JPH0378518A - Cooling structure for engine - Google Patents

Abstract

PURPOSE:To eliminate cooling nonuniformity of a liner outer wall surface, in a longitudinal passage communicating respectively to multiple circumferential grooves arranged on an outer wall surface of the liner, by gradually increasing and decreasing a cross sectional area thereof toward a downstream side at upper and lower half parts respectively. CONSTITUTION:Multiple circumferential grooves 30 for circulating liquid coolant are arranged on the outer wall surface of a liner 16 fitted inside a cylinder bore part of a crank case 12. Each circumferential groove 30 is divided into a plurality of groove groups I, II, and is communicating to a longitudinal passage 32c which is formed on the outer wall surface of the liner 16. In this occasion, a lateral width of the passage 32c is gradually increased from an upper stream side toward a downstream side, at an upper half part where the liquid coolant flows from the circumferential groove 30 of the groove group I into the longitudinal passage 32c. On the other hand, at a lower half part where lubricating oil flows from the longitudinal passage 32c into the circumferential groove 30 of the other groove group II, the lateral width of the passage 32c is gradually decreased from the upper steam side toward the downsteam side.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an engine cooling structure.

(Prior Art) In an engine equipped with a wet liner such as a vehicle diesel engine, a large number of circumferential grooves are provided at intervals in the axial direction on the outer wall surface of the liner, and each of the circumferential grooves is provided with several grooves. The circumferential groove of each groove group is communicated with a passage formed in the outer wall surface of the liner in the vertical direction, that is, in the direction of the cylinder axis, and sequentially from the groove group on the upstream side via the longitudinal passage. A cooling structure has already been proposed in which a cooling liquid is caused to flow through a group of grooves on the downstream side.

In this type of engine cooling structure, circumferential grooves are arranged relatively densely on the outer wall surface of the liner, and cooling liquids such as lubricating oil and cooling water are forced to flow through these circumferential grooves. It is possible to effectively cool the liner which is exposed to severe heat loads such as high power supply and output, and at the same time it is possible to simplify the structure and reduce the weight of the crankcase that holds the liner.

Now, with reference to FIGS. 1 and 3 showing an embodiment of the present invention, and with reference to FIG. 4, a typical configuration of a conventional engine cooling structure of this type will be described.

First, in FIG. 1, reference numeral 10 generally indicates a direct injection diesel engine for trucks.

12 is a crankcase of the engine, 14 is a cylinder head, 16 is a cylinder liner fitted in a bore 18 formed in the crankcase 12, and 20 is a piston fitted in the liner 16.

22 is the connecting rod, 24 is the crankcase 1
An inlet oil gear lary 26 is formed within the crankcase 12 and extends in the crank axial direction; 26 is an outlet oil gear lary formed within the crankcase 12 extending in the crank axial direction; and 28 is an outlet oil gear lary mounted on the cylinder head 14. This is a fuel injection nozzle.

A large number of circumferential grooves 30 are provided on the outer wall surface of the liner 16 at appropriate intervals in the cylinder axis direction. In the illustrated case, the plurality of circumferential grooves 30 are arranged in the cylinder head 1.
Groove group 1. includes several circumferential grooves 30, for example, four circumferential grooves 30, sequentially from the fourth side. It is grouped into It and ■. As clearly shown in the schematic diagram of FIG. The circumferential groove 30 shown in (2) is connected to the outlet side gear rally 26 by a vertical passage 32b formed on the outer wall surface of the liner on the opposite side in the diametrical direction to the passage 32a. Further, the groove groups I and (2) are connected by a vertical passage 32e formed on the outer wall surface of the liner diametrically opposite to the passage 32a,
On the other hand, the groove groups 1 and 2 are connected by a vertical passage 32d formed on the outer wall surface of the liner on the extension line of the passage 32a. (In the schematic diagram of FIG. 3, each circumferential groove 30 is represented by one inner half shown by a solid line and the other half inner part shown by a chain line.) Inlet side oil gear The lubricating oil as a cooling liquid supplied from 24 flows through each circumferential groove 30 of the groove group (2) from the vertical passage 32&, and enters the passage 32c.

From the passage 32c, it flows through each of the circumferential grooves 30 of the groove group (■) and flows out to the passage 32d, and further flows from the same passage 32d through each of the circumferential grooves 30 of the groove group (2), flows out to the passage 32b, and finally exits. The oil flows into the side oil gear gallery 26.

