KR19990029562A - Camshaft with Vibration Damper - Google Patents

Abstract

The cam shaft 1 of the internal combustion engine comprises a plurality of cam disks 10, 11 and a drive wheel 9 with tappet rollers for reciprocatingly driving the pistons and valves of the soft pump. The camshaft has a vibration damper comprising one or more cam disks 10, 11 with a tappet roller loaded with a spring located away from the drive wheel 9. These cam discs 10 and 11 have vibration damping portions deviating from the circular course so that the force from the spring loaded tappet roller affects the camshaft 1 with the torque that changes during operation, so that one of the higher order than 16 The above harmonic torsional vibration is attenuated or compensated.

Description

Camshaft with Vibration Damper

The invention relates to a drive wheel which is synchronously driven with a crankshaft of an engine via a chain drive or gear wheels, a plurality of cam disks with attached tappet rollers for driving the valve in reciprocating motion or for driving the pistons of fuel pumps, from the drive wheel. A vibration damper comprising at least one cam disks with spring loaded tappet rollers positioned at a distance, wherein at least one cam disk of the vibration damper is provided from at least one spring loaded tappet roller. A camshaft of a large two-stroke internal combustion engine, having a circumferential surface cooperating with an attached tappet roller and having a vibration damping portion deviating from the circular course so that the force affects the camshaft in which the torque changes.

U. S. Patent No. 5 272 937 discloses a camshaft of an internal combustion engine, where the vibration damper is integrated with the drive wheel of the camshaft and the camshaft and crankshaft resulting from various torque effects on the camshaft. By reducing the dynamic load on the drive line in between, the noise and wear from the gear wheels and chain wheels of the drive line are reduced. The vibration damper has a plurality of cylindrical holes arranged in the longitudinal axis of the drive wheel parallel to the axis of rotation of the drive wheel and symmetrically distributed around the drive wheel. Rounded disks. The oscillating weights can move freely in the holes and are affected by the centrifugal force during its operation to be pressed toward the position closest to the outer circumferential surface of the drive wheel. As the rotational speed is increased, the centrifugal force is also increased so that the oscillating weight can move in their holes at free frequencies directly proportional to the rotational speed. By vibrating the driving wheel at such a frequency, the oscillating weights oscillate in the hole, thereby generating torque that has a direction opposite to the vibration of the driving wheel to reduce the vibration.

U.S. Patent No. 4 848 183 discloses a camshaft damper for damping the torsional vibration of the camshaft, wherein the damper is also integrated into the drive wheel and has a mass in the form of a ring fixed to the drive wheel by an element of elastic material. It consists of. The inertia of the ring and the elasticity of the elastic body combine to form a vibration system so that during operation, the elastic element absorbs the vibration of the drive wheel and the absorbed energy is converted into thermal energy in the elastic body.

U.S. Patent 5 040 500 discloses a camshaft for controlling valves of an internal combustion engine, where the camshaft has a special cam disk, which can be formed on the drive wheel of the camshaft and is spring loaded. The tappet rollers are affected by varying torque synchronously in the opposite direction and in the same magnitude relative to the torque pulses acting on the camshaft in cooperation with the tappet roller. In other words, it is a vibration damper that completely cancels out the entire vibration contents of the torque pulses resulting from the valve control cam disk. The camshaft with three valve control cam disks can have a special cam disk with three cam disks, each of which is associated with one of the valve control cam disks to operate each valve. When the torque pulse affecting the camshaft to be canceled.

It is an object of the present invention to provide a camshaft of the type mentioned at the outset, in which the risk of unintended wear of the cam disk and tappet rollers is significantly eliminated.

1 is a side view of a camshaft.

2 is a perspective view of a portion of the camshaft of FIG. 1;

Figure 3 shows a cam disk including a tappet roller for fuel injector operation, shown in the direction of the camshaft.

4 and 5 are schematic views of a detachable cam disc comprising a tappet roller loaded with spring for vibration damping according to the invention, shown at right angles to the direction of the camshaft, respectively.

6 shows an example of torsional vibration of an undamped camshaft configured with respect to the rotational speed of the engine.

FIG. 7 is an exemplary diagram corresponding to FIG. 6 in which undesirable higher order harmonic vibrations are attenuated in accordance with the present invention.

