DE102006055304B4 - Cylinder heads and cylinder crankcases with complex fluid ducts and their manufacture - Google Patents

Abstract

Cast cylinder head and / or cylinder crankcase, which comprises several cast-in channels, which are designed as guide channels for liquids, in particular fuel, coolant or oil, the cylinder head and / or cylinder crankcase being made of cast iron and the guide channels (1) being made of steel pipes, wherein the guide channels (1) are surrounded by the encapsulation (3) without any gaps and are metallurgically connected to the encapsulation (3) from mixed phases of steel and cast iron, characterized in that at least one or all of the guide channels (1) are divided into several separate segments (1a, 1b, 1c) are divided from steel pipe.

Description

The invention relates to cylinder heads or cylinder crankcases produced in casting technology, which have a plurality of guide channels for liquids, such as fuel, coolant or oil, wherein the guide channels are cast during the casting of the components.

It is common practice to produce the numerous guide and supply channels, for example for fuel and oil transport, in cylinder heads (ZK) and cylinder crankcases (ZKG) by deep hole drilling technology into the cast components. The drilling of the exclusively straight segments and their connection places high restrictions on the geometric design of the castings. This leads to compromises with regard to 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.

In particular, in fuel return passages in cylinder heads, which are drilled in commercial vehicle engines over a total length of up to 1 meter, there must be enough material around the channels to allow and stabilize the proper course of the drill during the downhole drilling operation. This material is not needed in the operation of the engine and thus represents an unnecessary increase in weight. Similarly, the drilling of the main oil channel, with the individual branches to the individual needs in the cylinder crankcase.

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.

The DE 1151901 discloses a method for pouring pipelines. Before pouring, the tubes are soldered at their ends in a gas atmosphere reducing the oxides, but inert to the tube material, and then poured into the casting.

The DE 4414095 A1 relates to a method of joining a first metal workpiece with at least one second metal workpiece to a composite component. The second workpiece is poured onto the first. The material of the second workpiece has an at least 150 ° C higher liquidus temperature and shrinks on the first workpiece.

From the DE 4341040 A1 For example, a metal engine block with at least one channel assembly is known. The channel arrangement is formed by a prefabricated pipe system, which is encapsulated at least with a part of its channel lengths of the metallic material. This makes it possible to insert the channel assembly as an insert in the mold.

From the DE 3243377 A1 is known a cast workpiece with molded channel. It is inserted into the mold before the introduction of the melt, provided with the channel metallic in cross-section two- or multi-part component which is poured into the workpiece or partially encapsulated with this.

When pouring pipes as a guide channel, there is the problem that move the pipes during casting with the molten metal by thermal expansion of their position or forgiven. This is the case in particular for the relatively long media supplies, which extend over the entire longitudinal axis of the engine block. Often there is a lack of connection of the cast-in pipe to the casting metal. Particularly disadvantageous is the formation of gaps, as here the heat flow is hindered, or potential leaks arise for guided in the cylinder crankcase or cylinder head fluids.

It is an object of the invention to provide cylinder heads and / or cylinder crankcases with complex running guide channels for liquids with good material and positive connection, as well as to provide a method for cost-effective and error-free production of these guide channels.

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

wobei 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 11.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 cast piece

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 with the features of claim 11.

It is essential for the cylinder heads or cylinder crankcases according to the invention that the materials of the cast-in guide channel and the encircling material of the cylinder crankcase or cylinder head are matched to one another. Thus, it is provided that the cylinder head or the cylinder crankcase made of cast iron and the guide channels are made of steel pipes. Babel are the guide channels according to the invention without a gap surrounded by the Umguss. The connection of the cast-in guide channels is metallurgically positive and cohesive via 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.

The steel of the steel tube has the advantage that steel has a comparatively low thermal expansion among the useful metals among the metal alloys suitable as a cast-in guide channel. It is particularly advantageous that the steel has a lower thermal expansion than the surrounding cast iron. As a result, during the pouring of the steel pipe is achieved that takes place during the cooling after casting no disappearance of the heated steel pipes from the surrounding cast iron. Steel and cast iron have excellent chemical and physical compatibility. In this case, the risk of melting through or the complete melting of the steel pipes during pouring is reduced by the opposite of the cast iron higher melting point of the steel. Nevertheless, the melting point of the steel is not so high that a superficial melting of the steel pipe would be prevented.

It is thus envisaged that during casting a small portion of the steel melts and fuses tightly with liquid iron without formation of gaps. Thus, a gap formation during cooling to room temperature is avoided. The geometry of the casting has a uniform accumulation of material in the region of the steel tube to avoid local softening or melting of the steel or too rapid cooling (quenching) of the melt on the steel tube surface. Even if the molten cast iron cools down too quickly in the area of the cold steel pipe, a gap formation or an undesired white solidification of the cast iron may occur. An exact coordination of the material accumulation of the encapsulation in the area of the steel tubes, with the steel tube geometry, or their diameter and wall thickness and with the casting temperature is required.

