WOOD HARVESTING DEVICE

Description

[0001] The invention relates to a device for harvesting timber with a hydraulically controlled felling head that can be attached to the boom arm of a vehicle and comprises a grapple and saw unit as well as a tilting device, wherein the grapple and saw unit has at least one pair of grapples for the harvested material, actuated by a first hydraulic cylinder, consisting of two grapple arms pivotable between an open and closed state, and a cutting element pivotable by a second hydraulic cylinder for cutting the harvested material, and is pivotable from a storage position to a cutting position for the harvested material by means of the tilting device actuated by a third hydraulic cylinder, wherein the first hydraulic cylinder is connected to a first hydraulic line for opening the grapple arms and to a second hydraulic line for closing the grapple arms, according to the preamble of claim 1.

[0002] A device of this type was described in WO 2011 / 078673 A1. Further devices for timber harvesting were described in IT 2018 000 7247 A1, EP 3097772 A1, and CA 2650748 A1. Devices of this type are used for timber harvesting, whereby an operator controls a boom arm from the vehicle such that gripper arms arranged on a grapple and saw unit grasp the harvested material, such as a tree trunk. Subsequently, via a corresponding hydraulic system, a closing pressure is exerted on the gripper arms through the aforementioned second hydraulic line and a first hydraulic cylinder. The gripper arms then fix the tree trunk relative to the boom arm with a pincer-like movement. After the tree trunk is fixed, the cutting element can be pivoted by means of a second hydraulic cylinder to cut the tree trunk.The cutting element is designed as a chainsaw and is typically pivotally mounted in a saw housing. It is operated by a hydraulic motor located within the saw housing and can be pivoted out of the housing by means of a hydraulically actuated swivel drive to cut through a log held by the grapple arms in an area below the grapple arms. After the log has been cut, the grapple and saw unit can be pivoted using the tilting device so that the grapple arms are moved from their cutting position, in which they are essentially horizontally oriented and their pivot axes are correspondingly vertical, to a storage position, in which they are essentially vertically oriented and their pivot axes are correspondingly horizontal.The severed log can then be carefully lowered by controlling the boom arm. The grapple arms are opened via the first hydraulic line mentioned earlier and a corresponding return movement of the first hydraulic cylinder to release the log. Using the third hydraulic cylinder and the tilting mechanism, the grapple and saw unit can be returned from its lowered position to its cutting position.

[0003] The hydraulically actuated processes of gripping and cutting, as well as opening the gripper and pivoting the tilting device, are typically implemented using pressure sequence controls. A hydraulic sequencing valve, operating via the same hydraulic line, handles both the closing of the gripper and, after the gripper is fully closed, the activation and pivoting of the cutting element. A second hydraulic sequencing valve, operating via a separate hydraulic line in the storage position, handles both the opening of the gripper and, after the gripper is fully open, the actuation of the tilting device to pivot the gripper and saw unit into its cutting position.A hydraulic valve switches between the two hydraulic lines. However, at least one hydraulic line must maintain a connection to the hydraulic fluid tank when not in use to allow the cutting element to retract after cutting. This connection to the hydraulic fluid tank means that after the grapple is fully opened and the tilting mechanism is activated, it will drop back down due to gravity when switching to the unpowered position (for example, to position the felling head on the crop). This makes precise positioning on the crop more difficult, which proves to be a disadvantage in operation.

[0004] The aim of the invention is therefore to realize a device for timber harvesting with a hydraulically controlled felling head that avoids this disadvantage and allows the cutting position of the gripper and saw unit to be fixed during positioning on the harvested material.

