Actuation assembly for a transmission

Abstract

The invention relates to an actuation assembly for a transmission. The actuation assembly has at least one controller cylinder (10) and a pivotally mounted pawl (14). The controller cylinder (10) is designed to push the pawl (14) out of engagement with a shift element part (16) by being rotated in order to actuate a shift element of the transmission. The actuation assembly has at least one means for reducing frictional force when actuating the shift element. The invention additionally relates to a vehicle.

Description

[0001] ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 Actuating arrangement for a transmission The present invention relates to an actuating arrangement for a transmission. The invention also relates to a vehicle. Many transmissions are shifted using shift drums. By rotating the shift drum, different shift elements are shifted centrally, for example, to provide a desired gear. For example, depending on the rotational position of the shift drum, different rotating elements of planetary gear sets of the transmission are connected to one another in a rotationally fixed manner. The rotary movement can release an engagement of a pawl with a shift element part. Due to the applied drive torque, however, a high torque can arise, which is supported on the engagement of the pawl. As a result, a high actuating torque can be required to rotate the shift drum and thus change gears in the transmission upon release.Depending on the selected gear, the actuating torque may increase even further. This actuating torque can be unpleasant for the operator and lead to incorrect operation or generally hinder gear changes. If the shift drum is rotated by a servo, this can be large and expensive to provide sufficient power. The servo must be designed for the highest load to enable reliable shifting. A first aspect of the invention relates to an actuating arrangement for a transmission. A transmission can be a device that transmits drive torque from an input to an output. The transmission can, for example, transmit the drive torque from an engine to a tire of a vehicle. The transmission can be designed to provide different switchable gears for torque transmission.For this purpose, the transmission can, for example, have respective spur gear stages and, alternatively or additionally, respective planetary gear sets. The transmission can, for example, be designed as a bicycle transmission. The transmission can accordingly be designed, for example, as a hub gear or bottom bracket gear. A gear can, for example, provide a fixed ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 ratio between an input and an output of the transmission. The actuating arrangement has a shift drum. The shift drum can be a component whose actuation causes a gear change of the transmission. For example, the shift drum can be rotated in order to actuate different shifting elements. By means of the shift drum, the gears of the transmission can, for example, be shifted centrally in series with a single actuation. The actuating arrangement has a pivotably mounted pawl.The pawl can, for example, be pivotally mounted on a housing of the transmission, for example by means of a bolt. The actuating arrangement can also have a plurality of pawls, which can be mounted together on the bolt or separately. The shift drum is designed to rotate to press the pawl out of engagement with a shift element part in order to actuate a shift element of the transmission. This allows a gear change to occur. In certain positions of the shift drum, the pawl can engage with the shift element part. For this purpose, the pawl can be preloaded with a spring, for example, in the direction of the shift element part. The shift drum can be designed to rotate to press a pawl out of engagement with a shift element part in a gear-dependent manner in order to actuate the shift element of the transmission. Gear-dependent can also refer to a current gear, a gear change, or even a gear that is being engaged.A shifting element of the transmission can, for example, connect two elements of the transmission, such as rotating elements of a planetary gear set or shafts of a spur gear stage, to one another in a rotationally fixed manner. For example, by actuating a shifting element, the shifting element can be adjusted between an open and closed state. In the open state, the shifting element cannot transmit any torque, for example. In the closed state, the shifting element can, for example, transmit torque. A shifting element can, for example, be designed as a positive or frictional clutch ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31. A shifting element can function as a brake, by means of which a moving part of the transmission can be locked. The shifting element part can, for example, be designed as one half of a clutch of the shifting element.The shift element part can, for example, rotate at least in certain gears of the transmission when a drive torque is applied. The shift element part can, for example, be supported on the pawl at least in certain gears and thus be prevented from rotating. The pawl can be designed as a movable part which is pivoted by the action of the shift drum. For this purpose, one end of the pawl can be in contact with the shift drum. Another end of the pawl can be designed to engage with the shift element part. For example, in one gear the pawl can engage with an external toothing of the shift element