Vibration exciter for steerable soil compacting devices

Abstract

A vibration exciter for a soil compacting device, comprising a first unbalanced shaft, a second unbalanced shaft, which is arranged axially parallel to the first unbalanced shaft and which is contra-directionally rotatably coupled to the first unbalanced shaft in a form-locked manner, and a drive device for rotatably driving one of the two unbalanced shafts. The second unbalanced shaft has a first unbalanced shaft half and a second unbalanced shaft half, which is arranged coaxially to the first unbalanced shaft half and which can rotate relative to the first unbalanced shaft half. At least one respective unbalanced mass is arranged on the first unbalanced shaft, on the first unbalanced shaft half, and on the second unbalanced shaft.

Claims

1. A vibration exciter for a ground compaction device, comprising: a first imbalance shaft, a second imbalance shaft which is arranged axially parallel to the first imbalance shaft and which is coupled to the first imbalance shaft in a positively locking fashion so as to rotate in the opposite direction as the first imbalance shaft, wherein the second imbalance shaft is formed from a first imbalance shaft half and a second imbalance shaft half which is arranged coaxially with respect to the first imbalance shaft half and which is rotatable relative to the first imbalance shaft half, a drive device which is configured to drive one of the imbalance shafts in rotation, and a coupling device which couples the first imbalance shaft half and the second imbalance shaft half together in a positively locking fashion and so as to be rotatable relative to one another, the coupling device comprising a sleeve having opposed ends into which the first and second imbalance shaft halves and first and second traverse pins are inserted, wherein each of the first and second transverse pins engages the sleeve and a respective one of the first and second imbalance shaft halves; wherein at least one imbalance mass is arranged on each of the first imbalance shaft, the first imbalance shaft half, and the second imbalance shaft half.

2. The vibration exciter as claimed in claim 1, further comprising a relative-rotation device which is configured to rotate the first imbalance shaft half relative to at least one of the second imbalance shaft half and the coupling device.

3. The vibration exciter as claimed in claim 1, wherein the first imbalance shaft and the second imbalance shaft are coupled to one another by way of the coupling device so as to rotate in opposite directions.

4. The vibration exciter as claimed in claim 1, wherein the sleeve device has, on an outer side thereof, a gearwheel device that is configured to engage into a further gearwheel device which is coupled to the first imbalance shaft.

5. The vibration exciter as claimed in claim 2, wherein the relative-rotation device comprises the first transverse pin which is arranged on the first imbalance shaft half, which can be displaced axially with respect to the first imbalance shaft half by a control slide, and which is configured to engage in a positively locking fashion into 1) a recess of the first imbalance shaft half and 2) a recess of at least one of the coupling device and the sleeve device, wherein at least one of the recesses has a groove which runs helically at least in sections thereof, and wherein the control slide is configured to be displaced by way of at least one of an actuation device and a piston/cylinder unit.

6. The vibration exciter as claimed in claim 5, wherein the first imbalance shaft half has a cavity, and the control slide and the actuation device are arranged within the cavity.

7. The vibration exciter as claimed in claim 1, wherein a further relative-rotation device is provided that comprises the second transverse pin which is arranged on the second imbalance shaft half, which can be displaced axially with respect to the second imbalance shaft half by a further control slide, and which is configured to engage in a positively locking fashion into 1) a further recess of the second imbalance shaft half and 2) a further recess in at least one of the coupling device and the sleeve device, wherein at least one of the further recesses has a groove which runs helically at least in sections thereof, and wherein the further control slide is configured to be displaced by way of a further piston/cylinder unit.

8. The vibration exciter as claimed in claim 7, wherein the second imbalance shaft half has a further cavity, and the further control slide and the further actuation device are arranged within the further cavity.

9. The vibration exciter as claimed in claim 5, wherein an orbit of the imbalance mass on the first imbalance shaft half about the first imbalance shaft half at least partially surrounds at least one of the cavity, the actuation device, a piston of the piston/cylinder unit, and a cylinder of the piston/cylinder unit.

