WO2013110470A1

WO2013110470A1 - Multi-joint crank drive of an internal combustion engine, and method for assembling a multi-joint crank drive

Info

Publication number: WO2013110470A1
Application number: PCT/EP2013/000240
Authority: WO
Inventors: Matthias Brendel
Original assignee: Audi Ag
Priority date: 2012-01-27
Filing date: 2013-01-28
Publication date: 2013-08-01
Also published as: DE102012001648B4; DE102012001648A1

Abstract

The invention relates to a multi-joint crank drive (10) of an internal combustion engine (1), comprising a plurality of coupling elements (11) which are rotatably mounted on crankpins (6) of a crankshaft (2) and comprising a plurality of articulated connecting rods (15) which are rotatably mounted on crankpins (19) of an eccentric shaft (8). Each coupling element (11) is pivotally connected to a piston connecting rod (4) of a piston (3) of the internal combustion engine (1) and to one of the articulated connecting rods (15). The eccentric shaft (8) is present as an assembled shaft and has a support pipe (25), at least one crankpin (19) which is eccentric relative to a rotational axis (9) of the eccentric shaft (8) and which is designed separately from the support pipe (25), and at least one transmission element (24) which is designed separately from the support pipe (25). The invention further relates to a method for assembling a multi-joint crank drive (10).

Description

Multi-joint crank drive of an internal combustion engine and method

for mounting a multi-link crank drive

The invention relates to a multi-link crank drive of an internal combustion engine, with a plurality of rotatably mounted on crank pins of a crankshaft coupling links and a plurality of rotatably mounted on crank pin eccentric shaft Anlenkpleueln, each of the coupling links is pivotally connected to a piston connecting rod of a piston of the internal combustion engine and one of the Anlenkpleueln. The invention further relates to a method for assembling a multi-joint crank drive.

The multi-link crank drive of the type mentioned is known from the prior art. It is usually part of the internal combustion engine, but can also be used in other areas. The multi-joint crank drive comprises the eccentric shaft whose rotation angle can be adjusted by means of an adjusting device, in particular as a function of an operating point of the internal combustion engine. Alternatively, the eccentric shaft can also be operatively connected to a crankshaft of the internal combustion engine and in this way be drivable by this. The multi-link crank drive has a number of coupling pistons corresponding to the number of pistons of the internal combustion engine, each of which is rotatably mounted on the corresponding crank pin of the crankshaft and has two arms protruding beyond the crankshaft on opposite sides and each having a pivot joint at its end. One of the pivot joints is used for pivotal connection with the piston connecting rod, which connects one of the pistons of the internal combustion engine via the coupling member with the crankshaft. Another of the pivot joints is used for pivotal connection with the so-called Anlenkpleuel, which is rotatably mounted with its other end on the crank pin of the eccentric shaft.

By means of the multi-joint crank drive, the compression ratio achieved in the cylinder assigned to the respective piston can be set, in particular as a function of the operating point of the internal combustion engine and / or the power stroke. To adjust the compression ratio, the eccentric shaft is brought into a specific, the desired compression ratio corresponding angular position or the phase angle between the eccentric shaft and the crankshaft to a certain value. The well-known multi-joint crank drive has a forged and

BESTÄTSGUÜNÜGSKOPIE subsequently machined eccentric shaft. However, the production of such eccentric shaft is very expensive.

The document EP 1 178 194 A2, for example, discloses the state of the art. This describes an internal combustion engine with a variable compression ratio. To set the compression ratio, an eccentric shaft is provided, which is operatively connected via Anlenkpleuel with rotatably mounted coupling members. On the eccentric shaft side facing each Anlenkpleuels a split connecting rod is provided to allow easy mounting of the respective Anlenkpleuels on the eccentric shaft.

It is therefore an object of the invention to provide a multi-joint crank drive of an internal combustion engine, which does not have the disadvantage mentioned above, but in particular has a simple and inexpensive to produce eccentric shaft.

