DE102006055304A1 - Cast iron cylinder head or engine block contains feed channels for fuel, coolant and oil consisting of steel pipes which are enclosed by cast material without gap and bonded to it by mixed phase of steel and cast iron - Google Patents

Abstract

Cast iron cylinder head or engine block contains feed channels for fuel, coolant and oil. These consist of steel pipes (1) which are enclosed by cast material without a gap and bonded to it by a mixed phase of steel and cast iron. An independent claim is included for a method for producing the cylinder head or engine block comprising forming a core packet consisting of sand cores (7) and pipes in the desired shape of the channel;#casting iron around it in a mold; and#cooling the casting.

Description

The The invention relates to cylinder heads made by casting or cylinder crankcase, which has multiple guide channels for liquids, such as fuel, coolant or oil, wherein the guide channels be poured during the casting of the components.

It is common practice the numerous leadership and Supply channels, for example for fuel and oil transport, in cylinder heads (ZK) and cylinder crankcases (ZKG) by deep hole drilling technology in the cast components. The drilling of exclusively straight segments and their connection put high restrictions on the geometric design castings. This leads to compromises the functional optimization of cylinder head or cylinder crankcase.

The drilling of channels is for example from the DE 30 10 635 C2 known. For this purpose, in several successive, highly precise work steps to be carried out, central main guide channels and secondary guide channels, which form branches to the individual points of need, are drilled into the component.

Especially in fuel return ducts in cylinder heads, which in commercial vehicle engines over a total length must be drilled up to 1 m, around the channels enough material will be present to keep the correct course of the drill during deep hole drilling process and stabilize it. This material is not needed in the operation of the engine and thus provides an unnecessary weight increase Similarly, the drilling of the main oil channel is with the individual branches to the individual needs in the Engine blocks.

The DE 199 61 092 discloses a cooled cylinder head, wherein at least one of the coolant channels consists of a tube which is preformed and is cast in place during casting of the cylinder head. At least one of the coolant passages in the cylinder head consists of a pipe cast into the cylinder head during casting of the cylinder head, approximately parallel to the centerline of the crankshaft between a center plane containing the centerlines of the cylinders and the row of exhaust valves and / or the bank of intake valves across a plurality of cylinders extends.

The DE 103 04 971 A1 relates to a cast cylinder crankcase, which has at least one guide channel as an oil line, which is formed in the form of a tube and molded during casting and directs oil to be lubricated crankshaft bearing and / or camshaft bearing. The guide channels are each bent. The individual separate guide channels are connected to each other after casting by a subsequently introduced by drilling main oil passage.

At the Pouring of pipes as a guide channel results The problem is that the pipes with the Umgeießen the molten metal due to thermal expansion from its position move or warp. This is especially true for the relative long media supplies the case, spread over the entire Longitudinal axis of the engine block extend. Often there is a lack of connection of the cast-in pipe to the casting metal. Particularly disadvantageous is the formation of columns, since here the heat flow is impeded, or potential leaks for guided in the cylinder crankcase or cylinder head Liquids arise.

It Object of the invention cylinder heads and / or cylinder crankcase with complex guide channels for Liquids with good material and form-fitting Connection to provide, as well as a method for cost-effective and error-free production of these guide channels show.

According to the invention a cast cylinder head and / or a cylinder crankcase is provided to solve this problem, the / which includes a plurality of cast-in channels, which are formed as guide channels for liquids such as fuel, coolant or oil, wherein the cylinder head and / or cylinder crankcase made of cast iron and the Guide channels ( 1 ) are formed from steel tubes and the guide channels ( 1 ) gap-free from the encapsulation ( 3 ) and mixed phases of steel and cast iron metallurgically to the Umguss ( 3 ) are connected with the features of claim 1.

• – Herstellung von Gießkernpaketen (6) aus Sandkernen (7) und Stahlrohr in der Form zu bildender Führungskanäle (1)
• – Einbringen der Gießkernpakete (6) in die Gießform für Zylinderköpfe und/oder Zylinderkurbelgehäuse
• – Abgießen der Zylinderköpfe und/oder Zylinderkurbelgehäuse mit Gusseisen,
• – geregeltes Abkühlen des Gusstückes dadurch gekennzeichnet, dass, die Führungskanäle (1) aus Stahlrohr spaltfrei vom Umguss (3) umgeben werden und Mischphasen aus Stahl und Gusseisen gebildet werden, die Stahlrohr und Umguss (3) metallurgisch verbinden mit den Merkmalen des Anspruchs 12.

