EP1591629A1 - Cam with a groove for controlling the rotation of a tappet - Google Patents

Abstract

A cam (2) is provided with a cam lug (3). The cam enables the oscillating reciprocating movement of a cam follower (11). The central plane (5) of the cam is arranged offset with respect to the longitudinal axis (12) of the cam follower. A circumferential direction groove (7) is formed at the outer face of the cam in an area of the cam lug.

Description

The invention relates to a system comprising a cam with a cam nose and a cam follower, which upon rotation of the cam a oscillating stroke movement in the direction of its longitudinal axis, either the center plane of the cam, which is perpendicular to the axis of rotation of the cam, relative to the longitudinal axis of the cam follower element by an eccentricity E1 is arranged offset, or on the one hand, a contact surface of the follower element Crown and on the other hand the cam has a cam bevel with regard to it Having an axis of rotation, so that the cam follower element rotates about its longitudinal axis, when the cam extends with its cam surface along a contact line engaged with the cam follower.

Furthermore, the invention relates to the use of such a system.

A system of the type mentioned above, for example, in an internal combustion engine used a motor vehicle. A four-stroke working method comprises in addition to the compression of the fuel air mixture or the combustion air and the expansion due to the combustion taking place in the combustion chamber and the Charge exchange. As part of the charge change, the pushing out of Combustion gases via the exhaust valves and the filling of the combustion chamber with Fresh mixture or fresh air via the intake valves. To control the Charge changes in four-stroke engines are almost exclusively globe valves used, which oscillates during operation of the internal combustion engine Execute lifting movement and in this way the opening and closing operation perform the inlet and outlet openings.

The required actuating mechanism including the valves is called Valve gear designates. It is the task of the valve train, the intake and To release exhaust ports of the combustion chamber in time or close, where a quick release of the largest possible flow cross-sections is sought to to keep the throttling losses in the inflowing and outflowing gas flows low and the best possible filling of the combustion chamber with fresh mixture or a effective i. ensure complete expulsion of the combustion gases.

According to the prior art, a valve is used for this purpose in the rule along its longitudinal axis between a valve closing position and a Valve open position is movable to an inlet or outlet opening of a Release combustion chamber of the internal combustion engine or block. to Actuation of the valve on the one hand valve springs are provided to the Prevent valve in the direction of valve closing position, and on the other Valve actuator used to the valve against the biasing force to open the valve spring means.

The valve actuating device comprises a camshaft on which a plurality of Cam is arranged and - for example by means of a chain drive - of the crankshaft is rotated in the manner that the camshaft and with this orbits the cam at half the crankshaft speed.

Basically, between an underlying camshaft and a distinguished overhead camshaft.

Bottom camshafts are suitable for the actuation of so-called standing valves, but also with the help of bumpers and levers, For example, swing levers or rocker arms, hanging for the operation Valves. Standing valves are opened by moving them upwards, whereas hanging valves are opened by a downward movement. there usually a plunger is used as an intermediate element, at least during the opening and closing operation with the cam of the camshaft in Engaged.

On the other hand, overhead camshafts are exclusively for actuation used overhead valves, wherein a valve train with overhead camshaft as another valve drive component a rocker arm, a rocker arm or a Tappet has. The rocker arm rotates about a fixed pivot point and When displaced by the cam, the valve moves against the preload force the valve spring means towards the valve open position. When a rocker arm, the order a centrally located pivot point is pivotally, the cam engages the an end of the rocker arm, wherein the valve at the opposite end of the Levers is arranged.

When using a plunger, this plunger is on the combustion chamber remote end of the lift valve placed so that the plunger on the oscillating stroke movement of the valve participates when the cam is with his Cam surface in the area of the cam nose along a contact line in Intervention is with the plunger.

An advantage of using overhead camshafts is that in particular by the omission of the bumper the moving mass of Valve gear is reduced and the valve gear rigid i. less elastic.

