Torque limiting coupling

Abstract

The invention relates to a torque limiting coupling (7) for a transmission system (1), comprising a fluid chamber (27) within a double-walled sleeve (23) to provide a frictional engagement with a shaft (11). A shear tube (37) is fluidly connected to the fluid chamber (27) and is assigned to a shear gate (45). The shear gate is fixedly connected with the shaft to open the fluid chamber (27) by shearing the shear tube (37) with the shear gate (45). At least a first shear tube (37) and a second shear tube (37) are arranged for a closure of the fluid chamber (27) and for an interaction with the shear gate (45). The shear gate (45) provides at least one shear edge (51, 53), wherein at a blocked position (38) of one shear tube (37) blocked by one shear edge (51, 53), the other shear tube (37) is positioned at an unblocked position.

Description

TECHNICAL FIELD

[0001] The present invention relates to a torque limiting coupling. The torque limiting coupling is used to connect a first rotatable shaft and a second rotatable shaft. The first rotatable shaft can be driven by a power unit, also referred to as a motor. The second shaft is connected to a load. In case of an overload, the connection of the first shaft and the second shaft slips and / or disconnects. As a torque limiting coupling, a safety coupling can be used. BACKGROUND

[0002] In particular, the torque limiting coupling comprises a release mechanism. Such a torque limiting coupling is often referred to as a safety coupling. US 10,767,711 discloses one example of such a coupling. Such a torque limiting coupling allows a slip within a predetermined range before the disengagement of the release mechanism is activated. The disclosed safety coupling comprises a drive coupling member and a driven coupling member. The driven coupling member and the drive coupling member are engaged by a frictional connection. The coupling further comprises a release element. The release element comprising a centrifugal device is configured to release the frictional connection between the drive coupling member and the driven coupling member in dependence on a rotational speed and a slip between the drive coupling member and the driven coupling member. Due to the complexity of such a mechanism, such a safety coupling is very expensive.

[0003] US 2009 / 0264253 Al discloses a clutch control system interposed between an engine and a piece of driven equipment. The clutch control system includes a clutch assembly having input and output speed sensors for providing signals corresponding to the shaft rotational speeds of the engine and driven equipment, respectively. A pressure sensor is connected to the clutch assembly and provides an output signal corresponding to the clutch pressure. A temperature sensor is also associated with the clutch assembly and provides a temperature signal corresponding to the operating temperature of the clutch assembly. Various types of sensors are also employed to sense operating conditions such as shock loading, etc. A machine control system connected to the drive equipment and an engine control module connected to the engine are also included. These signals are communicated to a clutch control unit which uses these signals to evaluate the operating conditions of the system and adjust the clutch pressure accordingly through a pressure control valve. The system provides a large amount of operating data and the clutch control unit utilizes this data to ensure optimum operation by adjusting the clutch pressure in accordance with the engine and drive equipment to minimize clutch slip and avoid or correct for shock loading situations. The slip of the clutch is determined in revolutions per minute (rpm).

[0004] WO 2007 / 085861 discloses a method of calculating the relative speed difference of an input shaft and an output shaft.

[0005] EP 3228895 A1 relates to a torque limiting coupling for a driveline. The input side of the torque limiting coupling is connectable to a power unit and the output side is connectable to a load. A first speed sensor is assigned to the input side of the torque limiting coupling and a second speed sensor is assigned to the output side of the torque limiting coupling. The sensors comprise an encoder and a detector. The encoder comprises a number of markings to provide a precise detection of slip events. Thereby, small slip events in the range of millimeters in circumferential direction can be detected. Furthermore, the direction of the slip can also be detected. SUMMARY

[0006] It is an object of the present invention to provide a torque limiting coupling with a release mechanism, wherein the costs are reduced.

[0007] It is a further object of the present invention to provide a method of using a torque limiting coupling, wherein the method allows to release the torque limiting coupling in a comfortable and useful way.

[0008] The torque limiting coupling of the present invention comprises a fluid chamber within a double-walled sleeve. By pressurizing the double-walled sleeve, a frictional engagement with a shaft can be provided. In most cases, the double-walled sleeve is arranged as a hollow sleeve arranged coaxially to the shaft, but it is also possible that the double-walled sleeve is arranged radially inside the shaft, wherein the shaft is arranged coaxially to the double-walled sleeve and radially outside the double-walled sleeve.