This is achieved according to the invention with a multi-joint crank mechanism with the features of claim 1. It is provided that the eccentric shaft is present as a built shaft and a support tube, at least one eccentric to an axis of rotation of the eccentric eccentric, formed separately from the support tube crank pin and at least one separately formed from the support tube transmission element. The eccentric shaft is therefore not present as a one-piece element, but is assembled during assembly of the multi-joint crank mechanism of individual parts, wherein the individual parts in particular the support tube, the at least one crank pin and the transmission element comprise. The support tube is preferably a circular cylinder which is circular over its entire length. Separated from this, the crank pin and the transmission element are formed or manufactured. When mounting the multi-joint crank drive so the support tube, the crank pin and the transmission element are provided as separate elements. Only during assembly, the elements are connected and fastened together. Accordingly, the production cost for the eccentric shaft is significantly reduced.

A development of the invention provides that the eccentric shaft has a stop and / or encoder wheel. This is provided as an additional element and can for example form at least one end stop, so that the eccentric shaft can be arranged only under a rotational angle contained in a certain rotation angle range. Likewise, it may be formed as a sender wheel, by means of which the present angle of rotation of the eccentric shaft and / or their speed can be determined.

A development of the invention provides that the Anlenkpleueln each have a Anlenkpleuelauge whose inner wall is directly in sliding contact with the crank pin. The Anlenkpleuelauge surrounds the crank pin in the circumferential direction - relative to a rotation axis of the eccentric shaft - preferably completely. In known multi-link crank drives, the Anlenkpleuelauge usually has a bearing bush and is about this only indirectly with the crank pin in sliding contact. The built eccentric shaft, however, allows the inner wall of the Anlenkpleuelauges can be placed directly on the crank pin, without a lower durability is expected. For example, for this purpose the crank pin can be provided with a coating, in particular DLC coating (diamond-like carbon coating). Such a coating can be applied to a forged eccentric shaft only at great expense and correspondingly high costs. In addition, it may be provided that the inner wall of the Anlenkpleuelauges is solidified by rolling or other suitable method.

A development of the invention provides that the support tube is closed at least on one side with a closure part. As a closure part, for example, serve a sealing plug. The closure member prevents dirt and / or moisture from penetrating into the interior of the support tube and may possibly have a corrosive effect there. It is therefore particularly advantageous if the support tube has on both sides in each case such a closure part and is closed by means of this. If the closure part is designed as a sealing plug, it is pushed into the carrier tube during the assembly of the multi-joint cure drive and is then held in a force-fit manner there.

The invention further relates to a method for assembling a multi-joint crank drive, in particular according to the preceding embodiments, wherein the multi-joint crank drive a plurality of rotatably mounted on crank pin crankshaft coupling members and a plurality of rotatably mounted on crank pin eccentric shaft Anlenkpleueln, each of the coupling members pivotally is connected to a piston connecting rod of a piston of the internal combustion engine and one of the Anlenkpleuel. It is provided that the eccentric shaft in the assembly of the multi-joint crank drive from a support tube, at least one eccentric to a rotational axis of the eccentric shaft, formed separately from the support tube crank pin and at least one formed separately from the support tube gear element is built. The multi-joint crank drive or the eccentric shaft can be developed according to the above statements. The advantages realized in this way have already been discussed above.

A development of the invention provides that the crank pin and the gear element are applied to the support tube and then attached by friction welding, internal high pressure forming or shrinking at this. After applying the additional elements, such as the crank pin and the gear element, but for example, the stop and / or encoder wheel, they are attached to the support tube. For this purpose, in particular a welding method, such as friction welding serve. Alternatively, however, the support tube can be widened by forming, so that the elements are subsequently held securely to him. Here, for example, hydroforming is used. Likewise, the elements can be secured by shrinking on the support tube. In this case, the support tube is usually cooled and the, for example, held by a device arranged for this, elements attached to the support tube. In a subsequent heating of the support tube to ambient temperature, this widens, so that the elements are held securely. Alternatively, during shrinkage, the additional elements and not the support tube may be deformed.

It is of course of particular advantage when the crank pins are subjected to a coating process during their manufacture or assembly of the multi-link crank drive with their outer surface in contact contact or sliding contact after assembly with the inner wall of the Anlenkpleuelauges. In this, a coating, such as a DLC coating, are applied. Preferably, a plurality of crank pins are made from a Hubzapfenrohling. Before the Hubzapfenrohling is divided by a separation process in several Hubzapfen, the above-mentioned coating can be applied to him. In that regard, not every single crank pin must be provided separately with the coating.

