EP0807206B1 - Internal combustion engine - Google Patents

Description

The invention relates to an internal combustion engine in which the speed of rotation of a cam Gas exchange control is cyclically changeable by a Intermediate link in a plane perpendicular to the axis of rotation a camshaft slidable and in any position is rotatable within this plane.

A rotary drive arrangement that cyclically variable cam movement is not in the Pre-published German patent application 195 01 172.4 is disclosed, the disclosure content of which by explicit reference in the present application is recorded.

Such a rotary drive arrangement is preferably used for driving cams to control an intake or Exhaust valve of an internal combustion engine. Here will caused by the rotary drive arrangement that at a constant speed of rotation of the internal combustion engine of the cam changed cyclically by an average speed becomes. The degree of change, i.e. the amount of temporary increase in angular velocity and temporarily lowering the angular velocity of the Nockens and the phase of these changes depend on the position that an intermediate link has with respect to a Driveshaft. With a concentric position of the Intermediate link with respect to the drive shaft rotates the cam synchronous with the drive shaft. The further that Intermediate link from this concentric position in a radial Direction is shifted, the greater the cyclical Speed change, the phase position of the Direction of displacement of the pontic and the depends on the respective position of the cam. Such a device is known from GB-A-1 311 562.

From the generic Japanese laid-open publication JP 5-118208 it is known in an internal combustion engine Double eccentric for slidably supporting a component to provide that depending on its location a cyclical Changes in the speed of rotation of the cam causes.

The object of the invention is such Engine to run so that the mechanism to cause the cyclical change of the Rotation speed of the cam is compact, inexpensive and easy to manufacture, one stiff storage of the component enables and by simple control means can be actuated.

The solution to this problem is in the claims specified.

The invention, based on a common Inner eccentric two separate outer eccentrics are stored, is particularly suitable for an internal combustion engine a camshaft that is both intake and Exhaust valves drives. This can be a special compact structure can be achieved. The control or Rotation of the inner eccentric and the two External eccentric can have appropriate sprockets take place, the outer eccentrics either separately or can be controlled together.

Fig. 1 eine auseinandergezogene perspektivische Darstellung einer Drehantriebsanordnung zur zyklischen Veränderung der Nockendrehgeschwindigkeit einer Brennkraftmaschine ist,

Fig. 2 eine im Schnitt gehaltene Seitenansicht der Drehantriebsanordnung gemäß Fig. 1 ist,

Fig. 3 ein Schnitt längs der Linie A-A in Fig. 2 ist,

Fig. 4a eine Schnittansicht einer Ausführungsform der Erfindung ist und

Fig. 4b den Zusammenhang der durch die zyklische Geschwindigkeitsänderung der Nocken bewirkten tatsächlichen Ventilerhebungskurven und der Stellung der Exzenter zeigt.

A preferred embodiment of the invention is explained below in conjunction with the accompanying drawings, in which:

1 is an exploded perspective view of a rotary drive assembly for cyclically changing the cam rotation speed of an internal combustion engine,

FIG. 2 is a sectional side view of the rotary drive arrangement according to FIG. 1,

3 is a section along the line AA in FIG. 2,

4a is a sectional view of an embodiment of the invention and

FIG. 4b shows the relationship between the actual valve lift curves caused by the cyclical speed change of the cams and the position of the eccentrics.

A rotary drive arrangement that is cyclical generates variable cam movement, has a shaft 1 with a central axis 5, which in the in the first to 3 shown embodiment of a drive shaft 1st corresponds to these rotary drive regulations. On wave 1 an inner eccentric 30 is mounted, with a for storage Needle roller bearings can be used. As in Fig. 2 shown, the inner eccentric 30 by means of a Thrust washer 38 and a snap ring 39 against Be secured to the left in Fig. 2.

