WO1994001225A1

WO1994001225A1 - Device for exciting vibration

Info

Publication number: WO1994001225A1
Application number: PCT/EP1993/001693
Authority: WO
Inventors: Hubert Bald
Original assignee: GEDIB Ingenieurbüro und Innovationsberatung GmbH
Priority date: 1992-07-03
Filing date: 1993-07-01
Publication date: 1994-01-20
Also published as: DE4301368A1

Abstract

Device for the excitation of vibrations in a frame in a predeterminable direction with a motor drive and a degree of imbalance which is adjustable during operation, whereby the unbalanced masses are divided into partial unbalanced bodies. Special steps concerning the drive of the partial unbalanced bodies can reduce shock loads on the drive components caused by reactive torque and hence noise emissions arising therefrom. For use in ram vibrators and vibration benches, e.g. for moulding machines.

Description

Vibration excitation device

The invention relates generally to a device for

Vibration excitation of a device frame in a predetermined direction and in particular a device in which the resulting centrifugal force MR determining the centrifugal force FR is adjustable (FR = ME xw ² , with w as the angular velocity).

Such devices are used e.g. as vibrating vibrators in molding machines or as ramming vibrators.

Two are required to generate a directional vibration

Imbalance bodies, each with a centrifugal moment M, which must be forced into an angularly synchronous revolution with the opposite direction of rotation by suitable means. If an adjustment of the centrifugal torque MR is required, each of the unbalance bodies must be replaced by a pair of two partial unbalance bodies (first and second type unbalanced bodies).

Each partial unbalance body has a partial centrifugal moment with the absolute amount j M / 21 = mu x | e | , where mu represents the (point-concentrated) unbalanced mass and | e | the distance of the center of gravity of the unbalanced mass from the axis of rotation. Since e can be understood as a vector, the centrifugal moment M / 2 is also to be regarded as a vector, as is the centrifugal force F = mu xexw ² that occurs when a part unbalance body rotates at the angular velocity w.

The adjustability of the centrifugal torque MR is expressed by the fact that the partial actuating moments of each pair can have different directions.

In order to change the vectorial sum of the partial centrifugal moments of each pair between the value zero and the maximum value M, the associated actuator of a corresponding oscillation device between the partial centrifugal moments has a relative actuation angle β = zero and β = 180 ". -?

The vectorial sum of the partial centrifugal moments of both pairs gives the resulting (total) centrifugal moment MR with the maximum value MR.ΠUUC

Vorrichtung A device for generating directed vibrations with an adjustable centrifugal moment MR therefore requires at least 4 rotatable partial unbalance bodies, which is why the present invention is also explained using examples with 4 partial unbalance bodies each. Of course, the invention also extends to vibration excitation devices in which C the at least two necessary pairs or the at least two partial centrifugal moments required per pair are distributed over a larger number of pairs or rotatable partial unbalance bodies.

The known prior art closest to the present invention is shown in the publication PCT / EP 90/02239. A device for vibration excitation is described here, in which the at least 4 necessary partial unbalance bodies can also be adjusted by means of several actuating motors which are actuated in parallel. A predetermined, maximally adjustable resulting centrifugal moment MR.max results when a relative setting angle β = 180 ° is set.

A simple, robust and inexpensive operating mode results when, for the purpose of setting a predetermined resulting centrifugal torque MR, the actuating motors are impressed by means of the actuating device with an actuating torque which is in equilibrium with the reaction torque which results when the centrifugal torque MR is set MR stands.

In this control process, it is therefore sufficient if, in the case of hydraulic servomotors, a specific pressure which determines the actuating torque is impressed on them. With this type of control of the relative actuation angle β, several actuators can then be acted upon by the same pressure.

A disadvantage of this control method has been found that in the range of values above β = 90 °, it is not possible to maintain predetermined values for the relative setting angle β without the addition of additional control aids. If the fulfillment of the function is forced with additional control-technical effort such that relative positioning angles β greater than 90 ° can be controlled, This results in additional difficulties for the range β = 90 ° to β = 180 ° as a result of the torque fluctuations then occurring from the control process and as a result of alternating torques, which will be described later.

A device for vibration excitation has become known from patent specification DE 41 16 647 C1, in which each of the 4 partial unbalance bodies is assigned its own electric servomotor.

The servomotors equipped with angle measuring systems are torsionally rigidly connected to the unbalanced shafts carrying the four partial unbalance bodies, and a position control system which is superior to all four servomotors regulates the angular position of all motors in such a way that the part unbalanced bodies forming a pair in a symmetrical manner adjusted or held in a symmetrical angular position.

A relative setting angle ß can easily be set to any value between ß = 0 ° and ß = 180 °. A predetermined, maximum adjustable resulting centrifugal moment MR, Ba results when a relative actuation angle β = 180 ° is set.

With this adjustment strategy, the angular position of one of the 4 motors is regarded as an independent variable (reference variable), while the angular position of the 3 other motors is regarded as dependent or variable variables (subsequent variables).

So that the 3 dependent angular positions always remain at the prescribed setpoint under the influence of disturbance variables, which also include the reaction torques MR, each servomotor must be permanently acted upon by its own controller.

