FI3862487T3

FI3862487T3 - Vibration plate with electric drive

Info

Publication number: FI3862487T3
Application number: FIEP21153873.1T
Authority: FI
Inventors: Walter Unverdorben
Original assignee: Wacker Neuson Prod Gmbh & Co
Priority date: 2020-02-05
Filing date: 2021-01-27
Publication date: 2023-07-17
Also published as: EP3862487A1; DK3862487T3; DE102020102949A1; EP3862487B1

Description

1 EP3 862 487

VIBRATION PLATE WITH ELECTRIC DRIVE

Description

The invention relates to a ground compaction device, in particular a vibration plate or plate compactor.

Such ground compaction devices or vibration plates are known and typically have an upper mass and a lower mass which are usually connected to one another by rubber buffers serving as a vibration decoupling device.

With known vibration plates, a drive in the form of an internal combustion engine is provided on the upper mass. In addition, a drawbar with a guide bar can be fastened to the upper mass, with the aid of which the operator controls the vibration plate. An unbalance exciter is provided on the lower mass and serves to generate vibrations which are introduced into the ground to be compacted via a ground contact plate likewise provided on the lower mass.

Especially with small and medium-sized vibration plates, the power of the drive motor is transmitted to the unbalance exciter on the unbalance mass with the aid of a belt drive. In addition, a centrifugal clutch can be flange-mounted on the internal combustion engine serving as a drive motor so that the unbalance exciter remains decoupled from the motor at low engine speeds.

The unbalance exciter itself often has two unbalance shafts which are arranged parallel to one another so as to be able to rotate in opposite directions, and which each carry unbalanceally arranged weights (unbalance masses) in order to be able to achieve the desired vibrations during rotation of the unbalance shafts.

By changing the phase angle of the unbalance shafts relative to one another, in particular by changing the angular position of the unbalance shafts and therefore of the respective unbalance masses, the direction of a resulting force vector can be changed. In this way, reversibility of the vibration plate is possible so that the vibration plate can be moved forward and backward. In addition, stationary vibration can also be achieved.

2 EP3 862 487

Examples of unbalance exciters made in this way are found in DE 24 09 417 A and DE 30 43 719 A1.

During operation of such a vibration plate, the belt drive is highly stressed. This is in particular due to the fact that the relative position of the two pulleys on the upper massandon the lower mass changes constantly due to the strong vibrations. In particular, the spacing of the pulleys and also their parallelism can fluctuate, which increases the stress on the drive belt. In addition, since the belt stretches during operation, slippage can arise which leads to rotational speed fluctuations in the unbalance exciter. Due to the increased wear on the drive belt, the maintenance effort is also increased.

The bearing and toothed wheels of such an unbalance exciter are usually lubricated with oil. When operating the unbalance exciter, not only the unbalance shafts must be set in rotation. In addition, drive energy is also required to overcome frictional losses which are caused primarily by the unbalance masses which circulate the oil provided for lubrication in the unbalance exciter.

A ground compaction device is known from DE 10-2017-121 177 A1 with an upper mass and a lower mass which is elastically coupled to the upper mass and has a ground contact plate. Arranged on the ground contact plate is a vibration exciter which is driven by an electric motor. The unbalance masses of the vibration exciter can be an integral component of the motor shaft of the electric motor.

DE 11 2016 000 636 T5 describes a vibration compactor that can be used in a road roller, with a vibration device which is arranged in a roller drum. The vibrating device has one shaft and three unbalance masses. A motor for rotating the masses around the shaft is provided for each unbalance mass.

The object of the invention is to present an improved ground compaction device in which the disadvantages present in the prior art can be avoided.

The object is achieved according to the invention by a ground compaction device having the features of claim 1. Advantageous embodiments are presented in the dependent claims.

3 EP3 862 487

A ground compaction device is presented with an upper mass, with a lower mass movable relative to the upper mass, with a ground contact plate for ground compaction, with a vibration decoupling device acting between the upper mass and the lower mass, and with at least one unbalance exciter associated with the lower mass for applying an unbalance force to the ground contact plate. An electric motor for driving the unbalance exciter is provided on the lower mass, wherein the electric motor is integrated into the unbalance exciter.

