Dynamic tensioning system for endless traction devices

Abstract

To provide a dynamic tensioning system for an endless traction device.SOLUTION: A tensioning system for an endless traction device includes an actuator and a first deflection element. The actuator interacts with the first deflection element, and the actuator enables the first deflection element to be moved relative to the endless traction device so as to change the pre-tension of the endless traction device. The tensioning system includes a second deflection element. The second deflection element is engaged with the endless traction device, and the second deflection element is configured to interact with the first deflection element and the endless traction device in the manner of a pulley.SELECTED DRAWING: Figure 1a

Description

Technical Field

[0001] The present invention relates to a dynamic tension applying system for an endless traction device as described in the preamble of independent claim 1.

Background Art

[0002] A general dynamic tension applying system for an endless traction device includes an actuator and a first deflecting element, the actuator interacts with the first deflecting element, and in order to change the pre-tension of the endless traction device, the actuator can move the first deflecting element relative to the endless traction device.

[0003] An endless traction system is used to transmit a rotational driving force, especially when it is necessary to overcome a certain distance between a driving part and an output part. Ropes, chains, and belts of various shapes can be used as endless traction devices and thus for power transmission. Depending on the application and field of use, a tension applying device is required for the endless traction system to maintain the traction force required for power transmission between the endless traction device and the driving pulley within the relevant operating range or to set it to a predetermined value.

[0004] In particular, when high loads and high precision are required, it is necessary to dynamically maintain the required pre-tension throughout the traction system so that the endless traction device does not slip out of or jump out of the traction sheave. As the length of the endless traction system increases, the requirements for the tension applying system also increase. To ensure the required pre-tension, it is often necessary to move the actuator used for tension application over a long distance or to use a plurality of actuators, which increases the complexity of the tension applying system.

[0005] A dynamic tensioning system using a preamble according to independent claim 1 is known from Patent Document 1. In a belt polishing machine, the polishing belt is configured as an endless traction device, and the belt tension is adjusted and set by an actuator so that a predetermined pressing force is applied to the contact sheave as constant as possible.

[0006] However, the tensioning system described is not ideal for use with long endless traction devices that require dynamic control of pre-tension. On the one hand, using a long endless traction device increases the travel path of the tensioning system required to maintain the required pre-tension, which is contrary to dynamic control. On the other hand, a longer travel path results in increased installation space requirements for the actuator. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] German Patent Application Publication No. 100 13 340(A1) Specification [Overview of the project] [Problems that the invention aims to solve]

[0008] To overcome the above drawbacks, the present invention is based on the objective of providing a dynamic tensioning system for an endless traction device that improves the dynamics of tension control while maintaining the same actuator size. [Means for solving the problem]

[0009] This objective is achieved by the features of independent claim 1.

[0010] According to this, this objective is achieved by the present invention, in which the tensioning system comprises a second deflection element, the second deflection element engages with an endless traction device, and the second deflection element is configured to interact with the first deflection element and the endless traction device like a pulley.

[0011] Advantageous embodiments of the present invention are subject to the dependent claims.

[0012] According to an advantageous embodiment of the present invention, the first deflection element comprises a first sheave and a second sheave, the first and second sheaves arranged such that the endless traction device is continuously deflected by the two sheaves. A particularly simple and compact design is possible when the two sheaves are arranged substantially parallel to each other and the planes normal to their respective axes of rotation extend substantially parallel to each other. In this arrangement, substantially parallel means that the angle between the two planes does not exceed 10°, preferably not exceeding 5°, and particularly advantageously is within the normal positional tolerance when aligning the two sheaves relative to each other.

[0013] A simple and compact design is possible even when the axes of rotation of two sheaves are aligned so as to be substantially coaxial with each other. In this embodiment, substantially coaxial means that planes normal to the axes of rotation extend substantially parallel to each other, the distance between the axes of rotation is less than or equal to the width of the sheave, preferably less than or equal to half the width of the sheave, and particularly preferably the axes of both sheaves are spaced apart by a distance that does not exceed the general tolerance when installing the sheaves.

