Soil compaction device and phase-adjustable unbalanced exciter with two driven shafts

Abstract

An unbalance exciter is described, comprising at least two unbalance shafts (21, 22) arranged parallel to each other; wherein each of the unbalance shafts (21, 22) has its own separately controllable drive (23, 24) for generating a drive torque; wherein a coupling device (27) is provided for coupling the two unbalance shafts (21, 22) in opposite directions; wherein the coupling device (27) has a play device (31) for enabling controlled play in the rotational positions of the two unbalance shafts (21, 22) relative to each other; and wherein the play device (31) enables play between the two unbalance shafts (21, 22) with a predetermined angle of rotation, the angle of rotation being selected from a range of 45° to 315°.

Description

[0001] The invention relates to an unbalance exciter with two parallel driven shafts and a soil compaction device that uses the unbalance exciter.

[0002] Such soil compaction devices are well known and are often referred to as vibrating plates or vibratory plates. They typically have an upper mass and a lower mass, which are usually connected by rubber buffers that serve as vibration decoupling devices.

[0003] In conventional vibrating plates, a drive in the form of an internal combustion engine is mounted on the upper mass. A drawbar with a guide bar can also be attached to the upper mass, which the operator uses to control the vibrating plate. An unbalance exciter is mounted on the lower mass, which generates vibrations that are introduced into the soil to be compacted via a ground contact plate also located on the lower mass.

[0004] Especially in small and medium-sized vibrating plates, the power of the drive motor is transferred to the unbalance exciter on the unbalance mass via a belt drive. In addition, a centrifugal clutch can be flanged to the combustion engine serving as the drive motor, so that the unbalance exciter is still decoupled from the engine at low engine speeds.

[0005] The unbalance exciter itself often has two imbalance shafts arranged parallel to each other and rotating in opposite directions, each of which carries eccentrically arranged weights (unbalance masses) in order to achieve the desired vibrations when the imbalance shafts rotate.

[0006] By changing the phase position of the imbalance shafts relative to each other, especially by changing the angular position of the imbalance shafts and thus of the respective imbalance masses relative to each other, the direction of a resulting force vector can be altered. This makes reversible the vibrating plate possible, allowing it to be moved forwards and backwards. In addition, stationary vibration can also be achieved.

[0007] Examples of unbalance exciters constructed in this way can be found in DE 24 09 417 A and DE 30 43 719 A1.

[0008] From DE 10 2020 102 949 A1, an unbalance exciter is also known in which an electric motor is provided on the lower mass to drive the unbalance exciter, wherein the electric motor is integrated into the unbalance exciter.

[0009] This unbalance exciter also enables direction switching. One of the unbalance shafts is driven by an electric motor, while the second is driven in the opposite direction via a spur gear system, whereby one of the spur gears can rotate approximately 180° relative to its unbalance shaft. A spiral or spiral groove is provided for this purpose. The relative adjustment is achieved via a hydraulically actuated, rotationally decoupled piston in the axial direction, which holds a switching pin, which in turn engages in the spiral groove. The hydraulic pressure required for the switching process is generated, for example, in a master cylinder on the guide drawbar by means of a piston with a rack, gear shaft, and switching bracket. In vibratory plates with hydraulic drive, it can also be provided by the on-board hydraulics.

[0010] The described phase adjustment of the unbalance exciter, which is particularly necessary for the direction switching or reversibility of the vibrating plate, requires numerous, comparatively expensive components. These include, for example, the drawbar head with master cylinder, gear shaft, master piston with rack, seals, hydraulic hose, adjustment cylinder, adjustment piston, rotary decoupling, piston with switching pin, and adjustment sleeves with a spiral groove. Furthermore, the hydraulic system required for the phase adjustment can be susceptible to contamination, for example, from chips.

[0011] The invention is based on the object of providing an unbalance exciter with a simplified structure which nevertheless provides the same functions as a more complex unbalance exciter.

[0012] The object is achieved according to the invention by an unbalance exciter having the features of claim 1. The unbalance exciter can advantageously be used in a soil compaction device specified in a subordinate claim. Advantageous embodiments are defined in the dependent claims.

[0013] An unbalance exciter is provided with at least two unbalance shafts arranged parallel to one another, each of the unbalance shafts having its own, separately controllable drive for generating a drive torque; a coupling device being provided for the counter-rotatable coupling of the two unbalance shafts; and the coupling device having a play device for enabling a targeted play of the rotational positions of the two unbalance shafts relative to one another.

[0014] The play device can, for example, enable a play between the two unbalanced shafts with a specified angle of rotation, whereby the angle of rotation can be selected from a range between 45° and 315°. This will be explained in more detail later, including with further examples.