The contour of the cam high demands are made. For one thing, the Cam - as already mentioned above - a fast opening and closing of the valves and thus a quick release of the largest possible flow cross sections guarantee. On the other hand, it must be considered that the valve train elastic mass system is that due to the oscillating motion in particular the valve and the plunger high accelerations and Delays is exposed. In particular, a lifting of the cam from the plunger at higher speeds should be avoided. An exact mathematical Description of the valve train is very complex and the mathematical representation the ram rotation is feasible only in beginnings. At this point, but a few essential issues to be addressed for the understanding of Present invention are indispensable.

When the cam engages the plunger, the cam slides with it Cam shell surface along a line of contact on the surface of the plunger from. The rotational movement of the cam has a lifting movement of the plunger for Episode. To facilitate slipping and wear of both components minimize, the contact zone between cam and plunger with lubricating oil provided. As a result of the relative movement of the two components to each other forms by the hydrodynamics dependent on the angle of rotation a different load-bearing Lubricating film between the cam surface and plunger surface. The structure This lubricating oil film is comparable to the structure of the lubricating oil layer in one Plain bearing, in the present case the number of lubricants, which is a measure of the Carrying capacity of the lubricating oil film does not represent the difference of the relative Component speeds depends, but on the sum of the relative Component speeds.

The wear of the cam and pestle is not only disadvantageous in terms of the Life of these components, but also in particular in terms of Functioning of the valve train. A material removal on the Cam surface and / or the plunger surface has in fact an influence on the valve clearance and on the other effects on the valve lift and the Control times i. on the crank angle to which the valve is opened and is closed.

Another measure to counteract the wear of plunger and cam, therefore, is to arrange the cam and the plunger to each other in such a way that the center plane of the cam, which is perpendicular to the axis of rotation of the cam, with respect to the longitudinal axis of the plunger around a Eccentricity E _{1 is} arranged offset. This eccentricity causes the plunger to rotate about its longitudinal axis when the cam is engaged with its cam surface along a line of contact with the plunger.

The rotation of the plunger is caused by the left and right of The ram longitudinal axis located portions of the cam surface differently are big. The differently sized cam areas act on the plunger - predominantly - with different sized torques, which is why the plunger is set in rotation due to the difference of these two torques. The Torques result from the product of the pressure point radius, which turns out to be Distance between the respective cam area center of the longitudinal axis of the plunger represents, and the average frictional force resulting from the pressures and the Friction coefficient along the line of contact of the cam portion in the The result is that the average friction force with the pressure point radius as a lever to an equal torque around the longitudinal axis of the plunger leads like the actually occurring along the line of contact with their frictional forces respective levers.

Now, the local pressure along the contact line and thus the local Lubricating number i. the carrying capacity in which between cam surface and Tappet surface forming lubricating oil film - as already mentioned above - from the Sum of the individual relative component speeds dependent, the one to specific time varies locally. Because the component speed of the plunger varies along the contact line d. H. it increases with the peripheral speed increasing radius due to the rotational movement.

The different local peripheral speeds of the rotating ram in turn lead to a changing along the contact line sum of relative component speeds, so that too of those variables dependent parameters, in particular the number of smears, along the contact line to change. Is the sum of the relative component speeds zero is also the Lubricant zero. If then the lubricating oil film is no longer supplied with oil, loses the lubricating film at carrying capacity. This is a limiting case, as it occurs, for example. when the cam surface with the critical Berührradius part of Touch line is.

A decreasing lubricating has basically the disadvantage that with the decreasing bearing capacity of the lubricating film initially increasing the area of Fluid friction is left and a transition to mixed friction takes place, with always decreasing lubricity, the proportion of solid friction always increases more.

