Soil compacting device and phase adjustable unbalanced vibration exciter with two driven shafts

Abstract

To provide an unbalanced vibration exciter with a simplified structure.SOLUTION: An unbalanced vibration exciter has at least two unbalanced shafts (21, 22) arranged in parallel with each other, each of the unbalanced shafts (21, 22) has its own drive device (23, 24) separately driven and controlled to generate drive torque, a coupling device (27) is provided for coupling both unbalanced shafts (21, 22) so that they can rotate in opposite directions, and the coupling device (27) has a play device (31) for allowing intentional play in the rotational positions of both unbalanced shafts (21, 22) relative to each other, the play device (31) allows play (31) between the two unbalanced shafts (21, 22) at a predefined angle, and the rotation angle is selected from a rotation angle range of 45° to 315°.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an unbalanced exciter having two axes driven in parallel to one another and to a soil compaction device using this unbalanced exciter. [Background technology]

[0002] Such types of soil compaction devices are known and are often called vibration or vibrating plates. The soil compaction device has an upper mass and a lower mass, which are connected to each other by a rubber damper, which is usually used as a vibration isolator.

[0003] In known vibration plates, a drive in the form of an internal combustion engine is provided on the upper mass, a rudder with a guide yoke can be attached to the upper mass, by means of which an operator controls the vibration plate, and an unbalanced vibrator is provided on the lower mass, which serves to generate vibrations that are introduced into the soil to be compacted via a soil contact plate also provided on the lower mass.

[0004] Particularly in the case of small and medium-sized vibration plates, the power of the drive motor is transferred by means of a belt drive to an unbalance exciter arranged in the lower mass. Furthermore, a centrifugal clutch can be flanged to the internal combustion engine used as the drive motor, so that the unbalance exciter is still decoupled from the motor at low motor speeds.

[0005] The unbalanced exciter itself often comprises two counter-rotatable parallel shafts, each supporting an eccentrically positioned weight (unbalanced mass) that, when rotated, induces the desired vibration.

[0006] By changing the phase position of the unbalanced axes relative to one another, and in particular by changing the angular position of the unbalanced axes and thus the respective unbalanced masses relative to one another, the direction of the resulting force vector can be changed. In this way, reversibility of the vibration plate is obtained, so that the vibration plate can be made to travel forward and backward. Furthermore, stationary vibration can also be achieved.

[0007] Examples of unbalanced vibration exciters constructed in this way can be found in DE 2 409 417 A1 and DE 3 043 719 A1.

[0008] German Patent Application DE 10 2020102 949 A1 further discloses an unbalanced vibration exciter in which an electric motor for driving the unbalanced vibration exciter is provided in the lower mass and is integrated in the unbalanced vibration exciter.

[0009] This unbalanced exciter also allows for direction changes. In this case, one of the unbalanced shafts is driven by an electric motor, while the second unbalanced shaft is driven in the opposite direction via a spur gear toothing. In this case, one of the spur gears is rotated by approximately 180° with respect to its unbalanced shaft. For this purpose, a helical or pivot groove is provided. The relative adjustment takes place via a hydraulically axially operated, rotationally decoupled piston, which holds a switching pin, which in turn engages in the pivot groove. The hydraulic pressure required for the switching process is generated by the piston with a rack, the gear shaft and the switching yoke, for example in a master cylinder provided on the guide rod. In the case of a vibration plate with a hydraulic drive, this hydraulic pressure can also be provided by an on-board hydraulic system.

[0010] For the above-mentioned phasing of the unbalanced exciter, which is necessary in particular for the direction switching or reversibility of the vibration plate, numerous relatively expensive components are required, such as, for example, a rudder head with a master cylinder, a gear shaft, a master piston with a rack, sealing elements, hydraulic hoses, an adjustment cylinder, an adjustment piston, a rotary decoupling, a piston with a switching pin, and an adjustment sleeve with a pivot groove. Furthermore, the hydraulic machines required for the phasing are susceptible to contamination, for example by chips. Summary of the Invention [Problem to be solved by the invention]

[0011] The problem underlying the present invention is to provide an unbalanced exciter which has a simplified structure but nevertheless provides the same functionality as an unbalanced exciter of more complex structure. [Means for solving the problem]

[0012] This problem is solved according to the invention by an unbalanced vibration exciter with the features of claim 1. Advantageously, the unbalanced vibration exciter can be used in a soil compaction device as set out in the parallel claims. Advantageous configurations are defined in the dependent claims.

[0013] An unbalanced vibration exciter is presented, which has at least two unbalanced shafts arranged parallel to each other, each of the unbalanced shafts having its own separately drive-controllable drive device for generating a drive torque, a coupling device is provided for coupling both unbalanced shafts in a manner that allows them to rotate in opposite directions to each other, and the coupling device has a play device for allowing intentional play in the rotational positions of both unbalanced shafts relative to each other.

[0014] By means of such a play device, for example, a play between both unbalanced shafts can be made possible with a predefined rotation angle, which is selected from the rotation angle range of 45° to 315°, as will be explained in more detail below and by way of further examples.