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

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

Showing:

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 casting, so that there are spatially and temporally different expansions and stress distributions. 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 ) überbruckt 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 further preferred embodiment of the separation points between adjacent segments provides short tube sleeves 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 inserted into the respective tube sleeve. The pipe sleeve thereby forms an outer envelope of the separation point or expansion joint between the adjacent segments. The fit is only so tight or firm that penetration of the melt is prevented from cast iron, but a displacement of the steel tube segments by the thermal expansion during casting within the pipe sleeve is still possible. By this arrangement, the thermal stresses at the gate of the steel pipe can be effectively reduced. Since it is dispensed with the use of sand cores or the like, also eliminates the eventual under certain circumstances difficult removal of core sand from the Führungskanal- or tube interior. By the Umguss the pipe sleeve is metallurgically connected to the Umguss and fixes the previously displaceable connection point. Preference is given to pipe sleeve and steel pipe made of the same material.

The space requirement for the thermal expansion depends on the length of the respective segment. The length of the expansion joints and the pipe collars must be interpreted accordingly.

Optionally, connecting openings or connecting branches for branches, such as cross channels to the corresponding demand points, may be provided on the pipe collars. It is also possible that the pipe collars are formed as cross-connection parts for two parallel steel tubes, whereby a connection channel between two parallel guide channels is formed.

In the cylinder heads or cylinder crankcases run the Fuhrungskanäle ( 1 ) Preferably approximately parallel to the main axis of the cylinder head and / or cylinder crankcase. At least one of the guide channels in the cylinder crankcase is preferably 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 method according to the invention for the production of guide channels for liquids, in particular for fuel, coolant or oil, in cast cylinder heads and / or cylinder crankcases, provides at least the following method 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 cast piece

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 the Gießkernpakete is advantageously carried out in several steps, initially the steel pipe, or the pipe segments are provided with connecting or supporting cores. In order to enable the correct positioning of steel pipes and to fix them during casting, they are thus embedded in sand or inserted into the core bushing before shooting sand cores. This ensures optimal positioning and stability of the steel pipes during casting.

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 firm 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 so that they can yield during casting of the thermal expansion of the steel tube segments. In addition, the material must be sufficiently refractory and dense to prevent the melt from infiltrating cast iron. Suitable materials include 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 tube wall, the accumulation of material of encapsulation in the region of the guide channels, or the geometry of the casting, as well as the casting process are preferably coordinated so that the wall of the steel tube melts during transfusion to a maximum of 40% of its thickness. More preferably, this thickness is in the range of 5 to 25%. The melted area corresponds essentially to a range of altered microstructure and mixed phases.

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

The cooling of the casting is regulated and carried out slowly.

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 Durchsastzleistung the guide channels is a smooth and corrosion or scale-free inner surface of the cast steel pipes of importance. In the case of the production of guide channels by casting sand cores usually remain on the surface of a scale layer and an adherent layer of sand. This is usually removed by sandblasting. However, this process step should be saved in the procedure according to the invention. Nevertheless, the problem of the formation of scale or the removal of the scale layer occurs when the steel tubes are sprinkled.

In a further embodiment of the method according to the invention it is therefore provided that the steel pipes are evacuated during casting or kept under a slight overpressure from an oxygen-free atmosphere. As a result, the access of atmospheric oxygen is prevented.

This can be done, for example, by evacuation or inert gas flushing during casting. Preferably, however, the corresponding atmosphere is adjusted before pouring and then held only. Thus, the steel tubes are preferably evacuated prior to casting or placed under a slight overpressure from an oxygen-free atmosphere and hermetically sealed gas-tight.

Another variant for preventing scale formation envisages coating the inner surface of the steel pipes with reducing agents before casting. The coated steel tubes can be closed open or gas-tight during encapsulation. The reducing agents are preferably selected from metal alloys 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 should ensure good adhesion.

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

These substances act partly as fluxes and improve the wetting of the steel by the molten cast iron and partly as melting point depressing for steel.

Claims (20)

Cast cylinder head and / or crankcase comprising a plurality of cast-in channels formed as guide channels for fluids, in particular 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, wherein the guide channels ( 1 ) gap-free from the encapsulation ( 3 ) and mixed phases of steel and cast iron metallurgically to the Umguss ( 3 ), 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 1, characterized in that the mixed phases of steel and cast iron Sn. Cylinder head and / or cylinder crankcase according to claim 1 or 2, 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 3, 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 7, 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 7, 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 - pouring of the cylinder heads and / or cylinder crankcase with cast iron, - controlled cooling of the casting, wherein 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 connecting, characterized in that in the production of the core cores 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 11, characterized in that segments ( 1a . 1b . 1c ) are selected with different diameters and / or different steel tube wall thicknesses. A method according to claim 11 or 12, 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 ). Method according to claim 11, 12 or 13, 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 11 to 14, characterized in that the steel pipes are evacuated during casting or placed under a slight overpressure of oxygen-free atmosphere. Method according to one of claims 11 to 15, characterized in that the steel pipes are evacuated prior to casting or placed under a slight overpressure of oxygen-free atmosphere and sealed gas-tight. Method according to one of claims 11 to 16, characterized in that the inner surface of the steel tubes is coated with reducing agents prior to casting. A method according to claim 17, characterized in 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 11 to 18, characterized in that the thickness of the steel pipe wall is matched in such a way to the geometry of the casting and the casting process, that its wall melts when encapsulating up to 40% of its thickness. Method according to one of claims 11 to 19, characterized in that the outside of the steel tubes with Sn or Sn alloy and / or with a size comprising Na borate, K-Al-fluoride and / or Zr fluoride is coated.

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