FI122922B - Process in a pressure medium system which uses and controls a special boom boom system in connection with a working machine - Google Patents

Description

A method especially for a pressurized fluid system using and controlling a lifting boom connected to a work machine.

The invention relates to a method according to the preamble of claim 1, which is specifically intended for use in connection with a pressure medium system which uses and controls a lifting boom.

A lifting boom applying the method according to the invention typically comprises a substantially vertical frame boom, to which a nive-10 is loosely coupled with an intermediate boom. To this intermediate boom is further connected an articulated top boom, to which a load, working machine, etc., which can be moved by a lifting boom, can be attached. Such a hydraulic lifting boom is operated by two cylinder-piston combinations, wherein the first cylinder-piston combination connecting the frame boom and the intermediate boom provides 15 substantially vertical movement and the substantially horizontal movement with the first-bar and piston-rod joint. In the conventional solutions, the cylinder-piston assembly of the lifting boom is controlled by separate operating valves belonging to the control unit 20 via a hydraulic fluid pressurized in a pressure unit supplied through independent primary and secondary lines.

The lifting boom of the above-mentioned type is used such that when moving, e.g. The weight 30 of the load exerts a certain amount of pressure on each cylinder-piston assembly. When moving the load away from the frame boom, the control of the first cylinder-piston assembly does not require pressure from the pressure unit due to the effect of gravity, while full pressure is required to control the second cylinder-piston assembly. Thus, the operating pressure of the hydraulic system 35, in which the cylinder-piston assemblies are connected to the hydraulic system according to the state of the art, with flow channels completely separate from one another, is always determined by the highest required pressure. For this reason, if both cylinder-piston assemblies are the same size, half of the energy produced by the pressure unit is always converted to heat loss. In addition, the cylinders 5 have very easy cavitation due to the high pressure exerted on the return ports of the cylinder-piston combinations due to the load and the weight of the lifting boom itself, and the inlet ports are unable to supply a sufficient amount of pressure medium through the valve arrangements. Furthermore, the use of a lifting boom, particularly in horizontal movements of load or the like, is difficult, since this requires the use of both cylinder-piston combinations, which are controlled separately but simultaneously by two actuating valves.

It is an object of the method of the present invention to provide a decisive improvement on the above problems and thereby substantially improve the state of the art. To achieve this object, the method according to the invention is essentially characterized in what is set forth in the characterizing part of claim 1.

The main general advantages of the method according to the invention are its simplicity, reliability and efficiency. The method can be used to make even very massive assemblies 25, compared to conventional solutions with lower power units and cylinder-piston combinations. At the same time, it is possible to reduce the amount of pressurized medium to be recycled, up to half the current solutions. Because, particularly in lift boom applications, the forces and moments applied to the lift boom from the cylinder-piston combinations are significantly reduced compared to the present ones, the design of the lift boom can even be somewhat simplified and lightened if necessary. The process of the invention thus also has the advantage here, in particular, of significantly improving efficiency and drive efficiency over current processes. Other advantages of the method according to the invention include the easier controllability of the pressure medium system, whereby the method does not usually require the control of two separate cylinder-piston assemblies with separate actuators. In addition, the method of the invention makes it possible to significantly reduce cavitation problems.

Advantageous embodiments of the method of the invention are disclosed in the dependent claims.

In the following description, the invention will be illustrated in detail with reference to the accompanying drawings, in which Figure 1 shows a preferred schematic diagram of a pressurized fluid system operating according to the method of the invention and Figure 2 illustrates a side elevation of a preferred method.

The present invention relates to a method in a pressure medium system comprising at least two pressure medium actuated cylinder-piston assemblies 20 1.2 (hereinafter actuators), a pressure unit P such as one or more pumps for pressurizing the pressure medium and a control unit V comprising a valve arrangement 4,5 2 is applied by passing the pressurized pressure medium to their respective pressure spaces and respectively displacing the pressure medium 25 from their respective pressure spaces. In order to enhance the operation of the pressure medium system, especially in the simultaneous operation of the actuators 1,2, the actuators 1,2 are switched to operate in a so-called. in a series such that the displaceable pressure medium is led from one of the actuator 1/2 to the depressurized pressure chamber to the second actuator 2/1 to be filled to a pressurized pressure space. The pressure medium is returned to the control unit V from the depressurized pressure state of the second actuator 2/1.