Such a ground compaction device can in particular be a vibration plate or a plate compactor with which ground can be compressed in an effective manner or stones can be vibrated into ground.

The basic structure of such a ground compaction device with an upper mass and a lower mass movable relative thereto is known. According to the invention, however, the electric motor serving as a drive motor is integrated directly into the unbalance exciter located on the lower mass so that no force transmission paths are required from the electric motor to the unbalance exciter. In this way, it is, for example, not necessary to provide an additional belt drive which has the disadvantages explained above.

The unbalance force generated by the unbalance exciter can be generated in particular as an oscillating, directed force vector.

For this purpose, the unbalance exciter has two unbalance shafts which are arranged parallel to one another, are rotatably coupled to one another in opposite directions, and each bear an unbalance mass. The two unbalance shafts can be coupled, for example, by means of a gear pair borne by the unbalance shafts.

Such a design is known per se for unbalance exciters and has proven itself in a variety of ways in practice. In contrast to unbalance exciters known from the prior art, however, the drive motor (electric motor) is integrated in the unbalance exciter.

As a result of the unbalance shafts rotating in opposite directions, a resulting force vector is generated, the orientation of which is determined depending on the relative rotational position of the unbalance masses or unbalances relative to one another. The oscillating force vector changes the amount and sign or direction with

4 EP3 862 487 the rotation of the unbalance shafts and therefore generates a force which, depending on the oscillation phase, is directed upward and lifts the ground contact plate slightly off the ground or — after rotating by 180°, is directed downward and can be introduced into the ground to be compacted by the ground contact plate.

One of the unbalance shafts can be designed as a drive unbalance shaft and have a region which forms part of the electric motor in such a way that the drive unbalance shaft is also the motor shaft of the electric motor. In this way, the electric motor can be integrated particularly efficiently into the unbalance exciter.

In this respect, the drive unbalance shaft can also be referred to as the first unbalance shaft of the two unbalance shafts of the unbalance exciter. It can be very advantageously formed in one piece so that it has regions which carry the unbalance mass or the unbalance, and has regions which are part of the electric motor.

The additional unbalance shaft of the unbalance exciter is also referred to below as the second unbalance shaft. Furthermore, it is also possible for the unbalance exciter to have additional unbalance shafts (third unbalance shaft, fourth unbalance shaft, etc.).

Effectively, a phase adjustment device can be provided between the two unbalance shafts for adjusting the phase position of the two unbalance shafts relative to one another. By adjusting the phase position of the two unbalance shafts and therefore also the unbalance masses carried by the unbalance shafts, the orientation of the resulting force vector can be set.

The phase adjustment device can in particular be integrated in the rotary coupling of the two unbalance shafts with one another and can be constructed in a manner known per se. For example, it can have an adjusting sleeve which can be rotated by the axial adjustment of a switching pin.

For the rotary coupling of the two unbalance shafts to one another and to therefore cause the counter rotation of the two unbalance shafts, two intermeshing gear wheels can be provided between the two unbalance shafts, wherein the rotational position of one of the gear wheels can be changed relative to the unbalance shaft

EP3 862 487 bearing this gear wheel by means of the adjusting sleeve assigned to this gear wheel in order to bring about the phase adjustment.

The mode of operation of such a phase adjustment device is known from the prior art, for example from the aforementioned publications DE 24 09 417 A and DE 30 43 719 5 A1, and therefore does not have to be explained in more detail at this juncture.

With the aid of the phase adjustment device, it is therefore possible to change the orientation of the resulting force vector and to bring about a reverse in direction (reversal), for example.

The electric motor in the unbalance exciter can have a rotor which is arranged on the drive unbalance shaft. Accordingly, the drive unbalance shaft in this case is also the motor shaft of the electric motor. The rotor is borne by the drive unbalance shaft.

