SI26068A - Belt brake with control mechanism for controlled and gradual change of braking force - Google Patents

Abstract

The purpose of the invention is to design a belt brake, which will be adapted to cooperate with the winding drum of the forestry winch, so that it will be possible to stop the rotation of the drum in various pre-selected modes, namely in fast and appropriately jerky mode non-jerky stopping of a predetermined intensity, in which it should be possible to ensure a gradual and precisely controlled reduction of the braking force and thus the release of the brake. The brake mechanism (3) , designed as a one-way hydraulic cylinder (340) with a piston (341), a piston (342) and a corresponding hydraulic connection (343) for supplying hydraulic piston pushing medium (341) along the cylinder (340) against the force inside the cylinder 340) available compression springs (344) in front of the piston (341). The piston rod (342) is movably inserted in the axial direction in the guide (345) available outside the cylinder (341), in the area of which the cylinder (341) is attached to said lever (31) in the central area (313) thereof. The first leg (21) around the brake disc (1) of the wrapped brake belt (2) is connected to the lever (31) of the brake mechanism (3), and the remaining arm (22) of the brake belt (2) is connected to the free end (342 ') piston rods (342) of the secondary actuator (34).

Description

Band brake with regulation mechanism for controlled and gradual change of braking force

The invention relates to a band brake with a regulating brake mechanism, which is, in principle, adapted for use with a forestry winch driven by mechanical or hydraulic drive means via the cardan shaft of a tractor, to which this type of winch can be attached. Accordingly, in the field of work procedures and transport, the invention is classified as a drive assembly of lifting devices, especially in the field of forestry winches, and quite concretely it belongs to braking or deceleration devices that are useful when handling any load. According to the international patent classification, such inventions in the context of transport are classified in class B 66 D 5/10, and in the general context of mechanical engineering in class F 16 D 49/12.

The invention is based on the problem of how to design a band brake that will be adapted to cooperate with the winding drum of a forestry winch and will either be integrally implemented with it or rigidly connected to it, i.e. at least mechanically connected without the possibility of mutual twisting, so that rotation will be possible with its help to stop the drums in different pre-selected regimes, namely either in the regime of rapid and accordingly jerky stopping or in the regime of gradual and non-jerky stopping of pre-selected intensity, whereby it should be possible to ensure a gradual and precisely controlled reduction of the braking force and thus loosening of the brake, which would significantly facilitate the towing and loosening of the load during the use of the forestry winch, especially on more demanding terrain.

A band brake as such is known and basically consists of a brake disc with a smooth peripheral surface on which a tensioned brake band is placed around the disc. By pressing the tape to or against the mentioned peripheral surface, a frictional force is created between the latter and the brake band and the corresponding braking torque, which depends on the tightening force, the friction coefficient, the diameter of the disc and the size of the area where the band rests on the surface. The required belt tension is achieved either by fixing one arm of the belt and tightening the remaining arm, or by simultaneously tightening both arms. It depends on the arrangement of the attachment points of the belt arms and the levers with which the necessary belt tensioning is performed each time, whether the brake works in one or the other direction of rotation of the brake disc, which is either properly connected to the assembly that is braked each time, in the case of a forestry winch, i.e. with winding drums, or it is an integral part of this type of assembly.

Band brakes are described e.g. in AT-98564, DE-OS 2 309 740 and DE-OS 1 531 297 and SI 22837 A, and according to the applicant, the most relevant brake is described in SI 25548 A or WO 2019/093972 Al.

