A forestry winch comprising chain drive and an assembly for regulating traction force of the forestry winch

Abstract

The present invention belongs to the field of forestry winches, more specifically to the field of structural elements for pulling loads. The invention relates to a forestry winch comprising chain drive and an assembly for regulating traction force of the forestry winch. The forestry winch is equipped with an assembly for regulating the traction force of the forestry winch, which comprises a pushing cylinder of a clutch that presses on the clutch or a sprocket, respectively, that presses on the clutch lamellae to transmit the torque. The essence of the invention is that the pressure in the pushing cylinder is adjusted depending on the amount of rope wound on the drum (1). In case more wire rope is wound on the drum (1), the pressure in the pushing cylinder is higher. Consequently, the pushing cylinder will press harder on the sprocket, which is driven by the chain, the sprocket will then press on the lamellae between the sprocket and the drum (1) and thus transmit torque. When the diameter decreases as the rope unwinds from the drum (1), the pressure in the pushing cylinder decreases.

Description

Field of the invention

[0001] The present invention belongs to the field of forestry winches, more specifically to the field of structural elements for pulling loads. The invention relates to a forestry winch comprising chain drive and an assembly for regulating traction force of the forestry winch.Background of the invention and the technical problem

[0002] A winch is a mechanical device used to pull a load, which is achieved by winding a rope onto the winch drum. It can be used in many fields, but is particularly important in forestry, where it is mainly used to pull logs.

[0003] As is known in this field, a forestry winch is connected to a tractor via a PTO shaft, which transmits power to the winch for the operation of the winch. The power provided by the PTO shaft is transmitted to the main sprocket via a chain system. The winch traction is activated when the push cylinder pushes the sprocket and clutches towards the drum. Due to the lining on the clutches, the rotational movement is transmitted to the drum, which consequently starts to rotate and thus wind the wire rope. The traction force of the winch is adjusted by regulating the force in the push cylinder, which always presses with the same force according to the selected traction force, as a result of which the pressure in the push cylinder is constant, regardless of whether the winding drum was full or empty.

[0004] The condition of the drum or the amount of the rope wound on the drum has a significant impact on the pulling force, as the pulling force decreases with increasing drum diameter. In practice, this means that the more wire rope is wound on the drum, the lower the pulling force of the winch. Thus, up to 50% loss of pulling force with a full drum can be recorded.

[0005] The technical problem solved by the present invention is designing a forestry winch and / or assembly that would prevent pulling force decrease when the drum is full. Maintaining or regulating the pulling force regardless of the condition of the drum would importantly affect the operation of the machine, as well as the efficiency of work with winches.Stanje tehnike

[0006] Patent EP3093264 discloses a mechanic-hydraulic system with a pressure regulator for maintaining a constant tractive force of a winch, characterized in that a pushing cylinder is pushed away with each new layer of a towing rope on a winch drum, wherein the cylinder rotates the axis of forks, which carry the pushing cylinder; that rotation of the forks' axis causes movement of a pole, which pushes a piston of a pressure regulator for one step, consequently causing an increase in oil pressure, which causes an increase of the cylinder piston pressure on couplings, resulting in an increase of the drum momentum; that distances »e«, »f« and »g« change with each movement of the pushing cylinder or the forks' axis due to a new layer of the towing rope on the drum, resulting in closing or opening of the pressure regulator with movable part of attachments, which consequently increases or decreases oil pressure in the hydraulic system; that in accordance with changes in distances »e«, »f« and »g« and directly connected forks of the pushing cylinder, a spring and the pole, an almost constant tractive force of the winch is maintained.

[0007] Patent application EP4429995 relates to a system for ensuring a constant tractive force of a winch. The essence of the invention is in that for ensuring a constant tractive force of a winch a pushing cylinder is provided for pushing onto a drum or a tube of the drum, on which a rope is wound, wherein said pushing cylinder is mounted on a holder, which is via an axis rotatably mounted on a housing of the winch. The pushing cylinder is arranged to rotate and shift away during layer-wise winding of the rope onto the drum, until the drum is fully wound. The cylinder is connected to a Hall angle sensor, which detects the angle of the cylinder and / or its holder on the housing of the winch, preferably the permanent magnet rotates with the axis and the holder of the cylinder and thus measures the angle of the pushing cylinder, wherein the semiconductor microcircuit detects the magnetic field during magnet rotation. The current position of the cylinder based on information from the Hall sensor is read by a controller and based on the measured value adjust the pressure sensor via suitable electrical signal in order to change the pressure of the winch coupling.

[0008] Both of the above-mentioned solutions relate to professional winches driven by gear transmission or worm drives, which is different from the present invention. In addition, the purpose is also different, since in both documents a constant (equal) pulling force is maintained regardless of the amount of wire rope wound on the drum, while in the present invention the pulling force is adjusted according to the diameter of the drum. The provision of the latter differs from the known solutions.Description of the solution to the technical problem

[0009] The present invention solves the problems of known solutions discussed above, i.e. winches with chain drive, the pulling force of which decreases with increasing drum diameter. The technical problem is solved as defined in the independent claim, wherein preferred embodiments described in the dependent claims.