Since the oscillating common dynamic mass mg provides an energetic coupling of all partial unbalance bodies to one another (transformer effect), such that the three other partial unbalance bodies also want to be adjusted by adjusting the angular position on one partial unbalance body, all controllers are constantly correcting angular deviations in both directions. The resultant demands on the dynamics of the controllers are exacerbated by the fact that the definition of the angular position of one of the unbalanced shafts as the guide variable and the control-related tracking of the subsequent quantities of the 3 other angular positions to asymmetrical loads to lead. As a result of the necessary highly dynamic control, there are ongoing changes in the rotational speeds and torques on the motors.

The person skilled in the art is aware of the negative effects of the resulting torque I C jumps on the drive elements. The stress on the drive elements is particularly high if the motors are to be arranged in a stationary manner (that is, they are not oscillating) and nevertheless a torque-resistant torque transmission between the servomotor and the unbalanced shaft must take place via suitable drive elements.

15

The type of vibration excitation devices characterized by the DE-PS 41 16 647 Cl with adjustable resulting centrifugal moment MR and with its own servomotor assigned to each partial unbalance body has the two disadvantages mentioned below: 0

The adjusting devices for regulating or controlling the relative setting angle β are very complex or also very expensive.

It is evident that high dynamic loads act on the drive elements involved (e.g. 5 gearwheels, toothed belts, cardan shafts), which lead to rapid wear and tear or the rapid uselessness of the drive elements and, at the same time, are responsible for high noise emissions.

The invention makes it its task to improve the type of vibration excitation devices characterized by the examples described above. The improvement should on the one hand help to keep the costs and the equipment-related expenditure for influencing the relative setting angle β low and on the other hand also have the consequence that the abovementioned wear and noise problems, the causes of which in the The existence of alternating torques are to be sought. Before the solution to this problem according to the invention is dealt with, an attempt should first be made to address the theoretical causes of the difficulties mentioned.

In PCT-OS PCT / EP 90/02239 it is explained with reference to FIG. 4 for a device for vibration excitation with 4 part unbalance bodies that between the partial unbalance bodies of the first and second types caused by mass forces Torques MRi and MRπ act. (However, it should be noted that the angle β identified there is identical to the angle α used in the description of the present invention).

These known theoretical considerations are to be expanded below with reference to FIGS. 5 and 6.

The reaction torques MR occur as alternating torques with a sinoid profile over the angle of rotation μ with a frequency twice as high as the rotational frequency, that is to say with two peak values per revolution (see FIG. 5). The absolute magnitude of the reaction torques MR depends on the dynamic mass mg, on the angular velocity w, on the centrifugal moment MR and on the relative actuation angle ß.

Fig. 5 shows the course of the reaction torque MR as a function of

Angle ß for the angle values ß = 30 ^* , 90 ^* and 180 °. (The meaning of the angles α and ß used below can be seen clearly from Fig. 1. While α and ß are indicated by the adjustment angle, the angle μ is the common angle of rotation of the unbalanced shafts.)

The examples indicate that up to MR = f (ß = 90 ^* ) with increasing angle ß, both the amplitude values of the alternating moments increase and the proportion of negative MR values increases.

From the function course for MR = f (ß = 90 ^* ) to MR = f (ß = 180 ^# ), the amplitude values decrease. It is more remarkable, however, that the negative MR values increase continuously with increasing angle ß until finally at ß = 180 ^* the proportion of positive MR values equals the proportion of negative MR values. If you integrate the function of MR over the rotation angle 2π, you get the so-called angular momentum D. If you divide the value for D by 2π, you get an average reaction torque MR.

The size of MB corresponds to the size of the actuating torque MD on the unbalanced shaft, which must be applied by an adjusting motor in order to maintain the associated relative part angle β.

If, according to FIG. 5, the average reaction torque MR is determined for all values of β and the values for MR are plotted over the angle β, a curve profile as shown in FIG. 6 is obtained. The curve for the function MR = f (.beta.) Is at the same time a measure of the actuating torque MD = f (.beta.) [With MR = -MD1.

It is remarkable in FIG. 6 that the decrease in the function value for MR after the maximum point MP has been exceeded from the maximum value to the value zero at β = 180 "is not primarily due to a decrease in the amplitude values of the corresponding ones 5, but mainly due to the fact that the positive and negative MR values are more and more balanced as the value for angle ß increases, and it can be mathematically proven that the maximum point MP at ß = 90 ° must lie and the curve is a pure sine line.

From FIG. 6 it can be seen from the curve for MD = f (β) [= -MR] for an operating point APi to the left of the maximum point MP that an angle BAI is set at the actuating motor with an impressed actuating torque MDAI, whereby no regulation is required for compliance with this assignment.

The stability of the operating state that can be achieved without regulation at a given constant value for MDAI can be explained by the behavior in the event of deviations in the value of BAI upwards or downwards: If BAI tends to larger values, the resetting reaction torque MR also increases and ensures a reduction from BAI. If BAI tends to smaller values, the internal restoring torque MR also decreases, so that the BAI value must inevitably increase again under the influence of the actuating torque MDAI. However, the operating behavior at a working point APπ on the descending curve branch looks completely different:

If the angle BAU tends to larger values, the resetting reaction torque MR decreases, which, because of the excess MDAΠ which now arises compared to the current value of MR, leads to acceleration of the adjustment rotation of the corresponding partial unbalance body, as a result of which the angle ß automatically increases further. A similarly negative operating behavior arises in the event of deviations in the value QAΏ. from the setpoint to smaller values. The working point APπ can only be kept stable, particularly in the right part of the descending curve branch, only with counter-rules with a negative actuating torque.