A further solution according to the invention is a method for producing guide channels for liquids, in particular for fuel, coolant or oil, in cast cylinder heads and / or cylinder crankcases, comprising the steps

• - manufacture of core packages ( 6 ) from sand cores ( 7 ) and steel pipe in the form of forming guide channels ( 1 )
• - introduction of the core packages ( 6 ) in the mold for cylinder heads and / or cylinder crankcases
• Casting the cylinder heads and / or cylinder crankcases with cast iron,
• Controlled cooling of the casting, characterized in that the guide channels ( 1 ) made of tubular steel without gaps from the encapsulation ( 3 ) and Mischpha made of steel and cast iron, the steel pipe and the casting ( 3 metallurgically connect with the features of claim 12.

For the cylinder heads according to the invention or Cylinder crankcase, it is essential that the Materials of the cast-in guide channel and the Umgusswerkstoff from cylinder crankcase or cylinder head to each other are coordinated. Thus, it is envisaged that the cylinder head or the cylinder crankcase made of cast iron and the guide channels are formed of steel tubes. Here are the guide channels according to the invention surrounded gap-free from the Umguss. The connection of the cast-in guide channels takes metallurgical form and material over Mixed phases of steel and cast iron.

Cleavage-free is to be understood as meaning that there are no contiguous areas of detachment, steel tube guide channel and cast iron encapsulation. The voids or pores that sometimes occur during casting processes in the transitional area between the guide channel and the encapsulation should not be regarded as a gap. Voids or pores below an area of 5 mm ² or a maximum lateral extent below 5 mm count in each case not to columns in the sense of the invention.

Of the Steel of the steel tube has the advantage that steel under the as cast Guide channel suitable metal alloys a comparatively has low thermal expansion among the service metals. It is particularly advantageous that the steel has a lower thermal Has expansion as the surrounding cast iron. This will when pouring the steel pipe achieved that during cooling after the casting no disappearance of the heated steel pipes of the surrounding cast iron takes place. Steel and cast iron have one excellent chemical and physical compatibility on. It is higher by the opposite of the cast iron Melting point of the steel the risk of melting down or the complete melting of the steel pipes during pouring reduced. Nevertheless, the melting point of the steel is not so high that a superficial melting of the steel tube would be prevented.

It is thus intended that when casting a small part of the steel melts and with liquid iron without gap formation tightly merged. So is also a gap formation during cooling to room temperature avoided. The geometry of the casting has a uniform in the area of the steel tube Material accumulation on to local softening or melting of steel or too fast cooling (quenching) of the steel To avoid melt on the steel pipe surface. Also with too fast cooling of the molten one Cast iron in the area of the cold steel pipe can lead to a gap formation or to an undesirable whiteness of the Cast iron come. An exact vote of the material accumulation of the encapsulation in the area of the steel pipes, with the tubular steel geometry, or their diameter and wall thickness and with the casting temperature is required.

For a particularly strong adhesion is the formation of mixed phases made of steel and cast iron advantageous. It must be ensured that a partial melting of the steel takes place. In preferred Embodiment of the invention, the steel pipe before the sprue with Sn or a Sn alloy treated, which melting point-lowering acts, so that form after the casting Sn-containing mixed phases.

The The invention will be described with reference to schematic drawings and exemplary embodiments explained in more detail below.

there demonstrate:

1 shows a cross section of a section of a cylinder head ( 2 ) with guide channels ( 1 ) and water rooms ( 4 )

2 a cast-off and split in 2 levels cylinder head ( 2 ) with guide channels ( 1 ), with curvature ( 5 ) and cooling water spaces ( 4 ) as well as a separation point ( 8th ) between adjacent segments ( 1a ) and ( 1b )

3 a composite core package ( 6 ) from several casting cores ( 11 ) with inserted steel tubes from segments 1a . 1b and 1c sand cores ( 7 ), a spacing ( 12 )

4 Micrographs of the transition between steel pipe ( 1 ) and casting ( 3 ) cast guide channel for a cast according to the invention component (a) with mixed phases ( 10 ) and a conventional component (b) with a gap ( 9 )

5 two parallel steel tubes ( 1 ), each divided into three segments ( 1a ) 1b ) and ( 1c ) and sand cores ( 7 ) or pipe sleeve ( 13 ) are connected.

