DE2126059A1 - Crankshaft with connecting rod bearings for reciprocating engines - Google Patents

Description

DORNIER SYSTEM GMBH

Reg. S 122

Crankshaft «with connecting rod bearings for reciprocating piston engines

The invention is concerned with producing a crankshaft for reciprocating pistons. Conventional crankshafts are different depending on the number the cylinder or piston and the piston stroke are correspondingly cranked and have connecting rod journals at their cranked points for mounting the connecting rod carrying the piston. As a result, they all have an essential problem in common, namely their joint problem Generation with a large number of successive operations. In addition, the required accuracy prepares the crankshaft manufacture were operating difficulties. That The greatest problem is the production of bearing journals, namely in particular the main bearing journals. Under no circumstances should these be eccentric with respect to the ideal center line of the flange shaft be. Have the main journals eccentric to one another Deviations, it is not possible for this crankshaft in a very fine system of selection of fit exactly centrally in a crankshaft housing. This major difficulty In the case of the kink waves, the production equation means very high Expenditures for the processing machines and also brings with it the disadvantage of a relatively large amount of rejects. This makes the production of the flute shaft very expensive.

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Another difficulty in making crankshafts lies with the connecting rod bearings. Since their diameter is usually smaller than the diameter of the main bearings, they become large damaged or destroyed earlier. For this reason, their diameters have already been made the same as those of the main bearings. Even this training has not yet led to a satisfactory result. Another disadvantage of the connecting rod journals is that they usually have different stroke sizes and also still have an angular offset from one another. However, unequal stroke and angular misalignment mean a significant deterioration in operation the squeeze head system most commonly used in combustion engines today. Sine mass production of extreme small squeeze head gaps becomes impossible for these reasons.

Another serious disadvantage is that in the crankshaft from cylinder to cylinder is an interrupted power flow. Also the torsional stiffness of the crankshaft leaves a lot to be desired, as usually due to the engine torque Twists in the crankshaft at least a few degrees occur. This also causes an angular offset of the Caused connecting rod journals and the above disadvantages are exacerbated.

In addition, there are vibration problems because of torsional vibrations the crankshaft cannot be controlled or only insufficiently. Another disadvantage is the poor lubrication

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Mention should be made of the proportions of the main and connecting rod bearings. The lubricant transport must namely take place against the centrifugal force inside the cranked crankshaft.

A special type of crankshaft design is known from the so-called disc crankshaft. This form of training does not show any crookedness, rather are with her the diameter of the main bearings expanded beyond the crank radius and formed into disks. The connecting rod pins are between two adjacent discs used. In this way, large main bearing diameters are obtained and roller bearings can be used there and insert the entire crankshaft from the side into the machine housing. But all remain Rs The above-mentioned disadvantages of the known crankshaft also exist in this disc crankshaft. Darttber brings the Disc crankshaft a very considerable increase in the cost of manufacture with it.

The invention was based on the stated disadvantages to avoid and to create a new shape of a crankshaft, which allows a very precise, but nevertheless simple manufacture, thus brings little scrap and is therefore cheap to manufacture. The main aim of this new crankshaft is to have an exact centric one Allow arrangement of the main bearing journals, if possible be torsionally stiff and thus avoid torsional vibrations. In addition, the training should offer very good lubrication options,

so that the connecting rod bearings are damaged even if they are overstrained is no longer possible. The goal is achieved according to the invention by designing the crankshaft as a continuous, straight one and a shaft mounted in the motor housing with eccentric disks fixed thereon as a carrier for the connecting rod bearings, wherein according to a first balancing condition, the mass of each piston around the associated piston pin, according to a second balancing condition the sum of the masses of piston and piston pin and connecting rod bearing with connecting rod with an assigned counterweight around the center of the eccentric and, according to a third balancing condition, the total mass of the two preceding conditions balanced masses including the eccentric disk and a further counter mass around the axis of the continuous Shaft are statically and dynamically balanced.