The characteristic of the known brake from SI 22837 A is that the management of the brake air tension each time when the brake disc is rotated in one direction enables effective braking and the achievement of the necessary friction force and the corresponding torque for complete rotation of the load, after releasing the brake and rotating the brake disc in the opposite direction direction, braking is enabled with a pre-adjustable and precisely determined torque, which e.g. is sufficient to hold the rope when winding it on the appropriate drum, while the pressure of the tape is evenly distributed over the entire length of the tape on the reel of the karsed. This type of band brake consists of a rotating brake disc, which can represent a part of the peripheral surface of the winding drum, and a brake band, which is placed along a smooth peripheral surface around the circumference of the mentioned brake disc and which can be tightened or loosened with the help of a braking mechanism with which both arms of said brake band are connected. The braking mechanism of this type of brake consists of a control lever and a tensioning assembly, which is connected to said control lever in the central area at a point via a bushing. The brake strap is attached with one of its legs to the control lever, and with the other leg to the tensioning assembly of the mechanism. In this case, the control lever is rotatably located in a fixed pivot at one end, while the opposite end includes a control arm for moving the control lever around the aforementioned pivot. At the same time, an arm of the brake band is attached eccentrically to the pivot point on the control lever at the location between the pivot point and the bushing. Furthermore, the tensioning assembly comprises a stem passing through the said bushing, so that with respect to the bushing, at one end of the stem, a strap arm is attached to the tensioning assembly in the anchorage, while a compression spring is placed on the stem between the said anchorage and the bushing to return the mechanism to its starting position after deactivating the brake. At the opposite end of said stem, a compression spring is clamped between the bushing and the nut to maintain, depending on the position of said nut on the stem, a predetermined pretension of the tape after deactivating the brake. In this case, at least one of the mentioned springs is preferably a compression coil spring, and apart from that, the control arm of the control lever is preferably adapted for connection with a suitable shifting means, especially a hydraulic cylinder. The brake otherwise enables braking to the extent that the traction rope is held while winding it onto the winding drum. However, each time the braking is done while pulling the load, it is done rather quickly and often jerkily, which is relatively unfavorable and makes it difficult to accurately and predictably manipulate the load, and it is also unfavorable from the point of view of generating mechanical loads to which parts of the forestry winch, traction elements are exposed and indirectly, of course, the burden itself.

Band brake with regulating brake mechanism for use with a forestry winch, which is described in SI 25548 A or WO 2019/093972 Al, comprises a brake disc rotating around its rotation axis with a flat and smooth cylindrical peripheral surface, which can optionally be an integral part of the winding drum for winding the towing rope in the mentioned winch. Apart from this, it also includes a flexible, flexible and suitably tensile brake tape, which is placed around the aforementioned peripheral surface of the brake disc and whose ends are connected to each other by means of the brake mechanism in a meaningful oval loop. Said braking mechanism comprises a rigid brake lever, which is pivotally mounted with its first arm in a pivot, and with its remaining arm is articulated with the primary actuator, which optionally represents a hydraulic cylinder or similar means for generating force in a predetermined direction. the brake mechanism also includes a length-variable regulation assembly for regulating the pretension of the brake band, and said regulation assembly is articulated with said brake lever in the central region of the same between said arms. The first end of the brake band is connected to the aforementioned lever of the brake mechanism in the area of the first leg and near the pivot of the lever, while the other end of the brake band is connected to the control assembly, so that by adjusting the length of the control assembly, it is also possible to adjust the pretension of the brake tape, by turning the lever around the pivot in one or the other direction, tighten the brake tape to the aforementioned peripheral surface of the brake disc or loosen it, which then depends on the friction force and consequently the braking torque. The brake mechanism, in addition to the primary actuator articulated with the second leg of the lever, also comprises a seconds actuator, which, together with the control unit for adjusting the pretension of the brake band, is articulated with the aforementioned lever in its central area between the first arm, in the area of which the pivot is located, in the vicinity to which the first arm of the brake band is connected to the mentioned brake lever, and to the second arm, with which the primary actuator is articulated, so that the lever can be rotated around its pivot both with the help of the primary actuator and with the help of the secondary actuator, which in one of the versions is may be available as a hydraulic cylinder. Activation of the brake designed in this way is done by turning the brake lever counterclockwise, which is possible either with an active or inactive secondary actuator. When the actuator is inactive for seconds and braking takes place with the help of the primary actuator in the same way as with other previously known brakes from the state of the art, i.e. quickly and jerkily. In this case, however, after the appropriate adjustment of the distance of the brake band anchorage on the brake mechanism and when the secondary actuator is activated, the geometry of the brake mechanism in relation to the brake band changes, so the braking itself can be correspondingly softer and less jerky. Unfortunately, this does not mean that the release of the brake is softer and less jerky. In cases where the winding drum is twisted, and the load is attached to the rope and is in a position in which the rope would unwind from it if the drum were not twisted, the release of the brake is completely uncontrolled, which means that from the moment the brake is released, the drum is completely untwisted, and the speed of unwinding the rope in such a case depends only on the speed or the tendency of the load to move, which can only slide down the slope, but in the worst case it can also fall freely. In such a case, it is in principle possible to control the sliding or falling of the load, namely with periodic or by successively activating and releasing the brake, however, in such a case braking and releasing is jerky and can also be uncontrolled, and this kind of process is relatively imprecise, often even risky or dangerous, because in cases of manipulation of the load in demanding field conditions, even by a qualified user, it can also be associated with the risk of unintentional overloading and injuries.

