EP3862487B1 - Vibration plate with electric drive - Google Patents

Description

The invention relates to a soil compacting device, in particular a vibrating plate or vibrating plate.

Such soil compacting devices or vibrating 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.

In known vibrating plates, a drive in the form of an internal combustion engine is provided on the upper mass. In addition, a drawbar with a guide bracket can be attached to the upper mass, with the help of which the operator controls the vibration plate. An imbalance exciter is provided on the lower mass, which is used to generate vibrations which are introduced into the soil to be compacted via a soil contact plate also provided on the lower mass.

Especially with small and medium-sized vibrating plates, the power of the drive motor is transmitted to the unbalance exciter on the unbalance mass with the help of a belt drive. In addition, a centrifugal clutch can be flanged onto the internal combustion engine serving as the drive motor, so that the imbalance exciter is still decoupled from the engine at low engine speeds.

The imbalance exciter itself often has two counter-rotating imbalance shafts arranged parallel to one another, each of which carries eccentrically arranged weights (imbalance masses) in order to be able to achieve the desired vibrations when the imbalance shafts rotate.

The direction of a resulting force vector can be changed by changing the phase position of the unbalanced shafts relative to one another, in particular by changing the angular position of the unbalanced shafts and thus the respective unbalanced masses relative to one another. In this way, reversibility of the vibrating plate is possible, so that the vibrating plate can be moved forwards and backwards. In addition, a stationary vibration can also be achieved.

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

When such a vibration plate is in operation, the belt drive is heavily loaded. This is due in particular to the fact that the relative position of the two belt pulleys on the upper mass and on the lower mass is constantly changing due to the strong vibrations. In particular, the distance between the pulleys and their parallelism can vary, which increases the load on the drive belt. In addition, the elongation of the belt during operation can result in slippage, which leads to speed fluctuations on the imbalance exciter. Due to the increased wear on the drive belt, the maintenance effort also increases.

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

From the DE 10 2017 121 177 A1 a soil compacting device is known, with an upper mass and a lower mass which is elastically coupled to the upper mass and has a soil contact plate. A vibration exciter, which is driven by an electric motor, is arranged on the ground contact plate. The unbalanced masses of the vibration exciter can be an integral part of the motor shaft of the electric motor.

In the DE 11 2016 000 636 T5 describes a vibration compactor that can be used on a road roller, with a vibrating device that is arranged in a roller drum. The vibration device has a shaft and three eccentric masses. A motor is provided for each eccentric mass to rotate the masses about the shaft.

The invention is based on the object of specifying an improved soil compacting device in which the disadvantages of the prior art can be avoided.

The object is achieved according to the invention by a soil compacting device having the features of claim 1 . Advantageous configurations are specified in the dependent claims.

A soil compacting device is specified, with an upper mass, with a lower mass that can be moved relative to the upper mass, with a soil contact plate for soil compaction, with a vibration decoupling device acting between the upper mass and the lower mass and with at least one unbalance exciter belonging to the lower mass for applying an unbalance force to the soil contact plate. An electric motor for driving the imbalance exciter is provided on the lower mass, the electric motor being integrated into the imbalance exciter.

Such a soil compacting device can in particular be a vibrating plate or vibrating plate, with which soil can be effectively compacted or stones can be shaken into a soil.

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

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

For this purpose, the imbalance exciter has two imbalance shafts which are arranged parallel to one another and are coupled to rotate in opposite directions, each of which carries an imbalance mass. The two unbalanced shafts can be coupled, for example, by means of a pair of gears carried by the unbalanced shafts.

Such a structure is known per se for imbalance exciters and has proven itself in practice in many ways. In contrast to the imbalance exciters known from the prior art, however, the drive motor (electric motor) is integrated into the imbalance exciter according to the invention.

A resultant force vector is generated by the unbalanced shafts rotating in opposite directions, the alignment of which is determined depending on the relative rotational position of the unbalanced masses or eccentrics to one another. The oscillating force vector changes amount and sign or direction with the rotation of the imbalance shafts and thus causes a force which, depending on the oscillation phase, is directed upwards and lifts the ground contact plate slightly off the ground or - after 180° rotation - is directed downwards and can be introduced into the soil to be compacted via the soil contact plate.

One of the unbalanced shafts can be designed as an unbalanced drive shaft and have an area that forms part of the electric motor, such that the unbalanced drive shaft is also the motor shaft of the electric motor. In this way, the electric motor can be integrated particularly efficiently into the imbalance exciter.

In this respect, the drive unbalanced shaft can also be referred to as the first unbalanced shaft of the two unbalanced shafts of the unbalanced exciter. It can particularly advantageously be designed in one piece, so that it has areas that carry the unbalanced mass or eccentric, and has areas that are part of the electric motor.

