Europäisches Patentamt *EP000987426B1* (19) European Patent Office

Office européen des brevets (11) EP 0 987 426 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.7: F02F 7/00, F16C 9/02 of the grant of the patent: 10.12.2003 Bulletin 2003/50

(21) Application number: 99118234.6

(22) Date of filing: 14.09.1999

(54) block bearing saddle reinforcing insert and engine block Maschinengestell und Lagersattelverstärkungseinsatz Bloc moteur avec siege renforcé pour des paliers

(84) Designated Contracting States: • Yong Ching Chen DE GB IT Indiana 47203 (US) • Becker, Paul C. (30) Priority: 15.09.1998 US 153460 Indiana 47401 (US) • Belush, Richard (43) Date of publication of application: Indiana 47201 (US) 22.03.2000 Bulletin 2000/12 (74) Representative: Gesthuysen, von Rohr & Eggert (73) Proprietor: Cummins Inc. Patentanwälte Columbus, IN 47201 (US) Postfach 10 13 54 45013 Essen (DE) (72) Inventors: • Warwick, Michael J. (56) References cited: Colombus Indiana 47201 (US) EP-A- 0 767 315 US-A- 4 643 145 • Myers, Martin R. US-A- 5 333 668 US-A- 5 816 710 Colombus Indiana 47201 (US)

Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 0 987 426 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 0 987 426 B1 2

Description . The ferrous reinforcements are cast into the aluminum block and mechanically held in place by the [0001] This invention relates to an engine block with aluminum casting. The ferrous reinforcement and the a reinforcing insert for positioning in a bearing saddle aluminum block are chosen to have substantially equal region of the engine block which effectively increases 5 coefficients of thermal expansion thereby overcoming the strength and fatigue resistance of the block while problems caused by differential expansion. However, reducing the overall strain in the bearing. requiring substantially equal coefficients of thermal ex- [0002] Heavy duty diesel generate high cyl- pansion limits the possibilities available for the material inder pressures which create a large amount of strain in used for the ferrous reinforcement. Further, the mechan- the engine block during the power of the . 10 ical connection between the reinforcements and the alu- This strain induces bending loads on the crankshaft con- minum will inherently contain distinct interfacial discon- nected to the and, in turn, the crankshaft bear- tinuity between the surfaces. The heavy loads imposed ings. Typically, engine blocks are formed of a ferrous on the reinforcements from the bearing cap bolts tend material, such as , capable of withstanding the to increase the discontinuities between the surfaces pressure induced strains. However, engine blocks may 15 causing the mechanical bond between the reinforce- also be formed of a low density material, such as an alu- ment and the aluminum block to weaken. minum alloy, instead of cast iron, to advantageously in- [0005] US - A - 5,501,529 discloses another ferrous crease the power density, i.e. horsepower produced per insert positioned within the bearing saddle area of an pound of engine weight. Aluminum or aluminum alloys, aluminum engine block to support the crankshaft bear- while having the advantage of being light in weight, have 20 ing, where the cap is attached to the fer- the disadvantage of possessing less strength than cast rous insert by main bearing cap bolts which engage the iron. In addition, aluminum alloy has a relatively low insert. The ferrous insert is placed into a mold for casting modulus of elasticity, i.e. less stiffness, compared to the engine block and molten aluminum is poured around cast iron, disadvantageously resulting in excessive de- the ferrous insert. A