[0014] For a simple and compact design of the first deflection element, it is advantageous to make the first and second sheaves the same size. However, it is also possible for both sheaves to have the same width but different diameters, or for the two sheaves to have the same diameter but different widths. However, it is preferable that both sheaves have the same technical dimensions, with only manufacturing-related deviations differing.

[0015] However, in certain applications, the two sheaves may be angled relative to each other, meaning their axes of rotation are not coaxial. This is intended, for example, when installation space is limited or to achieve better guidance in an endless traction device.

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

[0017] According to a particularly advantageous embodiment of the present invention, the second deflection element is positioned such that the endless traction device is deflected by the second deflection element between the deflection by the first and second sheaves. Thus, the first and second deflection elements interact like a pulley, with one of the two deflection elements forming a loose sheave necessary for a pulley, and the other deflection element forming a fixed sheave. The third sheave can be positioned substantially parallel to the first and second sheaves, but to ensure the pulley principle, the third sheave or the axis of rotation of the third sheave is always positioned at a certain distance from the axis of rotation of the first deflection element's sheave. It is also conceivable that the third sheave be aligned so as not to be parallel to the first two sheaves. However, it is preferable that the plane that lies normal to the axis of rotation of the third sheave and passes through the center of the third sheave lies between the first and second sheaves or intersects with one of the two sheaves.

[0018] According to a more advantageous embodiment of the present invention, the endless traction device is prevented from coming into contact with itself by having a first sheave with a first guide and a second sheave with a second guide. Of course, a third sheave may also be provided with a guide. The guide may be present, for example, in the form of a recess or groove extending circumferentially around the sheave to firstly prevent the endless traction device from slipping off the sheave and secondly prevent the endless traction device from coming into contact with itself. However, in principle, any other conceivable configuration of guides known from the prior art may also be used. The two sheaves may preferably be able to rotate independently of each other.

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

[0020] According to a more particularly advantageous embodiment of the present invention, the actuator includes a controllable hydraulic cylinder. The piston rod can directly engage with a first deflection element, thereby directly transmitting the motion of the piston rod to the deflection element. Of course, it is also conceivable that the piston rod and the first deflection element interact via a kinematic system to transmit the motion and force of the piston rod. The path of movement and force exerted by the piston rod on the first deflection element and, by extension, the endless traction device can be controlled, for example, using a hydraulic system. It is obvious that the actuator may also include a pneumatic cylinder, in which case a pneumatic system is required to control the force and path of movement.

[0021] According to a more advantageous embodiment of the present invention, the first deflection element interacts with the actuator such that the first deflection element moves in the direction of motion of the actuator in order to change the pre-tension of the endless traction device. In other words, to change the pre-tension of the endless traction device, it is preferable that the first deflection element moves toward the endless traction device along the movement of the piston rod or moves toward the endless traction device. The alignment of the deflection element interacting with the endless traction device and functioning as a pulley increases the force required to impart pre-tension to the actuator compared to the tensioning devices described in the prior art, but instead, the required travel path is shortened by reversing the concept of the pulley principle. This has the advantage of improving the dynamics of the pre-tensioning system, especially in the case of long endless traction devices. At the same time, the shortening of the travel path also means that less installation space is required to configure the pre-tensioning system.

[0022] The essence of the present invention is that the principle of the pulley can be modified or extended as needed to shorten the travel path of the actuator. To further shorten the travel path required to pre-tension the endless traction device, it is conceivable that the first deflection element may be further equipped with another sheave and the second deflection element with yet another sheave, such that further loops of the endless traction device create further pairs of fixed and loose sheaves.

[0023] The second deflection element can be configured to be fixed, separate from its rotational degrees of freedom. However, if the actuator is configured in this way, the second deflection element may interact with the actuator, causing it to move in the opposite direction to the first deflection element, thereby contributing to the pre-tension of the endless traction device. Alternatively, the first deflection element may be fixed, i.e., representing the fixed sheave of the pulley, and the second deflection element may be advanced relative to the endless traction device by the actuator in order to change the pre-tension of the endless traction device. In other words, if the two deflection elements are not moved in the same direction along the same path, a change in the pre-tension of the endless traction device can always be generated.