The inner eccentric 30 has a base body 31 and an eccentric seat 32, through which a bore 33 for receiving the shaft 1 runs. The base body 31 has a circular outer contour 37, the central axis of which coincides with the central axis 5 of the shaft 1, which is also the axis of rotation. The outer contour 35 of the eccentric seat 32 has a central axis which is offset by a first eccentricity e ₁ with respect to the central axis of the bore 33 and thus with respect to the axis of rotation 5.

An outer eccentric 40 is rotatable on the outer contour 35 stored. The outer eccentric 40 has a bore 41, those for receiving the outer contour 35 of the eccentric seat 32 the inner eccentric 30 is used.

The outer contour 45 of the outer eccentric 40 is offset from the central axis of the bore 41 by a second eccentricity e ₂ . The eccentricities e ₁ and e ₂ can be chosen freely, but are preferably the same in amount.

An inner eccentric ring gear 34 is non-rotatable with the Outer contour 37 of the inner eccentric 30 connected. Next to the Inner eccentric ring gear 34 is an outer eccentric ring gear 44 arranged, the rotatable on the outer contour 37 of the Inner eccentric 30 is mounted. The External eccentric ring gear 44 has a nose 43 (see FIG. 2), which in a groove 46 of the outer eccentric 40th intervenes.

Rotary drive means (not shown) for controlling the respective rotational position of the inner eccentric 30 and the Outer eccentric 40 can be in the inner eccentric ring gear 34 and engage the external eccentric ring gear 44. Become as control means, for example, two stepper motors selected, the rotary positions of the Inner eccentric 30 and the outer eccentric 40 separately and adjust independently of each other so that the outer contour 45 of the outer eccentric 40 any position within a plane perpendicular to the central axis 5 of the shaft 1 can take.

On the outer contour 45 of the outer eccentric 40 is a Intermediate member 4 rotatably mounted. This intermediate link 4th has a first sliding guide 6 and a second Slideway 7, each for receiving a Slide block 13 are suitable. A first rotating body 2 is rotatably connected to the drive shaft 1 and points a start-up band 2a. On the first rotating body 2 is a formed as a gear second rotating body 3 rotatable stored. The first rotating body 2 has a Bore 11 into which a first designed as a pin Transmission element 8 is introduced. This pin 8 transmits the rotation of the first rotating body 2 via one the sliding blocks 13 and the first sliding guide 6 on the Intermediate link 4.

The second rotating body 3 has a bore 12, in the second designed as a pen Transmission element 9 is introduced. The rotation of the Intermediate member 4 is on the second sliding guide 7 and the other of the two sliding blocks 13 and the pin 9 transferred to the second rotating body 3.

The external eccentric ring gear 44 can extend axially over the External eccentric 40, the intermediate member 4 and the second Support the rotating body 3 against the collar 2a. The federal government 2a first rotating body 2 thus causes the entire Rotary drive arrangement against a shift to the right is secured in Fig. 2.

The second rotating body 3 is designed as a gear that is engaged with a cam gear 22 so that the Rotation of the second rotating body 3 on the camshaft 21 and transmit the cam 20 connected to it in a rotationally fixed manner becomes.

If the intermediate member 4 is in a position in which its central or rotational axis coincides with the central or rotational axis 5 of the drive shaft 1, the second rotary body 3 and thus the cam 20 rotate synchronously with the drive shaft 1 Position is reached when the eccentricities e ₁ and e ₂ are equal in amount and the inner eccentric 30 and the outer eccentric 40 assume such a position that the two eccentricities e ₁ and e ₂ are diametrically opposed.

If now the inner eccentric 30 and / or the outer eccentric 40 about the interior or External eccentric ring gears 34, 44 are rotated, that is Intermediate link 4 in a plane perpendicular to the central axis 5 of the drive shaft 1 moved so that it is on the Outer contour 45 of the outer eccentric 40 about an axis of rotation rotates relative to the central axis 5 of the shaft 1 is offset. As a result, the rotational speed of the second rotating body 3 and thus the cam 20 opposite the rotational speed of the drive shaft 1 cyclically changed.

