Cast Inflow And Outflow Openings For Cast-Steel And Cast Iron Pistons

Abstract

Method for producing a piston having a cooling channel produced by a lost core casting process. A lost core extends into a casting mold which forms the inner region of the piston blank. The lost core is used to form at least one opening having a rounded profile in communication with the cooling channel. A jet splitter may be formed in the cooling duct to divert injected cooling oil into the cooling duct.

Claims

1. A method for producing a piston which has a cooling duct that is generated by way of a lost core, wherein a piston blank is cast in a casting method using a casting melt and using a casting mold into which the core is inserted prior to casting, and the piston blank is removed from the casting mold after the solidification of the casting melt and the core subsequently is flushed out, and final processing of the piston blank is thereafter performed in order for the piston to be generated, characterized in that the core extends into a region of the casting mold that configures an inner region of the piston blank, and at least one opening that has a rounded profile for the cooling duct is formed by way of the core after flushing.

2. The method of claim 1, further comprising forming at least one inflow opening having an encircling bead by means of the core, the at least one inflow opening in communication with the cooling duct.

3. The method of claim 1, further comprising forming at least one outflow opening having an encircling bead by means of the core, the at least one outflow opening in communication with the cooling duct.

4. The method of claim 2, further comprising forming a jet splitter by means of the core at least in the region of the inflow opening.

5. The method of claim 4 wherein the jet splitter is positioned in the cooling duct.

6. The method of claim 3 further comprising forming a jet splitter by means of the core at least in the region of the inflow opening.

7. A method for forming a piston blank comprising: inserting a casting lost core into a casting mold having a cavity, the lost core defining an inner region of the piston blank; extending a rounded portion of the lost core into the mold cavity defining a piston blank cooling duct and at least one cooling oil opening in communication with the cooling duct; adding a casting melt into the casting mold cavity including the lost core forming the piston blank cooling duct and at least one cooling oil opening; cooling the casting melt to solid form forming the piston blank; removing the piston blank from the casting mold; and flushing the lost core from the piston blank.

8. The method of claim 7 wherein the at least one cooling oil opening comprises an inflow opening.

9. The method of claim 8 wherein the at least one cooling oil opening further comprises an outflow opening.

10. The method of claim 8 further comprising forming by the lost core a jet splitter in the cooling duct axially adjacent the inflow opening, the jet splitter operable to engage and divert cooling oil injected through the at least one cooling oil opening into the cooling duct.

Description

DETAILED DESCRIPTION

[0008] The invention will be described in more detail and be explained by means of the figures hereunder by means of a piston which is produced by the method according to the invention.

[0009] A piston blank 1 which after the production thereof has an external contour referred to by the reference sign 2 is illustrated in FIG. 1. The piston blank 1 is produced by means of a respective casting method using a casting mold, wherein the casting mold has the internal contour of the external contour 2 of the piston blank 1. The casting mold can be designed in one or a plurality of parts. A lost core 3 which in a suitable manner is disposed on the casting mold, for example on the inner insert of the casting mold, is provided as part of the casting mold. It is also conceivable for more than one lost core 3 to be provided. Once the at least one core 3 has been disposed on and fastened to the casting mold, the casting mold is filled with casting melt, time then being spent on waiting until said casting melt has solidified. The casting mold is subsequently removed, wherein the lost core 3 initially remains in the piston blank 1 produced. The latter is flushed out in the usual manner such that an inner region is created in the piston blank 1 on account thereof, said inner region corresponding to the external shape of the core 3 and forming a cooling duct 4. The contour illustrated in FIG. 1 or the profile of the cooling duct 4, respectively, is exemplary and not limited thereto.

[0010] A finished contour, once the piston blank 1 has been further processed, is designated by dashes and referred to by the reference sign 5. This final processing has been performed in particular by chip-removing machining of the external region of the piston blank 1. This final processing is performed either after or optionally prior to flushing out the core 3.

[0011] The completely processed piston finally has elements known per se, such as a ring zone, a bolt bore 6, a piston skirt 7, and further commonplace elements (such as, for example, optionally a combustion bowl).

[0012] A view into an inner region of a finished piston 8 which is based on the piston blank 1 according to FIG. 1 is illustrated in FIG. 2. In the case of this exemplary design it can be seen that, proceeding from the bolt bores 6, connection walls extend in the direction of the load-bearing piston skirts 7. Said connection walls are disposed on the lower side of the upper part of the finished piston 8, wherein at least one inflow opening 9 is also located on said lower side. An encircling bead 10 is disposed around the inflow opening 9 in this exemplary embodiment. The cross section of the inflow opening 9 herein is circular but can deviate from this geometric shape. The same apples also to the encircling bead 10 in this instance.

[0013] When viewed through the inflow opening 9 in the direction of the lower side of the upper part of the piston 8, an optional jet splitter 11 in the cooling duct 4 is also illustrated (more specifically on the apex of the latter, so as to protrude downward in the direction of the inflow opening 9).

[0014] In the case of the piston 8 according to FIG. 2, the injection of cooling oil is performed by way of the (at least one) inflow opening 9 such that the cooling oil can circulate in the cooling duct 4. In order for said cooling oil to be able to exit the cooling duct 4 again, according to FIG. 2 at least one outflow opening 12 which can likewise be provided with an encircling bead 13 (this not being mandatory) is present. According to the invention, the openings 9, 12 (and optionally further openings) are produced by means of the lost core 3, wherein the rounded profile of the opening 9, 12, for example implemented having the encircling bead 10, 13 that serves for reinforcing the respective region, is also produced by means of the lost core which extends into a region of the casting mold that configures an inner region of the piston blank 1.

A List of Drawing Reference Signs is Below.

[0015] 1. Piston blank

[0016] 2. External contour

[0017] 3. Lost core

[0018] 4. Cooling duct

[0019] 5. Finished contour

[0020] 6. Bolt bore

[0021] 7. Piston skirt

[0022] 8. Finished piston

[0023] 9. Inflow opening

[0024] 10. Encircling bead

[0025] 11. Jet splitter

[0026] 12. Outflow opening

[0027] 13. Encircling bead