FI122061B - Arrangement in connection with forestry machine power source - Google Patents

Description

Arrangement in connection with forestry machine power source

Background of the Invention

The present invention relates to an arrangement according to the preamble of claim 1 for implementing a power transmission of a forest machine.

Several different types of harvesting machines are known to perform mechanical harvesting, such as forwarders and harvesters, i.e. harvesters, to implement the so-called cut-off method. On the other hand, to implement the so-called whole-wood method, a number of different harvesting machines are known, such as a feller, a skimmer and, for example, a peeling machine. These machines will be referred to collectively as forestry machinery.

In general, the forest machine comprises a ground-moving platform or a ground machine, which may be wheeled or tracked, for example. In addition, a forest machine, particularly a machine for cutting material, almost invariably comprises some form of boom or manipulation platform for supporting and moving an actual woodworking device or tool, such as a harvester head or, for example, a grapple, to the respective tree body. These devices, which are adapted to be supported at the end of the boom, are in turn largely responsible for the actual operations on the tree trunk being processed. Typically, the harvester head performs function-20 and includes, for example, felling sawing, logging and pruning functions, and cutting the trunk to be processed into desired lengths.

The power transmission of these mobile implements, which in this context is particularly understood to be forestry machinery, has been used in technology as a result of a variety of power transmission methods. In the case of forest machines, such a transmission of the te-25 can be considered to be divided into two main categories on the basis of its intended use, on the one hand, the movement of the forest machine itself, the so-called ^ propulsion, i.e.

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but only for traction and on the other hand for transmission of implements such as loaders, cranes, harvester heads and the like comprised in a forestry machine.

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£ 30 The most commonly used (o) power source for this type of forestry machine is a diesel engine, the power of which is transmitted o to the various functions mentioned above, almost invariably hydraulically. For this purpose, the primary power source uses the power transmission equipment fitted to the forestry machine. This consists, inter alia, of one or more hydraulic pumps which convert the mechanical shaft power provided by the power source into hydraulic power, i.e. volume flow and pressure 2, in the hydraulic system associated with the hydraulic pumps. This hydraulic power is used to perform woodworking tasks or other functions at a desired location in various parts of the forest machine through hydraulic actuators such as hydraulic cylinders and motors. These hydraulic pumps and -5 systems are reserved for the desired number of different parts of the forestry machine. A typical solution is that at least one propulsion system has its own system and at least one system is devoted to the power transmission of the implements.

In some cases, the power provided by the primary power source may also be mechanically transferred, for example, to the drive train. It is also known to utilize the telo hoa to a lesser extent for use in a forest machine electrical system such as lights and control systems. The use of mechanical transmission in combination with hydraulic, hydrostatic or hydrodynamic transmission in the series is also common and well-founded, thus reaping the benefits of both types of transmission.

15 It is typical for a forestry machine that the load generated by its various functions on the primary power source using the entire system varies considerably. These fluctuations can even be almost step-by-step, with forest machine operations alternating rapidly during logging work cycles. For example, some of the functions of the harvester head are very low power consuming but nonetheless necessary for the job. Such low-power functions can be thought of as crimping knives and feeders against the wood to be treated, as well as moving them to their open position. On the other hand, the large power users of the harvester head are, in particular, the feeding of wood and its cutting saw. The functions of the boom 25 are typically lifting, folding, extending and swinging, of which lifting and swinging in particular use significant power. In addition, these functions often have to be combined with practical work at the same time.

ώ The load-sensing LS (Load Sensing) system, which is commonly used in the forestry machine, poses its own problems. This system aims to save energy, but is not advantageous in situations where the hydraulic system pressure levels of the functions used simultaneously vary considerably. This problem can often be detected, for example, by simultaneous operation of the boom lifting and turning section. Thus, lifting the boom requires significantly high pressure and maybe 35 only moderate volume flow. The simultaneous rotation of the boom may in turn require a high volume flow and perhaps only moderate or 3 slight pressures. It follows that the hydraulic system using the boom will have to produce the combined volume flow and the highest effective pressure required by the functions, whereby the power required from the primary power source is essentially the product of these two values. More specifically, the power required should be supplemented by the effect of the pressure difference typical of the LS system. For the system to function as intended, it requires a differential pressure of about 25 bar between the maximum load pressure and the system pressure.