The stable adjustment of an operating point on the right-hand curve part of the MD = f (ß) function requires, on the one hand, a real controller (with feedback of the actual value of the controlled variable ß) and, on the other hand, is caused by the ongoing sign change of the actuating torque MD an ongoing load reversal on the gear parts, which leads to undesirable high dynamic loads due to the mostly existing backlash.

In comparison, even higher dynamic loads result from the course of the reaction torques MR = f (ß, μ) over the rotation angle μ:

The following relationships can be seen from FIG. 5: The peak values of the reaction torques MR = f (β, μ) exceed the size of the average reaction torque MR = f (ß), which for the example MR = f (ß = 90 ^* ) is shown by hatching.

Since the size of MR can be equated with the constant actuating torque MD, the effect of the torques can be seen using the example MR = f (ß = 90 ^* ) and MD = f (ß = 90 ^* ) in the event that No play occurs when the power is transmitted through all of the drive elements involved, as follows:

Both torques act in the opposite direction on the rotatable masses. During phase 1 to 2 (in FIG. 5), MR and there is an additional acceleration of the rotating masses by MR, which manifests itself in an increase in the angular velocity by the amount delta-w (see also the curve for delta w in FIG. 5).

During the phases 2 to 3, the (decelerating) actuating torque MD predominates, whereby the increase in the angular velocity w by the amount delta-w is reversed again.

However, if there is a backlash in the chain of power transmission through all the drive elements involved, which is usually always the case, not only is there a force or torque curve, as shown in FIG. 5, but striking stresses occur with a great deal higher peak values. Because with the presence of backlash, the "smoothing effect" of MR is often no longer guaranteed, and the energy of the swirl (corresponding to the area under curve "A" from 0 to 2a in FIG. 5) settles through mass acceleration completely converted into kinetic energy.

This explains to a large extent the cause of the negative effects of dynamic loads in the

Drive elements of vibration excitation devices which can be changed with regard to their centrifugal torque MR.

The rotational angle deviations delta-μ associated with the angular velocity deviations delta-w are typically in the range between 0.5 ^* and 1 ^* , which can be an amount greater than the tooth play, for example, in the case of gear wheels used as drive elements. The deviations each represent the differences between a partial unbalance body of the first type and the second type.

The ratios in the cited example ß = 90 ^* do not yet represent the sharpest alternating loads. These occur with increasing value for angle β, the amplitudes of the alternating torques hardly decreasing, but the size of the average reaction torque MR, the latter even reaches zero at ß = 180 ^* . With decreasing MR, the effect of the alternating moments increases. The solution to the problem is defined in independent patent claims 1 and 6 and is based on the concept described below:

a) To set and maintain a predetermined relative

Adjustment angle ß with the help of the higher-level actuating device, each actuating motor is impressed with a unidirectional actuating torque MD, the direction of the actuating torque acting in such a way that an increase in the actuating torque results in an increase in the relative actuating angle ß Has.

b) _> The partial centrifugal moments are dimensioned (by up to 30%) larger than is actually absolutely necessary, in such a way that for the purpose of setting the intended maximum and permissible resulting centrifugal moment M, ma_κ an adjustment of the relative Adjustment angle ß is only necessary up to about 90 °.

c) The limitation of the relative setting angle ß has the consequence that the effects of the reaction torques MR, or also the effect of production-related or use-related play (backlash) leading to dynamic loads on or between such drive elements which the Synchronization of the angle of rotation of two partial unbalance bodies of the first type or the second type of a pair each (for example on gear wheels, toothed belts cardan shafts) can be reduced or canceled at the latest after the predetermined relative setting angle β has been set.

d) The avoidance of disadvantageous alternating torques is also achieved by utilizing internal forces acting automatically in the range of a relative actuation angle ß of less than 90 ° (due to the dynamic mass mg resonating). When the servomotors are subjected to actuating torques symmetrically, the symmetry of the adjusting rotation angles of all partial unbalance bodies is in such a stable state that in principle other synchronization means can be dispensed with entirely (as explained in FIGS. 1 and 4).

According to claim 1, the drive members can be freed from the load on the reaction torques MR practically completely by assigning a separate servomotor to each partial unbalance body, with the Actuators assigned to the partial unbalance bodies of the same type are transmitted to the partial unbalance bodies actuating torques MD with the same amount, but with different directions of action, and the amounts of the actuating torques MD with the relative actuating angle ß being kept constant being the average reaction Torque. Correspond to MR of the assigned partial unbalance body.

With the means according to claim 6, the effect of dynamic loads from backlash can be reduced or eliminated in that, when the predetermined relative setting angle βmax is reached, at least one pair moves against a stop limiting the relative setting angle β and the stop position with one setting Torque is tightened.