The method according to the invention is preferably applied in accordance with the principle of Fig. 1 in a pressure medium system comprising two actuators 1,2 controlled by two actuators 4, 5 of the control unit V to a flow arrangement such as primary 6a, 7a and secondary 6b, 7b. via a pressure medium passed through. When at least actuators 1,2 are used simultaneously 4, the pressure medium is supplied by a control unit V, such as a first or second actuator valve 4/5, to one actuator such as a first or second pressure cylinder 1/2, from which the displaceable pressure medium is further supplied to the next actuator 2/1. V.

With particular reference to the operating principle of Figure 1, the pressurized medium is conveyed by the actuators 1,2 when simultaneously operated by a control unit V, such as a primary actuator 5A of a second actuator valve 5 to a or C1 for the second pressure space D2 to be filled by the second actuator 2. The pressure medium is then returned from the first pressure chamber D1 to be discharged by the second actuator 2 to the control unit V, such as the secondary port 5B of the second actuator valve 5.

In the opposite operation of the pressure medium system, when actuators 1, 2 are simultaneously used, the pressure medium is led by the control unit V, i.e. from the secondary port 5B of the second actuator 5 to the first pressure state D1 of the second actuator 2 . The pressure medium is then returned from the second pressure space C2 of the first actuator 1 to be discharged to the control unit V, i.e. to the primary port 5A of the second actuator valve 5.

As a particularly advantageous application environment of the method, reference is made to Figure 2, which shows the so-called. pressure medium-30 system in connection with the lifting boom. Such a hydraulically operated lifting boom X, which is located in connection with a working machine such as a tractor, forestry machine or excavator, comprises a substantially vertical frame boom X1 which is connected to the working machine is an articulated joint at its other end with a crane boom X3 at its first end, the bodies of which at its other end are movable by means of a lifting boom, a tool, etc., which can be moved. The lifting boom 5 is preferably operated by two cylinder-piston assemblies 1,2 (hereinafter actuator), the first actuator 1 connecting the frame boom X1 and the intermediate boom X2 to provide substantially vertical movement of one end of the top boom X3 and a correspondingly parallel a second actuator 2 connecting the intermediate boom X2 and the top boom X3 together with said first actuator 1. In this type of application, the method according to the invention is utilized when actuators 1,2 are used simultaneously, e.g., in horizontal displacements of 10 lifting boom heads such that the displacement energy of pressure medium fed to the first actuator 1 is utilized to operate the second actuator 2. ; a second part 711 of a second actuator 2 to a secondary conduit 7a, en-15, to a second conduit 1b for a pressure medium C2 and a second part 711 of a primary conduit 7a to a primary conduit 6a for the first pressure cylinder 1 Thus, the length changes of the actuators 1, 2 are parallel.

20

A further preferred embodiment is the supply of pressure medium from the primary port 5A of the actuator valve 5 to the inflatable pressure space C2 of the first actuator 1. Similarly, the pressure medium C1 of the first actuator 1 exits the pressure medium D2 of the second actuator 2, after which the pressure medium returns to the secondary port 5B of the second actuator 5 only after the pressure medium D1 of the second actuator 2. The above process corresponds, for example, to the outward movement of the load at the end of the lifting boom, whereby, while the intermediate boom X2 rotates downwards, it pushes one end of the top boom X3 away from the frame boom X1. In applying the method, the weight of the load exerts a substantially equivalent pressure on both actuators 1.2. In this context, it is still possible to obtain suitable actuator ratios with suitable volumes of actuators, in particular with a view to facilitating substantially horizontal movements. Therefore, optimum low pressure is required for utilizing the pressure medium system according to the invention, since the pressure of the lifting actuator 1 directly drives the second actuator 2. For the same 6 reasons, the required amount of oil is also minimized since it is supplied only to the first actuator 1.

When the load is transferred to the frame boom X1, the pressure medium 5 is respectively supplied from the secondary port 5B of the second actuator valve 5 to the inflatable pressure space D1 of the second actuator 2. The depressurized pressure space D2 of the second actuator 2 exits the pressure actuator C1 of the first actuator 1 correspondingly to the pressure medium. The hydraulic fluid then returns from the depressurized pressure chamber 10 C2 of the first actuator 1 to the primary port 5A of the second actuator valve 5. Here too, the operating pressure required is kept to a minimum, since the intermediate boom X2 exerts a pressure on the actuator 2 and thus tends to extend the first actuator 1. Again, the amount of oil to be recycled is half that required by conventional systems.