According to a further embodiment of the invention, the through shaft can advantageously be designed as a hollow shaft. In addition, a known damping element, e.g. a soft iron tube, can be provided inside the hollow shaft in order to be able to completely control any interfering torsional vibrations that may occur.

Regardless of whether a tubular shaft or solid shaft is used, such a design of the crankshaft offers as an eccentric shaft, the greatest accuracy for the manufacture of the main bearing journals and their exact centric arrangement when stored in the motor housing. The connecting rod journals can also be manufactured with the greatest possible precision. Which he-

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crankshaft according to the invention is also very easy to manufacture, because on a continuous piece of shaft that - how mentioned - a hollow or solid shaft, the individual eccentrics are pushed on and at their correct angle » position so that the bearing parts of the main bearings of this crankshaft are exactly centric under all circumstances, since they lie on a continuous shaft. The second big advantage this Kxzenterwellenausbildung is the possible precision of the individual bearing journals. While with the conventional crankshaft the connecting rod journals had to be ground exactly one has to do with the eccentric shaft according to the invention with circular disks of the same size, which one with the other with a very small manufacturing tolerance and are only drilled eccentrically. This eccentric drilling is from the center the eccentric disk with a very small tolerance in terms of production Favorably arranged and serves as a receptacle for the continuous basic shaft of the eccentric shaft, so that both the main bearing journals as well as the connecting rod journals are manufactured with a very high level of production accuracy using inexpensive means can be. This practically avoids rejects. The manufacturing costs for an eccentric shaft are at most At a fifth to a quarter of the price that would have to be paid for a conventional crankshaft, that too is still fraught with all of the above inaccuracies.

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In addition, eccentric wheels offer the great advantage that they have a continuous flow of force and are torsionally stiff. Since a very extensive uplift is possible, torsional vibrations are reduced to a fraction of the previously occurring torsional vibrations. With the balancing conditions you can possibly get by with a very simple arrangement in boxer engines with 4 or more cylinders, because there the counterweight required by the third balancing condition can be replaced by the paired arrangement of the opposing pistons. Another advantage of the eccentric shaft is that the connecting rod bearings themselves can be designed to be undivided. It is therefore possible to push them onto the associated eccentric disks from the side. The lubrication ratios are also significantly improved, since the lubricant can be supplied axially through the central shaft and from there by its own centrifugal force via continuous radial bores through the eccentric disk to the piston pin bore the connecting rod can be guided. In terms of force, the eccentric shaft has the advantage that the explosive force of the Gases and thus the gas pressure from the piston via the piston pin and the connecting rod are no longer limited to a specifically narrow one, i.e. with a small diameter bearing is transferred, but to an eccentric disk with a large diameter, whereby the oil surface pressure compared to the previously common connecting rod bearings is smaller by the corresponding diameter ratio.

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This results in a significant protection of the connecting rod bearings, the

consequently obtain a considerable increase in their service life.

An exemplary embodiment of the invention is as follows

explained on the basis of the drawings. Show it:

Fig. 1 shows the principle of the eccentric shaft greatly simplified,

Fig. 2 schematically shows the eccentric shaft with the eccentric disk in axial view,

3 shows the side view of FIG. 2,

4 schematically shows the position of the eccentric disks and pistons with a four-cylinder in-line engine,

Fig. 5a schematically shows the position of the eccentric disks and pistons in a four-cylinder boxer engine in an axial direction View, .

FIG. 5b shows the side view of FIG. 5a,

6a schematically shows the position of the individual eccentric disks in a four-cylinder in-line engine with a 45 ° V position,

FIG. 6b shows the superimposition of the individual representation from FIG. 6a in FIG axial view,

FIG. 6c shows the side view of FIG. 6b 7a schematically shows the position of the individual eccentric disks

for a four-cylinder in-line engine with 30 ° V position,

FIG. 7b shows the superimposition of the individual representation from FIG. 7a, FIG. 7c shows the side view of FIG. 7b.

