WO1992005757A1

WO1992005757A1 - Feeding device at the end of a pivotable boom in a tree manipulating machine, especially grapple harvester

Info

Publication number: WO1992005757A1
Application number: PCT/FI1991/000310
Authority: WO
Inventors: Arto Timperi; Marko Paakkunainen
Original assignee: Plustech Oy
Priority date: 1990-10-08
Filing date: 1991-10-08
Publication date: 1992-04-16
Also published as: FI90613C; FI904931A; FI904931A0; FI90613B; AU8627991A

Abstract

Tree feeding device at the end of a pivotable boom in a tree manipulating machine, especially grapple harvester, comprises rotating feeding means driven by a feed motor (M) provided for rotation by the effect of pressure medium, a line of pressure medium (LM) being passed through said motor and being connected through two separate lines (L2, L5) to a source (P) of pressure medium and through two separate lines (L3, L6) to a return line (T) of pressure medium. The above-mentioned lines comprise control means for controlling the flow of pressure medium, placed in the part carrying the feeding means at the boom end and being flow control valves (2, 6, 5, 3) adjustable in a stepless manner. The valves are connected to a pilot valve (1, 4) provided for controlling the pilot flow of pressure medium in the flow control valve for bringing about a change in the pressure medium line passing through said flow control valve.

Description

Feeding device at the end of a pivotable boom in a tree manipulating machine, especially grapple harvester

The invention relates to a tree feeding device at the end of a pivotable boom in a tree manipulating machine, said device being disclosed in the preamble portion of Claim l.

In tree manipulating machines, such as grapple har- vesters, there are feeding means feeding a tree forward which clamp the tree therebetween and bring about the feeding of the tree as they rotate. These kinds of feeding means are commonly driven by a hydraulic motor. A pressure medium, such as hydraulic oil, is supplied through flexible hoses from the pump of a work machine up to the part carrying said feeding line at the boom end. Within the same part comprising the feeding means, there are also other working means requiring hydraulic fluid, such as cylinders that press the feeding means against the tree, a saw performing the cutting of the tree, etc.

The present devices of the type described above have the drawback that their pressure losses become quite large. Particularly the feeding motors consume a lot of power, and consequently particular economical demands are made on the structure of their control means. As a whole, the operating systems of the above- mentioned parts at the end of work machines are quite complicated in structure comprising a lot of hoses, they are difficult to maintain, they are prone to defects and require a lot of space physically and are heavy.

The aim of the invention is to eliminate the above- mentioned drawbacks and provide a tree feedin^g device by means of which space can be saved and whi ..,. has a simpler structure and involves smaller pressure losses. For "accomplishing this purpose, the tree feeding device according to the invention is mainly charac¬ terized by what is disclosed in the characterizing portion of Claim 1. The control means of pressure medium are flow control valves that regulate the flow of pressure medium passing through the feed motor and are adjustable in a stepless manner and controllable by means of a pilot valve. The flow control valve adjustable in a stepless manner is characterized by a rapid response and a small pressure loss, thus decreas¬ ing the power demand of the feeding device. The flow control valves are situated in the part situated at the end of the pivotable boom in a tree manipulating machine and they can be controlled electronically through pilot valves that can be controlled electroni¬ cally from the cabin. In this way, a rapid operation of the corresponding actuators is achieved because the control means are close to the actuators and not e.g. on the other end of a flexible hydraulic hose that is several metres long and slows down the opera¬ tion.

According to one advantageous embodiment, the flow control valves are connected pairwise to a common pilot valve in such a manner that the pilot lines controlling the valves of a given pair pass through the same pilot valve. The lines between the pressure medium and the motor, and between the motor and the return line, respectively, comprise each in this case the flow control valves for different pairs. It is hence possible to control, to open or to close, the valves of the pair of valves that cause the rotation of the motors and consequently the rotating of the feeding means in a given direction by using a single pilot valve. The number of the pilot valves needed is thus smaller than that of the flow control valves. The number of the pilot valves can be e.g. two, in which case they can be 4/2-valves. According to one advantageous embodiment, the pilot valves are proportional valves, in which case the tree feeding speed can be regulated in a stepless manner.