When looking at a forest machine, the power requirement 10 for each of its functions is relatively easy to calculate due to hydraulic power transfer, the power requirement being the product of the volume flow per function and the maximum system pressure during operation.

When comparing a forestry machine to heavy or lighter vehicles used in road traffic, for example, or to many other work machines, there is an exceptionally large variation in the power requirement of a forestry machine. As a result, special care has to be taken in the selection of the diesel engine typically used as the primary source of power in forest machines. This has ensured that the selected and rated engine is responsive enough to these fast load variations, while still complying with the current emissions regulations.

The largest load variations consist of sawing and feeding operations. They are also the functions that place the greatest pressure on the hydraulic system and the power source. The power requirement for both sawing and feeding is very instantaneous, but at the same time their power requirement is very high. The instantaneous nature of these operations is illustrated by the fact that the duration of the sawing operation is essentially less than one second, and that of the feeding operation is not more than a few seconds. Since there are very few other functions performed by the forest machine during felling, ώ the power requirement for the power source between these functions is reduced to substantially zero. Such instantaneous power demand peaks place particularly high ^ 30 demands on the power management of a forestry machine. On the other hand, in the case of a forwarder, the power source is particularly loaded by the boom lifting function and the traction transmission.

o Typically, for example, the primary power source of the harvester o needs to be dimensioned so that it can reasonably handle momentary

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35 heavy loads. These include, in particular, the load caused by starting the feed or pruning or, for example, by cutting the cut. Another typical workload that significantly loads 4 power units is to run multiple functions of the loader or crane, especially at the same time and at high speeds.

However, such a principle of supplying the primary power source mi-5, as mentioned above, results in a significant oversize, especially in the case of a forestry machine, in relation to the average power requirement. This, in turn, means that for a significant part of its operating time, the power source operates at a remarkably low power output, which means both reduced efficiency and fuel economy.

10 Thus, it is not at all uncommon for an harvester, in particular, to have an average power requirement of 40 kW per power source when its current maximum power requirements are well above 100 kW. In some situations, the speed of operations may need to be limited because the primary power source would not be overloaded and its RPM would adversely begin to sink. Indeed, this type of loss of RPM has been found to be particularly detrimental to both the productivity of the harvesting work done and the fuel economy of the forest machine. In addition, RPM has also been found to cause a tendency to increased exhaust emissions. On the other hand, the active control and prevention of emissions from a modern diesel engine, such as 20 for instance smoke, makes it difficult to correct said decay. In order to increase the RPM of a heavily loaded power source, large volumes of fuel injection are required in practice. This, in turn, is a measure which, of course, is likely to increase emissions from the power source. In other words, the current stringent emission regulations no longer allow for such a high level of fuel injection in this type of situation where the engine RPM and hence, for example, the charge air pressure have begun to decline than the prior art and less stringent emission regulations.

4 · In the prior art, there are some solutions for controlling the power of a forest machine by adjusting control parameters as such to adjust the characteristics of a tunneled power source, such as power production readiness and capability, to adjust to the level set by the particular work step. A prime example of such a method for controlling a forest machine engine is provided in FI111183. As such, however, the C 1-135 technique disclosed in this publication does not solve the present problem of dimensioning a forest machine power source, but a primary power source, such as a diesel engine, 5 must still be sized to meet the maximum instantaneous load, that is, unnecessarily high. In addition, the actual power requirement for the trunk required by this publication is very difficult to evaluate in practical wood harvesting work, where the power requirement for a given trunk treatment 5 is influenced by many other factors than, for example, the diameter of the trunk.

Brief Description of the Invention

It has therefore been an object of the present invention to provide an arrangement for a forestry machine power source that provides a solution to the above-mentioned problems of the prior art drawbacks that allow substantially better energy economy and significantly reduced primary power source technology. Further, with the present solution, the arrangement can be directed to operate as economically as possible, yet with sufficient performance in the particular working situation specific to the forestry machine. The solution enables the primary power source of the forestry machine to be arranged to operate at the lowest possible operating point.

