EP0885354B1 - Crankcase for piston engines, especially v-engines - Google Patents

Description

The invention relates to a machine housing for reciprocating piston machines.

In order to reduce the weight of a machine housing, it is generally known the highly loaded, essentially from the cylinders with direct or indirect formed engine block preferably formed crankshaft bearings Manufacture from iron material, and the less stressed housing walls separately made of a lighter or particularly thin-walled material to train.

An example of this construction principle for the machine housing of a liquid-cooled Internal combustion engine is known from GB-PS 678 903, the Crank chamber bounding housing walls as well as those for covering the cylinder coolant spaces serving housing walls are made of sheet metal. In contrast the engine block is relative to achieve the required strength solidly formed with end walls between the top and bottom plates the cylinder, with weighted storage chairs arranged in one piece on the base plate are.  

Disadvantages of this known machine housing as well as one from the GB-PS 695 972 known housing are each a moderate weight reduction as well Corrosion and sealing problems especially in the joints of the Assemblies made of different materials. There are also acoustic problems.

To reduce the acoustic problems in particular, US Pat. No. 4,446,827 describes Machine housing for a liquid-cooled internal combustion engine known one of the aforementioned GB-PS 678 903 correspondingly massive engine block includes the separate housing walls made of a highly damping Material such as rubber, plastic or resin are assigned.

Corrosion and sealing problems for a made from different materials Machine housings of a liquid-cooled internal combustion engine are in accordance with the German utility model DE-U 94 12 637 avoided in that a Engine block made of cast iron is encased in a light metal housing is, the coolant spaces are formed exclusively in the light metal housing are. The disadvantage here is the massive design of the engine block with the Crankshaft bearings arranged over web-shaped supports Motor skirting boards that are in the oil pan connection area of the light metal housing this are cohesively connected. With this heavyweight design there is a further disadvantage that they are integral with the storage chairs connected engine baseboards act as structure-borne sound bridges and at least those with them cohesively connected crankcase covers of the light metal housing stimulate acoustically.

Furthermore, EP-A, which was previously published in relation to DE-U 94 12 637 0 554 575 already a machine housing for a liquid-cooled internal combustion engine known, in which also an engine block made of cast iron in a light metal housing is cast in. To reduce the weight of the engine block cylinders arranged in series are arranged cohesively adjacent and carry arranged in the connection areas over spaced flat webs, massive storage chairs. Flat webs and storage chairs are used by   Pour into the light metal housing in transverse walls connected to it integrally integrated. This, too, designed for strength reasons, material-intensive Support of the crankshaft bearings against a crankcase housing wall acts as the light metal housing acoustically stimulating structure-borne sound bridge.

Finally, Japanese Patent Laid-Open 4-121 443 for a liquid-cooled Internal combustion engine an engine block with a molded cylinder head known. This design, known as the "monoblock", includes one at the bottom of the cylinder liners formed bottom plate, on the one hand the Monoblock enclosing casing is releasably attached and on the other hand massive crankshaft bearings are arranged, the bearing cover over longitudinal webs in a disadvantageously designed storage frame are arranged.

In the prior art shown above is a common feature recognizable that the bending and torsional stiffness required for an engine block is achieved primarily via interconnected cylinders, namely either via their Siamese arrangement or their arrangement between one-piece material connected top and bottom flange plates the additionally are connected via end plates. A particularly stiff one, but instead of that the cover flange plate provided, arranged integrally and integrally Cylinder head also heavyweight engine block with a solid bearing frame for the bearing cap of the crankshaft bearing shows the generic type mentioned above Japanese Patent Disclosure 4-121,443.

The invention is based, for a lightweight machine housing the task a lightweight engine block with high cylinders, through the cylinders to show insignificantly increased design strength.

The basic idea of the invention is devices arranged in the longitudinal direction of the machine of the engine block as large as possible relative to the crankshaft axis of rotation spaced in a bandage to achieve a high moment of inertia and   to arrange a high section modulus, the necessary for this effective distances on the one hand with the design of the bearing frame at least one stiffening element provided particularly deeply below the crankshaft and on the other hand by an advantageously simple in the direction of the vertical axis of the cylinder or cylinders from the crankshaft axis of rotation far away displaced flange plate are achieved. By using the invention the stiffening element of the bearing frame integrated into a bandage Flange plate eliminates the cylinder as an essential element imparting strength, whereby the cylinder or cylinders can advantageously be made thin-walled.