The thermal expansion of the steel must be taken into account when designing the steel pipes for the guide channels. At the pouring, the thermal expansion immediately after the mold filling is approx. 11.5 mm / m, assuming a mean temperature of the steel pipe of 1000 ° C. The temperature distribution over the entire steel tube is very different during the casting, so that spatially and temporally different Extensions and stress distributions exist. To accommodate these expansions of the steel tubes without deformation, special precautions must be taken.

In a preferred embodiment of the invention expansion joints are provided for the sprue of the steel tube by at least one or all of the guide channels ( 1 ) into several separate segments ( 1a . 1b . 1c ) are divided from steel tube. The transitions between the individual segments are designed so that they can absorb at least part of the elongation of the steel at the sprue of the guide channel. The individual segments then form in the cast component, cylinder crankcase or cylinder head, for the liquids to be transported through continuous guide channels.

Preference is given to the segments ( 1a . 1b . 1c ) of a respective guide channel ( 1 ) at their separation points ( 8th ) bridged by short channel pieces of cast iron. These short channel pieces in cast iron can be formed, for example, by casting sand cores with the cast iron.

A further embodiment provides that a plurality of adjacent cast-in guide channels ( 1 ) communicate with each other via connecting channels in the cast iron.

A Another preferred embodiment of the separation points between adjacent Segments provides short pipe collars or sleeves made of steel, which overlap on both sides of the respective ends of the segments to be joined. Before casting, the adjacent steel tube segments are in the respective Pipe sleeve inserted. The pipe sleeve forms an outer Enclosing the separation point or expansion joint between the neighboring segments. The fit is just so tight or that prevents penetration of the melt of cast iron but moving the steel tube segments through the thermal Expansion during casting within the pipe sleeve still possible is. By this arrangement, the thermal stresses be effectively degraded during the pouring of the steel tube. Up there the use of sand cores or the like is dispensed with, The later may also be omitted difficult removal of core sand from the guide channel or pipe inside. Through the Umuss the pipe sleeve becomes metallurgical attached to the Umguss and the previously movable connection point firmly fixed. Preference is given to pipe sleeve and steel pipe from the same Material.

Of the Space required for the thermal expansion depends of the length of the respective segment. The length the expansion joints and the pipe sleeves is accordingly interpreted.

Possibly can connect to the pipe cuffs connection openings or connecting branch for branches, such as cross channels be provided for the appropriate needs. That `s how it is possible that the pipe sleeves as cross-connection parts are designed for two parallel steel tubes, whereby a connecting channel between two parallel guide channels is formed.

In the cylinder heads or cylinder crankcases, the guide channels ( 1 ) Preferably approximately parallel to the main axis of the cylinder head and / or cylinder crankcase. Preferably, at least one of the guide channels in the cylinder crankcase is bent at one or both of its ends in the direction of the cylinder head or laterally outwards, so that the media supply or discharge can take place via the adjacent cylinder head or connected units. Preferably, the curvature ( 5 ) in the range of 65 to 105 °. It is particularly favorable if no separate steel tube segments adjoin one another in the region of the curvature and no branching points of the channel system are present. As a result, the preferred laminar flow of the transported liquid is not disturbed by turbulence.

Preferably, the guide channels ( 1 ) made of tubular steel on a scale-free and smooth inner surface. This is particularly important for a turbulence-free liquid flow of importance. Particularly preferably, the inner steel surface is bare and has a surface roughness below 100 microns.

In a further embodiment according to the invention, at least a part of the guide channels ( 1 ) or at least one of its segments ( 1a . 1b . 1c ) through a cooling water space ( 4 ). 1 shows a particularly advantageous embodiment in the form of a section of a cylinder head. Here run 2 parallel guide channels ( 1 ) as fuel return channels and thereby cut several water spaces ( 4 ). Within the section shown, the guide channels have no segmentation.

