Apparatus for delimbing living trees

Abstract

The invention relates to an apparatus for delimbing living trees (1), comprising a running-gear frame (2) which has a motor-driven wheeled running gear (3), a motor-driven cutting tool (4), and an electronic controller (5) which interconnects the motor drives of the wheeled running gear (3) and the cutting tool (4). The wheeled running gear (3) is characterised in that it has at least three wheels (9, 10, 11) running on wheel suspensions (6, 7, 8), and the wheels (9, 10, 11) each have a steering axle intersecting their wheel axles, wherein the wheel contact points of the wheels (9, 10, 10, 11) are arranged on a common circular line.

Description

[0001] Device for delimbing living trees

[0002] The invention relates to a device for delimbing living trees with a chassis frame which has a motor-driven wheel chassis, a motor-driven cutting tool and an electronic control system connecting the motor drives of the wheel chassis and cutting tool, wherein the wheel chassis has at least three wheels running on wheel suspensions, and the wheels each have a steering axle crossing their wheel axles.

[0003] The Japanese company "e-Valley" developed a similar climbing saw whose chainsaw blade is powered by a lightweight electric motor. The German patent DE 10 2021 126 567 B3 describes a device for limbing living trees, comprising a motor-driven wheeled chassis mounted on a helical climbing track and at least one cutting tool with a power transducer. A contactless branch detection sensor is arranged on the wheeled chassis and connected to the motor drives of the wheeled chassis and the cutting tool via a control unit. The steering axles allow the gradient of the helical climbing track to be continuously changed, in particular adapted to the respective climbing track diameter, thus accelerating the approach to the branch bases of the branches to be cut off from living trees.Variable climbing track diameters result from variable trunk circumferences, where the vertical advance of the cutting tool can only be maintained at a constant travel speed of the wheeled chassis if the gradient of the helical climbing track is increased or decreased accordingly. To adjust the gradient of the helical climbing track, the wheeled chassis, which travels up the trunk of the tree to be delimbed, is directionally steered via the steering axles.

[0004] The invention is based on the object of demonstrating a device of the type mentioned at the outset which enables particularly efficient and yet gentle delimbing of a tree population.

[0005] This object is achieved according to the invention by a device having the features of patent claim 1. Advantageous developments of the invention are specified in the subclaims.

[0006] The device according to the invention for trimming living trees is characterized in that the wheel contact points of the wheels are arranged on a common circular line. This creates a structurally extremely simple wheeled chassis in which the weight of the entire device is transmitted with static certainty via the three wheel suspensions into the trunk of a tree being traveled over by the device according to the invention. With this minimalist design of the wheeled chassis, the weight of the device according to the invention is reduced to a minimum, so that its use is also possible during the trees' growth period without risking damage to their sensitive cambium layers. Furthermore, the low weight of the device according to the invention can be used to accommodate more powerful batteries, so that the number of operating hours achievable with a single battery charge can be advantageously increased.The wheel contact points defined within the scope of this invention are the points of contact between the wheels and the upwardly extending trunk of a living tree. In order to reliably transfer the weight force acting on the device according to the invention into the trunk of a tree, additional clamping forces are required at the wheel contact points, with which the tree trunk can be clamped between the three wheels, similar to a three-jaw chuck. In its working position, the wheeled chassis preferably enables the device according to the invention to ascend along a helical climbing path, on which branches in the path of the device are severed with the cutting tool. For this purpose, the cutting tool preferably has pruning shears and a pivoting arm guiding the pruning shears. The motor drives of the cutting tool are finally integral components of the actuating mechanisms for the pruning shears and the pivoting arm.

[0007] According to a first development of the device according to the invention, the chassis frame is composed of at least two frame parts, each frame part having a linear guide in which at least one of the wheel suspensions is movably accommodated. The linear guides enable the wheel chassis to increase or decrease the wheel center distances of its wheels and thus to adjust the diameter of the circular line passing through the wheel contact points to the trunk diameter of the delimbed tree or tree still to be delimbed. Preferably, the motor drives of the wheel chassis have actuators acting on the wheel suspensions, with which the wheels can be moved selectively against the trunk of a tree to be delimbed, into a working position, or into a change position that releases the tree trunk.In principle, however, it is within the scope of the invention if adjusting the axle spacing to the diameter of a tree trunk to be traveled over merely requires manually moving the wheels toward the tree trunk. If the wheeled chassis has more than three wheels mounted on wheel suspensions, more than two linear guides are required for diameter adjustment.