Furthermore, it should be noted that the cam surface of the cam a Has in the direction of rotation locally varying radius of curvature, so that the Speed at which the cam slides over the plunger surface, at least changes in the area of the cam nose with the cam rotation angle. Also this effect leads to constantly changing conditions in the lubricating film along the Contact line. Those responsible for the carrying capacity of the lubricating film Parameters change once locally along the contact line and also in Dependence on time

In the experiment, measurements have shown that the ram rotation between the absolute standstill and, for example, 2000 rpm may vary. Be explained this can only be achieved by a likewise greatly changing number of lubricants, i. by a greatly changing the lubricity of the lubricating oil film along the line of contact. The ever-changing condition in the lubricating film along the line of contact ultimately lead to a time-varying, fluctuating Torque around the ram longitudinal axis. This in turn has a lot Non-uniform rotation of the plunger result.

From the non-uniform rotation of the plunger can therefore conclusions be drawn to the friction conditions along the contact line available. The very pronounced fluctuations of the ram rotation let it conclude that the friction conditions also change greatly and the overall Range from pure fluid friction to solid friction.

It can be assumed that there are certain speed ranges for the ram rotation gives, in which a relative optimum of the lubrication conditions between cam and the cam follower element while below and Partial lack of lubrication occurs above this speed window with the result an increased mixed friction due to solid state contact. As the wear with an increasing proportion of solid-state friction also increases Basically as far as possible hydrodynamic lubrication film formation sought between plunger and cam.

It is basically a goal of the designers in designing a valvetrain, To keep the wear between cam and plunger as low as possible.

Against this background, the object of the present invention is a system of the generic type, with those of the prior art known disadvantages are overcome, and in particular a lower Wear has.

Another object of the present invention is to provide uses of show such system.

The first sub-task is solved by a system comprising a cam with a cam lobe and a cam follower, which performs an oscillating lifting movement in the direction of its longitudinal axis with a rotation of the cam, wherein either the center plane of the cam, which is perpendicular to the axis of rotation of the cam, with respect to the The longitudinal axis of the cam follower element is arranged offset by an eccentricity E ₁ , or on the one hand a contact surface of the follower crown and on the other hand, the cam has a cam bevel with respect to its axis of rotation, so that the cam follower element rotates about its longitudinal axis when the cam along with its cam surface along a contact line is in engagement with the cam follower element, and which is characterized in that the cam has at least in the circumferential direction at least in the region of the cam lobe in its cam surface.

The inventive construction of the cam with at least one groove in Circumferential direction is the result of wear tests by means of Radionuclide technology RTM performed on a valve train.

Originally, the engine operating wear of a tribological system of an internal combustion engine for metrological reasons be increased consciously.

As a tribological system, the valve train has become one of the most wear-intensive Systems of an internal combustion engine selected. To the wear of this system In addition, measures were being considered to promote the training of Lubricating oil film between the cam surface and plunger surface difficult and obstruct. These considerations eventually led to the arrangement of a groove in the cam surface of the cam.

The experts took the view that this groove was a suitable tool for the Lubricating oil film between plunger and cam or the formation of the lubricating oil film and thus to adversely affect the carrying capacity of the lubricating oil film. This The assumption was based on the consideration that due to the groove no viable Lubricating oil film could train at least in the region of the groove, as this necessary pressure build-up in the lubricating oil film could not be achieved. A Reduction of the carrying capacity of the lubricating oil film should reduce the proportion of Solid friction along the contact line between plunger and cam increase, which has been effective in view of the desired increase in wear would.

In fact, but then gave a measurement of the wear of plunger and Cam, that the wear, contrary to the assumption of professionals not increased, but clearly d. H. had noticeably decreased. The observed Wear reduction was clearly outside of a basically too estimating measurement uncertainty of the measuring technique used.

It was concluded that the ram rotation was much lower Is subject to speed fluctuations when the cam according to the invention. With a groove is formed. The essential compared to the prior art more uniform rotation of the tappet allows for a more stable lubricating oil film whose wearability varies less vigorously over time than it does conventional cam was observed. The measured lower wear is an indication that the proportion of the Solid friction could be significantly reduced.