The invention will be explained in more detail with reference to the embodiments illustrated in the drawings, without any limitation of the invention. Showing:

Figure 1 is a perspective view of a portion of an internal combustion engine, and 2 shows a longitudinal section through an eccentric shaft.

1 shows a perspective view of a portion of an internal combustion engine 1, which as a series internal combustion engine, more specifically as a four-stroke four-cylinder in-line engine is present. The internal combustion engine 1 has a crankshaft 2 and four pistons 3, each of which is movably mounted in one of four cylinders, not shown, of the internal combustion engine 1. Each of the four pistons 3 is connected to the crankshaft 2 by a piston connecting rod 4. The crankshaft 2 is rotatably mounted in shaft bearings (not shown) of a cylinder crankcase of the internal combustion engine 1 also not shown and has five serving for storage centric shaft journal 5 and four crank pin 6 (of which in the figure only one is visible), whose longitudinal center axes in different Angle alignments are offset parallel to a rotation axis 7 of the crankshaft 2.

The internal combustion engine 1 further comprises an eccentric shaft 8, which preferably has an axis of rotation 7 parallel to the axis of rotation 7 of the crankshaft 2. The eccentric shaft 8 is rotatably mounted, for example, next to the crankshaft 2 and slightly below this in the cylinder crankcase and coupled to the crankshaft 2. In addition to the crankshaft 2 and the eccentric shaft 8, the multi-joint crank eb 10 comprises a total of four coupling members 11, which are each rotatably mounted on one of the crank pin 6 of the crankshaft 2. Each of the coupling members 11 has a lifting arm 12, which is connected via a pivot joint 13 pivotally connected to a lower end of one of Kolbenpleuel 4. An upper end of the respective Kolbenpleuels 4 is articulated via a further pivot joint 14 on the associated piston 3. Overall, therefore, each of the four pistons 3 is connected to the crankshaft 2 by the respective piston connecting rod 4 and the respective coupling member 11.

The ehrgelenkskurbeltrieb 10 further comprises a number of Kolbenpleuel 4 and the coupling members 11 corresponding number of Anlenkpleueln 15. These are, for example, approximately parallel to the Kolbenpleueln 4 aligned and in the axial direction of the crankshaft 2 and the eccentric shaft 8 in each case approximately the same plane as the associated Kolbenpleuel 4, but arranged on the opposite side of the crankshaft 2. Each Anlenkpleuel 15 comprises a connecting rod 16 and two at opposite ends of the connecting rod 16 arranged connecting rod eyes 17, 18, in particular with different inner diameters. The larger connecting rod 18 of each Anlenkpleuels 15 at the lower end of the connecting rod 16 surrounds a relative to the axis of rotation 9 of the eccentric shaft 8 eccentric crank pin 19 of the eccentric shaft 8, on the Anlenkpleuel 15 is rotatably supported by means of a rotary bearing 20. The smaller connecting rod eye 17 at the upper end of the connecting rod 16 of each Anlenkpleuels 15 forms part of a pivot joint 21 between the Anlenkpleuel 15 and a longer coupling arm 22 of the adjacent coupling member 11, which protrudes on the opposite to the lifting arm 12 side of the crankshaft 2 on this.

The eccentric shaft 8 has between adjacent eccentric crank pin 19 and at their ends for supporting the eccentric shaft 8 in shaft bearings serving, to the axis of rotation 10 coaxial shaft sections 23. Apart from a variable compression can be reduced by the arrangement described above, the inclination of the Kolbenpleueln 4 with respect to the cylinder axis of the associated cylinder during rotation of the crankshaft 2, resulting in a reduction of the piston side forces and thus the frictional forces between the piston 2 and cylinder walls of the Cylinder leads. Overall, with the multi-link crank drive described here, a working stroke of the pistons 3 can be selected or set as a function of a momentary power stroke of the internal combustion engine. For this purpose, the eccentric shaft 8 is driven by a not shown here eccentric shaft gear from the crankshaft 2. The eccentric shaft gear comprises at least one gear element 2 (not shown) arranged on the eccentric shaft 8.