ferrous powder is used to form the flection and increased strain. The increased strain has 25 ferrous insert so that its surface is not fully dense, allow- been found to result in unacceptably high bending loads ing the molten aluminum to flow into the holes in the on the crankshaft and associated bearings. Moreover, structure of the insert to secure the insert to the engine under certain high load applications, cast iron blocks block. However, this method of attaching the ferrous in- have been found to undergo unacceptable deflection. sert to the aluminum engine block forms a mechanical [0003] Additionally, the loads imposed on the - 30 bond between the ferrous insert and the engine block shaft during the power stroke are, in turn, transferred to similar to the bond formed in US - A - 4,643,145. Again, the main bearing caps which secure the crankshaft this type of mechanical bond has a tendency to weaken against the engine block. The main bearing caps are when exposed to the heavy loads imposed on the in- typically bolted to the engine block through threaded serts from the bearing cap bolts. portions formed in the bearing saddle. The forces im- 35 [0006] Another type of bearing saddle reinforcement posed on the main bearing caps can be great enough is disclosed in US-A-5,370,087, where a composite to generate fatigue cracks in the threaded portion of the engine including a molded formed of a light- bearing saddles possibly resulting in failure of the en- weight composite material is interconnected with a me- gine, especially when the threads are formed in an alu- tallic bearing insert. The metallic insert is attached to a minum engine block or other low density material. Thus, 40 bearing cap so that the crankshaft bearings contact the in heavy duty diesel engines having high assembly metallic insert. However, manufacturing tolerances loads in fastening the main bearing cap to the engine make it difficult for the metallic insert to be attached to block as well as large amount of stress at the threaded the molded crankcase and precisely aligned with the capscrew connection of the main bearing to the block bearing cap for engagement with the bearings. There- during power strokes, it is undesirable to have an alu- 45 fore, an unnecessarily high degree of precision is re- minum alloy present in the bearing saddle area where quired when forming the molded crankcase around the the capscrew holes are formed. Moreover, there is still insert to ensure proper alignment of the metallic insert a need for improving the stress resistance of cast iron with the bearing cap and bearings. blocks. [0007] There have also been attempts to improve the [0004] In order to increase the strength of the thread- 50 bond between metallic inserts and engine blocks to cre- ed holes in an engine block, there have been attempts ate greater structural integrity. For instance, US - A- at positioning hardened reinforcements in the bearing 5,333,668 discloses a process for metallurgically bond- saddle area to provide a more secure anchor for the ing an engine liner insert to an aluminum engine main bearing capscrews. US - A-4,643,145 discloses block cast around the insert, where the insert is coated one such method of reinforcement which includes fer- 55 with a metallic bonding material, such as zinc, prior to rous reinforcements having threaded bosses for receiv- casting the aluminum engine block. The molten alumi- ing crankshaft bearing cap bolts so as to resist damage num material then metallurgically bonds to the bonding to the threads and mitigate forces caused by the engine material coating the insert. US - A - 5,333,668 forms the

