HARVESTER HEAD IN A HARVESTING MACHINE
The present invention relates to a harvester head of a logging machine, comprising a frame - at least two supporting and/or feeding devices for supporting a trunk being treated and for moving it longitudinally, at least one mechanically operated supporting and feeding elements with a power transmission device connected to it one or more elements for gripping the trunk being treated, or a combined gripping, delimbing and/or barking device.
In modern mechanized log harvesting, chopping or harvesting heads mounted on various carrier machines are generally used. A harvester head grips the trunk of a tree to be felled by a point close to the ground surface, whereupon the tree is cut by a cutting device, usually a chain saw provided in the harvester head. However, a harvester head can also be used for treating trees already felled. A felled trunk is fed through the harvester head so that the various cutters or equivalent elements provided in the harvester head deiimb or bark the trunk and a cutting device cuts it into blocks of a suitable length. The harvester head is connected to a carrier machine, e.g. a forest tractor or an excavator, from which it receives its driving power via power transmission elements. The control of the functions of the harvester head and the recording of measurement data can be implemented in different ways, normally using a computer-based measuring and control system designed for the harvester head. Important elements of efficient and accurate harvester head operation are effective and cautious feed motion of the trunk being treated and a good ability to support the trunk, and normally a delimbing and/or barking capacity.
The harvester head is typically mounted on a hydraulically operated boom assembly of the carrier machine. The elements of the harvester head are generally hydraulically or electrically operated and connected to the hydraulic and electric systems of the carrier machine. The driver of the carrier machine generally controls and regulates the functions of the harvester head from the cabin of the carrier machine by using so- called control handles, which are connected to the above-mentioned measuring and control system or device, which again is connected to the electric and hydraulic system of the carrier machine.
In the harvester head, the trunk is fed, i.e. moved by means of various supporting and/or feeding elements supporting the trunk. These generally consist of rollers, wheels or cylinders mechanically driven by hydraulic motors, and also link chains of rubber or metal construction with a surface so shaped as to provide a good hold on the tree trunk, using e.g. various prongs, fins or chains. In this text, "mechanically driven roller or other element" refers to a device rotated by a motor or other drive means. "Freely rotating roller or other element" refers to a device that is not driven by a motor or other drive means but has been fitted to rotate freely without a drive means according to the movement of the trunk moving in contact with the element.
At least some of the above-mentioned supporting and/or feeding elements need to be capable of being moved relative to each other so that the trunk to be treated can be brought into the grip of the harvester head. Therefore, harvester heads normally have a grapple-like structure, and when a tree is to be gripped, the grapple is opened and set around the trunk. Once the trunk is appropriately inside the harvester head, the grapple is closed by actuating the normally hydraulically operated supporting, feeding or other gripping elements. Via such a grip of the supporting and/or feeding elements, controlled e.g. by hydraulic means, it is possible to influence the holding strength of the contact between said elements and the tree trunk. For instance, in the case of a slippery trunk or a trunk having a large diameter, a somewhat greater squeezing force can be applied than in the case of a smaller trunk or a trunk allowing a good hold, to ensure a secure grip. Once a grip on the trunk has thus been established, the trunk can be moved in its lengthways direction along a path defined by the harvester head, by using the trunk feeding devices now in contact with the tree trunk as supporting elements. In this way, the trunk can be moved through the harvester while various treatment devices, such as delimbing knives, provided in the harvester head are simultaneously performing the delimbing work. The feeding elements must generally allow operation in both directions so that the trunk can be moved both ways, because e.g. the delimbing or barking result is not always adequate after a first pass of treatment.
It is known that when a trunk is being fed through a harvester head, the feeding, supporting and gripping elements produce undesirable traces on the trunk. Moreover, typically only a portion of the power taken by the harvester head from its power engine can be utilized for trunk feed. Most of the power is lost because of the dissipation occurring in the hydraulic system, in the first place in the piping, and especially in
underpowered hydraulic motors. On the other hand, the frictional forces between the trunk and the gripping elements are fairly large, in the first place because of the latter support the trunk.