Furthermore, the electric motor can have a stator which at least partially surrounds the rotor arranged on the drive unbalance shaft. The stator can accordingly be arranged directly in the housing of the unbalance exciter and can be borne by the unbalance exciter housing.

All types of electric motors, such as synchronous machines, asynchronous machines or also BLDC motors, are suitable as the electric motor.

The drive unbalance shaft can bear two unbalance masses which are axially mutually spaced-apart from one another, wherein the electric motor is disposed axially between the two unbalance masses. In this case, the rotor can in particular be disposed axially between the two unbalance masses.

In one embodiment, the axially mutually spaced-apart unbalance masses can be arranged at the end-face ends of the drive unbalance shaft. In this way, a very compact design of the unbalance shaft can be realized. In addition, by arranging the two unbalance masses at the two end-face ends, it can be achieved that the installation space therebetween is available completely for the electric motor with the stator and the rotor.

6 EP3 862 487

In one embodiment, it is possible for the rotor of the electric motor to rotate in a plane or an axial height which corresponds approximately to a rotational plane or axial height in which the unbalance mass of the other unbalance shaft rotates. The rotor on the one hand and this unbalance mass on the other hand then rotate at a height relative to one another.

A wheel assembly can be provided on the lower mass in order to transport the ground compaction device as required. In this way, the pair of wheels can be attached to the lower mass, in particular to the ground contact plate. During working mode, the wheels can be released from the ground and, so to speak, float above the ground. By tilting the ground compaction device, the wheels can be brought into contact with the ground in order to push the ground compaction device with the aid of the wheel assembly.

Such a wheel assembly is known, for example, from DE 102 26 920 B4.

An energy storage device for supplying electrical energy to the electric motor can be provided on the upper mass. The energy storage device can in particular be a rechargeable electrical battery. The rechargeable battery can either be permanently installed or exchangeable. Accordingly, it is possible to charge the battery either directly in the device, for example with the help of a corresponding power supply unit, or also outside in a corresponding charging station to be provided for this purpose or also via a power supply unit.

If the rechargeable battery can be replaced, it is advantageous if the rechargeable battery can be easily exchanged, for example with the help of a plug-in connection.

A converter device may be provided on the upper mass for converting an electric current provided by the energy storage device into a current suitable for the electric motor. In order to achieve vibrations and vibration frequencies advantageous for ground compaction, it is necessary for the electric motor to reach a corresponding rotational speed. In order to achieve this rotational speed, it is advantageous if the motor designed, for example, as an asynchronous machine receives a power supply with a corresponding frequency which, however, deviates from the frequency of the public grid (50 Hz). Accordingly, the converter is

7 EP3 862 487 provided to provide a higher frequency current. In addition, however, the voltage can also be adapted to a level suitable for the motor.

The converter device can have a housing on which a plug-in connection for plugging in the energy storage device is provided. Accordingly, it is easily possible to plug in the energy storage device into the plug-in connection or to pull it off the plug-in connection after use. In this case, it is also possible for a corresponding mounting or support to be provided on the housing of the converter device so that the energy storage device can be reliably mounted on the housing of the converter device.

The unbalance exciter thus specified can accordingly have a very compact design.

In particular, it has the electric motor with the drive unbalance shaft as the first unbalance shaft, and the second unbalance shaft in which the phase adjustment device can be integrated.

The unbalance exciter forms an integral unit with the electric motor and does not require any further external drive.

The drive motor known in the prior art is therefore replaced by an electric motor which is seated directly on one of the unbalance shafts. The unbalance masses on the second unbalance shaft are entrained via a gear unit with an intermediate phase adjustment device. The rechargeable battery is provided as an energy storage device on the upper mass or optionally also an intermediate mass between the upper mass and the lower mass. A corresponding cable can be provided for transmitting the electrical current.

Since no internal combustion engine is required for driving, noise and exhaust gas emissions can be reduced or excluded. This opens up additional fields of use, for example in closed rooms, tunnels and underground garages. The design according to the invention allows the reduction of the number of components necessary for the drive, for example a coupling, V-belt, pulley, seals and protective housings for the drive belt.