[0015] The unbalance shafts consist of a shaft section on which one or more unbalance masses are arranged. For example, an unbalance shaft can have a fixed unbalance mass mounted on it, which can consist of several partial unbalance masses. This also makes it possible to distribute the (total) unbalance mass in the form of several partial unbalance masses over the length of the unbalance shaft. For example, the partial unbalance masses can be attached to each of the two end faces of the unbalance shaft. The unbalance shafts are rotatably mounted in a common exciter housing.

[0016] An example of such an unbalanced shaft is shown, for example, in DE 10 2020 102 949 A1. It is also shown there that the unbalanced shaft can be driven by an electric motor integrated directly into the unbalanced shaft. However, while in DE 10 2020 102 949 A1 only one of two unbalanced shafts is driven by an electric motor, while the other, second unbalanced shaft is coupled and dragged by a coupling device, according to the invention both unbalanced shafts are equipped with their own drive. The drive can also be integrated into the respective unbalanced shaft in the form of an electric motor. It is also possible to provide the two drives separately from the unbalanced shafts, in which case suitable torque transmission devices (e.g. belt drive or hydraulic) must be provided.

[0017] Each unbalance shaft therefore has its own, separately controllable drive.

[0018] The coupling device allows for a mechanically counter-rotating coupling of the two unbalance shafts, e.g., a positive-locking, counter-rotating coupling. "Coupling" in this context means that the rotation of the unbalance shafts is coupled to each other while maintaining the respective set phase position.

[0019] However, the strict coupling, e.g., a positive-locking coupling, is suspended or eliminated within a clearly defined range by the play device. Thus, the play device allows for targeted (rotational) play with respect to the rotational positions of the unbalanced shafts and thus to the phase position of the unbalanced shafts relative to each other. The unbalanced shafts are freely rotatable relative to each other within the play, i.e., within the specified rotation angle range.

[0020] The targeted, predefined play of the rotational positions allows a change in the phase position of the two unbalance shafts relative to each other.

[0021] The targeted play of the rotational positions means, in particular, that two extreme rotational positions of the unbalanced shafts relative to each other are possible, which can be defined, for example, by two stops. Depending on the direction of rotation or the direction of flow of the drive torque between the two unbalanced shafts, the unbalanced shafts assume one or the other extreme position relative to each other and thus one or the other phase position relative to each other. Thus, a predetermined phase position can be set depending on the direction of flow of the drive torque by utilizing the play.

[0022] The play device, which is part of the coupling device, allows two limit or relative positions of the phase positions of the two unbalanced shafts coupled by the coupling device to be defined. Depending on which limit position is assumed at the end of the play, the two unbalanced shafts are in a predefined phase position with respect to each other. The phase position, in turn, determines the direction of a force vector resulting from the rotating unbalanced masses on the unbalanced shafts (resulting force vector). The rotational positions enabled by the play device can be selected so that the resulting force vector is suitable for either forward or reverse travel.

[0023] The permissible extreme rotational positions are limited by a defined rotational angle range between 45° and 315°. The rotational angle range specifies the entire angular range, which may result from multiple, particularly partial, rotational angles (related to two unbalanced shafts). The play enabled by the play device can thus be enabled in a (total) rotational angle range between 0° and 720°, in particular between 90° and 720°, in particular between 90° and 270°, and between 450° and 720°, in particular between 45° and 315°, in particular between 90° and 270°, in particular between 120° and 240°, in particular between 150° and 210°, in particular between 175° and 185°. A rotation angle range that has proven itself in practice and is therefore preferred is ± 90°, i.e. in total (total rotation angle range) approx. 180°.

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

[0025] The play device can provide two rotation stops to define the limit positions of the rotation angle of the unbalance shafts relative to each other, as permitted by the play. The two end or rotation stops thus define two extreme positions to which the two unbalance shafts can be rotated relative to each other, corresponding to two defined different phase positions.

[0026] The two rotation stops can also be implemented by several partial rotation stops connected in series, whereby the partial rotation stops enable respective partial rotation angles which in total correspond to the entire specified rotation angle.

[0027] The two drives can be controlled in such a way that they and thus the unbalance shafts driven by them can rotate in opposite directions.

[0028] The two drives can be controlled alternately so that one of the drives generates a stronger drive torque than the other. Depending on which drive currently generates a stronger drive torque, one of the two limit positions of the two unbalanced shafts, defined by the respective rotational stop, is adjusted relative to each other. The drive torque flows from the stronger drive and the unbalanced shaft driven by it via the coupling device to the less powerful unbalanced shaft or the weaker drive.

[0029] This allows both drives to be operated simultaneously, with one of the two drives generating a stronger drive torque than the other in order to achieve a defined relative position of the two unbalanced shafts to one another and thus a defined phase position. It is also possible for only one of the drives to be driven, while the other drive is not operating or is being braked and therefore does not generate any drive torque. This non-driven or braked drive is then dragged along by the driven drive, together with its associated unbalanced shaft. The drive can also be braked specifically, for example, by operating this drive as a generator.

