The invention relates to an internal combustion engine according to the preamble of claim 1.
These internal combustion engines have an eccentric shaft, also referred to as an adjusting shaft, which is driven by the crankshaft via a spur gear at half the rotational speed of the crankshaft and with a direction of rotation opposite to the direction of rotation of the crankshaft and at the same time is coupled to the crankshaft via a crank drive, which couples the coupling links and also referred to as Anlenkpleuel connecting rod and because of the articulation of the coupling members to the crankshaft, the articulation of the connecting rod to the eccentric shaft and the articulated connection between each coupling member and the adjacent connecting rod is hereinafter also referred to as multi-joint crank mechanism.
By this arrangement, in four-stroke internal combustion engines, the expansion and exhaust stroke, d. H. the piston stroke at the expansion and exhaust stroke, compared to the intake and compression stroke, d. H. the piston stroke during the intake and compression stroke to be increased. However, in the case of inline four-cylinder internal combustion engines, a free torque of 0.5th order which otherwise does not occur in such series internal combustion engines is caused by the multi-joint crank drive, whereby the smooth running or running culture is considerably impaired in the internal combustion engines of the type mentioned at the outset.
Proceeding from this, the present invention seeks to improve an internal combustion engine of the type mentioned in that this free moment 0.5.-order can at least be reduced or eliminated altogether.
This object is achieved with an internal combustion engine having the features of claim 1.
By attaching preferably two or more balance weights to the eccentric shaft, at least the dominant portion of the free moment 0.5th order of the opposite direction of rotation of the crankshaft rotational direction can be fully compensated. Next arise by this measure only minimal additional costs and a minimum extra weight, but no additional friction losses.
The balancing weight according to the invention or the balancing weights according to the invention are used exclusively for the reduction or elimination of the free moment 0.5th order. On the other hand, they do not serve to compensate the rotating masses of the Anlenkpleuel and are not suitable because of the different speed of the eccentric shaft and the crankshaft to compensate for the rotating masses of the connecting rod between the piston and the crankshaft and the coupling links.
A preferred embodiment of the invention provides that the counterweights are arranged in the vicinity of the two opposite ends of the eccentric shaft, preferably between the respective front end and adjacent to the front end, to the axis of rotation of the eccentric shaft eccentric shaft journal, to which the Anlenkpleuel of the 1st Cylinder or the 4th cylinder is attached.
According to an advantageous embodiment of the invention, the two balancing weights have an identical shape, preferably in the form of an angular segment, and an identical mass whose center of gravity is advantageously offset from one another by 180 degrees with respect to each other.
It has been found that a particularly good balance of the 0.5. Order free moment can be achieved if an angular offset between the center of gravity of the counterweights and a plane spanned by the axis of rotation of the eccentric shaft and a longitudinal center axis of the adjacent journal is between 25 and 40 degrees and preferably about 32 degrees.
In the following the invention will be explained in more detail with reference to an embodiment shown in the drawing. Show it
1 a perspective view of cooperating parts of an internal combustion engine with extended expansion stroke;
2 a perspective view of an eccentric shaft with drive wheel and balance weights 1 ;
3 an end view of the eccentric shaft in the direction of the arrows III-III in 2 ;
4 another perspective view of the eccentric shaft with the balance weights and without drive wheel;
5a and 5b Bar graphs of free moments of different order and direction in the crankshaft of the internal combustion engine before and after the attachment of balance weights on the eccentric shaft.
How best in 1 shown comprises the four-stroke 4-cylinder internal combustion engine only partially shown in the drawing 1 in series with extended Expanisonshub four pistons 2 and a crankshaft 3 , Each of the pistons 2 is in one of the four cylinders (not shown) of the internal combustion engine 1 movable up and down and is by a Kolbenpleuel 4 with the crankshaft 3 connected. The crankshaft 3 is in main storage chairs of a cylinder crankcase (not shown) of the internal combustion engine 1 rotatably mounted and has five serving for storage centric shaft journal 5 and four crank pins 6 (Only one visible), whose longitudinal central axes in different angular orientations parallel to the axis of rotation 7 the crankshaft 3 are offset.