In principle, a device according to claim 1 surprisingly does not require any additional synchronizing means for synchronously guiding the angles of rotation of all partial unbalanced bodies. The synchronism of the relative actuation angle β is ensured by the reaction torque MR, which is of the same magnitude for each pair, or by the counteracting actuation torque ^" MD, while the synchronous position of the angle of both pairs is brought about by those inertial forces resulting from The tendency to inertia of the dynamic mass mg acting jointly on both pairs can be explained, taking into account that the oscillating dynamic mass mg continuously and alternately impresses, and thus synchronizes, the partial imbalance bodies with rotational accelerations and rotational delays.

Although synchronizing means are not required for synchronizing the angles of rotation, it can nevertheless be expedient to provide such as a safety measure. In FIG. 2, as also in FIG. 4, two partial unbalance bodies of the same type and two pairs of gearwheels are provided as safety measures. These gearwheels normally do not transmit any synchronization forces or other forces and can therefore also be operated without the addition of lubricant. They only have the task of ensuring synchronous operation in emergencies in the event of external disturbances.

In contrast to the invention according to DE-PS 41 16 647 Cl, feedback of the actual angle of rotation is not in the present invention necessary, as a position control with respect to the angle of rotation does not take place.

The possible parallel loading of several motors, as well as the application of the principle of control (instead of regulation), make the main contribution with regard to simplification and cost reduction when using a device according to the invention.

The advantages that result from the limitation of the adjustment range essentially to values between 0 ° and 90 ° for the relative adjustment angle β also include the fact that the range with the highest alternating moments MR is avoided. [See also MR = f (β = 180 °) in FIG. 5]

The additional use of a stop limiting the relative setting angle β can be useful for several reasons. For example, one can set angle ß> 90 ° or, at ß <90 °, protect a desired relative setting angle ß against changes due to various conceivable disturbance variables.

In the solution according to patent claim 6, the relative setting angle β is limited by a stop, two stop members being clamped with a torque generated by the servomotors.

In order to be able to vary the relative setting angle ß with this solution, one can move or change the stop itself.

A simple solution is obtained if one of the stop organs is arranged to be parallel or coaxially displaceable with respect to an axis of rotation of the device, for which purpose the stop element cannot also be attached in a rotating manner.

Such a variable stop could also be used for a device according to claim 1.

The subclaims define further preferred refinements of the concept according to the invention.

The following further developments of the invention, which are taken into account in the subclaims, should be particularly emphasized: It can be very useful to operate servomotors as drive motors at the same time. It should be borne in mind that the servomotors have to apply an actuating torque MD to the partial unbalance bodies of one type with the opposite sign as to the partial unbalance bodies of the other type. Since the actuating torques MD are torques that can only be used to a limited extent for useful work, it makes sense to have the actuating torques MD supported against one another by means of a series connection of the servomotors. The easiest way to do this is to use hydraulic motors. How a pressure distribution with regard to the actuating torques and the working drive torques can look is described in detail for a hydraulic solution using a specific example in OS PCT / EP 90/02239 (page 14).

- Since the rotation angle is synchronized (up to a possible

Stop) exclusively via the size of the actuating torques MD or the magnitude of torques derived from mass forces, the drive means by means of which the torques are guided from the actuators to the shafts of the partial unbalance bodies, the moments do not necessarily have to be transmitted in the correct angle.

It is therefore possible to use V-belts without having to accept the disadvantages of the slippage that occurs during their use.

- As servomotors, which have to generate their actuating torque MD on the one hand in the direction of the direction of rotation and on the other hand against the direction of rotation, are particularly suitable (commercially available) three-phase motors which, when setting the angle β from the actuating device, have two different ones Three-phase systems are applied, wherein one of the three-phase systems can be identical to the normal local network.

When used as pure servomotors, the three-phase motor operated directly on the network - working as a generator - could supply the energy supplied to the servomotor operating at a higher frequency back into the network (apart from the conversion and friction losses which are always accepted). Since in this case the motor slip determines the torque and consequently also the actuating torque MD, the frequency difference would be a measure of the relative actuating angle ß.

The advantage of this operating mode remains when using three-phase asynchronous motors even if the asynchronous motors are servomotors and working drive motors at the same time. An application is particularly advantageous when electric motors are preferred because of the costs and / or the function and at the same time an electrical adjustability of the speeds is also desired.

In principle, a vibration excitation device with the features according to claim 1 does not require any synchronization means for synchronously controlling the angle of rotation of the partial unbalance bodies of one pair relative to the other pair. This property makes it possible to set different relative setting angles β for both pairs.

This results in the possibility of changing the direction of the directional vibration relative to the device frame. Applications for such a vibration direction controllability arise e.g. in vibrators for soil compaction, in which not only the vertical vibrating intensity varies, but also a horizontally acting acceleration component for the displacement feed can be generated.

In the case of molding machine vibrating tables, the controllable vibration direction can be used e.g. horizontal vibrations can also be excited.

Exemplary embodiments of the invention are explained in detail below with reference to the drawings.

Fig. 1 shows schematically a vibration excitation device with 4 partial unbalance bodies and 4 hydraulically operated motors.

FIG. 2 shows, in a section in FIG. 3 marked E-F or K-L, perpendicular to the axes of rotation, a device for excitation of vibration with two pairs of partial unbalance bodies with partial unbalance bodies arranged coaxially for each pair.

Fig. 3 is the section through a device according to Fig. 2 according to the cut marked there with G-H.