[0030] When switching between the drive with the higher drive torque and the associated change in the direction of drive torque flow, the rotation of the two unbalance shafts relative to each other, enabled by the play device, can be automatically triggered, thus adjusting the other phase position. The phase position is thus adjusted depending on the direction of rotation of the drives or the direction of drive torque flow of the two drives. This also applies if one of the two drives is not driving or is decelerating, meaning it is not generating any drive torque.

[0031] It is therefore possible for one of the drives to be activated while the other is not activated or is activated at lower power. The activated drive, especially the drive activated at full power, should then drag or pull the deactivated or weaker drive along.

[0032] Each of the unbalanced shafts can be driven by a separately controllable electric motor. The electric motor can have a rotor, which can be a component of the associated unbalanced shaft. In particular, the rotor can then be formed directly on the unbalanced shaft, while an associated stator can be accommodated in the exciter housing.

[0033] A "forward travel" operating state can be provided in which one of the imbalance shafts is a first imbalance shaft and the other imbalance shaft is a second imbalance shaft, in which the first imbalance shaft is driven by its assigned drive and the second imbalance shaft is not driven or is driven less strongly by the assigned drive than the first imbalance shaft, and in which, when the first imbalance shaft is driven, the play in the play device is overcome and the second imbalance shaft is dragged along by the coupling device. Overcoming the play is understood to mean that one of the rotation stops is effective at a time, and thus the two imbalance shafts assume a defined phase position with respect to one another.

[0034] As an alternative to the “forward travel” operating state, a “reverse travel” operating state can be provided, in which the second unbalanced shaft is driven by the drive assigned to it and the first unbalanced shaft is not driven or is driven by the drive assigned to it to a lesser extent than the second unbalanced shaft, and in which, when the second unbalanced shaft is driven, the play in the play device is overcome and the first unbalanced shaft is dragged along by the coupling device.

[0035] Furthermore, a "stationary vibration" operating mode can be provided, which involves repeated switching between the "forward travel" and "reverse travel" operating modes. The periods during which the "forward travel" and "reverse travel" operating modes are activated are identical, but each shorter than 5 seconds. The "stationary vibration" operating mode enables spot compaction using a vibrating plate equipped with the unbalance exciter, i.e., compaction on the spot without the vibrating plate moving forward or backward.

[0036] The "stationary vibration" operating mode is achieved by quickly switching between forward and reverse travel, namely before the vibrating plate can travel in the corresponding direction. Since the vibrating plate has a large inertial mass, it generally requires a certain amount of time to start moving, even if the resulting force vector is already aligned in one direction. Before the vibrating plate can thus begin moving, the direction of travel in the unbalance exciter is switched by switching the operating mode from forward to reverse and vice versa, so that the vibrating plate ultimately remains stationary. The time required to switch between forward and reverse travel should preferably be selected so that the respective rotation stop reaches its defined limit position.

[0037] The specified maximum period of 5 seconds may be too long depending on the design. Accordingly, the period can also be less than 4 seconds, less than 3 seconds, less than 2 seconds, or less than 1 second. For example, the two drives of the unbalance shafts can be driven alternately every 2 seconds to alternate between forward and reverse travel and thus achieve stationary vibration.

[0038] In addition or alternatively, a “slow travel” operating mode can be provided in which repeated switching between the “forward travel” and “reverse travel” operating modes takes place, whereby the time periods in which the “forward travel” and “reverse travel” operating modes are activated vary depending on the desired direction of travel, but are always shorter than 8 seconds, e.g. shorter than 5 seconds or shorter than 3 seconds. In this operating mode, the “stationary vibration” operating mode described above is thus varied. Here, too, there is regular, relatively rapid switching between forward travel and reverse travel. However, while the respective time periods for forward travel and reverse travel are identical for stationary vibration, the time periods for the “slow travel” operating mode are different.For example, for slow forward travel, the time period for forward travel is specified to be slightly longer than for reverse travel. This ensures that the resulting force vector for forward travel acts slightly longer than that for reverse travel, resulting in slow forward travel due to the high inertia of the vibrating plate.

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

[0040] The above definitions of "first unbalance shaft" and "second unbalance shaft" are arbitrary. For example, the unbalance shaft that is driven in the "forward" operating mode could always be defined as the "first unbalance shaft." The second unbalance shaft would then be the other unbalance shaft, or the unbalance shaft that is driven in the "reverse" operating mode.

[0041] Each of the unbalanced shafts can carry a gearwheel, with the gearwheels meshing with each other, and one or both of the gearwheels being rotatable relative to the respective unbalanced shaft over an angular range defined by rotation stops. The gearwheels can be part of the coupling device and transmit the drive torque from one unbalanced shaft to the other. The relative rotatability of the two gearwheels (or just one gearwheel) relative to the associated unbalanced shaft makes it possible to adjust the different phase positions. Accordingly, rotation stops are provided to define the relative rotation of the gearwheels (or the gearwheel).

