder 3 will be described below. The cooling water flows through a cooling water hole 25 provided in the cylinder block 16 and forms an inlet of the second annular groove group 36 B of the outer cylinder 3. The cooling water that has flowed into the vertical groove 39 flows through the annular groove 36 of the second annular groove group 36B to the opposite side by 180 degrees, and from the vertical groove 40 that forms the outlet of the second annular groove group 36B to the first. It flows into the longitudinal groove 37 which forms the entrance of the annular groove group 36A.

Then, the annular groove 36 of the first annular groove group 36A
Through the first annular groove group 36
A from the vertical groove 38 forming the outlet of the cylinder block 1
6 and flow toward the cylinder head side.

The flow of the cooling water is as follows: radiator → water pump → cylinder block 16 → cylinder liner 1
, The outer circumference of the outer cylinder 3 → the cylinder head → the radiator, but other flow methods are also possible.

In the above case, the two annular groove groups 36A, 36
The total cross-sectional area of the annular groove 36 in B becomes smaller toward the upper part, and the flow rate of the cooling water flowing through each of the annular groove groups 36A and 36B becomes larger toward the upper annular groove group. Therefore, the heat transfer coefficient of the cooling water increases as it goes to the upper part of the liner, the cooling capacity increases, and the upper part of the liner is cooled better,
Appropriate water cooling corresponding to the temperature gradient in the liner axis direction is performed.

In the above description, an example of two annular groove groups is shown, but three or more annular groove groups may be used.

In the above embodiment, the cross section of the groove is rectangular, but there is no particular limitation, and the groove may be V-shaped or semi-circular. However, in order to increase the heat transfer area, a rectangle or square is preferred.

Further, if the flow of the cooling water on the outside is stopped during the warm-up operation, the warm-up operation time can be further reduced.

It is needless to say that the configuration of the coolant groove in the inner cylinder and the outer cylinder of the cylinder liner is not limited to the above-mentioned groove configuration, and other annular groove and vertical groove configurations such as the outer peripheral surface of the cylinder liner A plurality of annular grooves are formed, and a vertical groove connecting these adjacent annular grooves to each other is formed. The vertical groove is provided one in the circumferential direction and is separated by 180 degrees along the axial direction. It may be arranged alternately at a position. Furthermore, a spiral groove may be used.

In the above description, the cooling oil groove is formed on the outer peripheral surface 5 of the inner cylinder 2 of the cylinder liner 1 and the inner peripheral surface 3 of the outer cylinder 3 is formed.
Although the cooling oil passage 29 is formed between 0 and 0, a cooling oil groove may be formed on the inner peripheral surface of the outer cylinder, and a cooling oil passage may be formed between this and the outer peripheral surface of the inner cylinder. . Further, cooling oil grooves may be formed on both the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder.

The cooling water groove is formed on the outer peripheral surface 35 of the outer cylinder 3 of the cylinder liner 1 and the cooling water passage 32 is formed between the outer peripheral surface 35 and the inner peripheral surface 17 of the bore of the cylinder block 16. A cooling water groove may be formed on the inner peripheral surface of the portion, and a cooling water passage may be formed between the cooling water groove and the outer peripheral surface of the outer cylinder. Further, cooling water grooves may be formed on both the outer peripheral surface of the outer cylinder and the inner peripheral surface of the bore of the cylinder block.

[0044]

As described above, according to the cylinder liner cooling structure of the present invention, the cooling oil and the cooling water are excellent in the warm-up characteristics and the cooling performance at the time of high-speed operation. And there is no need for a large oil cooler.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is an enlarged detail view of a portion Z in FIG. 1;

FIG. 3 is a development view showing a part of an outer peripheral surface of an inner cylinder of the cylinder liner.

FIG. 4 is a development view showing a part of an outer peripheral surface of an outer cylinder of the cylinder liner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylinder liner 2 Inner cylinder 3 Outer cylinder 4, 34 Flange part 5, 35 Outer peripheral surface 6, 36 Annular groove 6A, 36A First annular groove group 6B, 36B Second annular groove group 6C Third annular groove group 7, 8, 9, 10, 11, 12, 13, 14, 15 Vertical groove 37, 38, 39, 40, 41 Vertical groove 16 Cylinder block 17 Bore inner peripheral surface 18, 20 Cooling oil pipe insertion hole 19 Cooling oil pipe 21, 23, 42 O-ring groove 22, 24, 43 O-ring 25, 26 Cooling water hole 28, 31 Stepped portion 29 Cooling oil passage 30 Outer cylinder inner peripheral surface 32 Cooling water passage T Thrust position AT Anti-thrust position F Front position R Rear position

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02F 1/16 F01P 3/02

Claims (1)

(57) [Claims] 1. A cylinder liner inserted into a bore of a cylinder block has a double cylinder structure of an inner cylinder and an outer cylinder, and is provided on one or both of an outer peripheral surface of an inner cylinder and an inner peripheral surface of an outer cylinder of the cylinder liner. A groove for a cooling oil passage is formed, and a groove for a cooling water passage is formed on one or both of an outer peripheral surface of the outer cylinder and an inner peripheral surface of a bore portion of the cylinder block. Cooling structure.