WO2012130487A2

WO2012130487A2 - Device for discrete phase shifting

Info

Publication number: WO2012130487A2
Application number: PCT/EP2012/050606
Authority: WO
Inventors: Michael Breuer; Andres Tönnesmann; Andreas Köster; Costantino Brunetti
Original assignee: Pierburg Gmbh
Priority date: 2011-03-29
Filing date: 2012-01-17
Publication date: 2012-10-04
Also published as: WO2012130487A3; DE102011001612B4; DE102011001612A1

Abstract

Devices for phase shifting between a drive wheel and an output shaft are known, wherein a torque to be introduced into the system is exerted on the output shaft for adjustment. Therefore the invention relates to a device having a drive wheel (2), a coupling mechanism (10), an output shaft (4) which is driven via the coupling mechanism (10), and an actuator (58), wherein, upon actuation of the actuator, the angle of rotation of the drive wheel with respect to the output shaft can be moved via the coupling mechanism. A four-bar linkage (10) having two axles (8, 24) which are immovable relative to the drive wheel (2) and two axles (14, 18) which are movable relative to the drive wheel (2) serves as a coupling mechanism. The four-bar linkage (10) has a cam (12), the axis of rotation of which is a first one of the immovable axles (8) and the cam output axis (14) is a first one of the movable axles. A roller (20) or a gear wheel is disposed on a second one of the movable axles (18), which revolves selectively in one of at least two contours (46, 50, 54), which are movable relative to the roller (20) or the gear wheel, the roller (20) or the gear wheel being loaded by means (36; 32) for pressing against the contour (46, 50, 54). In such an embodiment the energy requirement is substantially reduced.

Description

DESCRIPTION

Device for discrete phase shift

The invention relates to a device for discrete phase shift of a rotational angle between a drive wheel and an output shaft with a drive wheel, a coupling gear, an output shaft which is driven via the coupling gear and an actuator, in the actuation of the rotational angle of the drive wheel to the output shaft via the coupling gear is displaceable ,

Phase shifting devices are used, for example, to shift the angle of rotation between a crankshaft and a camshaft of an internal combustion engine. Also, such devices can be used in internal combustion engines for cycle accurate control of an exhaust gas recirculation system. The phase shift is used for variable valve timing to improve the combustion process in the engine. For phase shift of the camshaft, for example, vane-cam phaser, camshaft chains are verstellor or axially displaceable

Gear elements known. Advantageous electrical phasing have been found, which must be energized as possible only in the periods in which an adjustment is required.

Thus, in US 5,680,836 discloses a device for phase shifting between a camshaft and a crankshaft with a planetary gear. Here, a planet carrier is fixedly mounted on a camshaft, wherein the planetary gears with the sun gear and an internal toothing of a drive wheel are engaged. The drive wheel is driven via a chain drive in a fixed transmission ratio via the crankshaft, for example. A Angle adjustment takes place in this embodiment by rotating the sun gear by means of an actuator. A disadvantage of such a design is that for holding the sun gear, an electric actuator must be supplied with voltage, since there is no self-locking of the drive. Accordingly, there is a high permanent energy requirement.

Another device for angular adjustment of a shaft relative to a drive wheel is known from DE 197 06 855 AI. In this device is an eccentrically arranged actuator in the power flow between the drive wheel and the output shaft, the connection can be solved by a clutch. The actuator consists of a two pivot axes connecting rocker, wherein the pivot axes are formed by pins which are guided in slots. In the rotary angular adjustment of the first pin is moved on a radial straight line while the second pin is moved along a EUipsenUnie, whereby a relative rotation between the drive wheel and the output shaft is formed. However, this arrangement is very limited in terms of the maximum adjustment angle by a necessary window in a flange which is arranged on the output shaft. In addition, a synchronization between the gears for adjustment is required. The adjustment of the actuating element takes place hydraulically due to the eccentric arrangement. This hydraulic pressure must be provided over the entire adjustment period.

In the known embodiments, a force is thus applied during the entire adjustment process and often also from the outside. Accordingly, there is a high energy demand. The actuator to be used must be designed to be large enough to apply the necessary restoring forces. It is therefore an object to provide a device for discrete phase shift of the angle of rotation between a drive wheel and an output shaft, in which the mechanical load of the actuator and at the same time the energy requirement of the actuator are minimized. The device should be robust while requiring only a small amount of space.