- In a conventional configuration, as shown in FIG.

The longitudinal passage 32c that guides the lubricating oil from the circumferential groove 30 of groove group I to the circumferential groove 30 of groove group The same applies to the vertical passage 32d that guides the lubricating oil from the circumferential groove 30 of the groove group (2) to the circumferential groove 30 of the groove group (m). A plurality of (four in the illustrated case) circumferential grooves 30 of groove group I to the longitudinal passage 3
When lubricating oil flows into 2c, the number of circumferential grooves 30 gradually increases from the upstream side to the downstream side, so the lubricating oil in the plurality of circumferential grooves 30 is collected by the vertical passage 32e with a −-like cross-sectional area. In this case, the lubricating oil flow velocity in each circumferential groove becomes uneven, and the circumferential groove 30 with a high flow velocity has a large cooling capacity, and the circumferential groove 30 with a low flow velocity has a small cooling capacity, so it belongs to the same groove group. Cooling unevenness occurs in the cylinder axial direction in the liner wall portion with the circumferential groove fitting. This is exactly the same when the lubricating oil flows from the same vertical passage 32c into the groove group (2) in the downstream portion thereof, and the same is obviously true for the vertical passage 32d as well.

(Problem to be solved by the invention) The present invention was created in view of the above circumstances.

By making the flow velocity of cooling liquid such as lubricating oil approximately equal in the circumferential grooves of each groove group divided into multiple groove groups, which are arranged in multiple stages on the outer wall surface of the liner, the circumferential grooves belonging to the same groove group are Eliminates as much as possible uneven cooling in the cylinder axial direction of the grooved liner wall, prevents the cooling performance from deteriorating due to uneven cooling, and effectively reduces thermal strain and thermal stress. The purpose is to It is something.

(Means for Solving the Problems) In order to achieve the above object, the engine cooling structure according to the present invention includes a liner fitted into the cylinder bore of the crankcase, and a large number of cooling fluids flowing through the outer wall surface of the liner. providing a circumferential groove, dividing the circumferential groove into a plurality of groove groups each including a plurality of grooves, and communicating the circumferential groove of each groove group with a vertical passage formed in the outer wall surface of the liner; The cooling liquid is configured to flow from the groove group on the upstream side to the groove group on the downstream side sequentially through the same longitudinal passage, wherein the cooling liquid flows into the vertical groove from the plurality of circumferential grooves in the groove group. The directional passage is formed so that the cross-sectional area increases from the upstream side to the downstream side, and the longitudinal passage in which the cooling liquid flows from the longitudinal passage to the plurality of circumferential grooves in the groove group is formed so that the cross-sectional area increases from the upstream side to the downstream side. It is characterized by being formed so that the cross-sectional area decreases toward the sides.

(Function) According to the present invention, the longitudinal passage into which the cooling liquid flows from the plurality of circumferential grooves is formed so that the cross-sectional area increases from the upstream side to the downstream side. The vertical passages that distribute the cooling liquid are formed so that the cross-sectional area decreases from the upstream side to the downstream side, so that the flow velocity of the cooling liquid flowing through the plurality of circumferential grooves in each groove group is equalized. became
The occurrence of uneven cooling of the liner wall portion provided with the circumferential grooves belonging to each groove group is effectively prevented.

(Example) Examples of the present invention will be specifically described below with reference to FIGS. 1 and 2. (It should be noted that the same reference numerals are given to members or parts that are substantially the same as or correspond to the conventional configuration explained with reference to FIGS. 1 and 3 and with reference to FIG. ) According to the present invention, as shown in particular in FIG. In this case, the width of the passage 32c in the lateral direction, that is, the width in the direction perpendicular to the cylinder axis increases sequentially from the upstream side to the downstream side,
In other words, the cross-sectional area is formed to increase sequentially. Further, the circumferential groove 3 belonging to the groove group
In the lower half portion where the lubricating oil flows into the passage 32e, the width in the lateral direction, that is, the cross-sectional area of the passage 32e is formed so as to decrease sequentially from the upstream side to the downstream side. Therefore, compared to the previous configuration shown in FIG. 4, the circumferential grooves 3 belonging to groove groups I and
It is possible to equalize the flow velocity of lubricating oil in the liner 0, reduce uneven cooling of the liner wall portion provided with each groove group ① and ②, improve cooling efficiency, and reduce the occurrence of thermal distortion and thermal stress. .

