MXPA99003585A - Dynamic and weight balance device for machines with rotors, in particular for industrial ventilating fans - Google Patents

Abstract

The invention concerns a dynamic and weight balance device for machines with rotors, comprising at least one rotor (4) borne by a revolving shaft (5), at least one weight balancing unit (20, 21) borne by said shaft, and at least a system for correcting and controlling the state of unbalance of the rotor (4), said system being capable of operating permanently on the balancing unit(s) (20, 21) when the rotor (4) is rotating. The invention is characterised in that:the weight balancing unit (20, 21) is located at an axial distance from the rotor and comprises at least two balance weights mounted movable independently of each other by the action of driving means controlled by the controlling and correcting system, said weights moving along paths forming a closed circuit about the revolving shaft (5). The invention is applicable to industrial ventilating fans.

Description

DYNAMIC AND PONDERAL EQUILIBRIUM DEVICE FOR MACHINES WITH ROTOR, PARTICULARLY FOR INDUSTRIAL FANS TECHNICAL FIELD The present invention relates to the general technical field of the dynamic and weight balancing devices for machines with rotor, in particular for turbo or industrial fans. The present invention deals with a dynamic and weight balancing device for machines with roo-r, in particular for industrial fans, which have at least one rotor supported by a rotating shaft, at least one unit of weight balance carried by said shaft and located at an axial distance from the rotor to balance, and at least one control and correction system for the imbalance state of the rotor, said system being able to act permanently on the balancing unit (s) when the rotor is rotating to control and correcting the balance of the rotor, the weight balance unit comprising at least two equilibrium masses mounted displaceable under the action of drag elements commanded by the control and correction system. The present invention also relates to an industrial fan equipped with a dynamic and weight balancing device according to the invention, and more generally to turbomachines such as steam turbines, compressors, whatever the fluid involved in the operation of the turbomachine , it being understood that the balancing device according to the invention is found more particularly, but not exclusively, its application in turbomachinery where the required balance capacity is important and of the order substantially of at least 100 000 g.mm, and of preference between 100 000 g.mm and 5 000 000 g.mm. PREVIOUS TECHNIQUE One of the main problems of high capacity turbomachinery, such as those described above, concerns the vibrations susceptible of being generated by these machines, in particular at the level of the sojinetes. In most cases / the origin of these vibrations comes from the imbalance of the rotor. In the case of industrial fans where the ventilation capacities are high, for example of the order of 100 to 10 000 kW, the normal conditions of their use necessarily imply the progressive or sudden appearance of a state of imbalance of the rotor. Indeed, these devices are intended to ensure ventilation in industrial sectors as varied as the nuclear industry, the chemical industry, the steel industry, the cement industry, or also thermal power plants. Consequently, they are commonly exposed to the risks of deposits of particles or of materials ventilated on or by the blades of the fan, by the progressive wear of the blades due to the different effects of corrosion coming from the fluids or gas transported by the fan , or also by the deformations coming from sudden variations of temperature. The deposit of materials (plugging) on the blades of the fan is effected, on the other hand, generally progressively and non-uniformly on the blades of the fan, which causes a first imbalance effect of the rotor. In some applications, and for example, in cement factories, this first imbalance effect of the rotor can be accompanied by a second phenomenon of imbalance, a little more brutal, caused by the sudden detachment of one or many blocks of previously joined materials with the pallets. This second phenomenon provides a strong and violent imbalance of the rotor, particularly dangerous for large capacity apparatuses where the diameter of the blades currently reaches three meters and a rotation speed of at least 1000 turns / minute. For all the situations mentioned above, without limitation, the occurrence of vibrations well above the limits of the functioning of the devices quickly requires the stopping of the fan and, consequently, the arrest of all or part of the industrial production unit in order to proceed with the cleaning of the pallets or the rebalancing of the rotor. On the other hand, the operations of cleaning or rebalancing the rotor, are long and particularly delicate tests. The delays due to immobilization of the ventilator have a duration that, over the industrial and economic plan, generate a significant cost that is difficult to bear. The need to solve the aforementioned problems quickly and efficiently for turbomachinery, such as industrial fans, has become imperative. Thus, it has been proposed to realize a dynamic and weight balancing device for an industrial fan capable of continuously and automatically controlling the