[0042] The backlash device can have two rotation stops on one of the unbalanced shafts, which are rotated relative to each other by an angle corresponding to the specified rotation angle range. The two rotation stops then form the end stops for the two predefined phase positions of the unbalanced shafts. For example, the rotation stops can be rotated relative to each other by an angle of approximately 180°.

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

[0044] The coupling device can have two intermeshing gears, each of which is arranged on one of the unbalanced shafts, wherein one of the gears is a first gear that is fixedly arranged on the first unbalanced shaft, wherein the other of the gears is a second gear that is mounted on the second unbalanced shaft so as to be rotatable relative to the latter, wherein the play device has a driver that is inserted into the second unbalanced shaft, wherein the two rotation stops are provided on the second gear, and wherein the driver strikes one of the rotation stops depending on the direction of flow of the drive torque between the two gears.

[0045] In this variant, one of the gears is fixedly mounted on the (first) unbalanced shaft, while the gear on the second unbalanced shaft can be rotated within the rotation angle range.

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

[0047] In one variant, the coupling device can have two intermeshing gears, each arranged on one of the unbalanced shafts. Both gears are rotatably mounted relative to the unbalanced shaft supporting them. A driver is inserted into each of the two unbalanced shafts. Two rotation stops are provided on each of the gears. Depending on the direction of flow of the drive torque between the two gears, the two drivers strike one of the rotation stops assigned to them. Here, too, the drivers can be designed, for example, as pins or bolts.

[0048] In this alternative variant, both gears can be rotated relative to the unbalanced shaft assigned to them, in particular by a partial angle of rotation, so that the sum of the partial angles of rotation (e.g. 90° each) results in the total specified angle of rotation (e.g. 180°).

[0049] With this latter variant, it is possible for both unbalance shafts and both drives to be constructed identically. This can also apply to the coupling device and the backlash device, i.e., the gears, the rotation stops, and the drivers (e.g., pins). This allows for the use of a very large number of identical parts. The complete unbalance shafts can be completely identical and installed in the exciter housing.

[0050] The described unbalance exciter can be used particularly advantageously in a soil compaction device, such as a vibrating or vibrating plate.

[0051] Accordingly, a soil compaction device is also specified, comprising an upper mass, a lower mass movable relative to the upper mass, a ground contact plate for concrete compaction, a vibration decoupling device acting between the upper mass and the lower mass, and at least one unbalance exciter belonging to the lower mass for applying an unbalance force to the ground contact plate, wherein the unbalance exciter is an unbalance exciter of the type described above.

[0052] These and other advantages and features are explained in more detail below using examples and the accompanying figures. They show: Fig. 1 a soil compaction device according to the invention in side view; Fig. 2 an unbalance exciter in a sectional top view and a perspective partial view; Fig. 3 a variant of the unbalance exciter from Fig. 2; Fig. 4 an example of the position of the coupling device and the play device in the “forward travel” operating mode; Fig. 5 an example of the position of the coupling device and the play device in the “reverse” operating mode at the time of switching; Fig. 6 the operating status of Fig. 5, but at a time after the unbalance shafts have completed a rotation of 90°; Fig. 7 a variant of Fig. 4, with an example of the position of the coupling device and play device in the “forward travel” operating mode; Fig. 8 in the variant of Fig. 7 an example of the position of the coupling device and the play device in the “reverse” operating mode at the time of switching; and Fig. 9 the operating status of Fig. 8, but at a time after the unbalance shafts have completed a rotation of 270°.

[0053] Fig. 1 shows an example of a vibrating plate used as a soil compaction device.

[0054] The vibrating plate comprises an upper mass 1 and a lower mass 2 that is movable relative to the upper mass 1. The lower mass 2 is coupled to the upper mass 1 via rubber buffers 3 that serve as a vibration decoupling device. In this way, the strong vibrations generated by the lower mass 2 are transmitted to the upper mass 1 in a dampened manner.

[0055] The upper mass 1 has a supporting frame 4 on which a battery 5 and a converter 6 are mounted, which are also assigned to the upper mass 1. The battery 5 and the converter 6 are enclosed by a protective frame 7.

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

[0057] The lower mass 2 has a soil contact plate 9, which can be used to compact the soil underneath. A vibration exciter or imbalance exciter 10, which also belongs to the lower mass 2, is arranged on the upper side of the soil contact plate 9.

[0058] In the prior art, such unbalance exciters are usually driven by motors, especially internal combustion engines, which are arranged on the upper mass. However, according to the invention, two Fig. 1 electric motors not shown are integrated directly into the unbalance exciter 10, as will be explained below.

[0059] To guide the vibrating plate, a guide bar 11 is also attached to the upper mass 1 or the support frame 4. A speed lever (not shown) can be provided on the guide bar 11 to influence the motor speeds of the electric motors serving as drive motors. Depending on the design, an on / off switch may also be sufficient to switch on the electric motors (explained later).