This object is achieved in that the arrangement with the power source of the forestry machine according to the present invention has the features defined in the claims. In particular, the present problems can be solved by combining the features in a manner similar to that of claim 1.

Preferred embodiments of the invention are the subject-matter of the dependent claims.

The invention is based on the idea that, unlike prior art, a forest machine is provided with a power supply arrangement consisting of both a primary power source known per se, such as a diesel engine, and an electrical machine, such as a combined diesel engine,

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£ 30 for torque motor and generator.

cd The electrical energy generated by the primary power source and the electrical machine can be stored and discharged to be used again to produce a pressure medium-driven power advantageously used by the forestry machine, for example via a hydraulic pump. Particularly preferably, the electric energy can be stored for a longer period of time at a desired location in an accumulator located in a work machine or in another known electrical energy storage device, or a combination thereof, from which it can be utilized when required. Such may be the case, for example, with the so-called ultra capacitor, which is capable of short-term and rapid charge and discharge of large amounts of electrical energy.

Said auxiliary torque motor and generator can be advantageously integrated in a manner known per se, for example in place of, or in connection with, a diesel engine flywheel, however, if necessary, said electric machine can serve as an actual primary power source, e.g. As is well known, this auxiliary torque motor can also replace the conventional starter motor and the charge generator required by conventional electrical systems.

On the other hand, some of the functions of the forestry machine may be those which, in the case of the arrangement according to the invention, are worth performing directly by electrical means without hydraulic actuators. Examples of such operations include, for example, boom extension and harvester head rotation.

The invention provides considerable advantages. Thus, unlike the prior art, the primary power source of a forestry machine can be dimensioned substantially in accordance with the average power requirement and can be thought of as always operating at the highest efficiency point. In other words, it is possible to implement a power supply arrangement for a forest machine, wherein, for example, a diesel fueled internal combustion engine operates continuously at substantially constant power consumption, generating electrical energy for storage in said storage means by means of a generator. When the power required by the power supply arrangement exceeds this average power consumption or the power output dictated by the standard power of said diesel engine, an additional torque engine is utilized. This additional torque motor still lowers the amount of electrical energy stored in the storage means for operating the primary power source devices, such as hydraulic pumps. The satisfaction of the instantaneous power demand peak achieved by the invention enables the primary power source to be dimensioned considerably.

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£ smaller than the barrier. This is a significant advantage, for example, in terms of the overall fuel economy of the forest machine and the weight of the forest machine. Of course, the smaller power source also has the potential to reduce the emission level of the forestry machine and to reduce the noise level and vibration generated by the power source, with the resulting structural advantages.

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Accordingly, the invention allows, especially during momentary high power demands of woodworking equipment on a forest machine, to direct a substantially greater amount of power to a pressure medium system than the calculated maximum power of a primary power source alone, without interfering with this. This is possible because the required additional power can be taken in the form of electrical energy stored in different charging means. If necessary, such electrical energy can be further converted, for example, by means of a hydraulic pump driven by an electric motor into a hydraulic power which is directed to a woodworking device.

10 In the case described, the forest machine manufacturer has the opportunity to optimize the primary power source therein for its purpose. Thus, such a primary power source can operate at the best possible efficiency, for example, at the best speed and load. This, in turn, contributes to the aforementioned 15 low fuel consumption, which is of increasing importance, especially for the forest machine owner and operator, as fuel prices continue to rise. When the load on the primary power source is as even and predictable as possible, the ever-tightening emission regulations are also easier to fulfill.

Since the solution according to the invention allows at least some of the power required by the hydraulic functions to be shifted electrically closer to the point of use in the construction of the machine, it also largely avoids cumbersome pressure medium lines. In addition to structural problems, these always result in flow losses, which may impair the efficiency of the power transmission.

On the other hand, one advantage of the invention is also achieved by the possibility of locating pumps associated with a pressurized medium system of a forestry machine, o control valves and controls in one or more compact arrangements at a distance cd from the primary power source. Such a location can be

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for example in connection with a pressure medium container. This placement has significant effects on, for example, reducing the noise level in the cab of a forwarder, because now, in some cases, noisy pumps and valves can be positioned, for example, on the stand of a loader on a forestry machine or even inside a pressurized medium tank. Thus, the various components associated with this pressure medium system are

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35 even placed on a different part of the forest machine than its cab and primary power source.

