EP0974414B1 - Casting mould and a casting process for the production of an engine block - Google Patents

Abstract

The engine block has structured cooling channels in the walls between the cylinders with a reduced cross section where the channel axis intersects the cylinder axes. The cast engine block has a cooling channel in the intermediate cylinder wall with a minimum cast wall thickness of less than or equal to 5 mm. The cooling channel is wholly defined by a skin of the cast material. The cross section surface of the cooling channel is reduced from its end to a cross section surface of the cooling channel axis (14) where it intersects the cylinder axis. The minimum width of the cooling channel at the cross section surface axis at the intersection with the cylinder axis is 0.5-1.5 mm. The mold has channel molding cores (8) at the ends of the cores (2,3) to give the cylinder openings.

Description

The invention relates to a casting mold for the production an engine block, which is a between Cylinder recesses extending a cylinder row Cooling channel, wherein between the cylinder recesses a minimum Gußmaterialwanddicke of less than 5 mm is provided, wherein in the mold to form the Cooling channel between the cylinder recesses forming Cores of the mold only at its ends held channel shaped core is arranged.In addition The invention relates to a method for producing a Engine block with at least one cooling channel in one Intermediate wall between adjacent cylinder recesses, wherein the wall thickness formed by casting material less than 5 mm, the engine block by pouring of Casting material is imaged in a mold and wherein in the mold the cores forming the cylinder recesses be inserted.

To keep the length of a e.g. cast aluminum To keep engine blocks as low as possible, one endeavors the cylinder recesses of a cylinder bank close together to arrange, resulting in correspondingly thin Cylinder partitions result. By the narrower adjacent combustion chambers and the diminished Heat dissipation are subject to these dilute partitions, in particular to the cylinder head end facing the Cylinder surface, an increased thermal load, which makes it necessary in the partition one Provide cooling duct.

It is known to cut a cooling channel by cutting Processing by the fact that of the Cylinder head contact surface of the engine block forth in the Engine block cut in and the incision again is closed, leaving a cooling channel, which is extending on opposite sides of the cylinder bank Cooling jacket sections of a cylinder row surrounding Cooling jacket connects. Alternatively, the engine block is for Forming of such a cooling channel drilled laterally, after which it is necessary to drill the passage between the Cooling jacket and the engine block outside again close.

In addition to the above-described prior art from EP 0 197 365 A2 a device and a method for the casting production of a tight-fitting Cylinder blocks are known in which cooling jackets around in the cast engine block arranged cylinder bores are provided by the cooling channels between the Cylinder partitions are connected. The cooling channels are represented by separate cores in the mold, which in an embodiment at its two ends in the Mantelkern are fitted. As material for the channel cores is proposed in EP 0 197 365 A2 zirconsand, because This sand has a high bulk density and therefore a large one Has strength. In practice, however, it turns out that it in small cross sections of the channel core in consequence of at the production of foundry cores unavoidably occurring Strains to a fraction of the channel casting core comes.

Finally, from US 5 217 059 A also still a Casting core and a method for forming a Water jacket chamber inside a cast cylinder block known. It is provided by one of a suitable refractory produced plate between two cylinder chambers form a cooling channel.

The present invention is based on the object, a Mold to create, on the one hand, the production of tight building engines without the use of sand cores themselves enabling restrictions and, on the other hand ensures high productivity during production. In addition, a procedure should be created that with reduced manufacturing costs the production of in their Quality improved engine blocks allows.

This task is related to the mold of the beginning specified type solved in that the channel mold core Glass is made. Regarding the procedure of initially mentioned type, this object is achieved by that in the mold to form the cooling channel between the the cylinder recesses forming cores made of glass existing channel mold core is arranged so that it only on his ends are held.

The casting mold according to the invention makes it possible to use a To produce an engine block in which the strength and Service life compared to a known such engine block is increased by the fact that not to form the cooling channel by machining in the solidification structure of Casting material has been intervened.

