WO2011116806A1

WO2011116806A1 - Gear-mechanism device

Info

Publication number: WO2011116806A1
Application number: PCT/EP2010/007518
Authority: WO
Inventors: Michael Wagenplast; Tilmann RÖMHELD
Original assignee: Daimler Ag
Priority date: 2010-03-26
Filing date: 2010-12-09
Publication date: 2011-09-29
Also published as: DE102010012914A1

Abstract

A gear-mechanism device (10) for an internal combustion engine, having a first gearwheel (12, 12') and having at least one second gearwheel (14) which can be driven by the first gearwheel, and having at least one actuating device (18, 18'), by means of which the second gearwheel (14) can be driven via the first gearwheel (12, 12') optionally in a first or a second, opposed rotational direction, wherein at least one freewheeling device (22) is provided, by means of which optionally a rotation of the second gearwheel (14) in the first rotational direction or the second rotational direction is to be made possible, and by means of which a rotation of the second gearwheel (14) in the correspondingly other rotational direction which is opposite to this rotational direction is to be prevented at least substantially.

Description

transmission device

The invention relates to a transmission device specified in the preamble of claim 1. Art.

DE 10 2008 023 206 A1 discloses a belt drive for ancillary components of an internal combustion engine, with a drive wheel, a driven wheel and a drive belt, wherein on the output gear, a clutch is provided, which is designed as a wrap spring clutch.

From DE 10 2005 047 203 A1 an internal combustion engine with arranged in a housing cylinders, a crankshaft and pistons is known, which move in the cylinders. Furthermore, a device for changing a

Compression ratio of a combustion chamber of the internal combustion engine provided. The device comprises a gear, wherein an adjusting shaft for adjusting the compression ratio is adjustable via the device and the transmission.

This transmission and other known from the mass production of cars gearbox for an internal combustion engine have further potential for improving their noise behavior.

It is therefore an object of the present invention to provide a transmission device for an internal combustion engine with a very good noise behavior.

This object is achieved by a transmission device for an internal combustion engine having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the dependent claims. Such a transmission device for an internal combustion engine comprises a first gear and at least one second gear, which is drivable by the first gear. Furthermore, the transmission device comprises at least one

Actuating device, by means of which the second gear on the first gear selectively in a first or in a second, opposite to the first direction of rotation

Direction of rotation is drivable. In other words, this means that by means of

Actuating the first gear is driven, whereby the second gear is driven. There is now provided a freewheel device, by means of which optionally a rotation of the second gear in the first or the second direction of rotation is to be made possible, and by means of which simultaneously a rotation of the second gear in the

According to other, second, this direction of rotation opposite direction of rotation is at least substantially prevented.

By the freewheel device is thus an undesirable reverse rotation, that is, a rotation of the second gear in an undesirable direction of rotation can be avoided, whereby a constant investment change of transfer members, via which the gears are coupled together for driving, is avoided. Thus, the first gear is decoupled from undesirable torques of the second gear. In addition, a game between the example, via respective gears meshing gears can be eliminated. Such transmission elements are, for example, teeth of respective toothings of the toothed wheels, chains or belts, by way of which the second tooth is drivable by the first toothed wheel.

This is accompanied by the avoidance of a noise caused by this constant change of installation, as a result of which the transmission device according to the invention has a very good noise and NVH behavior (NVH - Noise Vibration Harshness). Furthermore, the avoidance of the rotation of the second gear in the corresponding direction of rotation results in the avoidance of shocks in the respective ones

Gears, which is associated with a very low wear of the transmission device. As a result, the life expectancy of the transmission device is particularly high and what unwanted and costly repairs avoids.

It should be noted at this point that the transmission device is a transmission device with a ratio of i = 1 between the gears, So only a reversal of the direction of rotation of the first gear but no torque conversion by the transmission device takes place.

