EP1639205A1

EP1639205A1 - Device for a mechanical digger

Info

Publication number: EP1639205A1
Application number: EP04748760A
Authority: EP
Inventors: Per Jorgen Myhre
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-06-23
Filing date: 2004-06-23
Publication date: 2006-03-29
Also published as: WO2004113622A1; NO20032876D0; WO2004113622B1; NO320025B1; NO20032876L

Abstract

A device for a mechanical digger (10) is described, where the mechanical digger comprises a lower drive machinery (12) and an upper rotational part (14), where a lifting beam is connected to the upper part (14) comprising a vertically rotational lifting arm (18) which is articulately connected to an intermediate arm (20) to which a digging/lifting tool is articulately fitted, and a number of cylinders (24,26,28) arranged to drive the lifting beam. One or more of said cylinders for raising and lowering of the lifting beam comprises a multicylinder (24) for hydraulics and gas, where the gas part of the multi-cylinder (24) is arranged to provide a counter-force which approximately corresponds to the downward directed force vector of the lifting beam.

Description

DEVICE FOR A MECHANICAL DIGGER

The present invention relates to a device for a mechanical digger, where the mechanical digger comprises a lower driving machinery and an upper rotational part, and a lifting beam connected to the upper part, comprising a vertical rotational lifting beam that is articulately connected to a digging arm to which a digging/lifting tool is articulately fitted, and pressure cylinders arranged to drive the lifting beam.

Today, mechanical diggers normally use a diesel engine to drive the machine and to drive the hydraulic pressure cylinders on the mechanical digger. During scooping out and unloading, the beam of the mechanical digger is often lifted twice a minute in normal operation. This means that a great deal of fuel is used during the different work cycles. For a large mechanical digger, for example of 40 tonnes, with an engine of 300-400 HP, it is clear that the fuel consumption is high during a working day, and not to mention, during one year. By using the present invention, one will not only save large sums because of reduced fuel consumption, but the discharges of harmful gases will conseguently also be reduced considerably. So that by using the invention, both an economic and an environmental gain will be achieved.

The object of the present invention is to provide a system which makes the lifting beam of the mechanical digger, i.e. the digging unit, as weightless as possible. To achieve this, a multi-cylinder with a gas lifting function can be fitted to the mechanical digger's lifting beam. The advantage with this is, among other things, that energy (fuel) is saved. During scooping out and unloading, the beam is, as mentioned, lifted about twice a minute. The larger the machine is, the larger the beam that has to be lifted, and the more diesel fuel to be saved.

This object is achieved by the present invention, as defined in the characteristic part of claim 1, in that one or more of the cylinders for the raising and lowering of the lifting beam is comprised of a multi-cylinder for hydraulics and gas, where the gas part of the multi- cylinder is arranged to provide a counter force which approximately corresponds to the downwardly directed force vector of the lifting beam.

Preferred embodiments of the invention are characterised by the dependent claims 2-6.

The invention shall now be explained in more detail with the help of the enclosed drawings in which: Figure 1 shows a mechanical digger comprising a multi- cylinder according to the present invention. Figure 2 shows a section of an embodiment of a multi-cylinder according to the invention.

Figure 3 shows a section of another embodiment of a multi- cylinder according to the invention.

Figure 4 shows a section of another further embodiment of a multi-cylinder according to the invention. Figure 5 shows a section of another further embodiment of a multi-cylinder according to the invention.

Figure 1 shows a mechanical digger 10 according to the invention comprising a lower part 12 with a driving machinery such as caterpillars or wheels, and an upper part 14. The upper part 14 can comprise an engine and possibly also a driver's cab 16.

The expressions vertical and horizontal are used in this description. With this is meant a normal plane that is vertical and horizontal, respectively, in relation to the mechanical digger and is not dependent on the position of the mechanical digger itself on the terrain.

Connected to the upper part 14 is a lifting beam which comprises a lifting arm 18 that is vertically rotationally connected to the upper part 14, the lifting arm can also possibly be rotational around a vertical axis. The lifting arm is articulately connected to an intermediate arm, such as a digging arm 20, where the lifting arm and the digging arm in co-operation are arranged to lift and to move a shovel 22, or other equipment, to a desired position with the help of fitted cylinders, such as for example, a first cylinder 24, a second cylinder 26 and a third cylinder 28. The pressure cylinders 26 and 28 are fitted in a way known to one skilled in the art, and will therefore not be further described. One or more cylinders 24 in the form of a multi-cylinder, can be fitted between an outer point on the lifting arm 18 and a central area on the upper part 14, where this area can be centred around the middle section or point of gravity of the upper part. It is preferred that one or more multi-cylinders 24 are fitted in a conventional way, i.e. between an inner point on the lifting arm and a forward point on the upper part (as shown in figure 1) . A multi-cylinder 24 can be used on one or both sides of the lifting beam, or a multi-cylinder 24 which is placed centrally in the lifting beam can be used.