The running behavior of the unbalance exciter can be stabilized, since the direct connection of the electric motor eliminates rotational speed fluctuations due to a — belt drive.

8 EP3 862 487

These and other advantages and features of the invention are explained in more detail in the following using an example, with the assistance of accompanying figures. In the figures:

Fig. 1 shows a ground compaction device according to the invention in a side view;

Fig. 2 shows an unbalance exciter of the ground compaction device of Fig. 1 in a sectional view; and

Fig. 3 shows the unbalance exciter in a perspective sectional view.

Fig. 1 shows an example of a vibration plate serving as a ground compaction device.

The vibration plate has an upper mass 1 and a lower mass 2 movable relative to the upper mass 1. The lower mass 2 is coupled to the upper mass 1 via a rubber buffer 3 serving as a vibration decoupling device. In this way, the strong vibrations arising on the lower mass 2 are transmitted only damped to the upper mass 1.

The upper mass 1 has a support frame 4 on which a rechargeable battery 5 and a converter 6 are attached which are also assigned to the upper mass 1. The rechargeable battery 5 and the converter 6 are enclosed by a protective frame 7.

The rechargeable battery 5 is exchangeable and can be replaced by another rechargeable battery if necessary. For this purpose, a plug-in connector onto which the rechargeable battery 5 can be plugged is provided on the converter 6 or on the converter housing belonging to the converter 6.

The lower mass 2 has a ground contact plate 9, by means of which the ground underneath can be compressed. A vibration exciter or unbalance exciter 10 also associated with the lower mass 2 is arranged on the upper side of the ground contact plate 9.

In the prior art, unbalances of this kind are usually driven rotatably by motors, in particular internal combustion engines, which are arranged on the upper mass.

According to the invention, however, an electric motor (not shown in Fig. 1) is integrated directly into the unbalance exciter 10, as will be explained below.

9 EP3 862 487

In addition, a guide drawbar 11 is fastened to the upper mass 2 or the support frame 4 for guiding the vibration plate. A rotational speed lever (not shown) for influencing the motor speed of the electric motor serving as a drive motor can be provided on the guide drawbar 11. Depending on the embodiment, however, an on/off switch for switching on the electric motor explained below is sufficient.

In addition, a guide bar or control handle 12 is arranged on the upper end of the guide drawbar 11, via which the relative rotational position of the unbalance shafts in the unbalance exciter 10, in particular the phase position thereof relative to one another, can be adjusted as will be explained below. In this way, forward and backward travel of the vibration plate can be achieved in a manner known per se.

Arranged on the lower mass 2 or the ground contact plate 9 is a wheel assembly with two wheels 13 that are axially relative to each other. In the normal state shown in Fig. 1, the wheels 13 float above the ground. By tilting the vibration plate, it is however 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 tilting or transport state, the vibration plate can easily be moved and transported by means of the wheels 13.

Figs. 2 and 3 show the unbalance exciter 10 in a sectional plan view (Fig. 2) and in a perspective sectional view (Fig. 3). The figures will accordingly be explained together.

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 ground to be compacted.

Two unbalance shafts are rotatably mounted in the interior of the exciter housing 20, namely a drive unbalance shaft 21 serving as the first unbalance shaft and a second unbalance shaft 22.

The two unbalance shafts 21, 22 are rotatably coupled to one another in opposite directions. For this purpose, a gear pair is provided, with a first gear 23 mounted on the drive unbalance shaft 21 and a second gear 24 mounted on the second

10 EP3 862 487 unbalance shaft 22. The two gears 23, 24 mesh with one another, as shown in Fig. 2. In this way, a rotation of the drive unbalance shaft 21 is directly transferred into an opposite rotation of the second unbalance shaft 22.