part, from which the pawl can be pressed by the shift drum to change to another gear. The shift element part has, for example, a toothing on its outer circumference for engagement with the pawl. The shift element part can, for example, be designed as a brake ring.The shift drum has, for example, a drum body. The drum body can, for example, be made of a metallic material. The drum body can, for example, have a cylindrical basic shape. The shift drum can have respective actuating regions for pressing the pawl out of engagement with the shift element part. An actuating region can, for example, protrude from a circumferentially adjacent region of the drum body. An actuating region can, for example, be formed by one side of a cam of the drum body. By rotating the shift drum, an actuating region can, for example, press against the pawl and thus release it from engagement with the shift element part. Depending on the angular position of the shift drum, the pawl can then be pressed out of engagement with the shift element part. Certain rotational angular positions of the shift drum can each correspond to a gear of the transmission.For example, in both a first and a second gear, the engagement of the pawl with the shift element part can be canceled. In further gears, for example a third gear, the pawl can, however, be engaged with the shift element part. The actuating arrangement has at least one means for reducing frictional force when actuating the shift element. The means can relate to a structural design of the actuating arrangement. The means can be a mechanical design of the actuating arrangement. A frictional force can be caused by a relative movement of two parts of the actuating arrangement during the rotation of the shift drum or a gear change or actuation of the shift element and can counteract an actuating force.For example, slipping of the shift drum at the end of the pawl facing the shift drum can cause such an opposing frictional force. This frictional force can be reduced by the means for reducing the frictional force compared to actuating arrangements without such a means. As a result, the actuating force and also the actuating torque for actuating the shift element can be particularly low. The means for reducing the frictional force can be a measure for reducing the friction coefficient between two parts of the actuating arrangement that are movable relative to one another. The shift drum can be designed to actuate a plurality of pawls. The pawls can be arranged axially next to one another. For example, an axial region of the shift drums can be provided for each pawl, each with actuating regions assigned to the corresponding pawl. As a result, a plurality of shift elements can be actuated for a gear change.For example, the transmission can have two shift elements, each with an associated pawl. The pawls can thus be brought out of engagement with an associated shift element part by the shift drum, depending on the gear. In one embodiment of the actuating arrangement, the means for reducing frictional force is at least one bearing of a movable part of the actuating arrangement by means of a rolling bearing. This movable part can be mounted on a stationary or other movable part of the actuating arrangement using the rolling bearing. Movable parts of the actuating arrangement can be, for example, the pawl, the shift drum, and the bolt. ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 Immobile parts of the actuating arrangement can be, for example, the housing and the bolt. A rolling bearing is particularly suitable as a means for reducing frictional force, since actuating speeds can be low orthe moving parts move at low speed. The friction in rolling bearings is relatively independent of speed compared to plain bearings. In addition, a rolling bearing has low friction even at low relative speeds. A rolling bearing can have an inner ring, an outer ring and rolling elements located between them, which roll when the outer ring and inner ring move relative to each other. For example, the rolling elements can be designed as balls or cylinders. The rolling bearing can be designed, for example, as a single-row or double-row ball bearing. The rolling bearing can be designed, for example, as a cylindrical roller bearing or needle bearing. In addition, a cage can be provided for the rolling elements. The actuating arrangement can have several rolling bearings as a means of reducing frictional force.In one embodiment of the actuating arrangement, it is provided that the shift drum is mounted by means of a rolling bearing as a means for reducing frictional force. This can directly reduce the actuating torque for rotating the shift drum for all gears and angular positions. For example, the shift drum can be rotatably mounted on the housing of the transmission by means of the rolling bearing. The housing can be part of the actuating arrangement. The housing can, for example, have a cover and a housing body and form an interior space. The actuating arrangement and respective shifting elements can be accommodated in the interior of the housing. The shift drum can, for example, be mounted at each axial end with a rolling bearing. In one embodiment of the actuating arrangement, it is provided that the pawl is mounted by means of a rolling bearing as a means for reducing frictional force. This can make the torque for rotating the pawl particularly small.This also allows a spring for preloading the pawl in the direction of