The invention relates to a method in connection with an accumulator of a cable or the like, the accumulator being used to adjust the tension of the cable or the like during spooling, whereupon the cable or the like is made to pass around a movable wheel, preferably a movable wheel with a balancing spring, and the movable wheel provides the desired tension in the cable or the like. The invention further relates to an arrangement in connection with an accumulator of a cable or the like.

This kind of accumulators are known at present especially in the cable industry, where the accumulator is used as a device that adjusts the cable tension to the desired level for example during spooling.

Known accumulators operate in such a way that the accumulator comprises a movable wheel, which provides the cable with the desired force or tension. The force is produced in the cable either by the mass of the movable wheel or by a separate actuator, which acts on the movable wheel . The actuator may be for example a hydraulic or pneumatic cylinder, electric motor, solenoid or some other corresponding apparatus. In apparatuses utilizing the mass, tension can be adjusted simply by changing the position of the weight attached to the movable wheel .

The movable wheel may also comprise an associated balance system provided by means of a spring. The balancing spring is used since the mass of the movable wheel causes a certain tension in the cable with its gravity, and since the tension caused by this mass may be greater than the desired minimum tension of the

cable; it is thus necessary to reduce the mass of the movable wheel for example with a spring.

Previously known apparatuses have for example such a disadvantage, however, that the inertial masses of the movable wheel produce rather considerable additional tension peaks in the cable. This means that when the position of the movable wheel changes at a certain speed and acceleration, the total force which is caused by the inertial mass and which produces tension peaks in the cable also changes. Another drawback is that the spring force of the balancing spring changes as a function of the position of the movable wheel, so that the tension produced by the movable wheel in the cable varies together with the variation of the position of the movable wheel. Due to the above-described matters, it is difficult to maintain the tension exactly at the desired level with the previously known apparatuses.

The purpose of the invention is to provide a method and arrangement by means of which the prior art drawbacks can be eliminated. This is achieved with the invention. The method according to the invention is characterized by first measuring the acceleration and speed of the movable wheel, then determining the additional force resulting from the inertial mass of the movable wheel at the acceleration measured, and then adding the aforementioned additional force to the force applied by an actuator of the movable wheel on the movable wheel or subtracting the aforementioned additional force from the force applied by the actuator of the movable wheel on the movable wheel . The arrangement according to the invention is in turn characterized in that the arrangement comprises first means arranged to measure the acceleration and speed of the movable wheel, second means arranged to determine

the additional force resulting from the inertial mass of the movable wheel at the acceleration measured, and third means arranged to add the aforementioned additional force to the force applied by an actuator of the movable wheel on the movable wheel or to subtract the aforementioned additional force from the force applied by the actuator of the movable wheel on the movable wheel . An alternative embodiment of the method according to the invention is characterized by first measuring the position of the movable wheel, then determining the spring force dependent on the spring constant of the spring balancing the movable wheel and on the position of the movable wheel, and adding the aforementioned additional force to the force applied by an actuator of the movable wheel on the movable wheel or subtracting the aforementioned additional force from the force applied by the actuator of the movable wheel on the movable wheel . An alternative embodiment of the arrangement according to the invention is in turn characterized in that the arrangement comprises first means arranged to measure the position of the movable wheel, second means arranged to determine the spring force dependent on the spring constant of the spring balancing the movable wheel and on the position of the movable wheel, and third means arranged to add the aforementioned additional force to the force applied by an actuator of the movable wheel on the movable wheel or to subtract the aforementioned additional force from the force applied by the actuator of the movable wheel on the movable wheel.

The primary advantage of the invention is that the additional force caused by the inertial mass of the accumulator can be compensated for when the accumulator is in the accelerating state. Thus the tension caused by the accumulator in the cable or the like is also

constant regardless of the acceleration of the accumulator. Another advantage is that the variable force depending on the position and caused by the balancing spring of the accumulator can be compensated for. Therefore the tension produced by the accumulator in the cable or the like is constant regardless of the position of the accumulator and the balancing force of the spring. A further advantage of the invention is its simplicity with respect to the advantages it provides, which makes the invention inexpensive to implement.