This object is achieved by a device for phase shifting the angle of rotation between a drive wheel and an output shaft having the features of the main claim.

Characterized in that serves as a coupling mechanism, a four-bar linkage with two axes fixed to the drive wheel and two axes movable relative to the drive wheel, wherein the four-bar linkage has an eccentric whose axis of rotation is a first of the stationary axes and whose Exzenterabtriebsachse is a first of the movable axes and on a second the movable axles are arranged a roller or a gear, which optionally rotates in one of at least two contours, which are movable relative to the roller or to the gear wheel, wherein the roller or the gear is loaded by means for pressing against the contour, it will possible to remove a torque required for adjusting the phase angle alone from the drive torque of the drive wheel. An energy input is only briefly to introduce axial displacement of the contours, while in the course of the rotation angle adjustment no additional energy must be introduced. Correspondingly, smaller actuators can be used. Furthermore, the energy consumption decreases due to the shorter operating periods.

Preferably, a first of the at least two contours is a circular contour. While the roller or the gear runs in this circular contour, there is no adjustment of the angle of rotation, since the eccentric is not rotated by the circular contour to the drive wheel. Accordingly, the Corresponding diameter of the circle of the envelope of the roller or the gear in a movement in which the position of the eccentric remains unchanged relative to the drive wheel.

In a further embodiment of the invention, a second and third contour have rotational angle ranges whose diameter is greater or smaller than that of the circle of the first contour and rotational angle ranges which have the same diameter as the circle of the first contour. The area of the same diameter serves as a synchronization area, in which the pass can be changed from one contour to the other. The other rotation angle ranges produce in a four-bar linkage rotation of the Exzenterabtriebsachse relative to the drive wheel. Thus, however, the output shaft is also rotated by a corresponding angle. This means that during one revolution of the roller on the contour the

15 output shaft is rotated by a fixed angle to the drive wheel, which means that per revolution, a discrete adjustment takes place.

Preferably, the first stationary axis of the four-bar link is formed by a first shaft, which is rotatably mounted in the drive wheel and auf0 of the eccentric is arranged. On the eccentric a first connecting rod is rotatably mounted, at the opposite end a second shaft is rotatably mounted, on which the roller or the gear and a second connecting rod are rotatably mounted and which serves as a second movable axis. At the opposite end 5 of the second connecting rod, a third shaft is rotatably supported, the opposite end of which is secured to the drive wheel and serves as the second stationary axle to the driving wheel. Thus, the required four-joint is realized in a simple manner. 0 In a further embodiment, the first shaft is centrally rotatably mounted in the drive wheel. This facilitates the storage of the eccentric shaft, whereby the life of the device is increased. In a further embodiment, a gear is rotatably fixed to the first time, which is coupled via a reduction gear to the output shaft. Thus, the required reduction is realized in a simple manner.

A particularly simple form of adjustment results when the contours are arranged one behind the other and are axially displaceable by the actuator.

In a further development of the invention, the device has a second four-bar link, whose two stationary axes and whose first movable axis correspond to the axes of the first four-bar linkage and on the second movable axis of a second roller or a second gear is rotatably mounted, the or in to orbits corresponding to the first contours. This second four-bar joint reduces the degrees of freedom of the movement of the roller, so that a necessary for correct function rolling of the roller on the contour is largely ensured.

In order to continue to use only one actuator, the other contours are axially adjustable together with the first contours on the actuator. Thus, a synchronization is ensured during the movement.

In a preferred embodiment, the means for pressing the roller or the gear against the contour are formed by a spring element. This pushes the role against the contour, which is ensured in a particularly simple manner, the rolling of the roller or the gear on the contour. Preferably, the spring element biases the connecting rods mounted on the second stationary shaft to the outside. In this way, the spring element is arranged particularly simple and easy to install. It is particularly advantageous if a helical spring is arranged as a spring element about the second stationary axis, whose spring limbs are prestressed against abutments which are arranged on the connecting rods rotatably mounted on the second stationary axis. This type of arrangement of the spring element is simple and therefore inexpensive to carry out.