Furthermore, the configuration shown in FIG. 2 can be applied as is to the vertical passage 32d that guides the lubricating oil flowing through the circumferential grooves 30 of groove group (2) to the circumferential grooves 3o of groove group (2). Furthermore, if necessary, the vertical passage 32a for supplying lubricating oil from the inlet side oil gear lary 24 to the circumferential groove 30 of groove group I may be provided with a structure similar to the lower half of the passage 32e shown in FIG. Further, the structure of the upper half of the passage 32c shown in FIG. 2 can be adopted for the vertical passage 32b that guides the lubricating oil flowing out from the circumferential groove 30 of the groove group (1) to the outlet side oil gear rally 26.

Note that the change in the cross-sectional area of the vertical passages 32 & to 32d described above is as shown in FIG. It is preferable to achieve this mainly by changing the width of the passage, but if there is no practical problem, the desired passage cut-off can be achieved by changing the depth of the passage or by changing both the depth and the width. A change in area can be realized.

Furthermore, the thermal load on the liner 16 is, needless to say, severe in the upper part near the cylinder head 14 and relatively low in the lower part on the crankshaft side. The longitudinal passages in the lower half of the liner may optionally be of uniform cross-sectional area as is conventional, with only the variation in passage cross-sectional area as described above.

Furthermore, in the illustrated embodiment, the plurality of circumferential grooves 30 are divided into three groove groups 1. Although it is divided into I and ■, it goes without saying that it may be divided into two groove groups, or may be divided into four or more groove groups. In addition, in the illustrated embodiment, ° represents each groove group l, ■, and ■.
each has four circumferential grooves 30, but three or five circumferential grooves 30 are provided.
The number of circumferential grooves 30 included in each groove group does not have to be equal.Furthermore, the cooling liquid is not limited to lubricating oil, and other cooling liquids such as cold water can be used. The lubricating oil that has flowed in the circumferential groove 30 and cooled the liner 16 is
As shown in the figure, it is of course possible to directly flow down into the oil sensor from the lower end portion of the outer periphery of the liner 16 without storing it in the outlet side oil gear gallery 26.

(Effects of the Invention) As described above, the engine cooling structure according to the present invention includes a liner fitted into the cylinder bore of the crankcase, and a large number of circumferential grooves for circulating cooling fluid on the outer wall surface of the liner. At the same time, the circumferential groove is divided into a plurality of groove groups including a plurality of grooves, and the circumferential groove of each groove group is communicated with a vertical passage formed on the outer wall surface of the liner. The cooling liquid is configured to flow sequentially from the upstream groove group to the downstream groove group through The longitudinal passage is formed so that its cross-sectional area increases from the side to the downstream side, and the cooling liquid flows from the longitudinal passage into the plurality of circumferential grooves in the groove group from the upstream side to the downstream side. It is characterized by being formed to have a reduced cross-sectional area, and improves the cooling efficiency by eliminating or at least reducing the uneven cooling of the liner wall portion provided with the circumferential grooves belonging to the groove group. Fig. 2 is an enlarged front view of the longitudinal passage 32c portion in Fig. 1, and Fig. 3 is an enlarged front view of the longitudinal passage 32c in Fig. 1. FIG. 4 is an enlarged front view similar to FIG. 2 showing the conventional structure.

10...Engine, 12...Crankcase, 14
...Cylinder head, 16...Liner, 20...
Piston, 30...Circumferential groove, 32a to 32d...
Vertical passage O

Claims (1)

[Claims] Fit the liner into the cylinder bore of the crankcase,
A large number of circumferential grooves are provided on the outer wall surface of the liner for circulating the cooling fluid, and the circumferential grooves are divided into a plurality of groove groups each including a plurality of grooves, and the circumferential grooves of each groove group are divided into the circumferential grooves of the liner. The cooling liquid is communicated with a vertical passage formed on the outer wall surface and is configured to flow sequentially from an upstream groove group to a downstream groove group via the longitudinal passage, wherein The longitudinal passage into which the cooling liquid flows from the plurality of circumferential grooves is formed so that the cross-sectional area increases from the upstream side to the downstream side, and the cooling liquid flows from the longitudinal passage into the plurality of circumferential grooves in the groove group. An engine cooling structure characterized in that the longitudinal passage into which liquid flows is formed so that its cross-sectional area decreases from the upstream side to the downstream side.