Multi-joint crank drive of an internal combustion engine, and corresponding internal combustion engine

Abstract

A multi-joint crank drive of an internal combustion engine includes at least one coupling member rotataby supported on a crankpin of a crankshaft for rotation about a coupling member rotation axis; and at least one connecting rod supported on a crankpin of an eccentric shaft for rotation about an eccentric rotation axis, wherein the coupling member is connected with a piston rod of a piston of the internal combustion engine for pivoting about a piston rod rotation axis and with the connecting rod for rotation about a connecting rod rotation axis, said coupling member having a bearing eye receiving the crankpin of the crankshaft, wherein a coupling angle between an imagined straight line though the coupling member rotation axis and the connecting rod rotation axis and an imagined straight line through the coupling member ration axis and the piston rod rotation axis is at least 140 and at most 180, wherein a center point of the coupling member is arranged outside the bearing eye, and on a side of a first plane which faces the piston of the internal combustion engine, said first plane receiving the coupling member rotation axis and the connecting rod rotation axis.

Claims

1. A multi-joint crank drive of an internal combustion engine comprising: at least one coupling member rotatably supported on a crankpin of a crankshaft for rotation about a coupling member rotation axis; at least one connecting rod supported on a crankpin of an eccentric shaft for rotation about an eccentric rotation axis, wherein the coupling member is connected with a piston rod of a piston of the internal combustion engine for pivoting about a piston rod rotation axis and with the connecting rod for rotation about a connecting rod rotation axis, said coupling member having a bearing eye receiving the crankpin of the crankshaft, wherein a coupling angle between an imagined straight line though the coupling member rotation axis and the connecting rod rotation axis and an imagined straight line through the coupling member rotation axis and the piston rod rotation axis is at least 140 and at most 180, wherein a center point of the coupling member is arranged outside the bearing eye, and on a side of a first plane which faces the piston of the internal combustion engine, said first plane receiving the coupling member rotation axis and the connecting rod rotation axis, and an additional mass fastened on the coupling member predominantly on the side of the first plane which faces the piston, wherein a ratio between a distance of the center point to the coupling member rotation axis and a radius of the bearing eye is between 100% and 200%.

2. The multi-joint crank drive of claim 1, wherein the center point is arranged on a same side of a second plane as the connecting rod rotation axis, said second plane being perpendicular to the first plane and receiving the coupling member rotation axis.

3. The multi-joint crank drive of claim 1, wherein the additional mass is made of a material with a greater density than the coupling member.

4. The multi-joint crank drive of claim 1, wherein the additional mass is fastened on a cantilever of the coupling member and/or traverses the cantilever.

5. The multi-joint crank drive of claim 1, wherein the bearing eye is formed by a base body of the coupling member and a bearing cover, said bearing cover being made of a material with a lower density than the base body.

6. The multi-joint crank drive of claim 5, wherein the bearing cover is predominantly arranged on a side of the first plane which faces away from the piston.

7. An internal combustion engine, comprising: a multi-joint crank drive, said multi-joint crank drive comprising at least one coupling member rotatably supported on a crankpin of a crankshaft for rotation about a coupling member rotation axis; at least one connecting rod supported on a crankpin of an eccentric shaft for rotation about an eccentric rotation axis, wherein the coupling member is connected with a piston rod of a piston of the internal combustion engine for pivoting about a piston rod rotation axis and with the connecting rod for rotation about a connecting rod rotation axis, said coupling member having a bearing eye receiving the crankpin of the crankshaft, wherein a coupling angle between an imagined straight line though the coupling member rotation axis and the connecting rod rotation axis and an imagined straight line through the coupling member ration axis and the piston rod rotation axis is at least 140 and at most 180, wherein a center point of the coupling member is arranged outside the bearing eye, and on a side of a first plane which faces the piston of the internal combustion engine, said first plane receiving the coupling member rotation axis and the connecting rod rotation axis, and an additional mass fastened on the coupling member predominantly on the side of the first plane which faces the piston, wherein a ratio between a distance of the center point to the coupling member rotation axis and a radius of the bearing eye is between 100% and 200%.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the following the invention is explained in more detail by way of the exemplary embodiments shown in the drawing without limiting the invention. It is shown in:

(2) FIG. 1 a schematic representation of an internal combustion engine with a multi-joint crank drive,

(3) FIG. 2 a first embodiment of a coupling member of the multi-joint crank drive in a side view,

(4) FIG. 3 the first embodiment of the coupling member in an alternative view,

(5) FIG. 4 a second embodiment of the coupling member,

(6) FIG. 5 a third embodiment of the coupling member, and

(7) FIG. 6 a fourth embodiment of the coupling member

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(8) FIG. 1 shows a region of an internal combustion engine 1 with a multi-joint crank drive 2. The internal combustion engine 1 also has at least one piston 4, which is movable in a cylinder 3 in longitudinal direction. The cylinder 3 or the piston 4 has a longitudinal center axis 5. On the piston 4 a piston rod 6 engages, which is supported on the piston 4 for rotation about a piston rotation axis 7. The piston rotation axis 7 is hereby preferably located on the longitudinal center axis 5 of the cylinder.