The piston stroke and cylinder diameter can also be taken into account with the invention to be determined on the structural strength of the engine block with the advantage that even large-volume, powerful reciprocating engines relatively low construction can be carried out. Regarding a lightweight engine block offers the invention with the free choice of the largest possible distances longitudinal machine Devices from the plane of the crankshaft axis of rotation the advantage of a relatively thin-walled design of these devices (Flange plate, stiffening elements) with high strength.

Advantageous embodiments of the machine housing according to the invention are shown in the claims 2 to 12 specified with the aim of one-piece material interconnected open and hollow profiles for both the preferred engine block made from a cast iron as well as for the Housing walls one-piece casing made of a light metal each with a small Material expenditure a high structural strength of both assemblies individually and to achieve in a functional connection.

Figur 1

Für einen V-Motor einen Triebwerksblock in perspektivischer Ansicht mit teilweise gezeigter Ummantelung,

Figur 2

Triebwerksblock und Ummantelung im Querschnitt gemäß der Linie 2-2 in Figur 1.

The invention is described with reference to a preferred example shown in the drawing. It shows:

Figure 1

For a V-engine, an engine block in a perspective view with the casing partially shown,

Figure 2

Engine block and casing in cross section according to line 2-2 in Figure 1.

A machine housing 1 for a liquid-cooled reciprocating piston internal combustion engine designed as a V-engine 2 comprises an engine block 3 and one opposite separate casing 4 formed in one piece from housing walls a material lighter than that of the engine block 3. For connection with the casing 4, the engine block 3 is equipped with flange plates 5, each with cylinders 6 on the one hand and split crankshaft bearings on the other 7 are connected, the bearing cover 8 thereof in a bearing frame 9 are arranged with machine longitudinal stiffening elements 10.

To achieve a lightweight engine block 3 with high bending and torsional rigidity according to the invention, the flange plates 5 are relative to the cylinders 6 from their lower ends to their upper ends offset with their respective Center of gravity seen on the face at intervals on this side of the bearing center plane 11 of the crankshaft bearings 7 arranged, these distances at least greatest possible distances between the centroids of the profiles of the stiffening elements 10 correspond to the bearing frame beyond the center plane 11 of the bearing, and wherein the crankshaft bearings 7 via struts 12 with the flange plates 5th are connected.

The engine block 3 designed according to the invention forms a spatial association, the bending and torsional resistance moments advantageously without Integration of the cylinders 6 essentially via that of the bearing center plane 11 in each case the largest possible spaced machine-oriented devices of the Flange plate 5 in combination with the stiffening elements 10 of the bearing frame 9 are achieved.

A low weight with high rigidity is in a further embodiment according to the invention thereby achieved that the crankshaft bearings 7 each on both sides in   hollow struts 13 arranged essentially in a machine transverse plane with the Flange plates 5 are integrally connected, each preferably bearing ring 7 'designed like a ring by means of radial flanges 14 a cylindrical or U-profile on the flange plate side forms with the hollow struts 13 in the connection area stiffening transitions 15.

Next is for a stiffness with low weight by using one by an oil pan not shown given space provided that each bearing cap 7 "or 8 mutually spaced in the machine longitudinal direction, relative to the bearing center plane 11 laterally deep downward extensions 16, the relatively thin-walled extensions 16 by means of covers 17 form essentially closed hollow profiles 18, which with Cross section adapted to the extensions 16 triangular, thin-walled Hollow beams 19 are connected as stiffening elements 10.

The engine block 3 is preferably at least in the circumference of the flange plates 5 with the crankshaft bearings 7 arranged over the hollow struts 13 inclusive of the bearing frame 9 in one piece, integrally made of vermicular gray cast iron (GGV) manufactured. To divide the crankshaft bearing 7, the bearing frame 9 with the Bearing caps 7 ", preferably by means of break separation from the storage chairs 7 ', the breakage separation in the German patent application P 195 47 389 proposed processes for the formation of break separation notches especially in combination with one of the PCT / EP in the PCT application 95/00875 proposed device is used.

The bearing frame 9 separated from the engine block 3 by "cracking" is also included this by means of two crankshaft bearings 7 provided in the hollow struts 13 screw-in screw 20 connectable. The preferably in the V angle of V-engine 2 essentially arranged bolts 20 preferably pass through fracture separating surfaces arranged obliquely in the center plane 11 of the bearing, with which the lateral forces in each crankshaft bearing 7 over the braced Fracture separating surfaces securely with only two bolts 20 provided   are transferred. This reduced screwing effort results in an advantageous Way a narrow bearing frame with deep below the center of the bearing 11 stiffening elements 10 or hollow beams 19 that can be arranged.