[0008] According to a further development of the invention, the frame parts are connected to one another via a pivot joint, wherein the chassis frame has a ring closure formed between the frame parts at a distance from the pivot joint. The pivot joint enables the chassis frame, which is open at the ring closure, to be widened in order to attach the wheeled chassis to the tree trunk of a tree to be delimbed or to remove it from the tree trunk again. The ring closure represents, in particular, a safety measure that reliably prevents the device according to the invention from falling off a tree trunk should the wheels of the wheeled chassis lose contact with the tree trunk. Alternatively, it is proposed to design one of the frame parts as a bow-like sliding bar, which, as a closure part, is held in a guide slot formed on the chassis frame.

[0009] In its working position, the chassis frame forms an angle of exactly 60° between the two linear guides, forming an isosceles triangle between the wheel contact points. If the wheel suspensions are moved outward or inward by equal distances in the linear guides of the frame sections, the isosceles triangle remains intact regardless of the resulting wheelbase between the wheels.

[0010] For motorized movement of the wheel suspensions in the linear guides, it is advantageous if the wheel suspensions each run on a threaded spindle driven by an electric motor. The self-locking characteristic of threaded spindles and the high gear ratios achievable with threaded spindles are particularly beneficial for the installation of weaker and thus advantageously lighter electric drives. If the wheel chassis has more than three wheels running on wheel suspensions, the wheel suspensions held in the linear guides can, for example, run on the flat spiral of a chuck gear. The flat spiral then consists of at least two flat spiral ring segments, each of which is arranged on one of the pivotally connected frame parts.The segmented design of the plan spiral allows the chassis frame to be opened and closed in order to be able to attach it to the trunk of a tree to be delimbed or to be able to remove it from a delimbed trunk.

[0011] To prevent the wheeled chassis from jamming on the trunk of a tree being trimmed, the wheel contact points and the circular line connecting them must be kept as horizontal as possible. For this purpose, the motorized drives of the wheeled chassis feature independent wheel steering on the steering axles, allowing the control system to compensate for even the smallest inclinations.

[0012] To compensate for unevenness, such as stumps, cracks in the bark, or hollows in the trunk that lie in the wheel tracks, a suspension spring is arranged in the wheel suspensions of at least two wheels. The wheel suspensions containing the suspension springs are preferably those wheel suspensions that are accommodated in the linear guides of the frame parts. An acute angle of preferably 30° is formed between the travel of the linear guide and the spring travel of the associated suspension spring.

[0013] For automatic centering of the chassis frame on the trunk of a tree being traveled over with the device according to the invention, a further development of the invention provides for the chassis springs to each have a non-linear spring stiffness. Such chassis springs are preferably tension springs with helically wound spring wire, as these are particularly suitable for creating large spring travels with non-linear spring stiffness.

[0014] In order to minimize the loads on the cambium layer of a tree trunk being traveled over with the device according to the invention, the motor drives of the wheeled chassis have wheel hub motors assigned to each wheel. Thus, the drive power of the device according to the invention can be advantageously distributed across three wheel contact points and introduced into the tree trunk, further minimizing the risk of damaging the cambium layer.

[0015] According to a particularly advantageous development of the invention, the wheel hub motors each have their own speed controller, whereby the speed controllers are interconnected via the control system. Because the wheel hub motors can be controlled independently of one another in terms of their speeds, there is advantageously the possibility of kinematically securing the wheeled chassis to the trunk of a tree being traveled over. For this purpose, a speed curve is defined in the control system for the third wheel on the wheeled chassis, which runs between the two movably held wheels. This speed curve lies between a higher speed curve of the wheel leading it and a lower speed curve of the wheel trailing it. At such speed ratios, the wheeled chassis automatically grips the tree trunk it is traveling over.

