Transmission device and method

Abstract

Transmission device (1) with a housing (2) and at least two transmission components (3, 4), wherein a first (3) of the transmission components (3) comprises a transmission shaft (9) and a rotor (6) and is rotatably arranged on the housing (2), wherein a fluid chamber (7) is provided on the housing (2), which comprises a magnetorheological coupling gap (8) with a gap width (18) between the rotor (6) of the first transmission component (3) and a second transmission component (4) of the transmission components (3, 4), wherein the fluid chamber (7) is provided with a magnetorheological fluid (20) such that the coupling gap (8) is at least partially filled with the magnetorheological fluid (20), and wherein at least one magnetic field source (10) with at least one permanent magnet (11) made of hard magnetic material is provided to provide a magnetic field (12) in the coupling gap (8),wherein at least one electrical control device (26) is provided, characterized in that at least one device (13) for reducing the basic friction is provided and that the electrical control device (26) is provided with an electronic full bridge.

Description

[0001] The present invention relates to a transmission device and a method for operating a transmission device, as well as a locking device or the like equipped with such a transmission device. For example, such a transmission device can be used to lock the steering movement of a vehicle in the manner of a steering wheel lock.

[0002] DE 10 2011 112 957 A1 and DE 10 61 578 B disclose devices with the features of the preamble of claim 1.

[0003] Steering wheel locks are one example of a device used to block a vehicle's steering movement. When locked, a bolt engages in a corresponding groove or opening, preventing any relative rotation between the two components. However, a disadvantage of such conventional steering wheel locks is that excessive overload can cause the bolts to break or shear off, after which the steering movement is no longer impeded, even if the lock itself is engaged.

[0004] Such a disadvantage is avoided if the steering lock is not based on a positive locking mechanism, but rather on a frictional locking mechanism. This involves pressing two friction discs together, one of which is stationary while the other rotates during steering. With the steering lock engaged, the frictional locking mechanism significantly hinders steering movement, but fundamentally prevents it. However, such a vehicle cannot be driven effectively because the steering forces are so great that while a steering movement might be possible once while stationary, it is not sustainable during continuous driving. A disadvantage of this state of the art is wear, as the brake discs used wear down over time, thus reducing the effectiveness of the steering lock.Furthermore, friction can be massively reduced by the accidental or intentional addition of lubricants.

[0005] Furthermore, transmission devices are known in which a magnetorheological fluid is provided in a magnetorheological coupling gap. When a magnetic field is applied, this fluid causes the magnetorheological particles to become linked, thus coupling the two components separated by the coupling gap. The strength of the coupling depends on the strength of the magnetic field and is inherently wear-free. The magnetic field can be varied as needed, for example, by means of an electrical coil, so that the rotational movement of the two components relative to each other can be slowed or even blocked. However, a disadvantage of such magnetorheological brakes or locking devices is that even when the magnetic field is switched off, a considerable and purely mechanical friction occurs through the coupling gap, which hinders the free rotation of, for example, the steering wheel.This negatively impacts the feedback between the road surface and the driver's steering feel, as even the smallest bumps and vibrations may be perceived only weakly, or not at all, by the driver's hand. This affects not only the driving feel but also driving safety, since feedback is essential for safe driving.

[0006] It is therefore the object of the present invention to provide a transmission device which has a long service life and in which the basic friction is low.

[0007] This problem is solved by a transmission device having the features of claim 1. Preferred embodiments of the invention are the subject of the dependent claims. Further advantages and features of the present invention will become apparent from the exemplary embodiments.

[0008] A transmission device according to the invention comprises a housing and at least two transmission components. A first transmission component includes a transmission shaft and a rotor and is rotatably arranged on the housing. The housing also includes at least one fluid chamber, which comprises a magnetorheological coupling gap with a gap width between the rotor of the first transmission component and a second transmission component of the at least two transmission components. The fluid chamber is provided with a magnetorheological fluid such that the coupling gap is at least partially, and in particular completely, filled with the magnetorheological fluid. At least one magnetic field source with at least one permanent magnet made of hard magnetic material is provided to generate a magnetic field in the coupling gap. At least one electrical control device is provided.Furthermore, at least one device for reducing basic friction is provided, which is particularly effective when the magnetic field is weak or switched off. The electrical control unit is a full-bridge electronic system.

[0009] The invention has many advantages. A significant advantage is that the transmission device according to the invention exhibits virtually no wear even after repeated use, so that the transmissible torque does not change, or changes only negligibly, over time. Furthermore, the device for reducing basic friction allows for smooth operation even when uncoupled, so that when used to lock the steering of a vehicle or similar device, precise feedback from the road surface to the user's steering wheel is possible due to the low basic friction.