As a result, the first object of the invention is achieved, namely a To provide system of the generic type with which the state of the Technology known disadvantages overcome, and in particular one has lower wear.

In addition, with the system according to the invention not only the wear but also the danger of so-called pittings in the Cam shell surface can be lowered.

The so-called pittings are micro-fatigue fractures, the u. a. caused by acting between the cam and plunger Force is not perpendicular to the cam surface, but because of their Friction force component acts more or less obliquely on the cam surface. In the formation of pittings, material is removed from the cam surface detached, so that small craters arise in the cam surface, the technically so disturbed surface to further increase the friction between Tappet and cam leads.

The decrease of the so-called Pittings is further proof that through the inventive design of the cam a - compared to the prior Technology - much more stable and sustainable lubricating oil film between cams and plunger forms, because a viable lubricating oil film leads to a reduced Friction between the components and thus that between the cam and Tappet acting force steeper on the cam surface and the surface of the Cam follower is, whereby straight Pittings are avoided.

Although the investigations were based on the present invention lie, made on a pestle. The results can be without further transmitted, which is why generally of a rotating element, which operated by the cam, i. is distracted, can be spoken.

But are advantageous embodiments of the system in which the Cam follower is a plunger or a washer which the Moves stroke movement to another transmission element.

Embodiments of the system have proved to be advantageous in which | E ₁ | ≤ 0.5 NB, where NB denotes the width of the cam in the direction of its longitudinal axis.

Particularly advantageous embodiments of the system, in which | E ₁ | ≤ 0.35 NB, preferably | E ₁ | ≤ 0.25 NB applies.

Advantageous embodiments of the system, in which the center line of the at least one groove with the longitudinal axis of the cam a right angle α = 90 ° i. runs parallel to the median plane of the cam.

In this embodiment, which are located on the left and right of the groove Regions of the cam surface in each case over the entire Camshaft angle range the same size. Ie. the distance of the at least one groove to the center plane of the cam does not change upon rotation of the camshaft.

Different sized cam areas act on the plunger differently high torques. The plunger rotates due to the difference of the different ones Torques. Would the left and right of the groove located Change the cam areas of the camshaft area with rotation of the camshaft, this would lead to a change in the conditions in the lubricating oil film along the Touch line with adverse effects on the ram rotation

Particularly advantageous embodiments of the system, in which the Center line of at least one groove in the center plane of the cam is located. These Placement of the groove leads to a symmetrical design of the cam, which is advantageous in the production and possibly in the assembly of built Camshaft, where the cams are pushed onto the shaft, affects. As a result, for example, not in the direction of the cam during assembly be respected when postponing.

However, embodiments of the system in which the center line of the at least one groove is offset relative to the center plane of the cam by an eccentricity E ₂ are also advantageous. As a result, the effect caused by the eccentricity E ₁ can be enhanced or attenuated.

In this case, embodiments of the system in which | E ₂ | ≤ 0.45 NB, where NB denotes the width of the cam in the direction of its longitudinal axis.

Particularly advantageous are embodiments of the system in which | E ₂ | ≤ 0.35 NB, preferably | E ₂ | ≤ 0.25 NB or | E ₂ | ≤ 0.15 NB.

Also advantageous are embodiments of the system in which E ₁ = - E ₂ applies, so that the center line of the at least one groove is aligned with the longitudinal axis of the element. This embodiment offers advantages because it locates the groove in the region of the plunger surface in which the circumferential speed, which is the product of the angular velocity of the rotating plunger and the distance to the longitudinal axis of the plunger, becomes zero. The point of the plunger surface, which lies on the ram longitudinal axis, namely does not participate in the rotation in the strict sense.

Advantageous embodiments of the system, in which the at least one groove has a width S with S ≤ 0.5 NB, where NB is the width of the cam in the direction designated its longitudinal axis.