Particularly advantageous is the transmission device when used as a so-called adjusting, d. H. as a gearbox, which is predominantly, so mostly does not rotate during its life or runs synchronously at an input and an output, and possibly with changing load. Such

Adjusting gear is used in particular in internal combustion engines with variable compression ratio, for example, a shaft, in particular an eccentric shaft, is rotated to adjust the compression ratio in one or the other direction by means of the transmission device. This means that the gears rarely or possibly not perform more than a complete revolution and are often rotated with very high torques in one or the other direction, whereby always the same transmission elements, d. H. For example, the same teeth of the respective teeth, are engaged. By freewheel device at least almost no backlash of the transmission device and in particular between the respective transmission elements is created, resulting in the avoidance of

Noise due to a system change and a very low wear result. In addition, this results in a reduced risk of tooth breakage by eliminating the shocks in the teeth. In particular, the low wear and the reduced impact load cause the gear device and in particular the respective transmission elements to achieve a certain life can be dimensioned smaller, resulting in low costs and only a small

Space requirements of the transmission device result. Furthermore, this leads to a very low weight of the transmission device, resulting in a very low

Fuel consumption and low C0 ₂ emissions of the internal combustion engine can be realized.

Furthermore, no holding torque on a drive side, so on the part of the first gear, necessary. In addition, the transmission device does not have to be self-locking, which the effort of the transmission device and thus the cost and the

Requires space requirements by a further low.

Furthermore, the transmission device has the advantage that a relatively low

Drive power of the actuator due to a use of reaction forces is necessary, whereby the adjusting device is dimensioned lower both in their dimensions and in their performance. This saves weight and costs.

At this point it should be noted that the first gear, for example, with a

Drive element, in particular a drive shaft, is rotatably coupled, while the second gear, for example, with an output element, in particular a

Output shaft, rotatably coupled. Now, if the switchable freewheel device is provided in a force or torque flow between the drive element and the output element or between a fixed housing of the transmission device and the output element for both directions of rotation, the advantages already described can be realized. In each case, for example, a switchable freewheel can be provided for both directions of rotation, wherein such a freewheel is preferably designed as a wrap spring clutch with at least one wrap spring. A wrap spring clutch as freewheel has the great advantage that the wrap spring clutch has only a very small free travel until it prevents rotation of the gear in the corresponding direction of rotation. Thus, a relative rotation between the gears is avoided particularly efficiently, which at least virtually avoids a system change and a resulting noise.

The freewheel device is, for example, at least on the one hand rotatably supported on the housing or on the first gear or the drive element or supportable via a switching device, while on the other hand rotatably supported on the second gear or the driven element or can be supported via a switching device. As a result, the relative rotation between the two gears is prevented. An undesired rotation of the first gear is prevented, for example by the adjusting device, which preferably has an electric motor, by means of which the first gear is optionally driven via the drive shaft.

As already indicated, the freewheel device is advantageously designed as a switchable freewheel device, which between a rotation in the first

Allowing rotation direction and the rotation in the second direction preventing state and a rotation in the second direction permitting and the rotation in the first direction of rotation preventing state is reversible. In all respects, the freewheel device eliminates play of the transmission device, in particular between the gears and at least one transmission member, for example between gears of the gears and a chain or belt or between respective gears of the gears which engage with each other, thereby preventing vibrations, actuation of the

Transmission device supported by means of the adjusting device by torque components in the desired direction of rotation and a load of transmission elements such as teeth of the respective gears of the gears, chains, etc. are significantly reduced. In addition, the first gear is decoupled from return torques, wherein, for example, the second gear is supported by the freewheel device on a housing of the transmission device.

To avoid the unwanted rotation of the second gear in a direction of rotation there are several ways to avoid such rotation in a direction of rotation by means of the wrap spring clutch. The wrap spring clutch comprises, for example, a wrap spring with two spring ends, wherein one of the spring ends frictionally rests against a cylinder surface rotatably coupled to the second gear. The other of the spring ends is non-rotatably coupled to a relatively rotatable housing relative to the second gear of the transmission device and / or is frictionally engaged on a non-rotatably coupled to the housing cylinder surface. If the other end of the spring is non-rotatably coupled to the housing and is frictionally engaged with the cylinder surface that is non-rotatably coupled to the housing, this has the advantage that a clamping of the spring end is relieved and a position of one spring end is fixed. Depending on the direction of rotation of the rotatably coupled to the second gear cylindrical surface and thus depending on

Direction of rotation of the second gear, the wrap spring can build a holding force according to the rope friction formula F ₂ = F _l - β ^{μ α} , where a is the wrap angle of

Cylinder surface through the wrap is or not. If the second toothed wheel rotates in a direction of rotation in which the wrap spring can not build up a holding force, only a slight frictional torque is produced by a contact force of the corresponding spring end.