[0005] These objectives are achieved by the features of claim 1. Claim 1 relates to a timber harvesting device with a hydraulically controlled felling head that can be attached to the boom arm of a vehicle and comprises a grapple and saw unit as well as a tilting device, wherein the grapple and saw unit has at least one pair of grapples for the harvested material, actuated by a first hydraulic cylinder and consisting of two gripper arms pivotable between an open and closed state, and a cutting element pivotable by a second hydraulic cylinder for cutting the harvested material, and is pivotable from a storage position to a cutting position for the harvested material by means of the tilting device actuated by a third hydraulic cylinder.wherein the first hydraulic cylinder is connected to a first hydraulic line for opening the gripper arms and to a second hydraulic line for closing the gripper arms. According to the invention, it is proposed that a first hydraulic valve equipped with a check valve is provided, which is connected on the inlet side to the first hydraulic line and on the outlet side to a second hydraulic valve, which is connected to the third hydraulic cylinder, designed as a single-acting hydraulic cylinder, and to a third hydraulic valve, via which the second hydraulic valve is connected to the first hydraulic line, wherein the third hydraulic valve is designed to close when the first hydraulic line is pressurized and to open when the second hydraulic line is pressurized.and the second hydraulic valve is designed to direct hydraulic fluid from the first hydraulic valve to the third hydraulic cylinder when a switch is actuated by the gripper arms pivoted into their open position, and to direct hydraulic fluid from the third hydraulic cylinder to the third hydraulic valve when the gripper arms are closed without actuating the switch.

[0006] If the gripper is to be opened, the first hydraulic cylinder is actuated by means of the first hydraulic line, and the gripper opens. Hydraulic fluid is directed from the first hydraulic line to the second hydraulic valve via the first hydraulic valve, which initially remains closed because it is only opened by actuating the switch. Hydraulic fluid is also directed to the third hydraulic valve, which likewise remains closed because, according to the invention, it is closed when the first hydraulic line is pressurized.

[0007] Only when the gripper is fully open and thus in its open position does the switch activate the second hydraulic valve, which then becomes conductive and allows hydraulic fluid to flow from the first hydraulic valve into the third hydraulic cylinder of the tilting device. The third hydraulic cylinder is thus actuated, causing the tilting device to pivot the gripper and saw unit into its cutting position.

[0008] The grapple and saw unit can then be positioned on the crop. Both hydraulic lines are depressurized during this process. The third hydraulic valve remains in the closed position. Hydraulic fluid cannot flow from the third hydraulic cylinder through the first hydraulic valve either, as it is equipped with a check valve. The grapple and saw unit thus maintains its position, enabling precise positioning on the crop.

[0009] If the grapple is to be closed, the first hydraulic cylinder is actuated via the second hydraulic line, and the grapple closes. The third hydraulic valve then opens, allowing hydraulic fluid to flow from the third hydraulic cylinder, through the second and third hydraulic valves, into the first hydraulic line as soon as the crop has been cut and its own weight pivots the tipping mechanism, thereby returning the third hydraulic cylinder to its retracted position.

[0010] To protect the third hydraulic cylinder from overload, the first hydraulic valve is preferably designed to direct hydraulic fluid from the second hydraulic valve to the first hydraulic line when a first limit value of the output pressure is exceeded.

[0011] Furthermore, a fourth hydraulic valve is provided as a load-holding valve with overload protection for the first hydraulic cylinder. This valve is connected to the second hydraulic line on the inlet side and to the first hydraulic cylinder on the outlet side. The fourth hydraulic valve is designed to divert hydraulic fluid from the first hydraulic cylinder to the second hydraulic line when a second limit value for the outlet pressure is exceeded. The load-holding valve ensures that the pressure in the first hydraulic cylinder is maintained even when the second hydraulic line is depressurized. The fourth hydraulic valve thus prevents the gripper from opening unintentionally, but allows it to open in the event of an impending overload.

[0012] Furthermore, a fifth hydraulic valve can be provided, connected on the inlet side to the second hydraulic line and on the outlet side to a hydraulic motor and the second hydraulic cylinder for the cutting element. This fifth hydraulic valve is designed to direct hydraulic fluid from the second hydraulic line to the hydraulic motor and the second hydraulic cylinder when a third limit value for the inlet pressure is exceeded. The third limit value is selected such that the fifth hydraulic valve only opens when the gripper is completely closed. In this way, the cutting element is also only activated after the gripper is completely closed. After activation, the saw is swung out by the hydraulic motor using the second hydraulic cylinder.

[0013] Furthermore, it is proposed that a first reservoir for hydraulic motor leakage oil be provided, which is connected to the first hydraulic line. This first reservoir collects leakage oil from the hydraulic motor and returns it to the first hydraulic line after the sawing process is complete.