A complete revolution of the drive shaft 1 has continue one full turn of the second Rotating body 3 and the cam 20 result in the course of this entire turn, however, there is one temporary increase in rotation speed and too a temporary decrease in the rotational speed of the second rotating body 3 and thus the cam 20. Das Extent of this increase in rotational speed or Rotation speed reduction depends on the offset of the Axis of rotation of the intermediate member 4 with respect to the central axis 5 of the drive shaft 1. The direction of this offset determines the phase position of the respective increase in rotational speed or reduction in rotational speed regarding the position of the cam 20.

4a shows an embodiment of the invention. This differs from that explained above Rotary drive arrangement in that on a common Inner eccentric 30 two outer eccentrics 40A, 40B arranged are. The inner eccentric 30 can Inner eccentric ring gear 34 are rotated while the External eccentric 40A, 40B over corresponding External eccentric gear rings 44A, 44B either separately or can be controlled together. On each of the two An intermediate member 4 is mounted on the outer eccentric 40A, 40B.

Another difference is that the Inner camshaft running the camshaft of the Is internal combustion engine and that the rotation of each Transfer link 4 directly to a cam which in turn can be rotated directly on the camshaft is stored. These cams can either be two intake or two exhaust cams of one cylinder act simultaneously or independently of each other can be varied in terms of their rotational speed can, but two can not be the same Cams, i.e. an intake cam and an exhaust cam are driven. This makes it possible for a Internal combustion engine with only one camshaft under Use of a common inner eccentric 30 a one and affect an exhaust valve together.

The latter case is shown in Fig. 4a, where the letters IN the inlet cams and the letters EX designate the exhaust cam. If for the rotation of the Inner eccentric 30 and the two outer eccentrics 40A, 40B separate control means (not shown) are provided, with a suitable choice of respective eccentricities and the positions of both Eccentric seats on the common inner eccentric 30 one extensive independence of the variations of the Control times and the valve opening duration of both valves given.

However, it is also one of the essential requirements the internal combustion engine Possibility of variation of the two valves in the case given in which the two outer eccentrics 40A, 40B can be controlled or rotated together. This will compared to the case of independent control of both External eccentric 40A, 40B a control means (not shown) saved. The prerequisite for this, however, is that the Eccentricities, i.e. the positions of the two Eccentric seats of the common inner eccentric to each other, meet certain requirements.

For this purpose, the related relationships are explained.

The cyclical change in the rotational speed results from the fact that, due to the axial offset of the central axes of rotation of the camshaft and the intermediate member, depending on the angular position, different driving radii r occur between the camshaft and the intermediate member on the one hand and the intermediate member and the cam on the other hand. At the connection point between the camshaft and the intermediate element, ie the point of engagement of the first transmission element in the first sliding guide, the condition that the tangential speed component v _tan must be constant at a constant rotational speed w _NW also applies because the distance r _{NW of} this point of engagement from the axis of rotation of the camshaft always remains constant.

From the equation v tan = w NW · R NW = w ZW · R ZW it follows that the angular velocity w _{ZW of} the intermediate member changes when the distance r _{ZW of} the point of engagement to the axis of rotation of the intermediate member changes.

As a result, the intermediate member and thus also the Cams once with a full revolution of the camshaft faster and once slower than the camshaft. On the points at which the speed difference is greatest between the cam and the camshaft, is the lead or lag of the cam opposite the camshaft is zero. Cut at this point the output valve lift curve, i.e. the Valve lift curve, which is at a concentric Position of the intermediate link, and the modified valve lift curve, i.e. the Valve lift curve, which at the respective Axial offset between the axis of rotation of the intermediate link and the axis of rotation of the camshaft.