[0060] At the upper end of the guide bar 11, a guide bar or control handle 12 is arranged, via which the relative rotational position of the unbalance shafts in the unbalance exciter 10, in particular their phase relationship to each other, can be adjusted, as will be explained later. In this way, forward and reverse travel of the vibrating plate can be achieved in a conventional manner.

[0061] A wheel arrangement with two axially arranged wheels 13 is provided on the lower mass 2 or the ground contact plate 9. In the Fig. In the normal state shown in Figure 1, the wheels 13 hover above the ground. However, by tilting the vibrating plate, it is possible to bring the wheels 13 into contact with the ground, so that the ground contact plate 9 is completely lifted off the ground. In this tilted or transport state, the vibrating plate can be easily moved and transported using the wheels 13.

[0062] The unbalance exciter 10 has an exciter housing 20 which, as Fig. 1 shows, is applied directly to the ground contact plate 9 in order to be able to optimally introduce the vibrations generated by the unbalance exciter 10 into the ground contact plate 9 and thus into the soil to be compacted.

[0063] Fig. 2 shows the unbalance exciter 10 in a sectional top view.

[0064] Inside the exciter housing 20, two unbalanced shafts are rotatably mounted, namely a first unbalanced shaft 21 and a second unbalanced shaft 22. 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 coupled to rotate in opposite directions. For this purpose, a gear pair is provided, with 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 Fig. 2 also shows this in perspective in the right-hand part of the image. In this way, a rotation of one unbalanced shaft is directly translated into a counter-rotation of the other unbalanced shaft, depending on which of the two unbalanced shafts 21, 22 is driven.

[0066] The first unbalanced shaft 21 carries a first unbalanced mass 28, which is divided into two partial mass elements 28a, 28b. The two partial mass elements 28a, 28b are axially spaced from each other and arranged at the front ends of the first unbalanced shaft 21.

[0067] The second unbalance shaft 22 in turn carries a second unbalance mass 29, which is formed by partial mass elements 29a, 29b.

[0068] Both unbalanced shafts 21, 22 are mounted on roller bearings. Unbalanced masses 28, 29 are located on all four shaft ends. Gears 25, 26 are arranged between the roller bearings and the respective unbalanced masses 28, 29. The mechanical coupling of the two unbalanced shafts 21, 22 is subject to considerable backlash, so that if one shaft is held in place, the other can be rotated by approximately ± 90°, as will be explained later.

[0069] The two electric motors 23, 24 are arranged in the middle area of ​​each of the two unbalanced shafts 21, 22. Both electric motors 23, 24 can be individually controlled and can serve alternately as drive motors. For example, it is possible to activate only one of the electric motors 23, 24 while the other electric motor 23, 24 is driven along. It is also possible to operate both electric motors 23, 24, whereby - as will be explained later - depending on the desired phase position, one of the electric motors 23, 24 should provide a lower drive torque than the other. The direction of rotation of the two electric motors 23, 24 is opposite, as indicated by arrows A (for the first unbalanced shaft 21 or the first electric motor 23) and B (for the second unbalanced shaft 22 or the second electric motor 24).

[0070] The electric motors 23, 24 can be integrated into the unbalanced shafts 21, 22 that support them. In particular, it is possible for the electric motors 23, 24 to each have a rotor mounted directly 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 functions as the motor shaft of the electric motor 23, 24.

[0071] An example of a rotor is shown in the figure which will be explained later. Fig. 3 is marked with the reference number 30.

[0072] The rotors are each enclosed by a stator, which also belongs to the respective electric motor 23, 24 and is suitably mounted in the exciter housing 20. However, the electric motors 23, 24 can also be installed as complete units in the exciter housing 20. The exciter housing 20 thus supports both stators of the electric motors 23, 24 as well as the roller bearings of the imbalance shaft 21, 22. It is therefore advantageous if the electric motors 23, 24 are fully integrated into the imbalance exciter 10. An external drive of the imbalance exciter 10, as is widely known from the prior art, is therefore not necessary. The imbalance exciter 10 forms an integral unit with the two integrated electric motors 23, 24 and requires no further external drive.

[0073] The two electric motors 23, 24 are shown merely as examples. Solutions are also possible in which the electric motors are located outside the exciter housing 20. Hydraulic motors can also be used. The motors can be mounted externally on the exciter and outside the unbalance masses.

[0074] The first gear 25 is fixedly mounted on the first unbalance shaft 21 in a rotationally fixed manner, e.g. by means of a suitable shaft-hub connection, such as a key or a clamp fit.

[0075] In the right part of the picture Fig. In the perspective detail enlargement shown in Figure 2, a gaming device 31 is shown.