The proposed invention relates to a band brake with a regulating braking mechanism, especially for use with a forestry winch, wherein said regulating braking mechanism is adapted for a controlled and gradual change of the braking force. This type of brake includes a rotating brake disc with a flat and smooth cylindrical peripheral surface around its axis of rotation, which optionally represents an integral part of the winding drum for winding the towing rope in a forestry winch, as well as a flexible, flexible and suitably tensile brake band, which is installed around the mentioned peripheral surface of the brake disc and whose arm is connected to each other by means of the brake mechanism in a tangentially closed loop on both sides with respect to the circular disc. In this case, the mentioned brake mechanism includes a rigid brake lever, which is pivotally located in the pivot with its first arm, and is articulated on its remaining free arm with a primary actuator, which represents a means of generating force in a predetermined direction, while the secondary actuator, which, together with the regulation assembly for adjusting the pretension of the brake band, is attached to the said lever in its central region, i.e. between the first leg with the pivot, near which the first leg of the brake band is connected to the lever, and the second leg, with which articulated primary actuator. Correspondingly, the lever is then rotatable about its pivot either with the help of the primary actuator or with the help of the secondary actuator.

According to the invention, it is envisaged that in seconds the actuator is designed as a unidirectional hydraulic cylinder with a piston, a piston rod and a suitable hydraulic connection for the supply of hydraulic medium to push the piston along the cylinder against the force inside the cylinder in front of the piston of the available compression spring, with the piston rod in the axial direction movably inserted into a guide available outside the cylinder, in the area of which the cylinder is attached to said lever in the central area thereof. Each time the position of the piston rod and indirectly the entire cylinder in relation to the lever is adjustable in advance with the help of a regulation mechanism, and the second leg of the brake band is connected to the free end of the piston rod, the first leg of which is connected to the mentioned lever near the pivot, namely at a suitable distance from the latter in direction towards the other arm of the lever.

In the secondary actuator, due to the effect of the pressure medium on the piston and the elastic deformability of the pressure spring available in front of the piston, the piston rod is movable along the guide in the direction away from the lever, and at the same time as the piston rod, the other leg of the brake band attached to it is also movable in the direction away from the lever at its free end , the tension of which relaxes accordingly. In this case, the aforementioned compression spring is preferably a disc spring, and in particular a set of at least two disc springs arranged coaxially with each other.

In one of the embodiments of the invention, the mentioned primary actuator represents a pressure spring working in the direction towards the second arm of the brake lever in terms of tensioning the brake band. In this case, said spring is preferably a helical compression spring, which is installed in a suitable housing and/or guided in/on a suitable guide. Said spring is adapted to generate a predetermined force with which the primary actuator is pressed against the second arm around the pivot of the pivoting lever and which, when the secondary actuator is inactive, is sufficient for the necessary tensioning of the brake band to ensure sufficient frictional force between the brake disc and the brake band and thus each time to brake the required braking torque.

In a further possible implementation of the invention, the mentioned primary actuator is a hydraulic cylinder, which is adapted to generate a predetermined force with which the primary actuator can be pressed against the second arm around the pivot of the pivoting lever and which, when the secondary actuator is inactive, is sufficient for the necessary tensioning of the brake band to ensure sufficient frictional forces between the brake disc and the brake band and thus the required braking torque every time.