To lift and to move the lifting beam, i.e. the lifting arm, digging arm and the shovel, the multi-cylinders 24 are used, as mentioned. The object of the multi-cylinder 24 is to make the lifting beam, i.e. the lifting arm and the digging arm, as "weightless" as possible. The fuel consumption is reduced in that the cylinders, which are normally driven hydraulically, do not have to lift the weight of the beam. During loading, the beam is raised about 2 times a minute during normal use. So that the larger the machine, the larger is the lifting beam that shall be lifted and the more fuel can be saved. In the main, the multi-cylinder 24 encompasses a cylinder comprising a number of working chambers for both hydraulics and gas, and which shall function as a counterweight to the lifting beam.

The system also gives the machine extra strong beam lifting ability, as the power of the machine is not used to lift the beam itself.

Different examples of a multi-cylinder 24 will be described below.

One embodiment of the multi-cylinder 24 is shown in figure 2. This embodiment comprises three working chambers 1, 2 and 3, for gas and hydraulics, respectively. The multi- cylinder 24 comprises an outer cylinder 150 and an inner cylinder 140, where a piston rod 144 with a piston 142 is arranged in the inner cylinder 140. The working chamber 3 is constituted mainly of the inner of the inner cylinder 140 but also of an area adjoining the first end 130 of the multi-cylinder, which is provided when the inner cylinder 140 is moved out of the outer cylinder 150. The working chamber 1 is arranged for supply of gas under pressure and will thereby contribute to lifting of the lifting beam. The gas can be supplied/evacuated by way of one or more channels 132 at the first end 130 from/to an accumulator (not shown) arranged adjoining the multi-cylinder 24, or the accumulator can be arranged centrally on the mechanical digger for supply to all the multi-cylinders, if more than one is used.

The working chambers 2 and 3 are arranged to be controlled by hydraulic oil, for lifting and lowering of the lifting beam. Working chamber 2 is preferably used for lifting of the lifting beam, and hydraulic oil is supplied to/withdrawn from the chamber by way of one or more channels 134 adjoining the other end of the multi- cylinder. Working chamber 3 is preferably used to lower the lifting beam, and supply/withdrawal of hydraulic oil can be carried out by way of one or more channels 136.

Figure 3 shows a section of a multi-cylinder according to the invention. The cylinder, or cylinders, can be fitted as described above. The multi-cylinder comprises a first cylinder 40, to which a movable piston 42 that is permanently fastened to a piston rod 44, can be moved vertically in the cylinder 40. The piston defines two working chambers 1 and 2 in the first cylinder 40. In the lower part of the cylinder 40, is an inlet/outlet opening to regulate the supply/withdrawal of pressure medium in the working chamber 2.

For the supply/withdrawal of pressure medium to the first working chamber 1 in the upper part of the first cylinder 40, the piston rod 44 comprises a longitudinal, inner channel that stretches from an outer end of the piston rod 44 adjoining a fastening body such as an "eye", to an inner end of the piston rod. The multi-cylinder comprises, as the figures show, an "eye" at each opposite end for fastening to machinery.

It shall be mentioned that the designations "upper" and "lower" are only referring to the multi-cylinder as it is shown in the drawing and not to the actual working position. Furthermore, the expressions "upper" and "lower", refer to, when it concerns the definition of working chambers, the part of the cylinder which is above the piston and below the piston, respectively, and/or any limiting edge sections as shown in the figures. For example, the piston can be driven to the bottom of the first cylinder so that working chamber 1 comprises the main part of the cylinder, the expression "upper" part of the cylinder still refers to the part of the chamber that is above the piston. The upper, outer part of the first cylinder 40 can function as a piston 62 in the second cylinder 50. A multi-cylinder with four working chambers is shown in figure 3. Here, the upper, outer end of the first cylinder 40 can alternatively comprise an outwardly extending, circular edge section 52, which in a corresponding way is arranged to lie against the inner surface of the second cylinder 50 so that it forms a seal.

As sealing means in the multi-cylinder, normal sealants in the form of gaskets, such as piston rings, for example o- rings, or other sealing means that are suited for use in piston/cylinder systems can be used advantageously. The sealing means can be fitted around the piston 42, about the upper end of the first cylinder and possibly also in or at the lower end of the second cylinder. The piston rod 44 can move in the first cylinder 40 so that sealing means can also be arranged in a boring in the upper end of the first cylinder, through which the piston rod is movably arranged.

Figure 3 shows a principle diagram for a multi-cylinder with four working chambers that combines hydraulic oil and gas. Hydraulic oil can be supplied to/evacuated from working chamber 2 by way of the longitudinal inner channel 60, or in the hollow space, in the piston rod 44. Hydraulic oil is supplied to/withdrawn from working chamber 3 by way of the outlet/inlet openings 47 at the lower end of the first cylinder 40. The working chamber 1 can be filled with gas under pressure, where the gas can be in communication with an expansion tank, or accumulator, by way of the opening 48. The cylinder is thereby controlled as normal with hydraulic oil in the working chambers 2 and 3, while the gas that is supplied to the working chamber 1 contributes to the cylinder being given an extra power of expansion, i.e. that a "free" lift is provided with the help of the multi-cylinder without, for example, the engine power of the mechanical digger being affected. In this case, working chamber 4 can be controlled by hydraulic oil.