It is thus provided a device for discrete phase shift of the rotational angle between a drive wheel and a AbtriebsweJfe, in which the energy requirement of the actuator is minimized, since both low Stell forces are necessary and the Verstelizeiten are extremely short. The torque for adjusting the Drehwinkeis is completely removed from the drive torque of the drive wheel. The entire production and assembly remains cost feasible.

An embodiment of a device according to the invention for the discrete phase shift of the rotational angle between a drive wheel and an output shaft is shown schematically in the drawings and will be described below.

FIG. 1 shows a side view of a device according to the invention for the discrete phase shift in a schematic representation.

Figure 2 shows a top view of the device of Figure 1 without contours in a schematic representation.

FIG. 3 shows schematically a comparison of the different contours. The illustrated in the figures embodiment of a discrete phase shift device according to the invention consists of a drive wheel 2, which may for example be designed as a chain nritzel and coupled via a chain with a crankshaft of an internal combustion engine. This drive wheel 2 is mounted on an output shaft 4, which according to the invention can be rotated in discrete steps to the drive wheel 2 in order to realize a phase shift of the opening times of the intake valves to the rotational angle of the crankshaft and which serves as an axis during the rotation of the drive wheel 2.

At the drive wheel 2 in the radially outer region of a bearing point 6 is formed in which a first time 8 is mounted, which serves as the first stationary to drive wheel 2 axis of a coupling mechanism serving as four-bar linkage 10. This fixed to the drive wheel 2 axis is simultaneously the axis of rotation of an eccentric 12 which is mounted on the first shaft 8 and whose Exzenterabtriebsachse 14 is thus rotated about the first stationary axis of rotation. This Exzenterabtriebsachse 14 serves as the first to the drive wheel 2 movable axis of the four-bar 10th

On the eccentric 12 in turn rotatably about the Exzenterabtriebsachse 14, a first connecting rod 16 is arranged, the opposite end is rotatably mounted on a second shaft 18 which serves as the second drive wheel 2 movable axis of the four-bar linkage 10 and on the additionally rotatably mounted a roller 20 is. On the second shaft 18, a first end of a second connecting rod 22 is further arranged, whose opposite end encloses a third shaft 24, which serves as a second stationary axis of the four-bar 10 and which is also secured in the drive wheel 2. As can be seen in particular in FIG. 2, this third shaft 24 is arranged substantially on the side of the drive wheel 2 opposite the first shaft 8. On this third shaft 24, a third connecting rod 26 is additionally supported, the opposite end is in turn mounted on a fourth shaft 28 on which a second roller 30 is additionally mounted and which serves as a second movable axis to the drive wheel of a second four-bar link 32, the first movable axis in turn is the Exzenterabtriebsachse 14, with which the fourth shaft 28 is rotatably connected by means of a fourth connecting rod 34. To the third shaft 24, a spring element 36 is arranged in the form of a helical spring, the two spring legs 38, 40 bear against stops 42, 44. These stops 42, 44 are arranged in the form of bolts on the two attached to the third shaft 24 connecting rods 22, 26. The spring element is arranged such that the two connecting rods 22, 26 spread apart from each other and thus the two rollers 20, 30 are pressed outwardly against a respective contour 46, 48, 50, 52, 54, 56, thereby ensuring that this both rollers 20, 30 on the contours 46, 48, 50, 52, 54, 56 unroll and not stand out from these.

For each roller 20, 30 each include three different contours 46, 48, 50, 52, 54, 56, which are arranged axially one behind the other and can be moved together via an actuator 58 in the axial direction. In each case one of these contours 46, 48 is circular. The axial spacing of these contours 46, 48 corresponds to the axial spacing of the rollers 20, 30, so that the rollers 20, 30 always run simultaneously in the associated circular contour 46, 48.

The further contours 50, 52, in the present exemplary embodiment, as can be seen in FIG. 3, have a shape modified relative to the circular contour 46, 48, in which the distance to the center in a rotation angle range 60 is slightly larger. In addition are in a further rotation angle range 62 of approximately 90 °, the circular contours 46, 48 modeled. The contour 50 of the roller 20 is offset from the contour 52 of the second roller 30, so that a completely guided rotational movement of the eccentric 12 follows. The same applies to the contours 5 54, 56, wherein the circular rotation angle range of the first roller 20 belonging to contours 46, 50, 54 is arranged in the same area, so they are arranged axially one behind the other. The same applies to the contours 48, 52, 56 belonging to the second roller 30. However, the extended rotation angle range 60 of the contours 54, 56 is arranged in a different angle of rotation range than that of the contours 50, 52, so that a different movement of the eccentric output axis 14 it follows, as will be described in more detail below.