the switching element part to be dimensioned particularly small. For example, the pawl can be rotatably mounted on the bolt by means of the rolling bearing. The bolt can, for example, be fixed to the housing or rotatably mounted. The bolt can be part of the actuating arrangement. The rolling bearing can be attached directly to the pawl, for example with an inner ring or outer ring of the rolling bearing. In one embodiment of the actuating arrangement, it is provided that the pawl is mounted on a bolt and the bolt is rotatably mounted by means of a rolling bearing as a means for reducing frictional force. For example, the bolt can be rotatably mounted on the housing by means of the rolling bearing. The pawl can, for example, be mounted on the bolt in a rotationally fixed manner.Such a design can be cost-effective if only one pawl is mounted on the bolt in a rotationally fixed manner. The bolt can be part of the actuating arrangement. In one embodiment of the actuating arrangement, it is provided that the pawl is rotatably mounted on the bolt. This can further reduce actuating forces. In addition, several pawls can be attached to the bolt and pivot independently of one another. For example, at most one of this plurality of pawls is connected to the bolt in a rotationally fixed manner. For example, the other pawls can be rotatably mounted on the bolt by means of a rolling bearing, as already described. In one embodiment of the actuating arrangement, it is provided that the pawl is mounted on the bolt in a rotationally fixed manner. If at least two pawls are provided, one pawl can be mounted on the bolt in a rotationally fixed manner and one pawl can be rotatably mounted.For example, the pawl can be connected to the pawl in a rotationally fixed manner by a press fit or by means of a locking pin. The rotationally fixed bearing can result in a cost-effective and simple design with only one pawl, which is mounted on a single bolt. In one embodiment of the actuating arrangement, the pawl has a rotatable roller as a means of reducing frictional force. The rotatable roller can roll on an actuating region of the shift drum for pressing the pawl out of engagement with the shift element part, for example when the shift drum is rotated. As a result, friction between the shift drum and the pawl can be particularly low, which also means that actuating torques can be particularly low. The roller can, for example, be arranged on an end region of the pawl that faces the shift drum.An opposite region of the pawl can form the engagement region of the pawl with the shift element part. The roller can be arranged in contact with the shift drum, for example with the outer circumferential surface of the drum body. The roller can be mounted, for example, on a rolling bearing. This can further reduce friction and thus the actuating force. The roller can also be formed by the rolling bearing. For example, an outer ring of the rolling bearing forming the roller then rolls on the shift drum. This requires particularly few parts. In one embodiment of the actuating arrangement, it is provided that the means for reducing frictional force is at least one friction surface material pairing between two surfaces of a first part and a second part of the actuating arrangement, which surfaces are at least partially in contact with one another during actuation of the shift element and are movable relative to one another.A friction surface material pairing can correspond to the material of a first surface and a second surface, wherein the surfaces can slide against each other, causing a frictional force. The first surface can be a surface of the first part and the second surface a surface of the second part. The means can accordingly relate to the material selection of these surfaces. The surface can, for example, be formed by a coating on the part. The surface can, for example, be formed by a material of the part from which its body is formed. In addition to its selection, this material can also be modified by a surface treatment as a means of reducing the frictional force, for example, surface hardening.A pair of surfaces that are in contact with each other during actuation of the shifting element and that are movable relative to each other can be formed, for example, by the shift drum as the first part and the pawl as the second part. A pair of surfaces that are in contact with each other during actuation of the shifting element and that are movable relative to each other can be formed, for example, by the shift drum as the first part and the housing as the second part. A pair of surfaces that are in contact with each other during actuation of the shifting element and that are movable relative to each other can be formed, for example, by the housing as the first part and the pawl as the second part. A pair of surfaces that are in contact with each other during actuation of the shifting element and that are movable relative to each other can be formed, for example, by the bolt as the first part and the pawl as the second part.A pair of surfaces that come into contact and are movable relative to one another during actuation of the shift element can be formed, for example, by the bolt as the first part and the housing as the second part. The corresponding material pairings can be selected to minimize frictional forces and treated alternatively or additionally. For example, instead of two steel materials, a steel material with an aluminum material can be