Imbalance Exciter for Soil Compaction Devices

Abstract

An unbalance exciter for a soil compaction device comprises at least two rotatable unbalance masses which are rotatably mounted in opposite directions relative to each other, and at least two rotors. Each of the unbalance masses is coupled to a respective one of the rotors. The at least two unbalance masses and the associated rotors are mounted coaxially relative to each other. A stator is associated with each of the rotors in such a way that each rotor and the associated stator form an electric motor.

Claims

1. An unbalance exciter for a soil compaction device, comprising: at least two rotatable unbalance masses which are mounted rotatably in opposite directions to one another; and at least two rotors; wherein a respective one of the unbalance masses is coupled to each of the rotors; the at least two unbalance masses and the associated rotors are mounted coaxially to one another; and wherein a stator is associated with each of the rotors, in such a way that each rotor and the associated stator form an electric motor.

2. The unbalance exciter according to claim 1, further comprising a control system is provided for the control of the electric motors and thus for adjusting and changing the phase position of the at least two unbalance masses relative to each other.

3. The unbalance exciter according to claim 1, wherein at least one of the stators surrounds only a circular segment of a circumference of the rotor assigned to the at least one stator.

4. The unbalance exciter according to claim 1, wherein at least one of the unbalance masses comprises two unbalance mass elements, each of which is laterally mounted on a respective end face of the associated rotor.

5. The unbalance exciter according to claim 1, further comprising an axle, and wherein the unbalance masses are mounted together with the associated rotors on the axle so as to be rotatable in opposite directions.

6. The unbalance exciter according to claim 1, wherein each of the unbalance masses and its associated rotor is mounted on its own axle element.

7. The unbalance exciter according to claim 1, wherein each of the rotors is coupled to an axle element which is rotatably mounted in a mounting device.

8. The unbalance exciter according to claim 7, wherein the mounting device, the axle element, the stator, the rotor, and the unbalance mass coupled to the rotor form an exciter unit.

9. A soil compaction device, comprising: an upper mass; a bottom mass that is movable relative to the upper mass, the bottom mass including a soil contact plate for soil compaction; a vibration decoupling device acting between the upper mass and the bottom mass; and an unbalance exciter associated with the bottom mass and being configured to apply an unbalance force to the soil contact plate, the unbalance exciter including. at least two rotatable unbalance masses which are mounted rotatably in opposite directions to one another; and at least two rotors; wherein a respective one of the unbalance masses is coupled to each of the rotors; the at least two unbalance masses and the associated rotors are mounted coaxially to one another; and wherein a stator is associated with each of the rotors, in such a way that each rotor and the associated stator form an electric motor.

10. A soil compaction device according to claim 9, wherein the unbalance exciter comprises at least two exciter units mounted on the soil contact plate; and wherein the exciter units are arranged relative to each other on the soil contact plate in such a way that the rotors of the two exciter units are arranged coaxially relative to each other on a common virtual rotational axle and are rotatable in opposite directions relative to each other.

11. The soil compaction device according to claim 9, further comprising a control system that is configured to adjust, in a desired manner, a phase position of the rotors and, thereby, the unbalance masses in the exciter units.

12. The soil compaction device according to claim 9, wherein at least one of the stators surrounds only a circular segment of a circumference of the rotor assigned to the at least one stator.

13. The soil compaction device according to claim 9, wherein at least one of the unbalance masses comprises two unbalance mass elements, each of which is laterally mounted on a respective end face of the associated rotor.

14. The soil compaction device according to claim 9, further comprising an axle, and wherein the unbalance masses are mounted together with the associated rotors on the axle so as to be rotatable in opposite directions.

15. The soil compaction device according to claim 9, wherein each of the unbalance masses and its associated rotor is mounted on its own axle element.

16. The soil compaction device according to claim 9, wherein each of the rotors is coupled to an axle element which is rotatably mounted in a mounting device.