[0014] To prevent the hydraulic motor from running backwards when the first hydraulic line is pressurized, a sixth hydraulic valve is proposed, which is connected to the first hydraulic line on the inlet side and to the hydraulic motor on the outlet side, wherein the sixth hydraulic valve is designed to direct hydraulic fluid from the hydraulic motor into the first hydraulic line and to block it in the opposite direction.

[0015] Furthermore, a second accumulator for the hydraulic fluid of the second hydraulic cylinder is proposed for the return movement of the second hydraulic cylinder. With the help of this second accumulator, the cutting element is thus swung back into place after the cutting process is complete.

[0016] The invention will be explained in more detail below with reference to exemplary embodiments and the accompanying figures. These figures show the Fig. 1 a schematic view of a vehicle with a felling head according to the invention with a gripper and saw unit in the cutting position, Fig. 2 a schematic view of a vehicle with a felling head according to the invention with a gripper and saw unit in the storage position, Fig. 3a an enlarged view of the felling head in the cutting position, Fig. 3b an enlarged view of the felling head in the deposit position, Fig. 4a a top-down view of the gripper and saw unit, Fig. 4b a representation of the gripper and saw unit seen from below, so that the cutting element is visible, and the Fig. 5 a possible embodiment of a hydraulic circuit for a felling head according to the invention.

[0017] First, attention will be drawn to the Fig. 1 bis 4 Reference is made to explain the general functioning of a felling head according to the invention. Fig. 1 Figure 1 shows a schematic view of a vehicle 3 with a felling head 1 according to the invention, having a gripper and saw unit in the cutting position, and the Fig. 2 a schematic view of the vehicle 3 with a felling head 1 according to the invention with a gripper and saw unit in the deposit position.

[0018] The felling head 1 is attached to a boom arm of the vehicle 3, which is controlled by an operator from the vehicle 3 in such a way that gripper arms 4 arranged on the gripper and saw unit (see Fig. 3 ) the harvested crop 2, such as a tree trunk. Subsequently, a suitable hydraulic system is used to process the material contained within the Fig. 1 and 2 visible second hydraulic line 19b and a first hydraulic cylinder 5 (see Fig. 4a A closing pressure is exerted on the gripper arms 4, which fix the log via a pincer-like movement. After the log is fixed, the cutting element 6 (see Fig. 4b ) by means of a second hydraulic cylinder 8 so that the tree trunk is cut through. The cutting element 6 is designed as a chainsaw and is usually pivotably mounted in a saw housing, being driven by a hydraulic motor 7 arranged in the saw housing (see Fig. 4b ) is put into operation and can be swung out of the saw box using the second hydraulic cylinder 8 to cut through a log held by the grapple arms 4 in an area below the grapple arms 4. After the log has been cut, the grapple and saw unit can be tilted using a tilting device 9 (see Fig. 3 ) are pivoted so that the gripper arms 4 are moved from their cutting position according to Fig. 3a , in which the gripper arms 4 are essentially horizontally oriented and their gripper pivot axes are accordingly vertical, into a storage position according to Fig. 3b The gripper arms 4 are essentially oriented vertically, with their gripper pivot axes correspondingly horizontal. The severed tree trunk can then be placed down in a controlled manner by appropriately controlling the boom arm, whereby the gripper arms are positioned in the Fig. 1 and 2The visible first hydraulic line 19a and a corresponding return movement of the first hydraulic cylinder 5 open the gripper arms 4 to release the severed tree trunk. A third hydraulic cylinder 10 (see Fig. 3 ) and the tilting device 9 can move the gripper and saw unit from its storage position according to Fig. 3b back into their cutting position according to Fig. 3a be brought.

[0019] Subsequently, the following will be based on the Fig. 5 A possible embodiment of a hydraulic circuit for a felling head according to the invention is explained. If the grab is to be opened, the first hydraulic cylinder 5 is actuated by means of the first hydraulic line 19a, and the grab opens. By means of the first hydraulic valve 12, hydraulic fluid is directed from the first hydraulic line 19a to the second hydraulic valve 13, which initially remains closed because it is only opened by actuating a switch. In addition, hydraulic fluid is also directed to the third hydraulic valve 14, which also remains closed because it is closed when the first hydraulic line 19a is pressurized.