2 3 EP 0 987 426 B1 4 metallurgical bond between the cylinder liner insert and planatory purpose; the engine block in order to provide a more continuous bond, thereby allowing for more effective heat transfer Fig. 2 a cross-sectional view of the engine block and from the cylinder liner insert to the engine block. More- reinforcing insert of Figure 1 having a main over, cylinder liner inserts are utilized to provide resist- 5 bearing cap attached thereto; ance to wear within the cylinder of an aluminum engine block, but are not subjected to large vertical loads such Fig. 3 a cross-sectional view of an engine block hav- as experienced in the bearing saddle region of the en- ing a monolithic reinforcing insert positioned gine block in a heavy duty . within the bearing saddle region thereof for ex- [0008] In view of the foregoing, there is clearly a need 10 planatory purpose; for a reinforcement positioned within the bearing saddle area of an engine block having an improved bond be- Fig. 4 a cross-sectional view of an engine block hav- tween the reinforcement and the engine block capable ing a multiple reinforcing inserts positioned of maintaining the bond at high engine loads. Further, within the bearing saddle region thereof in ac- there is a need for a hardened reinforcement having this 15 cordance with the present invention; and improved bond which allows an engine block to be se- lectively reinforced in highly stressed areas, of the main Fig. 5 a cross-sectional view of an alternative em- bearing saddle region of the engine block. bodiment of an engine block and reinforcing in- [0009] It is an object of the present invention to over- sert of Fig. 4. come the aforementioned shortcomings associated with 20 the prior art, in particular to provide an engine block with [0013] Here, the terms "upper" and "lower" refer to an an improved bearing saddle reinforcing insert for an en- orientation of an engine block as shown in Fig. 1, where gine block which is selectively positioned to reinforce the saddle area for receiving a crankshaft opens down- highly stressed areas of the bearing saddle region of the wardly; i. e. a lower surface contacts the crankshaft or engine block and to provide an engine block having re- 25 its bearing shell. inforced bearing saddle areas which is relatively inex- [0014] Referring now to Figure 1, an engine block 10 pensive and simple to manufacture. is illustrated having a reinforcing insert 12 positioned [0010] The above object is achieved by an engine within the crankshaft bearing saddle region of one trans- block according to claim 1. Preferred embodiments are verse wall, or scantling 13, of the engine block 10. The subject of the subclaims. 30 engine block 10 will typically include a plurality of trans- [0011] Preferably, a plurality of cylindrical reinforcing verse walls, each having a bearing saddle region, posi- inserts is positioned within bores formed in the bearing tioned at spaced locations along the length of a crank- saddle area of the engine block. Each of the cylindrical shaft supported by the block. Although only one trans- reinforcing inserts are positioned within a respective verse wall 13 is shown, it should be understood that the formed within the engine block and extending up- 35 insert designs of the present invention may be applied wardly from a portion of the engine block which engages to the bearing saddle regions of any or all of the trans- the main bearing cap. The inserts are formed separately verse walls of an engine block. and a portion of the engine block extends between the [0015] The reinforcing insert 12 is formed of a high cylindrical reinforcing inserts and the main bearing shell strength, fatigue resistant material in order to selectively surrounding the crankshaft. The cylindrical reinforcing 40 increase the strength and stiffness of the bearing saddle inserts are coated with a bonding material which is met- region. Since aluminum alloys have a lower modulus of allurgically bonded to engine block. The cylindrical rein- elasticity than cast iron, which has been conventionally forcing inserts extend along axes that are not parallel to used for forming engine block due to its high strength, each other. The cylindrical reinforcing inserts include a engine blocks formed from aluminum alloys tend to pos- threaded aperture for receiving a main bearing cap- 45 sess a greater degree of vertical stretch or displacement screw attaching a main bearing cap to the engine block, during the power stroke within the engine cylinder. wherein the lower surface of the cylindrical reinforcing Moreover, cast iron engine blocks may also experience inserts abuts an adjacent portion of the main bearing unacceptable levels of vertical stretch or may develop cap. This aperture may be machined into the inserts af- fatigue cracks due to excessive stress. Therefore, the ter the inserts have been bonded to the block. These 50 reinforcing insert 12 is formed of a material having a cylindrical inserts may also be cast in place. higher modulus of elasticity than the modulus of the en- [0012] Hereinafter, the present invention is explained gine block material in order to reduce the overall deflec- in more detail, referring to preferred embodiments tion of the engine block as compared to an unreinforced shown in the drawings. It shows: engine block. For example, an aluminum or aluminum 55 alloy engine block may be reinforced with an insert Fig. 1 a cross-sectional view of an engine block hav- formed of steel, stainless steel, gray iron, ductile iron or ing a monolithic reinforcing insert positioned another material having a greater modulus of elasticity within the bearing saddle region thereof for ex- than aluminum, such as a metal matrix composite. Also,