[0015] The unbalanced shaft has a shaft section on which one or more unbalanced masses are arranged. For example, an unbalanced mass may be arranged on an unbalanced shaft which is fixedly mounted on the unbalanced shaft and which may consist of several partial unbalanced masses. It is therefore also possible to distribute the (total) unbalanced mass over the length of the unbalanced shaft in the form of several partial unbalanced masses. For example, partial unbalanced masses can be attached to both end faces of the unbalanced shaft, respectively. The unbalanced shafts are rotatably supported in one common exciter housing.

[0016] An example of such an unbalanced shaft is shown, for example, in DE 102020102949 A1. It is also shown in this document that the unbalanced shaft can be driven by an electric motor which is directly integrated in the unbalanced shaft. However, in DE 102020102949 A1, only one of the two unbalanced shafts is driven by an electric motor, whereas the other, second unbalanced shaft, is connected by a coupling device and is driven together, while on the other hand, according to the invention, both unbalanced shafts are provided with their own drive. The drive can likewise be integrated in the respective unbalanced shaft in the form of an electric motor. It is likewise possible for both drives to be provided separately from the unbalanced shaft, but a suitable torque transmission device (e.g. belt drive or hydraulic) must be provided.

[0017] Thus, each unbalanced shaft has its own drive which can be controlled separately.

[0018] The coupling device allows for a mechanically counter-rotatable, e.g. positively-locking counter-rotatable coupling of the two unbalanced shafts, where "coupling" in this context means that the rotations of the unbalanced shafts are coupled to one another while maintaining respectively set phase positions.

[0019] However, a rigid, for example form-locking, connection is eliminated or released within a fixedly defined range by the play device, which thus allows for deliberate (rotational) play with regard to the rotational position of the unbalanced shafts and thus their phase positions relative to one another. The unbalanced shafts are free to rotate relative to one another within this play, i.e. within a predefined rotation angle range.

[0020] This predefined intentional play in rotational position allows a change in the phase position of both unbalanced shafts relative to each other.

[0021] The deliberate play in the rotational position means, in particular, that two extreme rotational positions of the unbalanced shaft relative to one another are made possible. These extreme rotational positions can be defined, for example, by two stops. Depending on the direction of rotation or the flow direction of the drive torque between the two unbalanced shafts, the unbalanced shafts take up one or the other extreme position relative to one another and thus one or the other phase position relative to one another. Thus, depending on the flow direction of the drive torque, a predefined phase position can be set, taking advantage of the play.

[0022] The play device, provided as a component part of the coupling device, makes it possible to define two extreme or relative positions of the phase positions of both unbalanced shafts coupled by the coupling device. Depending on which extreme position is occupied at the end of the play, both unbalanced shafts are in predefined phase positions relative to each other. The phase positions likewise determine the direction of the force vector (resulting force vector) resulting from the rotating unbalanced mass on the unbalanced shaft. The rotational positions allowed by the play device can be selected such that the resulting force vector is selectively suitable for forward or reverse travel.

[0023] The permissible extreme rotation positions are limited by a defined rotation angle range between 45° and 315°. This rotation angle range indicates a total angle range which may possibly result from several, in particular partial rotation angles (with respect to two unbalanced axes). The play allowed by the play device may thus be possible in a (total) rotation angle range of 0° to 720°, in particular 90° to 720°, in particular 90° to 270° as well as 450° to 720°, in particular 45° to 315°, in particular 90° to 270°, in particular 120° to 240°, in particular 150° to 210°, in particular 175° to 185°. The rotation angle range which has been proven in practice and is therefore preferred is ±90°, i.e. in total (total rotation angle range) approximately 180°.

[0024] A total rotation angle range of 720° means that the phase positions of both unbalanced shafts can each be rotated by 360° relative to the other unbalanced shaft.

[0025] The play device can provide two rotation stops for defining the extreme positions of the rotation angle allowed by the play relative to the unbalanced shafts, so that both end positions or rotation stops define two extreme positions to which both unbalanced shafts can be rotated relative to each other corresponding to two defined different phase positions.

[0026] Both rotation stops can also be realized by several partial rotation stops one after the other, which allow respective partial rotation angles which together correspond to a predefined total rotation angle.

[0027] The two drives can be controlled in such a way that they, and thus the unbalanced shafts driven by them, can rotate counter to one another, i.e. in opposite directions of rotation.

[0028] The two drives are alternately controllable so that one of the drives generates a stronger drive torque than the other, and depending on which drive currently generates the stronger drive torque, one of the two limit positions defined by the respective rotation stops of the two unbalanced shafts relative to each other is set. The drive torque flows from the stronger drive and the unbalanced shaft driven by the stronger drive via the coupling to the weaker driven unbalanced shaft or to the weaker drive.

[0029] Thus, both drives can be operated simultaneously, one of the drives generating a stronger drive torque than the other in order to achieve a defined relative position of both unbalanced shafts relative to one another and thus a defined phase position. In this case, it is also possible for only one of the drives to be driven, while the other drive is not driven or braked and thus does not generate a drive torque. This not driven or braked drive is then driven together with the unbalanced shaft assigned to it by the driven drive. Braking of the drive can also be performed, for example, intentionally, by operating the drive to generate electricity, i.e. as a generator.

[0030] When a drive with a stronger drive torque is replaced and the flow direction of the drive torque is changed accordingly, a rotation of the two unbalanced shafts relative to one another, which is enabled by the idler device, can be automatically brought about and thus another phase position can be set. The phase position is thus set as a function of the direction of rotation of the drives or the flow direction of the drive torque of both drives. This also applies when one of the two drives is not driven or is braked, so that it does not generate a drive torque.