[0020] Only when the gripper is fully open and thus in its open position does it activate the second hydraulic valve 13 via a switch. This valve then becomes conductive and allows hydraulic fluid to flow from the first hydraulic valve 12 into the third hydraulic cylinder 10 of the tilting device 9. The third hydraulic cylinder 10 is thus actuated, causing the tilting device 9 to pivot the gripper and saw unit into its cutting position.

[0021] The grapple and saw unit can then be positioned on the crop. Both hydraulic lines 19a and 19b are depressurized. The third hydraulic valve 14 remains in the closed position. The hydraulic fluid cannot flow from the third hydraulic cylinder 10 through the first hydraulic valve 12 either, as it is equipped with a check valve. The grapple and saw unit thus maintains its position and enables precise positioning on the crop 2.

[0022] If the grapple is to be closed, the first hydraulic cylinder 5 is actuated by means of the second hydraulic line 19b, and the grapple closes. The third hydraulic valve 14 is then opened so that hydraulic fluid from the third hydraulic cylinder 10 can flow via the second hydraulic valve 13 and the third hydraulic valve 14 into the first hydraulic line 19a as soon as the crop 2 has been cut and its own weight pivots the tipping device 9, thereby returning the third hydraulic cylinder 10 to its retracted position. The opening of the third hydraulic valve 14 when the second hydraulic line 19b is pressurized is effected by means of a [missing information - likely a specific mechanism or feature]. Fig. 5Control line indicated by a dashed line, with which the pressure in the second hydraulic line 19b is taken from a fourth hydraulic valve 15 of the first hydraulic cylinder 5, designed as a load holding valve, to control the third hydraulic valve 14.

[0023] To protect the third hydraulic cylinder 10 from overload, the first hydraulic valve 12 is further designed to direct hydraulic fluid from the second hydraulic valve 13 to the first hydraulic line 19a when a first limit value of the output pressure is exceeded.

[0024] Furthermore, a fourth hydraulic valve 15, as already mentioned, is provided as a load-holding valve with overload protection for the first hydraulic cylinder 5. This valve is connected on the inlet side to the second hydraulic line 19b and on the outlet side to the first hydraulic cylinder 5. The fourth hydraulic valve 15 is designed to direct hydraulic fluid from the first hydraulic cylinder 5 to the second hydraulic line 19b when a second limit value of the outlet pressure is exceeded. The fourth hydraulic valve 15 thus prevents the gripper from opening unintentionally, but allows the gripper to open in the event of an impending overload.

[0025] Furthermore, a fifth hydraulic valve 11 is provided, which is connected on the inlet side to the second hydraulic line 19b and on the outlet side to the hydraulic motor 7 and the second hydraulic cylinder 8 for the cutting element 6. The fifth hydraulic valve 11 is designed to direct hydraulic fluid from the second hydraulic line 19b to the hydraulic motor 7 and the second hydraulic cylinder 8 when a third limit value of the inlet pressure is exceeded. The third limit value is selected such that the fifth hydraulic valve 11 only opens when the gripper is completely closed. In this way, the cutting element 6 is also only activated after the gripper is completely closed. After activation, the saw is swung out via the hydraulic motor 7 using the second hydraulic cylinder 8.

[0026] Furthermore, a first accumulator 17 is provided for leakage oil from the hydraulic motor 7, which is connected to the first hydraulic line 19a. This first accumulator 17 collects leakage oil from the hydraulic motor 7 and returns it to the first hydraulic line 19a after the sawing process has finished.

[0027] To prevent the hydraulic motor 7 from running incorrectly when the first hydraulic line 19a is pressurized, a sixth hydraulic valve 16 is provided, which is connected on the inlet side to the first hydraulic line 19a and on the outlet side to the hydraulic motor 7, wherein the sixth hydraulic valve 16 is designed to direct hydraulic fluid from the hydraulic motor 7 into the first hydraulic line 19a and to block it in the opposite direction.