The first unbalance shaft or drive unbalance shaft 21 bears a first unbalance mass 25 which is divided into two partial mass elements 25a, 25b. The two partial mass elements 25a, 25b are axially spaced apart from one another and arranged on the end-face ends of the drive unbalance shaft 21.

The second unbalance shaft 22 in turn bears a second unbalance mass 26 which is arranged as a single mass element approximately in the middle of the second unbalance shaft 22. However, the second unbalance mass 26 can also optionally be divided into a plurality of partial mass elements if this is expedient for reasons of space.

An electric motor 27 serving as a drive motor is arranged axially between the two partial mass elements 25a, 25b in the central region of the drive unbalance shaft 21. The electric motor 27 has a rotor 28 which is mounted directly on the drive unbalance shaft 21. For this purpose, a corresponding rotor seat 29 is provided on the drive unbalance shaft 21. Accordingly, the drive unbalance shaft also functions as a motor shaft for the electric motor 27.

For mounting and holding the rotor 28, it is of course also possible to provide additional components, such as a sleeve carrier or the like.

The rotor 28 is enclosed by a stator 30 which also belongs to the electric motor 27 and is mounted in a suitable manner in the exciter housing 20.

As a result of the arrangement of the electric motor 27 directly on the first unbalance shaft, which thereby fulfills the function of the drive unbalance shaft 21, the electric motor 27 is integrated directly and completely into the unbalance exciter 10. An external drive of the unbalance exciter 10, as is known from the prior art, is therefore not necessary. The unbalance exciter 10 forms an integral unit with the electric motor 27 and does not require any further drive from the outside.

11 EP3 862 487

The compact structure of the unbalance exciter 10 is also achieved in that the rotor 28 of the electric motor 27 rotates in a plane or an axial height which corresponds approximately to a rotational plane or axial height in which the unbalance mass 26 of the second unbalance shaft 22 rotates. The rotor 28 on the one hand and this unbalance mass 26 on the other hand then rotate at a height relative to one another, as Fig. 2 shows.

The unbalance shafts 21, 22 and the additional, in particular also rotating components are protected against effects from the outside by covers 31. The covers 31 can accordingly also be understood as part of the exciter housing 20.

In the torque coupling between the drive unbalance shaft 21 and the second unbalance shaft 22, a phase adjustment device 32 is provided in addition to the torque transmission via the two gearwheels 23, 24. The phase adjustment device 32 has an adjusting sleeve 33 which is arranged radially in the interior of the second gear 24 and is seated on the second unbalance shaft 22. The second unbalance shaft 22 can accordingly also be referred to as an adjusting shaft, since it is adjusted to change the phase position relative to the first unbalance shaft or drive unbalance shaft 21 with the aid of the phase adjustment device 32.

A sliding bearing is provided between the adjusting sleeve 33 and the second unbalance shaft 22 in order to ensure extremely reliable and easy rotation of the adjustment sleeve 33 relative to the second unbalance shaft 22.

The second unbalance shaft 22 (adjusting shaft) is designed as a hollow shaft. In its interior, a switching pin 34 is axially displaceable back and forth. The displaceability is effected with the aid of a piston 35 which is guided in a cylinder shaft 36. The piston chamber 37 enclosed by the piston 35 and the cylinder shaft 36 can be filled or emptied as required by a hydraulic fluid in order to effect the axial movement of the piston 35 and therefore of the switching pin 34.

A cylinder pin 38, which extends radially through the switching pin 34, is provided axially opposite the piston 35. The cylindrical pin 38 also extends through at least one longitudinal groove 39 formed in the second unbalance shaft 22, which is configured as a hollow shaft. Advantageously, two longitudinal grooves 39 are

12 EP3 862 487 provided opposite one another in the hollow wall of the second unbalance shaft 22 through which the cylinder pin 38 can extend.

The end faces of the cylinder pin 38 each engage in a helical groove (spiral groove 40) which is formed in the inner circumference of the adjusting sleeve 33. The spiral grooves 40 are Interlocked and extend opposite each other on the radial inner side of the adjusting sleeve 33.