[0010] In particular, the transmission device preferably comprises at least one adjustable magnetic field source with at least one electrical coil. The electrical coil is preferably designed to convert electrical pulses into magnetic pulses, which lead to a permanent change in the magnetic field of the magnetic field source. A targeted magnetic field can be set in the hard magnetic material of the permanent magnet via suitable pulses, which can then be released or remagnetized as needed by means of a suitable alternating field or suitable alternating electrical pulses.

[0011] In preferred embodiments of the invention, at least a part of at least one of the transmission components is arranged to be axially movable. In particular, at least a part of at least one of the transmission components is arranged to be axially movable during operation. For example, the first transmission component and / or the second transmission component can be arranged to be axially movable, either wholly or partially.

[0012] Preferably, the distance between the first transmission component and the second transmission component can be changed during operation.

[0013] Through this or one of the aforementioned further developments, it is possible to change the coupling gap during operation. By axially moving at least part of at least one transmission component, the gap width between the rotor of the first transmission component and a second transmission component can be changed during operation. With a small gap width, the effectiveness of the coupling between the two transmission components can be increased, since a strong magnetic field in the coupling gap leads to a corresponding linking of the magnetorheological fluid, resulting in a strong coupling between the two transmission components. Conversely, if the magnetic field is reduced or even switched off and the gap width of the coupling gap is additionally increased, the basic friction is significantly reduced.The strength of the fundamental friction depends significantly on the gap width between two bodies moving relative to each other. It is also possible that the gap length, rather than the gap width, varies. For example, if cylindrical transmission components are used, with one component radially surrounding the other, the gap length can be varied by adjusting the overlap between the two components. A greater overlap results in a longer axial gap length, which in turn increases the fundamental friction and the maximum transmissible torque. If the gap length is chosen to be large when the magnetic field is strong, and small when the magnetic field is weak or switched off, then only very low fundamental friction is present when the magnetic field is switched off. Varying the gap length can also be achieved, for example, using telescopic components.

[0014] In preferred embodiments, the rotor has at least one cylindrical, trough-shaped, hemispherical, frustoconical, pot-shaped and / or disc-shaped coupling surface. The rotor can be designed as a disc assembly or disc that is at least partially straight or curved.

[0015] Preferably, the coupling gap between the rotor and a counterbody is formed on the second transmission component. It is preferred that the counterbody has a suitably designed coupling surface that is at least partially adapted to the coupling surface of the rotor.

[0016] The rotor can be designed as a disk assembly, and the counterbody can have a counter disk between which the coupling gap is arranged. In preferred embodiments, the distance between the rotor and the counterbody is adjustable during operation. It is also possible, however, for the rotor to be axially adjustable relative to the first transmission component. Likewise, the counterbody can also be adjustable relative to the second transmission component. By adjusting the rotor and / or the counterbody relative to each other, the dimension of the coupling gap can be specifically changed during operation.

[0017] Preferably, the rotor is preloaded in the axial direction by a spring device. Particularly preferably, the rotor is pushed away from the second transmission component by a spring device.

[0018] If the rotor is pushed away from the counterbody and / or the counterbody is pushed away from the rotor, a larger gap width will initially be present in the ground state, resulting in a lower frictional torque in the ground state. If a rotational movement between the first and second transmission components is to be slowed, blocked, or otherwise hindered, the gap width between the rotor and the counterbody is reduced, and the magnetic field of the magnetic field source is increased or activated, for example, thus enabling effective torque transmission.

[0019] Preferably, the rotor is drawn towards the second transmission component when a magnetic field is activated or when the magnetic field of the magnetic field source is activated. In particular, a magnetic field of sufficient and typical strength from the magnetic field source overcomes the preload force of the spring device, so that the gap width of the coupling gap automatically decreases when a corresponding magnetic field is applied.

[0020] Preferred embodiments include a third transmission component, which can be coupled to the first transmission component via a controllable coupling device. The controllable coupling device is preferably at least partially integrated into the housing. Such a controllable coupling device enables targeted coupling and decoupling to the first transmission component, so that an increased base frictional torque between the first and second transmission components during normal operation with the coupling device decoupled does not negatively affect normal operation. The actual base friction in the decoupled state is then very low.

[0021] Preferably, the third transmission component comprises a rotatable working shaft or is connectable to such a rotatable working shaft, so that the transmission shaft can be selectively coupled to and decoupled from the working shaft. The purpose of the controllable coupling device is essentially to establish a digital and fixed coupling between the transmission shaft and the working shaft. When the third transmission component is coupled to the first transmission component, a rotationally fixed connection exists between the working shaft and the transmission shaft. When the third transmission component is decoupled from the first transmission component by means of the controllable coupling device, free and, in principle, undisturbed rotation of the working shaft relative to the transmission shaft is enabled.In the decoupled state, any potential basic friction between the first transmission component and the second transmission component no longer interferes with the function.

