FI111938B - Boom control system for off-road machine - Google Patents

Description

111938

Boom control system for off-road machine

The invention relates to a pressurized fluid control system according to the preamble of claim 1 for setting a boom of a working machine for positioning it in the articulated steering mode and the direct acting mode.

In order to carry out harvesting, there are known off-road machines, such as harvesters, with a harvester head fitted at the end of the boom, so-called harvester heads for cutting, felling, and sawing the desired length of the growing tree trunk. Sawn timber trunks are collected and transported in another load compartment by another known off-road machine, i.e. a truck equipped with a loader or loader-grapple. Also known are combination machines which combine the functions of a har-15 vest and a truck. This has the advantage that logging and logging can be performed simultaneously, reducing the need for multiple machines in the forest and reducing the number of machine transfers between sites. One example of a known composite machine 20 comprising a single frame, boom and cargo space is also disclosed in US 4,984,961.

The working machines described above comprise a boom for work, which usually comprises at least three articulated boom sections, two of which move in a vertical plane. The boom 25 is attached to the implement by means of a joint to rotate the boom about a vertical direction. The same joint can also rotate the cab around the same direction, as disclosed in US 4,984,961. A suitable tool, such as a harvester head or loader grapple, can be attached to the free end of the boom to handle the load.

O ·: 30

It is important for the working efficiency of the above machines that their booms for handling, moving and loading their load are logical to operate and operate reliably and efficiently with good efficiency. In particular, a combination machine must perform as efficiently as possible in both harvester and loader work. With the present invention, this is made possible in a particularly efficient manner, whereby in the case of the boom this means that 11,1938 2 harvesters are available in so-called. Direct export features and load handling are available in the so-called. independent joint control features.

5 Booms are typically operated by a pressure medium, usually hydraulic control system, by means of actuators such as cylinders and control valves. Referring to Figure 1, one known way of controlling a pivot-type boom is to control the boom with a separate pivot-specific control valve and cylinder actuator such that the tool at the end of the boom moves at a desired location to the desired position. In order to achieve movement, the operator of the implement carries out the coordination of the control of each joint, for example by means of manual control of lever-operated valves. The valves can also be controlled automatically by electronic computer control via a machine control unit 15, whereby the driver can use joystick-type controls.

In many situations, the efficiency of joint-specific guidance is poor. When steering the boom head with a straight guide, that is, when driving it horizontally, some of the joints are made so-called. positive work against a load, or 20 gravity, and part of the so-called. However, the said control system is well suited for loading applications, for example in the treatment of timber frames, where the load is first raised from the ground to the machine's load compartment and subsequently unloaded from the load compartment to the stack. The load is thus largely shifted from one potential energy level to another, and the cycle is characterized by lifting the load and lifting the boom itself over obstacles such as the machine-loaded structure. Advantageously, in addition to the boom head, each joint can be controlled in a logical manner separately. The articulated boom of Figure 1 is a typical so-called. forwarder boom.

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Harvesters that cut, prune and cut trees have a low load lifting and lowering load compared to the horizontal movement of the boom head and tool. Mechanically-designed swamp 35 parallel bars are known to facilitate the use of the boom and improve efficiency. In these, the direct drive is often implemented by means of auxiliary boom parts and parallelogram mechanisms and, for example, the attachment of the cylinder actuators differs from the coupling 111938 3 shown in Fig. 1. Often the problem is that the horizontal movement of the boom head is straightforward only at a certain, pre-dimensioned height, and that additional boom parts increase the weight of the boom and obstruct the driver. The use of a boom for loading is impractical because the articulation 5 cannot be controlled separately.

Fig. 2 shows a known, hydraulically driven, direct-acting boom, by means of which the end of the boom performs an approximate horizontal movement at a predetermined height. In the solution shown 10 is used in principle the articulated boom structure of Figure 1, but the difference is that the cylinders are connected to one another by a control line and are controlled by a common valve. The idea of the embodiment is that, in turn, depending on the horizontal movement direction of the boom head, the pivoting cylinders operate in the negative load region, acting as a pump to move the second pivot. As a result, the actual operating pressures of the pressure medium provided by the pump acting as a pressure source for the control system in different control situations are lower than in the corresponding movement in the embodiment of Figure 1. Furthermore, due to the need for only one controllable cylinder actuator, the volume flows are also considerably smaller. This is of considerable importance to the work required by the boom: '· to P, which can be calculated by the dependence P = p · Q, where p is ... the required pump-generated pressure and Q the pump-supplied volume flow. However, also the use of this boom for loading is impractical because the joints cannot be controlled individually.