Further according to one advantageous embodiment, the flow control valves are realized using cartridge technique, in which case they are fixed on a valve block including the corresponding lines of pressure medium.

Still according to one advantageous embodiment, the flow control valves constitute the last block of the rest of a control means assembly, also accomplished by means of block technique, as seen in the flow direction of the pressure medium.

The invention will be described in the following more closely with reference to the accompanying drawings wherein

Fig. 1 shows a tree feeding device in a schemat- ical view,

Fig. 2 shows the position of the tree feeding device according to the invention in a larger entity,

Fig. 3 shows the assembly of the system of Fig. 2, and

Fig. 4 shows the part of a tree manipulating machine where the tree feeding device according to the invention is situated.

Figure 1 shows the tree feeding device according to the invention by means of a hydraulic scheme. The device comprises hydraulic motors M driving the tree feeding means. The motors are connected in parallel to a source P of pressure medium. A pressure medium line LM passes through the motors, and the motors are double-acting, i.e. they can rotate in both directions. At one side, the motors are connected to a return line T of pressure medium through a line L3 and to a main line L from the pump P through a line L2. At the opposite side, the motors are in a corresponding manner connected to the return line T through a line L6 and to the line L through a line L5. The flow passing in the line L3 is controlled by a flow control valve 3 and the flow passing in the line L2 is controlled by a flow control valve 2. The lines L3 and L2 are passed through the valves in such a manner that the motors are connected in parallel to the line L3, and the line L2 branches off from the line L3 at the valve 3 e.g. through a bore in the valve body. The line L6 passing through the valve 6 and the line L5 passing through the valve 5 are situated on the opposite side of the motors M in a corresponding manner.

The figure shows two motors connected in parallel. The number of motors can be also higher than two, corresponding to the number of the feed means. In some applications, only one tree feeding means is driven and then only one motor is needed. The motors can be connected also in series.

The principle of the device is that when the valves 3 and 5 are open, the lines L5 and L3 are open and the pressure medium can flow from the pump P through the motor M to the return line T. The valves 2 and 6 are in this event closed. Correspondingly, when the valves 2 and 6 are open, the pressure medium can flow from the pump P through the line L2 and through the motor M to the line L6, and the valves 3 and 5 are in this event closed. The valves 2 and 6 as well as 3 and 5 form thus valve pairs, where the valves are always simultaneously open and effect the rotation of the motor M and consequently that of the feeding means to one direction. When the valves of the other valve pair are open, the motors rotate in the opposite direction. The valves 2, 3, 5, and 6 are flow control valves which are adjustable in a stepless manner. The flow control valves are in the case of Fig. 1 so-called valvistors, where the adjustment of the poppet that adjusts the throtting region and is movable in relation to the body of the valvistor takes place by adjusting the flow rate in a pilot line a„, a^ that exits from the valvistor and branches off from the line L2, L3, L5, or L6 passing through the valvistor. The pilot line joins the line after the corresponding valve. The flow rate in the pilot line determines thus the amount of flow passing through the valve. The flow passing in the pilot lines is adjusted by means of pilot valves 1 and 4 which are so arranged that the pilot lines from a given valve pair, the line a_p for the valve (2 or 5) located in the line passing from the pump, and the line a^ for the valve (3 or 6) located in the line passing to the return line, are passed through their respective pilot valve l or 4. A separate pilot valve is thus not needed for each flow control valve, and the number of valves needed is less than four. As shown by Fig. 1, the pair of valves 2, 6 is controlled by means of the pilot valve 1 and the pair of valves 3, 5 by means of the pilot valve 4. The pilot valves 1, 4 are 4/2-valves, which in their first posxcions close the pilot lines and at the same time the lines passing through the valves of the corresponding valve pair, and in their second positions open these lines. According to the control principle described above, one of the pilot valves is always closed when the other valve is open. The pilot valves 1 and 4 are proportional valves controllable electrically from the cabin. Hence, only two solenoids denoted by reference numerals la and 4a are needed for adjusting the speed and direction of the tree feeding means. By using only two pilot valves it is possible to create a smaller and lighter valve assembly in the part at the boom end, compared with a traditional one. In some applications the pilot valves 1 and 4 can be also on/off-valves, in which case the speed of the feeding means is constant. Also in this case it is advantageous to use flow control valves that can be adjusted in a stepless manner, because these kind of valves are sensitive, i.e. they have a rapid response.