On the other hand, it is also known that the structures of the movable elements, such as the feeding, gripping and delimbing/barking devices of the harvester head, as well as the structural solutions used in the pivots and attachment points connecting these elements to the frame of the harvester head are complicated and often undersized in respect of strength. This is generally due to the fact that the forces generated in the harvesting process are distributed among too many pivots and attachment points.
Thirdly, the harvester head often works in conditions where it picks up trunks from the ground or from a pile. Prior-art devices have not been designed to work efficiently in these situations, among other things because of the inappropriate working principle of the gripping elements. Therefore, the productivity of prior-art devices is not sufficient in all situations.
The object of the invention is to achieve a device that will minimize the above- mentioned problems encountered in the state of the art. The above disadvantages are eliminated and the aims defined above are reached by applying the harvester head of the invention, which is characterized in that at least one pivot and/or attachment point in the path geometry of at least one supporting and/or feeding element is utilized as a pivot and attachment point in the path geometry of another supporting and/or feeding element or gripping element moving with a different path geometry.
A feature typical of the device and method of the invention is that the frame of the harvester head of the logging machine is provided with at least two elements for supporting and/or feeding the trunk to be treated, by means of which the trunk is moved longitudinally in the harvester head. 'Feeding' refers to moving the trunk being treated in the harvester head, and 'supporting and/or feeding elements' refers to the elements by means of which said longitudinal motion is accomplished. These supporting and feeding elements may consist of e.g. supporting and feeding rollers, wheels or cylinders. The substantially straight path that the trunk follows as it moves in the harvester head is called the path of trunk movement. The above-mentioned supporting and/or feeding elements, of which there are at least two, are fitted on the same side of the path of trunk movement. Usually supporting and/or feeding elements
are also provided on the other side of the feed path because elements placed on different sides help support the trunk evenly.
In some cases at least some of the supporting and/or feeding elements and also their paths are placed oppositely in substantially the same plane transverse to the path of trunk movement. It is naturally not necessary for all the elements and their paths to be located in the same above-mentioned plane, because the harvester head may comprise several such planes. However, the elements fitted on different sides of the path of trunk movement must provide uniform support of the trunk so that the trunk remains straight while being treated and moved. According to the invention, when the supporting and feeding elements or their paths are not placed oppositely in the same plane transverse to the path of trunk movement, the feeding elements may intercross when the feed device is being closed. This provides an improved capability of performing a trunk feed movement without causing damage, and the feeding elements have a substantially better ability to support the trunk than in existing solutions.
Providing two supporting and feeding elements on the same side of the path of trunk movement, each having a different path geometry as the trunk diameter changes, allows a trunk feed motion with less damage. At the same time, the efficiency of the power transmission elements, such as the hydraulic system, is improved as compared with current solutions. At least one of the above-mentioned supporting and/or feeding elements is mechanically operated while another one may be a freely rotating element. A mechanically operated element is needed for the transmission of motive power to move the trunk. The number of these mechanically operated elements is at least two, but the number of freely rotating elements may be larger. The harvester head of the invention naturally needs at least one power transmission device, such as a hydraulic or electric motor, to drive the said at least one mechanically operated trunk supporting and feeding element.
In addition, the harvester head of the invention comprises elements by means of which the said supporting and/or feeding elements or at least some of them can be moved relative to each other, in other words, their mutual distance and/or relative positions can be changed. This mechanism enables the harvester head to hold the trunk in a grapple-like grip and to apply a desired gripping pressure.
A particularly advantageous embodiment of the invention is characterized in that the gripping device or devices connected to the same pivots as the supporting and/or feeding elements can be moved separately from other trunk supporting and/or feeding elements if desired. This allows a substantially snagged or crooked or otherwise difficult trunk to be more easily fed through the device while improving its mechanical performance.