3 5 EP 0 987 426 B1 6 a cast iron engine block may be reinforced with an insert shaft extending beneath the bearing saddle region of the formed of steel, stainless steel or any other material hav- engine block. A portion of the engine block 10 preferably ing a greater modulus of elasticity than gray iron, e.g. a extends between the lower surface 22 of the reinforcing metal alloy. Reducing the deflection of the engine block insert 12 and a main bearing shell 24 surrounding the prevents unacceptable bending loads from being im- 5 crankshaft, as shown in Figure 2. By forming a portion posed on the crankshaft and respective bearings. of the engine block 10 between the lower surface 22 of [0016] The reinforcing insert 12 is positioned within the reinforcing insert 12 and the main bearing shell 24 the engine block 10 adjacent to the location where an and main bearing cap 26, a precise fitting relationship engine crankshaft is secured to the engine block 10. The between the engine block 10 and the other components engine block 10 includes a semi-circular portion 14 10 can consistently be achieved when forming the engine formed therein for accommodating the crankshaft, and block 10 since the mold for the engine block 10 can be the reinforcing insert 12 similarly possesses a semi-cir- precisely formed in a consistent manner. However, it is cular region 16 in the area adjacent to semi-circular por- understood that the reinforcing insert may alternatively tion 14. The reinforcing insert 12 includes opposing lin- be positioned so as to directly abut the main bearing ear side surfaces 18a and 18b which extend along 15 shell 24 to provide additional resistance to wear. Simi- planes that are not parallel to each other. While the re- larly, the reinforcing insert may alternatively be posi- inforcing insert 12 is shown as being positioned beneath tioned so as to directly contact the main bearing cap 26. a cylinder bore 20, the reinforcing insert 12 may be po- [0020] As shown in Figure 2, the reinforcing insert 12 sitioned in any transverse wall 13 within the engine block includes a pair of threaded apertures 28 which are 10 along the length of the crankshaft. 20 formed in the lower surface 22, where the threaded ap- [0017] The reinforcing insert 12 is preferably formed ertures 28 are formed on opposite sides of semi-circular having a complex geometry in order to provide strength region 16. Each of the threaded apertures 28 receives and stiffness in multiple directions. The shape of rein- a main bearing capscrew 30 which attaches the main forcing insert 12 provides optimal strength and stiffness bearing cap 26 to the engine block 10. The main bearing to the engine block in the desired directions to oppose 25 capscrew 30 extends through an aperture 32 formed in the stresses experienced by the engine block 10. The the portion of the engine block 10 beneath the lower sur- linear side surfaces 18a and 18b are angled with respect face 22 of the reinforcing insert 12 and in alignment with to one another, where a width of the reinforcing insert aperture 28. Since the firing load from the power stroke preferably increases as the linear side surfaces 18a and is transferred through the crankshaft to the main bearing 18b extend away from a lower transverse surface 22 in 30 cap 26 and, in turn, to the main bearing capscrews 30, order to resist displacement forces exerted on the rein- it is advantageous for the main bearing capscrews 30 forcing insert 12 in the direction of the lower surface 22 to threadingly engage the reinforcing insert 12 to provide and provide a greater mechanical bond with the engine the necessary high strength and fatigue resistance to block 10. prevent fatigue cracks from initiating in the threading en- [0018] In the embodiment shown in Figure 1 for ex- 35 gagement with the engine block 10. Therein, the threads planatory purpose, the reinforcing insert 12 is formed as in the reinforcing insert 12 provide additional strength to a monolithic piece of material and cast-in-place in the resist being damaged, worn or even stripped and thus bearing saddle region of the engine, where the engine preventing weakening of the connection at the cap- block material is cast around the reinforcing insert 12. screws 30 thereby ensuring secure mounting of main The reinforcing insert may further be coated with a bond- 40 bearing cap 26 and the crankshaft throughout engine ing material, such as zinc, zinc alloys, nickel, silver, cop- operation. per-brazing alloys or any other material capable of form- [0021] The reinforcing insert 12 is shaped to maxi- ing a metallurgical bond with the engine block material mize the reduction of stress in the bearing saddle region as it is cast around the reinforcing insert, in order to fur- of the engine block 10 while also accounting for the var- ther secure the reinforcing insert in its desired position. 45 ying shape of the engine block 10. As shown in Figures As the molten engine block material, i.e. aluminum or 1 and 2, the reinforcing insert 12 is shaped to have an cast iron, is poured into the mold to surround the rein- expanding width as the reinforcing insert 12 extends forcing insert 12, the molten engine block material com- away from lower surface 22, where this shape assists bines with the bonding material coating the reinforcing in preventing the reinforcing insert 12 from being dis- insert 12 to form the metallurgical bond. Furthermore, 50 placed from its position within the engine block 10. Fur- grooves may be formed on the outer surface of the re- thermore, the reinforcing insert 12 includes curved por- inforcing insert 12 to enhance the mechanical bond to tions 34a and 34b which taper the reinforcing insert 12 the engine block, since the molten engine block material as it extends toward an upper surface 36. The curved will fill the grooves as the engine block is cast around portions 34a and 34b are shaped so as to accommodate the reinforcing insert. 55 decreased widths of the engine block 10 and passages [0019] The reinforcing insert 12 includes the lower formed within the engine block 10. transverse surface 22 that extends between the linear [0022] Another reinforcing insert which reduces side surfaces 18a and 18b and adjacent to the crank- stresses in the bearing saddle region of the engine block

