Dynamic clamping system for endless pull cords

Abstract

Dynamic tensioning system (1) for continuous tensioning device (2) comprising an actuator (3) and a first deflection element (4), wherein the actuator (3) interacts with the first deflection element (4) and wherein the actuator (3) enables the first deflection element (4) to be moved relative to the continuous tensioning device (2) in order to change the preload of the continuous tensioning device (2), characterized in that the tensioning system (1) has a second deflection element (5), wherein the second deflection element (5) engages with the continuous tensioning device (2) and wherein the second deflection element (5) is configured to interact with the first deflection element (4) and the continuous tensioning device (2) in the manner of a pulley system.

Description

[0001] The present invention relates to a dynamic tensioning system for endless traction means according to the preamble of independent claim 1.

[0002] A generic dynamic tensioning system for endless traction means comprises an actuator and a first deflection element, wherein the actuator interacts with the first deflection element and wherein the actuator enables a delivery of the first deflection element relative to the endless traction means in order to change the pretension of the endless traction means.

[0003] Endless traction systems are used to transmit rotary drive forces, especially when a certain distance must be overcome between the input and output. Ropes, chains, and belts of various types can be used as endless traction devices and thus for power transmission. Depending on the application and area of ​​use, endless traction systems require tensioning devices to maintain the traction force required for power transmission between the endless traction device and the traction sheave in the relevant operating ranges or to adjust it to a predefined value.

[0004] Especially with high loads and high precision requirements, dynamic maintenance of the required pretension force throughout the entire tension system is necessary to prevent the endless tension member from slipping or jumping off the traction sheave. The demands on the tensioning system also increase with the length of the endless tension system. Ensuring the required pretension often requires large travel distances for the actuator used for tensioning or the use of multiple actuators, which increases the complexity of the tensioning system.

[0005] From DE 100 13 340 A1, a dynamic tensioning system according to the preamble of independent claim 1 is already known. A belt grinding machine is described whose grinding belt is designed as an endless traction device, wherein the belt tension is regulated and adjusted by means of an actuator such that a predefined pressure force is applied to a contact roller as constantly as possible.

[0006] However, the described clamping system is not ideally suited for the use of long endless tensioning devices whose preload requires dynamic control. Firstly, the use of long endless tensioning devices increases the travel distance required for the clamping system to maintain the required preload, which in turn impedes dynamic control. Secondly, longer travel distances result in a larger installation space requirement for the actuator.

[0007] Further known prior art is formed by the document FR 698 128 A, which shows a V-belt drive in which two deflection elements are arranged in such a way that the wrap angle of the endless traction means is significantly increased.

[0008] In order to overcome the above-mentioned disadvantages, the present invention has set itself the task of providing a dynamic tensioning system for endless traction devices which increases the dynamics of the tensioning force control while maintaining the same actuator size.

[0009] The problem is solved by the features of independent claim 1.

[0010] Accordingly, the object is achieved according to the invention if the tensioning system has a second deflection element, wherein the second deflection element engages with the endless traction means and wherein the second deflection element is designed to interact with the first deflection element and the endless traction means in the manner of a pulley.

[0011] Advantageous embodiments of the present invention are the subject of the subclaims.

[0012] According to an advantageous embodiment of the present invention, the first deflection element comprises a first roller and a second roller, wherein the first roller and the second roller are arranged such that the endless traction means is deflected by the two rollers one after the other. A particularly simple and compact design is possible if the two rollers are arranged essentially parallel to one another, which means that the planes which lie in the normal direction to the respective axis of rotation run essentially parallel to one another. In the present arrangement, essentially parallel means that the angle between the two planes does not exceed a value of 10°, advantageously does not exceed a value of 5° and particularly advantageously lies within the usual positional tolerance when aligning the two rollers to one another.

[0013] A simple and compact design is also possible if the axes of rotation of the two rollers are aligned essentially coaxially with each other. In this embodiment, essentially coaxial means that the planes run essentially parallel to each other in the normal direction to the axes of rotation, and that the distance between the axes of rotation is not greater than the width of one roller, preferably not wider than half the width of one roller. Particularly preferably, the axes of both rollers are spaced apart from each other at a distance that does not exceed the usual tolerance during installation of the rollers.

