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 rotatory part, where a digging unit is connected to the upper part, comprising a vertical rotatory lifting arm that is articulately connected to a digging arm to which a digging/lifting tool is articulately fitted, and pressure cylinders arranged to drive the digging unit.
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 lifting arm 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 consequently 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 digging unit of the mechanical digger, i.e. the lifting arm, as weightless as possible. To achieve this, an auxiliary cylinder with a lifting function, or a spring system with a screw/pulling force, is fitted to the mechanical digger' s lifting arm. The advantages with this are, among other things, that energy (fuel) is saved. For example, hydraulic pressure cylinders can be used, which thereby do not have to lift the weight of the lifting arm. During scooping out and unloading, the lifting arm is, as mentioned, lifted about twice a minute.
The larger the machine is, the larger the lifting arm 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 a first end of an auxiliary device is arranged to the upper part so that it can be moved horizontally, and that another end of the auxiliary device is arranged to the lifting arm, where the auxiliary device is providing an adjustable counter force that approximately corresponds to the downwardly directed force vector of the digging unit. Preferred embodiments of the invention are characterised in that the auxiliary device comprises a spring or gas cylinder, arranged to provide a counterweight to the digging unit. Furthermore, the auxiliary device can be fitted, angle-adjustably adjacent to a lower, forward section of the upper part, where the first end of the auxiliary device preferably can be connected to a dis- placeable slide which is fitted in, or adjacent to, the lower, forward section, and where the slide extends horizontally out from the mentioned lower section.
The slide can be arranged to be displaced in an approximately horizontal plane by the aid of drive means, where the drive means can comprise, for example, a hydraulic cylinder. An alternative embodiment of the invention relates to a device for lifting machinery/digging machinery, fitted to which is a rotatory lifting arm which is articulately connected to an intermediate arm to which a shovel/lifting equipment is fitted, and pressure cylinders are arranged to drive the lifting arm, the intermediate arm and the shovel/lifting equipment. Whereby an auxiliary device is arranged between the lifting arm and the lifting machinery/digging machinery, and where the auxiliary device is arranged to provide a counter force that corresponds approximately to the downwardly directed force vector of the digging unit.
The invention shall now be described in more detail by means of the enclosed figures, in which:
Figure 1 shows a mechanical digger comprising a device according to the present invention.
Figure 2 shows the equivalent of figure 1 with the digging unit in a different position. Figure 3 shows an auxiliary device according to the present 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 are not dependent on the position of the mechanical digger itself on the terrain.
Connected to the upper part 14 is a digging unit which comprises a lifting arm 18 that is vertically rotary connected to the upper part 14, the lifting arm can also possibly be able to rotate 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 move a shovel 22, or other equipment, to a desired posi- tion by the aid of fitted pressure cylinders, such as a first pressure cylinder 24 and a second pressure cylinder 26 and a third pressure cylinder 28.
The pressure cylinders 26 and 28 are fitted in a way known to an expert, and will therefore not be further described. The first pressure cylinder 24 is preferably fitted as shown in figure 1, i.e. 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. However, the first pressure cylinder 24 can also be fitted in a conventional way, i.e. between an inner point on the lifting arm and a forward point on the upper part. Of
course, it shall be mentioned that a number of cylinders can be used.
To lift and move the digging unit, i.e. the lifting arm, the digging arm and the shovel, pressure cylinders are used, as mentioned. This leads to the mechanical digger using a lot of energy in the form of fuel. One of the objects of the present invention is, among other things, to reduce the energy consumption. To achieve this, an auxiliary device 30 is fitted between the upper part 14, preferably at the lower, forward section 14a of the upper part, and an inner section 18a on the lifting arm. With inner and outer section is here meant the part of the lifting arm that turns up and down, respectively, viewed in the normal plane. The aim of the auxiliary device 30 is to make the digging unit, i.e. lifting arm and digging arm, as "weightless" as possible. The fuel consumption is reduced, in that the pressure cylinders, which are normally driven hydraulically, do not have to lift the weight of the arm. During scooping out and unloading, the arm is normally lifted about twice a minute. So that the bigger the machine is, the larger the lifting arm that shall be lifted, and the more fuel to be saved.
The auxiliary device 30 will preferably be made up of an auxiliary cylinder in the form of a gas or spring cylinder and shall function as a counterweight to the digging unit. The auxiliary device 30 is fitted, preferably angle-adjustably, adjacent to the lower, forward section 14a of the upper part 14, i.e. the first end of the auxiliary device is connected to a displaceable slide 32 that extends out from the lower, forward section 14a of the upper part 14. The slide 32 will be arranged so that is can be displaced in an approximately horizontal plane with the aid of drive means 34 that can be steered from, for example, the driver's cab 16. The pressure force that is exerted from the auxiliary cylinder can be regulated with the aid of the slide. In this way one can correct the weight of the arm in relation to the task that is to be carried out. With a correct
setting on the auxiliary cylinder, one can get a lifting cycle almost without the use of hydraulic power on the arm movement .
The system also gives the machine an extra strong arm lift, as the power of the machine is not used to lift the arm itself.
The slide (32) can preferably be driven by a hydraulic cylinder (34) that shall be controlled from the driver's cab. From here, the pressure on the lifting cylinder is read by means of, for example, a manometer. The slide (32) controls the momentum of the auxiliary device/cylinder, and is adjusted manually by the driver to change the "weight" of the arm, according to which work operation is to be carried out. Alternatively, the slide can be computer controlled.
Furthermore, the lifting cylinder (34) can be fitted behind the arm to lessen the strain on the bolt with which the arm is hinged onto the machine.
The auxiliary device can in an alternative embodiment comprise a spring or a spring system. The spring can be arranged correspondingly as is shown in the figures, or it, or a number of springs, can be arranged on the opposite side of the lifting arm 18. That means that the first end of the auxiliary device (30) can be fitted, possibly to be able to move horizontally, to the upper part (14), and the other end of the device (30) can be fitted to the outer side of the lifting arm (18), where the auxiliary device (30) is correspondingly arranged to provide a counter force which corresponds approximately to the downward directed force vector of the digging unit.