Explanation of symbols on the main parts of the drawings

1: Camshaft 9: Drive wheel

10,11,21: Cam disk 15: Housing

16,22: tappet roller

In order to achieve the above object, the present invention provides that a part of the vibration damping portion of the at least one cam disk provided in the vibration damper consists of the sum of one or more varying torques of order greater than 16 with respect to the rotational speed of the cam shaft. It is characterized in that it affects the camshaft with varying torque.

Tappet rollers that drive valves or drive pistons of fuel pumps in large two-stroke, crosshead internal combustion engines jump out of contact with the cam disks by jumping under the influence of higher order harmonic vibrations from the cam disks. There is a high risk of hitting the cam disc, which can result in bumps on the cam disc and tappet rollers. So far this has not been considered in the design of camshaft devices, and since tappet rollers are pressed downward with great force against the cam disks, it is completely improved that the tappet rollers can be released from contact with the cam disks. It has been considered impossible. Such bumps in continued operation result in unexpected heavy wear of the cam disk and tappet rollers. Surprisingly, up to sixteenth order vibrations are typically considered in the vibration calculation of the camshaft device of an internal combustion engine, but in particular, it has been found that the operating state becomes irregular due to one or more harmonic vibrations of order higher than 16th order.

Vibration damping portions can be formed in the cam disk to the extent that the vibration damping takes place and which is out of the circular course, particularly for higher order harmonic vibrations, which is undesirable for any given camshaft.

In addition, the advantage of the vibration damper according to the present invention is used for cam disks with tappet rollers loaded with spring load, and the stable operation of the vibration damper is ensured with a simple, robust and perfect structure.

Vibration damped cam disks are mounted to the camshaft at a distance from the drive wheel. In large engines, the drive wheel has too much weight on the camshaft to form a node for camshaft vibration, so that the vibration damping disk is at a distance from the drive wheel, for example at or near the antinode. Vibration damping is achieved by mounting them.

In one embodiment of the invention, the cam disks of the vibration damper are each positioned so that their floors are positioned at each other's rotational angles corresponding to 360 ° divided by torque orders so as to generate respective torques of orders greater than 16. At least one cam disk having a vibration damping portion over at least a portion. In this way, the vibration damping portions can be made by a constant course formed by alternating ridges and valleys one after the other along the circumferential surface of the cam disks, so that the vibration damping cam disks can be manufactured simply and at a relatively low cost. In this embodiment, cam discs that dampen harmonic vibrations of different orders may be phased together to optimize harmonic vibration damping, which can be particularly advantageous for new engine design work.

In another embodiment of the present invention, the cam disks of the vibration damper are a plurality of courses overlapping each other to generate a sum of a plurality of torques of order greater than 16. One cam disk, each of which has floors located at mutual rotation angles corresponding to 360 ° divided by respective torque orders. When attenuating harmonic vibrations of multiple orders, a disk is not required for each order, and there is an advantage that vibrations of multiple orders can be attenuated to the same disk.

In a preferred embodiment, the cam disks of the vibration damper consist of at least one separate cam disk which is used solely to damp one or more orders of harmonic vibrations without acting simultaneously to drive the fuel pump or valves. This greatly simplifies the design of the vibration damping portion in a separate cam disk since conventional cam disks can continue to be designed as standard units. Mutual coordination, which may be on separate cam discs, has no effect on the operating sequence of the fuel pump or valves. Moreover, the separate cam disks have the advantage that they can be arranged in a wider range in close proximity to the antinodes of the camshaft where the most effective damping is obtained when the vibration damping disks are integrated into the first cam disks of the engine. .

Moreover, in this embodiment the vibration damping cam disks with tappet rollers can be of considerably lighter structure than the cam disk with fuel pump or valve driving tappet rollers, for example the torque required to drive the fuel pumps. This is because a relatively small torque is usually required for the damping of more undesirable harmonic vibrations. For example, the operation of the fuel pump requires a torque of up to 70,000 Nm, while the damping of undesired higher order harmonic vibrations requires, for example, 1,000 Nm of torque. Therefore, pressing the tappet rollers against the vibration damping cam disk requires a relatively small spring force, which means that the parts wear more slowly, operate without problems and ensure a long life. Finally, cam discs with tappet rollers are made of inexpensive mechanical parts and have significant material savings by reducing the weight required for the discs.

In some large engines, the drive wheels are placed between both ends of the camshaft for various structural reasons, so that the cam disks of the vibration damper are close to one end of the camshaft or at least one separate cam disk at both ends. Can include them. In large engines, as described above, the arrangement of the drive wheels between the opposite ends of the cam shaft allows antinodes to be formed at both ends of the shaft, thereby effectively placing the vibration damping cam disks as described above.