[0031] Thus, operating states are possible in which one of the drives is activated while the other drive is not activated or is activated with a lower power, and it is therefore desirable for the activated drive, in particular the drive activated with full drive power, to drag or drag along the non-activated or weaker drive.

[0032] Each of the unbalanced shafts may have an individually controllable electric motor as drive, which may have a rotor that may be a component of the associated unbalanced shaft, in which case the rotor may in particular be formed directly on the unbalanced shaft, whereas the associated stator may be accommodated in the exciter housing.

[0033] An operating state "forward travel" may be provided, in which one of the unbalanced shafts is a first unbalanced shaft and the other unbalanced shaft is a second unbalanced shaft, the first unbalanced shaft is driven by a drive device assigned to it, the second unbalanced shaft is not driven or is driven less strongly than the first unbalanced shaft by a drive device assigned to it, and when the first unbalanced shaft is driven, the play in the play device is overcome and the second unbalanced shaft is dragged around by the coupling device. Overcoming the play is understood in this case to mean that in each case one of the rotation stops acts and thus both unbalanced shafts take up a defined phase position relative to each other.

[0034] As an alternative to the operating state "forward travel", an operating state "reverse travel" can be provided, in which the second unbalanced shaft is driven by a drive device arranged corresponding to the second unbalanced shaft, the first unbalanced shaft is not driven or is driven less strongly than the second unbalanced shaft by a drive device arranged corresponding to the first unbalanced shaft, and when the second unbalanced shaft is driven, the play in the idle device is overcome and the first unbalanced mass is dragged around by the coupling device.

[0035] Furthermore, an operating state "stationary vibration" may be provided, in which repeated switching between the operating states "forward travel" and "reverse travel" occurs, with the periods during which the operating states "forward travel" and "reverse travel" are activated respectively being equal but each shorter than 5 seconds. The operating state "stationary vibration" allows point compaction by the vibration plate with the unbalanced exciter, i.e. compaction in situ without the vibration plate moving forward or backward.

[0036] The operating state "stationary vibration" is achieved by quickly switching between forward and reverse travel, i.e. before the vibration plate can travel in the corresponding direction. Since the vibration plate has a large inertial mass, it usually needs some time to move, even if the resulting force vector is already pointing in one direction. Therefore, the direction of travel is changed by switching the operating state from forward to reverse travel or vice versa in the unbalanced exciter before the vibration plate can start traveling, which results in the vibration plate remaining stationary. The time period for switching between forward and reverse travel is preferably selected such that the respective rotation stop reaches its defined extreme position.

[0037] The period presented as a maximum of 5 seconds may be too long in some embodiments. This period may therefore be less than 4 seconds, less than 3 seconds, less than 2 seconds or less than 1 second. For example, both drives of the unbalanced shaft can be driven alternately every 2 seconds, which causes a switch between forward and reverse running and thus achieves stationary vibration.

[0038] Additionally or alternatively, an operating state "slow travel" can be provided, in which repeated switching between the operating states "forward travel" and "reverse travel" occurs, with the periods during which the operating states "forward travel" and "reverse travel" are activated respectively depending on the desired direction of travel being different from each other and shorter than 8 seconds, for example shorter than 5 seconds or 3 seconds. In this operating state, the operating state of the above-mentioned "stationary oscillation" is thus changed. Here too, a regular and relatively rapid switching between forward travel and reverse travel occurs. However, whereas in the stationary oscillation the respective periods for forward travel and reverse travel are identical, for the operating state "slow travel" these periods differ from each other. For example, for slow forward travel it is provided that the periods for forward travel are somewhat longer than the periods for reverse travel. This achieves that the resulting force vector for forward travel acts somewhat longer than the force vector for reverse travel, as a result of which - due to the high mass inertia of the vibration plate - a slower forward travel is achieved.

[0039] For example, for slow forward driving, a period of 3 seconds in the forward direction and 2 seconds in the reverse direction can be set.

[0040] The definitions of "first unbalanced shaft" and "second unbalanced shaft" presented above are arbitrary. Thus, for example, the unbalanced shaft that is driven in the driving state "forward driving" can always be defined as the "first unbalanced shaft". The second unbalanced shaft is therefore another unbalanced shaft or an unbalanced shaft that is driven in the driving state "reverse driving".

[0041] Both unbalanced shafts may each carry a gear, which are arranged in mesh with one another, one or both of the gears being rotatable with respect to the unbalanced shaft carrying the gear respectively, over an angular range defined by a rotation stop. The gears may be part of a coupling device, and are capable of transmitting a drive torque from one unbalanced shaft to the other. Due to the relative rotatability of both gears (or just one gear) with respect to the correspondingly arranged unbalanced shaft, various phase positions can be set. Therefore, a rotation stop is provided which defines the relative rotation of both gears (or one gear).

[0042] The idler device may have two rotation stops on one of the unbalanced shafts, which are rotated relative to one another by an angle corresponding to a predefined rotation angle range. Both rotation stops thus form end stops for two predefined phase positions of the unbalanced shaft. For example, the rotation stops may be rotated relative to one another by an angle of about 180°.