[0028] Furthermore, a second accumulator 18 is provided for the hydraulic fluid of the second hydraulic cylinder 8 for the return movement of the second hydraulic cylinder 8. With the help of the second accumulator 18, the cutting element 6 is thus swung back into place after completion of the cutting process.

[0029] The invention provides a device for harvesting timber with a hydraulically controlled felling head 1, which enables the cutting position of the gripper and saw unit to be determined during positioning on the crop 2.

Claims

1. Device for timber harvesting having a hydraulically controlled felling head (1), which can be attached to the boom arm of a vehicle (3) and comprises a gripper and saw unit and a tilting device (9), wherein the gripper and saw unit has at least one pair of two gripper arms (4) for the harvested material (2), which can be actuated by a first hydraulic cylinder (5) and pivoted between an open and closed state, and a cutting element (6) for cutting through the harvested material (2), which can be pivoted out by a second hydraulic cylinder (8), and can be pivoted from a depositing position into a cutting position for the harvested material (2) by means of the tilting device (9) which can be actuated by a third hydraulic cylinder (10), wherein the first hydraulic cylinder (5) is connected to a first hydraulic line (19a) for opening the gripper arms (4) and to a second hydraulic line (19b) for closing the gripper arms (5), characterized in that a first hydraulic valve (12) provided with a non-return valve is provided, which is connected on the input side to the first hydraulic line (19a), and is connected on the output side to a second hydraulic valve (13), which is connected to the third hydraulic cylinder (10) designed as a single-acting hydraulic cylinder, and to a third hydraulic valve (14), via which the second hydraulic valve (13) is connected to the first hydraulic line (19a), wherein the third hydraulic valve (14) is designed to block when pressure is applied to the first hydraulic line (19a) and to open when pressure is applied to the second hydraulic line (19b), and the second hydraulic valve (13) is designed to conduct hydraulic fluid from the first hydraulic valve (12) to the third hydraulic cylinder (10) when a switch is actuated by the gripper arms (4) pivoted into their open state, and to conduct hydraulic fluid from the third hydraulic cylinder (10) to the third hydraulic valve (14) when the switch is not actuated when the gripper arms (4) are closed.

2. Device according to claim 1, characterized in that the first hydraulic valve (12) is designed to conduct hydraulic fluid from the second hydraulic valve (13) to the first hydraulic line (19a) when a first limit value of the output-side pressurization is exceeded.

3. Device according to claim 1 or 2, characterized in that a fourth hydraulic valve (15) is provided as a load-holding valve with an overload protection, which is connected on the input side to the second hydraulic line (19b) and on the output side to the first hydraulic cylinder (5), wherein the fourth hydraulic valve (15) is designed to conduct hydraulic fluid from the first hydraulic cylinder (5) to the second hydraulic line (19b) when a second limit value of the output-side pressurization is exceeded.

4. Device according to one of claims 1 to 3, characterized in that a fifth hydraulic valve (11) is provided, which is connected on the input side to the second hydraulic line (19b) and on the output side to a hydraulic motor (7) and the second hydraulic cylinder (8) for the cutting element (6), wherein the fifth hydraulic valve (11) is designed to conduct hydraulic fluid from the second hydraulic line (19b) to the hydraulic motor (7) and the second hydraulic cylinder (8) when a third limit value of the input-side pressurization is exceeded.

5. Device according to one of claims 1 to 4, characterized in that a first accumulator (17) for leakage oil of the hydraulic motor (7) is provided, which is connected to the first hydraulic line (19a).

6. Device according to one of claims 1 to 5, characterized in that a sixth hydraulic valve (16) is provided, which is connected on the input side to the first hydraulic line (19a) and on the output side to the hydraulic motor (7), wherein the sixth hydraulic valve (16) is designed to conduct hydraulic fluid from the hydraulic motor (7) into the first hydraulic line (19a) and to block it in the opposite direction.

7. Device according to one of claims 1 to 6, characterized in that a second accumulator (18) for hydraulic fluid of the second hydraulic cylinder (8) is provided for resetting movement of the second hydraulic cylinder (8).