[0022] Preferably, a mechanically rotationally fixed connection between the third transmission component and the first transmission component is achieved using the controllable coupling device. For example, a rotationally fixed axial coupler can be provided on the working shaft, while a rotationally fixed counter-coupler is arranged on the transmission shaft. For torque transmission in the coupled state, the axial coupler and the counter-coupler are in engagement with each other. The axial coupler and the counter-coupler can be designed with axial teeth or as a type of tongue and groove or bolt and hole to enable a rotationally fixed connection between the axial coupler and the counter-coupler. Preferably, the maximum torque load capacity of the axial coupler or the counter-coupler is higher, and preferably considerably higher, than the maximum coupling possible across the coupling gap during normal operation.This ensures that in the event of an overload, the first and second transmission components rotate relative to each other at the coupling gap, rather than shearing off teeth, bolts, or similar parts on the axial coupler and the mating coupler. This guarantees continued reliable operation even under overload conditions.

[0023] The axial coupler and the counter-coupler can each be formed integrally with the working shaft or the transmission shaft, respectively, and can be arranged either fixedly or axially displaceably. For example, the axial coupler can be axially displaceable on the working shaft to enable coupling and decoupling of the controllable coupling device via axial movement. Similarly, the counter-coupler can be axially displaceable on the transmission shaft. In particular, even with axial displaceability and axial displacement of the axial coupler and / or the counter-coupler, rotationally fixed connections between the axial coupler and the working shaft, and between the counter-coupler and the transmission shaft, are maintained.

[0024] In preferred embodiments, the counter-coupler is axially fixed to the rotor. This means that an axial displacement of the counter-coupler also leads to an axial displacement of the rotor. Therefore, an axial displacement of the counter-coupler allows the coupling device to be decoupled or coupled, while simultaneously changing the gap width of the coupling gap.

[0025] In preferred embodiments, the controllable coupling device is preloaded into the decoupling position by a spring unit. The spring unit can be designed as a mechanical spring, but can also be pressurized or act via magnetic forces or the like.

[0026] Preferably, the controllable coupling device is forced into the engagement position by the magnetic field of the magnetic field source or by a magnetic field from another magnetic field source. For example, by generating a magnetic field with the magnetic field source, a spring force of the spring unit can be overcome, and the coupling device can be moved into the engagement position. This can be achieved, for example, by pulling a movable part, such as an axially movable axial coupler or an axially movable counter-coupler, into the engagement position in the axial direction, thus establishing coupling. In such a configuration, it is possible, for example, to provide a magnetic field source at the coupling gap that comprises only a permanent magnet and, optionally, no electrical coil. This permanently generates a magnetic field of a predetermined strength in the coupling gap.For example, an additional magnetic field source, equipped with an electrical coil, can generate an adjustable magnetic field at this source. This field can be switched on, reduced, or completely switched off. The magnetic field of this additional source can then force the coupling device—possibly against the force of a spring assembly—from the disengaged position into the engaged position. Only then is the first transmission component coupled to the third, causing the magnetic field of the source to block or impede the rotation of the transmission shaft at the coupling gap. Since the transmission shaft is coupled to the working shaft in this state, the rotation of the working shaft is also blocked or at least impeded as desired.

[0027] If the additional magnetic field source is equipped with an electric coil and a permanent magnet, the hard magnetic material can be permanently magnetized as desired via a control unit and the output of electrical pulses, so that a permanent coupling via the controllable coupling device exists even after the power source is switched off. This means that even after switching off or removing a power connection, relative movement between the first and second transmission components is blocked.

[0028] In such configurations, where an effective coupling between the first and second transmission components is achieved via an adjustable or permanently acting magnetic field, the required low basic friction can be achieved by decoupling with the controllable coupling device. The coupling and decoupling of the coupling device preferably occurs via magnetic forces, but can also be accomplished via an electric motor or the like. Coupling and decoupling the controllable coupling device via remanence has the advantage that applying or removing an electrical voltage or current does not result in a transition from a coupled to a decoupled state or vice versa.

[0029] For the purposes of this application, a magnet is referred to as a permanent magnet if its magnetic field strength remains at least substantially constant and unchanged. A permanent magnet is understood to be a magnet made of hard magnetic materials whose magnetic field strength is permanently altered by an electric coil. Here, the remanence of the material is utilized, so that the magnetic field of the permanent magnet can be permanently set by short electrical pulses from the electric coil. The magnetic field is maintained even after the electric current to the coil is switched off. The field strength of the permanent magnet can be reset or adjusted as desired by means of an alternating field or suitable alternating pulses with decreasing intensity.