(9) On its side that faces away from the piston 4, the piston rod 6 is connected with a coupling member 8. Hereby the piston rod 6 is supported on the coupling member 8 for rotation about a piston rod rotation axis 9. In particular the piston rod 6 engages on a first arm 10 of the coupling member 8. The coupling member 8 is rigidly connected with a second arm 11 so as to form an angle with the second arm. The angle is hereby defined about a coupling member rotation axis 12. In this coupling member rotation axis 12 thus the two arms 10 and 11 converge. The coupling member 8 is supported on a crankpin 13 of a crankshaft 14 for rotation about a coupling member rotation axis 12. The crankpin 13 or the coupling member rotation axis 12 is hereby arranged eccentric relative to a rotation axis 15 of the crankshaft 14.

(10) On the side of the coupling member 8, which faces away from the piston rod 6 a connecting rod 16 engages on the coupling member 8, in particular thus n the second arm 11. Hereby the connecting rod 16 is supported on the coupling member 8 for rotation about a connecting rod rotation axis. On the side of the connecting rod 16, which faces away from the coupling member, the connecting rod 16 is supported on a crankpin 19 of an eccentric shaft 20 for rotation about an eccentric shaft rotation axis 18. The crankpin 19 or the eccentric shaft rotation axis 18 are situated eccentric relative to the rotation axis 21 of the eccentric shaft 20.

(11) It is provided that the rotation axis 21 of the eccentric shaft 20 is arranged above a plane 22, which receives the rotation axis 15 of the crankshaft 15 and is perpendicular to the cylinder longitudinal center axis 5. This arrangement is referred to as above arranged eccentric shaft.

(12) In the Figure a distance between the piston rotation axis 7 and the piston rod rotation axis 9 is designated l.sub.2. The distance between the piston rod rotation axis 9 and the coupling member rotation axis 12 is stated as l.sub.2. The distance between the coupling member rotation axis 12 and the connecting rod rotation axis 17 is designated l.sub.3 and the distance between the connecting rod rotation axis 17 and the eccentric rotation axis 18 as l.sub.4. Particularly preferably the following relationship applies to these distances:
1.41l.sub.11.61,
and/or
0.38l.sub.20.58,
and/or
0.82l.sub.31.02,
and/or
1.63.sub.41.83.

(13) The stated values are hereby in relation to a total piston lift of the piston 4, which is for example at least 70 mm and at most 120 mm.

(14) It can also be provided that a horizontal distance dx between the rotation axis 21 of the eccentric shaft 20 and the rotation axis 15 of the crankshaft 14 in relation to the total piston lift of the piston 4 is at least 0.64 and at most 0.84. In addition or as an alternative the vertical distance d.sub.y between the rotation axis 21 of the eccentric shaft 20 and the rotation axis 15 of the crankshaft 14 is at least 1.64 and at most 2.07 again in relation to the total piston lift.

(15) It can also be provided that in relation to the total piston lift the crank radius of the crankshaft 14, i.e. the distance between the coupling member rotation axis 12 and the rotation axis 15 of the crankshaft 14 is at least 0.23 and at most 0.43. This crank radius is here designated r.sub.1. Also the eccentric shaft 20 has a lift, which is referred to as r.sub.2 and is defined as the distance between the eccentric rotation axis 18 and the rotation axis 21 of the eccentric shaft 20. The crank radius r.sub.2 of the eccentric shaft 20 isin relation to the total piston liftfor example at least 0.045 and at most 0.065.

(16) In addition in the here described multi-joint crank drive 2 a offset s can be provided which is insofar defined as the distance between the rotation axis 15 of the crankshaft 14 and the cylinder longitudinal center axis 5. The offset s, in relation to the total piston lift, is for example at least 0.11 and at most 0.31. Hereby the offset s is present on the side toward the counter pressure side. The rotation axis 15 of the crankshaft 14 is thus arranged on the side of the longitudinal center axis 5 on which also the rotation axis 21 of the eccentric shaft 20 is located.