10. The vibration exciter as claimed in claim 1, wherein a bearing device surrounds the first imbalance shaft half and is arranged axially between the imbalance mass on the first imbalance shaft half and the coupling device, and at a side of the imbalance mass arranged on the first imbalance shaft half which, faces away from the coupling device, there is arranged a further bearing device which surrounds the first imbalance shaft half.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) These and further features of the invention will be discussed in more detail below on the basis of an example and with reference to the appended FIGURE, in which:

(2) FIG. 1 shows a section of a vibration exciter according to the invention in a plan view.

DETAILED DESCRIPTION

(3) The FIGURE schematically shows an embodiment of a vibration exciter 1 in a view from above in a section in a plane running substantially parallel to the surface of the ground to be processed. The vibration exciter 1 may be used in particular in a vibratory plate foreground compaction.

(4) The vibration exciter 1 has a first imbalance shaft 3 which is driven in rotation by a drive device 2 and which has imbalance masses 4a and 4b arranged or fastened thereon. By means of two gearwheels 5 and 6, the rotational movement of the first imbalance shaft 3 is transmitted in positively locking fashion to a second imbalance shaft 7 such that the latter rotates in the opposite direction.

(5) The second imbalance shaft 7 has a first imbalance shaft half 8a and a second imbalance shaft half 8b which is arranged coaxially with respect to the first imbalance shaft half 8a and which is rotatable relative to the first imbalance shaft half. The two imbalance shaft halves 8a and 8b are inserted into both sides of an adjustment sleeve 9 which belongs to a coupling device and which couples the two imbalance shaft halves 8a and 8b in positively locking fashion but such that they are rotatable relative to one another. The gearwheel 6 is arranged in encircling fashion on the adjustment sleeve 9. The adjustment sleeve 9 consequently forms, with the gearwheel 6, a coupling device for the positively locking coupling of the first imbalance shaft 3 to the second imbalance shaft 7, which is composed of the two imbalance shaft halves 8a, 8b.

(6) Adjustable imbalances 10a and 10b are arranged or fastened on the two imbalance shaft halves 8a and 8b. To realize an individual relative rotation of the adjustable imbalances 10a, 10b about the axis of rotation of the second imbalance shaft 7, respective relative-rotation devices 11a, 11b are provided and are recessed into the imbalance shaft halves 8a and 8b, which are in the form of hollow shafts.

(7) By means of the relative-rotation devices 11a, 11b, the phase angle of the adjustable imbalances 10a, 10b relative to the imbalance masses 4a, 4b arranged on the first imbalance shaft 3 can be adjusted. By means of the centrifugal force vectors that act on the imbalance masses 4a, 4b, 10a, 10b during a rotation of the imbalance masses 4a, 4b and 10a, 10b in each case about the oppositely rotating imbalance shafts 3, 7, it is possible, with a shifted phase angle, to realize a forward or reverse movement of the ground compaction device that is operated by way of the vibration exciter 1. By means of a relative rotation of the adjustable imbalances 10a, 10b with respect to one another, a yaw moment and thus a rotation of the ground compaction device is generated about a vertical axis of the vibration exciter 1 or of the ground compaction device, said vertical axis projecting vertically out of the plane of the drawing.

(8) Below, only the relative-rotation device 11a will be discussed. The relative-rotation device 11b is of identical construction and, in the FIGURE, is illustrated mirror-symmetrically with respect to the relative-rotation device 11a.

(9) The relative-rotation device 11a has, as actuation device, a piston 12a arranged in a cover sleeve, the latter being arranged or fastened on a housing 19 of the vibration exciter 1 and engaging into the imbalance shaft half 8a. Part of the cover sleeve is formed by a cylinder 22a in which the piston 12a is mounted in axially movable fashion. The cover sleeve, the cylinder 22a and the piston 12a are rotationally decoupled from the imbalance shaft half 8a by way of bearing 18a and are fastened to the housing 19 of the vibration exciter 1.