Embodiments of the system in which S ≦ 0.35 are particularly advantageous NB, preferably S ≤ 0.25 NB. As a result, the cam surface, which is with the plunger surface engaged, not too much reduced, which is one Wear reduction would be detrimental.

Particularly advantageous embodiments of the system, in which the at least one groove has a width S with S ≥ 0.75 mm. This embodiment contributes to the fact that the groove has a certain minimum width In order to ensure the formation of a viable lubricating oil film in the range of at least to safely prevent a groove.

In certain applications, embodiments of the system are advantageous which have at least one groove over the entire circumference of the Cam shell surface extending annular groove. Especially with valve gears, where the cam not only in the area of the cam nose, but also in the cam nose region of the cam, i. in the area of Base circle of the cam is engaged with the plunger, this is closed annular formation of the at least one groove advantageous to over the entire Scope to realize a reduction in wear.

Particularly advantageous embodiments of the system in which the at least one groove has a depth D with D ≥ 0.8 mm. This embodiment contributes - similar to the requirement for a minimum width S _{min of} the at least one groove - the fact that the groove must also have a certain minimum depth to safely prevent the formation of a viable lubricating oil film in the region of at least one groove.

In the following, two embodiments of the system with their essential dimensions in tabular form are given as examples of the system according to the invention. The numbers are in millimeters. NB E ₁ E ₂ S D B ₁ B ₂ R ₁ R ₂ example 1 14 1.5 2.5 2 0.8 8.5 3.5 1.25 6.75 Example 2 14 1 -1 3 1 4.5 6.5 3.75 4.75

The second of the invention underlying subtask is achieved in that the system is used in a valve train of a piston working machine.

What has already been said for the system according to the invention also applies to the use of the system according to the invention.

For the reasons already mentioned above, uses of the invention are advantageous Systems in which the system is in a valvetrain Internal combustion engine is used.

Also advantageous are uses of the system in which the system as Injection pump operation is used.

Fig.1

schematisch eine erste Ausführungsform des Systems in einer Seitenansicht, und

Fig. 2

schematisch eine zweite Ausführungsform des Systems in einer Seitenansicht.

In the following the invention with reference to two embodiments according to Figures 1 and 2 will be described in more detail. Hereby shows:

Fig.1

schematically a first embodiment of the system in a side view, and

Fig. 2

schematically a second embodiment of the system in a side view.

FIG. 1 schematically shows a first embodiment of the system 1 in one embodiment Side view in a viewing direction perpendicular to the axis of rotation 4 of the Camshaft 9 and perpendicular to the longitudinal axis 12 of the plunger 11 is.

The system 1 comprises a cam 2 with a cam nose 3 and a plunger 11. The cam 2 is arranged on a camshaft 9 and rotates with this Camshaft 9 about its longitudinal axis. 4

The cam 2 and the plunger 11 are arranged to each other in such a way that the center plane 5 of the cam 2, which is perpendicular to the axis of rotation 4 of the cam 2, with respect to the longitudinal axis 12 of the plunger 11 is arranged offset by an eccentricity E ₁ , so that the plunger 11 rotates about its longitudinal axis 12 when the cam 2 engages with its cam surface 6 along a line of contact 10 with the plunger 11.

In the embodiment shown in Figure 1, which corresponds to the Example 1 listed in the table, the eccentricity E ₁ = 1.5 mm.

During operation of the system 1, the cam 2 rotates about its Longitudinal axis 4, while the plunger 11 due to the deflection by the cam second performs an oscillating lifting movement in the direction of its longitudinal axis 12.

A coupled to the plunger 11 valve is characterized along its longitudinal axis between a valve closed position and a valve open position moves and gives while an inlet or outlet opening of a combustion chamber of the internal combustion engine free or blocked this. The plunger 11 moves in deflection by the cam 2 the valve against the biasing force of the valve spring means in the direction Valve open position, wherein the valve by the valve spring means, which the valve in Direction to close valve closing position, is closed again.