Conversely, when the drive wheel is disposed at or close to one of both ends of the cam shaft, the cam disks of the vibration damper are at least one separate cam disk disposed at or near the other end of the cam shaft. It may include, wherein the antinode is formed at the other end.

In another embodiment of the invention, the cam disks of the vibration damper include a cam disk for driving fuel pumps, the vibration damping portion of the cam disk being disposed substantially outside of the circumferential surface portions of the cam disk for activating fuel injection. do. In this way the vibration damper can be integrated into the engine's original cam disks, omitting separate cam disks, and the vibration damping portions cannot negatively affect the operating sequence of the fuel pumps. Since the operating portions of the cam disks controlling fuel pumps belonging to the various cylinders of the engine are substantially uniformly distributed over the course of rotation of the camshaft, the vibration damping portions for the undesirable vibration mode may be arranged in the plurality of cam disks. Can thus be provided with vibration damping valleys and floors throughout the entire course of rotation.

In a variant of the invention, the cam disks of the vibration damper comprise a cam disk for driving an exhaust valve, the vibration damping portion of the cam disk being disposed outside a portion of the circumferential surface of the cam disk for continuously opening and closing the valve. .

Cam disks of the vibration damper may comprise cam disks with vibration damping portions adapted to sufficiently compensate for undesirably large vibration modes. This is particularly advantageous when it is necessary to integrate the vibrating cam discs into the initial cam disc of the engine, in which case vibration damping along the entire circumferential surface of the cam disc, taking into account the operating sequence of the fuel pump and valves as described above. Arranging the parts is inappropriate. Thus, sufficient compensation for the undesirable vibration mode can be carried out outside the operating portion of the cam disk, thereby increasing the energy intensity of the undesirable vibration while the tappet rollers pass through the operating portion of the cam disk where no compensation occurs. This can be avoided and thus an appropriate average attenuation with respect to the rotation of the cam disc can be obtained. This allows incorporation of sufficient vibration damping of an undesirable vibration mode into one of the original cham disks of the engine.

It is sufficient to avoid the negative effects caused by undesirable vibrations by partially compensating for harmonic vibrations of undesirable orders, and thus it is not essential to completely eliminate undesirable vibrations as vibration damping is sufficient.

Hereinafter, with reference to the accompanying drawings showing an embodiment of the present invention will be described in detail the present invention.

1 shows a camshaft 1 of a two-stroke diesel engine with ten cylinders. The cam shaft 1 comprises several parts 2, 3, 4, 5, 6, 7, which parts extend from one another and are connected by a rigid coupling 8. The drive wheel 09 of the camshaft is arranged in the part 5 and is driven synchronously with the crankshaft of the engine by a chain drive or gearwheel transmission, not shown. The other parts 2, 3, 4, 6, 7 are associated with two neighboring cylinders of the engine, respectively, for each cylinder the cam disk 10 for fuel pump operation and the cam disk for operation of the exhaust valve. (11) is supported. For the sake of simplicity, all cam disks 10, 11 of FIG. 1 are shown at their maximum diameter. The camshaft 1 shown is for a 10-cylinder engine, the crankshaft being divided into two parts because of its weight, and the transmission between the camshaft 1 and the crankshaft is arranged in this division. In addition, the cam shaft 1 can be manufactured in one part, and there is no problem in the use of the present invention. Moreover, the transmission between the crankshaft and the camshaft 1 is located at the end of the crankshaft.

The drive wheel 9 has a larger diameter than the other parts of the cam shaft 1 and has a greater weight than the rest of the cam shaft 1 to have a greater moment of inertia than the rest of the cam shaft 1. The node for the torsional vibration of the camshaft 1 is formed.

FIG. 2 is a perspective view of one of the intermediate parts 3, 4, 6 of the camshaft shown in FIG. 1 with cam discs 10, 11. On the left half of the camshaft, a first set of cam discs 10, 11 consisting of two spaced discs is joined by heat press-fitting, of which the cam disc 10 on the left side is the first one. The cam disc 11 on the right side acts to actuate the exhaust valve of the cam cylinder. In the right half of the camshaft, a second set of cam disks 10, 11, like the first set, is provided for the second cylinder. Although not shown, the cam shaft 1 is supported in each set of cam disks 10, 11 by sliding bearings provided on two cam disks.