The control entity formed by the pilot valves 1 and 4 has three positions in practice:

- Both valves closed and the feeding means stopped.

The first valve open and the second one closed and the feeding means rotating in the first direction and able to feed a tree in the first direction.

- The second valve open and the feeding means rotating to the second direction and able to feed a tree to the second direction.

The control of the valves 1 and 4 can be provided by means of control automatics in such a manner that when either of the valves is opened, the other one is simultaneously closed if it has been previously open. The valves can be spring-loaded in such a way that they close the pilot line in the rest position by the effect of the spring.

The flow control valves 2, 3, 5, and 6 are most preferably cartridge valves, so-called valvistor cartridges, fixed on the valve block containing the lines L2, L3, L5, and L6. A small pressure loss and on the other hand a relatively compact entity can be reached by means of this block-type structure. The arrangement of Fig. 1 allows to position the ports in the best possible way and to effect a valve assembly which can be well maintained and whose manufacture is economical.

Figure 2 shows the position of the valve assembly of Fig. 1 in a larger entity. The valves 2, 3, 5, and 6 controlling the flow to the motors M are situated at the end of the main line L entering the part situated at the boom end, and they constitute the last means to require power. The corresponding valve block 9 is denoted by dash-and-dot lines 2 in Fig. 2. The ports to the first motor are denoted by reference numerals Al and Bl and to the second motor by reference numerals A2 and B2.

The means controlling other actuators of the part are also accomplished by means of block technique, these blocks being denoted by reference numerals 8. The main line L, the return line and the lines passing from them to various actuators through various valves are constituted of rigid bores in the compact entity formed by the blocks. The main line L and the return line T are passed through the base block 10, on which is fixed an inlet block 7, other blocks 8 controlling the actuators, and the last block 9 containing the above-mentioned valves 2, 3, 5, and 6. Line pairs branch off from the block 10 to the blocks 8 preced¬ ing the block 9 in the flow direction of the line L. The block 9 is preceded by a block that contains the control means for the clamp means carrying the feeding means. This block has been described in more detail in the previous patent application No. 904213 by the Applicant. The main line L enters the part and the return line T leaves the part through the inlet block 7 that is fixed on the block 10. The inlet block 7 contains means for controlling the action of the cutting saw and the means comprise a flow control valve 7a accomplished by means of cartridge technique and controllable in a stepless manner. The flow control valve controls the flow of pressure medium in a line that branches off from the main line in the block 7 towards the motor that rotates the saw. A relief valve 7b limiting the maximum pressure of the whole entity of blocks is also fixed on the inlet block 7.

Figure 3 shows a possibility to build the entity shown schematically by Fig. 2, using the block techni- que. The corresponding blocks and control valves are denoted in the figure by the same reference numerals as above. Using the block technique, it is possible to make the construction of the tree manipulating machine very simple, compact and easily maintainable as far as its control system is concerned. Only two hydraulic hoses are needed for the supply of the pressure medium, one for the main line L from the pump and the other for the return line T to the tank. The corresponding ports in the inlet block 7 are denoted by arrows L and T. The block 9 controlling the feed motors is fixed on the opposite end of the base block 10.

The ports to the actuators can be arranged so that the ports to the saw motor are in the inlet block 7, the ports to the actuators controlled by the blocks 8 are in the base block 10, and the ports to the feed motors are in the block 9.