unbalance / equilibrium state of the fan in operation, and of proceeding also continuously to the necessary balancing correction operations. Such a device requires at least one balancing unit in the form of a ring, carried by the shaft supporting the rotor, that is, the ventilation path. The balancing ring carries, as an equilibrium element, a high density fluid capable of rapidly vaporizing on contact with heat devices installed in the fluid spill circuit. A system for controlling and correcting the imbalance state of the rotor includes a microprocessor, measures the vibration level of the fan and determines the location of the imbalance. The control and correction system then ensures the electrical supply of the heat device located in the vicinity of the place where the imbalance was found in order to ensure the vaporization of the fluid located in a cooling chamber located in an opposite area where it is located. it condenses again and thus returns to its initial liquid state. This phenomenon of fluid transfer ensures the balance of the rotor. Such a device makes a real contribution to the control of the imbalance of a rotor, but nevertheless proves to suffer a certain number of drawbacks linked in particular to the impossibility of releasing the particularly harsh and extreme environmental conditions in which the imperatives must necessarily operate. industrial fans. Thus, the conditions of variation of extreme temperatures suffered by industrial fans can negatively affect the accuracy of the balance control or the rebalancing of the rotors of industrial fans that have resorted to an equilibrium by condensation / vaporization of fluids. On the other hand, the correction of the balance of the fan is linked to the point transfer of the fluid from a hot point to a cold point of condensation, the precision of the controls of such a device is limited by reason of the equally limited number, on the periphery of the ring, of the cooling chambers. In other words, the rebalancing of the rotor is done through equilibrium zones in the periphery of the equilibrium ring, and not punctually continuously over the entire periphery of the ring, which leads to an inaccuracy in relation to equilibrium. Finally, it is necessary to note the relative fragility of an equilibrium system that requires a fluid circuit in which the quality of the stagnation must be perfect, as well as the operating conditions of the industrial fans that imply environmental and environmental conditions. particularly difficult and corrosive. It seems last that the equilibrium capacities of fluid systems are limited to industrial fans with reduced capacity. In a technical field different from that of industrial fans and for machines that need a weak equilibrium capacity, namely grinding machines, it is already known to have the resource of two equilibrium rings and an imbalance detection system that includes a microprocessor that orders the displacement of the rings. In this modality, the balance unit is mounted inside and in the same body of the rectifier path. These solutions do not adapt to the important mass balance and operating conditions in a difficult environment. DESCRIPTION OF THE INVENTION The object of the invention seeks to remedy the drawbacks listed above, and propose a novel device of dynamic and weight balance for rotor machines where the control of the correction force can be performed with precision. Another object of the invention seeks to propose a new balancing device capable of freeing in the best conditions of the environment, and able to perform with a good precision, the balance of rotors in extreme conditions. A complementary object of the invention seeks to propose a new balancing device capable of rapidly and with confidence assuring the balance of rotors of important mass. The objects assigned to the invention are achieved with the aid of a dynamic and weight balancing device for machines with a rotor, in particular for industrial fans, which have at least one rotor supported by a rotary shaft, at least one unit of weight balance carried by said shaft, and at least one control and correction system of the imbalance state of the rotor, said system being able to act permanently on the balancing unit (s) when the rotor is rotating to control and correct the balance of the rotor characterized in that the balancing unit is located at an axial distance from the rotor to be balanced and is formed by a ring in which the equilibrium masses move independently of one another according to the paths forming a closed circuit around the rotating shaft under the action of the means of entrainment associated with each mass, to guide it in at least one guide means . BRIEF DESCRIPTION OF THE DRAWINGS Other details and advantages of the invention will be described in detail in light of the description and the illustrative examples that are presented below, given solely by way of non-limiting examples, in which: Figure 1 represents a general perspective view of an industrial fan equipped with a balancing device according to the invention. Figure 2 shows, according to a plan view, the main elements that constitute the balancing device according to the invention and equipping an industrial fan. Figure 3 shows, according to a sectional view, an equilibrium ring according to a variant embodiment of an equilibrium ring according to the invention.