A further embodiment provides that the at least one guide channel ( 1 ) forms a running in the longitudinal axis of a cylinder crankcase main oil passage having branches to crankshaft and / or camshaft bearing and supplies the bearings with oil.

• – Herstellung von Gießkernpaketen (6) aus Sandkernen (7) und Stahlrohr in der Form zu bildender Führungskanäle (1)
• – Einbringen der Gießkernpakete (6) in die Gießform für Zylinderköpfe und/oder Zylinderkurbelgehäuse
• – Abgießen der Zylinderköpfe und/oder Zylinderkurbelgehäuse mit Gusseisen,
• – geregeltes Abkühlen des Gusstückes dadurch gekennzeichnet, dass, die Führungskanäle (1) aus Stahlrohr spaltfrei vom Umguss (3) umgeben werden und Mischphasen aus Stahl und Gusseisen gebildet werden, die Stahlrohr und Umguss (3) metallurgisch verbinden.

The inventive method for the production of guide channels for liquids, in particular for fuel, coolant or oil, in cast cylinder heads and / or Zylinderkurbelgehäu sen, provides at least the following procedural steps:

• - manufacture of core packages ( 6 ) from sand cores ( 7 ) and steel pipe in the form of forming guide channels ( 1 )
• - introduction of the core packages ( 6 ) in the mold for cylinder heads and / or cylinder crankcases
• Casting the cylinder heads and / or cylinder crankcases with cast iron,
• Controlled cooling of the casting, characterized in that the guide channels ( 1 ) made of tubular steel without gaps from the encapsulation ( 3 ) and mixed phases of steel and cast iron are formed, the steel pipe and the casting ( 3 metallurgically connect.

The Production of Gießkernpakete is advantageously carried out in several steps, wherein first the steel pipe, or provide the pipe segments with connecting or supporting cores become. To enable the correct positioning of steel pipes and to fix them during the casting, they become thus embedded in sand or before shooting sand cores in the Core box inserted. So can an optimal positioning and stability of steel pipes during casting be guaranteed.

If necessary, the pushing or pushing together of the pipe segments by means of pipe collars ( 10 ). The fit, which prevents ingress of the melt of cast iron, but still allows a displacement of the steel tube segments by the thermal expansion during casting within the pipe sleeve, is relatively strong and allows more complex composite pipe structures. This is especially the case if the pipe construction is additionally reinforced with sand cores ( 7 ) is strengthened.

It is also possible segments ( 1a . 1b . 1c ) with different diameters and / or different steel tube wall thicknesses. When connecting the individual segments with each other, the principle of displaceable inserted connection as in the pipe collars can take. Thus, a segment of smaller diameter can be plugged into a larger diameter, the fit is only designed so tight that can compensate for thermal expansion by displacement of the segments against each other during encapsulation. The overlap is, as in the pipe segments, preferably in the range of a few mm, in particular between 3 and 15 mm.

5 shows two parallel steel tubes ( 1 ), each in three segments 1a . 1b , and 1c are divided. The segments and the parallel steel tubes are over sand cores ( 7 ) connected with each other. The segments are cut through in the sand cores ( 7 ) embedded spacers separately.

The Spacers are made of easily deformable material, allowing them yield during casting of the thermal expansion of the steel tube segments can. In addition, the material must be so far be fireproof and tight, that it penetrates the melt Cast iron prevents. Suitable materials are, for example Felts of inorganic fibers, special elastic sand cores or the like.

3 shows a composite core package ( 6 ) from several casting cores ( 11 ) and with inserted steel tubes according to 5 , The sand cores ( 7 ) form support and fixation points for the steel tubes. The core package corresponds to half an arrangement for a cylinder head of a 6-cylinder inline engine for commercial vehicles. The spacing ( 12 ) of the casting cores ( 11 ) to the steel tube segments ( 1a . 1b . 1c ) is chosen here so that the material accumulation of the cast iron during encapsulation allows an optimal melting of the steel pipe surface and the formation of a solid mixed structure. The gap formation is thereby prevented.