[0014] To ensure a simple and compact design of the first deflection element, it is advantageous if the first and second rollers are the same size. However, it is also conceivable for both rollers to be the same width but have different diameters, or for both rollers to have the same diameter despite differing widths. Preferably, however, both rollers have the same technical dimensions and differ only in manufacturing-related deviations.

[0015] In certain applications, however, it may also be conceivable for the two rollers to be at an angle to each other, meaning their rotational axes are not coaxial. This can be necessary, for example, in tight installation spaces or to achieve better guidance of the endless traction device.

[0016] According to a further advantageous embodiment of the present invention, the second deflection element comprises a third roller.

[0017] According to a particularly advantageous embodiment of the present invention, the second deflection element is arranged such that the endless traction means is deflected by the second deflection element between the deflections by the first and second rollers. The first deflection element and the second deflection element therefore interact like a pulley block, with one of the two deflection elements forming the loose roller required for a pulley block and the other deflection element forming the fixed roller. The third roller can be arranged essentially parallel to the first and second rollers, but to ensure the pulley block principle, the third roller or the axis of rotation of the third roller is in any case arranged at a certain distance from the axis of rotation of the rollers of the first deflection element. It is conceivable that the third roller is not aligned parallel to the first two rollers.Preferably, however, the plane which lies in the normal direction to the axis of rotation of the third roller and passes through the center of the third roller lies between the first and the second roller or intersects one of the two rollers.

[0018] According to a further advantageous embodiment of the present invention, the first roller has a first guide and the second roller has a second guide to prevent the endless traction means from coming into contact with itself. Of course, the third roller can also have a guide. The guides can, for example, take the form of recesses or grooves running circumferentially around the rollers, in order to prevent the endless traction means from slipping off a roller and to prevent the endless traction means from coming into contact with itself. In principle, however, any other conceivable guide design known from the prior art can also be used. The two rollers are preferably rotatable independently of one another.

[0019] According to a particularly advantageous embodiment of the present invention, the actuator comprises a cylinder and a piston rod. However, in principle, any type of actuator suitable for applying the necessary travel distance and force to move the first deflection element relative to the endless traction device and thereby pretension the endless traction device can be used.

[0020] According to another particularly advantageous embodiment of the present invention, the actuator comprises a controllable hydraulic cylinder. The piston rod can engage directly with the first deflection element, whereby the movement of the piston rod is transmitted directly to the deflection element. It is of course also conceivable for the piston rod and the first deflection element to interact via a kinematic system, and the movement and force of the piston rod are translated. The travel distance and force that the piston rod exerts on the first deflection element and thus on the endless traction device can be controlled, for example, via a hydraulic system. It is clear that the actuator can also comprise a pneumatic cylinder, and in this case, a pneumatic system is necessary to control the force and travel distance.

[0021] According to a further advantageous embodiment of the present invention, the first deflection element interacts with the actuator in such a way that the first deflection element is moved in the working direction of the actuator in order to change the pretension of the endless traction device. In other words, the first deflection element is preferably moved along the movement of the piston rod towards the endless traction device or away from the endless traction device in order to change the pretension of the endless traction device. Due to the alignment of the deflection elements in interaction with the endless traction device, which acts as a pulley, an increased force is required to pretension the actuator by the actuator compared to the tensioning devices described in the prior art. However, the necessary travel path is shortened - in a way reversing the idea of ​​the pulley principle. This has the advantage of increased dynamics of the pretensioning system, especially with long endless traction devices.At the same time, a shortened travel path also means that less installation space is required for the design of the preload system.

[0022] It is inherent in the present invention that the pulley principle can be modified or expanded as desired to shorten the actuator's travel path. For example, to further reduce the travel path required to pre-tension the endless traction device, it is conceivable for the first deflection element to comprise an additional pulley, and for the second deflection element to comprise an additional pulley, so that an additional pair of fixed and loose pulleys is created by means of an additional loop of the endless traction device.

