EP0683858B1 - Piston engine, especially piston internal combustion engine with reinforced engine block - Google Patents

Abstract

The invention pertains to a piston engine, especially piston internal combustion engine, wherein cylinders, pistons, crankshaft and crankshaft bearings are arranged in an engine block (1), areas of the engine block being fitted with cap and/or cup-shaped coverings and the walls of the cylinder block (2) and/or of the coverings having at least in some areas solidly connected reinforcing components (4) made of a material that differs from the base material in the engine block (1) and/or the coverings and that has a higher modulus of elasticity than the base material.

Description

Piston engines, in particular piston internal combustion engines, due to the changing processes in the cylinder space, for example through the combustion process, however also due to mechanical influences on vibrations excited, which is also called sound on the surfaces of the piston engine be emitted in the form of airborne sound and / or about the bearing of the piston machine in the foundation or the vehicle body in vehicles as structure-borne noise to get redirected.

Because of the adverse effects on people and the environment efforts are being made to reduce such noise emissions. As shown in DE-A-28 49 613, an attempt is made to use a sound shield by arranging an elastic with the Engine block connected to a piston internal combustion engine To achieve sound insulation. Furthermore, according to DE-A-28 01 431 proposed the entire piston internal combustion engine with the help of structure-borne soundproofing support elements to be stored in an outside tub. A disadvantage of such Soundproofing is that they do much of the Machine and therefore attaching attachments and / or additional units, such as engine supports, starters, Alternator or also of gas supply lines and gas discharge lines with special needs. In many cases it cannot be done here prevent such sound insulation sleeves for the Attachment of such attachments and / or additional units be interrupted, reducing their effectiveness becomes. In addition, such sound insulation measures affect the heat balance of a piston internal combustion engine.

Because of the disadvantages described above, one also has tries to fight the sound propagation by that an attempt was made to prevent sound generation or at least to decrease. In addition to reducing Causes of suggestions, for example by optimizing the It is particularly useful in the combustion process to transmit structure-borne noise and the sound radiation on the surface to reduce the piston internal combustion engine. That was by causing the piston engine especially in their thin-walled areas stiff, in particular flexurally or torsionally rigid, with respect to the airborne sound radiation the vibrating Areas as small and / or thick-walled as possible become. In particular by increasing the wall thickness occur alongside an undesirable magnification the weight increased especially with cast components Cast defects, such as blowholes, pores or the like. Therefore, according to DE-A-35 44 215, it has already been proposed the overall rigidity of the engine block through a system of reinforcing ribs on the side walls in the cylinder area to improve. This allows the appropriate Design of the ribs undesirable casting defects avoid and high rigidity of the cylinder block achieve.

From EP-A-0 052 818 it is known in the foot of an engine block cast a sheet steel frame out of aluminum, which is each provided with cross struts, which are in the plane of the engine foot down to the parting plane of the crankshaft bearings extend so as to vibrate the crankshaft bearings to reduce in the axial direction of the crankshaft. The each wall areas between the individual crankshaft bearings, that connect the foot to the cylinder area and that Form crankcase, are executed without any stiffeners, so that they can swing freely.

From EP-A-0 064 457 it is known that limit the crankcase Walls of a cylinder block with one facing outwards projecting bridge, which is made of the same material as the cylinder block is made.

From US-A-5,218,938 an oil pan made of cast aluminum is known, those to increase rigidity and reduce vibration with a wall made entirely of webs covering grid arrangement is provided which are made of the same material as the oil pan.

The proposal according to DE-A-40 17 139 is also the idea based on the necessary rigidity of the engine block over the effect targeted attachment of ribbons and ribs. At This proposal will be done in particular through the connection the crankshaft bearing on the cylinder block and on the crankcase side walls over a variety of reinforcing ribs reached so that the rigidity of the engine block structure is increased overall. However, this is appropriate Weight increase linked. However, weight gain is to avoid from an economic point of view.

The invention is based on the object, the vibration and Noise development of a piston machine, especially one Piston engine, by designing the engine block structure decrease, taking the total weight if possible may not be increased.