The Thickness of the steel pipe wall, the accumulation of material of the encapsulation in the field of management channels, respectively the geometry of the casting, as well as the casting process preferably coordinated so that the wall of the steel pipe melted up to a maximum of 40% of its thickness melts. More preferably, this thickness is in the range of 5 to 25%. The melted area corresponds essentially to a changed area Structure and mixed phases.

The Ready assembled core packages are placed in the mold for cylinder heads and / or cylinder crankcases introduced and then poured with cast iron.

The Cooling of the casting is regulated and slow to perform.

One with a core package according to 3 Dismantled cylinder head shows 2 , The cylinder head is open in two planes to the guide channels ( 1 ) to clear and to cut. The lower of the two guide channels ( 1 ) shows a curvature ( 5 ), which extends laterally outwards. The guide channels run partly through the cooling water space ( 4 ). The transition region or the separation point ( 8th ) between the segments 1a and 1b is made by cast iron; The steel tube segments do not collide seamlessly and flush here.

The comparison of the connection of steel pipe to casting between a cast according to the invention guide channel and cast according to conventional methods guide channel shows 4 , In conventional component b) is clearly a gap ( 9 ) between the material of the steel tube ( 1 ) and the cast iron ( 3 ) to recognize. A metallurgical connection via the formation of mixed phases is also not recognizable in the beginning. In the component a) according to the invention, no gap is discernible. Rather, steel ( 1 ) and cast iron ( 3 ) over a mixed phase ( 10 ) connected metallurgically miteinender. The black-colored phases of the cast iron extend into the area of the steel with the formation of mixed phases with different depths. These are essentially carbon precipitates or graphite.

For a reliable continuous operation and a high Durchzastzleistung the guide channels is a smooth and corrosive or scale-free inner surface of the cast-in steel tubes significant. In the case of the production of guide channels By casting sand cores remain on the surface usually a scale layer and an adherent layer of sand. This is usually removed by sandblasting. This Process step but should in the inventive Procedure be saved. This results in the sprue the steel pipes still the problem of scale formation or removal the scale layer.

In a further embodiment of the invention Method is therefore provided that the steel pipes evacuated during casting or under a slight overpressure of oxygen-free Atmosphere are kept. This will give you access prevented by atmospheric oxygen. This can be done, for example, by evacuation or inert gas flushing when pouring done. Prefers However, the appropriate atmosphere will be before pouring set and then just kept. So the steel pipes are preferred evacuated before casting or under a slight overpressure made of oxygen-free atmosphere and thus gastight locked.

A Another variant to prevent the formation of scale provides for inner surface of steel pipes before casting with reducing agents to coat. The coated steel tubes can to be opened open or gas-tight during the encapsulation. The reducing agents are preferably selected from metal alloys on the Based on Al, Mg and / or Zn and / or organic amine, urea or hyrdazine compounds. The coating also optionally contains Coating aids, which in particular ensure good adhesion should.

Also the outside of the steel tubes can receive a coating, which improve the formation of the metallurgical bond should. A further embodiment of the invention provides the surface the steel pipes before the casting with Sn or a Sn alloy and / or with a size comprising Na borate, K-Al fluoride and / or Zr fluoride to coat.

These Some substances act as fluxes and improve wetting of the steel through the molten cast iron and partly as melting point-degrading for steel.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3010635 C2 [0003]
• - DE 19961092 [0005]
• - DE 10304971 A1 [0006]

Claims (22)