A control system according to Figure 2 is disclosed in U.S. Pat. No. 3,884,359, which further has its own control valve for each cylinder actuator. However, the control system is connected in such a way that: '30 control of the valves is carried out with three levers, so that each cylinder' L. for lowering and lifting, as well as the direct drive, have its own levers and valves. In addition, the cylinders are coupled such that, in the direct entry, the cylinders move in different directions relative to the solution of Figure 2. The problem is that the cylinders are not simultaneously controllable because their valves 35 are interconnected so that the cylinders are controlled in series when the cylinders control valves are simultaneously controlled. In addition, problem 111938 4 has a variety of unexpected and unwanted movements due to a variety of possible switching and positioning combinations of the levers.

A further practical problem in the system of Figure 2 is the reliable filling of the oil filling and venting of the control line connecting the cylinders 5. In practice, a connection to the refill oil source and a bleed valve are required. Another problem with the system of Figure 2 is how the boom head lift and lower movements are performed. It is known that the height adjustment of the boom head is effected by a separate cylinder, thus requiring one additional cylinder actuator with articulation and fastenings. This results in reliability problems and weight gain due to the complexity of the structure.

Control systems are also known which can provide both synchronized actuator movement and independent joint control. One control system is disclosed in Japanese Patent Application JP 57-195904 (Patent Abstracts of Japan, Vol. 7, No. 47, M-196). In order to provide articulated steering, each cylinder can be independently controlled by its own control valve. The auxiliary control valve allows the sy-20 cylinders to be connected in series, whereby the inferior pressure medium from the lower boom actuator is always directed to the upper actuator. The problem with said control system is poor efficiency especially in lifting, since only lowering utilizes a negative load, whereby the piston-side cylinder-25 volume of the lower cylinder of the boom is affected by the load weight and thus aids the lifting movement of the upper cylinder. Furthermore, the system is mainly applicable in situations where the purpose is to hold the load to be supported horizontally by the simultaneous movement of the actuators.

30 The solution shown in Fig. 3 is also known for carrying out a horizontal straight draw and a vertical loading movement. Boom: ··· 'head height adjustment is accomplished, like a pivot boom, by controlling a lower actuator with a control valve which also acts as a bleed valve for the control line connecting the cylinders. Both direct actuators and a second control valve are still used for direct actuation, i.e. horizontal movement, with the lower boom actuator connected to both control valves. The design of the overall control system 111938 5 takes into account the load level of the actuators, in particular the pressure level in the connecting line, so that the solution operates reliably and logically. However, the weakness of image coupling is the possibility of unwanted movements in lifting and lowering movements. For example, when performing 5 lifting movements at a large boom reach, an unwanted folding of the outermost boom portion down the upper joint is possible because the load and load pressure level of the upper boom actuator is greater than the pressure required by the lifting medium in the lower actuator piston.

The undesirable movement described above can be prevented, for example, by dimensioning the actuators and the boom geometry in which the lower actuator piston pressure level is always higher than the upper actuator piston rod pressure level. One solution is to connect a valve in the line connecting the actuators to prevent unwanted movement of said upper actuator while driving the lifting movement. A suitable valve for this purpose is e.g. a load lowering valve which is known in part e.g. However, the problem of reducing the usability of the solution is that the cylinder actuators and hence the boom joints cannot be controlled independently of each other, and thus the control system is only applicable to harvester machines.

25

One control circuit for a work machine is also disclosed in US 4,828,125, but it is not possible to control the boom actuators individually by means of such control circuit.

It is an object of the present invention to eliminate the limitations of the above solutions and to provide a working machine boom control system having the advantages of a self-steered articulated boom and a direct acting boom. The work machine, especially the combination machine mentioned, in which the control system of the invention is applied to control the boom, is suitable for both harvesting and loading of wood-35. To accomplish this purpose, the control system of the invention is characterized by what is set forth in the characterizing part of claim 1.