17. The soil compaction device according to claim 16, wherein the mounting device, the axle element, the stator, the rotor, and the unbalance mass coupled to the rotor form an exciter unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] These and other advantages and features of the invention are elucidated in more detail below on the basis of examples with reference to the accompanying figures. Wherein:

[0043] FIG. 1 shows a schematic top view of an unbalance exciter with two rotors according to the invention;

[0044] FIG. 2 shows a variant of FIG. 1;

[0045] FIG. 3 shows a schematic top view of an exciter unit which may be used in the unbalance exciter according to the invention;

[0046] FIG. 4 shows an example of an exciter unit in perspective view;

[0047] FIG. 5 shows the exciter unit of FIG. 4 in side view;

[0048] FIG. 6 shows a variant to the unbalance exciters in FIG. 1 and FIG. 2;

[0049] FIG. 7 shows a schematic top view of an example of a soil compaction device;

[0050] FIG. 8 shows a variant for an unbalance exciter with four rotors;

[0051] FIG. 9 shows a variant to the unbalance exciter of FIG. 8;

[0052] FIG. 10 to FIG. 12 show further variants to the unbalance exciter of FIG. 8;

[0053] FIG. 13 shows an explanation of the centrifugal force effects during operation of the unbalance exciter of FIG. 2;

[0054] FIG. 14 shows an explanation of the centrifugal force effects during operation of the unbalance exciter of FIG. 9; and

[0055] FIG. 15 shows an explanation of the centrifugal force effects during an operation of the unbalance exciter of FIG. 11.

DETAILED DESCRIPTION

[0056] FIG. 1 shows a soil compaction device with two rotors 1, which are mounted to rotate in opposite directions on a common rotational axle 2. The rotational axle 2 may itself be fixed, which is to say, it does not need to be rotatably mounted. The decisive factor is that the rotors 1 are rotatable in opposite directions to each other, which is to say, in opposite directions of rotation.

[0057] Rotation of the rotors 1 is brought about by two stators 3 arranged on one side of the rotors 1.

[0058] A stator 3 forms an electric motor in conjunction with its associated rotor 1. A control system that is not shown is provided to control each electric motor, which control system is also capable of precisely ascertaining and influencing the respective angular or rotational position of the rotors 1.

[0059] In the example shown, the stators 3 do not thereby completely enclose the rotors 1 at the circumference, but rather only partially about a circular segment with a certain angle of lesser than 360°. In so doing, considerable installation space can be saved.

[0060] An example of how stators cover only one circular segment on the circumference of a rotors is known from DE 10 2020 100 842 A1.

[0061] Unbalance masses 4, which may be formed by a plurality of unbalance mass elements, are respectively attached to the end faces of the rotors 1. The unbalance mass elements may, in particular, be in the form of metal sheets which are fastened to the end faces of the rotors 1, which is to say, laterally, and thus form an unbalance mass 4 for each rotor 1 in its entirety.

[0062] “Unbalance mass” in this context means that an eccentric mass is provided on the rotor 1 which eccentric mass provokes a centrifugal force during rotation.

[0063] The rotational axle 2 is supported by bearings 5 in a housing that is not shown or on a soil contact plate that is not shown.

[0064] Since the control system for the individual electric motors provided for the rotors 1 and stators 3 is designed in such a way that it may influence not only the rotational speed of the rotors 1 but rather also precisely the respective angular position of the rotors 1, and thus the phase position or rotational position of the rotors 1 relative to one another, the centrifugal force vectors generated by the unbalance masses 4 when the two rotors 1 rotate may be precisely set relative to one another.

[0065] The rotors 1 are, in particular, rotatable in opposite directions to each other such that—depending on the setting—partial components of the centrifugal force vectors may add up or compensate for each other. This will be explained again later.

[0066] The direction of rotation of the rotors 1 is shown by double arrows, wherein during operation different directions of rotation of the two rotors 1 are respectively to be achieved.

[0067] FIG. 2 shows a variant to FIG. 1 in which the stators 3 are mounted on different sides in order to save installation space. In addition, the mounting of the rotational axle 2 may be simplified in this variant inasmuch as the middle bearings 5 are omitted in contrast to the design of FIG. 1.