According to the invention, this object is achieved with a piston machine, in particular a piston internal combustion engine in which Cylinder, piston, crankshaft and crankshaft bearing in one engine block are arranged, areas on the engine block are provided with cover and / or trough-shaped covers and the walls of the engine block and / or the covers at least in some areas with rib-shaped, reinforcing Components are firmly connected from one of the base material of the engine block and / or the covers Component material consist of a higher modulus of elasticity has than the base material. The special advantage The solution according to the invention is that for the component material Materials can be selected alongside a modulus of elasticity many times higher than that Base material depending on the type of base material used have lower density. This ensures that with the same total weight of the piston machine Stiffness is increased in the areas concerned and / or even the total weight can be reduced. To the covers in the sense of the The present invention includes, for example, the cylinder head cover, Timing gear covers, the crank or oil pan and similar elements of the engine structure. Especially in piston internal combustion engines is with regard to task of noise reduction also to be solved associated gearbox to be expected, since the walls of a flanged gear housing, for example can radiate. Again, with an arrangement of components in the wall reduces vibration Achieve stiffening. In the same way, too the intake and / or exhaust pipes with tubular components inside and / or outside with web or rib-shaped components reinforce outside vibration-reducing, so that also over these structures, which belong to the engine block in the broader sense there is no or only a low level of sound radiation.

In a preferred embodiment, the component material ceramic materials, in particular oxide ceramic materials intended. These have a much higher modulus of elasticity than the gray cast iron usual as base material or Cast aluminum. In the case of using gray cast iron as The base material is the density of ceramic materials much smaller than the density of the base material. When using cast aluminum, the density is more ceramic Materials roughly the same. Because of these material properties can stiffening components made of ceramic Materials with the same mass about 12 times stiffness compared to an identical design made of gray cast iron. For example, ribs have the same rigidity from a ceramic material about 70% less mass as ribs made of gray cast iron. Another advantage lies in that such a rib-shaped design Components with a given same stiffness due to the higher modulus of elasticity geometric dimensions compared to a rib from the Reduce the base material so that the overall volume of the internal combustion engine is reduced. This allows stiffening measures for noise reduction even with a given production system be effectively introduced into the components.

In an advantageous embodiment of the invention is also provided that the components are each at least partially are positively embraced by the base material. Here is in an expedient embodiment of the invention provided that the reinforcing components by at least partial casting with the base material with this are connected. The particular advantage of overmolding is there in the fact that the base material is already in the casting process the correspondingly held components in the molds, in particular ceramic components, flows around in the fastening area, so that larger dimensional deviations on the part of the ceramic Components can be accepted. That allows such Ceramic components as they come from the firing process, without using any post-processing. There during the cooling phase the base material shrinks more than the ceramic components used become the ceramic components held under compressive stress in the base material. This is particularly advantageous for brittle ceramic material.

In another advantageous embodiment of the invention it is envisaged that the reinforcing components via auxiliary materials are firmly connected to the base material. Organic or inorganic materials come as auxiliary materials Consider adhesive or soldering the ceramic Components using metallic or non-metallic Solders, for example glass or enamel solders.

In an advantageous embodiment of the invention is also provided that the reinforcing components in the area the crankshaft bearing are web-shaped and connect the bearing area to the wall of the engine block. This arrangement is particularly effective because of the here Available space through the crankshaft connected counterweights fixed is. Another increase in the rigidity of the bearing area by connecting the adjacent walls of the engine block is therefore about such web-shaped supports only by using materials with a higher Modulus of elasticity as the base material used, in particular through the use of ceramic materials possible. As a result, they are used for structure-borne noise transmission critical vibrations of the crankshaft bearing both in the longitudinal direction of the engine and in the direction of the transverse engine axis and effectively suppresses the motor vertical axis.

Fig. 1

einen Motorblock einer Kolbenbrennkraftmaschine mit in Längsrichtung angeordneten versteifenden, rippenförmigen Bauteilen,

Fig. 2

einen Motorblock mit versteifenden Bauteilen im Bereich des Kurbelgehäuses,

Fig. 3

eine Abwandlung der Ausführungsform gem. Fig. 1,

Fig. 4

eine Abstützung des Kurbelwellenlagers am Kurbelgehäuse über versteifende stegförmige Bauteile,

Fig. 5

einen Teilausschnitt einer Motorblockwandung mit nachträglich aufgebrachtem verstärkendem Bauteil,

Fig. 6

unterschiedliche Ausführungsbeispiele für in den Grundwerkstoff des Motorblocks eingegossene rippenförmige Bauteile in einer Schnittdarstellung,

Fig. 7

einen vollständig vom Grundwerkstoff umschlossenes rippenförmiges Keramikbauteil in einer Schnittdarstellung,

Fig. 8

eine bevorzugte Ausführungsform einer eingegossenen Rippe,

Fig. 9

die Rippenform gem. Fig. 8 in einer eingelöteten Ausführungsform.