Fig. 4b shows the valve lift curves in the on the Field of internal combustion engines usual representation, where OT is the top dead center of the piston, AM is the distance between the middle of the outlet and TDC, i.e. the outlet spread, and EM the distance between the center of the inlet and TDC, i.e. the Intake spread is. The one drawn in Fig. 4b Phase angle ϕ is the angle between the maximum of modified cam speed, i.e. the Intersection of the respective output valve lift curve with the modified valve lift curve, and the Output valve lift curve maximum. Positive values of the phase angle ϕ mean that the modified Valve lift curve in the direction of increasing Cam flank is shifted, and mean negative values a shift towards the falling cam flank.

Since the aim is to reduce the overlap at low speeds for the purpose of changing the charge of the internal combustion engine, the value of the phase angle ϕ _{IN of} the intake cam IN is preferably positive and the value of the phase angle ϕ _{EX of} the exhaust cam EX is preferably negative.

The phase angle is determined by the choice the direction of displacement of the eccentricity with the respective position of the cam tip to the Valve actuator, for example one Tappet. With a suitable choice of the arrangement of the two eccentric seats of the common inner eccentric 30 and a corresponding starting position of the two External eccentrics 40A, 40B cause both to rotate External eccentric 40A, 40B in the same direction that the Overlap area is increased or decreased, i.e. the two modified Valve lift curves towards or away from each other move.

Such a configuration is schematic in Fig. 4b shown, the representation under I den Inlet cam and the representation under II den Exhaust cam affects. The center white circle represents the Camshaft, the black surface the inner eccentric and the hatched area represents the external eccentric.

In the configuration shown, the eccentricity e _{1 of} the eccentric seat for the inlet cam IN of the common inner eccentric, as viewed from the axis of rotation of the camshaft, runs approximately 45 ° downward to the left and the eccentricity e _{2 of} the outer eccentric 40B runs exactly in the opposite direction, so in the starting position that in this starting position the resulting eccentricity e for the intermediate member of the inlet cam IN is zero.

The eccentricity e _{1 of} the eccentric seat for the exhaust cam EX of the common inner eccentric extends from the axis of rotation of the camshaft approximately 45 ° to the top left and the eccentricity e _{2 of} the outer eccentric 40A runs exactly in the opposite direction, so that in this starting position the resulting eccentricity e for the intermediate member of the exhaust cam EX is also zero.

A rotation of the common inner eccentric 30 in the direction of arrow α clockwise by 90 ° and a simultaneous rotation of both outer eccentrics 40A, 40B in the direction of arrow β counterclockwise causes a maximum eccentricity e _max for the intermediate member of the inlet cam IN = e ₁ + e _{2 seen} from the axis of rotation of the camshaft in a direction approximately 45 ° to the top left and for the intermediate member of the exhaust cam EX a maximum eccentricity e _max = e ₁ + e _{2 seen} from the axis of rotation of the camshaft in one direction about 45 ° to the top right. The angles ϕ _IN and ϕ _EX therefore have a different sign.

This achieves the desired effect that a rotation of the two external eccentrics in one direction the modified valve lift curves towards each other or can be moved away from each other, so that the Overlap area can be changed.

It should be noted that the offset of the eccentric seats of the common inner eccentric 30 from one another results in the sum of the phase angles ϕ GES = ϕ IN + ϕ EX is set. Within this boundary condition, however, a free choice of the phase angles ϕ _IN and im _EX is possible during operation of the internal combustion engine by a corresponding choice of the direction of displacement of the intermediate elements.

Further variation possibilities result from the Possibility of different individual eccentric surveys and different gear ratios in the Rotations of the eccentrics for the different cams to provide.

By using a meshing one Spur gear pair, in which one of the spur gears with the Internal eccentric and the other spur gear with the or External eccentrics, the previous explained opposite rotation with a single Actuate servomotor.

