WO2022055435A1

WO2022055435A1 - Belt brake with regulating mechanism enabling controlled and gradual braking force adjustment

Info

Publication number: WO2022055435A1
Application number: PCT/SI2021/000002
Authority: WO
Inventors: David KOZINC
Original assignee: Tajfun Planina Proizvodnja Strojev, D.O.O.
Priority date: 2020-09-11
Filing date: 2021-03-29
Publication date: 2022-03-17
Also published as: SI26068A

Abstract

The purpose of the invention is to create a belt brake, which should be suitable for cooperation with a winding drum in a forestry winch, so that by means of such brake each rotating of said drum could be stopped in various pre-determined operation modes, namely either in the case of sudden and stressful braking, or in the case of smooth and gradual braking with controlled intensity, wherein in particular also a gradual and exactly controlled decreasing of the braking force and releasing of the brake therewith would have to be assured. A brake mechanism (3) in a brake according to the invention, in addition to a primary actuator (32), also comprises a secondary actuator (34), which is conceived as a single acting hydraulic cylinder (34), comprising a piston (341), a piston rod (342) as well as a hydraulic inlet (343) for supplying a hydraulic media suitable for displacing the piston (341) along the cylinder (340) against the force of the compression spring (344), which is embedded within the cylinder (340) in front of the piston (341). Said rod (342) is axially movable inserted within a guide (345), in the area of which said cylinder (341) is attached to said lever (31) in the central area (313) thereof. The first terminal portion (21) of the brake belt (2), which is placed on the circumferential surface of the belt disc (1), is connected to a lever (31) of a brake mechanism (3), while the residual terminal portion (22) of said brake belt (2) is attached to a free terminal portion (342') of a piston rod (342) in said secondary actuator (34).

Description

Belt brake with regulating mechanism enabling controlled and gradual braking force adjustment

The invention refers to a belt brake, which is equipped with a regulating mechanism and is generally adapted for use in a forestry winch, which is powered by means of mechanic or hydraulic powering means via a cardan shaft on a tractor, on which such winch can be mounted. Consequently, such invention in the field of working operation and transporting belongs to transmission components in hoisting appliances, in particular to forestry winches, and in particular to braking and decelerating appliances, which are used by manipulating with each load. Pursuant to the International patent Classification such invention belongs to Class B 66 D 5/10, and in the case use in the other fields of mechanical engineering also to Class F 16 D 49/12.

The purpose of the invention is to create a belt brake, which should be suitable for cooperation with a winding drum in a forestry winch, and should be either made integrally with it, or should be mechanically connected therewith without any possibility of rotating one relatively to another, so that by means of such brake each rotating of said drum could be stopped in various pre-determined operation modes, namely either in the case of sudden and stressful braking, or in the case of smooth and gradual braking with controlled intensity, wherein in particular also a gradual and exactly controlled decreasing of the braking force and releasing of the brake therewith would have to be assured, which would during the use of a forestry winch essentially contribute to easily towing and also releasing of each load in particularly on a difficult terrain. A belt brake as such is known and generally consists of a brake disc with a smooth circumferential surface, around which a properly tensioned brake belt is placed. By tensioning said belt, a friction force is generated between said circumferential surface and the brake belt, and consequently also the corresponding braking torque, which depends on the tensioning force, friction coefficient, diameter of said disc as well as on dimensions of the contact area between the belt and the surface. Each required tensioning of the belt is achieved either by means of fixing the one terminal portion of the belt and tensioning the other terminal portion, or also by means of simultaneously tensioning of both terminal portions of the belt. Efficiency of the brake in one or another direction of turning said disc depends on arrangement of points, in which the terminal portions of said belt and each belonging lever are connected with each other, wherein on the other hand said disc is either connected with each braked assembly, or may alternatively represent an integral part of such braked assembly.

Belt brakes are disclosed e.g. in AT-9856, DE-OS 2 309 740 and SI 22837, and the most relevant brake in the view of the opinion of the applicant is disclosed in SI 25548 i.e. WO 2019/093972 Al.

