Tree trimmer

Abstract

A tree trimmer comprises: a trimmer body; a blade system; an electric motor (4) adapted to provide a driving force for the blade system, wherein rotation of the electric motor (4) in a first direction is adapted to provide a cutting action; a control system (5) adapted to control the electric motor (4); and a transmission system adapted to transfer power from the electric motor (4) to the blade system, the transmission system comprising a transmission rope (6). The tree trimmer comprises a tension management system (8) adapted to detect a rope slack condition in which the tension of the transmission rope (6) is below a predetermined limit value, and the control system (5) adapted to prevent rotation of the electric motor (4) in a second direction opposite the first direction in response to the detection of the rope slack condition.

Description

Technical Field

[0001] The invention relates to a tree trimmer according to the preamble of claim 1. Background Art

[0002] Document US2021 / 0076572A1 discloses a known trimmer comprising the features of the preamble of claim 1. The known trimmer comprises an electric motor connected to a trimmer body and a transmission system adapted to transmit power from the electric motor to a blade system. The transmission system comprises a rope, a screw and a nut rotatably connected to the screw.

[0003] One disadvantage associated with the above-mentioned known trimmers is that, in the event that the blade system becomes stuck for reasons associated with the cutting action, there is a risk that the cord of the transmission system becomes entangled. Summary of the invention

[0004] It is an object of the present invention to provide a tree lopper which alleviates the above mentioned disadvantages. The object of the present invention is achieved by a tree lopper as characterised in what is defined in the independent claim. Preferred embodiments of the invention are disclosed in the dependent claims.

[0005] The present invention is based on the idea of ​​providing a tree trimmer with a tension management system adapted to detect a slack rope condition in which the tension of the drive rope is below a predetermined limit value, wherein the control system is adapted to control the electric motor in response to the detection of the slack rope condition such that the risk of the drive rope becoming entangled is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention will be described in more detail below by means of preferred embodiments with reference to the accompanying drawings, in which:

[0007] Figure 1 A tree trimmer according to an embodiment of the present invention is shown;

[0008] Figure 2 Shown in another operating position Figure 1 A tree lopper in which the telescopic structure of the tree lopper is in an extended state;

[0009] Figure 3A Shown as seen from the right Figure 1 a cross-section of a first end of a tree pruner;

[0010] Figure 3B Shown as seen from the right Figure 1 a cross-section of a second end of the tree pruner;

[0011] Figure 4A Shown from above Figure 1 a cross-section of a first end of the tree pruner; and

[0012] Figure 4B Shown from above Figure 1 A cross-section of a second end of a tree lopper. DETAILED DESCRIPTION

[0013] Figure 1 A tree trimmer comprising a trimmer body and a blade system is shown. The trimmer body comprises a first body section 11 and a second body section 12 spaced apart in the longitudinal direction of the trimmer body. The blade system is connected to the first body section 11 and comprises a first blade 21 and a second blade 22 adapted to cooperate with each other to cut branches.

[0014] The first blade 21 and the second blade 22 are adapted to move relative to each other so that the blade system has a blade open position and a cutting position. Figure 1 , the blade system is in the blade open position.

[0015] The first blade 21 is fixedly connected relative to the first body section 11, and the second blade 22 is rotatably connected relative to the first body section 11. The first blade 21 and the second blade 22 are adapted to cooperate as a bypass blade for cutting branches. In an alternative embodiment, the first blade and the second blade are adapted to cooperate as an anvil blade for cutting branches.

[0016] The trimmer body has a telescopic structure so that the distance between the first body section 11 and the second body section 12 is adjustable. Figure 2 Shown in another operating position Figure 1 Tree trimmers, with Figure 1 Compared to the illustrated embodiment, in this further operating position the telescopic structure of the tree trimmer is in an extended state.

[0017] Figures 3A to 4B Shows Figure 1 A cross section of an end portion of a tree pruner. Figure 3A A cross section of the first end as seen from the right is shown. Figure 3B A cross section of the second end as seen from the right is shown. Figure 4A A cross section of the first end seen from above is shown. Figure 4B A cross section of the second end seen from above is shown.