As can be seen from the figures, the roof-like flange plates are arranged 5 over their outer longitudinal areas with the crankshaft bearings 7 over accordingly the bolt 20 V-shaped hollow struts 13 in one-piece material Connection. Between the advantageously to the axes of the Cylinder 6 are arranged essentially parallel hollow struts 13 in the middle flange plates 5 connected in one piece additionally via this connection area by means of hollow supports 21 with each bearing chair 7 'in connection. These supports 21 are used for power dissipation in the vertical axis of the V-engine 2 to avoid a buckling load on the hollow struts 13. To stiffen the connection area the flange plates 5, a longitudinal channel 22 is provided, for example in cooperation with the hollow supports 21 of the lubricating oil supply to the bearings 7 is used.

As already mentioned earlier, the invention is without the cylinders 6 Engine block 3 as a spatial association of high bending and torsional rigidity achieved. This can be used either with the respective or depending on the need Flange plate 5 fixed cylinder 6 can be selected. In the latter In this case, the flange plates 5 preferably pass obliquely Achieving a stiffer connection between the respective cylinder 6 and Flange plate 5 against operating vibrations, which are additionally spaced in series Cylinders 6 between bridges 23 arranged in the row direction between the cylinders 6 are reduced. Next, the cylinders 6 are without casting an additional Material free in the respective coolant.

For a permanent connection of the engine block 3 with the one-piece casing 4 have the flange plates 5 in the machine longitudinal and transverse directions in each case by means of large radii cambered edges 24 on the machine housing corners merge into other, smaller radii. They are further   Edges 24 e.g. designed as T-shaped flanges 25 in cross section. Alternatively to the Flanges 25, the edges 24 can also have a rough surface for positive and non-positive connection with the light metal casing 4. Furthermore, the flanges 25 can also have a rough surface.

With this configuration of the edges 24 on the flange plates 5, the engine block can 3 one made of outer and inner longitudinal and front housing walls assigned one-piece casing 4 from a light metal casting be, which when cooling in the shrinking through the flange 5 of the Engine block 3 handicapped light metal casing 4 over the convex Edges 24 uniformly form-fit and non-positively with the flanges 25 of the Flange plates 5 is connected liquid-tight.

The casing 4 is further advantageously stiffened in that the Flange plates 5 cylinders 6 integrally connected by a material fit, each in one with coolant openings 26 provided cold room cover plate 27 which with the casing 4 in one-piece material connection.

For further stiffening of the casing 4 and thus the machine housing 1 form inner longitudinal housing walls 28 with floor space crossing the V space and top walls 29 and 30 a hollow beam stiffening the rows of cylinders 6 31, which as a coolant channel with a e.g. pump housing arranged at the front 32 between integral valve train shafts in connection stands (Figure 2).

To achieve a lightweight casing 4 it is also provided that this between an oil pan flange provided in the area of the bearing center plane 11 33 and the connection to the flanges 25 of the flange plates 5 Connection points 34 for ancillaries and / or support brackets via adjacent hollow struts 13 arranged pins 35 are connected preferably serve the arrangement of screw points.  

In order to keep larger loads away from the light metal casing 4, this is covered engine block 3 on the output side a separate connecting flange 36 assigned for a transmission, not shown, in the middle and in both Outside areas of the flange plate 5 above the crankshaft bearing on the output side 7 and with the bearing frame 9 in the region of the hollow beams 19 below this Bearing 7 each with screw 37 with the engine block 3rd is connectable.

The weight advantage achievable with the invention comes in particular in the case of multi-cylinder V-type reciprocating machines are particularly useful, but can can also be advantageous for single-row machines with one or more cylinders.

Claims (14)

1. A casing for reciprocating-piston engines,

   comprising an engine block (3) for connecting to a separate cylinder head and provided with separate casing walls of a shell (4) of different material,

   wherein the engine block (3) comprises a flange plate (5) for bearing a cylinder (6) and for connecting the casing walls and divided crankshaft bearings (7),

   the bearing covers (8 or 7") whereof are disposed in a bearing frame (9) comprising at least one reinforcing element (10) in the longitudinal direction of the engine,

   wherein the crankshaft bearings (7) are connected to the flange plate (5) via struts (12 or 13) engaging the flange plate (5) separately from the cylinder (6),

   and the flange plate (5) is constructed as a bearing element for a cylinder (6) and is offset from the bottom end thereof to the top end in such a manner that

   a maximum spacing is obtained between the centroid of the flange plate (5), as seen from the end face, and the central plane (11) of the crankshaft bearings (7),