Regarding the known brake pursuant to SI 22837 A, controlling of each tension of the brake belt enables generating of a sufficient friction force and braking torque for the purpose of efficiently braking of disc rotating in its first direction due to absolutely stopping of each load, while by releasing of the brake and rotating the disc in its opposite direction braking with a pre-determined and precisely adjusted braking torque is enabled, which allows some retaining of the cable by coiling thereof on a winding drum, wherein the pressure of the belt towards the surface of the brake disc should be uniformly distributed along the complete contact surface between the disc and the belt. Such brake consists of a rotatable brake disc, which may be an integral part of circumferential surface of a winding drum, as well of a brake belt, which is placed around the circumferential surface of said disc and may be tensioned or released by means of a suitable braking mechanism, to which both terminal portions of said brake belt are attached. Said braking mechanism in such brake consists of an actuating lever and a tensioning assembly, which is attached to said actuating lever in its central area and via a bush. One of the terminal portions of the belt is attached to the actuating lever, whole the residual terminal portion of the belt is attached to the tensioning assembly of said mechanism. Said actuating lever is with its first terminal portion pivotally embedded in fixed a pivot point, while on its residual terminal portion it is furnished with an actuating arm, which serves for pivoting of the lever around said pivot point. A terminal portion of the brake belt is attached to said actuating lever in the area between the pivot point and the bush, namely eccentrically with respect to the pivot point. Said tensioning assembly comprises a bolt, which extends throughout said bush, so that, when observed in view of said bush, a terminal portion of the brake belt is fastened in an attachment point on the one terminal portion of said bolt, while between said attachment point and the bush there is a compression spring placed on said bolt, which is suitable for returning the mechanism after deactivation of the brake back to is initial position. On the opposite terminal portion of said bolt, namely between said bush and a nut, there is a further compression spring placed on said bolt, which is intended for maintaining of previously adjusted tension in the belt after deactivation of the brake, depending on position of said nut. At least one of said springs is a helical compression spring, and moreover, said actuating arm of the actuating lever is preferably adapted for connection with a suitable transmission means, in particular hydraulic cylinder. Such brake enables braking in such extent, that retaining of the towing cable is assured by coiling thereof on a winding drum. However, each braking as such by towing of each load is performed suddenly and intermittent and is therefore stressful and unpleasant, and makes each precise and predictable manipulating of each load quite impossible, while on the other hand this may also lead to generation of reasonable mechanical stresses and loadings, to which the load, each towing elements and in particular also various components of the forestry winch are exposed during the use.

A belt brake with an regulating mechanism, which is used in combination with a forestry winch and is disclosed in SI 25548 A or WO 2019/093972 Al, comprises a brake disc, which is furnished with a smooth and uniform cylindrical circumferential surface and is rotatable around the rotation axis thereof, which may generally represent an integral part of winding drum for coiling of the winding cable in a forestry winch. In addition, such brake comprises a flexible and resilient brake belt with suitable tension strength, which is placed around said circumferential surface of the brake disc, so that its terminal portions are via appropriate braking mechanism connected with each other and form a substantially oval loop. Said braking mechanism comprises a properly rigid braking lever, which is by means of its first arm pivotally embedded in a pivot point, and is by means of its second arm pivotally connected with a primary actuator, which is optionally a hydraulic cylinder or any other means for generating of generating a force in each pre-defined direction. Said braking mechanism further comprises a regulation assembly with extendable length, which is used for adjusting each tension of the belt, while said regulating assembly is pivotally connected to said brake lever in its central area between both arms. The first terminal portion of the belt is connected to said lever of the braking mechanism in the area of its first arm and adjacent to the pivot point, while the second terminal portion of die belt is connected to the regulation assembly, so that by adjusting the length of the regulation assembly also pre-tensioning of the brake belt can be adjusted, and the belt can be either pressed towards the surface of the brake disc or released by means of pivoting the lever around its pivot point, by which then each required friction force and braking torque are generated. Said braking mechanism, in addition to said primary actuator, ehich is connected with the second terminal portion of the belt, also comprises a secondary actuator, which is together with said regulating assembly for adjusting of each pre-tension of the brake belt pivotally connected with said lever in its central area between its first arm, in the area of which the pivot point is located, to, adjacent to which the first terminal portion of the brake belt is attached, and the secondary arm, to which the primary actuator is pivotally connected, so that the lever can be pivoted around its pivot point either by means of the primary actuator or by means of the secondary actuator, which is in one of possible embodiments a hydraulic cylinder. Activation of such brake is performed by counter clockwise pivoting said braking lever, which is feasible either by active or inactive secondary actuator. When the secondary actuator is inactive and is braking initiated by means of the primary actuator similarly like in various other state of the art brakes, which means suddenly and intermittent. However, upon properly adjusting of the distance of the brake belt on the braking mechanism and by activation of the secondary actuator the geometry of the braking mechanism relatively to the brake belt is changed to such extent that each braking may be performed smoothly and gradually. This however does not mean at all, that also releasing of the brake becomes smooth and gradual. When the winding drum is braked, and each load is attached to a towing cable in position, in which the cable could be uncoiled from the released winding drum, then releasing of such brake is completely uncontrolled, which means that if the brake is released i.e. deactivated, the winding drum nay freely rotate, and the velocity of the cable depends on velocity or tendency of movement of the load, which may either slide along each terrain, or even freely fall. In such cases, said sliding or free-falling of the load may be controlled by means of occasional or periodical activation and releasing of the brake, which leads to stressfill intermittent braking without any reasonable control, so that such process is due to inertia of the load as well as due to extension and accomodation of the each towing elements like cables, chains or other couplings, pretty unprecise or even dangerous and risky, since by manipulating with a load on a difficult terrain even from the side of a skilled user there is always certain risk on overloading or damaging of certain components.

