Fluid friction device with speed compensation

Abstract

comprising fluid friction device (10) a housing (12) for receiving a fluid, a connecting component (22), a drive component (20) rotatable about an axis of rotation (18) and relative to the connecting component (22), a lamellar section (24) effectively arranged between the drive component (20) and the connecting component (22), which frictionally couples the drive component (20) to the connecting component (22) for the transmission of a torque via the fluid in at least one shear gap (30) of the lamellar section (24), an axially displaceable actuation element (48) for adjusting a gap width (b) of the shear gap (30) and a spring element (62) that exerts a spring force (F) acting in the direction of the lamellar area (24) on the actuation element (48), wherein the actuation element (48) is axially displaceable by a fluid pressure in a compensation chamber (50) separated from the lamellar area (24) against the spring force (F) of the spring element (62) depending on the rotational speed, characterized in that a further axial displacement (x) of the actuation element (48) in the axial direction towards the lamellar area (24) is limited by an axial locking element (70).

Description

[0001] The invention relates to a fluid friction device according to claim 1.

[0002] Such a fluid friction device can support the torque of a rotatable drive component relative to a housing-fixed connecting component and can thus be used as a fluid-acting retarder or as a fluid-acting brake. For example, reference is made to EP 2 884 130 A1, which describes a fluid friction device as an auxiliary brake, particularly for means of transport.

[0003] The torque that can be transmitted via a shear stress in a fluid of the fluid friction device between the drive component and the connecting component usually depends proportionally on the speed.

[0004] As a strand of the art, reference is made, for example, to CN 2 222 829 Y and CN 1 02 913 562 A, each of which discloses a fluid friction device which can be read in the preamble of patent claim 1.

[0005] The object of the present invention is to reduce the speed dependence of the transmittable torque.

[0006] At least one of these objects is achieved by a fluid friction device having the features of claim 1. This counteracts the speed-dependent variation in the transmittable torque. This allows self-regulation of the transmittable torque across the entire speed range.

[0007] The fluid friction device can be arranged in a vehicle. The torque transmitted via the fluid friction device can be a thrust torque generated by a vehicle movement, in particular a thrust torque generated via the vehicle's wheels.

[0008] The fluid friction device can be a fluid friction brake or a multi-disk retarder.

[0009] The fin area can be arranged within the housing. The fins can be arranged in the fluid and designed as wet-running fins.

[0010] The connecting component can be arranged fixedly to the housing. The connecting component can be firmly connected to the housing, in particular, it can be constructed as a single piece.

[0011] In a preferred embodiment of the invention, it is advantageous if the fluid pressure in the compensation chamber is speed-dependent, as a centrifugal force-dependent fluid pressure. The fluid can be an oil. The compensation chamber can be a centrifugal oil chamber. As the speed increases, the fluid pressure increases due to the centrifugal force.

[0012] A preferred embodiment of the invention is advantageous in which the lamella region comprises at least one drive-side lamella connected to the drive component and at least one connection-side lamella connected to the connecting component. The connecting component can be designed as a lamella carrier, in particular as an outer lamella carrier, that accommodates at least one connection-side lamella.

[0013] The drive component can be designed as a disk carrier, in particular as an inner disk carrier, that accommodates at least the drive-side disk. A reversed arrangement of the outer disk carrier and inner disk carrier is also possible. The drive component can be connected to a drive shaft in a rotationally fixed manner. The drive component and the drive shaft can be designed as a single piece.

[0014] In a preferred embodiment of the invention, it is advantageous if the shear gap is arranged axially between the drive-side and connection-side lamellae. The lamella area can have several drive-side and connection-side lamellae and thus a number n of shear gaps. The possible gap width b of the respective shear gap depends on the axial displacement x as follows: b=xn

[0015] A preferred embodiment of the invention is advantageous in which the speed-dependent axial displacement of the loading element is designed such that the gap width increases with increasing speed. This allows the transmittable torque to be more uniform across the speed. The gap width can increase proportionally with the speed. Since the transmittable torque is proportional to the ratio of the speed to the gap width, a ratio of the speed to the gap width that is as constant as possible can enable a transmittable torque that is as constant as possible across all speeds.

[0016] In a preferred embodiment of the invention, it is advantageous if the speed-dependent axial displacement depends on a spring characteristic of the spring element. The speed-dependent axial displacement can also depend on the dimensions of a region of the loading element exposed to the fluid pressure and / or fluid parameters, in particular the fluid density.