[0009] For pressurizing the fluid chamber, a first shear tube and a further shear tube are fluidly connected to the fluid chamber. A shear gate is fixedly connected to the shaft. The shear gate provides at least one shear edge. In a blocked position of one of the shear tubes, which is blocked by the at least one shear edge, the further shear tube is positioned in an unblocked position relative to the shear gate. Thereby, the fluid chamber can be depressurized on the unblocked shear tube. Thus, it is not necessary to shear the blocked shear tube, because at least one of the shear tubes is operable for pressurizing or depressurizing the fluid chamber. In case of a defect leading to a slip, all shear tubes can be sheared to allow an immediate depressurization of the fluid chamber, thereby quickly disconnecting the double-walled sleeve and the shaft. In case of a failure of one of the shear tubes, at least the other shear tube will be sheared for depressurization. Thus, the torque limiting coupling is very safe. By always providing an unblocked shear tube, a comfortable operation can be provided. It is also possible to depressurize the torque limiting coupling to reset the torque limiting coupling to a predetermined position. Thereby, the functionality is enhanced.

[0010] In a preferred embodiment the shear gate comprises at least one cut-out. The cut-out provides a first shear edge for releasing the torque limiting coupling in case of a slip in clockwise direction and a second shear edge for releasing the torque limiting coupling in case of a slip in counter clockwise direction. Clockwise direction and counter clockwise direction are determined by the direction of torque transmission. Each shear edge is assigned to at least one shear tube. A designated shear tube is a shear tube which is first subjected to shear in case of a slip. It is possible that one shear tube is assigned to the first and second shear edge. It is furthermore possible that a first shear tube is assigned to the first shear edge and another shear tube is assigned to the second shear edge. By the first shear edge and the second shear edge a torque limiting coupling can be provided which is sensitive to a slip in both directions. At least one shear tube is not blocked if one of the shear tubes is blocked by a shear edge.

[0011] In a further embodiment the shear gate comprises a first cut-out and a second cut-out, wherein the first cut-out is arranged for arranging a first shear tube within the cut-out and the second cut-out is arranged for arranging a second shear tube within the second cut-out. Thereby there is a clear assignment of shear tubes and shear gate.

[0012] By the arrangement of the shear tubes within the cut-out and by the dimensions of the cut-out and the position of the shear tubes within the cut-out or relative to the shear edges the torque limiting coupling can be adjusted according to the use case in a very simple manner. Furthermore an allowed slip angle can be provided without releasing the torque limiting coupling. By the release possibility of the not blocked shear tube the readjustment of the torque limiting coupling can be provided in a very comfortable manner.

[0013] Due to the fluid flow a symmetrical arrangement of the shear tubes is a preferred solution. By the adjustment of the shear gate only the torque limiting coupling can be adjusted in a very simple manner for many use cases.

[0014] In case of one cut-out and wherein at least two shear tubes are arranged, the shear tubes are preferably arranged with a distance in circumferential direction. In a preferred embodiment the shear tubes are arranged close to each other in circumferential direction to provide a maximum allowed slip angle in case of no release.

[0015] In a further embodiment the first and second shear edge of one cut-out of the shear gate are arranged in an angular position of at least 10 degrees, preferably at least 45 degrees. Most preferred is at least 90° to provide a large allowed slip angle in case of no release.

[0016] In a preferred embodiment the first and second shear pipes are connected to at least one pump connection, wherein the pump connection is arranged at an axial distance outside the axial direction of the shear gate within the thin-walled sleeve. Thus, the pump connection is always available, independent of the position of the shear gate.

[0017] In one embodiment the pump connection is arranged on the far side of the shear pipe with respect to the shear edge of the displacement gate. Thereby, in case of the unblocked position of the shear pipe, the pump connection is available.

[0018] In a preferred embodiment the torque limiting coupling comprises a sensor system to provide information about the range of degrees of a slip event and preferably the sum of the slip angle in one direction. Thus, maintenance can be triggered to reset the torque limiting coupling and to avoid a release of the torque limiting coupling.

[0019] Method of maintenance of the torque limiting coupling of the present invention, wherein for pressure adjustment or fluid exchange of the fluid chamber the unblocked shear pipe is loosened to provide a fluid connection to the fluid chamber. Preferably, a fluid connection from the fluid chamber to the pump connection is provided, wherein for providing said connection the shear pipe is loosened. It is thus important that at least one shear pipe is in the unblocked position.