A preferred embodiment of the invention is characterized in that the means of adjusting the relative distance between the trunk supporting and/or feeding elements or the power transmission elements of the drive of the mechanically operated trunk supporting and feeding elements or both of said elements as well as the gripping elements are hydraulically operated.
A preferred embodiment of the invention provides the advantage that the trunk remains in a sufficiently straight position as at least one mechanically operated and at least one freely rotating or equivalent are fitted in substantially the same plane transverse to the path of movement of the trunk being treated.
In the following, the invention will be described in detail with reference to the attached drawings, wherein
Fig. 1 presents a harvester head according to the invention in a partially sectioned end view, depicted in the direction of the path of trunk movement. Fig. 2 presents the harvester head as seen from below.
Fig. 1 presents an example of the harvester head 1 of the invention in a working position in a situation where the harvester head has gripped a tree trunk 5. In Fig. 1 , the harvester head 1 is presented in a partially sectioned end view as seen in the direction of the path of movement of the trunk 5, so the trunk 5 is represented by its cross-section. Fig. 1 also shows the longitudinal axis 13 of the trunk 5, said axis forming the path of trunk movement in the harvester head.
In the example presented in Fig. 1 , the harvester head comprises a frame 2 with two pairs of supporting and/or feeding elements 3 and 4 mounted on it, which in the device presented are rollers 3a, 4a and 4b. The counterpart 3b of roller 3a is not shown in Fig. 1. In addition, mounted on the frame 2 are two pairs of gripping elements 9 and
10. The gripping elements 9a, 9b and 10a presented in Fig. 1 may also serve as supporting elements, delimbing elements and/or barking elements, consisting of e.g. knives. The counterpart 10b of gripping element 10a is not shown in Fig. 1. The operation of the elements of this example device will be described below in detail.
Although the supporting and/or feeding elements 3 and 4 as well as the gripping and delimbing means 9 and 10 in the example of a harvester head 1 presented in Fig. 1 are arranged in a pairwise fashion, they can alternatively be arranged individually. In this case, for each individual support or feeding element, a corresponding supporting arrangement implemented in some other way, e.g. using one or more freely rotating rollers, cylinders or equivalent elements, is provided on the opposite side of the trunk 5. Generally, the forces applied to the trunk 5 from a lateral direction should be balanced so that, if there is no balancing supporting element on the opposite side of the trunk in direct alignment with a supporting and feeding element, then a support is provided using at least two supporting elements placed at a distance from each other.
As the supporting, feeding and gripping elements are located at different levels along the trunk 5, i.e. in separate planes transverse to the longitudinal direction of the trunk 5, at least three supporting elements, such as e.g. rollers, chains or gripping elements, are needed to ensure a balance and a straight motion of the trunk. In this case, one element is placed on one side of the trunk while the other two elements are placed on the opposite side.
The first rollers 3a and 3b presented in the harvester head 1 in Fig. 1 are trunk supporting and feeding rollers positively driven by hydraulic means. The rollers 4a and 4b of the second roller pair are trunk supporting and feeding rollers implemented with a different motion geometry, which in this example are also positively driven by hydraulic means. However, all rollers 3 and 4 need not necessarily be positively driven, for some of the rollers may be freely rotating supporting rollers.
The gripping elements 9a, 9b, 10a and 10b are mounted on the frame 2 via the same pivots and attachment points 11a, 11 b, 12a and 12b as the supporting and feeding rollers 3a, 3b, 4a and 4b. Rollers 3a, 3b, 4a and 4b and their paths are located in separate planes transverse to the path 13 of movement of the trunk 5 but close to each other on different sides of the trunk 5 being treated so that the trunk 5 being treated is supported from several directions. Further elements corresponding to 3a,
3b, 4a, 4b, 9a, 9b, 10a and 10b may be provided, and they may be fitted in the same or a different plane than the elements shown in Fig. 1.