[0017] In a special embodiment of the invention, it is advantageous if the spring characteristic curve is designed such that the spring force is quadratically proportional to the axial displacement. The spring force F can have the following relationship: F=F0+c⋅x2 with the preload force F0 at the axial displacement of x = 0 and the axial displacement x, as well as the spring stiffness c.

[0018] In a special embodiment of the invention, it is advantageous if the spring element is a disc spring which, particularly over a partial range of the axial displacement, is in a flat position causing the quadratic relationship between the spring force and the displacement. The disc spring can be used starting at the axial displacement x0: x = 0 up to the maximum axial displacement x max be consistently flat.

[0019] In a special embodiment of the invention, it is advantageous if the spring force acts on the loading element over the entire axial displacement of the loading element. The spring force can be equal to the preload force F0 at the axial displacement x0: x = 0, corresponding to an axial position closest to the lamella area. At an axial position furthest from the lamella area, corresponding to a maximum axial displacement x = x max the spring force is maximum with Fmax=F0+c⋅xmax2. .

[0020] According to the invention, it is advantageous if further axial displacement of the loading element in the axial direction toward the lamella area is limited by an axial locking element. This allows a minimum gap width to be set and implemented.

[0021] Further advantages and advantageous embodiments of the invention emerge from the description of the figures and the illustrations. Character description

[0022] The invention is described in detail below with reference to the figures. They show in detail: Fig. 1: A half-section of a fluid friction device in a specific embodiment of the invention. Fig. 2: A characteristic diagram of a fluid friction device in another specific embodiment of the invention.

[0023] Fig. Figure 1 shows a half-section of a fluid friction device in a specific embodiment of the invention. The fluid friction device 10 is designed, for example, as a fluid friction brake or a multi-disk retarder and comprises a housing 12 for accommodating a fluid. The housing 12 is constructed in two parts, with a first housing part 14 and a second housing part 16 firmly connected thereto.

[0024] The fluid friction device 10 further comprises a drive component 20 rotatable about a rotational axis 18, a housing-fixed connecting component 22 relative to which the drive component 20 is rotatable, and a lamella region 24 arranged within the housing 12 and effectively arranged between the drive component 20 and the connecting component 22.

[0025] The lamella region 24 comprises a plurality of drive-side lamellae 26 connected to the drive component 20 and a plurality of connection-side lamellae 28 connected to the connection component 22. The lamella region 24 couples the drive component 20 to the connection component 22 for transmitting torque via the fluid in a shear gap 30 of the lamella region 24, which is arranged axially between the drive-side and connection-side lamellae 26, 28. The fluid arranged in the respective shear gap 30 effects a torque transmission between the respective drive-side lamellae 26 and the connection-side lamellae 28 through the shear stress of the fluid in the corresponding shear gap 30.

[0026] The drive component 20 is designed as a disk carrier 32, here an inner disk carrier 34, which accommodates the drive-side disks 26. The inner disk carrier 34 is rigidly connected to a drive hub 36, which in turn is rotationally fixedly connected to a drive shaft 38. The drive hub 36 is rotatably mounted relative to the second housing part 16 via a bearing element 40. The drive shaft 38 is rotatably mounted relative to the first housing part 14 via a further bearing element 42.

[0027] The connecting component 22 is designed as a further lamella carrier 44, here as an outer lamella carrier 46, which receives the connection-side lamellae 28 and is firmly connected to the second housing part 16.

[0028] The fluid friction device 10 further comprises an axially displaceable loading element 48 for adjusting a gap width b of the shear gap 30. The torque transmittable via the lamella region 24 is inversely proportional to the gap width b and in turn proportional to a differential speed between the drive component 20 and the connecting component 22 and, since the connecting component 22 is fixed to the housing here, to a speed of the drive component 20.

[0029] The pressure element 48 is pot-shaped and partially forms a boundary of a compensation chamber 50, which is connected to a fluid line 54 via a fluid opening 52 in the drive hub 36. The fluid line 54 has a further connection 56 to the lamella region 24. The compensation chamber 50 is defined by a wall 58, which is received on the drive hub 36. The pressure element 48 is sealed from the wall 58 and the drive hub 36 by a seal 60. The wall 58 is also sealed from the drive hub 36 by a sealing element 60.