The multi-cylinder (shown in figure 3) can take up several working positions from the supply/evacuation of hydraulics and gas; an extended position where the working chambers 2 and 4 are in the main emptied of pressure medium, an intermediate position where pressure is exerted in all chambers and an approximately compressed position where working chambers 1 and 3 are mainly emptied of pressure medium.

Other working positions that the multi-cylinder can take up according to the supply/evacuation of hydraulic oil and gas is that oil is supplied to working chamber 4 so that gas is forced out of working chamber 1. This results in the extra expansion power no longer being available, and the multi-cylinder can be used as an ordinary cylinder, where the piston rod 44 becomes the visible piston rod.

The multi-cylinder can also be used as a gas cylinder only. Then the working chambers 1 and 3 can, for example, be filled with gas, while chamber 2 is controlled with hydraulic oil to remove gas from chamber 3 and correspondingly, chamber 4 can be filled with hydraulic oil to remove gas from chamber 1. Alternatively, all the working chambers can be filled with gas.

Figure 4 shows an alternative embodiment of a multi- cylinder, where a cylinder with four working chambers is shown, with a combined cylinder for hydraulics and gas. In this embodiment, the inner first cylinder 40, at its upper end, adjoins a piston 42, equipped with one or more through openings 64 towards the working chamber 4. Chambers 2 and 4 can be regulated with hydraulic oil, while working chambers 1 and 3 are regulated with gas, possibly hydraulics and/or gas, respectively. The multi-cylinder shown in figure 4 will normally be constructed with more gaskets than the arrangements shown in the figures 2-3. The object of the opening 64, or the openings, is that, due to the working chamber 4 and the through-flow between chambers 2 and 4 a larger pressure face is provided, whereby a greater downwardly directed pressure is obtained. The advantage with this is that the necessary force is obtained when the mechanical digger beam is forced down to lift up the undercarriage or the machine. Thereby, it is not necessary with a channel in the piston rod 44 for the supply of hydraulic oil/pressure medium to working chamber 2.

Figure 5 shows another alternative embodiment that comprises three working chambers. Working chamber 4 is omitted in this embodiment, as are the circular outwardly extending edge section of the inner cylinder and the circular inwardly extending edge section at the lower part of the second cylinder.

Working chamber 3 will normally be regulated with hydraulic oil by way of the opening 48 and working chamber 2 will normally be regulated with hydraulic oil by way of channel 60 in the piston rod 44, while working chamber 1 can contain gas under pressure. Working chamber 1 is regulated by supply/withdrawal of gas by way of the opening 46. Such a cylinder construction is simple and can be constructed with few extra gaskets. It will normally have a relatively small power effect directed downwards and will therefore be best suited for equipment where a such downwardly directed force is not necessary, such as, for example, a wheeled loader or the like.

Claims

C L I M S

1. Device for a mechanical digger (10), where the mechanical digger comprises a lower drive machinery (12) and an upper rotational part (14), where to the upper part (14) is connected a lifting beam comprising a rotational lifting arm (18) which is articulately connected to an intermediate arm (20) to which a digging/lifting tool is articulately fitted, and a number of cylinders arranged to drive the lifting beam, c h a r a c t e r i s e d i n that one or more of said cylinders for raising and lowering of the lifting beam comprise a multi-cylinder (24) for hydraulics and gas, where the multi-cylinder (24) comprises one or more working chambers (2,3) that are arranged to receive/evacuate hydraulic oil, for lifting and lowering of the lifting beam, respectively, and at least one working chamber (1) arranged to receive/evacuate gas, to provide a counter-force which corresponds approximately to the downwardly directed power vector of the lifting beam.

2. Device in accordance with claim 1, c h a r a c t e r i s e d i n that said at least one working chamber (1) for gas is connected to an accumulator or an expansion tank.

3. Device in accordance with claim 2, c h a r a c t e r i s e d i n that the multi-cylinder (24) comprises three working chambers, where two of the working chambers (2,3) are arranged to receive/evacuate hydraulic oil, and a working chamber (1) which is arranged to receive/evacuate gas.

4. Device in accordance with claim 2, c h a r a c t e r i s e d i n that the multi-cylinder (24) comprises four working chambers, where one or more working chambers (2,3) are arranged to receive/evacuate hydraulic oil, and one or more working chambers (1,3) that are arranged to receive/evacuate gas.

5. Device in accordance with one of the preceding claims, c h a r a c t e r i s e d i n that one or more multi-cylinders (24) are arranged between a forward section of the upper part (14) and an inner section of the lifting arm (18) .