[0016] An alternative to designing the wheel hub motors with a single speed controller is to have the wheel hub motors share a common speed controller and have the wheels with different tread diameters. In this embodiment, the kinematically determined securing of the wheeled chassis to the trunk of the tree being traveled over can be achieved by having the third wheel, which runs on the wheeled chassis between the two adjustable wheels, have a tread diameter that lies between a larger tread diameter of the wheel leading it and a smaller tread diameter of the wheel trailing it.

[0017] To detect a tilt angle in which the circular line connecting the wheel contact points is tilted out of a horizontal plane, the chassis frame has at least one tilt sensor connected to the motor drives of the wheel chassis via the control system. The tilt sensor is preferably an electrical measuring device that establishes a precise reference to the direction of gravitational acceleration and thus monitors the tilt angle of the chassis frame.

[0018] According to another development of the invention, the cutting tool is assigned at least one branch detection sensor located on the chassis frame, which is connected to the motor drives of the wheeled chassis and the cutting tool via the control system. The contactless branch detection sensor enables contactless measurement of the branches to be cut by collecting position data. The control system, in turn, evaluates this position data to determine branch arrangements, branch thicknesses, and branch positions, as well as to generate control commands for controlling the motor drives of the wheeled chassis and the cutting tool. The contactless and thus early evaluation of the position data ensures particularly reliable and therefore trouble-free delimbing of living trees.

[0019] The operational reliability of the device according to the invention is further improved by the fact that the cutting tool has at least one contact switch, which is connected to the motor drive of the cutting tool via the controller. With the contact switch, the motor drive associated with the cutting tool is advantageously only activated when the cutting tool has mechanically grasped a branch to be severed in a predetermined manner. In the case of a cutting tool designed as a classic pair of pruning shears with a cutting edge and counter-cutting edge, such mechanical branch grasping is the catching of the branch to be severed with the shear jaws.

[0020] An embodiment of the invention, from which further inventive features emerge, is shown in the drawing. Figure 1 shows a first perspective view of an inventive

[0021] Device for delimbing a living tree;

[0022] Figure 2: a second perspective view of the device according to

[0023] Figure 1 ; and

[0024] Figure 3: a detailed view of a wheel suspension movably mounted in a linear guide for a device according to Figures 1 and 2.

[0025] Figures 1 and 2 show different perspective views of a device according to the invention during the limbing of a living tree 1. The device has a chassis frame 2, which has a motor-driven wheeled chassis 3, a motor-driven cutting tool 4, and an electronic control system 5 connecting the motor drives of the wheeled chassis 3 and cutting tool 4. The wheeled chassis 3 has three wheels 9, 10, 11 running on wheel suspensions 6, 7, 8, the wheel contact points of which are arranged on a common circular line. The chassis frame 2 is composed of two frame parts 12, 13, each frame part 12, 13 having a linear guide 14, 15 in which one of the wheel suspensions 6, 7 is adjustably received. The frame parts 12, 13 are connected to one another via a pivot joint 16, the pivot axis of which runs through the length of the frame profile.The chassis frame 2 has a ring lock 17 formed at a distance from the pivot joint 16 between the frame parts 12, 13. The figures show the chassis frame 2 in a working position in which an angle of 60° is formed between the two linear guides 14, 15 and an isosceles triangle is formed between the wheel contact points. The cutting tool 4 has a pair of pruning shears 18, a pivot arm 19 guiding the pruning shears 18, and a contact switch 20, which is connected to the motor drives 21 of the cutting tool 4 via the control system 5. Two carrying handles 22, 23 attached to the frame parts 12, 13 are arranged in a plane that vertically passes through the center of gravity of the device according to the invention.

[0026] Figure 3 shows a detailed view of a wheel suspension movably mounted in a linear guide for a device according to Figures 1 and 2. The detailed view shows that the linear guides 14, 15 each have an electric motor 24, 25 with a threaded spindle 26, 27. The wheels 9, 10, 11 each have a steering axis crossing their wheel axles. The motor drives of the wheel chassis 3 have independent wheel steering assemblies 28, 29, 30 formed on the steering axis of the wheels 9, 10, 11. The wheels 9, 10 have chassis springs 31, 32 arranged in their wheel suspensions 6, 7. In addition, the motor drives of the wheel chassis 3 have three wheel hub motors 33, 34, 35, each assigned to one of the wheels 9, 10, 11. Identical components are provided with the same reference numbers.