[0030] A magnetic field source according to the present invention can comprise one or more permanent magnets and one or more electrical coils. It is also possible for a magnetic field source to comprise only one electrical coil and / or only one permanent magnet for generating a magnetic field.

[0031] In a preferred embodiment, the magnetic field source comprises at least one permanent magnet made of a hard magnetic material, and an electrical control device is provided and configured to selectively and permanently influence the magnetic field of the magnetic field source by outputting electrical pulses. This allows coupling and / or decoupling of the controllable coupling device or the generation of an adjustable magnetic field in the coupling gap.

[0032] In all embodiments, it is preferred that a storage device for the intermediate storage of electrical energy is provided. Such a storage device can, for example, be implemented as a capacitor or at least comprise a capacitor. A capacitor or other electrical storage device makes it possible to temporarily store the required electrical energy, for example, to precisely adjust the magnetic field of a permanent magnet. Furthermore, a capacitor, for example, makes it possible to use electrical cables or conductors designed for lower currents and to design only the short cables between the capacitor and the electrical coil for the required current.

[0033] Preferred advanced training programs include an electrical control unit with an electronic full bridge. Such a bridge circuit makes it easy to generate an alternating field for demagnetizing or remagnetizing.

[0034] In all embodiments, the device for reducing the base load torque may include, or be formed by, a widening of the coupling gap in the rotor and / or in the second transmission component. Such a widening can be formed, for example, by one or more recesses in the rotor and / or in the second transmission component. These recesses or widenings of the coupling gap on the relative rotating parts achieve a significant reduction in the base load torque or base friction, since the local gap width has a considerable effect on the base friction. A larger gap width leads to lower base friction because surface effects have a lesser influence.

[0035] It is possible that the device for reducing the basic load moment consists of only one or more recesses. It is also possible that the device for reducing the basic load moment or basic friction, in addition to a recess, also includes a device for adjusting the gap width or at least one dimension of the coupling gap.

[0036] In all embodiments, it is preferred that a coupling between the transmission components cannot be completely disengaged and / or established by interrupting the power supply or by applying a constant current. This achieves improved safety conditions, since, for example, a user who wishes to use a vehicle without authorization cannot cause a complete disengagement or coupling between the transmission components, even by applying a constant current or constant voltage to the transmission device.

[0037] In a further embodiment, the transmission device comprises a housing and at least two transmission components. A first transmission component comprises a transmission shaft and a rotor and is rotatably arranged in or on the housing. A fluid chamber is provided on the housing, which includes a magnetorheological coupling gap with a gap width between the rotor of the first transmission component and a second transmission component. The fluid chamber is filled with a magnetorheological fluid such that the coupling gap is at least partially filled with the magnetorheological fluid. At least one magnetic field source with at least one permanent magnet made of hard magnetic material is provided to generate a magnetic field in the coupling gap.The magnetorheological coupling gap has a gap width perpendicular to a connecting line between the first and second transmission components that is greater than 1.5 mm.

[0038] Such a wide coupling gap results in low base friction when the magnetic field is switched off or weak. While prior art magnetorheological coupling gaps of less than 0.5 mm or less than 1.0 mm are used to achieve high efficiency in generating a magnetic field, the opposite approach is taken here: the coupling gap is made very large to reduce base friction. This is particularly important during steering movements, as it can significantly interfere with the vehicle's operation. Therefore, the safety of the vehicle's movement can also be improved.

[0039] A disclosed blocking device comprises at least one transmission device as previously described. The control device allows for the selective switching on and off of a magnetic field from at least one magnetic field source. The magnetic field of at least one magnetic field source is permanently influenced by electrical impulses from the electrical coil, such that when the magnetic field is switched on, the rotation of the first transmission component relative to the second transmission component is permanently blocked or at least significantly slowed. When the magnetic field is switched off, the rotation of the first transmission component relative to the second transmission component is essentially unimpeded.

[0040] The disclosed method serves to operate a magnetorheological transmission device, wherein a coupling of a first and a second transmission component to each other is effected via a coupling gap filled with a magnetorheological fluid. An electrical pulse from an electric coil permanently alters the magnetic field of a magnetic field source in order to switch the coupling on or off. When a magnetic field from the magnetic field source is activated, a dimension of the coupling gap is changed such that, at least with a weaker magnetic field, a larger coupling gap is present than with at least one stronger magnetic field.

[0041] In all configurations, it is possible to install a sensor, such as a Hall sensor, in the transmission device or coupling to measure the magnetic field strength and, consequently, to selectively modify the magnetic field. This can be achieved using an electrical coil that generates an (additional) magnetic field, or by having the electrical coil emit targeted pulses to adjust the magnetic field of a permanent magnet as desired.