[0068] FIG. 3 shows a portion of the unbalance exciter of FIG. 1 and FIG. 2 as a single unit. In this variant, it is possible to divide an unbalance exciter into a plurality of partial exciters 6 or alternatively exciter units. FIG. 3 shows such a partial exciter 6. By way of example, two of the partial exciters 6 shown in FIG. 3 may form an exciter of the type shown in FIG. 1 or FIG. 2, if the two partial exciters 6 of FIG. 3 are combined. Here, too, it is desirable that two rotational axles 2 are then coaxial with each other, which is to say, on a common virtual rotational axle, such that the arrangement of FIG. 1 may be achieved.

[0069] FIG. 4 shows an example of a partial exciter 6 shown only schematically in FIG. 3. FIG. 5 shows the partial exciter in a side view.

[0070] The bearings 5 are inserted in two stable side panels 7, which form a mounting device. The bearings 5 rotatably accommodate the rotational axle 2. The rotor 1 is held on the rotational axle 2 and may be coupled to the rotational axle 2, for example, by means of a shaft-hub connection. Likewise, it is also possible that a bearing is provided in the hub of the rotor 1, by means of which the rotor 1 is rotatably mounted on the rotational axle 2. The rotational axle 2 then no longer needs to be rotatably mounted in the side panels 7 but may be held rigidly in the side panels 7.

[0071] The unbalance mass elements 4a are fastened to the end faces of the rotor 1 and together form the unbalance mass 4. It is clearly visible in FIG. 4 that the unbalance mass 4 is formed by a plurality of sheet metal elements which are fastened together to the end faces of the rotor 1.

[0072] The stator 3 is arranged on the outer circumference of the rotor 1. In so doing, the stator 3 does not extend over the entire circumference of the rotor 1, but rather only over a partial circumference, which is to say, over a circular segment. In the present example, the stator 3 extends over an angle of approximately 90° and has three stator poles 3a, of which only two are visible in FIG. 4 and FIG. 5.

[0073] FIG. 6 shows a schematic top view of an arrangement similar to FIG. 1, wherein two stators 3 are however provided for each rotor 1. By providing two stators 3 for each rotor 1, a particularly efficient powerful electric motor may be achieved.

[0074] FIG. 7 shows a schematic top view of a vibratory plate serving as a soil compaction device.

[0075] The basic construction of such a vibratory plate is known and is shown, for example, in FIG. 1 of DE 10 2020 100 842 A1.

[0076] The vibratory plate of FIG. 7 has a soil contact plate 8, upon which the unbalance exciter of FIG. 2 is arranged.

[0077] The soil contact plate 8 and the unbalance exciter with the rotors 1, the stators 3, and the rotational axle 2 together form a bottom mass 9.

[0078] A partially illustrated upper mass 10 is arranged in the drawing plane seen above the bottom mass 9, which upper mass has a guide drawbar 11 and an operator handle 12. An operator may accordingly steer and guide the entire vibratory plate by grasping the guide handle 12, shown only schematically, via the guide drawbar 11. The upper mass 10 may have further components, for example, a battery as energy storage for the operation of the electric motors as well as corresponding housing or frame components for bearing the battery and for fastening the guide drawbar 11, which however are not shown in FIG. 7.

[0079] The upper mass 10 is vibration-decoupled from the bottom mass 9 by means of a corresponding vibration-decoupling device, which is not shown. This device may, for example, be rubber buffers.

[0080] FIG. 8 shows an unbalance exciter with a total of four rotors 1, which are arranged coaxially to each other and are rotatably mounted on a common rotational axle 2. Each of the rotors 1, together with an associated stator 3, forms its own electric motor.

[0081] The direction of rotation of the rotors 1 may be set by accordingly controlling the stators 3. In the present example, the two outer rotors 1 rotate upward, whereas the two inner rotors 1 rotate downward (cf. direction of arrow).