Claims

AMENDED CLAIMS received by the International Bureau on 15 July 2025 (15.07.2025) 1. Device for delimbing living trees, with a chassis frame which has a motor-driven wheel chassis, a motor-driven cutting tool and an electronic control unit connecting the motor drives of the wheel chassis and cutting tool, wherein the wheel chassis (3) has at least three wheels (9, 10, 11) running on wheel suspensions (6, 7, 8), and the wheels (9, 10, 11) each have a steering axle crossing their wheel axes, wherein the wheel contact points of the wheels (9, 10, 11) are arranged on a common circular line, and the motor drives of the wheel chassis (3) have wheel hub motors (33, 34, 35) respectively assigned to the wheels (9, 10, 11), characterized in that the wheel hub motors (33, 34, 35)34, 35) each have their own speed controller, that the speed controllers are interconnected via the control (5), and that for the third wheel (11) running on the wheel chassis (3) between the two movably held wheels (9, 10), a speed curve is defined in the control (5), which lies between a higher speed curve of the wheel (9 or 10) leading it and a lower speed curve of the wheel (10 or 9) trailing it.

2. Device for cutting living trees, with a chassis frame which has a motor-driven wheel chassis, a motor-driven cutting tool and an electronic control system connecting the motor drives of the wheel chassis and the cutting tool, wherein the wheel chassis (3) has at least three wheels (9, 10, 11) running on wheel suspensions (6, 7, 8), and the wheels (9, 10, 11) each have a steering axle crossing their wheel axles, wherein the wheel contact points of the wheels (9, 10, 11) are arranged on a common circular line, and the motor drives of the wheel chassis (3) Wheels (9, 10, 11) each have associated wheel hub motors (33, 34, 35), characterized in that the wheel hub motors (33, 34, 35) have a common speed controller, that the wheels (9, 10, 11) have different tread diameters, and that the third wheel (11) running on the wheel chassis (3) between the two rigidly movable wheels (9, 10) has a tread diameter which lies between a larger tread diameter of the wheel (9 or 10) leading it and a smaller tread diameter of the wheel (10 or 9) trailing it.

3. Device according to claim 1 or 2, characterized in that the chassis frame (2) is composed of at least two frame parts (12, 13), each frame part (12, 13) having a linear guide (14, 15) in which at least one of the wheel suspensions (6, 7, 8) is accommodated in an adjustable manner.

4. Device according to claim 3, characterized in that the frame parts (12, 13) are connected to one another via a pivot joint (16), and in that the chassis frame (2) has a ring closure (17) formed at a distance from the pivot joint (16) between the frame parts (12, 13).

5. Device according to claim 3 or 4, characterized in that the chassis frame (2) has a working position in which an angle of 60° is formed between the two linear guides (14, 15) and an isosceles triangle is formed between the wheel contact points.

6. Device according to claim 5, characterized in that the Wheel suspensions (6, 7, 8) held by linear guides (14, 15) are each a threaded spindle (26, 27) which is driven by an electric motor (24, 25).

7. Device according to one of claims 1 to 6, characterized in that the motor drives of the wheel chassis (3) have individual wheel steering systems (28, 29, 30) formed on the steering axles of the wheels (9, 10, 11).

8. Device according to one of claims 1 to 7, characterized in that a chassis spring (31, 32) is arranged in each of the wheel suspensions (6, 7) of at least two wheels (9, 10).

9. Device according to one of claims 1 to 8, characterized in that the chassis springs (31, 32) each have a non-linear spring stiffness.

10. Device according to one of claims 1 to 9, characterized in that the chassis frame (2) has at least one inclination sensor which is connected via the control (5) to the motor drives of the wheel chassis (3) 11. Device according to one of claims 1 to 10, characterized in that the cutting tool (4) is assigned at least one branch detection sensor arranged on the chassis frame (2), which is connected to the motor drives of the wheel chassis (3) via the control (5).

12. Device according to one of claims 1 to 11, characterized in that the separating tool (4) has at least one contact switch (20) which is connected to the motor drives (21) of the separating tool (4) via the control (5).

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