4 7 EP 0 987 426 B1 8

10 while forming a strong bond with the engine block 10 block 10 by reducing the overall strain in this region. to resist displacement is shown in Figure 3. The rein- Similar to the above-described embodiments, the cylin- forcing insert 37 is very similar to the reinforcing insert drical reinforcing inserts 40 are formed of a high 12 of the first embodiment except that the insert 37 in- strength, fatigue resistant material having a higher mod- cludes tapering linear side surfaces 38a and 38b which 5 ulus of elasticity than the modulus of the engine block extend from lower surface 22 in a converging manner material in order to reduce the overall deflection of the as opposed to a diverging manner. Thus, the width of engine block as compared to an unreinforced engine the reinforcing insert 12 is decreased as it extends to- block. This embodiment is particularly advantageous in ward upper surface 36, as shown in Figure 3. This "A" that the bearing saddle areas of existing engines can be shape positions the insert material only on those areas 10 retrofit with reinforcing inserts 40. of the bearing saddle most in need of strengthening and [0025] As shown in Figure 4, the cylindrical reinforcing stiffening while providing material for positioning of inserts 40 may be angled with respect to one another in bores 39. As a result, this "A" shape design reduces the order to accommodate the shape of the engine block 10 weight of the engine block relative to the embodiment while having a sufficient length to provide the necessary of Figures 1 and 2. 15 vertical reinforcement. The cylindrical reinforcing inserts [0023] Referring now to Figure 4, a preferred embod- 40 and apertures 42 may also be formed having multiple iment of the present invention is illustrated where the diameters, where a larger diameter portion exists near reinforcing insert includes a plurality of cylindrical rein- the lower surface of the cylindrical reinforcing insert 40, forcing inserts 40 positioned within bores 42 formed in as shown in Figure 5. The larger diameter, d1, provides the bearing saddle area of the engine block 10. Each of 20 a sufficient volume of material to permit the formation of the cylindrical reinforcing inserts 40 are positioned with- apertures 46 and effective support of main bearing cap- in the respective bore 42 formed within the engine block screw 30. The diameter of the cylindrical reinforcing in- 10 extending upwardly from a portion 44 of the engine serts 40 decreases farther from surface 48 to form a block 10 which engages the main bearing cap 26. The smaller diameter portion having a diameter, d2. By form- bores 42 are formed to allow a portion of the engine 25 ing the smaller diameter portion at the upper portion of block 10 to extend between the cylindrical reinforcing the transverse wall 13, the cylindrical reinforcing inserts inserts 40 and the semi-circular portion 14 formed in the 40 can extend a sufficient distance into the block 10 adjacent to the main bearing shell 24. wall 13 to provide the necessary additional vertical stiff- After the engine block 10 is cast, bores 42 are drilled ness and strength without interfering with existing pas- into the engine block 10 and the cylindrical reinforcing 30 sages and shapes designed into the engine block. inserts 40 are positioned within bores 42. Alternatively, bores 42 may be cast into block 10. The cylindrical re- inforcing inserts 40 are coated with a bonding material Claims which forms a metallurgical bond with the engine block material by heating. This secures the reinforcing inserts 35 1. Engine block formed of an engine block material 40 in respective bores 42. The cylindrical reinforcing in- and adapted to support an engine crankshaft ex- serts 40 are each positioned along a central axis extend- tending along a central axis, wherein the engine ing angularly upwardly from a lower surface 48 of the block (10) comprises: insert. Preferably, the inserts 40 extends in a converg- ing, nonparallel manner toward the top of the engine 40 a plurality of transverse walls (13), each of said block. This positioning angle tends to secure the inserts transverse walls (13) including a bearing sad- 40 against loading forces acting downwardly thereby dle area for supporting the crankshaft; preventing damage to or weakening the bond. Each cy- lindrical reinforcing insert 40 includes a threaded aper- a plurality of reinforcing inserts (40) positioned ture 46 for receiving a main bearing capscrew 30 attach- 45 in said bearing saddle area, said plurality of in- ing a main bearing cap 26 to the engine block 10. These serts (40) being formed of a material having a are preferably machined into the inserts after the inserts higher modulus of elasticity than the modulus are bonded in place. The lower surface 48 of each cy- of elasticity of the engine block material and in- lindrical reinforcing insert 40 abuts an adjacent portion cluding a first reinforcing insert (40) positioned of the main bearing cap. In another preferred embodi- 50 on one side of the central axis preferably within ment of the present invention, the cylindrical reinforcing a respective bore (42) formed in said bearing inserts 40 can be cast in place. This eliminates the need saddle area and a second reinforcing insert to drill the bores 42. (40), separate from said first reinforcing insert [0024] The location of the cylindrical reinforcing in- (40), and positioned on an opposite side of the serts 40 optimally reinforces the bearing saddle region 55 central axis preferably within a respective bore of the engine block 10 to provide added vertical stiffness (42) formed in said bearing saddle area, each and strength in this region. The length of the cylindrical of said first and said second reinforcing inserts reinforcing insert 40 reduces deflection of the engine (40) including cylindrical portions metallurgical-