[0024] According to a more advantageous embodiment of the present invention, the second deflection element is positioned in a straight line with the direction of motion of the actuator. For the most compact pre-tensioning system possible, it is advantageous to position the second deflection element as close to the actuator as possible. The second deflection element can be fixed to the actuator and positioned so as not to move, but it can also be mounted elsewhere. As already described above, the second deflection element can also be configured to be moved relative to the endless traction device by the actuator in order to change the pre-tension of the endless traction device. Preferably, the second deflection element is positioned in a straight line with the direction of motion, i.e., aligned. This means that the line of motion intersects the second deflection element. However, for installation space reasons, it may be necessary to position the second deflection element away from the line of motion of the actuator.

[0025] According to an advantageous embodiment of the present invention, the tensioning system is configured for an endless traction device configured as a steel cable. However, the dynamic tensioning system according to the present invention can be used without problems also for belts, chains, straps, or other endless traction devices known from the prior art.

[0026] [[ID=⑤]] One embodiment of the present invention will be described in more detail below with reference to the drawings.

[0027] In the following description, like reference numerals are assigned to like components. If the drawings include reference numerals that are not described in detail in the description of the associated drawings, the description of the previous or subsequent drawings is referred to.

Brief Description of the Drawings

[0028] [Figure 1a] It is a schematic diagram of the interaction of the dynamic tensioning system according to the present invention with an endless traction device. [Figure 1b] It is a side view of FIG. 1a. [Figure 2] It is a diagram showing an embodiment of the dynamic tensioning system according to the present invention.

Mode for Carrying Out the Invention

[0029] Figure 1a schematically illustrates the interaction of the dynamic tensioning system 1 according to the present invention with the endless traction device 2. The endless traction device 2 is guided and held in place by two tensioning sheaves (one of which is configured as a drive sheave) shown at the bottom of the figure and a first deflection element 4 associated with the dynamic tensioning system 1. In this embodiment, the dynamic tensioning system 1 comprises an actuator 3 including a cylinder 11 and a piston rod 12, the cylinder 11 being configured as a hydraulic cylinder 13. The actuator 3 can be controlled by a hydraulic control system (not shown). The first deflection element 4 is positioned on the piston 12 of the actuator 3 and can therefore be moved directly by the actuator 3. The direction of motion 14 is indicated by an arrow. The first deflection element 4 also moves relative to the endless traction device 2 along this direction, thereby increasing or decreasing the pre-tension of the endless traction device 2. It is evident that a second deflection element 5 is attached to the actuator and, like the first deflection element 4, is positioned in alignment with the direction of motion 14 of the actuator.

[0030] Figures 1a and 1b provide an overview, and Figure 2 shows an embodiment of the dynamic tensioning system 1 according to the present invention. It is also evident that the first deflection element 4 of the illustrated embodiment comprises two sheaves 6 and 7, which are formed to be the same size and whose rotation axes 15 and 16 are aligned to be coaxial with each other. Furthermore, the first sheave 6 and the second sheave 7 can rotate independently of each other. The third sheave 8 is positioned such that its rotation axis 17 is parallel to and at a certain distance from the rotation axes 15 and 16 of the first sheave 6 and the second sheave 7. Furthermore, the central plane of the third sheave 8, which is aligned normal to the rotation axis 17, extends between the first two sheaves 6 and 7. Guides 9 and 10 of the first and second sheaves 6 and 7, which are configured as circumferential grooves, are also clearly visible in Figure 1b, and the guide of the third sheave 8 is similarly configured.

