US-12622369-B2 - Device for harvesting timber

US12622369B2US 12622369 B2US12622369 B2US 12622369B2US-12622369-B2

Abstract

Device for timber harvesting having a felling head which includes a gripper and saw unit and a tilting device. The gripper and saw unit have gripper arms which can be actuated by a first hydraulic cylinder and a cutting element which can be pivoted out by a second hydraulic cylinder, and can be pivoted from a depositing position into a cutting position for the harvested material with the aid of the tilting device, which can be actuated by a third hydraulic cylinder. 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. The tilting device can be pivoted from its cutting position into its depositing position by pressurizing the second hydraulic line in a pressure range in which the cutting element remains in an inactive state.

Inventors

Werner Steininger

Assignees

Werner Steininger

Dates

Publication Date: 20260512
Application Date: 20220524
Priority Date: 20210602

Claims (8)

1 . A device for timber harvesting having a hydraulically controlled felling head, which can be attached to the boom arm of a vehicle and comprises a gripper and saw unit and a tilting device, wherein the gripper and saw unit has at least one pair of two gripper arms for harvested material, which can be actuated by a first hydraulic cylinder and pivoted between an open and closed state, and a hydraulically activatable cutting element for cutting through the harvested material, and can be pivoted from a depositing position into a cutting position for the harvested material by the hydraulically actuatable tilting device, wherein the gripper arms of the gripper and saw unit can be pivoted into the open state and the tilting device can be pivoted into its cutting position by pressurizing a first hydraulic line, and the gripper arms can be pivoted into the closed state and the cutting element is activated for cutting through the harvested material by pressurizing a second hydraulic line, wherein the tilting device can be pivoted from its cutting position into its depositing position by pressurizing the second hydraulic line in a pressure range in which the cutting element remains in an inactive state.
2 . The device according to claim 1 , wherein a first hydraulic cylinder designed as a double-acting hydraulic cylinder is provided for hydraulic actuation of the at least one pair of grippers, which is connected to the first hydraulic line for opening the at least one pair of grippers and is connected to the second hydraulic line for closing the at least one pair of grippers, and a second hydraulic cylinder is provided for hydraulic activation of the cutting element, which is connected to the second hydraulic line, and a third hydraulic cylinder, which is connected to the first hydraulic line, is provided for hydraulic actuation of the tilting device, wherein a first hydraulic valve provided with a non-return valve is provided, which is connected on the input side to the first hydraulic line and is connected on the output 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 block when pressure is applied to the first hydraulic line and to open in a pressure range when pressure is applied to the second hydraulic line, in which the cutting element remains in an inactive state, and the second hydraulic valve is designed to conduct 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 state, and to conduct hydraulic fluid from the third hydraulic cylinder to the third hydraulic valve when the switch is not actuated when the gripper arms are closed.
3 . The device according to claim 2 , wherein the first hydraulic valve is designed to conduct hydraulic fluid from the second hydraulic valve to the first hydraulic line when a first limit value of the output-side pressurization is exceeded.
4 . The device according to claim 2 , wherein a fourth hydraulic valve is provided as a load-holding valve with an overload protection, which is connected on the input side to the second hydraulic line and on the output side to the first hydraulic cylinder, wherein the fourth hydraulic valve is designed to conduct hydraulic fluid from the first hydraulic cylinder to the second hydraulic line when a second limit value of the output-side pressurization is exceeded.
5 . The device according to claim 2 , wherein a fifth hydraulic valve is provided, which is connected on the input side to the second hydraulic line and on the output side to a hydraulic motor and the second hydraulic cylinder for the cutting element, wherein the fifth hydraulic valve is designed to conduct hydraulic fluid from the second hydraulic line to the hydraulic motor and the second hydraulic cylinder when a third limit value of the pressure applied on the input side is exceeded.
6 . The device according to claim 2 , wherein a first accumulator for leakage oil from the hydraulic motor is provided, which is connected to the first hydraulic line.
7 . The device according to claim 2 , wherein a sixth hydraulic valve is provided, which is connected on the input side to the first hydraulic line and on the output side to the hydraulic motor, wherein the sixth hydraulic valve is designed to conduct hydraulic fluid from the hydraulic motor into the first hydraulic line and to block it in the opposite direction.
8 . The device according to claim 2 , wherein a second accumulator for hydraulic fluid of the second hydraulic cylinder is provided for resetting movement of the second hydraulic cylinder.