The spring end which frictionally rests against the cylinder surface rotatably coupled to the second gear, is coupled, for example, with a switching device by means of which this spring end of the cylinder surface can be lifted, which therefore no longer the spring end upon actuation of the switching device frictionally engages the cylindrical surface. This allows a rotation of the cylindrical surface and thus of the second gear in the direction of rotation, in which the wrap spring at frictionally fitting to the cylinder surface spring ends normally the

Build up holding force and prevent rotation in the direction of rotation. This means that upon rotation of the second gear in a locked direction of rotation and unactuated switching device coupled to the second gear cylinder surface is rotatably coupled via the wrap of the wrap spring with the rotatably coupled to the housing cylindrical surface, thereby rotating the second gear in this unwanted, blocking direction of rotation is prevented. In this case, the wrap spring applies with its spring coils to both cylindrical surfaces. Due to the friction between the spring coils of the wrap spring and the corresponding cylindrical surfaces, which adds up with the number of spring coils, thus with the second gear rotatably coupled cylindrical surface with the with the

Housing rotatably coupled cylindrical surface rotatably coupled, whereby rotation of the second gear is prevented in the undesired direction of rotation. When operated switching device, the second gear can be rotated in this undesired direction of rotation, since the corresponding spring end and the spring coils of the

Cylinder surface lifts off or lifting, preventing or releasing a rotation of the second gear in the opposite direction of this undesirable rotation

Direction of rotation is to provide a second wrap spring clutch, for which the same applies to the first Schlingefederkupplung executed analog.

Alternatively, there is the possibility, with unactuated switching device not abutting the cylindrical surfaces spring ends or not fitting to a corresponding cylindrical surface spring end of the wrap by pressing the

Spend switching device in frictional engagement of the spring ends and the spring end to the cylinder surfaces or on the cylinder surface. However, this would result in a small amount of travel of the wrap spring clutch, although a small amount of force build-up to prevent rotation of the second gear in the undesirable direction of rotation.

This means that the blocking effect of the wrap spring clutch is switched off advantageously by actuating the switching device. This is advantageous insofar as thereby always one of the two Schlingfederkupplungen (a Schlingfederkupplungen per direction of rotation of the second gear) is active, which ensures a high reliability of the transmission device.

Furthermore, there is the possibility that one of the cylinder surfaces is not rotatably coupled to the housing but rotatably coupled to the first gear, said corresponding to this cylindrical surface spring end of the wrap spring

Schlingfederkupplung continues to interact with this cylindrical surface or

can interact. In this case, a rotation of the second gear in the undesired direction of rotation is not represented by supporting on the housing but by being supported on the first gear, which for example via the

Control device can be held against rotation. This prevention of rotation of the second gear in the undesired direction of rotation can in turn be made possible by pressing the switching device, so for example, the spring end of the rotatably coupled to the second gear cylindrical surface and / or the spring end of the rotatably coupled to the first gear cylinder surface lifts.

In any respect, such a wrap spring clutch basically works when both spring ends abut frictionally on the respective, otherwise mutually rotatable cylinder surfaces, since the cable friction effect acts on both cylindrical surfaces. One of the spring ends is advantageous then rotatably fix when the

Cylinder surface should be omitted or if a rotational position when lifting the

Spring element of the corresponding cylindrical surface should be precisely defined or must.

To depict a particularly cost-effective freewheel device with a small space requirement, the wrap spring clutch comprises at least two wrap spring elements, d. H. Windings or winding parts of a wrap, each with a first

Spring end and a second spring end, wherein each of the first spring end is rotatably coupled to the second gear, and wherein in each case the second spring end with the housing of the transmission device or with the first gear rotatably coupled. The possibility of non-rotatably coupling the respective first spring end to the second gear as a result of the cable friction effect, for example via the output element, thereby creates the possibility of preventing unwanted rotation in the first or second rotational direction, depending on which direction of rotation the corresponding one is Schlingfederelement locks. So the rotation is avoided in just this direction of rotation, while the rotation in the other direction of rotation for actuating the transmission device, for example, to set a compression ratio of the

Internal combustion engine, is made possible by the freewheel device. It is preferably also provided that at least one spring end of each

Schlingfederelements is coupled to a switching device which lifts the spring end of the corresponding cylindrical surface, whereby the rotation in the otherwise locked and undesired direction of rotation is possible.