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The invention further facilitates the design of a forest machine by allowing for a freer placement of components within the structure of the forest machine. In the known solution, for example, one or more pressure medium pressure pumps have been placed in the vicinity of the primary power source which have pressurized the pressure medium for use in various functions of the forest machine. This has resulted in the formation of a large and bulky unit in the vicinity of the primary power source, which has often been difficult to locate on the forest machine body. Thanks to the solution of the invention, this structure can now be decentralized. Because the pri-10's own power source is also feasible at a smaller size, it can be reconsidered for placement in a forest machine design.

The high power electric generator provided by the present solution is also useful in many other ways in the case of a forestry machine, as it can replace the prior art separate starter motor and 15 generator generator. In particular, in the case of modern forest machines, the load generator is under heavy load. Again, the solution of the present invention provides an advantageous structure compared to current belt-driven charge generators.

Other advantages of the invention are set forth below, when specific embodiments of the invention have been described in more detail.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, some preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawing, in which Figure 1 is a schematic side view of a forest machine, Figure 2 is a schematic diagram of the present arrangement for power transfer and tool control; 2 through the arrangement of power transfer and control of the implement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Q_30 In the context of the present method and arrangement of a power source for a forest machine, some preferred embodiments are described below with reference to the above figures. In this case, the arrangement comprises the components designated by reference numerals in Figures c3, which correspond to those used in this specification by reference numeral.

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Fig. 1 shows a preferred construction of a forestry machine 1, in this case comprising a forwarder with articulated advantages 2 with a rear frame 2 and 3. The front frame has a forestry machine cab 4 which also controls the primary power source 5 for driving the forestry 5 and its attachments. and the power to steer. Some of these implements are represented by a loader 6 and a grab 7 attached to it, which are distinguished from Fig. 1.

In the arrangements of Figures 2 and 2, the primary power source 5 of the forest machine 1 is used not only to produce pressure-medium-powered power 10 but also to generate electrical energy. The pressure medium-mediated power thus obtained can be used both for controlling the forestry machine and for controlling the working or other equipment therein. In turn, at least a portion of the generated electrical energy is arranged to be stored for shorter or longer periods in one or more electricity storage means 8, represented by, for example, conventional batteries 9, supercapacitors 10 or other means for storing electricity 11. , which controls the loading and unloading of storage devices. The components of the arrangement, as well as the electrical and pressure medium lines, are shown schematically only in diagrammatic form to illustrate the structure and function of the arrangement.

To produce electrical energy, a primary power source 5, which is part of the power supply arrangement of the forest machine 1 and is known per se, is provided with an electrical machine 13 comprising, for example, an auxiliary torque motor and a generator. According to Figure 2, these can advantageously be integrated in a manner known per se, for example, in place of, or in connection with, a flywheel of a primary diesel diesel engine. The electrical machine is also o adaptable in the immediate vicinity of the primary power source.

Thus, the primary purpose of the means 9-11 for storing electricity is, where necessary, to dismantle and conduct at least part of the electrical energy 30 from the storage means for use again advantageously in the forestry machine 1.

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£ for producing and transmitting this pressure medium mediated power to a 05 forest machine pressure medium system, for example, so that said electric machine 13 acts as an auxiliary primary power source 5, e.g. In this case, the maximum power produced by the additional torque motor in the electric machine is 30-120%, preferably at least 70% of the power produced by the primary power source.

From the storage means 8, electrical energy may also be directed, if necessary, to one or more of the conversion means 15 of Figure 3 to utilize this stored electrical energy to provide pressure-media-mediated power in one or more locations distributed to the forest machine. The arrangement thus provides some kind of power generating units operating in parallel with the primary power source 5 of the forestry machine 1.

On the other hand, the electrical energy discharged from the storage means 8 can thus be advantageously used to satisfy the momentarily increased power requirement of the forestry machine 1. On the other hand, the power produced by the primary power source 5 can be converted into electrical energy and directly used to control the forestry machine and its implements. This can be seen in Figure 2, in which the rotational movement of the grab and the control of the boom extension are shown to be carried out electrically via the electric motors 16 fitted thereto. Thus, the forestry machine can even be thought to operate for a limited time with the primary power source inoperable.