On each of the crank pins 6 the crankshaft 3 is a coupling link 8th around the longitudinal center axis of the crank pin 6 rotatably mounted. At each coupling link 8th is one of the Kolbenpleuel 4 hinged, the lower forked front end 9 with two eyelet-shaped legs. Between the two legs of the forked front end 9 of Kolbenpleuels 4 grips the free end of one over one side of the crankshaft 3 protruding short lifting arm 10 of the two-armed coupling member 8th a, which is provided between the legs with a bearing bush (not visible). Through the eyes of the legs and the bearing bush, a bearing pin extends 11 which is in the bearing bush of the lift arm 10 is rotatably mounted.
In contrast to conventional internal combustion engines, in which the piston stroke has the same length over all cycles, is in the illustrated internal combustion engine 1 the lifting height of the pistons 2 during the expansion and exhaust stroke longer than during the intake and compression stroke. For this purpose, by the rotation of the crankshaft 3 caused movement of Kolbenpleuel 4 an additional component of motion superimposed.
This is done by means of an eccentric shaft 13 one to the axis of rotation 7 the crankshaft 3 parallel axis of rotation 14 has, next to the crankshaft 3 and slightly below this is rotatably mounted in the cylinder crankcase. The eccentric shaft 13 is from the crankshaft 3 via a reduction gear 15 at half the speed of the crankshaft 3 and with one to the direction of rotation of the crankshaft 3 driven in opposite direction of rotation. In addition, the eccentric shaft 13 via a multi-joint crank drive 16 with the crankshaft 3 coupled.
As in 1 illustrated, comprises the reduction gear 15 a first, rotationally fixed on the crankshaft 3 mounted gear 17 and a second rotationally fixed on the eccentric shaft 13 mounted gear 18 meshing with each other. To achieve the desired reduction ratio of 2: 1, the number of teeth of the second gear is 18 twice the number of teeth of the first gear 17 ,
The multi-joint crank drive 16 includes next to the coupling links 8th one of the number of Kolbenpleuel 4 corresponding number of Anlenkpleueln 19 , which are approximately parallel to the piston rods 4 aligned and in the axial direction of the crankshaft 3 and the eccentric shaft 13 each approximately in the same plane as the associated Kolbenpleuel 4 are arranged. The lower end of each Anlenkpleuel 19 is pivotable on a shaft section 20 the eccentric shaft 13 attached, in relation to the axis of rotation 14 the eccentric shaft 13 is eccentric. The upper end of each Anlenkpleuel 19 is above the eccentric shaft 13 on a longer coupling arm 21 of the two-armed coupling member 8th hinged. The coupling arm 21 has a bifurcated front end 22 with two eyes provided with eyes, between which is provided with a bearing bushing upper end of the Anlenkpleuels 19 intervenes. Through the eyes of the legs and the aligned bushing of the Anlenkpleuels 19 extends a bearing pin 23 , on which the bearing bush is rotatably mounted.
The to the individual cylinders of the internal combustion engine 1 associated eccentric shaft sections 20 are in the circumferential direction of the eccentric shaft 13 offset by a split angle against each other to account for the firing order of the cylinder. This ensures that the cylinder in which the fuel / air mixture is just ignited makes the expansion stroke longer.
Apart from the extended expansion stroke can also be the inclination of Kolbenpleuel by the arrangement described above 4 with respect to the cylinder axis of the associated cylinders during rotation of the crankshaft 3 can be reduced, resulting in a reduction of the piston side forces and thus the friction forces between the pistons 2 and cylinder walls of the cylinder leads.
However, the multi-joint crank mechanism causes 16 a free moment M, which can be divided into two parts whose direction is part of the Direction of rotation of the crankshaft 3 and partly the direction of rotation of the eccentric shaft 13 corresponds, as in 5a and 5b shown in bar charts, where the bar shown on the right of each bar pair by the multi-joint crank mechanism 16 caused free moment M R with one of the crankshaft rotation direction 3 corresponding direction and each bar shown on the left of each bar pair, the free moment M L with one of the direction of rotation of the eccentric shaft 13 corresponding, to the direction of rotation of the crankshaft 3 indicates opposite direction over the respective order of the moment.