[0076] The second gear 26, which meshes with the first gear 25 and thus rotates in the opposite direction, is mounted on the second unbalanced shaft 22. The play device 31 is provided, which allows a defined play in the form of relative rotatability of the second gear 26 relative to the second unbalanced shaft 22 supporting the gear 26. The play device 31 has a bolt or pin 32, which is received vertically in the second unbalanced shaft and serves as a driver and can selectively strike against stops 33a and 33b. The second gear 26 is thus rotatably mounted on the second unbalanced shaft 22, with the rotatability being limited by the interaction of the pin 32 and the two stops 33a, 33b.

[0077] The pin 32 also acts together with the unbalanced mass 29 arranged behind it as an axial securing means for the rotatable second gear 26 arranged therebetween.

[0078] In the example shown, the two stops 33a, 33b are designed such that the second gear 26 can be rotated by 180° relative to the second unbalanced shaft 22, depending on the direction of action of the driving torque.

[0079] In relation to the Fig. 2 with the directions of rotation A and B, and assuming that only the first electric motor 23 is driving while the second electric motor 24 is switched off, the first gear 25 drives the second gear 26 in the direction of arrow B in the direction of arrow A. Since the second electric motor 24 is switched off, it generates a frictional or drag torque and brakes. Accordingly, the second gear 26 drives the second unbalanced shaft 22 via the stop 33a and the pin 32, also in the direction of rotation B.

[0080] In a reverse situation, which is Fig. 2 is not shown, the second electric motor 24 drives alone, while the first electric motor 23 is switched off. In this case, the second unbalanced shaft 22 rotates in the direction of arrow B, so that the pin 32, utilizing the play, rotates downward by 180° until it strikes the stop 33b. Then, the pin 32 also drives the second gear 26 in the direction of rotation B, whereupon the first gear 25, together with the first unbalanced shaft 21, rotates in the direction of arrow A.

[0081] Due to the free, i.e. uncoupled pivoting of the second unbalanced shaft 22 by 180° relative to the first unbalanced shaft 21, which is still stationary during the pivoting process, the unbalanced masses 29 carried by the second unbalanced shaft 22 are placed in a different relative position and thus phase position to the unbalanced masses 28 of the first unbalanced shaft 21. A changed direction of action of the resulting force is the consequence, as will be shown later with reference to the Fig. 4 to 6 is explained.

[0082] The play device 31 with the pin 32 and the stops 33a, 33b are merely an example. Other solutions are also conceivable for the realization of the play device 31, e.g. steps and stop surfaces arranged directly on the respective unbalance shaft.

[0083] Fig. 3 shows a variant of the unbalance exciter from Fig. 2. Reference is made to the reference numerals of Fig. 2 is referred to.

[0084] In contrast to the embodiment of Fig. 2 are in the variant of Fig. 3 both gear wheels 25, 26 can be pivoted over a defined angular range - namely 90° each - relative to the unbalanced shaft 21, 22 carrying them.

[0085] While the variant of Fig. 2 the play device 31 was arranged only on one of the unbalanced shafts (in the example shown on the second unbalanced shaft 22) and allowed a play over the entire defined angle of rotation, in the variant of Fig. 3 the play device 31 on both unbalance shafts 21, 22, as shown in the enlarged perspective view in the right part of Fig. 3. In particular, a first play device 31a is provided on the first unbalanced shaft 21 and a second play device 31b is provided on the second unbalanced shaft 22, with a pin 32a and 32b. In addition, analogous to the variant of Fig. 2 stops 33a and 33b are provided on the second unbalanced shaft 22 and stops 34a, 34b on the first unbalanced shaft 21.

[0086] While the stop surfaces 33a, 33b in the variant of Fig. 2 are offset by an angle which allows a rotation angle of the second gear 26 relative to the unbalanced shaft 22 of 180°, the stop surfaces 33a, 33b, 34a, 34b in the variant of Fig. 3 is designed in such a way that a relative rotation of the two gears 25, 26 relative to the unbalanced shafts 21, 22 carrying them with a rotation angle of 90° is possible. In total, however, this results in a total rotation angle of 180°, analogous to Fig. 2.

[0087] With regard to the force vector resulting from the rotation of the unbalance shafts 21, 22, the variants differ from Fig. 2 and Fig. 3 does not. In the variant of Fig. 3, however, it is possible to design both unbalance shafts 21, 22 including the other components used as identical parts, which further reduces the number of components to be used.

[0088] When the first unbalanced shaft 21 is driven in rotation in the direction of arrow A by the first electric motor 23 provided there, while the second electric motor 24 on the second unbalanced shaft 22 is not operated or is operated only weakly, the pin 32a presses against the stop surface of the stop 34a, causing the gear 25 to rotate in the direction of arrow A and the second gear 26 to rotate in the direction of arrow B. The second gear 26, via its stop 33a, carries the pin 32b along and thus drags the second unbalanced shaft 22 with the second electric motor 24.

[0089] Fig. Figure 4 shows a schematic view of the two gear wheels 25, 26 and the unbalanced masses 28, 29 located behind them, which are shown only in dashed lines.