[0043] In one variant, the idler device may have two rotation stops on both unbalanced shafts, which rotate relative to each other by a partial rotation angle, the sum of the partial rotation angles corresponding to a predefined rotation angle range. In this case, the stops are distributed on both unbalanced shafts. For example, both gears of the coupling device may rotate relative to the unbalanced shaft that supports them.

[0044] The coupling device may have two meshing gears, each arranged on one of the unbalanced shafts, one of the gears being a first gear fixedly arranged on the first unbalanced shaft and the other of the gears being a second gear arranged on a second unbalanced shaft and supported rotatably relative to said second unbalanced shaft, and the idler device has a follower which is inserted into the second unbalanced shaft and both rotation stops are provided on the second gear, the follower abutting against one of the rotation stops depending on the flow direction of the drive torque between the two gears.

[0045] Thus, in this variant, one of the gears is fixedly arranged on the (first) unbalanced shaft, whereas the gear on the second unbalanced shaft is rotatable within a rotation angle range.

[0046] The entrainer can be formed, for example, by a pin.

[0047] In one variant, the coupling device can have two meshing gears, each arranged on one of the unbalanced shafts, both gears arranged rotatably on the unbalanced shaft that supports them, a driver is inserted in each of the two unbalanced shafts, two rotation stops are provided on each of the two gears, and both driver bodies rest against one of the rotation stops that are respectively assigned to the driver bodies depending on the flow direction of the drive torque between the two gears. Here too, the driver bodies can each be designed, for example, as a pin or a bolt.

[0048] In this alternative variant, both gears are rotatable about the unbalance axis associated with them, in particular by a predetermined partial rotation angle, so that the sum of the partial rotation angles (e.g. 90° each) amounts to a predefined total rotation angle (e.g. 180°).

[0049] In this last-mentioned variant, it is possible to design both unbalanced shafts and both drives identically. This also applies to the coupling and idler devices, i.e. the gears, the rotary stops and the drivers (e.g. pins). In this way, a large number of identical parts can be used. The complete unbalanced shafts can be completely identical and can be integrated into the exciter housing.

[0050] The described unbalanced vibration exciter can be used particularly advantageously in soil compaction devices, such as vibration or vibration plates.Therefore, a soil compaction device is also presented, which comprises an upper mass, a lower mass movable relative to the upper mass, a soil contact plate for concrete compaction, a vibration isolating device acting between the upper and lower masses, and at least one unbalanced vibration exciter belonging to the lower mass for loading the soil contact plate with an unbalanced force, the unbalanced vibration exciter being an unbalanced vibration exciter of the above-mentioned type.

[0051] These and other advantages and features will now be explained in more detail by way of example with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0052] [Figure 1] FIG. 2 is a side view showing the soil compaction device according to the present invention. [Diagram 2] FIG. 2 is a partial perspective view of the unbalanced vibration exciter as seen from above in section. [Diagram 3] FIG. 3 is a diagram showing a modification of the unbalanced vibration exciter shown in FIG. [Figure 4] FIG. 13 shows an example for the positions of the coupling device and the idler device in the driving state "forward travel". [Diagram 5] FIG. 13 shows an example for the position of the coupling device and the idler device in the driving state "reverse travel" at the time of switching. [Figure 6]FIG. 6 is a diagram showing the operating state shown in FIG. 5 at a point in time after the unbalanced shaft has rotated 90°. [Figure 7] FIG. 5 is a diagram showing a modification to FIG. 4, illustrating an example of the positions of the coupling device and the idler device in the driving state "forward travel". [Figure 8] FIG. 8 is a diagram showing an example of the positions of the coupling device and the play device in the driving state "reverse travel" at the time of switching in the modified example shown in FIG. 7. [Figure 9] FIG. 9 is a diagram showing the operating state shown in FIG. 8 at a point in time after the unbalanced shaft has rotated 270°. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] FIG. 1 shows an example of a vibration plate acting as a soil compaction device.

[0054] The vibration plate has an upper mass 1 and a lower mass 2 that is movable relative to the upper mass 1. The lower mass 2 is connected to the upper mass 1 via a rubber damper 3 that acts as a vibration isolator. In this way, strong vibrations occurring in the lower mass 2 are simply damped and transmitted to the upper mass 1.

[0055] The upper mass 1 has a support frame 4 on which an accumulator 5 and a converter 6 are mounted. The accumulator 5 and the converter 6 are also grouped into the upper mass 1. The accumulator 5 and the converter 6 are surrounded by a protective frame 7.

[0056] The accumulator battery 5 is exchangeable and can be replaced by another accumulator battery if necessary. For this purpose, the converter 6 or a converter casing belonging to the converter 6 is provided with a connector into which the accumulator battery 5 can be plugged.

[0057] The lower mass 2 has a soil contact plate 9 by means of which the soil lying below can be compacted. On the upper side of the soil contact plate 9 a vibration generator or unbalanced exciter 10, which also belongs to the lower mass 2, is arranged.

[0058] In the prior art, such unbalanced exciters are often driven in rotation by a prime mover, in particular an internal combustion engine arranged in the upper mass, but according to the invention, as will be explained further below, two electric motors, not shown in Figure 1, are integrated directly into the unbalanced exciter 10.

[0059] A guide rod 11 is furthermore attached to the upper mass 1 or to the support frame 4 for guiding the vibration plate. The guide rod 11 may be provided with a speed lever (not shown) for influencing the motor speed of the electric motor acting as the drive motor. However, depending on the embodiment, an on / off switch for switching on the electric motor, which will be explained further below, is also sufficient.