[0031] In Figure 1b, an endless traction device 2, which may be a steel cable, is shown by a dashed line, and the arrows indicate the direction of motion of each strand of the endless traction device 2. At this point, it should be noted that the endless traction device 2 can, in principle, also move in the opposite direction, in which case all the arrows point in the opposite direction. The endless traction device 2 is deflected from the tension-applying sheave in the lower right of Figure 1a to the dynamic tension-applying system 1. Within the dynamic tension-applying system 1, the endless traction device 2 is deflected from the first sheave 6 to the third sheave 8, and from the third sheave 8 to the second sheave 7. In this special arrangement, the three sheaves 6, 7, and 8 together function as a pulley, with the first deflection element 4, including the first sheave 6 and the second sheave 7, forming a so-called loose sheave, and the second deflection element 5, including the third sheave 8, forming a fixed sheave. When actuator 3 applies a stronger pre-tension to the endless traction device 2, the piston rod 12 and the first deflection element 4 move upward in the diagram of Figure 1a. Compared to a conventional tensioning system that does not have a second deflection element 5 that interacts with the first deflection element 4 like a pulley, the distance the piston rod 12 needs to travel to change the same pre-tension is halved, and the actuator naturally needs to apply a correspondingly greater force.

[0032] Figure 1a also shows that the wrap angle α of the second sheave 7 is less than 90°. However, it is also possible to ensure that the strands are aligned with each other when entering and leaving the tensioning system 1 by having an angle of exactly 90° and having wrap angles of 90° for both the first sheave 6 and the second sheave 7. [Explanation of Symbols]

[0033] 1. Tensioning System 2 Endless traction device 3 Actuators 4. First deflection element 5. Second deflection element 6. First sieve 7. Second Sheave 8. The third sieve 9. The First Guide 10. The Second Guide 11 cylinders 12 Piston Rods 13 Hydraulic Cylinder 14 Direction of motion 15. Axis of rotation of the first sheave 16. Axis of rotation of the second sheave 17. The axis of rotation of the third sheave α Wrap angle

Claims

1. A tension-applying system (1) for an endless traction device (2) comprising an actuator (3) and a first deflection element (4), wherein the actuator (3) interacts with the first deflection element (4) and can move the first deflection element (4) relative to the endless traction device (2) to change the pretension of the endless traction device (2), the tension-applying system (1) includes a second deflection element (5), the second deflection element (5) engages with the endless traction device (2) and is configured to interact with the first deflection element (4) and the endless traction device (2) like a pulley, the tension-applying system (1) characterized in that one of the first deflection element and the second deflection element forms a loose sheave required for the pulley, and the other deflection element of the first deflection element and the second deflection element forms a fixed sheave required for the pulley.

2. The tension-applying system (1) according to claim 1, characterized in that the first deflection element (4) comprises a first sheave (6) and a second sheave (7), and the first sheave (6) and the second sheave (7) are arranged such that the endless traction device (2) is continuously deflected by the two sheaves (6, 7).

3. The tension-applying system (1) according to claim 1, characterized in that the second deflection element (5) comprises a third sheave (8).

4. The tension-applying system (1) according to claim 2, characterized in that the second deflection element (5) is arranged such that the endless traction device (2) is deflected by the second deflection element (5) between the deflection by the first sheave (6) and the second sheave (7).

5. The tension-applying system (1) according to claim 2, characterized in that the first sheave (6) is provided with a first guide (9) and the second sheave (7) is provided with a second guide (10) to prevent the endless traction device (2) from coming into contact with itself.

6. The tension-applying system (1) according to claim 1, characterized in that the actuator (3) comprises a cylinder (11) and a piston rod (12).

7. The tension-applying system (1) according to claim 6, characterized in that the actuator (3) comprises a controllable hydraulic cylinder (13).

8. The tension-applying system (1) according to claim 1, characterized in that the first deflection element (4) interacts with the actuator (3) such that the first deflection element (4) is moved in the direction of motion of the actuator (3) in order to change the pretension of the endless traction device (2).

9. The tension-applying system (1) according to claim 8, characterized in that the second deflection element (5) is arranged in a straight line in the direction of motion (14) of the actuator (3).

10. The tension-applying system (1) according to claim 2, characterized in that the first sheave (6) and the second sheave (7) each have a rotation axis, and the rotation axes are aligned so as to be substantially coaxial with each other.

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