The cam 2 is characterized in that it has in the circumferential direction a groove 7 in its cam surface 6, wherein the center line 8 of the groove 7 is arranged offset from the center plane 5 of the cam 2 by an eccentricity E ₂ . In this case, the center line 8 of the groove 7 forms with the longitudinal axis 4 of the cam 2 an acute angle α = 90 °, so that the groove extends parallel to the median plane 5 of the cam 2. In the embodiment shown in Figure 1, the eccentricity E ₂ = 2.5mm, wherein the groove has a width S = 2mm and a depth D = 0.8mm. With a cam width NB = 14mm, therefore, S = 0.14 NB.

The groove 7 divides the cam 2 into two areas. The first, lying to the left of the groove 7 cam area has a width B ₁ = 8.5mm, wherein the distance of the center line of this area to the longitudinal axis 12 of the plunger 11, which corresponds to the radius R _{1 of} the left pressure point, R ₁ = 1, 25mm. The second, lying to the right of the groove 7 cam area has a width B ₂ = 3.5mm, wherein the distance of the center line of this region to the longitudinal axis 12 of the plunger 11, which corresponds to the radius R _{2 of} the right pressure point, R ₂ = 6, 75mm.

The different sized cam areas act on the plunger 11 with different sized torques. The torques result from the product of the respective pressure point radius R ₁ , R ₂ and the respective average friction force F ₁ , F ₂ , which results from the pressures along the contact line 10 of the respective cam portion in such a way that the average friction force F ₁ , F ₂ with the pressure point radius R ₁ , R ₂ as a lever to an equal torque around the longitudinal axis 12 of the plunger 11 as the actually occurring along the contact line 10 pressures or forces with their respective levers.

The fact that the cam 2 is provided with a groove 7, the wear of Tappet 11 and cam 2 compared to the prior art significantly lowered.

Figure 2 shows schematically a second embodiment of the system 1 in one Side view.

In contrast to the embodiment shown in Figure 1, the second embodiment is characterized in that E ₁ = - E ₂ . The eccentricity E ₁ , by which the center plane 5 of the cam 2 is arranged offset with respect to the longitudinal axis 12 of the plunger 11, corresponds in magnitude to the eccentricity E ₂ , about which the center line 8 of the groove 7 is offset relative to the center plane 5 of the cam 2, wherein the eccentricity E _{1 is} positive, ie, directed to the left, whereas the eccentricity E ₁ is directed negative, ie to the right. In this way, the center line 8 of the groove 7 is aligned with the longitudinal axis 12 of the plunger eleventh

Benefits of this embodiment, because so that the groove 7 in the field of Plunger surface is arranged, in which the peripheral speed, resulting from the product of angular velocity of the rotary ram 11 and the Distance to the longitudinal axis 12 of the plunger 11 results in zero. The point of Plunger surface, which lies on the ram longitudinal axis 12, does not take part in the rotation part, why it is advantageous if the cam 2 at the point at which he along the Touch line 10 moves over the ram longitudinal axis 12, a groove 7 has.

Otherwise, reference is made to Figure 1. For the same components were the same reference numerals used. The embodiment shown in Figure 2 corresponds to the example given in the table 2.

reference numeral

1

system

2

cam

3

cam lobe

4

Longitudinal axis, axis of rotation of the cam

5

Center plane of the cam

6

Cam outer surface

7

groove

8th

Centerline of the groove

9

camshaft

10

Contact line between cam and element

11

Cam follower element, element, ram

12

Longitudinal axis of the element

α

Angle between the centerline of the groove and the longitudinal axis of the cam

B ₁

Width of the left of the groove cam area

B ₂

Width of the cam area to the right of the groove

D

Depth of the groove

E ₁

Eccentricity of the center plane of the cam with respect to the longitudinal axis of the cam element

E ₂

Eccentricity of the center line of the groove relative to the center plane of the cam