Figure 4 shows a detail of the embodiment of a second variant embodiment of an equilibrium ring according to the invention. Figure 5 illustrates, according to a partial plan view of an equilibrium ring, the details of embodiment of a balancing truck according to the invention. Figure 6 shows, according to a longitudinal cross section of an equilibrium ring, the details of realization of balance trolleys and their displacement in the balancing ring. Figure 7 schematically shows the assembly of the elements that make up the balancing device according to the invention. BEST WAY TO CARRY OUT THE INVENTION Figure 1 shows a general perspective view of an industrial fan, centrifugal type and double flow, including at least two fluid inputs 2,3 arranged on one side and another of a ventilation path 4 , mounted and supported in rotation by a rotating shaft 5 itself capable of being driven in rotation by means of a drive device (Figure 2), such as an electric motor 6, for example. Ventilation path 4, which forms the rotor, is mounted on a construction provided with an external cover 7 and conventionally includes a central disc 8 which can be cut-out and where the side faces are provided with a series of covered pallets 9. by jars of variable profile, appropriate to the type of centrifugal fan and the characteristics of the fluid to be ventilated. The inlets 2, 3 are generally in the number of two, and form the suction units of the centrifugal fan 1. Preferably, the centrifugal fans 1 are equipped at the level of the suction units, of flow regulation systems arranged in the stream. above the venting path and arranged in the suction chambers 10, 11 associated with the respective inlet 2, 3 respectively. The suction chambers 10, 11, include, in a conventional manner, a series of vanes or deflecting elements of the address and the routing of the fluid in order to significantly improve the performance of the fan. Such devices are well known in the prior art and consequently will not be described in more detail. The industrial fan 1 finally comprises, in a conventional manner, a filling outlet 12. In the following example, the dynamic and weight balancing device according to the invention will be described in a preferred application as an equipment of an industrial fan 1, it being understood that such a description is not limitative and can be applied to all types of machines with a rotor carried by a rotating shaft.

In the preferred embodiment shown in FIGS. 1 and 2, the fan 1 is equipped with two weight balancing units 20, 21, arranged outside the rotor and carried by the rotating shaft 5, all of which are in rotation carried by the latter. Advantageously, the balancing units 20, 21 are respectively located on either side of the rotor at axial distances, preferably equal to the latter, and to the drive walls 22, 23 of the rotor. In such a case, the balancing units 20, 21 are located in the vicinity of the blades 22, 23, such an arrangement allows reducing the mechanical care of the rotating shaft 5 and consequently reducing its diameter. Obviously, as a variant it is possible to arrange the equilibrium units 20, 21 closer to the rotor to be balanced, and for example, between said rotor and the blades 22, 23, and, to be chosen, from the same side of the same rotor or on one side and another of said rotor. In the same way, it is possible, by way of variant, to provide for the assembly of a single weight balance unit on the outside of the rotor, according to one or the other of the two arrangements described above, in the case, for example, of a fan with simple entry. Advantageously, the balancing unit or units 20, 21 are presented in the form of a ring 25 provided, as shown in FIGS. 3 and 4, of an external protective body on which are movably mounted, independently of one another, at least two equilibrium masses ml, m2, in the solid state and fixed and defined, under the action of dragging means 26. In the variant embodiment shown in Figure 3, the equilibrium masses ml, m2 are displaced, under the action of a drag element 26 such as a micromotor, associated with each mass, per guide, in at least one guide element 27 formed by a bearing track directly recovering or not, the internal periphery of the ring 25. The equilibrium masses ml, m2 are advantageously constituted by trucks 30 including a series of wheels 31 capable of being guided in or on the guide means 27. As a complementary variant, each truck 30 can be provided with sliding skids. The equilibrium masses ml, m2 are consequently displaced according to the trajectories forming a closed circuit around the rotating shaft 5, the path being substantially circular in the present case, the relative angular position of each trolley 30 being adjustable in the two circular directions In the middle of each micro-motor 26. Indicatively, the average mass of each truck 30 is of the order of 2 to 5 kilograms and can obviously vary depending on the equilibrium capacities required by the mass of the rotor to be balanced. Advantageously, the masses of each truck 30 are identical. It is understood that following the relative angular position of each truck 30 the resultant of the forces Fl, F2 exerted by the mass of each truck 30 