In the following, the invention will be explained in more detail on the basis of an example of implementation, which is illustrated in the attached sketch, where

fig. 1 shows a band brake according to the invention in a drawing;

fig. 2 increased brake according to Fig. 1 in the activated i.e. rotate the state and also in the drawing;

fig. 3 as well as the increased brake according to FIG. 1, but in a deactivated state, namely during gradual relaxation, also in the drawing.

In FIG. 1 schematically illustrated example of the implementation of a band brake with a regulation brake mechanism 3 for controlled and gradual change of the braking force is adapted especially for use with a forestry winch. The brake comprises a rotating brake disc 1 with a flat and smooth cylindrical peripheral surface 11 around its axis of rotation, which optionally represents an integral part of the winding drum for winding the towing rope in a forestry winch, but it can be connected to the winding drum in a non-detachable or detachable manner, in any case so that the torque from the winding drum is fully transmitted to the brake disc 1 or vice versa. In addition to the mentioned brake disc 1 and the brake mechanism 3, the brake also includes a flexible, flexible and grippy tensile brake band 2, which is placed around the mentioned peripheral surface 11 of the brake disc 1, so that the arms or the free ends 21, 22 of the tape 2 are connected to each other with the help of the brake mechanism 3 in a loop closed tangentially from both sides with respect to the circular reel 1.

Said brake mechanism 3 comprises a rigid grip and, in the case shown, a two-arm brake lever 31, which with its first arm 311 is pivotally located in the pivot 310, and on its remaining arm 312 is articulated with the primary actuator 32, which represents a means of creating a predetermined forces in a predetermined direction.

The brake mechanism 3 further comprises a secondary actuator 34, which, together with the regulation assembly 33 for adjusting the pretension of the brake band 2, is attached to the said lever 31 in its central region 313 between the first arm 311 and the pivot point 310, near which it is connected to the lever 31 the first arm 21 of the brake band 2, and the second arm 312, with which the primary actuator 32 is articulated, so that the lever 31 around its pivot point 310 can then optionally be rotated either with the help of the primary actuator 32 or with the help of the secondary actuator 34.

The already designed brake works in principle, at least in terms of braking and releasing, if only the primary actuator 32 in the direction towards the free end of the second leg 312 of the brake lever 31 provides a force of sufficient strength, which, with the help of the intensity of the pressure of the brake band 2 on the circumference of the brake disc 1, creates a sufficient frictional force or sufficient braking torque. The necessary pre-tension of the brake band 2 in relation to the available stroke of the primary actuator 32 can be regulated with the secondary actuator 34 and its regulation mechanism 33. In such a case, it would also be possible to regulate the strength of the braking force with the intensity of the force on the primary actuator 32, similar to how it is done for brakes from the state of the art. However, in such a case, the problem of uncontrolled operation of the brake when it is released would remain completely unsolved.

In contrast to this, in the brake according to the invention, it is envisaged that the secondary actuator 34 is designed as a unidirectional hydraulic cylinder 340 with a piston 341, a piston rod 342 and a corresponding hydraulic connection 343 for the supply of hydraulic medium to push the piston 341 along the cylinder 340 against the force inside the cylinder 340 compression springs 344 inserted in front of the piston 341. The piston rod 342 is movably inserted in its axial direction in a guide 345 available outside the cylinder 341, in the area of which the cylinder 341 is attached to the mentioned lever 31 in its central area 313.

Each time the starting position of the piston rod 342 and indirectly of the entire cylinder 340 with respect to the lever 31, e.g. with the initial position of the piston 341 in the cylinder 340 and the unincreased pressure of the pressure medium and the unloaded pressure spring 344, it is also pre-adjustable according to the invention with the help of the regulation mechanism 33. The second leg 22 of the brake band 2 is connected to the free end of the piston rod 342 extending outside the cylinder 340, which the first arm 21 is connected to the lever 31 near the pivot 310, namely at a suitable distance from the latter in the direction towards the second arm 312 of the lever 31.