Cast cylinder head and / or cylinder crankcase, which comprises a plurality of cast-in channels, which are formed as guide channels for liquids, in particular fuel, coolant or oil, characterized in that the cylinder head and / or cylinder crankcase made of cast iron and the guide channels ( 1 ) are formed from steel tubes, wherein the guide channels ( 1 ) gap-free from the encapsulation ( 3 ) and mixed phases of steel and cast iron metallurgically to the Umguss ( 3 ) are connected. Cylinder head and / or cylinder crankcase after Claim 1, characterized in that the mixed phases of steel and cast iron Sn included. Cylinder head and / or cylinder crankcase according to claim 1 or 2, characterized in that at least one or all of the guide channels ( 1 ) into several separate segments ( 1a . 1b . 1c ) are divided from steel tube. Cylinder head and / or cylinder crankcase according to claim 3, characterized in that the segments ( 1a . 1b . 1c ) of a guide channel ( 1 ) at their separation points ( 8th ) are bridged over channel pieces in the cast iron, so that a continuous guide channel ( 1 ) is formed. Cylinder head and / or cylinder crankcase according to claim 4, characterized in that a plurality of adjacent running cast guide channels ( 1 ) communicate with each other via connecting channels in the cast iron. Cylinder head and / or cylinder crankcase according to one of the preceding claims, characterized in that the guide channels ( 1 ) extend approximately parallel to the main axis of the cylinder head and / or cylinder crankcase. Cylinder head and / or cylinder crankcase according to one of the preceding claims, characterized in that at least one of the guide channels has a curvature ( 5 ) in the range of 65 to 105 °. Cylinder head and / or cylinder crankcase according to one of the preceding claims, characterized in that the guide channels ( 1 ) made of tubular steel have a scale-free and smooth inner surface. Cylinder crankcase according to one of the preceding claims, characterized in that at least a part of the guide channels ( 1 ) or at least one of its segments ( 1a . 1b . 1c ) through a cooling water space ( 4 ) of the cylinder crankcase ( 2 ) runs. Cylinder crankcase according to one of claims 1 to 8, characterized in that at least one of the guide channels ( 1 ) forms a main oil passage having branches to crankshaft and / or camshaft bearing Cylinder head according to one of claims 1 to 8, characterized in that at least one of the guide channels ( 1 ) forms a fuel line, in particular a fuel return passage. Method for producing guide channels for liquids, in particular for fuel, coolant or oil, in cast cylinder heads and / or cylinder crankcases, comprising the steps - production of core packages ( 6 ) from sand cores ( 7 ) and steel pipe in the form of forming guide channels ( 1 ) - introduction of the core packages ( 6 ) in the casting mold for cylinder heads and / or cylinder crankcases - casting of the cylinder heads and / or cylinder crankcases with cast iron, - controlled cooling of the casting, characterized in that, the guide channels ( 1 ) made of tubular steel without gaps from the encapsulation ( 3 ) and mixed phases of steel and cast iron are formed, the steel pipe and the casting ( 3 metallurgically connect. A method according to claim 12, characterized in that in the manufacture of Gießkernpakete several segments ( 1a . 1b . 1c ) of tubular steel over sand cores and / or slidably mounted pipe collars ( 13 ) with each other to a guide channel ( 1 ) get connected. Method according to claim 12, characterized in that segments ( 1a . 1b . 1c ) are selected with different diameters and / or different steel tube wall thicknesses. A method according to claim 12, 13 or 14, characterized in that in the manufacture of core cores ( 6 ) from sand cores ( 7 ) and steel pipe, first several steel tubes or segments running in the same direction ( 1a . 1b . 1c ) over sand cores ( 7 ). A method according to claim 12, 13 or 14, characterized in that in the manufacture of core cores ( 6 ) from sand cores ( 7 ) and steel tube, a plurality of corotating segmented steel tubes are connected between the segments via sand cores. Method according to one of claims 12 to 16, characterized in that the steel pipes be evacuated during casting or placed under a slight overpressure from an oxygen-free atmosphere. Method according to one of claims 12 to 16, characterized in that the steel pipes evacuated before the casting or under a slight overpressure of oxygen-free Atmosphere set and sealed gas-tight. Method according to one of claims 12 to 18, characterized in that inner surface of the steel pipes coated with reducing agents before casting. Method according to claim 19, characterized that the reducing agents are selected from metal alloys based on Al, Mg and / or Zn and / or organic amine, Urea or hyrdazine compounds and coating aids. Method according to one of claims 12 to 20, characterized in that the thickness of the Stahlrohrwandung in the On the geometry of the casting and the casting process is tuned that the wall when pouring until to 40% of its thickness melts. Method according to one of claims 12 to 21, characterized in that the outside of the steel pipes comprising Sn or Sn alloy and / or a size Na borate, K-Al fluoride and / or Zr fluoride is coated.