[0020] Generally, there can be one separate pump connection which can be opened independent of the shear pipes. But such a pump connection would create additional costs. BRIEF DESCRIPTION OF DRAWINGS

[0021] The present invention, its objects and advantages can best be understood by reference to the following description of a preferred embodiment thereof and the accompanying drawings. The scope of the present invention is not limited by these embodiments.

[0022] Figure 1 Torque limiting coupling,

[0023] Figure 2 Torque limiting coupling, Figure 1 Expedited view of the torque limiting coupling,

[0024] Figure 3 Torque limiting coupling, Figure 1 Cross-sectional view of the torque limiting coupling,

[0025] Figure 4 Shear gate,

[0026] Figure 5 Torque limiting coupling with angularly offset shear gate,

[0027] Figure 6 Torque limiting coupling, Figure 5 Shear gate,

[0028] Figure 7 A schematic diagram of a shear gate with one slit and two shear edges.

[0029] Figure 8 Transmission system

[0030] Figure 9 Torque limiting coupling with thin-plate coupling,

[0031] Figure 10 Torque-limiting coupling between the two gear halves

[0032] Figure 11 Torque limiting coupling with flexible coupling. Detailed Implementation

[0033] Figure 1 and Figure 2 A torque-limiting coupling 7 is shown. A flange 15 is arranged on the input side for connecting a power unit 3. At the other axial end of the torque-limiting coupling 7, a flange 17 is present for connecting a load 5. In the arrangement shown, the flange 15 is fixedly connected to a shaft 11. The shaft 11 includes a friction surface 21 on its circumferential outer surface. This friction surface 21 faces a friction surface 25 of a coaxially arranged hollow shaft 13. This friction surface 25 is arranged on the inner surface of the hollow shaft 13. The hollow shaft 13 is coaxially arranged with the shaft 11. A fluid chamber 27 is provided to provide frictional engagement between the hollow shaft 13 and the shaft 11. This fluid chamber is a closed loop in the circumferential direction and extends in the axial direction. Depending on the pressure in the fluid chamber 27, the fluid chamber expands in the radial direction. Therefore, the frictional engagement between the friction surface 21 of the shaft and the friction surface 25 of the hollow shaft 13 is adjustable. In this embodiment, the fluid chamber 27 is arranged within the hollow shaft 13. However, such fluid chambers can also be arranged in a radially inwardly arranged shaft, as disclosed in DE 40 28 158 A1.

[0034] In the shown embodiment, the fluid chamber is part of the double-walled sleeve 23. For pressurization, a pump connection seat 41 and shear-off tubes are provided. For pressurization, a pump is connected with the pump connection seat. The shear-off tubes 37 are screwed into the double-walled sleeve 23 in a predetermined position for pressurization. Thus, a direct fluid connection of the fluid chamber 27 with the outside is closed. However, a fluid connection with the pump is still available. Thus, a depressurization and a pressurization can be carried out. After pressurization, the shear-off tubes are screwed into an end position, in which the connection with the pump connection seat 41 is closed. The bearing of the hollow shaft 13 on the shaft 11 is provided by two bearings 29. The bearings are sealed by a seal 31, and the lubrication of the bearings can be carried out by a lubrication connector 39. On one side of the flange 17, a cap 33 is arranged to enclose the hollow shaft 13. For interaction with the shear-off tubes 37, a shear-off gate 45 is arranged coaxially to the double-walled sleeve 23 at the axial height of the shear-off tubes. The shear-off gate 45 and the shear-off tubes 37 provide a release mechanism 35. Here, the shear-off gate is fixedly connected to the shaft 11 of the flange 15 by a screw 46. The shear-off gate comprises at least one cutout, as shown in Figure 7 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 3 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 4 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 5 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 6 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figures 3 to 6 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 1 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49.

[0035] In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 3 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 4 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. Figure 3 In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49. In the shown embodiment, the shear-off gate comprises a first cutout 47 and a second cutout 49.

[0036] In case of a serious defect, the first shear tube that arrives at the blocking position is sheared first. Thereafter, the second shear tube is sheared. If one of the shear tubes is defective and no fluid can flow through the defective shear tube, the disconnection is provided by the other shear tube.