In the harvester head 1 in Fig. 1 , both gripping element 9a and roller 4a are mounted on an outer shaft 31 on the left-hand side in Fig. 1 so that they can be turned about pivot 11a. By means of a pushing device 7a, e.g. a hydraulic cylinder, the gripping element 9a and the roller 4a are turned towards the trunk 5. Gripping element 9b and roller 4b on the opposite side of the trunk 5 are similarly mounted on a second shaft 32 so that they can be turned about pivot 11b. By means of a pushing device 7b, the gripping element 9a and the roller 4a can be turned towards the trunk 5.
The pushing devices 7a and 7b may be interconnected e.g. so that pushing device 7a is connected to a hydraulic cylinder while the other pushing device 7b is connected to the piston of the same cylinder. Alternatively, it is also possible to use two hydraulic cylinders connected to the same hydraulic circuit. With this arrangement, the gripping elements 9a and 9b as well as the rollers 4a and 4b on different sides of the trunk 5 can be turned simultaneously around the trunk 5.
When the arm 9 of the gripping element is moved, the other mechanically operated supporting and feeding roller 4 connected to it moves also. Thus, in this example, the supporting and feeding roller 4 and the gripping element 9 always move simultaneously about the same pivot and attachment point 11. Still, the forces of the gripping element 9 as a delimbing and/or barking device can be transmitted separately further away from the trunk 5 while the supporting and feeding roller 4 remains in contact with the trunk surface.
Although the gripping element 9a and the roller 4a move together, they are not necessarily locked to each other. In such a solution, these elements are interconnected by a regulating element, such as e.g. a hydraulic cylinder, spring or equivalent, by means of which the relative position and distance between the gripping element 9a and the roller 4a can be adjusted. In this way it is possible, among other things, to define the distance from the trunk 5 to which the gripping element 9a or e.g. a delimbing knife mounted in place of it is admitted while the trunk 5 is being moved in the harvester head 1. The relative position and distance between the gripping element 9b and the roller 4b on the opposite side of the trunk 5 can be adjusted in a corresponding manner. In Fig. 1 , the range of adjustment motion of roller 4b is
depicted with broken lines. If the roller 4b is adjusted to a closer distance from the trunk 5, then the knife 9b will move further away from the surface of the trunk 5. Correspondingly, by adjusting the roller 4b to a larger distance from the surface of the trunk 5, the knife 9b can be brought closer, for instance in a gripping situation.
The harvester head 1 in Fig. 1 also comprises a second pair of regulating elements, comprising a gripping element 10a and a roller 3a on the left-hand side of the trunk 5 in Fig. 1 , and similarly on the right-hand side of the trunk 5 a gripping element 10b and a roller 3b, though these are only shown in Fig. 2. Gripping element 10a is connected to the inner shaft 33 shown on the left in Fig. 1 so that it turns about pivot 12a, whereas roller 3a is connected via an articulated linkage system formed by adapters 35 and 36 to both shafts 31 and 33 so that the path of motion of the roller 3a directed towards the trunk 5 is only slightly curved. A turning movement of gripping element 10a is produced by a pushing device 8, which may also consist of e.g. a hydraulic cylinder whose piston in connected to a corresponding gripping element 10b placed on the opposite side of the trunk 5. In this connection, too, it is possible to use two hydraulic cylinders connected to the same hydraulic circuit. Thus, both gripping elements 10a and 10b are made to work together.
Gripping element 10a and roller 3a and similarly gripping element 10b and roller 3b move simultaneously, but they are not locked to each other as they differ in respect of their geometry of motion. They only have shaft 33 in common. However, between gripping element 10a and roller 3a and similarly between gripping element 10b and roller 3b there may be a regulating element, such as e.g. a hydraulic cylinder, spring or equivalent, by means of which the relative position and distance between the gripping element and the roller on the same side can be adjusted. To allow synchronization of the movements of the actuator pairs placed on opposite sides, a stabilizer bar 8 is connected by one end to the middlemost adapter 36 of the articulated linkage system of roller 3a and by the other end to the corresponding actuator on the other side. If necessary, the devices 7 and 8 controlling the play of, i.e. the distance between the roller 4 and the gripping element 9 can be fitted to move all the supporting and feeding elements as well as all the gripping elements.