[0060] At the upper end of the guide rod 11, a guide yoke or control grip 12 is arranged, by means of which the relative rotational positions of the unbalanced shafts in the unbalanced exciter 10, in particular their phase positions relative to one another, can be adjusted, as will be explained further below. In this way, forward and reverse travel of the vibration plate can be achieved in a manner known per se.

[0061] The lower mass 2 or soil contact plate 9 is provided with a wheel arrangement having two axially opposed wheels 13. In the normal state shown in Figure 1, the wheels 13 float above the soil. However, by tilting the vibration plate, the wheels 13 can be brought into contact with the soil, so that the soil contact plate 9 is completely lifted off the soil. In this tilted or transport state, the vibration plate can be easily moved and transported by the wheels 13.

[0062] The unbalanced exciter 10 has an exciter housing 20 which, as shown in FIG. 1, is mounted directly on the soil contact plate 9, so that the vibrations generated by the unbalanced exciter 10 can be optimally introduced into the soil contact plate 9 and thus into the soil to be compacted.

[0063] FIG. 2 shows a cutaway plan view of the unbalanced exciter 10.

[0064] Two unbalanced shafts, i.e., a first unbalanced shaft 21 and a second unbalanced shaft 22, are rotatably supported inside the vibration exciter housing 20. The first unbalanced shaft 21 can be driven by a first electric motor 23 (M1), and the second unbalanced shaft 22 can be driven by a second electric motor 24 (M2).

[0065] The two unbalanced shafts 21, 22 are connected so that they can rotate in opposite directions. For this purpose, a gear pair is provided, which comprises a first gear 25 mounted on the first unbalanced shaft 21 and a second gear 26 mounted on the second unbalanced shaft 22. The two gears 25, 26 together form part of a coupling device 27 and mesh with each other, as also shown in perspective in the right-hand part of FIG. 2. In this way, depending on which of the two unbalanced shafts 21, 22 is driven, the rotation of one unbalanced shaft is directly converted into the opposite rotation of the other unbalanced shaft.

[0066] The first unbalanced shaft 21 supports a first unbalanced mass 28, which is divided into two partial mass elements 28a, 28b. Both partial mass elements 28a, 28b are spaced apart from each other in the axial direction and are arranged at the end face side of the first unbalanced shaft 21. The second unbalanced shaft 22 itself supports a second unbalanced mass 29 formed by partial mass elements 29a, 29b.

[0067] Both unbalanced shafts 21, 22 are supported on rolling bearings. All four shaft ends are fitted with unbalanced masses 28, 29. Gears 25, 26 are arranged between the rolling bearings and the respective unbalanced masses 28, 29. The mechanical connection of both unbalanced shafts 21, 22 has a large play, so that when one of the shafts is restrained, the other can rotate by approximately ±90°, as will be explained further below.

[0068] In the central region of both unbalanced shafts 21, 22, respectively, two electric motors 23, 24 are arranged. Both electric motors 23, 24 can be controlled individually and can alternately act as drive motors. For example, it is possible to operate only one of the electric motors 23, 24 while the other electric motor 23, 24 is co-rotated. Likewise, it is possible to operate both electric motors 23, 24, and it is preferable that one of the electric motors 23, 24 provides a lower drive torque than the other electric motor, depending on the desired phase position, as will be explained further below. The directions of rotation of both electric motors 23, 24 are opposite, as represented by arrow A (for the first unbalanced shaft 21 or the first electric motor 23) and arrow B (for the second unbalanced shaft 22 or the second electric motor 24).

[0069] The electric motors 23, 24 can be integrated into the unbalanced shafts 21, 22 which support them. In particular, it is possible for the electric motors 23, 24 to each have a rotor which is directly mounted on the associated unbalanced shaft 21, 22. For this purpose, a corresponding rotor seat is provided on the respective unbalanced shaft 21, 22. Accordingly, the respective unbalanced shaft 21, 22 also serves as the motor shaft of the electric motor 23, 24.

[0070] An example for a rotor is shown generally by reference numeral 30 in FIG. 3, which will be described later.

[0071] The rotors are likewise surrounded by stators, each belonging to the respective electric motor 23, 24, which are appropriately supported in the exciter housing 20. However, the electric motors 23, 24 can also be inserted into the exciter housing 20 as a complete unit. The exciter housing 20 thus supports the stators of both electric motors 23, 24 as well as the rolling bearings of the unbalanced shafts 21, 22. It is therefore advantageous if the electric motors 23, 24 are completely integrated into the unbalanced exciter 10. An external drive of the unbalanced exciter 10, as variously known from the prior art, is therefore not necessary. The unbalanced exciter 10 forms an integrated unit together with the two integrated electric motors 23, 24 and does not require a separate external drive.

[0072] Both electric motors 23, 24 are shown purely by way of example. Likewise, a solution is possible in which the electric motors are arranged outside the exciter housing 20. Likewise, hydraulic motors can be used. The motors can be attached externally to the exciter and to the outside of the unbalance body.

[0073] The first gear 25 is non-rotatably mounted on the first unbalanced shaft 21, for example by a suitable shaft-hub connection, for example by a keyed or press fit.