provided as the friction material pairing. For example, an aluminum material can be hard-anodized to minimize friction. In terms of friction, a hard-anodized aluminum shift drum has an advantage over a non-anodized aluminum shift drum, for example, if there is sliding friction contact between the shift drum and the pawl.In one embodiment of the actuating arrangement, it is provided that the friction surface material pairing corresponds to a material of the first part and a material of the second part of the actuating arrangement, wherein during operation of the transmission no drive force transmitted by the transmission is introduced into at least the first part. The loads on the first part are therefore low, so that, for example, a softer material can be selected for it than for a second part, into which a drive force transmitted by the transmission is introduced during operation of the transmission. The drive force can, for example, correspond to a torque transmitted by the engine. For example, only a small force is supported on the shift drum. In contrast, the shift element part and the pawl can be subjected to the drive force when the pawl is engaged with the shift element part.Accordingly, such a part should not be made of a soft material. A material forming the first part can, for example, be a different material than the material forming the second part. ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 In one embodiment of the actuating arrangement, it is provided that one of the two parts has a base material and a surface material for the friction surface material pairing. The surface material can form at least a first of the surfaces that come into contact during actuation of the shift element and are movable relative to one another. The surface material thus specifies the coefficient of friction. The base material, on the other hand, can be irrelevant for the coefficient of friction when sliding against one another.Compared to the base material, the surface material can have a lower coefficient of friction with a second of the surfaces that come into contact and are movable relative to one another during actuation of the switching element. This can result in particularly low friction. To save costs, for example, only a portion of an outer surface of the part of the actuating arrangement can be formed by the surface material, while the remaining outer surface can be formed by the base material. The remaining outer surface cannot, for example, come into contact with other surfaces that are movable relative to it during actuation of respective switching elements. In one embodiment of the actuating arrangement, it is provided that the shift drum is the part with the base material and the surface material. In this case, the surface material can, for example, form a contact surface between the shift drum and the blade and, alternatively or additionally, the housing.As a result, the torque required to rotate the shift drum can be particularly small. For example, the shift drum can have a base material and a surface material. The surface material and the base material are different from one another. The surface material can form at least one actuating region. Compared to the base material, the surface material can have a lower coefficient of friction with a material of the pawl that contacts the shift drum. As a result, the actuating force required to disengage the pawl can be lowered due to reduced friction between the pawl and shift drum. The surface material can differ from the base material, for example, in terms of a material, a crystal structure, and alternatively or additionally, a doping.For example, the surface material can be formed by a coating or by a surface treatment of the base material. By combining the surface material and the base material, a cost-effective, lightweight and, alternatively or additionally, robust material can be selected as the base material, regardless of its friction with the pawl, without resulting in an increased actuating force. For example, it can be provided that a partial area of ​​the surface of the shift drum is formed by the base material. For example, an end face of the shift drum can be formed by the base material. Alternatively or additionally, an area of ​​the surface of the drum body, such as an area of ​​the circumferential surface which does not form an actuating area, can also be formed by the base material.For example, coating material can be saved or surface treatment can be limited to small areas. In one embodiment of the actuating arrangement, it is provided that the actuating arrangement has a housing of the transmission. The housing can, for example, correspond to the housing described above. The housing can, for example, be a cast component or steel component. The housing can be the part with the base material and the surface material. The surface material can, for example, form a bearing for the bolt and, alternatively or additionally, the shift drum. In one embodiment of the actuating arrangement, it is provided that the actuating arrangement has the shift element part. The actuating arrangement can also have the entire shift element. The actuating arrangement can also have the transmission. The transmission and the shift element can also be different components of the actuating arrangement.The shifting element can be part of the transmission. A second aspect relates to a vehicle with a transmission having the actuating arrangement according to the