111938 6

The invention is based on the implementation of both autonomous control of the actuators of the boom joints and their direct actuation by very simple means. The invention is further based on the idea that, in order to reduce pressure and improve efficiency, depending on the direction of movement, each joint actuating cylinder actuator operates in the negative load region while acting as a pump to move the other joint.

The invention provides considerable advantages such as simplicity and hence ease of use and reliability, in which, according to a preferred embodiment of the invention, only two control valves and two cylinder actuators are used. A good efficiency is achieved by assisting the load with both directions of movement while at the same time achieving a low volume flow and lower operating pressures. The steering system is flexible and the implement operator can, for example, work logging in the articulated mode or loading in the direct export mode according to his preferences and habits. Em. the modes are selectable in the invention for clarifying the operation of the control and for implementing the control with only two controlled valves.

: In a preferred embodiment of the invention, the logic valves used are simple, reliable, and inexpensive, ready-made components. It is advantageous to place all logic valves in the same 25 valve blocks, thus providing a compact and reliable design. Other valve functions that may be used in the system, such as, for example, regenerative and load-lowering functions, can also be placed in the same block as needed.

The invention will now be described in more detail using, by way of example, a preferred embodiment of the control system of the invention, with reference to the accompanying drawings, in which: Figure 1 shows a prior art boom control system 35 and articulated control; Fig. 3 is a plan view of a prior art boom control system and a boom control and vertical motion control, and Fig. 4 shows a boom control system according to a preferred embodiment of the invention and a boom in which the invention can be applied.

A machine for moving and transporting trees in the terrain usually comprises at least one frame member arranged to be movable, for example, by means of wheels connected to the frame member by bogies. A power source for the work machine, typically a diesel engine, is also housed in the body, and the machine is equipped with a mechanical hydrostatic transmission system. The two frame sections allow the implement to be arranged in a frame-guided manner. It is also possible to mount a swivel base on which the cab 20 is also located, and to which the boom can also be mounted.

Figures 1-4 show a simplified diagram of the boom, cylinder actuator mountings and articulation. For example, the halves are shown as straight structures, but it is clear that their more precise structure and shape can vary widely. In addition, the joints are represented by simplified hollow circles. In addition, in order to illustrate the operation, the actuators are attached by means of a joint to the projections secured to the boom section, but it will be appreciated that in many cases said joint may also be located directly in the half section.

The boom of Fig. 1 comprises a first boom section P1 which comprises a first end P1a and a second end P1b usually fixedly fixed to the implement. The attachment of the first end P1a can also be mounted on a platform rotating about a vertical axis, whereby the boom can be pivoted sideways. The boom part P1 is usually vertical and is arranged to rotate in vertical steps Z around 111938 8. The boom comprises a second boom section P2 comprising a first end P2a secured by a joint to one end P1b of a first boom section P1 and a second end P2b. The other end P2b is generally arranged in a vertical (plane Z-X) plane 5 to rotate about the joint of head P2a. Rotation is achieved by a first cylinder actuator S1 secured between the first boom member P1 and the second boom member P2. The boom further comprises a third boom member P3 comprising a first end P3a secured by a joint to one end P2b, 10 of the second boom member P2 and a free second end P3b. The other end P3b is arranged in a generally vertical (plane Z-X) plane to rotate about the joint of head P2b. The rotation is achieved by means of a second cylinder actuator S2 secured between the second boom part P2 and the third boom part P3.

15

Further, the outer boom member P3 may be arranged telescopically operable to extend the boom reach. At the free end P3b of the boom, a harvester head known per se can be fitted to perform cutting and felling of the growing tree, cropping and felling of the tree trunk, loading and unloading the tree trunks; load space. It is clear that a loader equipment known per se, which is used only for loading the trunks, or a harvester head, which is used only for cutting and felling growing tree, and for pruning and trimming the tree trunk, can be connected to the end of the boom.