[0023] The second deflection element can be stationary, apart from its freedom of rotation. However, it is conceivable that the actuator is designed in such a way and that the second deflection element interacts with the actuator in such a way that the second deflection element moves in a direction opposite to the first deflection element and thereby also contributes to the pretension of the endless traction device. It is also conceivable that the first deflection element is fixed, i.e. represents the fixed roller of a pulley system, and that the second deflection element can be adjusted relative to the endless traction device by the actuator in order to change the pretension of the endless traction device. In other words, a change in the pretension of the endless traction device can always be generated when the two deflection elements are not moved in the same direction over the same travel distance.

[0024] According to a further advantageous embodiment of the present invention, the second deflection element is arranged in line with the working direction of the actuator. In order to achieve the most compact design possible for the pretensioning system, it is advantageous if the second deflection element is provided as close to the actuator as possible. The second deflection element can be fixedly and immovably arranged on the actuator, but it can also be attached in some other way. As already described above, the second deflection element can also be designed such that it is moved by the actuator relative to the endless traction means in order to change the pretension of the endless traction means. In any case, the second deflection element is preferably arranged in line, i.e., flush, with the working direction. This means that the line of the working direction intersects the second deflection element.However, for space reasons, it may also be necessary to arrange the second deflection element at a distance from the line of the working direction of the actuator.

[0025] According to an advantageous embodiment of the present invention, the tensioning system is designed for an endless traction device embodied as a steel cable. However, the dynamic tensioning system according to the invention can also be easily applied to belts, chains, bands, or other endless traction devices known from the prior art.

[0026] An embodiment of the present invention is explained in more detail below with reference to drawings.

[0027] In the following explanations, identical parts are designated by identical reference numerals. If a figure contains reference numerals that are not explained in detail in the corresponding figure description, reference is made to the preceding or subsequent figure descriptions. Fig. 1a shows a schematic representation of the interaction of a dynamic tensioning system according to the invention with an endless tensioning means, Fig. 1b shows a side view of the Fig. 1b and Fig. 2 shows an embodiment of a dynamic clamping system according to the invention.

[0028] Fig. 1a schematically shows the interaction of a dynamic tensioning system 1 according to the invention with an endless tensioning means 2. The endless tensioning means 2 is guided and held in position by the two lower tensioning rollers in the illustration, one of which is designed as a drive roller, and the first deflection element 4 assigned to the dynamic tensioning system 1. The dynamic tensioning system 1 comprises an actuator 3, which in the present embodiment has a cylinder 11 and a piston rod 12, wherein the cylinder 11 is designed as a hydraulic cylinder 13. The actuator 3 can be controlled by a hydraulic control system (not shown). The first deflection element 4 is arranged on the piston 12 of the actuator 3 and can thus be moved directly by the actuator 3. The working direction 14 is indicated by arrows.The first deflection element 4 is also moved relative to the endless traction element 2 along this direction, allowing the preload of the endless traction element 2 to be increased or decreased. It can be clearly seen that the second deflection element 5 is attached to the actuator and, like the first deflection element 4, is aligned with the working direction 14 of the actuator.

[0029] In summary of Fig. 1a with Fig. 1b and with Fig. 2, which shows an embodiment of a dynamic tensioning system 1 according to the invention, it is also clear that in the illustrated embodiment, the first deflection element 4 comprises two rollers 6, 7, which are of equal size and whose axes of rotation 15, 16 are aligned coaxially with one another. In addition, the first roller 6 and the second roller 7 are independently rotatable. The third roller 8 is arranged such that its axis of rotation 17 is parallel to and at a certain distance from the axes of rotation 15, 16 of the first roller 6 and the second roller 7. In addition, the center plane of the third roller 8, which is aligned in the normal direction to the axis of rotation 17, runs between the first two rollers 6, 7. Clearly visible in Fig. 1b also the guides 9, 10 of the first and second rollers 6, 7, which are designed as circumferential grooves, whereby the guide of the third roller 8 is designed in the same way.