(10) The piston 12a can axially displace a slide 13a within the imbalance shaft half 8a. The slide 13a bears a transverse pin 14a which extends through a helical groove 15a provided in a wall of the first imbalance shaft half 8a, which is in the form of a hollow shaft. At the same time, the transverse pin 14a engages into a longitudinal groove 16 which is formed on the inner side of the adjustment sleeve 9 and which lies radially outside or above the helical groove 15a. Owing to the helical profile of the groove 15a, the axial displacement of the slide 13a with the transverse pin 14a has the effect of forcibly imparting to the first imbalance shaft half 8a a rotational movement relative to the adjustment sleeve 9. In this way, the relative rotational position of the adjustable imbalance 10a relative to the adjustment sleeve 9, relative to the adjustable imbalance 10b and relative to the first imbalance shaft 3 is varied.

(11) The helical groove 15a forms a recess of the first imbalance shaft half 8a and is preferably arranged in a region of the first imbalance shaft half 8a which faces toward the central axis of symmetry of the housing 19 (exciter housing) and/or of the ground compaction device. The recess is preferably arranged in a half of the first imbalance shaft half 8a, and/or the recess extends over at most a half of the length of the first imbalance shaft half 8a, which half faces toward the central axis of symmetry. The recess is particularly preferably arranged in a third of the first imbalance shaft half 8a, and/or the recess extends over at most a third of the length of the first imbalance shaft half 8a, which third faces toward the central axis of symmetry.

(12) During working operation, the adjustable imbalances 10a and 10b seek, owing to their inertia, to change their respective phase angle in a retarding direction, and thus push the pistons 12a and 12b back into their initial positions. To further assist the return movement of the pistons 12a, 12b, spring devices may be provided, and arranged for example within the cylinders 22a, 22b. The spring devices can support the pistons 12a, 12b for example against a face side, facing toward the adjustment sleeve 9, of the respective cylinder 22a, 22b.

(13) In this arrangement, the relative-rotation device 11a is almost entirely recessed into a cavity of the first imbalance shaft half 8a. Only an inlet 17a for hydraulic fluid for the movement or exertion of pressure on the piston 12a projects out of the first imbalance shaft half 8a. The piston 12a, at least in a maximally retracted position, is entirely received in the second imbalance shaft 7 and/or recessed into the first imbalance shaft half 8a. The piston 12a, the cylinder 22a and the inlet 17a are in this case decoupled from a rotational movement of the first imbalance shaft half 8a and of the slide 13a by way of a bearing 18a, which serves as a rotational decoupling means.

(14) Furthermore, it may be the case that the end region of the piston 12a, even in a maximally deployed position, that is to say remote from the central axis of symmetry of the housing 19, is received entirely in the second imbalance shaft 7 and/or does not project out of the contour formed by the housing 19 (exciter housing). The exciter housing is to be understood to mean the housing 19 without further fixtures, which housing serves for receiving the shafts 3, 7 and imbalance masses 4a, 4b, 10a, 10b.

(15) In this arrangement, an orbit of the adjustable imbalance 10a about the first imbalance shaft half 8a may at least partially or even entirely surround the cavity, the piston 12a and/or the cylinder 22a. This makes it possible for the adjustable imbalance 10a to be arranged far to the outside on the first imbalance shaft half 8a, that is to say with a large spacing to an axis of symmetry, running through the gearwheels 5, 6, of the vibration exciter 1, and for example directly adjacent to a housing 19 of the vibration exciter 1. Consequently, during the rotation of the adjustable imbalance 10a, a large lever arm acts, which can yield a high rate of rotation of the ground compaction device about the vertical axis.

(16) Good controllability of the ground compaction device can be attained in particular if, as shown in the FIGURE, the second and third imbalance masses 10a, 10b (adjustable imbalances 10a, 10b) are arranged far remote from the center of the exciter. In this way, it can be achieved that the imbalance masses 4a, 4b and the second and third imbalance masses 10a, 10b (adjustable imbalances 10a, 10b) are arranged axially offset with respect to one another such that there is only a small overlap, or no overlap, between the imbalance masses 4a, 4b, 10a, 10b. The overlap between an imbalance mass 4a, 4b of the first imbalance shaft 3 and an imbalance mass 10a, 10b (adjustable imbalance 10a, 10b) of the second imbalance shaft 7 is preferably at most 50 percent. To calculate this, the axial length of the overlap is set in a ratio with respect to the added-together total length of the two imbalance masses. The overlap is more preferably at most 25 percent. There is particularly preferably no overlap between the imbalance masses 4a, 4b, 10a, 10b.