As it turned out 5a can be seen, especially a large free moment M L 0.5.-order with a to the direction of rotation of the crankshaft 3 generated opposite direction. This free moment M 0.5 L -order leads without countermeasures to a significant impairment of the smoothness of the internal combustion engine 1 while the 1.5-order, 2.5-order, 3.5-order, and 4.5-order free moments are acoustically less critical because of their higher frequencies and smaller amplitudes.
To avoid such an impairment, as countermeasure are two balancing weights 24 . 25 on the eccentric shaft 13 appropriate, as best in 1 to 4 shown. How best in 1 shown, is the first balance weight 24 near a front end opposite to the drive side 26 the eccentric shaft 13 between a serving for supporting the eccentric shaft end face journal 27 and to the front end 26 adjacent first eccentric shaft section 20 arranged, whose position in the axial direction of the crankshaft 3 and the eccentric shaft 13 that of the 1st cylinder in the row of four cylinders of the internal combustion engine 1 equivalent. The second balance weight 25 is near the drive-side front end 28 the eccentric shaft 13 between the gear 18 and to the gear 18 adjacent last eccentric shaft section 20 arranged, whose position in the axial direction of the crankshaft 3 and the eccentric shaft 13 that of the 4th cylinder of the internal combustion engine 1 equivalent.
The two balance weights 24 . 25 both have the shape of an angular segment extending about an angle of about 100 degrees about the eccentric shaft 13 extends around. The two angle segments each have the same dimensions and the same mass. How best in 3 are shown, the two angle segments or balance weights 24 . 25 with a diametrically opposed alignment on the eccentric shaft 13 arranged so that their centers of gravity S 24 , S 25 are offset in the circumferential direction of the eccentric shaft by 180 degrees from each other. The arrangement is chosen such that the center of gravity S 24 of the angle segment of the first balance weight 24 in the circumferential direction of the eccentric shaft 13 an angular distance of 32 degrees to a plane E, that of the axis of rotation 14 the eccentric shaft 13 and the longitudinal center axis of the balance weight 24 adjacent first eccentric shaft section 20 is spanned, and that the center of mass S 25 of the angular segment of the second balance weight 25 in the circumferential direction of the eccentric shaft 13 has an angular distance of 32 degrees to the plane E, through which also the longitudinal center axis of the gear to 18 or to the balance weight 25 adjacent last eccentric shaft section 20 (in 3 not visible), since the longitudinal center axes of the first and last eccentric shaft sections 20 in the circumferential direction of the eccentric shaft 13 180 degrees offset from each other.
By attaching the two balance weights 24 . 25 at the half crankshaft speed rotating eccentric shaft 13 is in operation of the internal combustion engine 1 in the crankshaft 3 a torque M A 0,5.-th order generated that as the moment M R 0,5.-order one of the direction of rotation of the crankshaft 3 has corresponding direction and therefore by the multi-joint crank mechanism 16 counteracts caused moment M L 0.5th order. By a suitable dimensioning of the angle segments of the balance weights 24 . 25 For example, the moment M A of the 0.5th order can be set to be in the opposite direction of the crankshaft 3 rotating proportion of the free moment M L 0.5.-th order, by the multi-joint crank mechanism 16 is caused, completely compensates, as in 5b shown.
LIST OF REFERENCE NUMBERS
- Internal combustion engine
- Shaft crankshaft
- Crankpin crankshaft
- Rotary axis crankshaft
- coupling member
- bifurcated front end piston connecting rod
- Lifting arm coupling link
- bearing bolt
- eccentric shaft
- Rotary axis eccentric shaft
- Reduction gear
- Multi-joint crank drive
- Gear crankshaft
- Gear eccentric shaft
- articulation connecting rod
- eccentric shaft journal eccentric shaft
- Coupling arm coupling link
- bifurcated front end coupling arm
- bearing bolt
- Biting eccentric shaft
- end-face shaft journal eccentric shaft
- Biting eccentric shaft