[0090] The phase position for forward travel in the forward direction V is shown, as indicated by an arrow. The first unbalanced shaft 21 is driven in the direction of rotation A. The effect of the rotating unbalanced mass 28 generates a force vector F1.

[0091] The situation is shown, which has already been described above with reference to Fig. 2. Accordingly, the second gear 26 with the second unbalanced mass 29 is rotated in the direction of arrow B. The rotational effect generates the centrifugal force F2. The two centrifugal forces F1, F2 overlap and form a centrifugal force directed in the same direction, Fig. 4 Resultant force not shown. The resulting force has oscillating components in the vertical direction, which are used for soil compaction, as well as a component in the horizontal direction, which in this case is directed in the direction of travel V. In this way, the vibrating plate using the imbalance exciter can be moved in the forward direction V.

[0092] Fig. 5 shows the moment of switching from forward to reverse, starting from the situation in Fig. 4. To reach the switching 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 arrow B. As a result, the pin 32 rotates by 180° - according to the arrangement of the stops 33a, 33b - and thus reaches the Fig. 5. In this situation, the pin 32 touches the stop 33b and begins to rotate the second gear 26 in the direction of arrow B. The second unbalanced mass 29 coupled thereto generates an unbalance force F2 directed in the reverse direction R.

[0093] In this situation, the first unbalance shaft 21 is still unchanged and has changed compared to the situation of Fig. 4 is not moving, especially not rotating. This only occurs upon further rotation of the now driving second unbalanced shaft 22.

[0094] Fig. Figure 6 shows a situation in which, starting from the situation of Fig. 5 the two unbalanced shafts 21, 22 and thus also the gears 25, 26 and the unbalanced masses 28, 29 have rotated 90° in their respective directions of rotation A, B. It can be seen that the force vectors F1, F2 are directed in the reverse direction R, so that reverse travel can be achieved. To continue the reverse travel, the second electric motor 24 and thus the second unbalanced shaft 22 are rotated further in the direction of rotation B, while the first unbalanced shaft 21 is dragged along with the first electric motor 23 in the direction of rotation A.

[0095] The Fig. 7 to 9 show a variant of the unbalance exciter of the Fig. 4 to 6. While in the variant of the Fig. 4 to 6 in the case of a stationary vibration the full centrifugal force of the exciter or of a vibrating plate supporting it is not effective, the unbalance exciter can Fig. 7 to 9, a strong oscillating vertical force can also be generated in the operating state of the stand vibration.

[0096] The structure of the two variants is essentially identical.

[0097] Opposite the Fig. 4 is also in the operating state “forward travel” Fig. 7, however, the second unbalanced shaft 22 is driven and the second unbalanced mass 29 is structurally rotated by 180° relative to the unbalanced shaft 22, as a comparison of the two figures shows. The first unbalanced shaft 21 is dragged along in this state. The two centrifugal forces F1 and F2 are to the variant of Fig. 4 identical.

[0098] The definition of "first unbalance shaft" and "second unbalance shaft" is arbitrary and was chosen in the example shown to facilitate comparison between the two variants. Thus, the unbalance shaft that is driven in the "forward" operating mode could easily be defined as the "first unbalance shaft." The second unbalance shaft would then be the other unbalance shaft, or the unbalance shaft that is driven in the "reverse" operating mode.

[0099] Fig. 8 shows the moment of switching from forward to reverse, starting from the situation of Fig. 7 and thus similar to Fig. 5. Now the second electric motor 24 is switched off so that the second unbalance shaft 22 is no longer driven.

[0100] Instead, the first electric motor 23 is activated and the first unbalanced shaft 21 is driven in the direction of arrow A. As a result, the pin 32 on the second unbalanced shaft 22 rotates relative to the stops 33a, 33b.

[0101] Fig. Figure 9 shows a situation in which, starting from the situation of Fig. 8 the two unbalanced shafts 21, 22 and thus also the gears 25, 26 and the unbalanced masses 28, 29 have rotated 270° in their respective directions of rotation A, B. It can be seen that the force vectors F1, F2 are directed in the reverse direction R, so that reverse travel can be achieved. To continue the reverse travel, the first electric motor 23 and thus the first unbalanced shaft 21 are rotated further in the direction of rotation A, while the second unbalanced shaft 22 is dragged along with the second electric motor 24 in the direction of rotation B. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 24 09 417 A

[0007] DE 30 43 719 A1

[0007] DE 10 2020 102 949 A1 [0008, 0016]