In the event of an axial displacement of the switching pin 34, the cylindrical pin 38, which also moves axially and is secured against rotation relative to the second unbalance shaft 22 due to the longitudinal grooves 39, causes the adjustment sleeve 33 to rotate. Accordingly, the second gear wheel 24 is also rotated relative to the second unbalance shaft 22 so that the second unbalance mass 26 located on the second unbalance shaft 22, with respect to its rotational position, rotates relative to the first unbalance mass 25 or the partial mass elements 25a, 25b of the first unbalance shaft (drive unbalance shaft 21). In this way, the phase position of the unbalance shaft 21, 22, and therefore of the unbalance masses 25, 26, can be changed relative to one another. The axial movement of the cylinder pin 38 must only be a few millimeters in order to bring about the desired change in the phase position.

The described phase adjustment device 32 can of course also be realized on the first unbalance shaft or drive unbalance shaft 21 in order to be able to achieve the desired possibility of changing the phase position of the unbalance masses relative to one another.

In order to adjust the phase position, oil is in particular pumped into the cylinder shaft 36 and therefore into the piston chamber 37, and the piston 35 is pressed to the right until its stop. The pumping effect is generated, for example, by adjusting the control handle 12 in the drawbar head.

The resetting of the system is possible only during machine operation since, when the control handle 12 or the guide bar is actuated in the opposite direction, the pressure in the hydraulic system is released, and a return movement of the piston into its starting position takes place in that the unbalance shafts 22, 23 rotate against each other and, due to the inertia of the adjusting shaft (second unbalance

13 EP3 862 487 shaft 22), a restoring force is produced which is transmitted to the piston 35 via the adjusting sleeve 34 and pushes the piston 35 back.

When the two unbalance shafts 21, 22 rotate, the effect of the unbalance masses produces a resulting force vector, the direction of which is determined by the phase position of the unbalance masses. In this way, a directional effect of the unbalance exciter 10 can be achieved in order to guide the vibration plate or move it forward and backward.

Claims

1 EP3 862 487 SAHKOKAYTTOINEN TARYLEVY PATENTTIVAATIMUKSET1 EP3 862 487 PATENT CLAIMS

1. Maantiivistyslaite, jossa on - ylämassa (1); - ylämassaan (1) nähden liikkuva alamassa (2), jossa on maahan koskettava levy (9) maan tiivistämiseksi; - ylämassan (1) ja alamassan (2) välissä toimiva tärinänerotuslaite (3); - ainakin yksi alamassaan (2) kuuluva epätasapainon herätin (10) epätasapainovoiman kohdistamiseksi maahan koskettavaan levyyn (9); ja jossa on - alamassaan (2) aikaansaatu sähkömoottori (27) epätasapainon herättimen (10) käyttämiseksi; jolloin - sähkömoottori (27) on integroitu epätasapainon herättimeen (10); tunnettu siitä, että - epätasapainon herättimessä (10) on kaksi epätasapainoista akselia (21, 22), jotka on järjestetty toistensa kanssa yhdensuuntaisesti ja kytketty pyörimään keskenään vastakkaisiin suuntiin ja joissa on kulloinkin epätasapainoinen massa (25, 26).1. Soil compaction device with - upper mass (1); - a lower mass (2) moving relative to the upper mass (1) with a plate touching the ground (9) to compact the ground; - a vibration isolation device (3) operating between the upper mass (1) and the lower mass (2); - at least one unbalance exciter (10) belonging to the lower mass (2) for applying an unbalance force to the plate (9) touching the ground; and having - an electric motor (27) provided in the lower mass (2) for operating the unbalance exciter (10); wherein - the electric motor (27) is integrated with the unbalance exciter (10); characterized in that - the unbalance exciter (10) has two unbalanced shafts (21, 22) which are arranged parallel to each other and connected to rotate in mutually opposite directions and each time have an unbalanced mass (25, 26).