In this case, the cross-sectional area of the cooling channel of its ends to a cylinder axis perpendicular crossing Reduce the transverse axis of the cooling channel. With this reduction becomes the decrease of the cylinder intermediate wall to this axis taken into account. With to both sides increasing intermediate wall thickness also increases the Cross-sectional area of the cooling channel, which is advantageous the flow resistance of the channel decreases and the Coolant flow rate increased.

The minimum width of the cooling channel in the direction of the Cylinder axes perpendicular crossing channel transverse axis can between 0.5 and 1.5 mm.

While any cross-sectional surface shapes are conceivable, the channel cross-sectional area is preferably elongate formed and extends parallel to a longitudinal axis to the cylinder axes. While the latitude of the Cooling channel by the strength of the cylinder intermediate wall is limited, the cooling channel in the direction of Cylinder axes increasing the passage cross section to stretch relatively far.

In this case, the cooling channel can be straight between each other opposite sections of a cylinder bank extend surrounding cooling jacket.

Basically, it is conceivable that a Gießformkern from a Soluble in a liquid combustible and / or brittle Material consists, in particular a salt or carbon.

A salt core can be left after the casting and solidification of the Remove casting material from the casting by removing it. It is understood that a soluble salt with a Melting point must be selected, which is above the temperature the casting material used is. Leave a carbon core burn out, including, where appropriate, to promote the Combustion oxygen is supplied. It is further conceivable to use a pyrotechnic core material that besides carbon, one added to the carbon Includes oxidizing agent, wherein by the Material composition complete burnout of the Kern's secured, however, an explosive combustion can be avoided.

An inventively used brittle glass core can be from a narrow cooling channel, even if the cooling channel inputs not accessible by tools, remove by removing e.g. by ultrasound effect into small pieces smashed, the glass core for this purpose by education can be pretreated by voltages accordingly. Alternatively, the glass core can be pressurized standing water jet to be removed.

In a further preferred embodiment of the invention is the mold core at one end at one of the cores for the formation of the cylinder having casting mold part supported. By this measure can be with low Tolerance deviations ensure that the cooling channel based on the cores forming the cylinder recesses and thus based on the cylinder recesses within the Intermediate wall is arranged in the intended position. When holding the channel mold core on another Molded part would have due to fluctuations in the fit the mold parts with each other with respect to the positioning the cooling channel larger manufacturing tolerances accepted become.

Fig.1 einen Teil einer erfindungsgemäßen Gießform in einer Draufsicht,

Fig. 2 eine den Gießformteil von Fig 1 enthaltende Querschnittsansicht der genannten Gießform,

Fig. 3 einen Motorblock nach der Erfindung in einer geschnittenen Seitenansicht,

Fig. 4 den Motorblock von Fig. 3 in einer Querschnittsansicht,

Fig. 5 ein weiteres Ausführungsbeispiel für einen erfindungsgemäßen Motorblock mit einem gebogenen Kühlkanal in einer Querschnittsansicht, und

Fig. 6 den Motorblock von Fig. 5 in einer Draufsicht.

The invention will now be explained and described in more detail with reference to embodiments and the accompanying drawings relating to these embodiments. Show it:

1 shows a part of a casting mold according to the invention in a plan view,

FIG. 2 shows a cross-sectional view of said casting mold containing the casting mold part of FIG. 1, FIG.

3 shows a motor block according to the invention in a sectional side view,

4 shows the engine block of FIG. 3 in a cross-sectional view, FIG.

Fig. 5 shows a further embodiment of an engine block according to the invention with a curved cooling channel in a cross-sectional view, and

Fig. 6 shows the engine block of Fig. 5 in a plan view.

By the reference numeral 1 is in Figs. 1 and 2, a mold part with cores 2 and 3 for the Formation of a cylinder recess called.

The mold part 1 further comprises blocks 4 and 5 with a groove 6 and 7, respectively. In the groove 6 and 7 is with its ends a salt core 8 used. Each of the grooves 6, 7 is so long that for the salt core 8 is given in each groove an expansion clearance.

As can be seen in FIG. 2, the blocks form a breakthrough in the cylinder head facing ceiling 11 of the engine block. While fixing the salt core 8 in the grooves 6, 7 adjoin the blocks 4, 5 against another mold part 12, through which a Cylinder surrounding cooling jacket is formed.