[0030] A spring element 62 applies a spring force F to the application element 48 in the direction of the lamella region 24. The spring element 62 is designed as a disc spring 66, which is supported on the one hand by a retaining ring 68 on the drive hub 36 and, on the other hand, bears against the application element 48. However, an axial displacement x of the application element 48 in the direction of the lamella region 24 is limited by an axial securing element 70, which is accommodated in the drive hub 36. This allows a minimum gap width b of the respective shear gap 30 to be maintained.

[0031] The loading element 48 is axially displaceable, depending on the speed, by a fluid pressure in the compensation chamber 50 separated from the lamella area 24, against the spring force F of the spring element 62. The fluid pressure is a centrifugal force-dependent fluid pressure. This allows the gap width b to increase with increasing speed. The relationship between the gap width b and the speed can be adjusted, on the one hand, via the dimensions of the loading element 48 exposed to the fluid pressure and, on the other hand, via the spring characteristic curve of the spring element 62.

[0032] If the spring element 62 is a disc spring 66, as shown here, it can be applied to the loading element 48 over the entire axial displacement x of the loading element 48, exerting a force. Preferably, the spring force F is quadratically proportional to the axial displacement x. Such a spring characteristic can be achieved by a flat position of the disc spring 66 on the loading element 48.

[0033] Fig.Figure 2 shows a characteristic diagram of a fluid friction device in another specific embodiment of the invention. It shows the curve of the transmittable torque M versus the speed ω and the curve of the gap width b versus the speed ω. The gap width b increases approximately linearly with increasing speed ω at higher speeds ω. The transmittable torque M increases only minimally with the speed ω, allowing the transmittable torque M to be designed more uniformly and independently of the speed ω. List of reference symbols 10 Fluid friction device 12 housings 14 first housing part 16 second housing part 18 axis of rotation 20 drive component 22 Connection component 24 slat area 26 drive-side slats 28 connection-side slats 30 Shear gap 32 slat carriers 34 inner disc carrier 36 drive hub 38 Drive shaft 40 bearing element 42 additional bearing element 44 additional slat carriers 46 outer disc carrier 48 loading element 50 compensation chamber 52 Fluid opening 54 Fluid line 56 connection 58 Wall 60 Seal 62 spring element 66 disc spring 68 Retaining ring 70 Axial locking element F spring force M transmittable torque ω speed b gap width x axial displacement

Claims

[1] Fluid friction device (10) comprising a housing (12) for receiving a fluid, a connecting component (22), a drive component (20) rotatable about an axis of rotation (18) and relative to the connecting component (22), a lamella region (24) arranged operatively between the drive component (20) and the connecting component (22), which frictionally couples the drive component (20) to the connecting component (22) for transmitting a torque via the fluid in at least one shear gap (30) of the lamella region (24), an axially displaceable loading element (48) for adjusting a gap width (b) of the shear gap (30) and a spring element (62) which exerts a spring force (F) acting on the loading element (48) in the direction of the slat area (24), wherein the loading element (48) is axially displaceable by a fluid pressure in a compensation chamber (50) separated from the lamella region (24) against the spring force (F) of the spring element (62) in a speed-dependent manner, characterized by that a further axial displacement (x) of the loading element (48) in the axial direction towards the lamella region (24) is limited by an axial securing element (70). [2] Fluid friction device (10) according to claim 1, characterized by that the fluid pressure in the compensation chamber (50) is speed-dependent as a centrifugal force-dependent fluid pressure. [3] Fluid friction device (10) according to claim 1 or 2, characterized by that the slat region (24) has at least one drive-side slat (26) connected to the drive component (20) and at least one connection-side slat (28) connected to the connection component (22). [4] Fluid friction device (10) according to claim 3, characterized bythat the shear gap (30) is arranged axially between the drive-side and connection-side lamella (26, 28). [5] Fluid friction device (10) according to one of the preceding claims, characterized by that the speed-dependent axial displacement (x) of the loading element (48) is designed such that the gap width (b) increases with increasing speed (ω). [6] Fluid friction device (10) according to one of the preceding claims, characterized by that the speed-dependent axial displacement (x) is dependent on a spring characteristic of the spring element (62). [7] Fluid friction device (10) according to claim 6, characterized by that the spring characteristic is designed in such a way that the spring force (F) is quadratically proportional to the axial displacement (x). [8] Fluid friction device (10) according to claim 7, characterized bythat the spring element (62) is a disc spring (66) which is in a flat position causing the quadratic relationship between the spring force (F) and the axial displacement (x). [9] Fluid friction device (10) according to one of the preceding claims, characterized by that the spring force (F) acts on the loading element (48) over the entire axial displacement (x) of the loading element (48).

Images