Fig. 4 shows schematically a device according to the invention with 4 electric motors and their control by means of a frequency converter. FIG. 6 shows diagrams of the course of reaction torques, plotted against the angle of rotation μ of the unbalanced bodies.

FIG. 6 shows diagrams for the course of the necessary actuating torque MD and the resulting centrifugal torque MR over the relative actuating angle β.

In Fig. 1 4 shafts 116 to 119 are mounted in a frame 109 with masses, with unbalanced bodies 101, 102, 105, 106 of the same size with respect to their partial centrifugal moment.

Each of the 4 shafts is assigned a hydraulic motor 103, 104, 107, 108 of the same torque. The direction of rotation of the shafts is marked with w (w for angular velocity).

The Teü unbalance bodies 101 + 105 and 102 + 106 each form a pair (in the example also characterized by the same rotation directions) with partial unbalance bodies of the first type 101 or 102 and the second type 105 or 106, between which a relative - Setting angle ß is to be set (angle α is complementary - angle α = 180 ° -ß).

A unit for generating two separate fluid volume flows is provided, with an electric drive motor 110, a pump 115 with a constant delivery volume and a pump 214 with a variable one

Delivery volume, which can be predetermined electrically by the setpoint generator 213. The pressure at the outlet of the pump 115 can be adjusted with a pressure limiting valve 111. The pressure in the line part 117 can be set as desired within certain limits via an electrically controllable pressure control valve 112.

The motor groups assigned to the two pairs are acted upon by the pump 114 in parallel and with the same inlet pressure at the motors. The motors of each pair are connected in series. In this way, all motors are given the same rotational speed, which in turn can be varied by changing the delivery volume of the pump 114.

The mode of operation of the device according to FIG. 1 is as follows: The technical teaching according to claim 1 is used. The hydraulic motors are used both as working drive motors and as servomotors. For safety reasons, the partial unbalance bodies 101 and 102 may be forcibly synchronized by means of two gear wheels each assigned to a shaft 117 and 118 (indicated by the contact of the circles symbolizing the partial unbalance bodies). Since no forces are normally to be transmitted via these gears, this type of forced synchronization could also be omitted.

It is assumed that the pressure at the outlet 117 of the pressure control valve 112 is initially lower than in the line part 118 and that all the motors rotate at the same speed, the relative actuating angle β also initially having the value zero.

In line parts L3 or Li and L ₂ , pressures have built up, which are primarily determined by the theological conditions and by the friction generated during the rotation of the rotating parts.

If a pressure is now set at the outlet 117 of the pressure control valve 112 that is greater than the pressure prevailing in the line part 118, the motors 103 and 104 must additionally work against this pressure, which means that the motors operate at the same time as pumps (generator operation). indicates what you need the additional torque MDp for.

Due to the pressure increase at Li or L2, the motors emit an additional torque MDM.

The action of the additional torques MDp and MDM produced the relative setting angle β on each pair, which in turn caused a reaction torque MRI on the partial unbalance bodies of the first type 101, 102 and on the partial unbalance bodies of the second type 105, 106 a reverse reaction torque MRπ occurred.

With the amount of pressure on the line part 118, the angle β can be set as desired within the range 0 ^* and 90 ". As can be seen from FIG. 1, the reaction torques are opposite to the additional torques, the respective amounts of the opposite torques being the same. The additional torques represent the actuating torques MD (MD = -MR).

After conversion by internal forces acting on the frame, the additional torques MDM to be applied by the motors 107 and 108 are fed back to the motors 103 and 104 as additional torques MDp.

It can be seen that, for each pair, it applies that an apparent power corresponding to the product Ps = MDM x w = MDp x w is continuously circulated on a closed transport path (shafts, frame, motors, lines Li or L2).

(For an explanation of the pressure ratios in front of and behind the motors, see also OS PCT / EP 90/02239, page 14).

FIGS. 2 and 3 show a vibration excitation device according to the invention, which represents a special variant of the device shown in schematic form in FIG. 1.

It is a variant in which the partial unbalance bodies of each pair are arranged coaxially.

In Fig. 2, the left part of the drawing corresponds to the cut E-F and the right part of the drawing of the cut K-L. 3 shows a frame composed of parts 209 and 219 with roller bearings 202 and 206, in which a split shaft with the partial shafts 216 and 217 is supported.

Coaxial guidance of the two partial shafts with the possibility of a relative rotation relative to one another is achieved in that the right shaft end 220 of partial shaft 216 is supported in two needle bearings 211, while the needle bearings in turn are in a bore 210 of the hollow cylinder end. the 207 of the partial shaft 217 can roll.

On the hollow cylinder end 207, two unbalanced bodies 201 a and 201 b with the same centrifugal moment are attached with the same center of gravity (see also FIG. 2). There is one between them further unbalanced body 205 with a centrifugal torque twice as large as that of unbalanced body 201 a and with a center of gravity arranged rotated by 180 ^* (based on unbalanced body 201 a), and in such a way that it - supported with a needle bearing 218 - relative to the Part shaft 217 is rotatable.

The unbalance body 205 is connected to the partial shaft 216 in a torque-transmitting manner, which is accomplished by a stop pin 213. This is pressed with two stepped cylinder parts into a bore 224 in the unbalanced body 205 and into a bore 222 in the disk part 212 of the part shaft 216.