The other corresponding pair on the other side of the path 13 of trunk 5 movement presented in the example in Fig. 1 has been fitted to be moved in a corresponding manner. To implement its movements, hydraulic devices, stabilizer bars or equivalent
are needed, which are not shown in full in Fig. 1. Fig. 1 also shows a hydraulic motor 6 used to drive the supporting and/or feeding elements 3 and 4, in this case mechanically operated rollers. The number of said supporting and/or feeding elements 3 and 4 or the number of devices used to move and/or drive them may naturally be larger than the numbers stated above. In addition, the harvester head 1 is generally provided with other elements, such as various cutters, saws, sensors, measuring rollers, supporting rollers or trunk marking devices as well as equipment needed for the felling of a tree, which are not shown in Fig. 1.
The harvester head 1 is mounted on a suitable carrier machine, e.g. an excavator, using various connectors and/or fixing elements known in themselves. Moreover, the hydraulic devices of the harvester head 1 are hydraulically connected to the hydraulic system of the carrier machine in a manner known in itself. The carrier machine or the connectors, fixing elements and hydraulic elements connecting it to the harvester head are not shown in this figure. Neither does the figure show the data transfer elements preferably fitted in the harvester head 1 , such as electric conductors, which are used to transmit the measurement signal obtained from a pulse sensor or equivalent provided in the harvester head to a measuring and control device in the carrier machine.
The preferred harvester head according to the invention presented in Fig. 1 works as follows. The harvester head 1 is opened by driving elements 3,4,9 and 10 so that their fixing arms turn about the pivots and attachment points 11 and 12, simultaneously turning the supporting and/or feeding elements 3 and 4 and the gripping elements 9 and 10 farther apart, i.e. in a direction away from the path 13 of movement of the trunk 5 to be treated. The opened harvester head 1 is then placed around the trunk 5 of a standing or already felled tree, at a desired point along the trunk. The harvester head 1 is closed by driving said elements 3, 4, 9 and 10 in the opposite direction, in other words, these elements 3, 4, 9 and 10 are pressed against the tree trunk 5.
The trunk of a tree 5 not yet felled is cut by means of a crosscut saw provided in the harvester head but not shown in Fig. 1. After the trunk 5 has been cut, the harvester head 1 and at the same time the tree 5 being treated and held in its grip is released or turned into a working position, i.e. generally so that the trunk of the tree 5 being treated lies mainly parallel to the ground surface, in practice generally in a horizontal position. By means of the hydraulic devices 7 and 8, the pressing force applied to the
tree trunk by the supporting and feeding elements 3 and 4 and the gripping elements 9 and 10 is adjusted to a desired magnitude. In this way, the grip of the supporting and feeding elements 3 and 4 and the gripping elements 9 and 10 on the tree trunk 5 can be adjusted so as to provide an appropriate hold in each situation.
The tree trunk 12 being treated is moved longitudinally, i.e. along the path of trunk movement, by operating the hydraulic motors 6, which have been fitted to drive the trunk feed rollers 3 and 4. The surfaces of the rollers 3 and 4 have been so shaped that they can hold the trunk 5 in a secure grip, and when the rollers 3 and 4 are rotating, the trunk 5 will move. A measuring roller fitted to rotate freely and a support point fixedly fitted on the frame 2 keep the tree trunk 5 straight while the feed rollers 3 and 4 are pressing the trunk 5 from different sides of it. The treatment of the trunk can not always be finished with a single pass of the trunk through the harvester head, in which case the trunk 5 has to be moved several times back and forth through the harvester head 1. Therefore, the hydraulic motors 6 driving the rollers 3 and 4 must be capable of two-way operation.