[0010] A forestry winch with a chain drive for transmitting power from the tractor via the PTO shaft is equipped with an assembly for regulating the traction force of the forestry winch, which comprises a pushing cylinder of a clutch that presses on the clutch or a sprocket, respectively, that presses on the clutch lamellae to transmit the torque. Previously known solutions of forestry winches with a chain drive have a constant pressure on the clutch pushing cylinder, so the clutch pushing cylinder always presses on the clutch or the sprocket with the same force. The essence of the invention is that the pressure in the pushing cylinder is adjusted depending on the amount of rope wound on the drum. In case more wire rope is wound on the drum (i.e. the diameter of the drum is larger), the pressure in the pushing cylinder is higher. Consequently, the pushing cylinder will press harder on the sprocket, which is driven by the chain, the sprocket will then press on the lamellae between the sprocket and the drum and thus transmit torque. When the diameter decreases as the rope unwinds from the drum, the pressure in the pushing cylinder decreases.

[0011] To detect the diameter of the drum or the amount of rope wound on the drum, the winch is equipped with a pressing roller, which presses the rope against the drum during winding or unwinding. In this working process, it always performs a movement that is directly proportional to the winding and unwinding of the wire rope onto or from the drum. Depending on the number of coils of the rope, the pressing roller can be more or less distant, and its position can be detected by any suitable element arranged to detect position. In a preferred embodiment, the pressing roller is connected to a toothed rack and a gear, through which the angle of the pressing roller or the distance to the pressing roller is measured with a suitable sensor. The said sensor can be installed in any position where it can detect a change in the distance or angle of the pressing roller or the winding of the rope on the drum. The sensor for reading the position of the pressing roller can be an angle meter or angle sensor, an optical or laser sensor, a string sensor, an inductive sensor, a Hall sensor (magnetic), an ultrasonic sensor, a radar sensor or any measuring element that can measure change, wherein an angle sensor is preferred.

[0012] To monitor the changes in the diameter of the drum, the forestry winch is therefore preferably equipped with the toothed rack and a gear as well as an angle sensor. The diameter is read via the pressing roller, which is mounted at the bottom of the winch. The movement of the pressing roller is transmitted via the toothed rack and the gear to an angle sensor, which can be placed anywhere where it can detect a change in the rope winding. The said angle sensor or other suitable sensor can be placed above, below or next to the movable mechanism, which performs a certain movement depending on the position of the pushing cylinder.

[0013] The information from the sensor is sent to the controller, which in turn controls the proportional valve for opening or closing the clutch pushing cylinder, in which the working pressure is consequently changed. In the preferred embodiment, in which the angle sensor is used, the working pressure increases as the angle increases, and decreases as the angle decreases, or vice versa, depending on the installation of the sensor and the programming of the controller. Both solutions are equivalent and functional. In the preferred embodiments, the relationship between the increase in angle degrees and the working pressure or the decrease in angle degrees and the working pressure is linear. Thus, the regulation of the pulling force is ensured when the drum of a single-drum forestry winch with chain transmission is full. The pulling force of the winch is therefore set by regulating the pressure in the clutch pushing cylinder.

[0014] During manufacture and adjustment, the pressure is set according to the power of the winch, which allows the winch to pull with the desired power. For example, in a 6-ton winch, the pressure is set to 110 bar during assembly, so that with an empty drum the winch will pull with 6 tons. This is a preset value that neither the computer nor the user can reset, because this is not allowed by law. The pressure range is then divided according to the size of the drum, as well as the diameter of the pulling rope. When the range is divided into percentages, for each change in the diameter of the drum due to the wound rope, the pressure is then increased by the appropriate percentage, thereby maintaining the pulling force, which is in the above example 6 tons. Since each winch has its own drum diameter and its own pulling rope diameter, each winch must have the controller and its settings adapted to the dimensions of the drum and rope.

[0015] The invention successfully prevents a drop in traction force when the drum is full. Maintaining or regulating traction force regardless of the drum condition also improves machine operation and winch efficiency.

[0016] The forestry winch comprising chain drive and an assembly for regulating traction force of the forestry winch according to the invention will be described in further detail based on an exemplary embodiment and figures, which show: Figure 1 The preferred embodiment of the drum with the pressing roller, the toothed rack and the gear, which transmit information about the position of the pressing roller to the sensor Figure 2 A shematic representation of information travelling from the position of the pressing roller to the change in the pressure in the pushing cylinder of the clutch

[0017] The forestry winch according to the invention comprises: a housing, inside which a drum 1 for winding and unwinding the pulling rope is installed, the pulling rope, which is wound or unwound from the drum via a pulley, a chain transmission for transmitting the drive to the drum 1 from the tractor, a clutch with a sprocket adapted for pressure on the clutch lamellaee, a pushing cylinder of the clutch, configured to apply pressure on the sprocket, a valve for regulating the pushing cylinder of the clutch or the pressure in the said pushing cylinder, respectively, a controller for adjusting the operation of the forestry winch with the valve, a system for detecting the diameter of the drum 1 or the amount of wound rope, which according to a preferred embodiment, as also shown in the figures, comprises a pressing roller 2, which presses the pulling rope onto the drum 1 during winding or unwinding, and a toothed rack 3 connected to the pressing roller 2, a gear 4 connected to the toothed rack 3, and an angle sensor 5 configured for detecting the angle of the pressing roller 2.