Thus, the increased need for power-20 of the forest machine 1 according to the present solution can be satisfied, either directly by the electrical energy discharged from the storage means 8, or alternatively this electrical energy can be converted and distributed by . It is of course possible to convert the electric energy already used to control the forest machine into hydraulic power by adapting the conversion means 15, for example, in connection with the wheels 17 of the forest machine o.

cd The present arrangement has a pressure medium-mediated power provided in the transducer 15 of the embodiment of FIG. or use of the grab o 7. It is, of course, also possible to control such devices with pressure medium-mediated power provided only partially in the conversion means, or

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35 actuator for a single movement of the woodworking machine in the forestry machine.

Preferably, the conversion means 15 in the arrangement comprises a pump unit 18 for pressurizing the pressure medium in the forest machine pressure medium system and an electric motor 19 driving it, such as a permanent magnet motor or a short circuit motor. A special control unit 20 is arranged to control the operation of the electric motor. If the pump unit is of variable volume type, the flow rate produced by it can be affected by changing both the speed of rotation and the volume of rotation. When the conversion medium used to achieve the pressure medium mediated power comprises a pump unit which is a fixed volume, its volume flow control is preferably arranged to be adjusted by controlling the rotational speed of the electric motor adapted to drive the pump unit. The speed of such an electric motor is adapted to be controlled, for example, by a frequency converter connected to the system. The solution enables the use of low-cost gear pumps and other low-volume pumps of low-cost type in the conversion medium.

When the conversion means 15 used to provide hydraulic power comprises a pump unit 18 which is adjustable in volume, an electric motor 19 can be adapted to drive the pump unit, which preferably rotates at a purpose optimized speed.

One particular advantage achieved by the arrangement is the possibility of locating the conversion medium 15 used to provide the pressure medium-mediated power in the layout of the forest machine 1 almost anywhere. Thus, at least one of the conversion means is adaptable to the pressure medium container in the forest machine. The conversion medium can even be fitted inside such a pressure medium container, whereby the noise it produces can be effectively attenuated. It is also possible to choose a solution in which the conversion means with the electric motor 19 therein is fitted to the rear frame 3 of the forestry machine.

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£ Such separation of the conversion means from the primary power source 5 simplifies the layout design of the forestry machine, especially the forwarder, and allows for a better weight distribution of the forestry machine.

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In order to avoid long pressure medium lines, the conversion means 15 01 with its pump units 18 and electric motors 19 can be placed up to a base 21 in a loader 6 mounted on the rear frame 3.

In Figures 2 and 3, one or more storage means 8 are ™ 35 preferably disposed within or in contact with the rear frame 3 of the forestry machine 1.

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In a particular embodiment of the present arrangement according to Fig. 3, there is also provided an arrangement in which the conversion medium 15 used to achieve the pressure medium mediated power comprises a pump unit consisting of a pump motor 180 rotating in both directions.

An electric motor 19 using such a pump motor can also be adapted to operate to recover energy, thereby forming a generator for supplying electric energy to the storage means 8. Thus, for example, when calculating the hydraulically supported load in the loader 6, the back flow of the pressure medium can be utilized so that the energy contained therein can be converted into electrical energy. Of course, the electrical energy provided in this manner can also be directed to the electrical actuators 22 in the system for use or storage in an electrical storage medium.

The arrangement of the power transmission of the forest machine 1 according to Figures 2 and 3 works as follows. The primary power source 5 of the forestry machine produces the power needed to move and control the 15 forestry machines and their implements, whereupon operating instructions are obtained from the operator of the forestry machine through the control means 23. At least some of the mechanical power generated by the primary power source, controlled by the engine control unit (ECU) 24, is converted by electrical machine 13 into electrical energy, which is at least partially stored in one or more electrical storage means 8 in the forest machine. Such storage means allow the electrical energy stored therein to be discharged in a very short period of time, if necessary, in the event of a sudden increase in the power requirement of the forest machine. Part of the mechanical power produced by the primary power source 25 is in turn converted by the hydraulic pump 14 into a volume and pressure displacement of the hydraulic system. This pressure medium flow thus results in hydraulic power as shown in Figure 2

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^ for actuators for different implements 25.