The arrangement shown in FIG. 3, together with the storage with the roller bearings, is accommodated twice in the same embodiment in the frame 209/219, as can also be seen from FIG. 2, where the same parts of both groups are identified by the same reference numbers. Both groups sir, forcibly synchronized by two intermeshing gears 204, 204 'with pitch circles 226, 226'. As can be seen in FIG. 3, the gearwheels 204, 204 'are firmly connected to the partial shafts 217, 218.

The rotatability of the unbalance body 205 relative to the unbalance bodies 201 a and 201 b is limited by a stop which is formed in that after a relative rotation of β = 90 ^* from the position shown, the stop bolts 213 (by the circle 228 symbolized) comes to rest against a stop surface 230 on the unbalance body 201 a.

As indicated schematically in FIG. 3 with the motors 203 and 207, 4 hydraulic motors are present and are connected to the 4 partial shafts 216, 219, 217, 218 in a torque-transmitting manner.

In comparison with the arrangement in FIG. 1, the following correspondences result for the device shown in FIGS. 2 and 3:

Waves 117 and 118 or waves 116 and 119 are the partial waves 217 and 218 or 217 'and 218'.

Motors 103 and 104 or motors 107 and 108 are motors 203 and 203 'or 207 and 207'. The partial unbalance bodies 101 and 102 correspond to the two-part partial unbalance bodies 201 a and 201 b or 201 a 'and 201 b \ The partial unbalance bodies 105 and 106 correspond to the partial unbalance bodies 205 and 205'.

The mode of operation is the same as that described for FIG. 1. However, the motors could also be electric motors and then e.g. can also be operated as described for the arrangement according to FIG. 4.

The drawn position of the focal points in FIGS. 2 and 3 corresponds to a relative setting angle β = 0 °. The adjustment range for the angle β is a maximum of 90 ° and is limited by the mechanical stop already described. Contrary to the drawing, the adjustment range for the relative adjustment angle ß, which is limited by the stop, could also be made larger or smaller than 90 °.

The particular advantage of a coaxial design as shown in FIGS. 2 and 3 is, in addition to a space-saving construction, above all the fact that when the device is operated with a small amount or even with zero amount for the relative setting angle β there is a reduction or even a complete relief of the shaft bearings from the centrifugal forces. This aspect is particularly important for applications where - such as for vibrating tables for molding machines - continuous continuous operation is provided with predominant operating mode ß = 0 °.

With a device according to FIGS. 2 and 3, one could also implement the technical teaching according to claim 6:

For example, after reaching the stops, motors 203 and 207 or 203 'and 207' could be braced against one another (for example by pressurizing line parts L2, L3). The disc parts 212 and 212 'could also be designed as meshing gears and - by ensuring that a stop limiting the relative setting angle β only takes place via the stop bolt 213' - only brace the motors 203 and 207 against one another, so that the bracing over both gear pairs would be directed to the stop. FIG. 4 shows a vibration exciter device which is constructed similarly to the device in FIG. 1 with regard to the arrangement and the mode of operation of the partial unbalance bodies and the motors, with the only difference that the motors are as 3-phase asynchronous Motors are electrically operated. Organs comparable in function have the same two end digits in the reference numerals in both figures.

Motors 403 and 404 are acted upon directly by network generator 430, while motors 407 and 408 are connected to the network with the interposition of a frequency converter 432.

The mode of operation, with the assumption simplifying the situation, that friction and other power losses can be set to zero, is as follows:

First of all, all the motors run at the same speed in the specified direction of rotation w with a relative setting angle β = 0 °, the frequency f2 being equal to the mains frequency fi. The additional torques or actuating torques MD, like the motor and generator-related slip, have an absolute value of zero.

In order to set a certain relative setting angle β, the frequency f2 is increased by 10% with respect to fi. With the now occurring slip of 5%, a motor actuating torque MDM is developed in the motors 407 and 408, which in both pairs results in an adjustment of the relative actuation angle β to a corresponding value, with the result of the adjustment develop the partial unbalance bodies 405 and 406 reaction torques MRπ which have the same amount as the motor actuating torques MDM.

The reaction torque MRi which automatically set on the partial unbalance bodies 401 and 402 drive the motors 403 and 404 beyond their synchronous speeds into generator operation with 5% generator slip, in which a generator actuating torque MDo is the same Set the amount as for motors 407 and 408.

The power fed into the network by the motors 403 and 404 has the same size as that which is fed from the network by the motors 407 and 408. drawn power (power loss assumed as zero). Both services can be viewed as apparent services.

In real, practical operation, the motors work as servomotors and working drive motors at the same time. A working torque MDA must be applied to each of the 4 shafts, which also includes the friction losses. As long as MDA <MRi on the shafts 417 and 418, the motors 403 and 404 work as generators. In the event that the motors 403 and 404 are also to be operated via a frequency converter (434), another energy rejection would have to be carried out for the generator operation. Instead, of course, there are other solutions (such as DC braking) to generate a "braking torque" on these motors.

The content of the curve diagrams of FIGS. 5 and 6 was already discussed in the course of the introduction to the description.

5 shows the unbalance body over an angle range of 2π via the angle of rotation μ:

The course of the reaction torques MR as a function of the relative setting angle β for β = 30 °, 90 ° and 180 °.