[0018] The tree trimmer is an electric tree trimmer comprising an electric motor 4, a control system 5 adapted to control the electric motor 4, a transmission system adapted to transfer power from the electric motor 4 to the blade system, a tension management system 8 and a position detection system.

[0019] The electric motor 4 is connected to the second body section 12 and is adapted to provide a driving force for the blade system. The rotation of the electric motor 4 in a first direction is adapted to provide a cutting action in which the blade system moves from a blade opening position toward a cutting position. The battery 407 is adapted to power the electric motor 4.

[0020] The transmission system is suitable for transmitting power from the electric motor 4 to the blade system. The transmission system comprises a reduction gear 601 , a rope reel 7 , a transmission rope 6 and a transmission chain 62 .

[0021] The first end of the drive rope 6 is connected to the blade system via a drive chain 62, and the second end of the drive rope 6 is connected to the electric motor 4, such that rotation of the electric motor 4 in a first direction is adapted to pull the first end of the drive rope 6 in a longitudinal direction toward the second body section 12. In an alternative embodiment, the first end of the drive rope is directly connected to the blade system.

[0022] The blade system is adapted so that the movement of the blade system between the blade opening position and the cutting position is provided by the operating movement of the first end of the transmission rope 6. The length of the operating movement is 350 mm. In an alternative embodiment, the length of the operating movement is in the range of 100-500 mm.

[0023] The trimmer body comprises a first tube 101 and a second tube 102, such that the first tube 101 partially extends within the second tube 102, so as to provide a telescopic structure of the trimmer body. The transmission rope 6 extends within the first tube 101 and the second tube 102.

[0024] The first body section 11 is adapted to rotate relative to the second body section 12 about a rotation axis perpendicular to the longitudinal direction of the trimmer body. Figure 3A In , the rotation axis is perpendicular to the image plane, while in Figure 4A In the embodiment of the present invention, the rotation axis is vertical.

[0025] The transmission rope 6 comprises an aramid material and comprises a woven portion. The cross section of the transmission rope 6 is rectangular, so that the width of the transmission rope 6 is greater than its thickness. In one embodiment, the width of the transmission rope is greater than or equal to 300% of the thickness of the transmission rope. In an alternative embodiment, the cross section of the transmission rope is circular.

[0026] The rope reel 7 is adapted to receive a portion of the drive rope 6 around it, and the electric motor 4 is adapted to rotate the rope reel 7. Herein, the expression "drive rope" is intended to cover all flexible elongated structures that can be wound on the rope reel and are capable of transmitting power from the electric motor to the blade system. Thus, for example, the expression "drive rope" includes ropes and belts.

[0027] The tension management system 8 is communicatively connected to the control system 5 and is adapted to detect a slack rope condition in which the tension of the transmission rope 6 is below a predetermined limit value. The control system 5 is adapted to prevent the electric motor 4 from rotating in a second direction opposite to the first direction as a response to the detection of the slack rope condition. Thus, the tension management system 8 together with the control system 5 is adapted to reduce the risk of the transmission rope 6 becoming entangled.

[0028] The tension management system 8 comprises a spring loaded rope tensioner 802. The tension management system 8 is adapted to detect a rope slack condition based on the position of the spring loaded rope tensioner 802. The spring loaded tensioner may comprise a known tensioner.

[0029] The spring loaded rope tensioner 802 is adapted to receive a tensioned length section of the transmission rope 6 so that the spring loaded rope tensioner 802 can compensate for stretching having a tensioned length. The tensioned length is 30 mm. In an alternative embodiment, the tensioned length is in the range of 15-100 mm.

[0030] The tensioning length is less than or equal to 50% of the operating movement length. In an alternative embodiment, the tensioning length is less than or equal to 25% of the operating movement length.

[0031] In one embodiment, the tension management system is adapted to provide a slack rope alarm to a user of the tree trimmer in response to a detected slack rope condition. The slack rope alarm includes an audio signal and / or a visual signal.

[0032] The blade system includes a return spring 208, which is suitable for returning the blade system to the blade open position if the blade system deviates from the blade open position in the direction of the cutting position. The transmission system includes a transmission ratio between the electric motor 4 and the blade system so that the return spring 208 cannot rotate the electric motor 4 in the second direction through the transmission system.