5 9 EP 0 987 426 B1 10

ly bonded to said material of the engine block schnitte aufweist, die metallurgisch an das Ma- (10) and including a threaded aperture (46) for terial des Motorblocks (10) gebunden sind, und receiving a main bearing capscrew (30) which eine Gewindeausnehmung (46) zur Aufnahme attaches a main bearing cap (26) to the engine einer Hauptlagerkappenschraube (30) auf- block (10). 5 weist, die eine Hauptlagerkappe (26) am Mo- torblock (10) befestigt. 2. Engine block according to claim 1, characterized in that said first and said second reinforcing inserts 2. Motorblock nach Anspruch 1, dadurch gekenn- (40) are substantially cylindrically shaped and ex- zeichnet, daß der erste und zweite Verstärkungs- tend along respective axes that are nonparallel to 10 einsatz (40) im wesentlichen zylindrisch geformt each other, preferably wherein said first and said sind und sich entlang jeweiliger Achsen erstrecken, second cylindrically shaped reinforcing inserts (40) die nicht parallel zueinander sind, vorzugsweise include a first cylindrical portion having a first diam- wobei der erste und zweite zylindrisch geformte eter and a second cylindrical portion having a sec- Verstärkungseinsatz (40) einen ersten zylindri- ond diameter smaller than said first diameter. 15 schen Abschnitt mit einem ersten Durchmesser und einem zweiten zylindrischen Abschnitt mit einem 3. Engine block according to claim 1 or 2, character- zweiten Durchmesser, der geringer als der erste ized in that said bearing saddle area includes a Durchmesser ist, aufweisen. lower transverse surface and said first and said sec- ond reinforcing inserts (40) extend convergingly 20 3. Motorblock nach Anspruch 1 oder 2, dadurch ge- away from said lower transverse surface. kennzeichnet, daß der Lagersattelbereich eine un- tere quer verlaufende Oberfläche umfaßt und sich 4. Engine block according to any one of claims 1 to 3, der erste und zweite Verstärkungseinsatz (40) kon- characterized in that said engine block material is vergierend weg von der unteren quer verlaufenden cast iron and said insert material is one of steel, 25 Oberfläche erstrecken. stainless steel and a metal alloy. 4. Motorblock nach einem der Ansprüche 1 bis 3, da- durch gekennzeichnet, daß das Motorblockmate- Patentansprüche rial aus Gußeisen ist und das Einsatzmaterial Stahl, 30 Edelstahl oder eine Metallegierung ist. 1. Motorblock, gebildet aus einem Motorblockmaterial und angepaßt, um eine Motorkurbelwelle entlang einer zentralen Achse zu halten bzw. zu lagern, wo- Revendications bei der Motorblock (10) aufweist: 35 1. Bloc moteur formé d'un matériau de bloc moteur et eine Mehrzahl von Querwänden (13), wobei je- adapté pour supporter un vilebrequin de moteur de der Querwände (13) einen Lagersattelbe- s'étendant le long d'un axe central, dans lequel le reich zur Halterung bzw. Lagerung der Kurbel- bloc moteur (10) est constitué: welle aufweist; 40 d'une pluralité de parois transverses (13), cha- eine Mehrzahl von Verstärkungseinsätzen cune desdites parois transverses (13) compre- (40), angeordnet in dem Lagersattelbereich, nant une zone d'étrier de roulement pour sup- wobei die Mehrzahl von Einsätzen (40) aus ei- porter le vilebrequin; nem Material hergestellt ist, das einen höheren Elastizitätsmodul als der Elastizitätsmodul des 45 d'une pluralité d'inserts de renfort (40) placés Motorblockmaterials aufweist, und umfaßt ei- dans ladite zone d'étrier de roulement, ladite nen ersten Verstärkungseinsatz (40), der auf pluralité d'inserts (40) étant formée d'un maté- einer Seite der zentralen Achse, vorzugsweise riau ayant un module d'élasticité plus élevé que innerhalb einer jeweiligen Bohrung (42), die in le module d'élasticité du matériau du bloc mo- dem Lagersattelbereich gebildet ist, angeord- 50 teur et comprenant un premier insert de renfort net ist, und einen zweiten Verstärkungseinsatz (40) placé sur un côté de l'axe central de pré- (40), der von dem ersten Verstärkungseinsatz férence dans un alésage respectif (42) formé (40) getrennt ist und auf einer gegenüberlie- dans ladite zone d'étrier de roulement et d'un genden Seite der zentralen Achse, vorzugswei- deuxième insert de renfort (40), séparé dudit se innerhalb einer jeweiligen Bohrung (42), die 55 premier insert de renfort (40), et placé sur un in dem Lagersattelbereich gebildet ist, ange- côté opposé de l'axe central de préférence ordnet ist, wobei jeder der ersten und zweiten dans un alésage respectif (42) formé dans la- Verstärkungseinsätze (40) zylindrische Ab- dite zone d'étrier de roulement, chacun dudit