[0018] Figure 1 shows the system for detecting drum diameter, wherein the pressing roller 2 is attached in the bottom of the winch, and the movement of the pressing roller 2 is through the toothed rack 3 and the gear 4 transmitted to the angle sensor 5, which is installed next to the movable mechanism comprising the toothed rack 3 and the gear 4, wherein the mentioned movable mechanism performs a particular movement depending on the position of the pushing cylinder.

[0019] As shown in figure 2, which is a simple shematic representation of information travelling from the position of the pressing roller to the change in the pressure in the pushing cylinder of the clutch, the angle sensor 5 detects the position of the pressing roller 2 (step A), the controller then reads the value of the angle sensor 5 in step B and suitably processes this analogue signal. Then, the controller processes the input signal in step C and sends a suitable output signal to the proportional valve. The latter controlls the pushing cylinder of the clutch with opening and closing said valve (step D), while the pressure is changed to the caluclated values based on the winch power. Due to the setting shown in figure 1, increase in the angle degrees result in the increase of the working pressure, while a decrease in the angle degrees causes the working pressure to deacrease. The pressure in the pushing cylinder is thus adjusted based on the amount or capacity of the pulling rope wound on the drum in step E. In cases where more wire rope is wound on the drum (i.e. the larger the drum diameter is), the pressure in the pushing cylinder of the clutch is higher. Consequently, the pushing cylinder of the clutch will press harder to the sprocket, which is driven with the chain, and the sprocket will then press on the lamellae located between the sprocket and the drum and thus transfer higher torque.

Claims

1. A forestry winch with a chain drive and an assembly for regulation of pulling force of the forestry winch, wherein the forestry winch comprises: - a housing, inside which a drum for winding and unwinding a pulling rope is installed, - the pulling rope, which is wound or unwound from the drum via a pulley, - a chain transmission for transmitting drive from a tractor to the drum, - a clutch with a sprocket adapted for pressing on lamellae of the clutch, - a pushing cylinder of the clutch, configured to apply pressure on the sprocket, - a valve for regulating the pushing cylinder of the clutch or the pressure in the said pushing cylinder, respectively, - a controller for adjusting the operation of the forestry winch with the valve, characterized in that the pressure in the pushing cylinder of the clutch is adjusted with the controller of the winch based on the state of the rope wound on the drum, which is detected with a system for detecting the diameter of the drum or the amount of wound rope.

2. The forestry winch according to claim 1, wherein the pressure in the pushing cylinder of the clutch increases with the increase of the wound rope on the drum of the forestry winch, while the pressure in the pushing cylinder of the clutch decreases when the diameter decreases due to unwinding of the rope from the drum.

3. The forestry winch according to claim 2, wherein the relationship between the increase of angle degree and the working pressure or the decrease of angle degree and the working pressure is linear.

4. The forestry winch according to any of the preceding claims, wherein the system for detecting drum diameter or the amount of wound drum comprises a pressing roller, which during winding or unwinding pushes the pulling rope onto the drum, wherein based on the number of coils of the pulling rope the pressing roller may be more or less distanced, wherein the position of the pressing roller is detected using any suitable element or sensor for detecting position.

5. The forestry winch according to any of the preceding claims, wherein the sensor is connected to the controller so that the status or information is sent from the sensor to the controller, which is configured to control a proportional valve for opening or closing the pushing cylinder of the clutch based on the sensed data, so that working pressure in the pushing cylinder is changed.

6. The forestry winch according to claim 4 or 5, wherein the said sensor is an angle measuring device or an angle sensor, an optical or a laser sensor, a string sensor, an inductive sensor, a Hall sensor (magnetic), an ultrasonic sensor, a radar sensor or any measuring element that can measure change.

7. The forestry winch according to any claim from 4 to 6, wherein the sensor is installed in any position where it can detect a change in the distance or angle of the pushing cylinder or the winding of the rope on the drum.

8. The forestry winch according to any claim from 4 to 7, wherein the pressing roller is connected a toothed rack and a gear, through which the angle of the pressing roller or the distance to the pressing roller is measured with the suitable sensor.

9. The forestry winch according to the preceding claim, wherein the sensor for reading the position of the pressing roller is an angle sensor and is installed above, under or next to the movable mechanism of the toothed rack and the gear, which perform movement in dependance from the position of the pressing roller.

10. The forestry winch according to the preceding claim, wherein the working pressure increases as the angle increases, and the working pressure decreases as the angle decreases, or vice versa, depending on the installation of the sensor.

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