[0082] FIG. 9 is a variant of FIG. 8, in which two of the stators 3 are arranged opposite each other, similar to the soil compaction device of FIG. 2. In this way, here too a compact construction may also be achieved.

[0083] FIG. 10 is another variant in which the rotational axle 2 is mounted only at its outer ends by means of bearings 5, whereas on the inside, between the rotors 1, no bearings are provided, unlike in FIG. 8 and FIG. 9.

[0084] FIG. 11 shows a schematic top view of a further variant in which the two inner rotors 1 are combined to form a common rotor 1, however with double the mass, in particular double the unbalance mass 4. Accordingly, the associated stator 3 is also larger or alternatively extends over a greater width in order to be able to drive the centrally located rotor 1, which weighs twice as much, in rotation. In this, the reference to the mass of the rotor 1 substantially refers to the unbalance mass 4, so that the inner rotor 1 bears an unbalance mass 4 that is twice as large as the unbalance mass 4 of the outer rotor 1.

[0085] FIG. 12 shows a further variant in which two opposing stators 3 are provided for each rotor 2.

[0086] FIG. 13 explains the mode of operation of the unbalance exciter shown by way of example in FIG. 2.

[0087] The unbalance exciter comprises two exciter units A and B, with rotors 1, which are mounted on a common rotational axle 2. Unbalance masses 4 in the form of partial unbalance masses are attached to the end faces of the rotors 1.

[0088] The middle image section of FIG. 13 shows respective positions of the rotors 1 by way of example, with the unbalance masses 4 borne by them.

[0089] Line a) shows a position in which the unbalance masses 4 of the exciter units A and B are respectively at the top at the same time. The centrifugal force vectors F are shown in the right image part of line a). Since the unbalance masses 4 are at the top, the centrifugal force vectors F of the two exciter units A, B are correspondingly also directed upwards.

[0090] When the two rotors 1 each perform a 180° rotation, the unbalance masses 4 also rotate 180° in opposite directions. The resulting horizontal components of the centrifugal force vectors F cancel each other out, whereas the vertical components add up, as is shown by a resulting force vector 15 (double arrow to the left of the representation of the centrifugal force vectors F).

[0091] In line b) of FIG. 13, the phase position of the two rotors 1 and thereby of the unbalance masses 4 has been changed with the aid of the control system, such that the two unbalance masses 4 that are rotatable in opposite directions are now at an angle of about 45° to the top left. Correspondingly, the centrifugal force vectors F are also directed, as shown in the right image part of line b).

[0092] In this case, the horizontal components of the centrifugal force vectors may also at least partially add up, whereby the resulting force vector 15 is tilted obliquely to the left.

[0093] In line c), a position of the rotors 1 is shown in which the phase position has been changed in such a way that the unbalance masses 4 are rotated in the representation shown there upwards to the right at an angle of about 45°. Correspondingly, the centrifugal force vectors F are also rotated to the upper right and consequently the resulting force vector 15 is also rotated to the upper right.

[0094] FIG. 14 shows an example of an unbalance exciter with exciter units A, B, C and D, which was elucidated previously on the basis of FIG. 10. Various rotational positions of rotors 1 and unbalance masses 4 are here too shown to illustrate the effects on the centrifugal force vectors F and the thereby resulting force vectors 15.

[0095] In line a) of FIG. 14, the respective positions of the rotors 1 and unbalance masses 4 that are rotatable in opposite directions are shown by way of example for the exciter units A and D on the one hand as well as the exciter units B and C on the other hand.

[0096] In lines b) and c) of FIG. 14, further positions are shown analogously to FIG. 13.

[0097] FIG. 15 shows the unbalance exciter of FIG. 11, with exciter units A, B and C. In lines a) to c), in a manner analogous to FIG. 13 and FIG. 14, corresponding examples are shown for rotational positions of the rotors 1 and unbalance masses 4, rotatable together in the same direction (exciter units A, C) and—with unbalance mass 4 twice as large—rotatable in opposite directions (exciter unit B).