[0042] Overall, a transmission device is provided which, via a magnetorheological coupling gap, offers an adjustable coupling strength between two transmission components. In particular, a permanent magnetic field is provided via the remanence properties of an adjustable permanent magnet, which can be adjusted by magnetic pulses from an electrical coil. In preferred embodiments, a cup-shaped construction can be used, in which there are only a small number of sealing points and, in particular, only a single seal, thus enabling a lower initial torque or lower initial friction. In the event of an overload, i.e., if the intended braking torque is exceeded, no positive-locking pin, bolt, or the like of a steering lock is sheared off; instead, movement is only possible, during which the full braking torque is still effective.Significant forces are required to exceed the braking torque and thus initiate a rotational movement. Such a system cannot be switched on or off by an interruption of the power supply, nor can it cause the steering to lock up in the event of a malfunction. An alternating field is preferably used for demagnetization, which cannot be generated simply by applying current. The transmission device functions continuously and is virtually wear-free.

[0043] Even with changes in gap dimensions, for example due to assembly, the clutch torque changes only negligibly. Furthermore, the clutch torque does not result from the product of the coefficient of friction and the normal force, but rather from the magnetic field strength. With conventional friction discs, the coefficient of friction can be significantly reduced, for example, by greasy hands during assembly or by adding lubricant, so that there is little or no locking effect.

[0044] Any intermediate magnetic field strength can be easily and permanently set via remanence, for example. When using remanence, both the "active state" and the "deactivated state" can be maintained without continuous power supply. Magnetization can be set silently via a current pulse lasting less than 100 milliseconds. The operating voltage is adjustable.

[0045] Control via a microcontroller is easily possible. Authorization queries can be meaningfully integrated.

[0046] Further advantages and features of the present invention will become apparent from the exemplary embodiments, which are explained below with reference to the accompanying figures.

[0047] The figures show: Fig. 1 a schematic perspective view of a transmission device according to the invention; Fig. 2 the transmission device according to the invention Fig. 1 in a schematic section in two states; Fig. 3 a further transmission device according to the invention to a first state; Fig. 4 the transmission device according to Fig. 3 in a second position; Fig. 5 another transmission device according to the invention; Fig. 6 a schematic cutaway representation of another transmission device according to the invention; Fig. 7 another transmission device according to Fig. 1 in an exploded view; and Fig. 8 a schematic cutaway view of the transmission device according to Fig. 7.

[0048] Fig. Figure 1 shows a perspective view of a transmission device 1, which has a housing 2, the housing 2 being closed by a cover 44. Cables 35 serve for the electrical connection in order to supply the required current to an electrical coil 21 or 22 provided inside, which is not visible here.

[0049] The transmission shaft 9, whose rotational movement can be slowed or blocked, is visible through an opening in the cover 44. The transmission device 1 is intended here for use in a steering system of a vehicle, and in particular a motor vehicle. The transmission device 1 according to the invention replaces a conventional steering lock and blocks the steering movement in the activated state. For this purpose, a coupling gap 8 (cf. e.g. Fig. 2) generates a magnetic field 12 which leads to a chaining of the magnetorheological particles of the magnetorheological fluid 20 present there.

[0050] The transmission device 1 is in Fig. Figure 2 is shown in a schematic cross-sectional view in two different positions. The left half of shows... Fig. 2 the ground state, in which there is very low ground friction. The transmission device 1 has a first transmission component 3 and a second transmission component 4, between which an approximately conical coupling gap 8 is provided. The coupling gap 8 is part of a fluid chamber 7, which is at least partially and in particular completely filled with a magnetorheological fluid 20.

[0051] In the left half of Fig. In the basic state shown in Figure 2, there is a large gap width 18, which can be 2 mm, 3 mm, or more. This results in a very low basic friction when the rotor 6 of the first transmission component 3 rotates. With smaller coupling gaps 8, the basic torque or basic friction increases considerably because the coupling surfaces 28 on the rotor 6 of the first transmission component 3 and on the counter body 16 of the second transmission component 4 generate high basic friction due to the small gap width 18. This basic friction decreases considerably as the gap width 18 increases. Therefore, when used as a steering lock in the deactivated state, the damping or negative influence of basic friction on tactile feedback is reduced. This also increases driving safety, as road surface influences are transmitted directly to the steering wheel, so that the driver receives virtually undisturbed feedback about the driving characteristics.

[0052] In the transmission device 1 in Fig. 2 A device 13 is provided for reducing the basic torque or basic friction. This device 13 is formed by arranging at least the rotor 6 of the first transmission component 3 to be axially movable relative to the second transmission component 4. This allows, as can be seen by comparing the left half of Fig. 2 with the right half of the Fig. As is readily apparent, the clutch gap 8 is considerably enlarged, thereby reducing the basic friction in the switched-off state. However, when used as a steering lock, if the relative movement of the first transmission component relative to the second transmission component 4 is braked, a small gap width 18 of the clutch gap 8 is set. Then, the magnetic field 12 in the clutch gap 8 causes an effective interlinking of the magnetorheological particles in the magnetorheological fluid.