Description

The invention relates to a device for timber harvesting having a hydraulically controlled felling head, which can be attached to the boom arm of a vehicle and comprises a gripper and saw unit and a tilting device, wherein the gripper and saw unit has at least one pair of two gripper arms for harvested material, which can be actuated by a first hydraulic cylinder and pivoted between an open and closed state, and a hydraulically activatable cutting element for cutting through the harvested material, and can be pivoted from a depositing position into a cutting position for the harvested material by means of the hydraulically actuatable tilting device, wherein the gripper arms of the gripper and saw unit can be pivoted into the open state and the tilting device can be pivoted into its cutting position by pressurizing a first hydraulic line, and the gripper arms can be pivoted into the closed state and the cutting element is activated for cutting through harvested material by pressurizing a second hydraulic line, according to the preamble of claim 1. Devices of this type are used for timber harvesting, wherein an operator controls a boom arm from the vehicle in such a way that gripper arms arranged on a gripper and saw unit embrace the harvested material, such as a tree trunk, wherein a closing pressure is subsequently exerted on the gripper arms via a corresponding hydraulic system via the second hydraulic line mentioned at the beginning and a first hydraulic cylinder, which fix the tree trunk relative to the boom arm via a pincer-like movement. Once the tree trunk has been fixed, the cutting element can be pivoted using a second hydraulic cylinder so that the tree trunk is cut through. The cutting element is designed as a chainsaw and is usually pivotably mounted in a saw box, wherein it can be put into operation using a hydraulic motor arranged in the saw box and swung out of the saw box using a hydraulically operated pivot drive in order to cut through a tree trunk held by the gripper arms in an area below the gripper arms. After cutting through the tree trunk, the gripper and saw unit can be pivoted using the tilting device so that the gripper arms are moved from their cutting position, in which the gripper arms are essentially horizontally oriented and their gripper pivot axes are correspondingly vertical, to a depositing position, in which the gripper arms are essentially vertically oriented and their gripper pivot axes are correspondingly horizontal. The severed tree trunk can then be deposited by activating the boom arm accordingly, wherein the gripper arms are opened via the first hydraulic line mentioned above and a corresponding resetting movement of the first hydraulic cylinder in order to release the severed tree trunk. With the aid of the third hydraulic cylinder and the tilting device, the gripper and saw unit can be moved from its depositing position back to its cutting position. The hydraulically actuated processes of gripping and cutting as well as opening the gripper and pivoting the tilting device are usually implemented with the aid of pressure sequencing controls. A hydraulic sequencing valve is used to close the gripper and, once the gripper is fully closed, to start up and pivot out the cutting element via the same hydraulic line. With the aid of a further hydraulic sequencing valve, both the opening of the gripper and, after the gripper has been fully opened, the actuation of the tilting device for pivoting the gripper and saw unit into their cutting position are accomplished via a further hydraulic line in the depositing position. A hydraulic valve is used to switch between the two hydraulic lines, but at least one hydraulic line must have a connection to the hydraulic fluid tank when not connected in order to enable the cutting element to retract after the cut has been completed. This connection to the hydraulic fluid tank means that after the gripper is fully opened and the tilting device is actuated, it is no longer held in the cutting position after switching to the unconnected state, for example to position the felling head on the harvested material and activate the cutting element, but can sink down again due to gravity. This proves to be disadvantageous in operation, particularly after the tree has been cut through, because the tilting device is pivoted into its depositing position by the weight of the cut tree, and therefore essentially uncontrolled. It is therefore the object of the invention to realize a device for timber harvesting with a hydraulically controlled felling head which avoids this disadvantage and enables the tilting device to be pivoted from the cutting position to the depositing position in a controlled manner. These objects are realized by the features of claim 1. Claim 1 relates to a device for timber harvesting having a hydraulically controlled felling head, which can be attached to the boom arm of a vehicle and comprises a gripper and saw unit and a tiltin