first aspect. Respective further features, embodiments, and advantages can be found in the descriptions of the first aspect. Conversely, features, embodiments, and advantages of the second aspect also represent features, embodiments, and advantages of the first aspect. A shifting element of the transmission can be actuated by means of the actuating arrangement. The vehicle can be designed as a bicycle, for example as an e-bike, pedelec, velomobile, cargo bike, or the like. The transmission can be designed as a bicycle transmission. For example, the transmission can be designed as a hub gear or bottom bracket gear. The shifting element can thus be actuated with particularly little force. This facilitates use.Especially on bicycles, shifting elements are usually operated manually, for example by rotating the shift drum using a shift lever via a shift cable. The shift lever can therefore be small and the operating force still low. Even with servo shifting, the servo can be small and cost-effective. Fig. 1 schematically illustrates an actuating arrangement for a transmission with a shift drum. Fig. 1 illustrates an actuating arrangement for a bicycle transmission. The actuating arrangement has a shift drum 10 with a roller body, a pawl 14 and a shift element part 16 designed as a brake ring. The pawl 14 is pivotally mounted on a bolt 18 and preloaded by a spring element 20 into engagement with the shift element part 16.An end region 22 of the pawl 14 facing away from the shift drum 10 engages with a toothing of the shift element part 16 when the shift drum 10 does not push the pawl 14 away from the shift element part 16 and thus out of engagement. This actuation of the pawl 14 occurs gear-dependently by rotation of the shift drum 10 about its longitudinal axis, which corresponds to a central axis of the drum body and extends into the image plane. The drum body has four cam-like elevations 28 on its outer circumferential surface. An end region 24 opposite the end region 22 and facing the shift drum 10 slides along the outer circumferential surface when the shift drum 10 rotates. At ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 When the cam-like elevation is reached, the pawl 14 is pressed out of engagement with the switching element part 16 by a flank 26 during an exemplary counterclockwise rotation.The cam-like elevations 28 and the flanks 26 are all identically shaped in the actuating arrangement shown in Fig. 1. The shift drum 10 is thus designed symmetrically. In order to change gears, the shift drum 10 must overcome a frictional force between the end region 22 of the pawl 14 and the contacted tooth flank of the shift element part 16 by releasing the engagement of the pawl 14 with the shift element part 16. This results in a corresponding switching torque for rotating the shift drum 10. This also results in a frictional force which keeps the pawl 14 in engagement with the shift element part 16. This frictional force must be overcome by the switching torque for the gear change. In addition, the switching torque must overcome all other frictional forces between two parts which are in contact with one another and which are moved relative to one another by the actuation.The actuating arrangement provides several means for reducing frictional force when the shifting element is actuated by rotating the shift drum 10. The shift drum 10 is rotatably mounted on a transmission housing by means of a rolling bearing (not shown). The end region 24 of the pawl 14 is formed by an additional roller 52, which in the example shown is designed as a rolling bearing and is mounted on a pin of the pawl 14. The pawl 14 rolls along the outer circumferential surface of the roller body of the shift drum 10 with the roller 52. For this purpose, an outer ring of the rolling bearing forming the roller 52 is in contact with the outer circumferential surface of the roller body of the shift drum 10. As a result, friction between the shift drum 10 and the pawl 14 is lower than in an actuating arrangement without such a roller 52. This reduces the switching torque for changing gears or the actuating torque for rotating the shift drum 10.The pawl 14 is mounted on the bolt 18 by means of a rolling bearing. The bolt 18 is mounted on the transmission housing by means of a rolling bearing. ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 Furthermore, in one embodiment, the aluminum shift drum 10 is hard anodized in the area in which the roller 52 rolls on its rolling elements. In an alternative embodiment, the shift drum is made of steel. The outer ring of the roller 52 is made of steel. The shift drum 10 forms a first surface as a first part of the actuating arrangement. The outer ring of the roller 52 of the pawl 14 forms a second surface as a second part of the actuating arrangement. These two surfaces are in contact with one another during actuation of the shifting element and move relative to one another. Due to the means for reducing the frictional force, the friction during actuation of the shifting element and thus the actuating force are particularly low.In a further embodiment, no roller 52 is provided. Instead, the end region 24 of the pawl 13 is in direct sliding friction contact with the shift drum 10. In this embodiment, the hard anodizing of the aluminum shift drum 10 results in a particularly significantly reduced friction between the shift drum 10 and the pawl 14 compared to a shift drum 10 without such a hard anodizing.