F ₁

average friction force

F ₂

average friction force

NB

Width of the cam in the direction of its longitudinal axis

R ₁

Radius of the left pressure point from the longitudinal axis of the element

R ₂

Radius of the right pressure point from the longitudinal axis of the element

S

Width of the groove

S _min

minimum width

Claims (23)

System (1) comprising a cam (2) with a cam lobe (3) and a cam follower element (11), which performs an oscillating lifting movement in the direction of its longitudinal axis (12) upon rotation of the cam (2) either the center plane (5) of the cam (2), which runs perpendicular to the axis of rotation (4) of the cam (2), is arranged offset from the longitudinal axis (12) of the cam follower element (11) by an eccentricity E ₁ , or on the one hand a contact surface of the follower element (11) has a crown and on the other hand the cam (2) has a cam bevel with respect to its axis of rotation (4), such that the cam follower element (11) rotates about its longitudinal axis (12) when the cam (2) engages with its cam surface (6) along a contact line (10) with the cam follower element (11), characterized in that the cam (2) in the circumferential direction at least in the region of the cam nose (3) has at least one groove (7) in its cam surface (6). System (1) according to claim 1,
characterized in that
the cam follower element (11) is a plunger (11). System (1) according to claim 1,
characterized in that
the cam follower element (11) is a washer. System (1) according to one of the preceding claims,
characterized in that
| E1 | ≤ 0.5 NB, where NB denotes the width of the cam (2) in the direction of its longitudinal axis (4). System (1) according to claim 4,
characterized in that
| E1 | ≤ 0.35 NB. System (1) according to claim 4 or 5,
characterized in that
| E1 | ≤ 0.25 NB. System (1) according to one of the preceding claims,
characterized in that
the center line (8) of the at least one groove (7) forms a right angle α = 90 ° with the longitudinal axis (4) of the cam (2), ie runs parallel to the center plane (5) of the cam (2). System (1) according to claim 7,
characterized in that
the center line (8) of the at least one groove (7) lies in the median plane (5) of the cam (2). System (1) according to claim 7,
characterized in that
the center line (8) of the at least one groove (7) is arranged offset from the center plane (5) of the cam (2) by an eccentricity E2. System (1) according to claim 9,
characterized in that
| E2 | ≤ 0.45 NB, where NB denotes the width of the cam (2) in the direction of its longitudinal axis (4). System (1) according to claim 10,
characterized in that
| E2 | ≤ 0.35 NB. System (1) according to claim 10 or 11,
characterized in that
| E2 | ≤ 0.25 NB. System (1) according to one of claims 10 to 12,
characterized in that
| E2 | ≤ 0.15 NB. System (1) according to one of the preceding claims,
characterized in that
E1 = - E2 holds, so that the center line (8) of the at least one groove (7) is aligned with the longitudinal axis (12) of the cam follower element (11). System (1) according to one of the preceding claims,
characterized in that
the at least one groove (7) has a width S with S ≤ 0.5 NB, where NB denotes the width of the cam (2) in the direction of its longitudinal axis (4). System (1) according to claim 15,
characterized in that
S ≤ 0.35 NB. System (1) according to claim 15 or 16,
characterized in that
S ≤ 0.25 NB. System (1) according to one of the preceding claims,
characterized in that
the at least one groove (7) has a width S with S ≥ 0.75 mm. System (1) according to one of the preceding claims,
characterized in that
the at least one groove (7) is an annular groove (7) extending over the entire circumference of the cam surface (6). System (1) according to one of the preceding claims,
characterized in that
the at least one groove (7) has a depth D with D ≥ 0.8 mm. Use of a system (1) according to one of the preceding claims,
characterized in that
the system (1) is used in a valve train of a piston working machine. Use of a system (1) according to one of claims 1 to 20,
characterized in that
the system (1) is used in a valve train of an internal combustion engine. Use of a system (1) according to one of claims 1 to 20,
characterized in that
the system (1) is used as an injection pump operation.

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