(17) An inner bearing 20a is arranged axially between the adjustable imbalance 10a and the adjustment sleeve 9, and a further inner bearing 20b is arranged between the adjustable imbalance 10b and the adjustment sleeve 9. The adjustment sleeve 9 with the gearwheel 6 is thus mounted between the adjacently arranged inner bearings 20a and 20b. Furthermore, the second imbalance shaft 7 is mounted on the housing 19 by way of outer bearings 21a, 21b. The outer bearings 21a, 21b may be arranged adjacent to or in the direct vicinity of the adjustable imbalances 10a, 10b. The adjustment sleeve 9 is positioned on, and supported by, the end regions of the first imbalance shaft half 8a and of the second imbalance shaft half 8b.

(18) Thus, the first imbalance shaft half 8a is mounted in the housing 19 by way of the bearings 20a and 21a, whereas the second imbalance shaft half 8b is mounted in the housing 19 by way of the bearings 20b and 21b.

(19) Elastic deformations of the second imbalance shaft 7, which are imparted to the latter by the rotating adjustable imbalances 10a and 10b, are lessened by the bearings 20a, 20b and 21a, 21b. The adjustment sleeve 9 with the gearwheel 6 arranged thereon is thus subjected to elastic displacement only to a small extent. Consequently, the gearwheel pairing 5, 6 runs relatively quietly, and is subjected to significantly lower mechanical load. Furthermore, the bearings 20a, 20b, 21 a, 21b are arranged, with regard to the first and second imbalance shaft halves 8a, 8b, such that the loads imparted by the second and third imbalance masses 10a, 10b (adjustable imbalances 10a, 10b) are dissipated by the respectively adjacently arranged bearings, such that the region of the respective imbalance shaft half 8a, 8b in which the recess (helical groove 15a, 15b) is arranged is isolated from the load.

(20) Owing to the splitting of the second imbalance shaft 7 into the two imbalance shaft halves 8a and 8b, it is possible in the embodiment shown in the FIGURE for the adjustable imbalances 10a and 10b to be arranged directly on the imbalance shaft halves 8a and 8b. The adjustment sleeve 9 is thus not subjected to load by the imbalances, but is spatially separate from the second and third imbalance masses 10a, 10b (adjustable imbalances 10a, 10b). Furthermore, in each case one bearing point is arranged between the adjustment sleeve 9 and the second and third imbalance masses 10a, 10b (adjustable imbalances 10a, 10b), such that the action of the imbalance masses (adjustable imbalances 10a, 10b) on the sleeve (adjustment sleeve 9), and on the adjustment arrangement 9, 13a, 13b, 14a, 14b, 15a, 15b as a whole, is minimized. This increases the robustness of the vibration exciter 1. In the exemplary embodiment shown, the torque flow runs from the drive device 2 via the first imbalance shaft 3, the gearwheel pairing 5, 6, the adjustment sleeve 9, the engagement elements (transverse pins) 14a, 14b, in each case to the first and second imbalance shaft halves 8a, 8b and in each case onward to the second and third imbalance masses 10a, 10b (adjustable imbalances 10a, 10b).

(21) The relative rotatability of the adjustable imbalances 10a and 10b is in this case ensured by way of the centrally arranged adjustment sleeve 9. The adjustment sleeve 9 is in this case isolated from the weight of the adjustable imbalances 10a and 10b and is furthermore protected, by the inner bearings 20a and 20b, from the shaft bending caused by the rotating adjustable imbalances 10a, 10b. Consequently, quieter operation and an increased service life of the vibration exciter 1 can be expected.

(22) Owing to the arrangement of the relative-rotation devices 11a, 11b within the imbalance shaft halves 8a, 8b formed as hollow shafts, the adjustable imbalances 10a and 10b can be arranged far to the outside on the second imbalance shaft 7 and thus with a large lever arm with respect to the vertical axis of the ground compaction device. This permits a high level of rotational dynamics and improved traveling behavior of the ground compaction device or vibratory plate in accordance with an operator demand. Traveling maneuvers can be realized more quickly, leading to greater productivity of the ground compaction device. This also applies in particular to remote-controlled vibratory plates of compact design.