The proposed invention refers to a belt brake with regulating mechanism enabling controlled and gradual braking force adjustment, which is in particular intended for use in a forestry winch, wherein said regulating mechanism is suitable for controlled and gradually adjusting of each braking force. Such a brake comprises a brake disc, which is rotatable around its rotation axis and is furnished with a continuous and smooth circumferential surface, which is optionally integrated within a winding drum, which is in a forestry winch used for winding of a towing cable, as well as a flexible brake belt with sufficient tension strength, which is placed on said circumferential surface of said brake disc, so that both terminal portions thereof are by means of a braking mechanism connected with each other by forming a loop, which approaches tangentially to said brake disc on both sides thereof. Said regulating mechanism comprises a properly rigid lever, which is by means of its first arm pivotally embedded within a pivot point and is by its second arm linked to a primary actuator, namely a means for generating each required force in a pre-determined direction, while a secondary actuator, which is together with a suitable regulating assembly foreseen for adjustment of pre-tensioning of said brake belt, is attached to said lever in the central area thereof, namely between the first arm with the pivot point, adjacent to which the first terminal portion of the braking belt is attached to said lever, and the second arm, to which said primary actuator is linked. Consequently, said lever can be pivoted around its pivot point either by means of said primary actuator or by means of said secondary actuator.

The invention however proposes that said secondary actuator is conceived as a single acting hydraulic cylinder, which comprises a piston, a piston rod as well as hydraulic connectors for supplying a hydraulic media suitable for displacing said piston along the cylinder against the force of a compression spring, which is embedded within said cylinder in front of the piston, wherein said rod is axially movable inserted within a guide, which is located outside of the cylinder and in the area of which said cylinder is attached to said lever in the central area thereof. Each position of the piston rod and consequently also of the cylinder relatively to the lever is pre-adjustable by means of a regulating assembly, and the free terminal portion of said piston rod is connected with said second terminal portion of the brake belt, the first terminal portion of which is connected to the lever in the adjacency of the pivot point, however at a suitable distance apart from said pivot point in a direction towards the second arm of the lever.

The free terminal portion of said piston rod in the secondary actuator is due to exposure of the piston to said hydraulic media as well as due to elastic deformability of said compression spring in front of the piston displaceable along said guide in a direction away from the lever, while simultaneously with said rod also the second terminal portion of the brake belt, which is attached to said rod, is displaceable away from the lever, by which also the tension therein is simultaneously decreasing. Said compression spring is preferably a cup spring, in particular a set consisting of at least two coaxially arranged cup springs. In one of the embodiments of the invention, said primary actuator is a compression spring, which is acting in a direction towards the second arm of the brake lever for the purpose of tensioning said brake belt. Said spring is preferably a helical compression spring, which is mounted within a suitable casing and/or guided in/on a suitable guide. Such spring is suitable for generating a pre-determined force, by which said primary actuator is pressed towards the second arm of said around its pivot point pivotable lever and which is by inactive secondary actuator sufficient for providing each required friction between the brake disc and the brake belt and each required torque for the purpose of braking.