6 11 EP 0 987 426 B1 12

premier et dudit deuxième inserts de renforce- ment (40) comprenant des parties cylindriques reliées métallurgiquement audit matériau du bloc moteur (10) et comprenant une ouverture filetée (46) pour recevoir un palier de vis d'as- 5 semblage (30) qui attache un palier de chapeau (26) au bloc moteur (10).

2. Bloc moteur selon la revendication 1, caractérisé en ce que ledit premier et deuxième inserts de ren- 10 forcement (40) sont de forme sensiblement cylindri- que et s'étendent le long des axes respectifs qui sont non parallèles l'un par rapport à l'autre, de pré- férence dans lequel lesdits premier et deuxième in- serts de renfort de forme cylindrique (40) compren- 15 nent une première partie cylindrique ayant un pre- mier diamètre et une deuxième partie cylindrique ayant un deuxième diamètre plus petit que ledit pre- mier diamètre. 20 3. Bloc moteur selon la revendication 1 ou 2, carac- térisé en ce que ladite zone d'étrier de roulement comprend une surface transverse et lesdits premier et deuxième inserts de renfort (40) s'étendant de façon convergente à l'écart de ladite surface trans- 25 verse inférieure.

4. Bloc moteur selon l'une quelconque des revendica- tions 1 à 3, caractérisé en ce que ledit matériau de bloc moteur est en fonte et ledit matériau d'insert 30 est en acier, en acier trempé et en alliage métalli- que.

35

40

45

50

55

7 EP 0 987 426 B1

8 EP 0 987 426 B1

9 EP 0 987 426 B1

10 EP 0 987 426 B1

11 EP 0 987 426 B1

12