produces a resultant force F (F = 2m wr cos_ß) of correction of balance of the rotor that is applied on the rotary tree 5. In this mathematical expression: m = the mass of each truck r = the distance from the center of gravity G of each truck 26 to the axis of the rotating shaft. w = the square of the angular speed of rotation of the tree ß = the angular position of each truck relative to the resultant force F. According to this equilibrium principle, the resulting equilibrium force F is zero when the two trucks are diametrically opposed, and maximum when they are side by side in relation to the vertical. Figures 5 and 6 show the details of embodiment of the structure of the trolleys 30 and of the balancing ring 25. Preferably, the trolleys 30 comprise the internal wheels 31b, for example a pair, and the external wheels 31a, for example also a pair, considering as a point of reference the fictitious center of the ring 25, each pair of wheels 31a, 31b being associated respectively with an internal bearing track 27b and external 27a. According to this variant of preferred embodiment, the ring 25 then has two bearing tracks advantageously made of a material whose coating is capable of withstanding very strong accelerations without deforming. The micro-motor 26 housed in each truck 30 is functionally connected to a control and correction system 55 of the unbalance state of the rotor and is provided with a force transmission member 40, such as a worm gear that is directly engaged or indirectly on a rack 42 concentric to the bearing tracks 27a, 27b, to ensure the angular displacement of the equilibrium masses ml, m2. Different variants of embodiment are considered without thereby departing from the scope of the invention. Thus, it is possible to realize the balancing units 20, 21 in which the bearing tracks 27 are not circular but form, for example, substantially elliptical paths. Generally, each balance ring 25 comprises at least two trucks 30, which are preferably of identical mass in each balance ring 25 and between each ring 25. It is possible, however, to increase the number of trucks per ring of balance and vary its mass at a time between each balance ring 25, as well as in each balance ring. It is also not essential, as in the variant embodiment shown in FIG. 3, that the pair of trucks 30 be moved on or in the same bearing track 27. Thus, the variant embodiment illustrated in FIG. 4 shows an embodiment in FIG. which each cart 30 that composes the pair of balance masses is displaced in the different bearing tracks, preferably located in different but parallel axial planes. In the variant shown in Figure 4, each cart 30 evolves at a variable distance from the rotating shaft 5 on circular paths, but not centered relatively to the axis of the rotation shaft 5. Thus, on Figure 4, the displaceable cart 30 ' on the bearing track 27 ', it is represented occupying a second position 30", while on the track 27, the cart 30 is represented occupying an approximate position and symmetrically opposite that of the sarret 30' are with respect to the rotation shaft 5 This variant embodiment has the advantage of allowing an angular positioning of the carts 30 'and 30 in which their average relative distance is weaker than in the single-track variant The approximate position of the carts 30' and 30 it is then particularly useful for the commissioning of the rotors in a perfectly balanced state since an approximate position allows to make small corrections of equilibrium with the The correlative reduced efforts applied to the mechanical structure in comparison with the variants of realization with single track. This allows a reduction of the applied stresses on all the pieces of the balancing units 20, 21 contributing to the longevity of the different components, and especially that of the bearing tracks 27. The balancing unit or units 20, 21 are under the control of a control and correction system 55 of the state of imbalance that is systematically presented in Figure 7, and whose main function is to evaluate the imbalance / balance state of the rotor, that is, the wheel of ventilation 4, and proceeding, preferably automatically, to the necessary corrections commanding and piloting the equilibrium masses ml, m2. Such a system preferably comprises: at least one sensor of a value representative of the imbalance state of the rotor. - a microprocessor responsible, on the one hand, for permanently evaluating the unbalance status of the rotor in comparison with measured values transmitted permanently by the sensor (s) with the previously recorded reference values, and on the other hand, if the result of the comparison makes a state of imbalance appears, of commanding and driving the displacement of at least one equilibrium mass ml, m2 just to the complete equilibrium of the rotor. - an electromechanical interface between: the sensor (s), the microprocessor and the entrainment means of the equilibrium masses ml, m2. Advantageously, the control and correction system of the unbalance state comprises as sensor less a vibration sensor 50 (Figures 2 and 7), and preferably two sensors each arranged in the vicinity of an equilibrium unit 20, 21. , on a flat trailing surface 22 on the rotating