Reference list

1

Shaft, drive shaft

2nd

first rotating body

2a

Federation

3rd

second rotating body

4th

Pontic

5

Central axis, axis of rotation

6

first sliding guide

7

second sliding guide

8th

first transmission element, pin

9

second transmission element, pin

11

drilling

12th

drilling

13

Sliding block

20th

cam

21

camshaft

22

Cam gear

30th

Internal eccentric

31

Basic body

32

Eccentric seat

33

drilling

34

Internal eccentric ring gear

35

Outer contour

37

Outer contour

38

Thrust washer

39

Snap ring

40

External eccentric

41

drilling

43

nose

44

External eccentric ring gear

45

Outer contour

46

Groove

e ₁

first eccentricity

e ₂

second eccentricity

Claims (9)

1. An internal combustion engine in which the rotational speed of a cam for gas exchange control can be cyclically varied, said internal combustion engine comprising

   a cam shaft having an axis of rotation;

   a cam rotatably supported on said cam shaft;

   an intermediate member (4) which can be moved in a plane perpendicular to said axis of rotation of said cam shaft and which is rotatably supported in any position within said plane and which has a first sliding guide and a second sliding guide;

   a first transmission element connecting said cam shaft to said first sliding guide to transmit the rotary motion of said cam shaft to said intermediate member (4); and

   a second transmission element connecting said cam to said second sliding guide to transmit the rotary motion of said intermediate member (4) to said cam;

   so that, in one rotation of said cam shaft, said cam is cyclically rotated in relation to said cam shaft if said axis of rotation of said intermediate member (4) is in an offset position to said axis of rotation of said cam shaft; said internal combustion engine further comprising

   an inner eccentric element (30) rotatably supported on said cam shaft; and

   an outer eccentric element (40) rotatably supported on said inner eccentric element (30);

   wherein said intermediate member (4) is rotatably supported on said outer eccentric element (40);

   - characterized in that
   two outer eccentric elements (40A, 40B) are provided on one inner eccentric element (30).
2. Internal combustion chamber as claimed in claim 1, characterized in that the second eccentricity (e₂) of said outer eccentric element (40) is equal to the first eccentricity (e₁) of said inner eccentric element (30).
3. The internal combustion chamber as claimed in any of the proceeding claims, characterized in that said inner eccentric element (30) comprises an inner eccentric gear ring (34) rigidly fixed thereupon.
4. The internal combustion engine according to any of the proceeding claims, characterized in that said inner eccentric element (30) has a circular outer contour (37), the central axis of which coincides with the central axis of the bore (33) for encompassing said camp shaft and that an outer eccentric gear ring (44) for controlling said outer eccentric element (40) is supported on said outer contour (37).
5. The internal combustion engine as claimed in claim 4, characterized in that said outer eccentric gear ring (44) has a projection (43) which is in engagement with a groove (46) of said outer eccentric element (40).
6. The internal combustion engine as claimed in any of the proceeding claims, characterized in that one of said outer eccentric elements (40A) is connected to an intake cam (IN) and the other outer eccentric element (40B) is connected to an exhaust cam (EX).
7. The internal combustion engine as claimed in any of the proceeding claims, characterized in that both outer eccentric elements (40A, 40B) can be commonly controlled.
8. The internal combustion engine as claimed in claim 7, characterized in that both eccentric seats of said common inner eccentric element (30) are disposed in a way and both outer eccentric elements (40A, 40B) are disposed on said both eccentric seats of said common inner eccentric element (30) in a way that if both outer eccentric elements (40A, 40B) on the one hand and said common inner eccentric element (30) on the other hand are rotated in opposite directions, the modified valve lift curves move towards each other.
9. The internal combustion engine as claimed in any of the proceeding claims, characterized in that by use of an engaging cylindrical gear pair wherein one of said two cylindrical gears is connected to said inner eccentric element and the other cylindrical gear is connected to said outer eccentric element or said outer eccentric elements, the rotation in opposite directions can be effected by a single servo motor.

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