[0002] ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 Reference number 10 Shift drum 14 Pawl 16 Shift element part 18 Bolt 20 Spring element 22 End area 24 End area 26 Flank 28 Elevations 52 Roller

Claims

ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 Patent claims 1. An actuating arrangement for a transmission, wherein the actuating arrangement has at least one shift drum (10) and a pivotably mounted pawl (14), wherein the shift drum (10) is designed to press the pawl (14) out of engagement with a shift element part (16) by rotation in order to actuate a shift element of the transmission, wherein the actuating arrangement has at least one means for reducing frictional force when actuating the shift element.

2. An actuating arrangement according to claim 1, characterized in that the means for reducing frictional force is at least one bearing of a movable part of the actuating arrangement by means of a rolling bearing.

3. An actuating arrangement according to claim 2, characterized in that the shift drum (10) is mounted by means of a rolling bearing as a means for reducing frictional force. 4.Actuating arrangement according to claim 1 or 3, characterized in that the pawl (14) is mounted by means of a rolling bearing as a means for reducing frictional force.

5. Actuating arrangement according to one of the preceding claims 2 to 4, characterized in that the pawl (14) is mounted on a bolt (18) and the bolt (18) is rotatably mounted by means of a rolling bearing as a means for reducing frictional force.

6. Actuating arrangement according to claim 5, characterized in that the pawl (14) is rotatably mounted on the bolt (18).

7. Actuating arrangement according to claim 5, characterized in that the pawl (14) is mounted on the bolt (18) in a rotationally fixed manner. ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 8. Actuating arrangement according to one of the preceding claims, characterized in that the pawl (14) has a rotatable roller (52) as a means for reducing frictional force, which rolls on an actuating region of the shift drum (10) for pressing the pawl (14) out of engagement with the shift element part (16).

9. Actuating arrangement according to one of the preceding claims, characterized in that the means for reducing frictional force is at least one friction surface material pairing between two surfaces of a first part and a second part of the actuating arrangement, which surfaces are at least partially in contact with one another during actuation of the shift element and are movable relative to one another. 10.Actuating arrangement according to claim 9, characterized in that the friction surface material pairing corresponds to a material of the first part and a material of the second part of the actuating arrangement, wherein during operation of the transmission, at least the first part does not introduce any drive force transmitted by the transmission.

11. Actuating arrangement according to one of the preceding claims 9 or 10, characterized in that for the friction surface material pairing, one of the two parts has a base material and a surface material, wherein the surface material forms at least a first of the surfaces that are contacted during actuation of the switching element and are movable relative to one another, and wherein the surface material has a lower coefficient of friction with a second of the surfaces that are contacted during actuation of the switching element and are movable relative to one another compared to the base material.Actuating arrangement according to one of the preceding claims 9 to 11, characterized in that the switching drum (10) is the part with the base material and the surface material. ZF Friedrichshafen AG File 215274 Friedrichshafen 2023-01-31 13. Actuating arrangement according to one of the preceding claims 9 to 12, characterized in that the actuating arrangement comprises a housing of the transmission, and the housing is the part with the base material and the surface material.

14. Actuating arrangement according to one of the preceding claims, characterized in that the actuating arrangement comprises the shifting element part (16).

15. Vehicle with a transmission having the actuating arrangement according to one of the preceding claims, wherein a shifting element of the transmission can be actuated by means of the actuating arrangement.

Images