The size of the average reaction torques MR as a function of the relative setting angle ß for ß = 30 ^* and 90 ^* [MR (ß = 180 °) = 0], it should be noted that the size of the average reaction torques MR corresponds to the amount are always equal to the size of the actuating torques MD required for the setting of the corresponding relative actuating angle β.

The size of the optimal bracing torque MDVS for the case ß = 90 ^* . When dimensioning the MDVS torque in this size, it is ensured that no backlash occurs on the stop elements after the tightening torque has been applied.

The size of the angular velocity fluctuations delta w is due to the deviations of the size MR f (ß) from the actuating torque MD = f (ß) for the case ß = 90 ^* and under the condition that there are no reversing gears in the drive. 6 shows as a graph curve over the relative setting angle β:

- The course of the average reaction torque MR = f (ß). Since MR = f (ß) can always be equated with the necessary actuating torque MD = f (ß), and since the actuating torque in hydraulic motors is proportionally dependent on the hydraulic actuating pressure p ₃ , represents the same curve all 3 sizes.

The resulting centrifugal moment MR. The curve shows that at ß = 90 ^* 70.7% of the maximum possible value has already been reached.

Claims

Patent claims

1. Device for vibrating a device frame in a predeterminable direction with the features:

The device has partial unbalance bodies mounted in the frame and drivable for rotation around an assigned axis for generating partial centrifugal force vectors, of which a first and a second partial unbalance body each form a pair, the partial centrifugal moments of which can be rotated relative to one another by a relative setting angle β at least between a first position (β = 0 °) in which the resulting centrifugal moment is minimal and a second position in which the resulting centrifugal moment has reached a predetermined maximum value,

the device comprises at least 2 pairs of partial unbalance bodies,

- An actuator with actuator consisting of rotor and stator is provided for the generation of a relative rotation between the pair-forming partial unbalance bodies also during their rotation, the actuating torques MD, that being the adjusting torques or the holding torques for the adjustment or maintenance of a relative actuation angle β, for which the first and the second partial unbalance bodies are each derived from rotating motor rotors, an actuating device is provided to act upon the actuators with the actuators. Torque-determining actuating energy quantities or actuating powers, with which the relative actuating angles ß are also determined for a specific constellation of operating conditions, in combination with the following features: a) each partial unbalance body (101, 102, 105, 105 ) is assigned a separate servomotor (103, 104, 107, 108) to which it is connected in a torque-transmitting manner, b) the actuators (103, 104), (107, 108) assigned to the partial unbalance bodies of the same type (101, 102), (105, 106) transmit impressed actuating torques MD to the partial unbalance bodies at which the moments occur MD including bearing friction torques with the same ß amount, but act in different directions, in one type acting in the direction of rotation and in the other type against the direction of rotation, c) for the maximum setpoint of the resulting centrifugal torque MR, a maximum allowable size MR, max is defined, which is converted into a maximum relative setting angle βmax by the actuating device after the maximum setpoint has been entered, the size of the maximum relative setting angle βmax being fixed at values in the range of ß = 90 ° or at values below 90 ° , d) the partial unbalance bodies have partial centrifugal torques with a value which can be defined in mkg, such that the sum of the absolute values of the partial centrifugal torques of the at least 2 pairs is greater than the absolute value of the maximum permissible resulting centrifugal torque | MR, max | .

2. Apparatus according to claim 1, characterized in that a mirror-image symmetrical synchronous guidance of the angle of rotation as a sum of the rotational angle of rotation and the proportional relative actuating angle ß for at least two partial unbalance bodies of a kind (101, 102), (105, 106) in essentially by the action of inertial forces, and that the angle of rotation component for the relative angle of adjustment β is guided synchronously by the actuating torques MD, which are of equal magnitude and act on the at least two partial unbalance bodies of one type.

3. Apparatus according to claim 1 or 2, in which the equalization of the amounts of the actuating torques, which are assigned to the partial imbalance bodies of each type, is effected by specifying the same physical quantity determining the actuating torque (e.g. Pressure) to the servomotors by connecting the servomotors in parallel to the same manipulated variable generating device (112), (432, 434) by means of hydraulic or electrical lines (118), (436, 438).

4. Device according to one of claims 1 to 3, in which a limiting device (230) for the adjustment of the relative Stellwin¬ angle ß to the maximum real setting angle ßmax is provided, upon reaching which limit an intervention in the actuating torque or in the angular adjustment movement.

5. The device according to claim 4, wherein the angle adjustment movement is limited by a mechanical stop (213, 230) against which stop a clamping torque generated by the adjusting motors is effective.