3 shows a cam disk 10 arranged in the roller guide housing 15 and on the cam shaft 1, which is provided with an attached tappet roller 16, which is provided with the tappet roller 16. ) Is built-in adjacent to the cam disk 10 and is connected to a fuel pump (not shown) and rolls on the circumferential surface of the cam disk 10 during operation of the engine. The circumferential surface of the cam disk has an actuating part comprising two different regions 17, 18, the distance from one region to the axis of rotation 19 of the cam shaft is increased and the distance from the other region to the axis of rotation of the cam shaft is reduced. do. One of the zones 17 actuates the fuel pump when the engine is operating in the normal direction of rotation indicated by the arrow 20 and the other zone 18 allows the pump to operate after the direction of rotation is reversed. . When the operating part passes through the tappet roller 16, the tappet roller is pressed upwards to operate the fuel pump. The cam discs 10 associated with the other cylinders are arranged on the camshaft 1 such that the fuel injection actuating parts rotate about the camshaft 1 with respect to each other such that the fuel injection conforms to the ignition sequence of the engine concerned. . The cam disc 11 for the operation of the exhaust valve operates according to known principles.

4 and 5 show a separate cam disk 21 adapted to attenuate torsional vibrations in the camshaft 1. The separate cam disc 21 acts entirely for vibration damping and is not located in the camshaft 1 of the conventional cam discs 10, 11, which must be changed essentially but for example vibrates in close proximity to the antinode. The damping effect is arranged at an appropriate position of the cam shaft 1. The separate separate cam disc 21 may be mounted on a separate camshaft portion, not shown, which camshaft portion is connected to the remaining portion of the camshaft 1 or the cam discs 10, 11 of the camshaft. May be directly heated indented into one of them.

As with conventional cam discs 10 and 11, a separate separate cam disc 21 has an attached tappet roller 22, which tappet roller 22 has a separate cam disc 21 during operation of the engine. ) Is held by the spring 23 and rolling in a separate cam disk 21. The tappet roller 22 is suspended from the slider 24 so that its central axis is parallel to the cam shaft 1, and the slider 24 is cam shaft 1 in the roller guide housing 25. Guide at right angles to The circumferential surface of the separate cam disk 21 is substantially circular, and a plurality of vibration damping portions in the form of the valleys 27 and the floor 26 are formed, and the tappet roller on which the spring acts is a separate cam disk 21. As it rotates it moves along the vibration damping portions of the valleys and floors. The cam disk is eventually affected by torque which varies with the distribution of valleys and ridges along its circumferential surface. Vibration damping The separate cam disc 21 is phased relative to the cam shaft 1 so that a torque that varies with the distribution of the valleys 27 and the floor 26 portions is undesirable in the cam shaft 1. The torque is canceled so that the torque is attenuated or eliminated.

A separate separate cam disk 21 may be undesirably designed to damp large harmonics of higher or higher order. 4 shows an example of the circumferential surface shape of a separate cam disc 21 to attenuate undesired 38th order harmonic vibrations. Along the circumferential surface, 38 uniform vibration damping portions are formed, each of which consists of a valley 27 and a ridge 26, which are arranged at the same rotation angle to each other. The radial distance difference between the valleys 27 and the floor 26 is relatively small compared to the diameter of the separate cam disc 21. For example, the distance difference is the diameter of the separate cam disc 21. In the case of 1m it can be 6mm. During operation of the engine, the tappet roller 22 causes 38 torques to be increased or decreased for each rotation of the cam shaft 1 to affect the separate cam disk 21 to thereby effect the 38th order harmonic torsional vibration of the cam shaft 1. Attenuate

In the case where plural different orders of harmonic vibrations are undesirable, a separate cam disc 21 may be used, which is adapted to attenuate vibrations of that order for each order, or a plurality of such undesirable orders of vibration. A single separate cam disk 21 can be used to damp the. Such a separate cam disk 21 for damping vibrations of a plurality of orders may have a circumferential surface with an unshown wave shape consisting of valleys and floor portions, the wave shape having various wave shapes. And the respective wave shapes are formed on each of the separate cam disks 21 to attenuate harmonic vibrations of each order.

6 and 7 show the effect of the present invention in the example of a 10 cylinder, two-stroke diesel engine of the MLA BW company of the type 10L90MC (where '90' represents a cylinder diameter of 90 cm). have. In the engine, the drive wheel 9 is mounted at the position of the cam shaft 1 shown in FIG. 1. In the table shown, the abscissa represents the rotational speed of the engine in revolutions per minute, and the ordinate represents the torsional vibration of the camshaft 1 of Miliradian per second. Moreover, the vertical line, denoted by MCR, represents the maximum continuous specific speed of the engine. In general, large diesel engines must be able to operate continuously at or below these speeds for most of the operating time and for a long time, so that undesirably large torsional vibrations are not generated in the camshaft 1 in a specific operating range. It is important.