[0074] In the perspective, partially enlarged view shown in the right-hand portion of FIG.

[0075] The second gear 26, which meshes with the first gear 25 and can therefore rotate in the opposite direction, is held on the second unbalanced shaft 22. In this case, a play device 31 is provided, which allows a play defined in the form of a relative rotational movement of the second gear 26 with respect to the second unbalanced shaft 22, which supports the gear 26. The play device 31 has a bolt or pin 32, which acts as a driver and is accommodated vertically in the second unbalanced shaft, and which can selectively abut against the stops 33a and 33b. The second gear 26 is thus rotatably supported on the second unbalanced shaft 22, the rotational movement being limited by the cooperation of the pin 32 with the two stops 33a, 33b.

[0076] Furthermore, the pin 32, together with the unbalanced mass 29 arranged behind it, simultaneously acts as an axial position fixing part for the rotatable second gear 26 arranged between the pin 32 and the unbalanced mass 29.

[0077] In the illustrated example, both stoppers 33a, 33b are configured so that the second gear 26 can rotate by 180° with respect to the second unbalanced shaft 22 depending on the direction of action of the driving torque.

[0078] 2 with directions of rotation A and B, and assuming that the first electric motor 23 is driven exclusively while the second electric motor 24 is switched off, the first gear 25 drives the second gear 26 in the direction of the arrow A in the direction of the arrow B. Since the second electric motor 24 is switched off, it creates a friction or drag moment and is braked. The second gear 26 therefore drives the second unbalanced shaft 22 in the same direction of rotation B via the stopper 33a and the pin 32.

[0079] In the reverse situation, not shown in Fig. 2, the second electric motor 24 is driven alone, whereas the first electric motor 23 is switched off. In this case, the second unbalanced shaft 22 rotates in a driving manner in the direction of the arrow B, so that the pin 32 pivots downwards by 180° with the aid of play, until it abuts against the stop 33b. The pin 32 then drives the second gear 26 in the direction of rotation B as well, after which the first gear 25 rotates together with the first unbalanced shaft 21 in the direction of the arrow A.

[0080] The free, i.e. uncoupled, pivoting caused by play of the second unbalanced shaft 22 by 180° relative to the first unbalanced shaft 21, which remains stationary during the pivoting process, results in a different relative position of the unbalanced mass 29 supported by the second unbalanced shaft 22 and thus a different phase position relative to the unbalanced mass 28 of the first unbalanced shaft 21. The resulting changed direction of action of the forces is as will be explained below with reference to Figures 4 to 6.

[0081] The play device 31 with the pin 32 and the stops 33a, 33b is merely an example. Other solutions are also conceivable for the realization of the play device 31, for example steps and stop surfaces which are arranged directly on the respective unbalanced shaft.

[0082] Figure 3 shows a modified example of the unbalanced exciter shown in Figure 2. Reference is made to the reference symbols in Figure 2.

[0083] Unlike the embodiment shown in FIG. 2, in the variant shown in FIG. 3 both gears 25, 26 are rotatable relative to the unbalanced shafts 21, 22 which respectively support them through a defined angular range, namely 90° each.

[0084] Whereas in the variant shown in Fig. 2 the play device 31 is arranged exclusively on one of the unbalanced shafts (the second unbalanced shaft 22 in the illustrated example) and allows play over a defined total rotation angle, in the variant shown in Fig. 3 the play device 31 extends over both unbalanced shafts 21, 22, as can be seen in the enlarged perspective view in the right-hand part of Fig. 3. In particular, the first unbalanced shaft 21 is provided with a first play device 31a with a pin 32a, and the second unbalanced shaft 22 is provided with a second play device 31b with a pin 32b. Furthermore, as in the variant shown in Fig. 2, stoppers 33a, 33b are provided on the second unbalanced shaft 22 and stoppers 34a, 34b on the first unbalanced shaft 21.

[0085] 2, the stopper faces 33a, 33b are offset by an angle that allows a rotation angle of 180° of the second gear 26 with respect to the unbalanced shaft 22, whereas in the variant shown in Fig. 3, the stopper faces 33a, 33b, 34a, 34b are configured to allow a relative rotation angle of 90° of both gears 25, 26 with respect to the unbalanced shafts 21, 22 that support these gears 25, 26. However, overall, a total rotation angle of 180° occurs, as in Fig. 2.

[0086] With regard to the force vectors occurring during rotation of the unbalanced shafts 21, 22, the variants shown in Figures 2 and 3 do not differ. However, in the variant shown in Figure 3, both unbalanced shafts 21, 22 can be constructed as one and the same part, including the different components used, which further reduces the number of components to be used.

[0087] If the first unbalanced shaft 21 is driven to rotate in the direction of the arrow A via the first electric motor 23 provided on this first unbalanced shaft 21, while the second electric motor 24 provided on the second unbalanced shaft 22 is not activated or is only weakly activated, the pin 32a is pressed against the stopper surface of the stopper 34a, which causes the gear 25 to rotate in the direction of the arrow A and the second gear 26 to rotate in the direction of the arrow B. The second gear 26 entrains the pin 32b via its stopper 33a and thus drags the second unbalanced shaft 22 with the second electric motor 24.

[0088] FIG. 4 shows in a schematic diagram both gears 25, 26 as well as the unbalanced masses 28, 29 located behind them, which are shown simply in dashed lines.