^ As the power requirement of the forest machine 1 increases and exceeds the power output capacity of the primary power source 5, or any pre-set activation threshold,

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At least some of the electrical energy from the storage means 8 is recycled back to the cd electric machine 13 or alternatively, or additionally, to one or more of the converting means 15 of Fig. 3. The electrical energy is now utilized by the pressurized medium to achieve. This pressure medium-mediated power is directed to one or more implements 13 on different sides of the forestry machine. In the implement, pressure medium-mediated power is used to perform or enhance the efficiency of the fluid-medium function. Thus, for example, in a forestry machine, the wood-handling device is controlled entirely or at least partially by means of pressure medium. It is also possible with the medium power of the Pai-5 to control only a single movement of the woodworking machine in the forest machine. The solution thus achieves a high efficiency because such a pressure medium-mediated system can be optimized for each function on a function-by-function basis.

The electric machine 13 as shown and the auxiliary torque motor 10 therein are preferably designed to operate so that the auxiliary torque motor 10 is activated when a certain predetermined load level of the primary power source 5 is exceeded while the forest machine 1 is operating.

In another embodiment of the present power transmission, said electric machine 13, and in particular the auxiliary torque motor 15, is activated when one or more predetermined functions of the forest machine 1 are activated. Specifically, such a function comprises starting the feeding and / or pruning of wood at the harvester head during operation, alternatively, the function may comprise cutting the tree. These functions are often such that power output from the primary power source alone is not sufficient. On the other hand, in the case of a chassis-20 tractor, the auxiliary torque motor can be thought to be activated when the transaxle is engaged.

In addition to harvester head functions, such a function may comprise one or more boom movement control functions.

On the other hand, modern power units 5, or engine control units (ECUs) 24 adapted to manage them, themselves know how much torque and speed (at which power is supplied) is drawn from the crankshaft end of the power supply at each moment. Thus, it is also possible to activate the auxiliary torque motor by some calculation algorithm based on this power.

When at least one such electrical energy conversion means 15

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£ is an organized energy recovery, the fuel economy σ> of the forest machine 1 can be significantly improved. One way to achieve such an energy recovery is that the above-mentioned conversion means is structured to allow 1?.

Use also for converting the energy contained in the pressure medium and feeding it back into the electrical system for use by actuators or for storing it in an electrical storage medium 8.

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It will be obvious to a person skilled in the art that as technology advances, the basic idea of the arrangement described above can be implemented in many different ways. The disclosed solution and its embodiments are thus not limited to the examples described above, but may vary within the scope of the claims. For example, it is evident that generator, electric motor, and electrical energy storage components involve various solutions not specifically described herein.

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Claims (7)

An arrangement in connection with a power source of a forestry machine (1), comprising at least one primary power source (5) and a primary power control device (23), the power provided by the power source being arranged to be transmitted by transmission means, preferably a pressurized fluid system therein a single electrical machine (13) adapted to use substantially the same transmission means, the electrical machine being adapted to function as both a generator and a motor, as the case may be, at least one electricity storage means (8) for storing a portion of the generated electrical energy; for providing pressure medium-mediated power in one or more of the multiple locations distributed to the forest machine, characterized in that the conversion means (15) is arranged on the forest machine (1) separately from the primary from the source of suction (5). Arrangement according to Claim 1, characterized in that at least one of the conversion means (15) is adapted to be connected to a pressure medium container in a forestry machine. Arrangement according to Claim 2, characterized in that the conversion means (15) is arranged inside the pressure medium container. Arrangement according to Claim 1, characterized in that the conversion means (15) with the electric motor (19) therein is arranged on the rear frame (3) of the forestry machine (1). C \ J Arrangement according to Claim 4, characterized in that the conversion means (15) with the pump units (18) and the electric motor (19) therein are arranged on the stand 30 of the loader (6) mounted on the rear frame (3). (21). No, Arrangement according to one of the preceding claims, characterized in that one or more electricity storage means (8) are arranged in connection with the rear frame (3) of the forestry machine (1). o An arrangement according to claim 6, characterized in that one or more electricity storage means (8) are arranged inside the rear frame (3) of the forestry machine (1).