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In Fig. 1 is the central, continuous shaft with 1 designated. The axis of the shaft bears the reference symbol D. The cylinder axis is perpendicular to the continuous shaft 1 in dash-dotted lines Z indicated. An eccentric disk 2 is attached to the continuous shaft 1. This eccentric disc carries that Connecting rod bearing 3. From the connecting rod bearing, the connecting rod 4 leads to

| Piston pin 5, which carries the piston β. The continuous, central one Shaft 1 and its bearing in the motor housing will be described later.

In order to meet the avoidance conditions, you must first the piston 6 must be balanced around the piston pin 5. Of the The center of gravity Sg is in the piston pin 5. Then the in the center of gravity S_ combines the imaginary mass of piston and piston pin balanced together with the masses of the connecting rod bearing 3 and connecting rod 4 around the center S_ with a counter mass 7. In the center of gravity G of the counterweight 7 is the same

"Mass arranged like the sum of the masses of piston, piston pin, connecting rod bearing and connecting rod. In the middle of the eccentric disk 2, the total mass of piston; connecting rod, connecting rod bearing, counter mass 7 and eccentric disk 2 can be thought of as being combined _{in the center of gravity S x} In the eccentric center of gravity 8 _χ , the system that is imagined and balanced according to the first two balancing conditions is on your part about the axis D of the continuous shaft according to the third balancing condition

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to balance statically and dynamically · For this purpose, a counterweight _{8 corresponding to Ilasse S x} with a center of gravity S is arranged. The three interacting balancing conditions result in a perfectly balanced overall system that no longer exhibits any oezilizing movements.

Figures 2 and 3 show a simplified design Embodiment of the eccentric shaft. Ss are for same Parts have the same reference numerals as in FIG. 1. It is easy to see the continuous main shaft 1, which is in the Bearings 9 is stored in the motor housing. On both sides of the eccentric disk 2, the counterweights are each at a distance a to the total mass S ~ on two equally large counterweights 8 with Focus S .. arranged divided. The two groden the same Partial masses 8 sit · * firmly on the continuous shaft 1. After the third balancing condition must focus on S "and S" both have the same distance r from the axis D of the through shaft 1.

In the through shaft 1, which is shown here as a hollow shaft, there is also a soft iron tube 13 as a damping element arranged. The required lubricant is introduced into the continuous shaft x 1 in the axial direction. Got from there it through radial bores 10 'through the wall of the shaft 1 through into a channel 10 which passes through the eccentric 2

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passes through. This Schniermittelkana1 10 opens into a groove in the connecting rod bearing 3. From there the bearing gap 3 * of the connecting rod bearing is lubricated. Furthermore, one leads from the groove 11 Hole 12 through the connecting rod 4 to the piston pin hole 5 * of the connecting rod. The oil is only transported in the direction of centrifugal force and no longer opposed to it. As a result, lubrication is much easier and improved.

As the drawing also shows, one can undivided Use connecting rod bearing 3 'and the entire connecting rod bearing from Slide the side onto the eccentric 2. This makes the assembly of the eccentric shaft and the connecting rod with the piston essential simplified.

In FIG. 4, the four cylinders I-IV of a four-cylinder in-line engine are drawn out side by side. The continuous shaft is again indicated by 1, as is the respective cylinder axis Z with dash-dotted lines. The eccentric disk 2 and its center of gravity S _x and the counterweight 8 with its center of gravity Sj. are shown; likewise the connecting rod 4. The four positions of the four pistons I - IV show that a perfect balancing of the entire system is possible. The individual pistons are each drawn in a position of approximately 45 ° with respect to their TDC or BDC position. Each piston and each eccentric disk is individually balanced according to the balancing conditions described above. Thus, each piston is also assigned its own counterpart 81.