Further advantages, features and details of the invention will become apparent from the following description of two preferred embodiments and from the drawings. The features mentioned above in the description and

Feature combinations as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures are not only in the respectively indicated combination but also in others

Combinations or alone, without departing from the scope of the invention.

The drawings show in:

Fig. 1 is a schematic view of an adjusting for a

Internal combustion engine having a first gear and a second gear, which are mutually engaged via respective gears, wherein a freewheel device is provided, by means of which an undesirable relative rotation of the gears is mutually avoidable; and

Fig. 2 is a schematic view of another embodiment of a

Variable transmission according to FIG. 1.

Fig. 1 shows an adjusting mechanism 10 for an internal combustion engine, by means of which, for example, an eccentric shaft of the internal combustion engine is adjustable in order to set a compression ratio of the internal combustion engine. For this purpose, the adjusting mechanism 10 comprises a first gearwheel 12 which is coupled in a rotationally fixed manner to a drive shaft 15. Furthermore, the adjusting mechanism 10 includes a second gear 14, which is non-rotatably coupled to an output shaft 16. The Output shaft 16 is connected via the gear 14 and via the gear 12 and the

Drive shaft 15 can be driven by means of an electric motor 18, wherein the output shaft 16 in accordance with a directional arrow 20 in a first or a second, this

opposite direction of rotation can be driven.

If the output shaft 16 is to be rotated, for example, in the first direction of rotation, then it is desirable to avoid a rotation of the output shaft 6 in the second direction of rotation, which is accompanied by an avoidance of a change in the gear teeth of the gears 12 and 14. Such a system change would cause noise and excessive strain on the gears. Such unwanted rotation in the second direction of rotation occurs, for example, by vibrations,

Gegenmomente or the like. At the same time, however, the rotation of the output shaft 16 should be possible in the first direction of rotation, since this rotation causes an adjustment of the compression ratio of the internal combustion engine in this direction of rotation.

The same applies to a desired rotation of the output shaft 16 in the second

Direction of rotation and a desired in this case avoiding the rotation of the output shaft 16 in the first direction of rotation.

To avoid the rotation of the output shaft 16 in the undesired direction of rotation while allowing the rotation of the output shaft 16 in the desired

Direction of rotation, the adjusting gear 10 comprises a freewheel device 22 with two trained as Schlingfederkupplungen 24 and 26 and by means of a respective

Actuator 28 and 30 switchable freewheels.

The wrap spring clutch 24 serves the purpose of rotating the output shaft 16 and thus of the gear 14 in the first direction of rotation when unconfirmed

Actuator 28 to avoid, but to allow rotation of the output shaft 16 in the second direction of rotation. The wrap spring clutch 26 serves the purpose of preventing rotation of the output shaft 16 in the second direction of rotation when the actuating device 30 is not actuated, and to allow the output shaft 16 to be rotated in the first direction of rotation.

For this purpose, the wrap spring clutches 24 and 26 respective wrap springs 32 and 34, which are coupled on the one hand via a coupling point 36 and 38 rotatably connected to a housing of the adjusting 10 and to corresponding cylindrical surfaces 40 and 42 abut frictionally. On the other hand, the wrap springs 32 and 34 are frictionally engaged on corresponding cylindrical surfaces 44 and 46, wherein the

Cylindrical surfaces 40 and 42 are rotatably coupled to the housing of the adjusting 10, while the cylindrical surfaces 44 and 46 rotatably coupled to the output shaft 16 and thus to the second gear 14. If the gear 14 in the first

Turning the direction of rotation, this would be made possible by the wrap spring clutch 26 and avoided by the wrap spring clutch 24, however. In order to still allow rotation of the gear 14 in the first direction of rotation, the actuator 28 is actuated, whereby the wrap spring 32 lifts from the cylindrical surface 42. As a result, the wrap spring clutch 24 no longer avoids turning the gear 14 in the first direction of rotation, whereupon the gear 14 can be rotated in the direction of rotation. However, the wrap spring clutch 26 still avoids further rotation in the second direction of rotation.