In a further possible embodiment of the invention, said primary actuator is a hydraulic cylinder, which is suitable for generating a pre-determined force, by which said primary actuator is pressed towards the second arm of said around its pivot point pivotable lever and which is by inactive secondary actuator sufficient for providing each required friction between the brake disc and the brake belt and each required torque for the purpose of braking.

The invention will be explained in more detail on the basis of an embodiment, which is presented in the attached drawing, in which

Fig. 1 is a belt brake in its top view,

Fig. 2 is enlarged top view of the brake according Fig. 1 in its activated state i.e. by braking; and

Fig. 3 is also an enlarged top view of the brake according Fig. 1, however in another state, namely by gradually releasing thereof.

An embodiment of a belt brake is schematically presented in Fig. 1, in which the brake is furnished with a regulating mechanism 3, which enables controlled and gradual adjustment of each braking force and is in particular useful in a forestry winch. Such brake comprises a brake disc 1, which is rotatable around its rotation axis and is furnished with a continuous and smooth circumferential surface 11, which is optionally integrated within a winding drum, which is in a forestry winch used for winding of a towing cable, or may be optionally just connected therewith either in a detachable or non-detachable maimer, but in each case in such a way, that each torque is entirely transferred from said winding drum to said brake disc 1, or vice versa. In addition to said brake disc 1 and said regulating mechanism 3, such brake also comprises a flexible brake belt 2 with sufficient tension strength, which is placed on said circumferential surface 11 of said brake disc 1, so that both free ends i.e. terminal portions 21, 22 thereof are by means of a braking mechanism 3 connected with each and form forming a loop, which approaches tangentially to said brake disc 1 on both sides thereof.

Said regulating mechanism 3 comprises a rigid lever 31, which is in the presented embodiment a double-arm lever, and is by means of its first arm 311 pivotally embedded within a pivot point 310, and by means of its second arm 312 linked to a primary actuator 32, which is a means for generating each required force in a predetermined direction.

Said regulating mechanism 3 also comprises a secondary actuator 34, which is together with a suitable regulating assembly 33, which is suitable for adjustment of pre-tensioning of said brake belt 2, attached to said lever 31 in the central area 313 thereof, namely between the first arm 311 with the pivot point 310, adjacent to which the first terminal portion 21 of the braking belt 2 is attached to said lever 31, and the second arm 312, to which said primary actuator 32 is linked, so that said lever 31 can then be pivoted around its pivot point 310 either by means of said primary actuator 32 or by means of said secondary actuator 34.

Such brake is generally able to operate at least in the sense of braking or releasing, if said primary actuator 32 is capable to generate a sufficient force in a direction towards the terminal portion of the second arm 312 of the brake lever 31, which depending on intensity of said force then along the circumference of the brake disc 1 generates a sufficient friction force and each required braking torque. Each required pre-tensioning of the brake belt 2 with respect to each disposable movement of the primary actuator is adjusted by means of the secondary actuator 34 and a regulating mechanism 33 there-on. Like in the brakes known from the stale of the art, also in such case the intensity of each braking force may be adjusted in correlation with the force on said primary actuator 32. However, in such case each releasing of the brake is sudden and intermittent, so that the problem of controlling of releasing would still persist and remain unsolved.

On the contrary, the invention proposes a brake, in which said secondary actuator 34 is conceived as a single acting hydraulic cylinder 340, which comprises a piston 341, a piston rod 342 and hydraulic connectors 343 for supplying a suitable hydraulic media for displacing said piston 341 along the cylinder 340 against the force of a compression spring(344, which is embedded within said cylinder 340 in front of the piston 341. Said rod 342 is axially movable embedded within a guide 345, which is located outside of the cylinder 341 and in the area of which said cylinder 341 is attached to said lever 31 in the central area 313 thereof.

Pursuant to the invention, each initial position of the piston rod 342 and consequently also of the cylinder 340 relatively to the lever 31, e.g. in the initial position of the piston 341 within the cylinder 340 and by released pressure of said hydraulic media and released compression spring 344, is adjustable in advance by means of a regulating assembly 33. The free terminal portion of said piston rod 342, which protrudes outside of the cylinder 340, is connected with the second terminal portion 22 of the brake belt 2, while the first terminal portion 21 of said band 2 is connected to the lever 31 in the adjacency of the pivot point 310, however also at a suitable distance apart from said pivot point 310 in a direction towards the second arm 312 of the lever 31.