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2126053

The simplified relationships for a four-cylinder boxer engine are shown in FIGS. 5a and 5b. Included two cylinder pairs are drawn out side by side. Here too, the eccentric shafts or pistons are at 45 ° compared to OT-Özw. UT position shown offset. The side view of Fig. 5b clearly shows the continuous main shaft 1 as well as the eccentric disks 2 arranged on it. The continuous shaft is stored in the main bearings 9a, 9b, 9c. As mentioned above, in this way an exact centering of the main shaft bearings is achieved. Due to the boxer arrangement the piston is In this special embodiment, no counterweight 8 is required on the individual pistons, but rather serve to balance the masses the two pistons assigned to one another. The same simplified design is of course also available for a six-cylinder or eight-cylinder boxer engine possible, or with in-line engines with more than eight cylinders. An application of the However, complete balancing conditions according to FIG. 1 may not be ruled out even in the case of boxer engines.

Figures 6a to 6c show a four-cylinder in-line engine, whose four cylinders I - IV are in a 45 ° V position. Here are the individual pistons in their TDC or. UT position shown. The balancing takes place here according to the example in Fig. with a separate counterweight 8 for each piston or with two divided partial weights 8.

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In FIGS. 7a to 7c there is again a four-cylinder in-line engine marked with a 30 ° V position. With this one The pistons are about 15 ° compared to the selected representation OT or UT position offset. Again, every single piston is there or each individual eccentric disk is assigned a counterweight 8, whereby the counter mass is again divided into two parts.

. The through shaft 1 old the main bearings 9a, 9b, 9c is closed recognize.

The inventive eccentric shaft has compared to the previous crankshafts not only have the advantage of greater accuracy and better balancing options, but also before all things have the advantage that no transfer lines and complicated processing machines are required for their generation process are, but a few machine tools are sufficient, whereby the end result is a generation accuracy, as was previously possible with crankshafts only with a great deal of effort.

w was borrowed. The eccentric shaft proposed here represents a significant advance in terms of production and functionality compared to the previous crankshaft.

2 Mar 9, 1971
KTlO / construction / mo.

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Claims (1)

Reg. S 122 Claims Crankshaft with connecting rod bearings for reciprocating piston engines, marked due to their design as a continuous, straight shaft (1) mounted in the motor housing, with a fixed shaft Eccentric disks (2) as carriers of the connecting rod bearings (3), wherein, according to a first balancing condition, the mass of a Each piston (6) around the associated piston pin (5), according to a second balancing condition, the sum of the masses of piston (6), piston pin (5) and connecting rod bearing (3) with connecting rod (4) with an assigned counterweight (7) around the eccentric see ibenmit te (S _3. ) and according to a third unbalance condition, the total mass of those balanced according to the two above conditions Masses (3,4,5,6,7) including the eccentric disc (2) and a further counterweight (8) are statically and dynamically balanced around the axis (D) of the through shaft (1). 2. Crankshaft according to claim 1, characterized by training the through shaft (1) as a tubular hollow shaft. 209851/0196 3. Crankshaft according to claim 2, characterized by an im Known damper for torsional vibrations (e.g. soft iron tube 13) arranged inside the hollow shaft (1). 4. Crankshaft according to one of claims 1 to 3, characterized in that that the counter mass (8) of the third balancing condition from two equidistant (a) in front of and behind the eccentric disk (2) arranged equal partial masses is composed. 5. Crankshaft according to one of claims 1 to 3 for boxer engines with four or more cylinders, characterized in that in the third balancing condition the counterweight (8) by the Pairs of opposed pistons (I, II and Ill, IV in Flg. 5) ersetzfaoüi let. β. Crankshaft according to one of Claims 1 to 5, characterized through continuous radial lubricant bores (10 *, 10,12) from the full one (1) through the cam disk (2) to the piston pin bore (5 *) of the connecting rod (4). 7. Crankshaft according to claim β, characterized by one of the Radial bore (12) in the connecting rod (4) outgoing and extending at least over part of the connecting rod bearing (3) Groove (11). 209851 / 019G - 3 - 8. Crankshaft according to one of claims 1 to 7, characterized through undivided connecting rod bearings. March 29, 1971
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