The invention will be described below in greater detail by means of a preferred embodiment shown in the accompanying drawing, in which the only figure illustrates the characterizing features of the arrangement according to the invention.

Reference numeral 1 in the figure generally denotes an accumulator of a spooler. Reference numeral 2 denotes a movable wheel around which a cable or the like 3 is applied. The movable wheel 2 provides the cable or the like 3 with a desired tension. In the example of the figure, the force producing the tension T in the cable or the like is provided with an actuator 4, which may be for example a pneumatic cylinder. The actuator 4 is arranged in the example of the figure to act on the movable wheel 2 in such a way that the wheel moves according to the arrows marked in the figure. The level of the tension produced by the actuator 4 in the cable can be adjusted by regulating the actuator by means of a valve element 5. The force producing the tension can also be provided by means of the mass of the movable wheel 2. Reference numeral 6 denotes a spring balancing the load of the movable wheel.

The structure and the operation of the accumulator constitute fully conventional technology to a person skilled in the art, wherefore they will not be

described in greater detail in this connection. It is only stated that the cable or the like 3 is guided onto the movable wheel 2 by means of suitably positioned guide wheels, as shown in the figure. According to an essential feature of the invention, the additional force, which may result from the inertial forces of the movable wheel 2 or from the position of the movable wheel 2 and the spring constant of the spring 6, is measured. The aforementioned additional force is taken into account when determining the force that is provided in the cable or the like 3 by means of the actuator 4.

The aforementioned essential feature can be implemented by first measuring the acceleration and speed of the movable wheel 2 and by then determining the additional force resulting from the inertial mass of the movable wheel 2 at the acceleration measured. The additional force is added to the force that the actuator 4 of the movable wheel 2 applies on the movable wheel or it is subtracted from the force the actuator 4 of the movable wheel 2 applies thereon, depending on whether the additional force is positive or negative in the situation.

The essential feature of the invention can also be implemented by first measuring the position of the movable wheel 2, then determining the spring force dependent on the spring constant of the spring 6 balancing the movable wheel 2 and on the position of the movable wheel 2. The aforementioned additional force is added to the force that the actuator 4 of the movable wheel 2 applies on the movable wheel or it is subtracted from the force the actuator 4 of the movable wheel 2 applies on the movable wheel, depending on whether the additional force is positive or negative in the situation.

It is clear that when the actuator 4 is compensated, it is naturally possible to use both the additional force based on taking into account the inertial forces and the additional force based on the spring constant of the balancing spring and on the position of the movable wheel, if the accumulator has such a construction that it comprises for example a balancing spring for the movable wheel, among others . The acceleration and speed of the movable wheel 2 can be measured by means of first means 7. The first means 7 can also measure the position of the movable wheel 2. The arrangement also comprises second means 8 that are arranged to determine the additional force resulting from the inertial mass of the movable wheel 2 at the acceleration measured above. The second means 8 can also determine the additional force, i.e. spring force, dependent on the spring constant of the spring 6 balancing the movable wheel 2 and on the position of the movable wheel 2. The arrangement also comprises third means 9 that are arranged either to add the aforementioned additional force to the force applied by the actuator 4 of the movable wheel 2 on the movable wheel or to subtract it from the force of the actuator 4, as described above. The means 8 and 9 can be positioned in a control unit 10, as in the example of the figure. The means 8 and 9 can be implemented for example by means of suitable processors and programming.

The invention provides a uniform tension of exactly the desired level within the entire operating range of the accumulator.

The above-described embodiment is not intended to limit the invention in any way, but the invention can be modified freely within the scope of the claims. It is thus clear that the arrangement according to the invention or the details thereof do not necessarily have

to correspond exactly to those shown in the figure, but other kinds of arrangements are also possible. Instead of a pneumatic cylinder, the actuator may be for example a hydraulic cylinder, an electric actuator etc. The accumulator may ^' consist of a lever construction as in the example of the figure, or of a linear accumulator wherein the movable wheel moves rectilinearly in the vertical direction. The invention is not restricted to cables, either, but it can be used for example in connection with ropes, cable wires, wires and other similar products. Even though the invention is described above by means of an embodiment related to a cable spooler, it should be noted that the invention is not restricted in any way to spoolers, but it can also be applied in other connections.