GB2070732A - Cylinder liner - Google Patents

Abstract

A cylinder liner is formed with a spiral groove 22, 33a, 33b on at least part of its cylindrical outer surface for firm engagement to the cylinder block. <IMAGE>

Description

SPECIFICATION Cylinder block structure with cylinder liner The present invention relates to a cylinder block structure with cylinder liners wherein each cylinder liner is firmly engaged with the cylinder block surrounding the cylinder liner Cylinder liners must withstand the sliding of a piston for a long time and must be excellent in wear-resistivity and in heat-conductivity so as to efficiently dissipate the combustion heat.

Accordingly, where a cylinder block is formed from an aluminium alloy material, cyl inder liners within the cylinder block are usu ally formed of a different material which is excellent in wear-resistivity and in heat-reisis tivity.

Referring to a conventional cylinder liner, as shown in Fig. 1, upon casting a cylinder block 2 the material for the cylinder block 2 is cast around the cylinder liners 1.

It is necessary that the cylinder sinews 1 firmly engage the cylinder block 2 so as to prevent rotation of each liner 1 during ma chining such as boring or honing, and to prevent axial movement of the liner 1 owing to a sliding resistance of a piston 3 during operation.

It is also necessary to secure a sealable contact of each liner main body 1 with the block 2 because an inadequate sealable con tact may cause a lack of cooling of the liner main body although the liner main body 1 is disposed adjacent a coolant passage 4 through the block 2.

To deal with these demands, the conven tional cylinder liner is formed with an end flange 5 at one axial end thereof, as shown in Fig. 2, thereby preventing axial movement, and additionally, vertical grooves 6 are formed in the side surface of the flange at equi-distant circWumliFerentiai intervals, thereby preventing rotation of the cylinder liner.

However, with this kind of cylinder liner, although the upper axial end portion of the liner msiii body 1 engages firmly with the cylinder block 2, it is quite difficult to secure firm enÇ3a,gerilan-t 0-6 the middle portion and lower axias ond portion of the liner with the cylinder block 2. Hence, a tight sealing con iai:t of the linor with the cylinder block is not possible.

Besides. tiisre ,s also a shortcoming in that formincç4 of the liner main body 1 is compli- cated because the flange 5 and the axial grooves 6 are frjrmed in different working steps.

According to the present invention, in order to effecx firnl engagement of a cylinder liner with a cylinder block, the cylinder liner has a spiral groove on its outer surface, whereby rotation and axial movement of the liner dur ing machining a cylinder bore and during sliding operation of a piston in the cylinder bore are prevented.

In the accompanying drawings:- Figure 1 is a vertical sectional view showing a conventional cylinder liner embedded in a cylinder block; Figure 2 is a perspective view of the conventional liner shown in Fig. 1; Figure 3 is an enlarged perspective view of a first embodiment of a cylinder liner according to the present invention; Figure 4 is a side elavational view, partly sectioned, of the liner shown in Fig. 3; Figure 5 is an enlarged perspective view of a second embodiment of a cylinder liner according to the present invention; and Figure 6 is a side elevational view, partly sectioned, of the liner shown in Fig. 5.

Hereinafter, two embodiments according to the present invention are explained with reference to the drawings.

As shown in Figs. 3 and 4, a cylindrical liner main body 21 has a spiral groove 22 formed on an outer peripheral surface thereof and extending in an axial direction.

The width, depth, pitch, etc. of the groove 22 are appropriately selected in accordance with the dimension of the liner main body 21 such that the liner main body 21 is prevented from rotation and axial slip during boring and honing of the inner peripheral surface of the liner, or during engine operation after the casting of the block is completed. This permits, during casting, the molten material to flow evenly to improve the seal tightness between the liner main body 21 and the block 2 after the completion of casting, thus strengthening the bond therebetween.

With this structure, since the cylinder liner main body 21 is securely and fixedly bonded to the cylinder block, there occur no loss or waste during boring or honing and the inner surface of the liner main body 21 is finished smoothly.

Because the spiral groove is formed by rolling, the number of production steps has been decreased, thus resulting in a cost reduction.

Further, osciliatory axial movement of the liner main body 1 or movement thereof from the block during piston sliding is prevented.

Next, reference is made to another embodiment illustrnted in Figs. 5 and 6.

In this embodiment, a liner main body 31 has on an outer peripheral surface thereof an annular recessed section defining an upper flange 32a and a lower flange 32b, each formed with respective spiral grooves 33a, 33b with different pitches, so as to increase the effectiveness in preventing rotation.

Although, not illustrated, the upper spiral groove 33a may be oriented in the opposite direction to that of the lower spiral groove 33b.

As having been described, according to the present invention, a cylinder liner main body has on an outer peripheral surface thereof a spiral groove having a predetermined pitch, width, and depth so as to fixedly bond the liner to the block during casting, the rotation of the liner during machining of the cylinder bore and reciprocal vertical movement of the liner during piston sliding being prevented with a very simple and inexpensive means.

Beside, a good sealing tight connection between the liner and block is provided, thus eliminating the inconvenience of inadequate cooling.

Claims (5)

1. A cylinder liner for a cylinder block comprising: a main body having a spiral groove formed on a cylindrical outer surface thereof.

2. A cylinder liner as claimed in claim 1, including an annular recessed section defining first and second annular flanges at respective axial ends thereof.

3. A cylinder liner as claimed in claim 2, including a second spiral groove in said second annular flange oriented in the opposite direction to that of said first spiral groove formed on said first annular flange.

4. A cylinder block structure incorporating a cylinder liner comprising a main body having a spiral groove formed on a cylindrical outer surface thereof, said structure including a cylinder block surrounding said cylindrical outer surface of said main body of the cylinder liner to firmly engage the cylinder liner.

5. A cylinder liner substantially as described with reference to, and as illustrated in, Figs. 3 and 4, or Figs. 5 and 6, of the accompanying drawings.