15

1 and 2, the upward rotation of the intermediate boom X2 can advantageously be carried out by applying pressure medium through the output port 1, i.e. primary port 4A of the first actuator valve 4, to the first pressure space C1 of the first actuator 1. When the second actuator valve 5 is closed, the first pressure chamber D1 of the second actuator 2 is also closed, and thus the second actuator 2 cannot move even though its second pressure space D2 is affected by pressure. Correspondingly, the simple downward movement, i.e. the downward rotation of the intermediate boom 25 X2, is performed in the reverse order by supplying hydraulic fluid via the secondary pressure port C2 of the first actuator 4 to the second pressure space C2 of the first actuator 1, respectively. Again, the second actuator valve 30 is closed and no pressure is applied elsewhere. In order to stabilize the aforementioned functions, the flow chart shown in Figure 1 also includes, as a conventional application, a so-called. a load lowering valve 3 which prevents the second actuator 2 from being accidentally moved.

35

It will be appreciated that the actuator valves 4 and 5 may also be operated simultaneously, wherein the movement of the lifting boom is a composite motion including the motion components selected as required by the above functions of the first actuator 7 and the second actuator 5 as described above. Thus, the method according to the invention provides an easily controllable so-called. the possibility of directional movement and the fact that, if necessary, the trajectories can be carried out completely freely. These versatile functions are controlled by only two actuators 4.5.

Claims (4)

A method of a pressure medium system which uses and controls a lifting system existing in connection with a working machine, the lifting system (X) comprising: - a substantially vertical frame boom (Xl), the first end of which is fixed to the working machine, - an intermediate boom (X2) which at its first end has been connected to the other end of the frame boom (XI) by means of a hinge connection, and - a top boom (X3) which at its first end has been connected to the other end of the intermediate boom (X2) by means of a hinge connection, at the other end of which the top boom has been formed means for securing assemblies needed for the working performance of the lifting boom (X), the pressure medium system comprising: - a first cylinder-piston combination (1) that works with pressure medium between the frame boom (X1) and the intermediate boom (X2) to achieve substantially vertical movements of the other end of the top boom (X3), - a second cylinder-piston combination (2) which works with pressure medium between the intermediate boom (X2) and the top boom (X3), in combination with the first cylinder-piston combination (2) operating with pressure medium, causes substantially horizontal movements of the second end of the top boom (X3), - a pressure unit (P) for providing the pressure medium with pressure, and - a control unit ( V) comprising a first and a second control valve (4, 5) for guiding the pressurized pressure medium to the pressure spaces (C1, C2; D1, D2) on the first and second cylinder-piston combinations (1,2) and out of them to effect a desired movement of the second end of the top boom (X3), whereby in the application of the method: A) a pressure medium flow is controlled via the first the actuating valve (4) to the first cylinder-piston combination (1) to effect substantially vertical movements of the second end of the top bar (X3), - the first and second cylinder-piston combination (1,2) are connected in series to achieve substantially horizontal movements of the second end of the top boom (X3), whereby B) a pressure medium flow is controlled via the second actuating valve (5) to the first cylinder-piston combination (1), with whose pressure effect as the pressure space is filled the pressure medium is moved from the pressure space of the first cylinder-piston combination (1). is discharged into the pressure space of the second cylinder-piston combination (2) which is filled or vice versa, and 12 - a combined movement is carried out comprising substantially vertical and horizontal movement components of the other end of the top boom (X3), by simultaneously applying functions A) and B), characterized in that in order to accomplish functions A), B) and A) & B) - a primary port (4A) for the first actuating valve (4) to a first pressure space (C1) on a first actuator (1) and a secondary port (4B) to a second pressure space (C2) on the first actuator (1), and - a primary port (5 A) for the the second control valve (5) is coupled to the second pressure space (C2) of the first control device (1) and a secondary port (5B) to a first pressure space (D1) of a second control device (2), and - a second pressure space (D2) of the second the actuator (2) is coupled to the first pressure space (C1) of the first actuator (C1). Method according to claim 1, characterized in that - the secondary port (5B) of the second control valve (5) is connected to the first pressure space (D1) of the second control device (2) via a load lowering valve (3). Method according to claim 1, characterized in that - the second pressure space (D2) of the second control device (2) is connected to the first pressure space (C1) of the first control device (1) via a load lowering valve (3). Method according to claim 1, characterized in that in order to effect the series connection, a first part (71), ie. a portion connecting to the second actuating valve (5), on a primary line (7a) for the second cylinder-piston combination (2) to a secondary line (6b) for the first cylinder-piston combination (1) and a second portion (711), i.e. a portion connecting to the second cylinder-piston combination (2), on the primary conduit (7a) of the second cylinder-piston combination (2) to a primary conduit (6a) for the first cylinder-piston combination (1).