In the table of FIG. 6, the graph shows the accumulated torsional vibration in the camshaft 1 when not using the vibration damping device according to the invention. The graph in the table clearly shows that it has an important floor 28 at 79-84 rpm, which is highly undesirable as it is within the normal operating range. This accumulated torsional vibration can be decomposed into multiple orders of harmonic vibrations of various orders in a manner known by the Fourier analysis method such that the sum of these harmonic vibrations forms the vibration mode represented by graph a. Below graph a, a number of graphs c show the most significant harmonic vibrations, each graph showing a particular order of harmonic vibrations as indicated therein. It is evident that the 38th and 39th order harmonic vibrations contributed to the undesirable floor 28 of graph a.

Graph b in the diagram of FIG. 7 shows the torsional vibrations accumulated in the camshaft 1 when the 38th and 39th harmonic vibrations are attenuated by one or more cam disks according to the invention. Indeed, the graphs for these two harmonic vibrations have been omitted from the diagram, and the fragment b which actually constitutes the sum of the remaining harmonic vibrations does not have the particularly sharp ridge 28 shown in FIG. Thus, undesirable vibration modes were greatly attenuated.

Unfavorable 38th and 39th harmonic vibrations are combined with one or more corresponding cam disks having 39 floors 26 on the circumference to form a circle with 38 floors 26 as shown in FIG. 4. It can be attenuated by one or more separate cam disks 21 having a major surface. In a simple embodiment of the invention, in the camshaft 1 shown in FIG. 1 and adapted to be installed in an engine of the 10L90MC type, a separate cam disk 21 with 38 floors and a separate cam disk with 39 floors 21 may be disposed at one end of the camshaft 1. In another embodiment, the drive wheel 9 may be arranged at one end of the camshaft 1, and a separate separate cam disk 21 may be arranged at the other end of the camshaft.

During the commissioning of such a camshaft 1 prototype, the mutual phase shift between two separate cam discs 21 can be optimized for the best possible attenuation, so that the phase shift can be optimized for practical use. A single cam disk can be made to attenuate the determined 38th and 39th vibrations. In another embodiment of the present invention, a separate cam disk (not shown) is mounted at one or both ends of the cam shaft 1 shown in FIG. 1 to damp the 38th and 39th harmonic vibrations. Different numbers and cam discs may be used at different locations depending on the amplitude and spacing conditions of the undesirable vibration.

Undesirably large harmonic vibrations in the camshaft 1 are in particular the 38th and 39th order, the above-described embodiment being a constant angular position and constant of the first cam disk 10, 11 of the engine relative to the camshaft 1. Applies to the engine of type 10L90MC in ignition order. If the angular position of the cam disks 10, 11 is slightly different or the ignition order is different, the cam shaft 1 of this engine has a completely different vibration mode due to the large contact force between the cam disks 10, 11 and the tappet rollers. Are generated so that the undesirable large harmonic vibrations are of a different order. According to the invention, undesired harmonic vibrations can be attenuated by the cam disk in the manner described above for the damping of these particular orders. Moreover, in other relatively large engine types, such as the 8L60M type of MB & W with eight cylinders having a cylinder diameter of 60 cm, undesirable harmonic vibrations of a different order than those described above can occur.

In order to apply damping to the amplitude of the undesirable vibration, the amplitude of the vibration damping portion of the separate cam disc 21 described above, along with the dimensions and weight of the separate cam disc 21 and the tappet roller 22 Variables such as the full load and spring coefficient of the spring 23 pressing the tappet roller 22 against the separate cam disk 21 must be changed. The phase shift between the torque that causes undesirable vibration and the torque that damps the vibration moves the tappet roller 22 in the direction of the circumferential surface of the cam disks or dampens the vibration with respect to the cam shaft 1 to optimize the damping. Can be adjusted by rotating a separate cam disk 21.