25

Referring to Figure 1, actuator S1 (i.e., from joint P1b to P2a) is controlled by control means V1, such as control valve V1 and control lines L1, L2. The control means V2, such as the control valve V2 and the control lines L3, L4, control the actuator S2 (i.e. from the joint P2b to P3a). For example, to extend the actuator S1 and at the same time raise the other end P2b, the line L1 is connected to the pressure line P and the line L2 is connected to the return line T by means of a control valve V1. In order to shorten the actuator S1 and at the same time lower the second end P2b, the line L2 is connected to the pressure line P and the line L1 is connected to the return line T by means of a control valve V1. The Oh-35 distribution valves, such as valves V1 and V2, communicate with the control system pressure source P and the return line T, such as a tank line whose pressure level is usually lower than the pressure source P. The control system may include other components known per se, tank means for preserving pressure medium, filter means, pressure control means for setting the pressure level, and pump means acting as a pressure source for generating pressure and 5 volumes.

Fig. 2 shows a known solution whereby the end P3b of the boom of Fig. 1 provides at least an approximate horizontal straight feed (arrows X1 and X2) at a certain height Z. Actuator S1 cylinder volume S1a is coupled by connecting control line PK to actuator cylinder S2b. The other cylinder volumes S1b and S2a are connected to the control valve V1 so that the pressure line P and the return line T can be alternately connected thereto. When moving P3b in direction X1, the pressure source P is connected to volume S2a and actuator S2 acts as pump and actuator S1. The volume flow of pressure medium, usually hydraulic fluid, moves from volume S2b to volume S1a and volume S1b with control valve V1 connected to return line T. When moving P3b in direction X2, pressure source P is alternately connected to volume S1b and actuator S1 acts as pump and actuator 20.

In Fig. 3, the displacement of the head P3b in the vertical direction (arrow Z), i.e. the movements ... Z1 and Z2, is effected by controlling the actuator S1 with the control valve V1.

For actuation, i.e. horizontal (arrow X) movements X1, X2, both actuators S1 and S2 and control valve V2 are used.

Figure 4 shows a first preferred embodiment of a control system according to the invention. In the control system, the rotation of the boom members is arranged such that as the actuator S1 elongates, the end P2b rises and, as the actuator S2 elongates, the end P3b decreases and the end P3b rises.

In another preferred embodiment of the invention the coupling of the actuators is such that as the actuator S1 elongates, the end P2b decreases Λ 35 and as the actuator S2 elongates, the lateral control line L5 connecting the actuators S1 and S2 in series S1 and the volume S1 of the actuator S1 111938 10, whereby the control line L6 to be described later must be connected to the volume S1a of the actuator S1. The control line L3 is connected to the volume S2b. A common principle for the first and second embodiments is that in the direct insertion the cylinder actuator S1 and the cylinder actuator S2 are arranged to be movable in the same direction, so that they are either shortened or elongated.

In a third preferred embodiment of the invention the coupling of the actuators is such that as the actuator S1 elongates, the end P2b decreases 10 and as the actuator S2 elongates, the end P3b decreases, thus also controlling control line L5 to be described between actuator S1 volume S1b and actuator S therefore, the actuator S1 must be coupled to the volume S1a. The control line L3 is connected to the volume S2a.

15

In a fourth preferred embodiment of the invention the coupling of the actuators is such that as the actuator S1 elongates the end P2b and as the actuator S2 elongates the end P3b, also the control line L5 described below is to be coupled between actuator S1 20 and S1a; The control line L6 described below must therefore be connected to the volume S1b of the actuator S1. The control line L3 is connected to the volume S2b. A common principle for the third and fourth embodiments is that the cylinder actuator S1 and the cylinder actuator S2 are arranged to move in different directions in the direct mode.

However, it is a common principle that in the direct delivery, the boom part P2 and the boom part P3 are arranged to be simultaneously rotated in opposite directions under the control of the control valve V2.