[0037] Figure 5 and Figure 6 Embodiments are disclosed with a shear gate 45 with a first cut 47 and a second cut 49 that extend equally long in the circumferential direction. In each cut a shear tube is arranged. By the position of the first cut 47 and the second cut 49 relative to the position of the shear of the pipe 37, it is achieved that in the blocking position of the shear tube in the first cut, the shear tube in the second cut is in the non-blocking position and vice versa.

[0038] The shear tube is opened by shearing the shear tube with the first shear edge 51 or the second shear edge 53 according to the direction of the slip. The shear edges 51 ', 53'shear the shear tube at a later point in time.

[0039] The pump connection is arranged in the cut of the shear gate on the side further away from the shear edge. It is also possible to arrange the pump connection at an axial distance from the shear tube and wherein the pump connection 41 is outside the axial extent of the shear gate 45.

[0040] According to Figure 7 Embodiments are disclosed with a shear gate with only one cut. With such a shear gate, it is possible to provide a large slip angle without disengagement of the torque limiting coupling. In order to provide a large slip area in which the torque limiting coupling is not engaged, the shear tube must be arranged at a distance of only a few degrees in the circumferential direction.

[0041] If the slip will only occur in two directions, the shear tube will be positioned in the middle of the cut 47, 49 as a starting position. In case of a slip in only one direction, the shear tube is positioned at the maximum distance from the shear edge as a starting position.

[0042] Figure 8A drive train 1 comprising a torque limiting coupling 7 is disclosed. The drive train 1 comprises a power unit 3 for rotationally driving an input shaft 4. The input shaft 4 is connected with the torque limiting coupling 7. By means of the torque limiting coupling 7, torque can be transmitted to an output shaft 8. The output shaft 8 is connected with a load 5. In this embodiment, the torque limiting coupling 7 comprises a sensor system 61. An encoder 67 is arranged on the input side. This encoder 67 is a pulse generator. This encoder 67 is read out by a detector 65. The signal read out by the detector 65 on the input side is transmitted to a controller 100. In the shown embodiment, there is a data line between the detector 65 on the input side and the controller 100, but a wireless connection is also possible. The encoder 67 and the detector 65 on the input side are part of the sensor 63 on the input side. Another encoder 77 is arranged on the output side of the torque limiting coupling 7. A detector 75 is assigned to this encoder 77 on the output side. The encoder 77 and the detector 75 are components of the sensor 73 on the output side of the torque limiting coupling 7 for measuring the rotational speed of the output shaft 8. The signal of the sensor 73 on the output side is transmitted to the controller 100.

[0043] The controller 100 determines the angular position of the input shaft 4 of the torque limiting coupling 7 on the basis of the signal of the first sensor 63. Furthermore, the controller 100 determines the angular position of the output shaft 8 of the torque limiting coupling 7. The angular positions of the input shaft 4 and the output shaft 8 of the torque limiting coupling 7 are determined at equal moments in time. In order to determine the slip of the torque limiting coupling 7, the difference between the determined angular position detected by the sensor 63 on the input side and the determined angular position detected by the sensor 73 on the output side is determined at a certain moment in time. The determined difference corresponds to the slip within the torque limiting coupling 7. By storing the slip angle and the slip direction as a function of time, slip events and slip duration can be analyzed. Small slip events can be determined as well as long slip events. On the basis of the determined slip events, frequency and duration, a trigger signal can be emitted. On the basis of the determined slip events, in particular on the basis of the sum of the slip angles in one direction, a maintenance interval can be determined to avoid release of the torque limiting coupling 7. Furthermore, the torque provided by the power unit 3 can be reduced to avoid further slip, or the load 5 can be adjusted to avoid further slip. In particular, this can be done as long as a reset of the torque limiting coupling has not yet occurred to avoid release of the torque limiting coupling 7.

[0044] Figure 9 The use of a torque limiting coupling 7 in series with a lamella coupling 111 is disclosed. In Figure 10 The arrangement of a torque limiting coupling 7 between two gear coupling halves 131 is shown. Figure 11 The torque limiting coupling 7 is shown in series with a flexible coupling 121.