The "modularity" and good packing density is an impor¬ tant feature for the total operation of the system. The actuator ports that form pairs can be provided in the manner shown by Fig. 3 on the opposite sides of the piece constituted of the blocks, i.e. on the vertical sides of the inlet block 7, base block 10 and feed motor block 9. The control means are fixed on the upper sides that connect the said vertical sides.

Figure 4 shows further the part at the boom end of the tree manipulating machine. The invention is of particular use in this part. The example in question is a grapple harvester, in which the blocks of the control system can be mounted as a compact entity in the felling head articulated at the end of the pivot¬ able boom. The figure shows further how the two hydraulic hoses required by the pressure and return lines can enter the felling head at a point located between the cutting saw and feeding means, as seen in the longitudinal direction of the tree to be treated. The block entity of Fig. 3 is in this case mounted in its longitudinal direction so that the inlet block 7 is closest to the cutting saw 11 that is situated at one end of the felling head. Because the saw 11 is close to the inlet block 7 containing the corresponding control means, the path of the hydraulic fluid from the block to the saw will remain short, which is useful from the constructional and functional point of view. Correspondingly, at the other end of the block entity the block 9 for controlling the motors rotating the feeding means 12, and the block 8 for controlling the actuators moving the feeding means, situated immediately before the former, are both close to the corresponding actuators.

Claims

Claims :

1. Tree feeding device at the end of the pivotable boom in a tree manipulatingmachine, especially grapple harvester, said device comprising rotating feeding means driven by a feed motor (M) provided for rotation by the effect of pressure medium, a line of pressure medium (LM) being passed through said motor and being connected through two separate lines (L2, L5) to a source (P) of pressure medium and through two separate lines (L3, L6) to a return line (T) of pressure medium, said lines comprising control means for controlling the flow of pressure medium, characterized in that the control means are placed in the part carrying the feeding means and situated at the boom end and are flow control valves (2, 6, 5, 3) which are adjus¬ table in a stepless manner and of which each is connected to a pilot valve (l, 4) provided for con¬ trolling the pilot flow of pressure medium in the flow control valve for bringing about a change in the pressure medium line passing through said flow control valve.

2. Tree feeding device as claimed in Claim 1, characterized in that the flow control valves (2, 6,

5, 3) are connected pairwise (2, 6 and 5, 3) to a common pilot valve (1, 4) in such a manner that the pilot lines (ap, a^) controlling the valves of a given pair pass through the same pilot valve (1, 4) and that in this case the lines (L2, L5) between the source (P) of pressure medium and the motor (M) , and the lines (L3, L6) between the motor (M) and the return line (T) , respectively, comprise each the flow control valves for different pairs.

3. Tree feeding device as claimed in Claim 2, characterized in that the number of pilot valves is two (1, 4) , of which through the first one (1) the pilot lines (a_p, a^) for the first pair of resistance valves (2, 6) are passed and through the second one (4) the pilot lines (ap, a-_j.) for the second pair of resistance valves (3, 5) are passed.

4. Tree feeding device as claimed in Claim 3, characterized in that the pilot valves (1, 4) are 4/2-valves.

5. Tree feeding device as claimed in any of the preceding Claims 1-4, characterized in that the pilot valves (1, 4) are proportional valves.

6. Tree feeding device as claimed in any of the preceding Claims 1-5, characterized in that the flow control valves (2, 3, 5, 6) are cartridge valves, so-called valvistor cartridges, that are fixed on a valve block (9) containing the lines (L2, L3, L5, and L6) .

7. Tree feeding device as claimed in any of the preceding Claims 1-6, characterized in that the flow control valves are situated at the end of a main line (L) entering the part situated at the boom end.

8. Tree feeding device as claimed in Claims 6 and 7, characterized in that control means for the rest of the actuators in the part situated at the boom end are also accomplished using block technique, the block (9) comprising the flow control valves being situated as the last block in the flow direction of pressure medium.

9. Tree feeding device as claimed in Claim 8, characterized in that the actuator ports (Al, A2;

Bl, B2) forming pairs are provided on the opposite sides of the piece constituted of the blocks.