At 13, between the cylinder recesses is a cylinder intermediate wall made of cast material formed, whose minimum width indicated by the arrows is.

As is apparent from Fig. 1, takes the initially constant width of the salt core 8 of his Ends on to a cylinder axis perpendicular crossing transverse axis 14 down and reached a width of 1 mm in this axis, while the outer portions of the salt core in The embodiment have a width of 2.5 mm. The mininmale, by casting material formed wall thickness of the cylinder intermediate wall at 13 is inclusive of minimum channel width 2.5 mm. Not shown are in the engine block einzugießende gray cast iron bushings, so that the total web width is 5.5 mm. The salt core 8 has a rectangular in cross section, with the long rectangle side of the cross section extends perpendicular to the cylinder axes and in the embodiment shown 4 mm is.

The salt core 8 is made of NaCl, which has a melting point above the Temperature of the liquid aluminum casting material used to make the engine block lies. Depending on the casting material, other salts and salt mixtures can be used.

The salt core 8 is in the embodiment shown by pressing and then Sintered.

After a casting and solidification process, the salt core by hot water from the Cast out. and there is a cooling jacket sections on both sides of the Cylinder row connecting cooling channel, which only by a continuous Gußmaterialhaut is limited, which gives the thin cylinder intermediate wall high strength. Through the cooling channel is sufficient heat dissipation and thus high heat resistance ensured the engine made from the engine block.

During the casting process, the Salzkem expands, the grooves 6, 7 with their Provide sufficient space for this extension.

Notwithstanding the embodiment shown, the salt core could to its ends with the cooling effect amplified wider than shown.

By attaching the salt core on the trestles 4,5, which are part of the cores 2.3 contained mold part 1 are, it is ensured that the cooling channel in the Intermediate wall at 13 with small tolerance deviations in the desired position Arrange with respect to the cylinder axes. Instead, the core 8 would be on the held the cooling jacket forming mold part 12, the position of the cooling channel subject to greater fluctuations.

When detaching the core 8 from the formed casting can be used to accelerate the Dissolution process hot and possibly pressurized water can be applied.

Reference will now be made to FIGS. 3 and 4.

In Fig. 3 appear a first cylinder recess 15 of an engine block with a lining 16, a first cylinder intermediate wall 17 and a lining 18 of a next Cylinder recess 19.

In Fig. 4, the cylinder recesses 15, 19 appear half each with the cylinder intermediate wall 17 in the middle. In circled sections A and B is in addition the state of Mold shown.

Also visible are an outer wall 20 of the engine block, a cylinder head surface 21, a Water jacket 22 and two studs 23 for attachment of a cylinder head.

In the framed sections A and B of the water jacket 22 forming mandrel is 24 shown. In this molded with two thicker end portions 25 a Graphite plate 26. The graphite plate has a between the thicker end portions 25 a Thickness of about 1.2 mm and a height of about 12 mm. Extends with these dimensions it is centered by the thickness of the cylinder intermediate wall 17, in a height directly under the stud bolts 23.

In Figs. 3 and 4 outside of the circled sections A and B, the graphite plate 26 in Remove the molded block from the mold before casting.

The Grapfitplatte 26 is finally removed by burning out. She is under blowing ignited by oxygen and burns out continuously, if continuous oxygen in the blown through its channel burned out. This can help to speed up done from both sides. Deviating from this embodiment, the Graphite material to be mixed with an oxidizing agent that no such support needy burnout allows.

The water flow in the engine block is with a certain pressure gradient between the one side of the cylinder bank and the other side provided. This will be through the graphite plate 26 flows through channel generated and thus a removal of heat allows.

For other water-bearing, oil-bearing or gas-carrying thin channels in a cylinder block or cylinder head, the method can also be used advantageously, in particular Also for a narrow water flow between the valve holes of a cylinder head.