[0033] The position detection system is adapted to detect a cutting position of the blade system, and the control system 5 is adapted to control the rotation of the electric motor 4 in response to the detection of the cutting position. In an alternative embodiment (not shown), the position detection system is adapted to detect multiple positions of the blade system, and the control system is adapted to control the rotation of the electric motor in response to the detection of multiple positions of the blade system, as described below. The multiple positions of the blade system include a blade open position and a cutting position. In another alternative embodiment, the position detection system is adapted to detect at least one position of the blade system, and the control system is adapted to control the rotation of the electric motor in response to the detection of the at least one position of the blade system.

[0034] The position detection system comprises a first positioning marking element 31 connected to the transmission rope 6 and a position sensor 37 connected to the second body section 12, such that the first positioning marking element 31 and the position sensor 37 are adapted to cooperate to detect the cutting position.

[0035] In an alternative embodiment in which the position detection system is adapted to detect multiple positions of the blade system, the position detection system includes a plurality of positioning marking elements connected to the drive rope, such that the plurality of positioning marking elements and the position sensor are adapted to cooperate to detect multiple positions of the blade system. The positioning marking elements are spaced apart from each other along the length of the drive rope.

[0036] The plurality of positioning marking elements include a first positioning marking element and a second positioning marking element. In an alternative embodiment, the position detection system includes a positioning marking element for each of a plurality of positions of the blade system detectable by the position detection system.

[0037] The first positioning marking element 31 and the position sensor 37 are adapted to cooperate to detect the cutting position. The control system 5 is adapted to stop the rotation of the electric motor 4 in the first direction in response to the detection of the cutting position. In another embodiment, the control system is adapted to stop the rotation of the electric motor in the first direction and control the electric motor to rotate in the second direction in response to the detection of the cutting position. This automatic operation is adapted to return the blade system to the blade open position after the cutting action.

[0038] The advantage of automatically stopping the rotation of the electric motor 4 in the first direction in response to the detection of the cutting position is that the automatic stop prevents harmful stress on the transmission system, the electric motor 4 and the blade system. Without the automatic stop, there would be a risk that the electric motor 4 would continue to pull the transmission rope 6 after the blade system has reached its mechanical extreme position in the cutting direction, thereby generating unnecessary stress on the transmission system, the electric motor 4 and the blade system.

[0039] The second positioning marking element and the position sensor are adapted to cooperate to detect the blade open position. The control system is adapted to stop the rotation of the electric motor in the second direction in response to the detection of the blade open position. This automatic operation is adapted to prevent an undesirable situation in which the blade system reaches its extreme position in the opening direction, but the electric motor continues to rotate in the second direction. If allowed to proceed, this undesirable situation may eventually lead to a slack rope condition.

[0040] The extreme position of the blade system in the opening direction is the blade opening position. In an alternative embodiment, the extreme position of the blade system in the opening direction is a position slightly exceeding the blade opening position.

[0041] The control system 5 comprises an operating switch 501 adapted for manual operation. The control system 5 is adapted to control the electric motor 4 to rotate in the second direction in response to the user of the tree pruner releasing his grip from the operating switch 501. This automatic operation is adapted to return the blade system to the blade open position if the user of the tree pruner stops the cutting action before the blade system reaches the cutting position.

[0042] The detection of a slack rope condition overrides all automatic and manual operations.The control system 5 is adapted to prevent the electric motor 4 from rotating in the second direction until a slack rope condition no longer exists.

[0043] A slack rope condition may be caused by a situation where the blade system is stuck so that the return spring 208 cannot return the blade system to the blade open position even when there is no tension in the drive rope 6. Removing or clearing a slack rope condition may require manually removing the cause of the stuck blade system.

[0044] The first positioning mark element 31 includes a magnet, and the position sensor 37 includes a Hall sensor.

[0045] In an alternative embodiment of the position detection system adapted to detect a plurality of positions of the blade system, each of the plurality of positioning mark elements comprises a magnet, and the position sensor comprises a Hall sensor. The position sensor comprises exactly one Hall sensor element, and the magnets of the first positioning mark element and the second positioning mark element are adapted to provide different types of magnetic fields, such that the exactly one Hall sensor element is capable of distinguishing the first positioning mark element from the second positioning mark element. In one embodiment, the directions and / or magnitudes of the magnetic fields of the magnets of the first positioning mark element and the second positioning mark element are different from each other.