Is a rotation of the gear 14 in the second direction desired in the first direction of rotation undesirable, however, the actuation of the actuator 28 is released and the actuator 30 is actuated, whereby the wrap spring 34 lifts from the cylindrical surface 46 and the wrap spring clutch 26, a rotation of the gear 14th in the second direction of rotation can not prevent. Also, the wrap spring clutch 24 allows rotation of the gear 14 in the second direction of rotation, however, prevents rotation of the gear 14 in the first direction of rotation, whereby the desired functionality of the variator 10 is provided. On the shaft 16 adjacent torsional vibrations can thus not each impact on the gear 12.

The positions of the spring ends of the wrap springs 32 and 34 on the part of

Actuators 28 and 30 result from the length of the wrap springs 32 and 34, respectively.

FIG. 2 shows a further embodiment of the adjusting mechanism 10, wherein the adjusting mechanism according to FIG. 2 now comprises a first electric motor 18 and a second electric motor 18 'and a planetary gear 48.

About the electric motor 18 'is a drive shaft 15' and above a with the

Drive shaft 15 'coupled gear 12' drivable, via the electric motor, the Drive shaft 15 and about the rotatably coupled to the drive shaft 15

Gear 12 is driven. About the gear 12 'is in turn with a

Planet carrier 50 connected gear 52 drivable on which planet gears 54 are rotatably mounted. Combing the gear 12 'and the gear 52 via respective teeth, as well as the planet gears 54 mesh with a ring gear 56 of the planetary gear 48 via respective teeth. The ring gear 56 is in turn connected to the output shaft designed as a hollow shaft 16, with which the gear 14 is rotatably connected.

Also, the adjusting 10 includes a freewheel device 22 with a as

Schlingfederkupplung 24 trained freewheel, which comprises an inner wrap spring 32 and an outer wrap spring 34, which to avoid unwanted rotation of the output shaft 16 and thus of the gear 14 due to

Seilreibseffekts rotatably coupled to the output shaft 16, whereby the output shaft 16 rotatably coupled to an undesirable rotation in the undesirable direction of rotation with the drive shaft 15 and can be coupled. By pressing the respective actuator 28 and 30, the respective blocking effect of the respective wrap springs 32 and 34 can be canceled, whereby rotation in the corresponding and otherwise locked by the respective wrap springs 32 and 34 rotational direction is possible. In the adjusting 10 of FIG. 2, the gears 12 and 14 on the

Freewheel device 22 clamped together.

The adjusting mechanism 10 according to FIGS. 1 and 2 thus provide almost no play

Adjustment 10, in which system changes are avoided, resulting in low wear and a very good noise behavior of

Adjusting gear 10 is associated.

Claims

claims

A transmission device (10) for an internal combustion engine, comprising a first gearwheel (12, 12 ') and at least one second gearwheel (14) which is drivable by the first gearwheel and at least one adjusting device (18, 18') which is the second gear (14) via the first gear (12, 12 ') selectively driven in a first or a second, opposite direction of rotation, characterized in that

at least one freewheel device (22) is provided, by means of which a rotation of the second gear (14) in the first direction of rotation or the second direction of rotation is to be enabled, and by means of which a rotation of the second gear (14) in the corresponding other, this direction of rotation opposite direction of rotation is at least substantially prevented.

2. Transmission device (10) according to claim 1,

characterized in that

the freewheel device (22) is designed as a switchable freewheel device (22).

3. transmission device (10) according to any one of claims 1 or 2,

characterized in that

the freewheel device (22) comprises at least two respectively switchable freewheels (24, 26).

4. Transmission device (10) according to one of the preceding claims,

characterized in that

the freewheel device (22) comprises at least one freewheel (24, 26), which is designed essentially as a wrap spring clutch (24, 26).

5. transmission device (10) according to claim 4,

characterized in that

the wrap spring clutch (24, 26) comprises at least two wrap spring elements each having a first spring end and a second spring end, wherein in each case the first spring end with the second gear (14) is rotatably coupled and in each case the second spring end with a housing of the transmission device (10) or with the first gear (12) rotatably coupled.