FIG. 2 shows a longitudinal section through the eccentric shaft 8. It becomes clear that the latter is in the form of a built-up shaft and comprises at least one support tube 25, which is of hollow cylindrical construction, the crank pin 19 and the gear element 24, which is for example in the form of a toothed wheel. In addition, a stop and / or encoder wheel 26 may be arranged on the carrier tube 25. The shaft sections 23, which serve as bearings, are merely indicated here. FIG. 2 shows that a cavity 27 present in the carrier tube 25 is closed by means of closure parts 28 present on both sides of the carrier tube 25. The closure parts 28 are designed in particular as sealing plugs, that is to say they are introduced into the carrier tube 25 when the multi-joint cure drive 10 or the internal combustion engine 1 is mounted in such a way that they are subsequently held in a non-positive manner in the latter. To produce the eccentric shaft 8, the elements shown here, such as the crank pins 19, the gear element 24 and the stop and / or encoder wheel 26 are applied to the carrier tube 25 and then attached thereto, for example by friction welding, hydroforming or shrinking. In principle, however, the attachment can be realized in any manner. The presented here eccentric shaft 8 means a respect to conventional eccentric waves significantly reduced Hersteilungs- and thus cost.

LIST OF REFERENCE NUMBERS

Internal combustion engine

crankshaft

piston

Kolbenpleuel

shaft journal

crank pins

axis of rotation

eccentric shaft

axis of rotation

Multi-joint crank drive

coupling member

lifting arm

pivot

articulation connecting rod

connecting rod

crank pins

pivot bearing

pivot

coupling arm

shaft section

gear element

support tube

Stop and / or encoder wheel

cavity

closing part

Claims

P AT EN TA NSPR O CHE

1. ehrgelenkskurbeltrieb (10) an internal combustion engine (1), with a plurality of rotatably mounted on crank pin (6) of a crankshaft (2) mounted coupling members (11) and a plurality of rotatably mounted on crank pins (19) of an eccentric shaft (8) Anlenkpleueln ( 15), wherein each of the coupling members (11) is pivotally connected to a Kolbenpleuel (4) of a piston (3) of the internal combustion engine (1) and one of the Anlenkpleuel (15), characterized in that the eccentric shaft (8) is present as a built shaft and a support tube (25), at least one to a rotation axis (9) of the eccentric shaft (8) formed separately from the support tube (25) Hubzapfen (19) and at least one separate from the support tube (25) formed gear element (24) ,

2. multi-link crank drive according to claim 1, characterized in that the eccentric shaft (8) has a stop and / or encoder wheel (26).

3. Multi-link crank drive according to one of the preceding claims, characterized in that the Anlenkpleuel (15) each have a Anlenkpleuelauge (18) whose inner wall is directly in sliding contact with the crank pin (19).

4. Multi-link crank drive according to one of the preceding claims, characterized in that the carrier tube (25) is closed at least on one side with a closure part (28).

5. A method for assembling a multi-joint crank drive (10) of an internal combustion engine (1), in particular according to one or more of the preceding claims, wherein the multi-joint crank drive (10) has a plurality of coupling elements (11) rotatably mounted on crank pins (6) of a crankshaft (2). and a plurality of pivotable on crank pin (19) of an eccentric shaft (8) mounted Anlenkpleueln (15), wherein each of the coupling members (11) pivotally connected to a Kolbenpleuel (4) of a Piston (3) of the internal combustion engine (1) and one of the Anlenkpleuel (15) is connected, characterized in that the eccentric shaft (8) during assembly of the multi-joint crank drive (10) from a support tube (25), at least one to an axis of rotation (9 ) of the eccentric shaft (8) eccentric, separate from the support tube (25) formed Hubzapfen (19) and at least one separate from the support tube (25) formed transmission element (24) is built.

6. The method according to claim 5, characterized in that the crank pin (19) and the gear element (24) applied to the support tube (25) and then by friction welding, hydroforming or shrinking attached thereto.