[0046] In an alternative embodiment, the position sensor comprises one Hall sensor element for each of the plurality of positioning marking elements.The Hall sensor elements may be spaced apart in the longitudinal direction of the trimmer body.

[0047] It is obvious to a person skilled in the art that the concept of the invention can be implemented in various ways.The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. A tree trimmer comprising: A trimmer body, the trimmer body comprising a first body section (11) and a second body section (12) spaced apart in a longitudinal direction of the trimmer body; a blade system connected to the first body section (11), the blade system comprising a first blade (21) and a second blade (22) adapted to cooperate with each other to cut branches, wherein the first blade (21) and the second blade (22) are adapted to move relative to each other so that the blade system has a blade-open position and a cutting position; an electric motor (4) connected to the second body section (12) and adapted to provide a driving force for the blade system, wherein rotation of the electric motor (4) in a first direction is adapted to provide a cutting action in which the blade system moves from the blade open position toward the cutting position; a control system (5) adapted to control the electric motor (4); and a transmission system adapted to transmit power from the electric motor (4) to the blade system, the transmission system comprising a transmission rope (6), wherein a first end of the transmission rope (6) is connected to the blade system and a second end of the transmission rope (6) is connected to the electric motor (4), such that rotation of the electric motor (4) in the first direction is adapted to pull the first end of the transmission rope (6) in the longitudinal direction towards the second body section (12), The tree trimmer comprises a tension management system (8) adapted to detect a slack rope condition in which the tension of the drive rope (6) is below a predetermined limit value, and the control system (5) is adapted to prevent the electric motor (4) from rotating in a second direction opposite to the first direction in response to the detection of the slack rope condition.

2. A tree trimmer according to claim 1, wherein: The blade system comprises at least one return spring (208) adapted to return the blade system to the blade open position if the blade system deviates from the blade open position in the direction of the cutting position, and the transmission system has a transmission ratio between the electric motor (4) and the blade system such that the at least one return spring (208) cannot cause the electric motor (4) to rotate in the second direction via the transmission system.

3. A tree trimmer according to claim 1 or 2, wherein: The tree trimmer comprises a position detection system adapted to detect the cutting position, and the control system (5) is adapted to control the electric motor (4) to rotate in the second direction in response to the detected cutting position.

4. A tree trimmer according to any one of claims 1 to 3, wherein: The control system (5) comprises an operating switch (501) adapted for manual operation, wherein the control system (5) is adapted to control the electric motor (4) to rotate in the second direction in response to a condition in which a user of the tree trimmer releases his grip from the operating switch (501).

5. A tree trimmer according to any one of the preceding claims, wherein: The transmission system comprises a rope reel (7) adapted to receive a portion of the transmission rope (6) around the rope reel, and the electric motor (4) is adapted to rotate the rope reel (7).

6. A tree trimmer according to any one of the preceding claims, wherein: The tension management system (8) comprises at least one spring-loaded rope tensioner (802), wherein the tension management system (8) is adapted to detect a rope slack condition based on a position of the at least one spring-loaded rope tensioner (802).

7. A tree trimmer according to any one of the preceding claims, wherein: The first blade (21) is fixedly connected relative to the first body section (11), and the second blade (22) is rotatably connected relative to the first body section (11), wherein the first blade (21) and the second blade (22) are adapted to cooperate as a bypass blade for cutting branches.

8. A tree trimmer according to any one of the preceding claims, wherein: The first body section (11) is adapted to rotate relative to the second body section (12) about a rotation axis perpendicular to the longitudinal direction of the trimmer body.

9. A tree trimmer according to any one of the preceding claims, wherein: The trimmer body comprises at least one tube, and the transmission cord (6) extends within the at least one tube.

10. A tree trimmer according to any preceding claim, wherein: The trimmer body has a telescopic structure, so that the distance between the first body section (11) and the second body section (12) is adjustable.

11. A tree trimmer according to any preceding claim, wherein: The transmission rope (6) comprises at least one woven portion.

12. A tree trimmer according to any preceding claim, wherein: The transmission rope (6) comprises aramid material.

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