Claims

[1] Unbalance exciter, with at least two unbalance shafts (21, 22) arranged parallel to one another; wherein - 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 the counter-rotatable coupling of the two unbalance shafts (21, 22); and wherein - the coupling device (27) has a play device (31) to enable a targeted play of the rotational positions of the two unbalance shafts (21, 22) relative to one another. [2] Unbalance exciter according to claim 1, wherein the play device (31) provides at least two rotation stops (33a, 33b) for defining the limit positions of the angle of rotation made possible by the play. [3] Unbalance exciter according to one of the preceding claims, wherein - the two drives (23, 24) can be controlled alternately in such a way that one of the drives generates a stronger drive torque than the other; and wherein - depending on which drive currently generates a stronger drive torque, one of the two limit positions of the two unbalance shafts (21, 22) defined by the respective rotation stop is set relative to each other. [4] Unbalance exciter according to one of the preceding claims, wherein an operating state “forward travel” is provided in which - 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 (23) assigned to it and the second unbalanced shaft (22) is not driven or is driven by the drive (24) assigned to it less strongly than the first unbalanced shaft (21); and in which - when driving the first unbalanced shaft (21), the play in the play device (31) is overcome and the second unbalanced shaft (22) is dragged along by the coupling device (27). [5] Unbalance exciter according to one of the preceding claims, wherein an operating state “reverse travel” is provided in which - the second unbalanced shaft (22) is driven by the drive (24) assigned to it and the first unbalanced shaft (21) is not driven or is driven by the drive (23) assigned to it less strongly than the second unbalanced shaft (22); and in which - when driving the second unbalanced shaft (22), the play in the play device (31) is overcome and the first unbalanced shaft (21) is dragged along by the coupling device (27). [6] Unbalance exciter according to claims 4 and 5, wherein - a "stationary vibration" operating mode is provided in which repeated switching between the "forward travel" and "reverse travel" operating modes takes place; - the periods during which the operating mode "forward travel" and the operating mode "reverse travel" are activated are identical, but each shorter than 5 seconds. [7] Unbalance exciter according to claims 4 and 5, wherein - a "slow travel" operating mode is provided in which repeated switching between the "forward travel" and "reverse travel" operating modes takes place; and - the periods during which the operating mode "forward travel" and the operating mode "reverse travel" are activated vary depending on the desired direction of travel, but are each shorter than 8 seconds. [8] Unbalance exciter according to one of the preceding claims, wherein - both unbalanced shafts (21, 22) each carry a gear (25, 26); - the gears (25, 26) are arranged to mesh with each other; and wherein - one or both of the gear wheels (25, 26) can be rotated relative to the unbalanced shaft (21, 22) carrying them over an angular range defined by rotation stops (33a, 33b). [9] Unbalance exciter according to one of the preceding claims, wherein the play device (31) on one of the unbalance shafts (22) has two rotation stops (33a, 33b) which are rotated relative to one another by an angle corresponding to the predetermined rotation angle range. [10] Unbalance exciter according to one of the preceding claims, wherein - the play device (31) has two rotation stops (33a, 33b, 34a, 34b) on each of the two unbalanced shafts (21, 22), which are rotated relative to each other by a partial angle of rotation; and wherein - the sum of the partial rotation angles corresponds to the specified rotation angle range. [11] Unbalance exciter according to one of the preceding claims, wherein - the coupling device (27) has two meshing gears (25, 26), each of which is arranged on one of the unbalanced shafts (21, 22); - one of the gears is a first gear (25) which is fixedly arranged on the first unbalanced shaft (21); - the other of the gears is a second gear (26) which is mounted on the second unbalanced shaft (22) so as to be rotatable relative to the latter; - the play device (31) has a driver (32) which is inserted into the second unbalance shaft (21); - the two rotation stops (33a, 33b) are provided on the second gear (26); and wherein - the driver (32) strikes one of the rotation stops (33a, 33b) depending on the flow direction of the drive torque between the two gear wheels (25, 26). [12] Unbalance exciter according to one of the preceding claims, wherein - the coupling device (27) has two meshing gears (25, 26), each of which is arranged on one of the unbalanced shafts (21, 22); - both gear wheels (25, 26) are arranged so as to be rotatable relative to the unbalanced shaft (21, 22) carrying them; - a driver (32) is inserted into each of the two unbalance shafts (21, 22); - two rotation stops (33a, 33b, 34a, 34b) are provided on each of the two gear wheels (25, 26); - the two drivers (32) strike one of the rotation stops (33a, 33b, 34a, 34b) assigned to them, depending on the direction of flow of the drive torque between the two gear wheels (25, 26). [13] Unbalance exciter according to one of the preceding claims, wherein both unbalance shafts (21, 22) and both drives (23, 24) are constructed identically. [14] Soil compaction device, with - an upper mass (1); - a lower mass (2) movable relative to the upper mass (1), with a ground contact plate (9) for soil compaction; - a vibration decoupling device (3) acting between the upper mass (1) and the lower mass (2); and with - at least one unbalance exciter (10) belonging to the lower mass (2) for applying an unbalance force to the ground contact plate (9); wherein - the unbalance exciter (10) is an unbalance exciter according to one of the preceding claims.

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