(17) The coupling angle alpha mentioned above is define by the sectional angle between the imagined straight line, which extends through the coupling member rotation axis 12 and the connecting rod axis 17, with an imagined straight line, which extends through the coupling member axis 12 and the piston rod rotation axis 9. The coupling angle is at least 140 degrees and at most 180 degrees, however it can of course be selected as desired.

(18) The here shown internal combustion engine 1 of course has preferably multiple cylinders 3 and thus multiple pistons 3. Correspondingly the multi-joint crank drive 2 has multiple elements assigned to it, in particular for each piston 4 a piston rod 6, a coupling member 8 and a connecting rod 16. These mentioned elements are respectively configured according to the above description. Generally the number of the cylinders 3 of the pistons 4 of the internal combustion engine 1 can be selected arbitrarily. This number is in particular 2, 3, 4, 5, 6, 8 or 12. When the internal combustion engine 1 is configured with four cylinders the crank angle of the crankshaft 14 is preferably 180 degrees.

(19) FIG. 2 shows a side view of the coupling member 8 in a first embodiment. It can be seen that the coupling member 8 has a bearing eye 23, which after mounting of the internal combustion engine 1 receives the crankpin 13 of the crankshaft 14. A first plane 24 is defined by the coupling member rotation axis 12 and the connecting rod rotation axis 17. Hereby the plane 24 is arranged so that it receives these two rotation axes 12 and 17. A second plane 25 is perpendicular to this first plane 24 and is arranged so that it also receives the coupling member rotation axis 12. The two panes 24 and 25 thus define four quadrants I, II, II and IV which are also indicated.

(20) The coupling member 8 is configured so that a center point 26 of the coupling member 8 is arranged outside of the bearing eye 23. This means that for example the ratio between the distance a of the center point 26 from the coupling member rotation axis 12 to the radius r of the bearing eye 23 is more than 100%, at least 110%, at least 120%, at least 130%, at least 140% or at least 150%. The desired arrangement oft center point 26 in the case of the first embodiment is realized by the arrangement of an additional mass 27 on the coupling member 8.

(21) FIG. 3 shows a further view of the first embodiment of the coupling member 8. Hereby the additional mass 27 can be clearly seen, which is for example form fittingly connected with the coupling member 8. In addition or as an alternative of course a materially bonding connection can be established.

(22) FIG. 4 shows a second embodiment of the coupling member 8. Generally reference is made to the description above. In contrast to the first embodiment the second embodiment has a cantilever 28, which extends into the quadrant I and is hereby oriented away from the coupling member rotation axis 12. The additional mass 27 is fastened on the cantilever 28, in particular form fittingly. For this purpose the additional mass for example extends through the cantilever 28. Preferably the additional mass 27 is configured circular cylindrical. In the exemplary embodiment a longitudinal center axis of the additional mass 27 is preferably arranged parallel to the coupling member rotation axis 12.

(23) FIG. 5 shows a third embodiment of the coupling member 8. Reference is again made to the description above. In the third embodiment the coupling member 8 has a base body 29 and a bearing cover 30. The base body 29 and the bearing cover 30 together form the bearing eye 23 or engage around the bearing eye. The bearing cover 30 is for example fastened on the base body for example with at least one screw connection 31, preferably with at least two screw connections 31. It can be seen that the bearing cover 30 is predominantly arranged in the quadrants III and IV. The bearing cover 30 is made of a material, which has a lower density than the material of the base body 29. Correspondingly the center point 26 (here not shown) of the coupling member rotation axis 12 can be shifted into the quadrant I.

(24) FIG. 6 shows a fourth embodiment of the coupling member 8. Also in this case reference is made to the description above. A contour 32 here indicates the outer contour of the coupling member 8 according to the first embodiment without the additional mass 27. In order to achieve the desired arrangement of the center point 26 also without this additional mass 27 a contour 33 of the coupling member 8 is selected so that the desired center point 26 results from the mass distribution of the coupling member 8.

LIST OF REFERENCE SIGNS

(25) 1 internal combustion engine 2 multi-joint crank drive 3 cylinder 4 piston 5 piston longitudinal center axis 6 piston rod 7 piston rotation axis 8 coupling member 9 piston rod 10 rotation axis 11 1. Arm 12 2. Arm 13 coupling member rotation axis 14 crankpin 15 crankshaft 16 rotation axis 17 connecting rod 18 connecting rod 19 rotation axis 20 eccentric rotation axis 21 crankpin 22 eccentric shaft 23 rotation axis 24 plane 25 bearing eye 26 1. Plane 27 2. Plane 28 center point 29 additional mass 30 cantilever 31 base body 32 bearing cover 33 screw connection 34 contour 35 contour