Reference will now be made to FIGS. 5 and 6. The reference numeral 27 is shown in FIG. 5 and Fig. 6 denotes an engine block formed by casting. The by soft hatching in the Cross-section engine block 27 is made of an aluminum alloy. With the reference number 28 is a mold part for forming a cylinder surrounding the engine block 27 Cooling jacket called. In the engine block 27 cylinder liners 29 are through Encapsulated with casting material. The cylinder liners 29 are seated in the mold with their entire inner surface each on a hollow cylindrical Kokillendorn 30 of the mold on. The casting mold, which is otherwise not shown, is a sand mold.

In Figs. 5 and 6, reference numeral 31 designates a glass core which is located between adjacent ones Cylinder recesses 32 of the engine block 27 of a sand mold part 33rd zuckt to a sand mold part 34. The Sandgießformteile 33, 34 are with the cooling jacket forming sand mold part 28 connected and serve to form openings of the cooling jacket to the cylinder head contact surface of the engine block 1.

The laid in an arc glass core is respectively at its ends in the mold part 33 and 34 embedded.

In the embodiment shown, the glass material has a thermal expansion coefficient which is slightly below 10 ^-6 K ^-1 . The glass transition temperature is 700 ° C. The glass core 31 has a diameter of 1 mm.

Between each of the cylinder recesses 32 of the engine block 27, a core is arranged, as is apparent from Figs. 5 and 6.

During the casting process, the glass core 31 is encapsulated, wherein the glass material with withstanding the pouring associated with temperature stress. A short time after pouring the glass core reaches the temperature of the casting material and thus its maximum thermal expansion during the casting process. The glass core now cools in temperature weight along with the casting material, wherein the casting material due to its higher thermal expansion coefficient shrinks more than the glass core 31. This Shrinkage regularly causes the glass core 31 to shatter. For this, the glass core Be suitably pretreated by quenching, blasting, etching and / or scribing, in particular such that a plurality of easily removable fragments is formed.

In the embodiment shown, the glass core 31 is laid in the bow so that through the to the cylinder head bearing surface formed through openings a flexible impact tool can be introduced, with the help of which in the event that the glass core in the shrinkage is not or only partially broken, a demoulding takes place.

The curved in the embodiment shown Glasaskem could also be straight. To remove the glass core from the casting then comes an ultrasonic treatment or high-pressure jet treatment of the casting.

In the manner described above can be without intervention in the cast structure Produce channels with very smooth inner walls similar to the quality of holes. Advantageous can not accumulate deposits from the coolant in these channels. Without damaging the engine block, such cooling channels could be located between the cylinder recesses Do not make a hole in the engine block.

The above pretreatment, in which the glass core a the glass breakage Shrinking or by subsequent breaking facilitating structure, in particular Tension structure, receives, is expedient.

Salt cores, graphite cores or glass cores may deviate from the one shown Engine block with a cooling channel between the cylinders related examples also on other locations of the engine block are used, e.g. To form channels through which Coolant or oil can be supplied to certain functional parts in the engine.

Claims (4)

1. A casting mould for the manufacture of an engine block having a cooling channel extending between cylinder recesses (15, 19, 32) of a cylinder bank, with a minimum casting material wall thickness between the cylinder recesses of less than 5 mm wherein for the purpose of forming the cooling channel there is arranged inside the casting mould between the cores (2, 3) of the mould that form the cylinder recesses, a channel-forming core (8, 26) which is supported only at its ends, characterised in that the channel-forming core (8, 26) is made of glass.
2. A casting mould according to claim 1 characterised in that the channel-forming core (8) is supported at its ends on a casting mould part (1) which contains the cores (2, 3) for forming the cylinder recess.
3. A casting mould according to any one of the preceding claims characterised in that spaces are provided in the supports (4-7) for the channel-forming core (8) allowing it to expand in the longitudinal direction during casting.
4. A process for the manufacture of an engine block having at least one cooling channel (31) in a dividing wall between adjacent cylinder recesses (32), the wall thickness formed by the casting material being less than 5 mm, wherein the engine block is formed by casting a casting material into a casting mould and wherein cores forming the cylinder recesses are placed inside the casting mould, characterised in that for the purpose of forming the cooling channel a channel-forming core consisting of glass is arranged inside the casting mould between the cores that form the cylinder recesses in such a manner that it is supported only at its ends.

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