[0053] Such a magnetic field 12 is preferably only activated when the steering lock is engaged or the parking brake is applied. The strength of the coupling between the first transmission component 3 and the second transmission component 4 can be adjusted via the strength of the magnetic field.

[0054] In this exemplary embodiment, a spring device 17 is provided, which can be designed as a coil spring or is based, for example, on magnetic forces or the like, and which preloads at least the rotor 6 of the first transmission component 3 in the axial direction away from the second transmission component 4. This results in a larger gap width 18 in the basic state.

[0055] Preferably, the magnetic field 12 generates a counterforce to the spring device 17, so that the gap width 18 of the coupling gap 8 is reduced when the magnetic field is activated. While this also increases the basic friction, the purpose of this state is to dampen the relative movement of the first transmission component 3 to the second transmission component 4.

[0056] The first transmission component 3 and the second transmission component 4 are arranged symmetrically about the axis 36. The second transmission component 4 is fixedly attached to the housing 2, while the first transmission component 3 is rotatably arranged around the axis 36 with the transmission shaft 9.

[0057] Here, it is possible that the transmission shaft 9, together with the rotor 6, is designed to be axially displaceable. However, it is also possible that the rotor 6 is rotationally fixed to the transmission shaft 9, but is arranged to be axially displaceable on the transmission shaft 9 in order to increase and decrease the coupling gap 8.

[0058] Fig. Figure 3 shows a further embodiment of the transmission device according to the invention in a first position, namely the basic position, in which a relatively large gap width 18 exists between the rotor 6 of the first transmission component 3 and the second transmission component 4. The device 13 is again provided here by the adjusting units for adjusting the gap width.

[0059] Here too, the housing 2 is approximately pot-shaped, and the second transmission component is fixedly connected to the housing, while the first transmission component 3 is rotatably mounted on the housing 2 with the transmission shaft 9 via a bearing 37. A seal 38 seals the interior of the housing 2 from the outside.

[0060] In the housing 2, a coil 21, or two coils 21 and 22, are arranged approximately in a ring shape around the central axis 36, with a permanent magnet 11 made of a hard magnetic material being arranged on the coil 21 or between the coils 21 and 22. A pole ring and a pole disk can serve to conduct the magnetic field 12.

[0061] Furthermore, the interior of the housing 2 is provided with a fluid chamber 7, which is at least partially filled with a magnetorheological fluid, and in particular with a liquid 20. This fills the coupling gap 8 between the rotor 6 and the second transmission component 4, in particular with a magnetorheological fluid. The gap width 18 of the coupling gap 8 can be varied.

[0062] In Fig. 3 shows a larger gap width than in Fig. 4. This results in the following in the basic position according to Fig. 3 a low base friction is provided while in the working position according to Fig. Although there is a higher basic friction at position 4, this is not a problem, as this indicates the braking or locking position, in which a rotational movement between the rotor 6 and the second transmission component 4 is to be slowed or even blocked. To adjust the gap width 18, the first transmission component 3, together with the rotor 6, or just the rotor 6 as the adjustable part 14, is moved axially.

[0063] Fig. Figure 5 shows another embodiment of a transmission device 1 according to the invention, in which the gap width 18 between the rotor 6 of the first transmission component 3 and the second transmission component 4 is also adjustable. This means that in the braking position there is a smaller gap width 18 than in the normal position, in which a rotational movement between the first transmission component 3 and the second transmission component 4 should be as undisturbed as possible. In the embodiment according to Figure 5, the gap width 18 is adjusted as follows: Fig. In embodiment 5, the rotor 6 is axially adjusted together with the transmission shaft 9 as a device 13. However, it is also possible for the rotor 6 to be axially adjusted on the transmission shaft 9. The gap width 18 can preferably be adjusted by more than a factor of 2 and preferably by more than 1 mm in all embodiments.

[0064] Additionally, in the exemplary embodiment according to Fig. 5 A controllable coupling device 23 is provided, which selectively couples or decouples a third transmission component 5 to the first transmission component 3. For coupling the third transmission component 5 to the first transmission component 3, the end face of the transmission shaft 9 of the first transmission component 3 and the end face of the working shaft 19 of the third transmission component 5 each have axial teeth or interlocking projections, with which a rotationally fixed coupling of the transmission shaft 9 and the working shaft 19 can be achieved.