   equal at least to a spacing between the bearing centre plane (11) and a centroid, as seen from the end face, of a profile of the reinforcing element (10) of the bearing frame (9).
2. An engine casing according to claim 1, characterised in that

   each bearing (7) is connected integrally and via the material to the flange plate (5) via hollow struts (13) disposed on each side substantially in a transverse plane of the engine, and

   each semi-annular bearing block (7') has radial flanges (14) forming a U-profile open on the same side as the flange plates, in conjunction with transition members (15) which reinforce the hollow struts (13), at least in part.
3. An engine casing according to claim 1 or claim 2, characterised in that

   each bearing cover (7") has spaced-apart extensions (16) directed downwards and sideways relative to the bearing centre plane (11), and

   the relatively thin-walled extensions (16) have covers (17) forming substantially closed hollow profiles (18), which

   are connected to reinforcing elements (10) in the form of thin-walled hollow means (19) substantially triangular in cross-section.
4. An engine casing according to claims 1 to 3, characterised in that

   the flange plate (5) is made of cast iron integrally with the crankshaft bearings (7) disposed over the hollow struts (13), including the bearing frame (9), and

   the bearing frame (9) and the bearing covers (7") are separated from the bearing blocks (7') by fracture separation and

   can be connected to the engine block (3) via two screw bolts (20) per crankshaft bearing (7), for screwing into the hollow struts (13).
5. An engine casing according to claims 1 to 4, characterised in that

   in the case of a V-engine (2), flange plates (5) disposed in a roof shape are centrally connected in one piece, and

   are connected via the said connecting region to each bearing block (7') via hollow supports (21), and

   each crankshaft bearing (7) is integrally connected via the material to outer longitudinal regions of the flange plates (5) near the flange, via two hollow struts (13) disposed in a V-shape in a transverse plane of the engine.
6. An engine casing according to claim 5, characterised in that

   the flange plates (5) are connected centrally via a longitudinal duct (22), which

   in co-operation with the hollow supports (21) is of use for supplying lubricating oil to the crankshaft bearings (7).
7. An engine casing according to claims 5 and 6, characterised in that

   the flange plates (5) disposed in a roof shape are connected integrally and via the material to the respective cylinders (6) in each row, which extend obliquely through the flange plates, and

   cylinders (6) spaced apart in a row are connected together via bridges (23) disposed in the direction of the row.
8. An engine casing according to claims 5 to 7, characterised in that

   the connected flange plates (5) have respective bulging edges (24) with large radii in the longitudinal and transverse direction of the engine and

   connected to the corners of the engine casing via additional radii, wherein

   the edges (24) are in the form of flanges (25) having a T-shaped cross-section.
9. An engine casing according to claims 5 to 8, characterised in that

   a light-metal shell (4) in one piece comprising outer and inner longitudinal and end-face casing walls is connected positively and non-positively in liquid-tight manner to the flanges (25) of the flange plates (5) by casting, and

   the cylinders (6) in the flange plates (5) each end in a cooling-chamber cover plate (27) connected in one piece and by the material to the light-metal shell (4) and optionally formed with coolant apertures (26).
10. An engine casing according to claims 5 to 9, characterised in that surfaces connecting the edges (24) and/or the flanges (25) of the flange plates (5) to the light-metal shell (4) have a rough fractured exterior.
11. An engine casing according to claims 5 to 10, characterised in that

    the inner longitudinal casing walls (28) co-operate with bottom and top walls (29, 30) extending transversely through the V-space to form a hollow support (31) which reinforces the rows of cylinders (6), and which

    is in the form of a coolant duct connected to a pump casing (32) disposed at the endface between valve drive shafts integrally moulded in one piece.
12. An engine casing according to claims 5 to 11, characterised in that on the shell (4), connecting places (34) for subsidiary units and/or bearing supports, provided between an oil-sump flange (33) in the neighbourhood of the bearing central plane (11) and the flange connection comprising the flange plates (5) are connected via journals (35) disposed on neighbouring hollow struts (13).
13. An engine casing according to claims 5 to 12, characterised in that

    a separate connecting flange (36) is associated with the shell-encased engine block (3) on the power take-off side, and

    can be connected in the centre region and in the two outer regions of the flange plates (5) above the crankshaft bearing (7) on the power take-off side and

    to the bearing frame (9) in the region of the hollow beam (19) below the said bearing (7) to the engine block (3) via respective screw connections (37).
14. An engine casing according to claims 5 to 13, characterised in that the cylinders (6) are free from embedding in an additional material and are disposed so that their external peripheries are acted upon by a coolant, especially for the reciprocating-piston engine (2).