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

Effectively, a phase adjustment device can be provided between the two unbalanced shafts to adjust the phase position of the two unbalanced shafts relative to one another. By adjusting the phase position of the two unbalanced shafts and thus also the unbalanced masses carried by the unbalanced shafts, the alignment of the resulting force vector can be adjusted.

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

In order to rotationally couple the two unbalanced shafts to one another and thus cause the two unbalanced shafts to rotate in opposite directions, two meshing gears can be provided between the two unbalanced shafts, with the rotational position of one of the gears being able to be changed by the adjustment sleeve assigned to this gear relative to the unbalanced shaft carrying this gear, to effect the phase shift.

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

With the help of the phase adjustment device, it is thus possible to change the alignment of the resulting force vector and, for example, to bring about a reversal of direction (reversal).

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

Furthermore, the electric motor can have a stator which at least partially encloses the rotor arranged on the unbalanced drive shaft. The Accordingly, the stator can be arranged directly in the housing of the imbalance exciter and carried by the imbalance exciter housing.

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

The unbalanced drive shaft can carry two unbalanced masses spaced apart axially from one another, with the electric motor being arranged axially between the two unbalanced masses. In this case, the rotor in particular can be arranged axially between the two unbalanced masses.

In one embodiment, the unbalanced masses, which are spaced apart axially from one another, can be arranged on the front ends of the unbalanced drive shaft. In this way, a very compact design of the imbalance shaft can be implemented. In addition, by arranging the two unbalanced masses at the two front ends, the space between them can be made available completely for the electric motor, with the stator and rotor.

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

A wheel device can be provided on the lower mass for transporting the soil compacting 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 operation, the wheels can be detached from the ground and, as it were, hover above the ground. By tilting the soil compacting device, the wheels can be brought into contact with the soil in order to displace the soil compacting device with the aid of the wheel means.

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

An energy store can be provided on the upper mass to supply the electric motor with electrical energy. The energy store can in particular be an electric battery. The 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 an appropriate power pack, or outside it in a charging station to be provided for this purpose or also via a power pack.

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

A converter device can be provided on the upper mass for converting an electrical current provided by the energy store into a current suitable for the electric motor. In order to achieve vibrations and vibration frequencies that are advantageous for soil compaction, it is necessary for the electric motor to reach a corresponding speed. In order to achieve this speed, it is advantageous if the motor, which is designed as an asynchronous machine, for example, receives a power supply with a corresponding frequency that differs from the frequency of the public grid (50 Hz). Accordingly, the converter is provided in order to provide a current with a higher frequency. In addition, however, the voltage can also be adjusted 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 store is provided. Accordingly, it is easily possible to insert the energy store into the plug connection or—after use—to remove it from the plug connection. It is also possible for a corresponding mount or support to be provided on the housing of the converter device, so that the energy store can be reliably mounted on the housing of the converter device.

The imbalance exciter thus specified can accordingly be constructed in a very compact manner. In particular, it has the electric motor with the drive unbalanced shaft as the first unbalanced shaft, and the second unbalanced shaft, into which the phase adjustment device can be integrated.

The imbalance exciter forms an integral unit with the electric motor and requires no further external drive.

The drive motor known in the prior art is thus replaced by an electric motor that sits directly on one of the imbalance shafts. The unbalanced masses on the second unbalanced shaft are entrained via a gear with an interposed phase adjustment device. Is on the upper mass or possibly also an intermediate mass between the upper mass and the lower mass the battery is intended as an energy store. A corresponding cable can be provided for the transmission of the electrical current.

Because no internal combustion engine is required for the drive, noise and exhaust emissions can be reduced or eliminated. This opens up additional areas of application, for example in closed rooms, tunnels and underground car parks. The structure according to the invention allows the number of components required for the drive to be reduced, for example the clutch, V-belt, pulley, seals and protective housing for the drive belt.

The running behavior of the unbalance exciter can be stabilized because the direct connection of the electric motor eliminates speed fluctuations caused by a belt drive.

Fig. 1

eine erfindungsgemäße Bodenverdichtungsvorrichtung in Seitenansicht;

Fig. 2

einen Unwuchterreger der Bodenverdichtungsvorrichtung von Fig. 1 in Schnittdarstellung; und

Fig. 3

den Unwuchterreger in perspektivischer Schnittdarstellung.

These and other advantages and features of the invention are explained in more detail below using an example with the aid of the accompanying figures. Show it:

1

a soil compaction device according to the invention in side view;

2

an imbalance exciter of the soil compaction device from 1 in sectional view; and

3

the imbalance exciter in a perspective sectional view.

1 Fig. 12 shows an example of a vibrating plate serving as a soil compacting device.

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 coupled to the upper mass 1 via rubber buffers 3 serving as a vibration decoupling device. In this way, the strong vibrations occurring on the lower mass 2 are transmitted to the upper mass 1 only in a damped manner.