30

The movement of the boom is controlled by two control valves V1; · And V2. The genitals V3, V4 and V5 have provided for opening and closing the control lines. According to a preferred embodiment of the invention, the genitalia are as such implemented by means of logic valves (Logic 35 Element) which may also comprise a hydraulic pre-steering part. Preferably, the valves are electrically operated, whereby in their normal position they are either closed or opened and, when electrically operated, move to another position. The valves are preferably controlled by a machine control system CTRL which comprises, for example, a control computer. For example, the user informs the control computer of the state in which the control system must be located, for example by means of a switch. The genital V3, V5, V4 and V5 select the boom control state, the states comprising independent articulation of the joints of the boom and a direct or parallel port. Referring to Figure 4, in articulation control V3 is open (no steering), V4 is closed (no steering), and V5 is closed (no steering). In the direct outlet, V3 is closed (control), V4 is open (control) and V5 is open (control). It is clear that two or more genitals V3-V5 may also be formed on the same valve, such as an electrically controlled 2-way directional valve. For safety reasons, the genitals V3, V4 and V5 are preferably arranged so that, in the absence of control, they place the boom control in a position where independent joint control is possible. In this case, the genitalia V3, V4 and V5, for example by means of a spring control, move to a certain position according to Fig. 4 for said space. The control may be missing, for example, in the event of a power failure or other malfunction.

20 In the articulated control, the control system functions like the control system of Figure 1j and the operation of the valves V1, V2 in Figures 1 and 4 correspond to each other. In this state of control, control line L6 is closed by genital V5, control line L4 is opened by genital V3, and control line L5 is closed by genital V4. In said control 25, the ends P2b and P3b can be controlled independently and by different valves.

When moving the head P3b in direction X2, the pressure source P is connected (using control line L6) to volume S1b with valve V2 (open valve V5) and to control volume flow from volume S1a it is connected (using control line L5) to volume S3b by genital organs V4. The volume flow is controlled from volume S2a by control valve V2 to return line T. When moving P3b in direction X1, pressure source P is switched to volume S2a by valve V2 and to control volume flow from volume S2b it is connected to volume S1a 35 by genital V3. The volume flow is controlled from volume S1b by the control valve V2 to the return line T (genital V5 opened). In this state, height adjustment in directions Z1 and Z2 is effected by 111938 12 with valve V1 for switching head P3b in direction Z1 to volume S1a to pressure source P and volume S1b to return line T, and to shifting head P3b in direction Z2 to volume source P1 L6 is connected to 5 control lines L4, whereby control valve V2 can be implemented with a 3-position 4-way valve. The valves V1 and V2 shown comprise a closed center position for closing lines L1 to L4. Both valves V1 and V2 may also be direction proportional valves to perform the function illustrated. Preferably, the valves are electrically controlled and control valves communicating with the control unit 10 CTRL, which are controlled by the controls C1 and C2. Also said controllers may communicate with a control unit CTRL which controls the control means V1 and V2 based on the position of the controllers.

The invention is not limited to the above embodiment, but may be modified within the scope of the appended claims. For example, two or more shut-off members V3-V5 may also be formed on the same valve, such as an electrically controlled 2-way directional valve. It will also be understood that the guide lines L1 to L6 may be implemented by tubes and hoses known per se, and at least in part i by forming the necessary guide lines in the control block B into which said guide lines are drilled. Preferably, said cartridge-type Logic Valves V3-V5 are also placed in the bores. In the above description, the cylinder volume refers to one of the two volumes of the cylinder actuator, i.e. either the piston side or the piston rod side. The connection of the two cylinder actuators shown in the four different embodiments of the invention to the boom varies, and thus the control system is different, meaning that when the first cylinder volume is piston volume, the second actuator volume is the piston rod volume. Likewise, with the first cylinder volume being the piston rod volume, the second actuator is driven by the second actuator. 'Cylinder volume' refers to the piston-side volume.

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Claims (10)