Consequently, the piston rod 342 in the second actuator 34 is due to the impact of said hydraulic media towards the piston 341 and also due to elastic deformability of said compression spring 344 displaceable along the guide 345 in a direction away from the lever 31 , by which also the second terminal portion 22 of the brake belt 2 is displaced, since it is attached to the free end portion 342’ of the rod 342, so that also the tension within the belt 2 is herewith gradually reduced. Namely, when the first actuator 32 is acting towards the first arm 312 of said around its pivot point 310 rotatable lever 31, the brake belt 2 is tensioned up to the level, which assures achieving of each required braking force, and when in such situation also the second actuator 34 is activated and its piston 341 together with the belonging rod 342 is displaced against the force of its compression spring 344, then the second terminal portion 22 of the brake belt 2 is released, since it is attached to said piston rod 342, which then leads to smoothly and really gradual releasing of the brake.

The invention further provides that merely due to relatively high stresses and relatively small displacements, which are expected in its loaded state, said compression spring 344 is a cup spring, while for the purposes of flexibility and adjustment of sensibility of a device it is in particular preferred, that said compression spring 344 is an assembly i.e. a set, which consists of at least two coaxially arranged cup springs.

In particular when the brake should be suitable for application in certain technical fields, where also intensity of braking should be changeable, then said primary actuator 32 can be a hydraulic cylinder, which is suitable for generating a predetermined force, by which said primary actuator 32 is pressed towards the second arm 312 of said around its pivot point 310 pivotable lever 31 and which is by inactive secondary actuator 34 sufficient for providing each required friction between the brake disc 1 and the brake belt 2 and each required torque for the purpose of braking.

On the contrary, in certain technical fields, like in forestry winches, there is actually no need on changing the braking force, The brake must namely just maintain the rotating drum in its stopped position and is operating synchronized and alternatively with a clutch, via which a torque is transferred from the powering means to the winding drum for the purpose of establishing rotation thereof. When the drum is rotating, the brake is totally released and the drum is rotating via said activated clutch. As soon as the clutch is deactivated and the torque transmission is interrupted, the drum must be immediately stopped and, since on the contrary braked the cable would start decoiling from the drum due to the load and its weight. In such circumstances it is practically sufficient, if the primary actuator 32 is capable to produce a sufficient force towards the second terminal portion 312 of the brake lever 31, which assures quick and reliable activating of the brake, which is then maintained, so that also the brake is maintained in its activated state, in which the brake disc 1 and consequently the winding drum are braked. As soon as by means of gradually supplying each required quantity of hydraulic media into the second actuator 34, the piston rod 342 is displaced and tension within the brake belt 2 is gradually released. Quantity of supplied hydraulic media into the cylinder 340 through said hydraulic connectors 343 can be precisely regulated by means of a suitable valve with a belonging control unit, so that also releasing of the brake can be precisely controlled.

Regarding this lastly discussed embodiment of the invention, which is suitable for using together with appliances with a pre-determined and uniform braking force, said primary actuator 32 may simply be a spring 323. In the shown embodiment, said spring 323 is mounted within a suitable casing 321 and/or guided in/on a suitable guide 322, and is therefore suitable for generating a pre-determined force, by which said primary actuator 32 is pressed towards the second arm 312 of said around its pivot point 310 pivotable lever 31 and which is by inactive secondary actuator 34 sufficient for providing each required friction between the brake disc 1 and the brake belt 2 and therefore also each required torque for the purpose of braking. As said spring 323 e.g. a helical compression spring can be used, which is in a forestry winch brake pre-tensioned to such extent, that it produces around 120% of each required braking force in order to assure said permanent braking of the winding drum, upon which, optionally, such adjusted braking force can be temporarily reduced or totally eliminated by means of activation of said secondary actuator 34, which may be useful either for the purposes of allowing rotation of the winding drum in its first direction due to coiling of the cable by towing each load, or for the purposes of allowing rotation of the winding drum in its opposite direction due to decoiling of the cable either by extending said cable tin order to reach any load, or by temporarily releasing the tension within the towing cable when manipulating with the load, or the like.