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

The battery 5 is exchangeable and can be replaced by 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.

The lower mass 2 has a ground contact plate 9, with the help of which the ground underneath can be compacted. A vibration exciter or imbalance exciter 10 which also belongs to the lower mass 2 is arranged on the upper side of the ground contact plate 9 .

In the prior art, such imbalance exciters are mostly driven in rotation by motors, in particular by internal combustion engines, which are arranged on the upper mass. According to the invention, however, an in 1 not shown electric motor integrated directly into the imbalance exciter 10, as will be explained below.

In order to guide the vibration plate, a guide pole 11 is also attached to the upper mass 2 or the support frame 4 . A speed lever (not shown) for influencing the engine speed of the electric motor serving as the drive motor can be provided on the guide pole 11 . Depending on the embodiment, however, an on/off switch is also sufficient for switching on the electric motor, which will be explained later.

In addition, a guide bar or control handle 12 is arranged at the upper end of the guide pole 11, via which the relative rotational position of the imbalance shafts in the imbalance exciter 10, in particular their phase relationship to one another, can be adjusted, as will be explained later. In this way, the vibrating plate can be moved forwards and backwards in a manner known per se.

On the lower mass 2 or the ground contact plate 9 there is a wheel device with two wheels 13 which are axial to one another. in the in 1 shown normal state, the wheels 13 float 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 lifts off the ground completely. In this tilted or transport state, the vibrating plate can be easily moved and transported using the wheels 13 .

The 2 and 3 show the imbalance exciter 10 in a sectional plan view ( 2 ) and in a perspective sectional view ( 3 ). Accordingly, the figures are explained together.

The imbalance exciter 10 has an exciter housing 20 which, like 1 shows, is applied directly to the ground contact plate 9 in order to optimally initiate the vibrations generated by the imbalance exciter 10 in the ground contact plate 9 and thus the soil to be compacted.

Inside the exciter housing 20, two unbalanced shafts are rotatably mounted, namely a drive unbalanced shaft 21 serving as the first unbalanced shaft and a second unbalanced shaft 22.

The two imbalance shafts 21, 22 are coupled to rotate in opposite directions to one another. For this purpose, a gear pair is provided, with a mounted on the drive unbalanced shaft 21 first gear 23 and mounted on the second unbalanced shaft 22 second gear 24. The two gears 23, 24 mesh with each other, such as 2 shows. In this way, a rotation of the drive unbalanced shaft 21 is directly transferred to an opposite rotation of the second unbalanced shaft 22 .

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

The second unbalanced shaft 22 in turn carries a second unbalanced mass 26 which is arranged as a single mass element approximately in the middle of the second unbalanced shaft 22 . However, the second unbalanced mass 26 can also be divided into a plurality of partial mass elements if this makes sense for reasons of installation space.

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

Additional components, such as a sleeve carrier or the like, can of course also be provided for mounting and holding the rotor 28 .

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

By arranging the electric motor 27 directly on the first unbalanced shaft, which thereby fulfills the function of the drive unbalanced shaft 21 , the electric motor 27 is directly and completely integrated into the unbalanced exciter 10 . A drive of the imbalance exciter 10 from the outside, as is known from the prior art, is therefore not necessary. The imbalance exciter 10 forms an integral unit with the electric motor 27 and requires no further external drive.

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 that corresponds approximately to a plane of rotation or axial height in which the unbalanced mass 26 of the second unbalanced shaft 22 rotates. The rotor 28 on the one hand and this unbalanced mass 26 on the other hand then consequently rotate against each other at a height such as 2 shows.

The imbalance shafts 21, 22 and the other, in particular rotating components are protected by covers 31 against external influences. Accordingly, the covers 31 can also be understood as part of the exciter housing 20 .

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

A sliding bearing is provided between the adjustment sleeve 33 and the second unbalanced shaft 22 in order to ensure that the adjustment sleeve 33 is rotated as reliably and easily as possible relative to the second unbalanced shaft 22 .

The second imbalance shaft 22 (adjusting shaft) is designed as a hollow shaft. In its interior, a shift pin 34 can be moved back and forth axially. The displaceability is brought about 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 with hydraulic fluid as required in order to bring about the axial movement of the piston 35 and thus of the shift pin 34 .

A cylindrical pin 38 is provided axially opposite the piston 35 and extends radially through the shift bolt 34 . The cylinder pin 38 also extends through at least one longitudinal groove 39, which is designed in the second imbalance shaft 22 designed as a hollow shaft. It makes sense to provide two longitudinal grooves 39 opposite one another in the hollow wall of the second imbalance shaft 22, through which the cylindrical pin 38 can extend.