111938 13 1 I 'I - a second cylinder actuator (S2) attached between the second boom section (P2) and the third boom section (P3) arranged to move the second end (P3b) of the third boom section (P3) in a substantially vertical plane (plane Z-X). , I *: - first control means (V1) communicating with the pressure source (P) and the return line (T) arranged to direct the pressure medium through the first control line (L1) 35 to the first cylinder volume (S1a) of the first cylinder actuator (S1); via a guide line (L2) to a second cylinder volume (S1b), 111938 14 - a second control means (V2) communicating with the pressure source (P) and the return line (T) arranged to control the pressure medium via the third guide line (L3) to the second cylinder actuator; (S2) to the first cylinder volume (S2a) and alternatively through the fourth guide line (L4) to the second cylinder volume (S2a) S2b), and - third closing members (V3) fitted to the fourth guide line (L4) for closing and opening the fourth guide line (L4), - a fifth guide line (L5) arranged to guide the pressure medium to the first cylinder actuator (S1) 15; between the cylinder volume (S1a) and the second cylinder volume (S2b) of the second cylinder actuator (S2b) in the direct export mode, wherein the second boom part (P2) and the third boom part (P3) are arranged simultaneously rotated in opposite directions by the second guiding means (V2). II: * ·· - first closing means (V4) fitted to the fifth control line (L5) to close, j 'open and open said fifth control line (L5), and t I »; i * 25 - a sixth control line (L6) arranged at a pressure interval i .1. for guiding material between the second control means (V2) and the second cylinder volume (S1b) of the first cylinder actuator (S1), characterized in that the control system further comprises second closure means (V5) disposed on the sixth control line (L6) for closing the sixth control line (L6). and to actuate the cylinder actuators (S1, S2) independently in the articulated steering mode, the cylinder actuators (S1, S2) being further connected to the boom members (P1, P2, P3) such that the first cylinder volume (S1a) of the first cylinder actuator (S1) ) is arranged to support a positive load which tends to reduce this cylinder volume (S1a) and is caused by the weight of at least one boom member (P2), and that the second cylinder volume (S2b) of the second cylinder actuator (S2) is arranged to support a positive load to reduce this cylinder volume (S2b), and caused by the weight of at least the third boom section (P3). A pressurized fluid control system for a working machine boom 5 for positioning it in a pivot control and direct delivery mode comprising at least - a first boom section (P1) attached to a first end (P1a) of the machine, 10 - a second boom section (P2) secured to the first boom section (P1) a first end (P2a) and a second end (P2b), and a third boom member (P3) attached to the second boom member (P2) by a joint, comprising a first end (P3a) and a second end (P3b), and the control system comprising 20 • A first cylinder actuator (S1) mounted between the first boom member (P1) and the second boom member (P2) arranged to actuate the second end (P2b) of the second boom member (P2) in a substantially vertical plane (plane V 25 Z— X) Control system according to claim 1, characterized in that in the articulated steering mode the first closing element (V4) is closed, the second closing element (V5) is closed and the third closing element (V3) is opened, in which positions these closing elements (V3, V4, V5) are also arranged. in the absence of control, and that in direct mode 15 the first closure member (V4) is open, the second closure member (V5) is open and the third closure member (V3) is closed. A control system according to claim 2, characterized in that in the direct-acting mode, the first closing member (V4) open, the second closing member (V5) open and the third closing member (V3) closed the first cylinder actuator (S1) is arranged to reduce and extend the height adjustment for. Control system according to claim 2 or 3, characterized in that a portion of said fourth control line (L4) disposed between the second control means (V2) and the third closing element (V3) and said sixth control line (L6) are connected to each other. Control system according to one of claims 2 to 4, characterized in that the first closing element (V4), the second closing element (V5) and the third closing element (V3) are each formed by a 2/2-cartridge valve. Control system according to any one of claims 1 to 5, characterized in that, when elongated, the first cylinder actuator (S1) is arranged to move one end (P2b) of the second boom part (P2) upwards or downwards and that the second cylinder actuator (S2) 111938 16. is arranged to move one end (P3b) of the third boom part (P3) up or down. Control system according to one of claims 1 to 6, characterized in that said machine is a machine for moving and transporting trees in the terrain and that a tool acting as a loader and / or harvester head is attached to one end (P3b) of the third boom part (P3). . Control system according to any one of claims 1 to 7, characterized in that said implement comprises a computer-controlled control unit (CTRL) for setting the control system into a articulated steering mode and a direct drive mode. Control system according to any one of claims 1 to 8, characterized in that it comprises a first control lever (C1) and a second control lever (C2), wherein the first cylinder actuator (S1) is arranged to be controlled by the first control lever (C1) and the second cylinder actuator (S2) is arranged to be controlled by a second control lever 20 (C2), and in direct mode, both cylinder actuators (S1, S2) are arranged to be controlled by a second control lever (C2) to cause horizontal movement (X1, X2) and a first control lever (C1). controlled to cause vertical movement (Z1, Z2). V 25 Control system according to one of claims 9 to 9, characterized in that the first control elements (V1) and the second control elements (V2) are each formed by a proportional directional valve. 111938 17