Other embodiments of the vibration damping cam disks described above and their positions in the cam shaft 1 can also be combined. That is, a separate and separate to attenuate undesired harmonic vibrations of one order in combination with portions that attenuate undesired harmonic vibrations of another order disposed on one or more cam disks 10 driving the fuel pump. Cam disc 21 can be used. Also, for example, to attenuate undesirable harmonic vibrations of other orders in proximity to an antinode located between some conventional cam disks 10, 11 and at some distance from the ends 13, 14 of the cam shaft. It is also possible to arrange a separate cam disk 21 at the same time as to arrange a separate cam disk to attenuate one order of undesirable harmonic vibration at the end of the cam shaft.

An advantage of the vibration damper according to the invention is that it is used in cam disks with tappet rollers loaded with spring load, and the stable operation of the vibration damper is ensured by a simple, robust and perfect structure. In addition, according to the present invention, it is also possible to have the cam disks damping different orders of harmonic vibrations phased together to optimize the harmonic vibration damping, which can be of particular advantage for new engine design work. Since conventional cam disks can continue to be designed as standard units, it becomes quite easy to design the vibration damping portion in a separate cam disk, and the mutual adjustment that can be in the separate cam disks is dependent on the operating sequence of the fuel pump or valves. It has no effect. Moreover, the separate cam disks have the advantage that they can be arranged in a wider range in close proximity to the antinodes of the camshaft where the most effective damping is obtained when the vibration damping disks are integrated into the first cam disks of the engine. . In addition, in this embodiment, the vibration damping cam disks with tappet rollers have an advantage that the structure can be considerably lighter than a cam disk with fuel pump or valve driving tappet rollers.

Claims (9)

A plurality of cam disks 10, 11 with a drive wheel 9 synchronously driven with the crankshaft of the engine via chain drive or gearwheels, tappet rollers driving the valves in reciprocating motion or driving the pistons of the fuel pumps And a vibration damper comprising at least one cam disk (10, 11, 21) to which spring loaded tappet rollers (16, 22) are located at a distance from the drive wheel (9). The at least one cam disk 10, 11, 21 of the damper has a circular course such that the force from the tappet rollers 16, 22 under at least one spring load affects the cam shaft 1 where the torque changes. A camshaft of a large two-stroke internal combustion engine having a vibration damping portion deviating from and having a circumferential surface cooperating with the attached tappet rollers 16 and 22, comprising: at least one cam disk provided in the vibration damper ( 10,11,21) A portion of the vibration damping portion is characterized in that it is adapted to affect the cam shaft 1 with a varying torque consisting of a sum of one or more varying torques of order greater than 16 in relation to the rotational speed of the cam shaft 1. Camshaft. 2. The cam disks 10, 11, 21 of the vibration damper are each raised at their respective rotation angles corresponding to 360 ° divided by the torque orders so as to generate respective torques of orders greater than 16. At least one cam disk having a vibration damping portion over at least a portion of the circumferential surface to be positioned. 3. The cam disk (10, 11, 21) of the vibration damper according to claim 1 or 2, wherein the cam disks (10, 11, 21) of the vibration damper are formed of a plurality of courses overlapping to generate a sum of a plurality of torques higher than 16. At least one cam disk having at least a portion formed with valleys and floors, each course comprising floors located at mutual rotational angles corresponding to 360 ° divided by respective torque orders. Camshaft. Cam cam according to one of the preceding claims, characterized in that the cam disks (10, 11, 21) of the vibration damper comprise at least one separate cam disk (21). The drive wheel 9 is arranged between the ends 13, 14 of the camshaft, and the cam disks 10, 11, 21 of the vibration damper are of the camshaft end 13. And at least one separate cam disk (21) on or near one or both sides of (14). 5. The drive wheel (9) according to claim 1, wherein the drive wheel (9) is arranged at or near one of the ends of the cam shaft, and the cam discs (10, 11, 21) of the vibration damper are at the cam shaft end. And at least one separate cam disk (21) at or near the other one of the (13,14). The cam disk (10, 11, 21) of the vibration damper according to any one of the preceding claims comprises a cam disk (10) for driving fuel pumps, wherein the vibration damping portion of the cam disk operates fuel injection. Cam shaft, characterized in that it is disposed substantially outside of the circumferential surface portions 17,18 of the cam disk. The cam disks 10, 11, 21 of the vibration damper comprise a cam disk 11 for driving an exhaust valve, wherein the vibration damping portion of the cam disk continuously drives the valve. A cam shaft, which is disposed outside a portion of the circumferential surface of the cam disk to be opened and closed. The cam disk (10, 11, 21) of the vibration damper according to any one of the preceding claims, characterized in that it comprises cam disks with vibration damping portions adapted to sufficiently compensate for undesirably large vibration modes. Camshaft.