In normal operation, ie without a desired rotation of the drive wheel 2 to the output shaft 4, the roller 20 runs in the circular contour 46 and the roller 30 in the circular contour 48. The spring 36 constantly generates a force on the two rollers 20, 30 so that they must roll on the contours 46, 48. This results in a completely defined movement of the rollers 20, 30. This means that the distance between the two rollers 20, 20 30 to Exzenterabtriebsachse 14 always remains exactly the same. Accordingly, however, a rotation of the first shaft 8 relative to the drive wheel 2 is excluded upon rotation of the drive wheel 2, since the eccentric 12 is pressed steadily outward. 5 At the opposite end of the shaft 8, a gear 64 is rotatably disposed, which meshes with a gear 66 which is rotatably mounted on the output shaft 4, respectively. Accordingly, the rotational movement of the gear 64, which is held relative to the drive wheel 2, transmitted to the gear 66. This means at the same number of teeth a ratio of 1: 1 between the drive wheel and output shaft. Any other translation can of course also be made by appropriate choice of gears. In the For use as a camshaft actuator, large ratios in the range of, for example, 80: 1 are required to provide a reasonable discrete angular range. Such translations can be realized for example by downstream differential planetary gear 5. In this respect, the device shown when used as a camshaft divider to modify accordingly.

If now a rotational movement of the output shaft 4 take place relative to the drive wheel 2, the contours 46, 48, 50, 52, 54, lo 56 are axially displaced via the actuator 58. The control for shifting takes place in such a way that the axial movement takes place in the phase in which the two rollers 20, 30 are located in the circular contoured angular regions 60 of the contours 50, 52, as a result of which the rollers 20, 30 continue to unroll. If the contours 50, 52 reached, takes place in the rotation angle range 62 a

15 displacement of the first roller 20 to the outside, since this first reaches the extension of the contour 50. As a result, the eccentric output shaft 14 is rotated in the direction of the first roller 20. The contour 52 is aligned with the contour 50 in such a way that when the roller 30 rests on the contour 52 no jamming and no lifting of the rollers 20,

20 30 by the connecting rods 16, 22, 26, 34 is formed.

During one revolution in these contours 50, 52, exactly one rotation of the eccentric 12 is produced around the first shaft 8 and thus the first stationary axis of the four-bar linkage 10. The second roller 30 has, above all, the function

25 compensate for a dead center of the first roller 20, so as to determine the direction of rotation of the eccentric 12 from the dead center. In addition, created by this second four-bar 32, a mass balance of the rotating with the drive wheel 2 parts. The translation upon rotation of the first shaft 8 to the output shaft should usually take place in small steps, so that relatively high translations must be made here. If, for example, an adjustment angle of 90 ° crank angle is required and this should be at ten revolutions of the Drive wheel 2, so be realized in ten steps, a step size of 9 ° must be realized with each rotation. Upon rotation of the camshaft at half the speed of the crankshaft, this means a rotation of 4.5 ° per revolution. Accordingly, a translation of 80: 1 would be necessary to achieve these discrete step sizes.

In the same way as the adjustment in this first direction with the contours 50, 52 and an adjustment in the opposite direction with the contours 54, 56 is possible. These are to be arranged to each other, that the eccentric is rotated in the opposite direction.

The device described for the discrete rotational angle adjustment of a drive wheel to an output shaft thus allows adjustment without having to bring in the adjustment of external energy. Only the short-term adjustment of the contours in the axial direction is required, in which no torque is applied. This is completely taken from the movement of the crankshaft itself. Correspondingly small drives with low energy consumption can be used.

It should be clear that within the scope of the main claim clear structural variants of the described embodiment are possible. For example, if necessary, the second lever can be dispensed with at sufficient angular speeds. A pressing of the roller and a rotational movement of the eccentric in a constant direction during the adjustment can be already sufficiently ensured by the centrifugal forces occurring if necessary. In addition to the role and gears that run in correspondingly shaped ring gears, which serve as contours, run off. It is also possible, the eccentric shaft as a central shaft in the drive wheel to arrange and to translate their rotation translated in the further power flow to the camshaft.