After the desired treatment of the trunk 5 has been completed, the harvester head 1 is opened by operating devices 7 and 8 so as to turn the arms 3 and 4 and thereby the supporting and feeding elements 3 and 4 further apart, i.e. in a direction away from the path 13 of movement of the trunk 5 being treated. Likewise, the gripping elements 9 and 10 are moved in a direction away from the path of trunk 5 movement. After that, the remaining part of the tree trunk 5 thus treated is dropped from the harvester head 1 to a desired place, whereupon the harvester head 1 is ready for the next tree trunk 5. In some cases, it is also possible to treat a number of smaller trunks in the harvester head simultaneously.
Fig. 2 presents the harvester head 1 as seen from below. As shown in the figure, the frame 2 comprises four shafts 31 , 32, 33 and 34, on which both the gripping elements 9a, 9b, 10a, 10b and the supporting and feeding rollers 3a, 3b, 4a, 4b are mounted. In Fig. 2, only the articulated link mechanism of the left-hand roller 3a is connected to both shafts 31 and 33 on the left side, whereas gripping element 9a and roller 4a are only connected to the outer shaft 31 and gripping element 10a only to the inner shaft 33. Similarly, the articulated link mechanism of the right-hand roller 3b is connected to both shafts 32 and 34 on the right-hand side. Gripping element 9b and roller 4b are only connected to the outer shaft 32 and gripping element 10b only to the inner shaft
34. When the harvester head grips a tree trunk 5, both the gripping elements 9a, 9b, 10a, 10b and the rollers 3a, 3b, 4a, 4b are pressed about the trunk 5. At least some of the rollers 3a, 3b, 4a and 4b are connected to a drive means for moving the trunk 5 in the direction of its longitudinal axis 13 along the path of trunk movement, so that the trunk 5 is delimbed and/or barked by knives optionally attached to the gripping elements 9a, 9b, 10a and 10b.
Fig. 2 gives a clear picture of the simplicity and serviceability of the disclosed harvester head 1. To allow a slightly curved or linear squeezing motion of supporting and feeding rollers 3a and 3b, the harvester head needs to be provided with articulated link mechanisms, which in Fig. 1 are indicated by reference numbers 35 and 36, and on either side of the trunk 5 with two shafts, which are shafts 31 and 33 on the left-hand side and shafts 32 and 34 on the right-hand side in both figures. According to the invention, these shafts are utilized by placing all the other elements squeezing the tree trunk 5 on these same shafts.
Thus, the outer shafts 31 and 32 in the frame 2 of the harvester head 1 carry supporting and feeding rollers 4a and 4b and gripping elements 9a and 9b. The motion geometries of all these elements 4a, 4b, 9a and 9b are circular motions and in principle identical to each other, yet clearly different from the linear motion geometries of supporting and feeding rollers 3a and 3b supported by two shafts. The inner shafts 33 and 34 in the frame 2 of the harvester head 1 support only gripping elements 10a and 10b, whose motion geometries are also circular motions. However, these motion geometries differ clearly both from the motion geometries of the above-mentioned elements mounted on the outer shafts and from the linear motion geometries of the supporting and feeding rollers 3a and 3b supported by two shafts.
In the manner described above, a structurally simple solution is thus achieved, wherein, by utilizing the same shafts in the frame 2 of the harvester head 1 , supporting and feeding or gripping elements working with several different motion geometries are achieved. By using elements working simultaneously with different motion geometries, very effective treatment of a tree trunk 5 can be accomplished.
It is obvious to the person skilled in the art that the invention is not restricted to the example described above, but that the invention may be varied within the scope of the claims presented below. The device of the invention need not necessarily comprise
rollers, or there may be other suitable devices fitted in the harvester head. The elements, motors and power transmission of the harvester head may be powered by other means than hydraulic, such as e.g. electric or combustion engine based means of operation. The control and measuring device may consist of several parts, one or some of which may be placed in the harvester head. The supporting and feeding rollers may be made of any suitable material or combination of materials, such as metal, plastic or rubber.