Accordingly, in the secondary actuator 34, due to the effect of the pressure medium on the piston 341 and the elastic deformability in front of the piston 341 of the available pressure spring 344 along the guide 345, the piston rod 342 is movable in the direction away from the lever 31, and at the same time as the piston rod 342 is in the direction away from the lever 31 also movable at its free end 342', the second arm 22 of the brake band 2 is attached to it, the tension of which accordingly relaxes. Namely, when, by acting on the other end 312 of the pivot 310 of the pivoting lever 31, the brake band 2 is tensioned to the extent that the braking force is ensured, in such a state, by activating the secondary actuator 34 and moving the piston 341 against the force of the spring 344, and consequently then by moving the piston rod 342, the second arm 22 of the brake band 2 attached to the piston rod 342 is loosened, which leads to a slight and very gradual loosening of the brake.

According to the invention, it is further provided that, mainly due to high loads and relatively small necessary movements under load, the aforementioned compression spring 344 represents a circular spring, and for the sake of flexibility and adjustment of the sensitivity of the assembly, it is especially preferable if the compression spring 344 represents the assembly or assembly of at least two disc springs arranged coaxially with each other.

When the use of the brake is foreseen in those technical areas where the need for variable braking intensity is expected, the primary actuator 32 can represent a hydraulic cylinder adapted to generate a predetermined force with which the primary actuator 32 can be pressed against the second arm 312 around the pivot 311 of the rotatable lever 31 and which, when the secondary actuator 34 is inactive, is sufficient for the necessary tensioning of the brake band 2 to ensure sufficient frictional force between the brake disc 1 and the brake band 2 and thus to brake the necessary braking torque.

In certain areas of technology, e.g. with forestry winches, in most cases there is actually no need for real-time adjustment of the braking force. Namely, the brake slows the rotation of the winding drum and works alternatively with the clutch, through which the torque from the drive means is transmitted to the drum. When the drum is rotating, the brake is fully disengaged and the drum is driven via an activated clutch. When the clutch is deactivated, the drive is interrupted, but the drum must be boiled at the same time, otherwise the rope with the load could unwind due to the weight of the load itself. In such a situation, it is therefore in principle sufficient if the primary actuator can generate sufficient force on the free end 312 of the brake lever 31, which ensures quick and reliable activation of the brake and which then also permanently maintains and maintains the brake in the activated state, the brake disc 1 and with it also and the winding drum is in the rotated state. However, when in such a situation the secondary actuator 34 is activated by supplying the necessary amount, the tension of the brake band 2 gradually relaxes as the piston rod 342 moves. The amount of hydraulic medium supplied through the connection 343 of the hydraulic cylinder 340 can be controlled very precisely with the help of a suitable valve and control unit, so the relaxation of the braking force can also be controlled very precisely.

In the considered example of the implementation of the invention and in the case of the application of the invention in the field of devices with a constant braking force, the primary actuator 32 can therefore represent a spring 323. In the example shown, the spring 323 is installed in a suitable housing 321 and/or guided on a suitable guide 322 and is modified to create a predetermined force with which the primary actuator 32 is pressed against the second arm 312 around the pivot 311 of the swivel lever 31 and which, with the secondary actuator 34 inactive, is sufficient for the necessary tensioning of the brake band 2 to ensure sufficient frictional force between the brake disc 1 and the brake band 2 and thus to brake the required braking torque. As a pressure spring 323, a helical spring can be used, which can be pre-set, e.g. to 120% of the required braking force and ensures permanent brake braking of the winder drum, whereby this braking force can then be temporarily partially or completely eliminated by activating the secondary actuator 34, either by enabling the rotation of reel 1 and the winder drum of the winch as one direction due to the winding of the rope while pulling the load or in the other direction during the unwinding of the rope due to pulling it to the load or due to loosening of the tension of the towing rope due to manipulation with the load and the like.