Claims

PATENT APPLICATIONS

1. Device for the discrete phase shift of a rotational angle between a drive wheel and an output shaft with

a drive wheel,

a coupling gear,

an output shaft which is driven via the coupling gear and an actuator, upon actuation of which the rotational angle of the drive wheel can be displaced to the output shaft via the coupling gear,

characterized in that

as a coupling mechanism a four-bar linkage (10) with two to the drive wheel (2) fixed axes (8, 24) and two with respect to the drive wheel (2) movable axes (14, 18), wherein the four-bar linkage (10) has an eccentric (12) the axis of rotation of which is a first one of the fixed axes (8) and whose eccentric output shaft (14) is a first of the movable axes and on a second of the movable axes (18) is disposed a roller (20) or a toothed wheel, which is optionally located in one of at least two contours (46, 50, 54) which are movable relative to the roller (20) or to the gearwheel, wherein the roller (20) or the gearwheel is pressed by means (36, 32) for pressing against the contour (46, 50, 54) is loaded.

2. Discrete phase shifting device according to claim 1,

characterized in that

a first contour (46) of the at least two contours (46, 50, 54) is a circular contour.

3. Discrete phase shifting device according to one of claims 1 or 2,

characterized in that

a second and third contour (50, 54) have rotational angle regions (60) whose diameter is greater or smaller than that of the circle of the first contour (46) and rotational angle regions (62) which have a same diameter as the first contour (46 ).

4. Discrete phase shifting device according to one of the preceding claims,

characterized in that

the first stationary axis of the four-bar linkage (10) is formed by a first shaft (8), which is rotatably mounted in the drive wheel (2) and on which the eccentric (12) is arranged.

5. Discrete phase shifting device according to one of the preceding claims,

characterized in that

on the eccentric (12) rotatably a first connecting rod (16) is mounted, at the opposite end a second shaft (18) is rotatably mounted, on which the roller (20) or the gear and a second connecting rod (22) rotatably lent are stored and which serves as a second movable axis.

6. Discrete phase shifting device according to claim 5,

characterized in that

at the opposite end of the second connecting rod (22) a third shaft (24) is rotatably mounted, whose opposite end is fixed to the drive wheel (2) and serves as a second to the drive wheel (2) fixed axis.

7. Discrete phase shifting device according to one of claims 4 to 6,

characterized in that

the first shaft (8) is centrally rotatably mounted in the drive wheel (2).

8. A device for discrete phase shift according to one of claims 4 to 6,

characterized in that

on the first shaft (8) rotatably a gear (64) is arranged, which is coupled via a reduction gear to the output shaft (4).

9. Discrete phase shifting device according to one of the preceding claims,

characterized in that

the contours (50, 46, 54) are arranged one behind the other and are axially displaceable by the actuator (58).

10. A device for discrete phase shift according to one of the preceding claims,

characterized in that

the device has a second four-bar linkage (32) whose two stationary axes (8, 24) and its first movable axis (14) correspond to the axes of the first four-bar linkage (10) and to whose second movable axis (28) a second roller (30 ) or a second gear is rotatably disposed, which or in the first contours (50, 46, 54) corresponding further contours (52, 48, 56) rotates.

11. A device for discrete phase shift according to claim 10, characterized in that the further contours (52, 48, 56) together with the first contours (50, 46, 54) via the actuator (58) are axially adjustable.

12. Discrete phase shifting device according to one of the preceding claims,

characterized in that

the means for pressing the roller (20; 30) or the gear against the contour (52, 48, 56; 50, 46, 54) are formed by a spring element (36).

13. A device for discrete phase shift according to claim 12, characterized in that

the spring element (36) biases the connecting rods (22, 26) mounted on the second stationary shaft (24) outwards.

14. A device for discrete phase shift according to claim 13, characterized in that

about the second stationary axis (24) a coil spring as a spring element (36) is arranged, the spring legs (38, 40) biased against stops (42, 44) abut against the rotatably mounted on the second stationary axis (24) connecting rods (38). 22, 26) are arranged.