2. Patenttivaatimuksen 1 mukainen maantiivistyslaite, jolloin yksi epätasapainoisista akseleista on epätasapainoinen käyttöakseli (21) ja siinä on alue, joka muodostaa osan sähkömoottorista (27) siten, että epätasapainoinen käyttöakseli (21) on myös sähkömoottorin (27) moottoriakseli.2. Soil compaction device according to claim 1, wherein one of the unbalanced shafts is an unbalanced drive shaft (21) and has a region that forms part of the electric motor (27) such that the unbalanced drive shaft (21) is also the motor shaft of the electric motor (27).

3. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin kummankin epätasapainoisen akselin (21, 22) väliin on toiminnallisesti aikaansaatu vaiheensäätölaite (32) kummankin epätasapainoisen akselin (21, 22) vaiheasennon säätämiseksi suhteessa toisiinsa.3. A soil compaction device according to one of the previous claims, wherein a phase adjustment device (32) is functionally provided between both unbalanced axes (21, 22) to adjust the phase position of both unbalanced axes (21, 22) in relation to each other.

2 EP3 862 4872 EP3 862 487

4. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin sähkömoottorissa (27) on roottori (28), joka on järjestetty epätasapainoiselle käyttöakselille (21).4. Soil compaction device according to one of the preceding claims, wherein the electric motor (27) has a rotor (28) arranged on an unbalanced drive shaft (21).

5. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin sähkömoottorissa (27) on staattori (30), joka sulkee ainakin osittain sisäänsä epätasapainoiselle käyttöakselille (21) järjestetyn roottorin (28).5. Soil compaction device according to one of the preceding claims, wherein the electric motor (27) has a stator (30) which at least partially encloses the rotor (28) arranged on the unbalanced drive shaft (21).

6. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin - epätasapainoinen käyttöakseli (21) kannattelee kahta epätasapainoista massaa (25a, 25b), jotka ovat aksiaalisesti erillään toisistaan; ja jolloin - sähkömoottori (27) on järjestetty aksiaalisesti kummankin epätasapainoisen massan (25a, 25b) väliin.6. A soil compaction device according to one of the preceding claims, wherein - the unbalanced drive shaft (21) supports two unbalanced masses (25a, 25b), which are axially separated from each other; and wherein - the electric motor (27) is arranged axially between the two unbalanced masses (25a, 25b).

7. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin aksiaalisesti toisistaan erillään olevat epätasapainoiset massat (25a, 25b) on järjestetty epätasapainoisen käyttöakselin (21) päätysivupäihin.7. Soil compaction device according to one of the preceding claims, wherein the unbalanced masses (25a, 25b) that are axially separated from each other are arranged at the end side ends of the unbalanced drive shaft (21).

8. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin alamassaan (2) on aikaansaatu pyörämekanismi (13) maantiivistyslaitteen kuljettamiseksi tarpeen mukaan.8. Soil compaction device according to one of the preceding claims, wherein a wheel mechanism (13) is provided in the lower mass (2) for transporting the soil compaction device as needed.

9. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin ylämassaan (1) on aikaansaatu energiavarasto (5) sähkömoottorin (27) — syöttämiseksi sähköenergialla.9. A soil compaction device according to one of the preceding claims, wherein an energy storage (5) is provided in the upper mass (1) to supply the electric motor (27) with electrical energy.

10. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin ylämassaan (1) on aikaansaatu muunninlaite (6) energiavaraston (5) tuottaman sähkövirran muuntamiseksi sähkömoottorille (27) sopivaksi virraksi.10. A soil compaction device according to one of the preceding claims, wherein a converter device (6) is provided in the upper mass (1) to convert the electric current produced by the energy storage (5) into a current suitable for the electric motor (27).

11. Jonkin edellisen patenttivaatimuksen mukainen maantiivistyslaite, jolloin muunninlaitteessa (6) on kotelo, johon on aikaansaatu pistokeliitäntä energiavaraston (5) kytkemistä varten.11. A soil compaction device according to one of the preceding claims, wherein the converter device (6) has a housing to which a plug connection is provided for connecting the energy storage (5).