[0030] In Fig. 1b, the endless traction device 2, which can be a steel cable, is represented by a dashed line, with the arrows indicating the direction of movement of the respective strand of the endless traction device 2. It should be noted at this point that the endless traction device 2 can, in principle, also move in the other direction, in which case all arrows would point in the opposite direction. The endless traction device 2 is pulled by the tension pulley at the bottom right in the Fig. to the dynamic tensioning system 1. Within the dynamic tensioning system 1, the endless traction means 2 is deflected from the first roller 6 to the third roller 8 and from the third roller 8 to the second roller 7. Due to this special arrangement, the three rollers 6, 7, 8 act together as a pulley system, with the first deflection element 4 comprising the first roller 6 and the second roller 7 forming the so-called loose roller and the second deflection element 5 comprising the third roller 8 forming the fixed roller. If the endless traction means 2 is to be pre-tensioned more strongly by the actuator 3, the piston rod 12 and with it the first deflection element 4 in the illustration in Fig. 1a is moved upwards. Compared to a conventional clamping system without a second deflection element 5, which interacts with the first deflection element 4 like a pulley, only half the travel distance of the piston rod 12 is required for the same change in preload, whereby, of course, the actuator must apply correspondingly more force.

[0031] Fig. 1a further shows that the wrap angle α of the second rollers 7 is less than 90°. However, it is also possible that the angle is exactly 90° and that the wrap angles of the first roller 6 and the second roller 7 are each 90°, so that the strands are aligned with each other during feeding and removal from the tensioning system 1. List of reference symbols: 1 clamping system 2 endless traction devices 3 Actuator 4 first deflection element 5 second deflection element 6 first role 7 second role 8 third role 9 first lead 10 second lead 11 cylinders 12 Piston rod 13 hydraulic cylinders 14 Working direction 15 Rotation axis of the first roller 16 Rotation axis of the second roller 17 Rotation axis of the third roller α Wrap angle

Claims

[1] Dynamic tensioning system (1) for endless traction means (2) comprising an actuator (3) and a first deflection element (4), wherein the actuator (3) cooperates with the first deflection element (4) and wherein the actuator (3) enables a delivery of the first deflection element (4) relative to the endless traction means (2) in order to change the pretension of the endless traction means (2), characterized by that the tensioning system (1) has a second deflection element (5), wherein the second deflection element (5) is in engagement with the endless traction means (2) and wherein the second deflection element (5) is designed to interact with the first deflection element (4) and the endless traction means (2) in the manner of a pulley. [2] Dynamic clamping system (1) according to claim 1, characterized bythat the first deflection element (4) comprises a first roller (6) and a second roller (7), wherein the first roller (6) and the second roller (7) are arranged such that the endless traction means (2) is deflected one after the other by the two rollers (6, 7). [3] Dynamic clamping system (1) according to one of claims 1 or 2, characterized by that the second deflection element (5) comprises a third roller (8). [4] Dynamic clamping system (1) according to one of claims 2 or 3, characterized by that the second deflection element (5) is arranged such that the endless traction means (2) is deflected by the second deflection element (5) between the deflections by the first roller (6) and the second roller (7). [5] Dynamic clamping system (1) according to one of claims 1 to 4, characterized by that the first roller (6) has a first guide (9) and the second roller (7) has a second guide (10) to prevent contact of the endless traction means (2) with itself. [6] Dynamic clamping system (1) according to one of claims 1 to 5, characterized by that the actuator (3) comprises a cylinder (11) and a piston rod (12). [7] Dynamic clamping system (1) according to claim 6, characterized by that the actuator (3) comprises an adjustable hydraulic cylinder (13). [8] Dynamic clamping system (1) according to one of claims 1 to 7, characterized by that the first deflection element (4) interacts with the actuator (3) in such a way that the first deflection element (4) is moved in the working direction of the actuator (3) in order to change the pretension of the endless traction means (2). [9] Dynamic clamping system (1) according to one of claims 1 to 8, characterized by that the second deflection element (5) is arranged on a line with the working direction (14) of the actuator (3). [10] Dynamic clamping system (1) according to one of claims 2 to 9, characterized bythat the first roller (6) and the second roller (7) each have an axis of rotation, wherein the axes of rotation are aligned substantially coaxially with one another.

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