The invention is explained in more detail with reference to schematic drawings of exemplary embodiments. Show it:

Fig. 1

an engine block of a piston internal combustion engine with stiffening, rib-shaped components arranged in the longitudinal direction,

Fig. 2

an engine block with stiffening components in the area of the crankcase,

Fig. 3

a modification of the embodiment according. Fig. 1

Fig. 4

a support of the crankshaft bearing on the crankcase via stiffening web-shaped components,

Fig. 5

a partial section of an engine block wall with subsequently applied reinforcing component,

Fig. 6

different exemplary embodiments for rib-shaped components cast into the base material of the engine block in a sectional view,

Fig. 7

a rib-shaped ceramic component completely enclosed by the base material in a sectional view,

Fig. 8

a preferred embodiment of a cast-in rib,

Fig. 9

the rib shape acc. Fig. 8 in a soldered embodiment.

In Fig. 1 is an engine block 1 of a four-cylinder piston internal combustion engine shown, the upper section 2 the Cylinder block forms and its lower section 3 the includes the upper part of the crankcase. The crankcase is on the bottom with a not shown here Enclosed crankcase. The cylinder block 2 and that Crankcase 3 are particularly useful in vehicle engines executed as a component. To reinforce the construction are on the cylinder block 2 as well as on the crankcase 3 extending in the longitudinal direction of the internal combustion engine rib-shaped components 4 attached. This rib-shaped Components 4 consist of a material that is a higher E-module as the base material, preferably made of a ceramic material. If the engine block 1 For example, made of gray cast iron, then the Components 4 compared to the base material gray cast iron, for example an approximately three times higher modulus of elasticity and about half Density of the base material. The coefficient of thermal expansion is similar to that of gray cast iron, so that a composite cast iron and ceramics are unproblematic from this point of view is. If aluminum is used as the basic material, then own it the components 4, for example when using aluminum oxide ceramic a 5-fold higher modulus of elasticity than the base material with a similar density. For example, such Rib-shaped components 4 made of ceramic, as shown in FIG. 1 are indicated with the same stiffness in use of gray cast iron as the base material is 70% lower Mass as ribs made of gray cast iron. Such rib-shaped Components can on the crankcase 3 both on the Arranged outer wall as well as on the inner wall become. In the arrangement shown, the Rigidity of the engine block, globally and above all locally especially with respect to the motor vertical axis, so that the Development of vibrations and impedes the amplitude resulting vibrations of the engine block is reduced.

In Fig. 2, an engine block is shown in the the outer wall of the crankcase 3 next to one in Rib-shaped component 4 extending in the longitudinal direction of the motor Made of oxide ceramic to stiffen the crankcase wall Ribs 5 and 6 extending in a cross shape to one another are that can also be made of ceramic.

Fig. 3 shows a modification of the embodiment according to. Fig. 1. Here are those extending in the longitudinal direction rib-shaped components 4 interrupted in their longitudinal direction, the interruption is preferably in the range the connection points of the bearing walls with the outer walls of the engine block are provided. This will the freely vibrating outer surfaces of the engine block structure downsized and the acoustic behavior of the Engine block structure significantly improved. Such ribs lead to an increased at the interruption points 7 Impedance jump and thus in particular to a reduction the structure-borne noise transmission. The geometry of the break points can, as for example for the area 7.1 shown, wedge-shaped or trapezoidal be or rounded as shown for area 7.2 be trained. This construction with broken short ribs takes into account the special circumstances of the brittle material ceramic. The construction with interrupted Ribs are also used for pure cast constructions advantageous.

4 is a vertical section through an engine block 1 shown, in which the cylinder block 2 and the crankcase 3 are integrally connected. The support 8 for the main bearing is a rib 10, 11 reinforced bearing wall 9 firmly connected to the engine block and with additional, web-shaped ribs 12, 13, 14 with the wall of the crankcase 3 firmly connected, so that there is additional stiffening here. To increase the rigidity while reducing the weight it is provided that at least part of the web-shaped Ribs 12, 13 and / or 14 made of a ceramic material consists, preferably those reinforcing ribs, which are arranged perpendicular to the bearing wall 9, either reinforced with ceramic material or completely ceramic material are executed. This will the vibrations critical for structure-borne noise the crankshaft bearing both in the engine longitudinal direction as well as in relation to the motor transverse and motor vertical axis effectively suppressed and the input impedance at the main bearing clearly increased.