[0089] The phase positions are shown for forward travel in a forward travel direction V as indicated by the arrow. The first unbalanced shaft 21 is driven in a rotation direction A. By the action of these rotating unbalanced masses 28 a force vector F1 is generated.

[0090] The situation already described above is illustrated on the basis of FIG. 2. The second gear 26 thus rotates together with the second unbalanced mass 29 in the direction of the arrow B. This rotational effect generates a centrifugal force F2. The two centrifugal forces F1, F2 are superimposed and generate a resultant force, not shown in FIG. 4, directed in the same direction. The resulting force has a vertical vibrating component, which is used for soil compaction, and a horizontal component, which in this case is directed in the travel direction V. In this way, the vibration plate utilizing the unbalanced exciter can be made to travel in the forward direction V.

[0091] FIG. 5 shows the moment of changeover from forward to reverse travel starting from the situation in FIG. 4. To reach the changeover point, the first electric motor 23 is switched off, so that the first unbalanced shaft 21 is no longer driven. Instead, the second electric motor 24 is activated and the second unbalanced shaft 22 is driven in the direction of the arrow B. As a result, the pin 32 rotates by 180° depending on the arrangement of the stops 33a, 33b, thereby reaching the position shown in FIG. 5. In this situation, the pin 32 comes into contact with the stop 33b and starts to rotate the second gear 26 in the direction of the arrow B. The second unbalanced mass 29 connected to the second gear 26 generates an unbalanced force F2 directed in the reverse travel direction R.

[0092] In this situation, the first unbalanced shaft 21 is still positioned unchanged and does not move, in particular does not rotate, compared to the situation shown in figure 4. This rotation will only take place if the now driven second unbalanced shaft 22 rotates further.

[0093] 6 shows a situation in which, starting from the situation shown in FIG. 5, both unbalanced shafts 21, 22, and thus the gears 25, 26 and the unbalanced masses 28, 29 have rotated by 90° in their respective rotational directions A, B. In this case, it can be seen that reverse running can be achieved, since the force vectors F1, F2 are directed in the reverse direction R. To continue reverse running, the second electric motor 24, and thus the second unbalanced shaft 22, continues to rotate in the rotational direction B, whereas the first unbalanced shaft 21 is rotated in the rotational direction A together with the first electric motor 23.

[0094] Figures 7 to 9 show a modified example of the unbalanced vibration exciter shown in Figures 4 to 6. In the modified example shown in Figures 4 to 6, in the case of stationary vibration, the complete centrifugal force of the exciter or the vibration plate supporting the exciter does not act, whereas in the unbalanced vibration exciter of Figures 7 to 9, a strong vertical force that vibrates can be additionally generated in the operating state of stationary vibration.

[0095] The structure of both variants is substantially identical.

[0096] However, unlike FIG. 4, in FIG. 7, which also shows the operating state "forward travel", the second unbalanced shaft 22 is driven and the second unbalanced mass 29 is structurally rotated by 180° with respect to the unbalanced shaft 22, as a comparison of both figures shows. The first unbalanced shaft 21 is dragged along in this state. Both centrifugal forces F1, F2 are identical to the variant shown in FIG. 4.

[0097] The definitions of "first unbalanced shaft" and "second unbalanced shaft" are arbitrary and have been chosen in the illustrated example to allow a better comparison of both variants. Thus, simply, the unbalanced shaft that is driven in the operating state "forward travel" can always be defined as the "first unbalanced shaft". The second unbalanced shaft can be another unbalanced shaft or an unbalanced shaft that is driven in the operating state "reverse travel".

[0098] Figure 8 shows the moment of changeover from forward to reverse travel starting from the situation shown in Figure 7 and thus similar to Figure 5. The second unbalanced shaft 22 is no longer driven, since the second electric motor 24 is now switched off. Instead, the first electric motor 23 is activated and drives the first unbalanced shaft 21 in the direction of the arrow A. As a result, the pin 32 on the second unbalanced shaft 22 rotates relative to the stops 33a, 33b.

[0099] 9 shows a situation in which, starting from the situation shown in FIG. 8, both unbalanced shafts 21, 22, and thus the gears 25, 26 and the unbalanced masses 25, 26, have been rotated by 270° in their respective rotational directions A, B. It can be seen that reverse travel can be achieved, since the force vectors F1, F2 point in the reverse direction R. To continue reverse travel, the first electric motor 23, and thus the first unbalanced shaft 21, continues to be rotated in the rotational direction A, whereas the second unbalanced shaft 22 is pulled around in the rotational direction B together with the second electric motor 24.

Claims

1. An unbalanced vibration exciter having at least two unbalanced shafts (21, 22) arranged parallel to each other, - each of the unbalanced shafts (21, 22) has its own, separately controllable drive (23, 24) for generating a drive torque; - a coupling device (27) is provided for coupling both said unbalanced shafts (21, 22) in a counter-rotatable manner, and an unbalanced exciter, in which the coupling device (27) comprises a play device (31) for allowing deliberate play in the rotational position of both unbalanced shafts (21, 22) relative to one another.

2. 2. An unbalanced vibration exciter according to claim 1, wherein the play device (31) provides at least two rotation stops (33a, 33b) for defining the extreme positions of the rotation angle allowed by the play.