[0065] Fig. Figure 5 shows the decoupling position 33, in which the third transmission component 5 is decoupled from the first transmission component 3, allowing independent rotational movement of transmission components 3 and 5. An axial movement of the first transmission component 3 couples transmission components 3 and 5 to each other in a rotationally fixed manner, and simultaneously reduces the gap width 18 of the coupling gap 8, thus combining a high coupling strength in the activated state with low basic friction in the decoupled state. The device 13 is provided here by the coupling device 23.

[0066] Fig. Figure 6 shows a schematic representation of another variant of the transmission device 1 according to the invention. The transmission device 1 is controlled by the control unit 26. Power can be supplied by the capacitor 29. The transmission device 1 comprises a housing 2 and first and second transmission components 3 and 4 arranged therein. A third transmission component 5 can be coupled to a working shaft 19 via a coupling device 23. The device 13 can consist only of the coupling device 23 or include further components. An axial coupler 24 is provided at the end of the working shaft 19 for the mechanical coupling of the coupling device 23. The first transmission component 3 has a counter-coupler 25 at the end of the transmission shaft 9.The first transmission component 3 and / or the third transmission component 5 are at least partially axially movable, so that a rotationally fixed connection between the two transmission components 3 and 5 can be established via the axial coupler 24 and the counter-coupler 25. If only the counter-coupler 25 and / or the axial coupler 24 is moved in the axial direction, the transmission shaft 9 and / or the working shaft 19 remain stationary, regardless of whether the decoupling position 33 or the engagement position 34 is present.

[0067] It is therefore possible that the gap width 18 between the rotor 6 and the second transmission component 4 remains the same in all cases or is variable. In a simple case, the gap width 18 of the coupling gap 8 remains constant. In the coupling gap 8, the magnetorheological fluid there binds together depending on the existing or generated magnetic field 12. As in the lower half of Fig. As shown in Figure 6, a permanent magnet 31 with a constant field strength can be provided on the second transmission component 4, generating a magnetic field 12 in the coupling gap 2 such that the relative movement of the first transmission component 3 relative to the second transmission component 4 is strongly slowed or blocked. The strength of the braking or blocking can be adjusted via the strength of the magnetic field.

[0068] However, it is also possible that, as in the upper part of the Fig. Figure 6 shows an electric coil 21 together with a permanent magnet 11, which together form the magnetic field source 10. The permanent magnet 11, made of hard magnetic material, is magnetized as desired by short, sufficiently strong magnetic pulses from the electric coil 21. The magnetic field remains permanently present. The strength of the coupling between the transmission components 3 and 4 can be varied as needed. Demagnetization is possible by correspondingly alternating pulses or an alternating magnetic field.

[0069] This enables the transmission device 1 according to Fig. 6 a low basic friction in conjunction with a desired high braking effect between the transmission components 3 and 4 or 3 and 5. By means of the coupling device 23, the frictional torque acting in the basic state can be reduced to practically 0.

[0070] It is possible that the axial displacement of the rotor 6 and / or the axial coupler 24 or the counter-coupler 25 occurs against a preload force of the spring assembly 17 and / or the spring unit 27. The axial movement can be achieved by magnetic forces. For example, if the parking brake is to be activated, a magnetic field 12 can be permanently stored in the permanent magnet 11 via the electric coil 11, which directly leads to an axial displacement of the rotor 6 and / or the transmission shaft 9, so that the coupling device 23 is moved into and maintained in the engaged position 34.

[0071] Similarly, a corresponding movement of the axial coupler 24 relative to the working shaft 19 or a relative movement of the working shaft 19 with the axial coupler 24 against the force of the spring unit 27 is possible if a further magnetic field source 30 generates a corresponding magnetic field.

[0072] Fig. Figure 7 shows an exploded view of another transmission device 1 according to Fig. 1, where in the embodiment shown here according to the Fig. 7 and Fig. 8 The device 13 for reducing the basic friction is formed by recesses 32 on the rotor 6. While the coupling gap 8 or its gap width 18 can generally be varied, but does not have to be, here the coupling gap 8 is locally widened by the recesses 32. This reduces the respective basic friction in the areas with the widened coupling gap, resulting in a significantly lower overall basic friction. In addition, the gap width 18 of the coupling gap 8 can be increased to 1.5 mm or more, so that an overall lower basic friction can be achieved.

[0073] A pole disk 40 is fastened in the housing 2 by means of a screw 41. A central opening in the housing accommodates the transmission shaft 9. A coil unit 39 with a magnetic ring 45 and a ring 42 forms part of the second transmission component 4, to which the coupling gap 8 adjoins. The rotor 6, which has a recess 32 around its axis, is provided in the coupling gap 8.

[0074] The O-ring 43 and the cover 44 are attached to the rotor 6, the latter being fastened via washers 46 and screws 41.