5 schematically shows a possibility of connection a rib-shaped component 4 with the wall of a Engine blocks, for example with the wall of the crankcase 3 shown. The component 4 is in this embodiment subsequently placed on the crankcase 3, the connection being made using an auxiliary material, for example an adhesive and / or by soldering or Welding. It can be useful here, as shown in FIG. 9 shows in the wall of the engine block during manufacture to provide a trough-shaped depression, in which then the rib-shaped component 4 inserted and by gluing, Solder or weld with the appropriate wall area of the engine block is connected.

6 shows, such rib-shaped components 4 already in the manufacture of the engine block in the base material introduced by casting around such a component become. As the cross-sectional shape 4.1 shows, this must be done the edge of the rib-shaped component to be molded accordingly run thickened, the thickening is to be rounded, so that the occurring Stresses largely as the compressive stress of the Surface of component 4.1 take effect.

In the cross-sectional shape, as for the rib-shaped Component 4.2 is shown, there is an increase the rigidity of the ribs in that the exposed Edge 16 is executed accordingly thickened, so that a higher area moment of inertia, based on the wall of the internal combustion engine to be stiffened. Another advantage of this configuration is that that such a thickened outer edge 16 is also a results in good integration into the molding material. As Fig. 8 shows the thickened area in the molding material 17 embedded in the mold, so that only the base material end of the engine block to be created protrudes. The mold is to be provided in such a way that if possible, the wall thickness in the encapsulation area 18 is essentially constant, so that a "cast-around fold" arises, which the rib-shaped component 4.2 like a "clip stapler" form-fitting surrounds.

Such a rib-shaped component 4.2 from one Ceramic material can also be used directly on the model be attached so that the molding sand the ribs outside form-fitting surrounds. The undercuts can be done here through an easily evaporable material, e.g. B. by wax, must be filled in to prevent sand from entering. Similarly, such ceramic components also in sand cores or metal molds (die casting, die casting) to get integrated. In the lost foam process, the rib-shaped ones are Components 4 directly into the positive from foam used.

6 is also a rib-shaped component 4.3 shown in cross section.

The cross section acc. Fig. 7 shows a rib-shaped reinforcement 19, in which a ceramic component 4 of the cast material is completely enclosed. The complete enclosure is not over the entire length in this embodiment provided that the component 4 to be cast from ceramic Material at least in its end areas in the form must be fixed.

To the so-called when pouring such components 4 It is advisable to avoid thermal shock if the parts 4 to be cast in whole or in part immediately be heated before casting. With electrically conductive Ceramic materials can preheat the ceramic components in the sand form done inductively.

In the area of the cylinder block 2, the invention Teaching not only by applying ceramic Use components as shown in FIG. 1 is. In this area it is also possible to do so trained reinforcing components made of ceramic To arrange material near the threaded pipe, for example pour in so that in addition to increasing the Rigidity in relation to dynamic loads too an increase in stiffness in relation to static loads is achieved. For example, Cylinder tube warping due to the screw forces minimize.

Oxide-ceramic can be used as ceramic materials for the components Materials, especially mixed ceramics or dispersion ceramics based on, for example, aluminum oxide, Silicon oxide or zirconium oxide and / or mixtures of which can be used. In addition, silicon nitrite (Si3) or silicon carbide and generally FRC's (fiber reinforced ceramics). The selection judges in addition to the cost of these materials the respective stress.

Claims (6)

1. A piston engine, in particular a piston internal combustion engine, in which the cylinder, piston, crankshaft and crankshaft bearings are arranged in an engine block (1), with regions of the engine block being covered with cap-like and/or trough-like covers and in which the walls of the cylinder block (2) and/or of the covers are securely connected, at least in partial regions, to rib-like reinforcing components (4;, 12, 13, 14) which are made of a component material which is different from the basic material of the engine block (1) and/or of the covers, which has a higher elasticity modulus than the basic material.
2. A piston engine according to Claim 1, characterised in that the component material consists of a ceramic material.
3. A piston engine according to Claim 1 or 2, characterised in that the components (4; 12, 13, 14) are each surrounded positively by basic material, at least in part.
4. A piston engine according to one of Claims 1 to 3, characterised in that the reinforcing components in the region of the crankshaft bearings (8) are in the form of crosspiece-like ribs (12, 13, 14) and connect the bearing region to the walls of the engine block (1) or of the crankcase (3).
5. A piston engine according to one of Claims 1 to 4, characterised in that the reinforcing components (4; 12, 13, 14) are joined to the basic material by at least partial integral casting therewith.
6. A piston engine according to one of Claims 1 to 4, characterised in that the reinforcing components (4; 12, 13, 14) are securely joined to the basic material by means of auxiliary materials.

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