The end faces of the cylinder pin 38 each engage in a spiral groove (spiral groove 40) which is formed on the inner circumference of the adjusting sleeve 33. The spiral grooves 40 are intertwined and each extend opposite one another on the radial inside of the adjustment 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 unbalanced shaft 22 due to the longitudinal grooves 39, causes a rotation of the adjusting sleeve 33. Accordingly, the second gear wheel 24 is also rotated relative to the second unbalanced shaft 22, so that the second unbalanced mass 26 located on the second unbalanced shaft 22 rotates in terms of its rotational position relative to the first unbalanced mass 25 or the partial mass elements 25a, 25b of the first unbalanced shaft (unbalanced drive shaft 21). In this way, the phase position of the unbalanced shaft 21, 22 and thus of the unbalanced masses 25, 26 can be changed in relation to one another. The axial movement of the cylinder pin 38 only has to be a few millimeters in order to bring about the desired change in the phase position.

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

To adjust the phase position, in particular oil is pumped into the cylinder shaft 36 and thus into the piston chamber 37 and the piston 35 up to its pushed to the right. The pumping effect is generated, for example, by adjusting the control handle 12 in the tiller head.

The system can only be reset during machine operation, since when the control handle 12 or guide bar is actuated in the opposite direction, the pressure in the hydraulic system is released and the piston 35 moves back into its starting position, with the imbalance shafts 22, 23 rotating in opposite directions and due to the inertia of the adjusting shaft (second imbalance shaft 22), a restoring force is brought about, which is transmitted to the piston 35 via the adjusting sleeve 34 and pushes the piston 35 back.

When the two unbalanced shafts 21, 22 rotate, the effect of the unbalanced masses results in a resultant force vector, the direction of which is determined by the phase position of the unbalanced masses. In this way, a directional effect of the unbalance exciter 10 can be achieved in order to steer the vibrating plate or to drive it forwards and backwards.

Claims (11)

1. Ground compaction device, comprising

   - an upper mass (1);

   - a lower mass (2) which is movable relative to the upper mass (1), comprising a ground contact plate (9) for ground compaction;

   - a vibration decoupling device (3) acting between the upper mass (1) and the lower mass (2);

   - at least one unbalance exciter (10) associated with the lower mass (2) for applying an unbalance force to the ground contact plate (9); and comprising

   - an electric motor (27) provided on the lower mass (2) for driving the unbalance exciter (10); wherein

   - the electric motor (27) is integrated in the unbalance exciter (10);

   characterised in that.

   - the unbalance exciter (10) has two unbalance shafts (21, 22) which are disposed in parallel with one another and are coupled so as to be able to rotate in opposite directions to one another and which each carry an unbalance mass (25, 26).
2. Ground compaction device as claimed in claim 1, wherein one of the unbalance shafts is a drive unbalance shaft (21) and has a region which forms a part of the electric motor (27), such that the drive unbalance shaft (21) is also a motor shaft of the electric motor (27).
3. Ground compaction device as claimed in any one of the preceding claims, wherein a phase adjusting device (32) is provided operatively between the two unbalance shafts (21, 22) in order to adjust the phase position of the two unbalance shafts (21, 22) with respect to one another.
4. Ground compaction device as claimed in any one of the preceding claims, wherein the electric motor (27) comprises a rotor (28) disposed on the drive unbalance shaft (21).
5. Ground compaction device as claimed in any one of the preceding claims, wherein the electric motor (27) has a stator (30) which at least partially surrounds the rotor (28) which is disposed on the drive unbalance shaft (21).
6. Ground compaction device as claimed in any one of the preceding claims, wherein

   - the drive unbalance shaft (21) carries two axially mutually spaced-apart unbalance masses (25a, 25b); and wherein

   - the electric motor (27) is disposed axially between the two unbalance masses (25a, 25b).
7. Ground compaction device as claimed in any one of the preceding claims, wherein the axially mutually spaced-apart unbalance masses (25a, 25b) are disposed at the end-face ends of the drive unbalance shaft (21).
8. Ground compaction device as claimed in any one of the preceding claims, wherein a wheel assembly (13) is provided on the lower mass (2) in order to transport the ground compaction device as required.
9. Ground compaction device as claimed in any one of the preceding claims, wherein an energy storage device (5) is provided on the upper mass (1) in order to supply the electric motor (27) with electrical energy.
10. Ground compaction device as claimed in any one of the preceding claims, wherein a converter device (6) is provided on the upper mass (1) in order to convert an electric current provided by the energy storage device (5) into a current suitable for the electric motor (27).
11. Ground compaction device as claimed in any one of the preceding claims, wherein the converter device (6) comprises a housing, on which a plug-in connection is provided for plugging in the energy storage device (5).

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