shaft 5. The vibration sensor (s) 50 is functionally connected to a microprocessor 51 having a calculation algorithm and a set of memory registers in which the reference data is stored. and, consequently, the vibration measurements that constitute a system of reference values for the development of the calculation algorithm. The electromechanical interface such as that shown in Figures 6 and 7 involves a contact 60 mounted on each balance unit 20, 21, connected to the microprocessor on the one hand, and susceptible to entering friction or rubbing relationship with the tracks of Sontasto 65 are electrically tested to the trucks 30 on the other hand. The contact 60 may, for example, be a rub ring fixed to reside in the balance ring 25., and for example in a lower chamber 66, to be in permanent contact with the contact tracks 65 after their displacement, or to be mounted movable for example with the help of a lever commanded by a jack 70 (figure 7) to come in contact with tracks 65 only if an imbalance condition is detected in the rotor. The control and correction system of the unbalance state, 55 may be connected to a PC-type computer 61 for example, to record and track the data made permanently by the balance measuring instruments as well as the corrections made. The system can also be connected to a control and remote control panel 62, for example allowing introducing or modifying the control or operation parameters of the device. The operation of the balancing device according to the invention according to a preferred example of a calculation algorithm is as follows. With the industrial fan running, the sensor or sensors 50 permanently provided with a microprocessor and at regular intervals, a series of vibration measurements of the machine. The microprocessor constantly compares the information required by the sensors 50 with their own reference data by means of which a limit value of vibrations is shown that must not be passed. When this maximum value is exceeded, it means that an unbalance state was detected, the microprocessor selects one or the other of the balance rings 20, 21 according to the sensor that detected the unbalance. The microprocessor 51 immediately commands and controls the displacement of a truck 30 in a given direction, the sensors 50 continuing to simultaneously send new instantaneous measurements of vibrations. The microprocessor 51 that permanently compares each new measured value of vibrations with its own reference system is arranged to determine whether the previous displacement of the truck has been to reduce or not reduce the value of the last measure of transmitted vibrations. If the last transmitted vibration value corresponds to a decrease in the state of the vibrations the microprocessor continues to ensure the displacement of the truck 30 in the same direction making sure that the overall level of vibrations has decreased. In the opposite case, the microprocessor changes the direction of travel of the cart 30 if the level of vibrations, in spite of the correction made, increases. The calculation algorithm then functions recurrently and is well known in order to quickly optimize the intent of an equilibrium result, the principle of balance retained by being constantly in a direction of displacement which reduces the level of vibrations. Although the measured vibration level expects a previously recorded minimum value, the automatic balancing procedure stops.

As a complementary variant, it is considered to use, as equilibrium masses ml, m2 instead of the forklifts 30, annular pieces of equilibrium, lightly punctually or cut off equally on the circumference of the pieces. In this case, the annular balance pieces are disposed, for example, in parallel between them around the rotary shaft 5, and for example in a number of two. Their relative displacement around the rotating shaft 5 causes the rebalancing of the rotor. In a general manner, the equilibrium masses ml, m2 can be constituted by all the movable parts mounted around the rotating shaft 5 and can include palansas or light arms. Neither is it essential to have the use of a microprocessor, of the control and correction systems of the unbalanced state 55 being simplified. to agree, such systems based on analog circuits that involve an automatic or even manual order of displacement of the equilibrium masses ml, m2. The dynamic and weight balancing device according to the invention, as well as the corresponding balancing method, consequently allows to control with precision and in real time in a fast and reliable way the necessary forces to correct the imbalance of high mass machines. The possibility of rotation of the trolleys 30 over the entire periphery of the bearing tracks 27 allows, together with the use of a microprocessor, a particularly precise correction of imbalance of a rotor. The balancing device is, on the other hand, particularly well protected against environmental aggressions, which contributes to the reliability and longevity of the device. POSSIBILITY OF INDUSTRIAL APPLICATION The invention finds its industrial application in the manufacture of machines with rotor of all kinds, such as turbomachinery and in particular in the manufacture of industrial fans.