6. Device for vibrating a device frame in a predeterminable direction with the features:

The device has partial unbalance bodies mounted in the frame and drivable for rotation around an assigned axis for generating partial centrifugal force vectors, of which a first and a second partial unbalance body each form a pair, the partial centrifugal moments of which can be rotated relative to one another by a relative adjustment angle β at least between a first position (β = 0 °) in which the resulting centrifugal moment is minimal and a second position in which the resulting centrifugal moment has reached a predetermined maximum value ,

the device comprises at least 2 pairs of partial unbalance bodies,

- An actuator with a rotor consisting of a rotor and a stator is provided for the generation of a relative rotation between the pair-forming partial unbalance bodies even during their rotation, the actuating torques MD, that being the adjusting torques or the holding torques for the adjustment or maintenance of a relative setting angle β, for the first and the second partial unbalance bodies, are each derived from rotating motor rotors,

- An actuating device is provided for applying actuating power to the actuating motors in combination with the following features: a) the partial unbalance bodies of the first type (101, 102) and second type (105, 106) are each at least one actuating motor (103, 107 ) assigned, the rotor of which is connected to the partial unbalance bodies in a torque-transmitting manner, b) for the maximum desired value of the resulting centrifugal torque MR which is at the end of the continuously adjustable adjustment range, a maximum permissible variable MR, Kon, max is defined, which by the control device after entering the maximum setpoint in one maximum relative setting angle ßKon.max is converted, the size of the maximum relative setting angle ßKon.max being set to values in the range of ß = 90 ° or to values below 90 °, c) the partial unbalance bodies have partial Centrifugal torques with a value definable in mkg, such that the sum of the absolute values of the partial centrifugal torques of the at least 2 pairs is greater than the absolute value of the maximum permissible resulting centrifugal torque | MR, Kon, max | , d) at the latest when the predetermined maximum relative actuating angle βmax is reached, at least for a pair of the relative actuating angles β has been limited by a mechanical stop (213 ', 230'), against which stop a clamping tension generated by the adjusting motors has been limited - Torque is effective.

7. Device according to one of claims 5 or 6, wherein the angular adjustment movement directed against the stop (213, 230) is selected such that the average reaction torques MR are directed counter to the tightening torques.

8. The device according to claim 6 or 7, wherein the tightening torques are greater than the average reaction torques MR.

9. Device according to one of the preceding claims, in which a device for positive synchronization (204, 204 ') of the rotation angle is provided at least between two partial unbalance bodies of a type of two pairs.

10. Device according to one of the preceding claims 4 to 9, in which the rotational movement of the partial unbalance body of a pair is transmitted to components arranged on an axis of rotation (214) and in that a stop angle (213, 230) limiting the relative adjusting angle β is between the ¬ sen components is made.

11. The device according to one of the preceding claims, in which the servomotors work partly as motors (407, 408) and partly as generators (403, 404) and at the same time drive motors (103, 104; 107, 108) for the rotational movement of the part unbalance bodies are.

12. Device according to one of the preceding claims, in which the servomotors or drive motors are AC motors.

13. Device not according to one of the preceding claims, in which the servomotors or drive motors of the first and second type are three-phase motors, characterized by the combination of the following features: a) Both types of three-phase motors are connected to two different three-phase systems with one parameter -Difference either with respect to the characteristic variable rotational frequency or with respect to the characteristic variable angular length of the resulting rotating field vector, b) at least one of the three-phase systems is not identical to the network-type three-phase system and is artificially generated by a control part, c) the control part Generation of the at least one artificial three-phase system has a semiconductor current path switch for each phase of the system, by means of whose pulse on / off switching a predetermined amount of energy is passed through the switch per cycle, the passage of the currents for each phase in a cyclical manner Exchange takes place, bezo In relation to the temporal maximum values of the energy quantities, d) the relative setting angle β is produced by generating a generator torque on one of the three-phase motors by inducing an oversynchronous mode of operation, the state of which is determined by the difference in the parameters, e) die The parameter difference is the sum of a first partial difference which can be measured between the first three-phase system and the rotor of the driving motor and a second partial difference which can be measured between the rotor of the braking motor and the second three-phase system.

14. The apparatus according to claim 13, characterized in that the electrical power coupled out during the generation of the generator torque, or in that the torque-determining active currents flowing backwards through the motor connection terminals when generating the generator torque in comparison to the motor operation i * are recorded in their effective variable and that this effective variable is evaluated by control technology either to determine the actual variable of the relative setting angle ß or for setting and / or keeping a predetermined relative setting angle ß.

15. The apparatus according to claim 13 or 14, characterized gekennzeich¬ net that for the setting and / or keeping a predetermined relative setting angle ß in the control influencing the Moto¬ ren the regularity of the relationship between active currents i * and Rela¬ tive setting angle ß, preferably according to the relationship "i * is proportional to sin ß", is also processed.

16. The device according to one of claims 13 to 15, characterized in that the switching elements of the control part are controlled in their switching mode by a computer, that the rotational frequency of the motors and the relative setting angle ß are simultaneously adjustable, that the setting and / or keeping constant of the relative setting angle β is brought about by a control loop, and that the control algorithm has, in addition to a proportional component, also an integral component.

17. The device according to one of claims 1 to 16, characterized ge indicates that the vibration excitation device is part of a vibrating table of a molding machine.

18. Device according to one of claims 1 or 2, in which the actuating motors are impressed with an actuating torque MD that is the same for each partial unbalance body of a pair, but different from pair to pair, so that for each pair a different relative setting angle is set.

19. Device according to one of claims 1 or 2, wherein for the adjustment of the relative setting angle ß for each pair a device ß the angle ß is provided and wherein by the action of the angle ß limiting device for each pair different relative setting angle β is set.

20. Device according to one of claims 1 to 17, wherein optionally in addition according to the characterizing parts of claims 18 or 19, a different relative setting angle ß is adjustable for each pair.