[0075] Overall, an advantageous transmission device is provided that combines low basic friction with high load capacity, low wear, and high operational reliability. Furthermore, its function cannot be disrupted by overload. Reference symbol list: 1 transmission device 2 cases 3 1. Transmission component 4 2. Transmission component 5 3. Transmission component 6 Rotor 7 Fluid chamber 8 Clutch gap 9 transmission wave 10 Magnetic field source 11 Permanent magnet 12 Magnetic field 13. Facility Part 14 16 Counterbodies 17 Spring assembly 18 gap width 19 work wave 20 magnetorheological fluid 21 electrical coil 22 electrical coil 23 Coupling device 24 axial couplers 25 anticouplers 26 Control unit 27 Spring unit 28 coupling surface 29 Storage device 30 more magnetic field sources 31 Permanent magnet 32 Exclusion 33 Decoupling position 34 Intervention position 35 cables 36 axle 37 warehouses 38 Seal 39 coil unit 40 Polaring disc 41 screw 42 Ring 43 O-ring 44 lids 45 Magnetic ring 46 discs

Claims

Transmission device (1) with a housing (2) and at least two transmission components (3, 4), wherein a first (3) of the transmission components (3) comprises a transmission shaft (9) and a rotor (6) and is rotatably arranged on the housing (2), wherein a fluid chamber (7) is provided on the housing (2), which comprises a magnetorheological coupling gap (8) with a gap width (18) between the rotor (6) of the first transmission component (3) and a second transmission component (4) of the transmission components (3, 4), wherein the fluid chamber (7) is provided with a magnetorheological fluid (20) such that the coupling gap (8) is at least partially filled with the magnetorheological fluid (20), and wherein at least one magnetic field source (10) with at least one permanent magnet (11) made of hard magnetic material is provided to provide a magnetic field (12) in the coupling gap (8),wherein at least one electrical control device (26) is provided, characterized in that at least one device (13) for reducing the basic friction is provided and that the electrical control device (26) is provided with an electronic full bridge. Transmission device (1) according to claim 1, wherein at least a part (14, 24) of at least one of the transmission components (3, 4, 5) is axially movable and / or wherein a distance between the first and the second transmission component (3, 4) is variable during operation. Transmission device (1) according to one of the preceding claims, wherein the rotor (6) has at least one cylindrical, trough-shaped, half-shell-shaped, frustoconical, pot-shaped or disc-shaped coupling surface (28). Transmission device (1) according to one of the preceding claims, wherein the coupling gap (8) is formed between the rotor (6) and a counter body (16) on the second transmission component (4). Transmission device (1) according to one of the preceding claims, wherein the rotor (6) is preloaded in the axial direction by a spring device (17) and / or wherein the rotor (6) is pushed away from the second transmission component (4) by a spring device (17). Transmission device (1) according to one of the preceding claims, wherein the rotor (6) is pulled towards the second transmission component when the magnetic field (12) is activated or when the magnetic field (12) of the magnetic field source (10) is activated. Transmission device (1) according to one of the preceding claims, wherein a third transmission component (5) is provided which can be coupled to the first transmission component (3) via a controllable coupling device (23). Transmission device (1) according to the preceding claim, wherein the third transmission component (5) has a rotatable working shaft (19) which can be selectively coupled and uncoupled to the transmission shaft (9). Transmission device (1) according to one of the preceding claims, wherein the controllable coupling device (23) comprises an axial coupler (24) connected to the working shaft (19) in a rotationally fixed manner and a counter-coupler (25) connected to the transmission shaft (9) in a rotationally fixed manner, which are in engagement with each other for torque transmission. Transmission device (1) according to one of the preceding claims, wherein the controllable coupling device (23) is preloaded into the decoupling position (33) by a spring unit (27). Transmission device (1) according to one of the preceding claims, wherein the coupling device (23) is forced into the engagement position (34) by the magnetic field (12) of the magnetic field source (10) or a magnetic field of a further magnetic field source (30). Transmission device (1) according to one of the preceding claims, wherein the magnetic field source (10, 30) comprises at least one electrical coil (21) and / or at least one permanent magnet (31). Transmission device (1) according to one of the preceding claims, wherein at least one magnetic field source (10, 30) comprises at least one permanent magnet (11) made of a hard magnetic material and wherein the electrical control device (26) is provided and configured to permanently and selectively influence the magnetic field (12) of the magnetic field source (10, 30) by means of the output of electrical impulses. Transmission device (1) according to one of the preceding claims, wherein a storage device (29) is provided to store electrical energy. Transmission device (1) according to one of the preceding claims, wherein the device (13) for reducing the base load torque comprises a widening of the coupling gap (8) by means of a recess (32) in the rotor (6) or in the second transmission component (4). Transmission device (1) according to one of the preceding claims, wherein a coupling between the transmission components (3-5) cannot be completely released and / or established by cutting the power supply or by applying constant current.

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