3. Both drives (23, 24) are alternately controllable such that one of the drives generates a stronger drive moment than the other drive, 3. The unbalanced exciter according to claim 1, wherein one of the two limit positions defined by the respective rotation stops of the two unbalanced shafts (21, 22) relative to each other is set depending on which drive device is currently generating a stronger drive torque.

4. An operating state "forward driving" is provided, and in the operating state "forward driving", one of the unbalanced shafts is a first unbalanced shaft (21) and the other unbalanced shaft is a second unbalanced shaft (22), the first unbalanced shaft (21) is driven by the drive device (23) arranged corresponding to the first unbalanced shaft (21), the second unbalanced shaft (22) is not driven or is driven less strongly than the first unbalanced shaft (21) by the drive device (24) arranged corresponding to the second unbalanced shaft (22); and The unbalanced exciter according to any one of claims 1 to 3, characterized in that when the first unbalanced shaft (21) is driven, the play in the play device (31) is overcome and the second unbalanced shaft (22) is entrained by the coupling device (27).

5. An operating state "reverse driving" is provided, and in the operating state "reverse driving", the second unbalanced shaft (22) is driven by the drive device (24) arranged corresponding to the second unbalanced shaft (22), and the first unbalanced shaft (21) is not driven or is driven less strongly than the second unbalanced shaft (22) by the drive device (23) arranged corresponding to the first unbalanced shaft (21); and 5. The unbalanced vibration exciter according to claim 1, wherein when the second unbalanced shaft (22) is driven, the play in the play device (31) is overcome and the first unbalanced shaft (21) is rotated by the coupling device (27).

6. - an operating state "stationary vibration" is provided, in which the operating state "stationary vibration" is repeatedly switched between the operating state "forward travel" and the operating state "reverse travel", and An unbalanced exciter according to claim 5, dependent on claim 4, in which the periods during which the operating states "forward travel" and "reverse travel" are activated are identical but each shorter than 5 seconds.

7. - a driving state "slow driving" is provided, in which the driving state "slow driving" is repeatedly switched between the driving state "forward driving" and the driving state "reverse driving", and The unbalanced exciter according to claim 5, dependent on claim 4, wherein the periods during which the driving states "forward travel" and "reverse travel" are activated differ from one another depending on the desired direction of travel, but are each shorter than 8 seconds.

8. - both unbalanced shafts (21, 22) support gears (25, 26) respectively, - said gears (25, 26) are arranged in mesh with one another, and An unbalanced exciter according to any one of claims 1 to 7, characterized in that one or both of the gears (25, 26) are rotatable over an angular range determined by rotation stops (33a, 33b) relative to the unbalanced shafts (21, 22) which respectively support the gears (25, 26).

9. 9. The unbalanced exciter according to claim 1, wherein the idler device (31) has two rotation stops (33a, 33b) on one of the unbalanced shafts (22), which are rotated relative to one another by an angle which corresponds to the predefined angular range.

10. the idler device (31) has two rotation stops (33a, 33b, 34a, 34b) on each of the two unbalanced shafts (21, 22), the rotation stops (33a, 33b, 34a, 34b) being rotated relative to one another by a partial rotation angle, 10. The unbalanced exciter according to claim 1, wherein the sum of the partial rotation angles corresponds to the predefined rotation angle range.

11. the coupling device (27) comprises two gears (25, 26) which mesh with each other, each gear (25, 26) being arranged on one of the unbalanced shafts (21, 22); one of said gears is a first gear (25) fixedly arranged on said first unbalanced shaft (21); the other of said gears is a second gear (26) arranged on said second unbalanced shaft (22) and journalled so as to be rotatable relative to said second unbalanced shaft (22), the idler device (31) has a follower (32) which is inserted into the second unbalanced shaft (21); - both rotation stops (33a, 33b) are provided on the second gear wheel (26), and The unbalanced exciter according to any one of claims 1 to 10, characterized in that the driver (32) abuts against one of the rotation stops (33a, 33b) depending on the flow direction of the drive torque between the two gears (25, 26).

12. the coupling device (27) comprises two gears (25, 26) which mesh with each other, each gear (25, 26) being arranged on one of the unbalanced shafts (21, 22); - both gears (25, 26) are arranged in a rotatable bearing relative to the unbalanced shaft (21, 22) which supports them, - a follower (32) is inserted into each of the two unbalanced shafts (21, 22), - both gears (25, 26) are provided with two rotation stops (33a, 33b, 34a, 34b), 12. The unbalanced exciter according to claim 1, wherein the two driving bodies (32) abut against one of the rotational stops (33 a, 33 b, 34 a, 34 b) respectively assigned to the driving bodies (32) depending on the flow direction of the drive torque between the two gears (25, 26).

13. 13. The unbalanced exciter according to claim 1, wherein both unbalanced shafts (21, 22) and both drives (23, 24) are of identical design.

14. 1. A soil compaction device comprising: - the upper mass (1), - a lower mass (2) movable relative to said upper mass (1) and provided with a soil contact plate (9) for compacting the soil; a vibration isolation device (3) acting between said upper mass (1) and said lower mass (2); at least one unbalance exciter (10) belonging to said lower mass (2) for applying an unbalance force to said soil contact plate (9); Equipped with - A soil compaction device, wherein the unbalanced exciter (10) is an unbalanced exciter according to any one of claims 1 to 13.

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