Claims (7)

1. A band brake with a regulating brake mechanism (3) for controlled and gradual change of the braking force, especially for use with a forestry winch, comprising a rotating brake disc (1) with a flat and smooth cylindrical peripheral surface (11) around its axis of rotation, which choice is an integral part of the winding drum for winding the towing rope in the forestry winch, as well as the flexible, flexible and tensile-resistant brake strap (2), which is placed around the mentioned peripheral surface (11) of the brake disc (1) and whose end (21 , 22) are connected to each other by means of a brake mechanism (3) in a tangentially closed loop on both sides with respect to the circular disc (1), whereby the mentioned brake mechanism (3) comprises a suitably rigid lever (31) which sticks with its first arm (311) is pivotally mounted in a pivot (310) and is articulated on its remaining free arm (312) with a primary actuator (32) which represents a means of generating a force in a predetermined direction, while a second ami actuator (34), which, together with the regulation assembly (33), is intended for regulating the pretension of the brake band (2), attached to the mentioned lever (31) in its central area (313) between the first arm (311) and the pivot (310) , near which the first end (21) of the brake band (2) is connected to the lever (31), and the second arm (312), with which the primary actuator (32) is articulated, so that the lever (31) rotates around its pivot ( 310) then optionally rotatable either with the help of the primary actuator (32) or with the help of the secondary actuator (34), characterized by the fact that the secondary actuator (34) is designed as a unidirectional hydraulic cylinder (340) with a piston (341), the piston rod (342) and the corresponding hydraulic connection (343) for the supply of hydraulic medium for pushing the piston (341) along the cylinder (340) against the force inside the cylinder (340) in front of the piston (341) of the available compression spring (344), whereby the piston rod (342) movably inserted in the axial direction outside the cylinder (341 ) ext extendable guide (345), in the area of which the cylinder (341) is attached to said lever (31) in the central area (313) thereof, and wherein the respective position of the piston rod (342) and indirectly of the entire cylinder (340) with respect to the lever (31) adjustable in advance by means of the regulating mechanism (33), and the second leg (22) of the brake band (2) is connected to the free end of the piston rod (342), the first leg (21) of which is connected to the lever (31) nearby pivot (310), namely at a suitable distance from the latter in the direction towards the second arm (312) of the lever (31). 2. The band brake according to claim 1, characterized by the fact that in the secondary actuator (34) there is a piston (342) due to the effect of the pressure medium on the piston (341) and the elastic deformability in front of the piston (341) of the available pressure spring (344) along the guide ( 345) is movable in the direction away from the lever (31), and at the same time as the piston rod (342) is also movable in the direction away from the lever (31) at its free end (342'), the second leg (22) of the brake band (2) is attached to it. , the tension of which relaxes accordingly. 3. A band brake according to claim 1 or 2, characterized in that said pressure spring (344) is a disk spring. 4. A band brake according to claim 1 or 2, characterized in that the pressure spring (344) represents a set of at least two circular springs arranged coaxially with each other. 5. Band brake according to any one of claims 1-4, characterized in that the primary actuator (32) represents a pressure spring (323) operating in the direction towards the second arm (312) of the brake lever (31) in terms of tensioning the brake band (2). . 6. A band brake according to claim 5, characterized in that it comprises a helical pressure spring (323), which is installed in a suitable housing (321) and/or guided in/on a suitable guide (322) and is adapted to generate a predetermined force , with which the primary actuator (32) can be pressed against the second arm (312) around the pivot (310) of the swivel lever (31) and which, when the secondary actuator (34) is inactive, is sufficient for the necessary tensioning of the brake band (2) to ensure sufficient frictional force between brake disc (1) and brake bands (2) and thus to brake the necessary braking torque. 7. A band brake according to any one of claims 1-4, characterized in that the primary actuator (32) is a hydraulic cylinder adapted to generate a predetermined force by which the primary actuator (32) can be pressed against the second arm (312). around the pivot (310) of the swivel lever (31) and which, when the secondary actuator (34) is inactive, is sufficient for the necessary tensioning of the brake band (2) to ensure sufficient frictional force between the brake disc (1) and the brake band (2) and thus for braking required braking torque.