Claims (10)

1. CLAIMS 1. Device for dynamic and weight balancing for machines with rotor, in particular for industrial fans, comprising at least one rotor (4) supported by a rotating shaft (5), at least one unit of weight balance (20, 21) held by said shaft, and at least one control and correction system (55) of the imbalance state of the rotor (4), said system being able to act permanently on the balancing unit (s) (20, 21) when the rotor (4) is in rotation_ to control and correct the balance of the rotor (4), the weight balance unit (20, 21) comprises at least two equilibrium masses (ml, m2) mounted movable under the action of drag elements (26) ) commanded by the control and correction system (55) because the balancing unit is located at an axial distance from the rotor (4) to be balanced and formed by a ring (25) in which the equilibrium masses (ml, m2) move independently of each other according to the trajectories forming a closed circuit around the rotating shaft (5) under the action of the driving means (26) associated with each mass (ml, m2) to be guided in when less a guide means (27).
2. 2. Balance device according to claim 1, characterized in that it comprises at least two balance units (20, 21) located respectively on each side of the rotor (4) to be balanced.
3. 3. Balance device according to claim 2, characterized in that the balance units (20, 21) are located beyond the dragging walls (22, 23) of the rotor (4), preferably at an equal distance from said rotor. Balancing device according to one of Claims 1 to 4, characterized in that the balancing masses (Ml, m2) are constituted by trolleys (30) or by annular pieces. Balance device according to claim 4, characterized in that the trolleys (30) comprise a series of wheels (31) capable of being guided in the guide means (27) formed by one or the bearing tracks. Balance device according to claim 5, characterized in that the trolleys (30) comprise internal wheels (31b) and external wheels (31a) considering the center of the ring (25), associated respectively with an internal raceway (27b) and external (27a). Balance device according to one of claims 5 or 6, characterized in that the bearing tracks (27) form a substantially circular path around the rotating shaft (5). Balance device according to one of claims 5 to 7, characterized in that the bearing tracks (27) form substantially elliptical paths. Balance device according to one of claims 6, 7 or 8, characterized in that it comprises at least two trucks (30) per balance ring (25), the two trucks (30) of identical mass being preferably in each ring ( 25) and between each ring (25). Equilibrium device according to one of claims 5 to 9, characterized in that the trucks (30, 30 ') move on different tracks (27, 27'), preferably located in different but parallel axial planes. 12. Balance device according to claim 11, characterized in that the bearing tracks (27, 27 ') are non-concentric with respect to the rotating shaft (5) and preferably circular. An equilibrium device according to one of claims 1 to 12, characterized in that the driving means (26) comprises a micromotor, housed in each equilibrium mass (ml, m2) and functionally connected to the control and correction system (55) of the imbalance state of the rotor (4). 14. Balance device according to claim 13, characterized in that the micromotor (26) is provided with a force transmission member (40) engaging on a rack (42) concentric to the bearing tracks (27a), 27b) to ensure the displacement of the equilibrium masses (Ml, m2). Equilibrium device according to one of claims 1 to 14, characterized in that the control and correction system (55) of the unbalance state comprises: - at least one sensor (50) with previously registered reference values, and on the other hand part, if the result of the comparison results in a state of imbalance, of commanding and driving the displacement of at least one equilibrium mass (ml, m2, 30) just to the complete equilibrium of the rotor (4). - an electromechanical interface (60) between the sensor (s) (50), the microprocessor (51) and the entrainment means of the equilibrium masses (ml, m2, 30). 16. Balance device according to claim 15, characterized in that it has, as sensor (50), at least one vibration sensor, and preferably two sensors, each arranged in the vicinity of an equilibrium unit (20, 21) on a bearing of drag (22, 23) or on the rotary shaft (5). An equilibrium device according to claim 15 or 16, characterized in that the electromechanical interface comprises a contact (60) connected to the microprocessor (51 on the one hand and mounted on each balance unit (20, 21) and capable of being electrically connected to the equilibrium masses (ml, m2, 30) on the other hand 18. Balance device according to claim 17, characterized in that the contact (60) is a rubbing ring in permanent contact with the contact tracks (65) where Mounting device for coming into intermittent contact with the contact tracks (65) only if an unbalanced state is detected 19. Balance device according to one of claims 1 to 18, characterized in that it is known to be dimensioned to ensure a correction of equilibrium at least equal to 100 000 g.mm, and preferably between 10 000 g.mm and 5 000 000 g.mm. 20. Industrial fan equipped with an equili device according to one of claims 1 to 19.