Claims

PATENT CLAIMS

1. Belt brake with regulating mechanism (3) enabling controlled and gradual braking force adjustment, which is in particular intended for use in a forestry winch, and which comprises a brake disc (1), which is rotatable around its rotation axis and is furnished with a continuous and smooth circumferential surface (11), which is optionally integrated within a winding drum, which is in a forestry winch used for winding of a towing cable, as well as a flexible brake belt (2) with sufficient tension strength, which is placed on said circumferential surface (11) of said brake disc (1), so that both terminal portions (21, 22) thereof are by means of a braking mechanism (3) connected with each other by forming a loop, which approaches tangentially to said brake disc (1) on both sides thereof, wherein said regulating mechanism (3) comprises a rigid lever (31), which is by means of its first arm (311) pivotally embedded within a pivot point (310) and is by its second arm (312) linked to a primary actuator (32), namely a means for generating each required force in a pre-determined direction, while a secondary actuator (34), which is together with a suitable regulating assembly (33) foreseen for adjustment of pre-tensioning of said brake belt (2), is attached to said lever (31) in the central area (313) thereof, namely between the first arm (311) with the pivot point (310), adjacent to which the first terminal portion (21) of the braking belt (2) is attached to said lever (31), and the second arm (312), to which said primary actuator (32) is linked, so that said lever (31) can be pivoted around its pivot point (310) either by means of the primary actuator (32) or by means of the secondary actuator (34), characterized in that said secondary actuator (34) is conceived as a single acting hydraulic cylinder (340), comprising a piston (341), a piston rod (342) as well as hydraulic connectors (343) for supplying a hydraulic media suitable for displacing said piston (341) along the cylinder (340) against the force of a compression spring (344), which is embedded within said cylinder (340) in front of the piston (341), wherein said rod (342) is axially movable inserted within a guide (345), which is located outside of the cylinder (341) and in the area of which said cylinder (341) is attached to said lever (31) in the central area (313) thereof, wherein each position of the piston rod (342) and consequently also of the cylinder (340) relatively to the lever (31) is pre-adjustable by means of a regulating assembly (33), and wherein the free terminal portion of said piston rod (342) is connected with said second terminal portion (22) of the brake belt (2), the first terminal portion (21) of which is connected to the lever (31) in the adjacency of the pivot point (310), however at a suitable distance apart from said pivot point in a direction towards the second arm (312) of the lever (31).

2. Belt brake according to Claim 1, characterized in that the free terminal portion of said piston rod (342) in the secondary actuator (32) is due to exposure of the piston (341) to said hydraulic media as well as due to elastic deformability of said compression spring (344) in front of the piston (341) displaceable along said guide (345) in a direction away from the lever (31), while simultaneously with said rod (342) also the second terminal portion (22) of the brake belt (2), which is attached to said rod (342), is displaceable away from the lever (31), by which also the tension therein is simultaneously decreasing.

3. Belt brake according to Claim 1 or 2, characterized in that said compression spring (344) is a cup spring.

4. Belt brake according to Claim 1 or 2, characterized in that said compression spring (344) is a set consisting of at least two coaxially arranged cup springs.

5. Belt brake according to anyone of Claims 1 - 4, characterized in that said primary actuator (32) is a compression spring (323), which is acting in a direction towards the second arm (312) of the brake lever (31) for the purpose of tensioning said brake belt (2).

6. Belt brake according to Claim 5, characterized in that said spring (323) is a helical compression spring, which is mounted within a suitable casing (321) and/or guided in/on a suitable guide (322) and is suitable for generating a predetermined force, by which said primary actuator (32) is pressed towards the second arm (312) of said around its pivot point (310) pivotable lever (31) and which is by inactive secondary actuator (34) sufficient for providing each required friction between the brake disc (1) and the brake belt (2) and each required torque for the purpose of braking.

7. Belt brake according to anyone of Claims 1 - 4, characterized in that said primary actuator (32) is a hydraulic cylinder, which is suitable for generating a predetermined force, by which said primary actuator (32) is pressed towards the second arm (312) of said around its pivot point (310) pivotable lever (31) and which is by inactive secondary actuator (34) sufficient for providing each required friction between the brake disc (1) and the brake belt (2) and each required torque for the purpose of braking.