[0045] Reference list

[0046]

[0047]

Claims

1. A torque limiting coupling (7) for a transmission system (1), the torque limiting coupling (7) comprising a fluid chamber (27) located within a double-walled sleeve (23) to provide frictional engagement with a shaft (11), in, The shear tube (37) is fluidly connected to the fluid chamber (27) and the shear tube (37) is assigned to the shear gate (45). The shear gate is fixedly connected to the shaft to open the fluid chamber (27) by cutting the shear tube (37) with the shear gate (45). Its features are, At least a first shear tube (37) and a second shear tube (37) are arranged to close the fluid chamber (27) and to interact with the shear gate (45), and the shear gate (45) provides at least one shear edge (51, 53). In one of the shearing tubes (37), at a stopped position (38) where it is stopped by a shearing edge (51, 53), another shearing tube (37) is positioned at an unstoppable position relative to the shearing gate (45). The first shear tube (37) and the second shear tube (37) are connected to at least one pump connector (41), wherein the pump connector (41) is arranged axially outside the shear gate (45) at an axial distance within the double-walled sleeve (23).

2. The torque limiting coupling (7) according to claim 1, Its features are, The shear gate (45) includes at least one cut (47, 49), the at least one cut (47, 49) providing: A first shearing edge (51) is used to release the torque-limiting coupling upon sliding in a first clockwise direction; and A left shearing edge (53) is used to release the torque-limiting coupling upon sliding in a second counterclockwise direction. Each cut edge (51, 53) is assigned to at least one cut tube (37).

3. The torque limiting coupling according to claim 2, Its features are, The shear gate (45) includes a first cut (47) and a second cut (49), wherein the first cut (47) is configured to arrange the first shear tube (37) within the first cut (47), and the second cut (49) is configured to arrange the second shear tube (37) within the second cut (49).

4. The torque limiting coupling according to claim 3, Its features are, The first cut (47) and the second cut (49) of the shear gate (45) are arranged asymmetrically with respect to the shear tube (37) arranged in the cuts (47, 49).

5. The torque limiting coupling according to any one of claims 2 to 4, Its features are, The cuts (47, 49) of the shear gate (45) have the same extent of extension in the circumferential direction.

6. The torque limiting coupling according to any one of claims 3 to 4, Its features are, Compared to the first cut (47), the second cut (49) of the shear gate (45) has a greater extension range in the circumferential direction.

7. The torque limiting coupling according to any one of claims 1 to 4, Its features are, The first shear tube (37) and the second shear tube (37) are arranged in a cut (47) of the shear gate, wherein the first shear tube (37) and the second shear tube (37) are arranged separately in the circumferential direction.

8. The torque limiting coupling according to any one of claims 1 to 4, Its features are, The first shearing edge (51) and the second shearing edge (53) of a cut (47, 49) of the shear gate (45) are arranged at a circumferential distance of at least 10 degrees.

9. The torque limiting coupling according to claim 8, Its features are, The first shearing edge (51) and the second shearing edge (53) of a cut (47, 49) of the shear gate (45) are arranged at a circumferential distance of at least 45 degrees.

10. The torque limiting coupling according to any one of claims 1 to 4, Its features are, The pump connector (41) is located on the far side of the shear tube relative to the shearing edges (51, 53) of the cut (47, 49) of the shear gate (45).

11. The torque limiting coupling according to any one of claims 1 to 4, Its features are, The coupling includes a sensor system (61) to provide information on the degree range of slip events.

12. The torque limiting coupling according to claim 11, Its features are, The coupling includes a sensor system (61) to provide the sum of the slip angles in each circumferential direction.

13. A transmission system comprising a power unit (3), a load (5), and a torque limiting coupling (7) as described in any of the preceding claims.

14. The transmission system according to claim 13, Its features are, A controller (100) is assigned to the transmission system (1), wherein the load (5) and the power unit (3) are controlled taking into account the determined slippage of the torque limiting coupling (7).

15. A method for maintaining a torque-limiting coupling (7) according to any one of claims 1 to 12, wherein, To adjust fluid pressure or change fluid, loosen the unblocked cut tube (37) to provide fluid connection to the fluid chamber (27).

16. The maintenance method for the torque limiting coupling (7) according to claim 15, wherein, To adjust fluid pressure or change fluid, loosen the unblocked cut-off tube (37) to provide a fluid connection from the pump connector (41) to the fluid chamber (27).

17. A method for using a torque-limiting coupling (3) in a transmission system according to claim 14, Its features are, The controller (100) calculates the slip angle position, and if a predetermined maximum slip angle is reached, the controller (100) triggers a signal that requires a reset.

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