Vibration generator

Abstract

Vibration generator, in particular for a vibratory rammer, comprising at least two shafts (21, 21', 22, 31, 32) arranged parallel to each other, and at least two unbalanced masses (25, 25', 26, 35, 36) mounted on one or more of the shafts (21, 21', 22, 31, 32), wherein a phase shifter is arranged for adjusting the relative rotational position of the unbalanced masses (25, 25', 26, 35, 36) relative to each other, which comprises a rotor shaft (41) having at least one gear, on which a housing (42) having at least one gear (43) is arranged, which is hydraulically rotatable relative to the shaft (41), wherein means for blocking the rotatability of the housing (42) relative to the rotor shaft (41) are arranged, wherein the means comprise a locking element (6) which is either attached to is arranged in the housing (42) or in direct or indirect gear mesh with a gear (43) of the housing (42) and when the shafts (21, 21', 22,31, 32) engages positively in a recess of the shaft (41, 21') on which the housing (42) or the gear (23) connected to it via a gear mesh is arranged, and which, when the shafts (21, 21', 22, 31, 32) rotate, automatically moves out of the recess (411, 211) after a certain rotational speed has been exceeded.

Description

[0001] The invention relates to a vibration generator, in particular for a vibratory hammer, according to the preamble of claim 1.

[0002] In construction, vibration generators such as vibrators, shakers, or vibratory hammers are used to drive or pull profiles into the ground or to compact soil material. The soil is excited by vibration, reaching a "pseudo-fluid" state. Static load then presses the driven material into the subsoil. The vibration is characterized by linear motion and is generated by pairs of counter-rotating eccentric weights within a vibrator drive. The eccentric weights are mounted on eccentric shafts, which are rotated by drive motors. Vibration generators are characterized by the installed eccentricity (referred to in technical circles as "static moment"), the vibrating mass, the permissible centrifugal force, and the maximum rotational speed. The effective eccentricity depends on the phase relationship between the installed eccentric weights.

[0003] To achieve optimal driving force and good compaction depending on the material being driven and the soil properties, it is desirable to control the amplitude, frequency, or direction of force of the vibrator. The vibration is most effectively adjusted by changing the static moment through a phase shifter, which alters the phase of the unbalanced weights. When the vibrator is started, the soil's natural frequency range is traversed. If the soil is excited in its resonant range, the amplitude of the ground vibration becomes very large, which can lead to damage to adjacent structures. Therefore, it is essential that no unbalanced weights are active when the vibrator is started. For this reason, before switching off the vibrator, the phase of the installed unbalanced weights is adjusted using a phase shifter so that the centrifugal force components cancel each other out in all directions.This reduces the effective static moment and amplitude to zero. The vibrator then runs off without vibration and, under normal circumstances, starts up again without vibration the next time it is switched on.

[0004] When the vibrator is switched off, i.e., when the unbalance shafts are not being driven by the drive motors, the phase relationship of the unbalance shafts relative to each other can unintentionally change during extended periods of inactivity or transport. Since, depending on the design, sufficient energy supply to the phase shifter (e.g., a rotary vane motor) may only be available several seconds after the drive motors are activated, the phase shifter cannot change the phase relationship in a controlled manner while stationary. Therefore, starting the vibrator with static torque cannot be ruled out. Furthermore, if a rotary vane motor is used as the phase shifter, it must be considered that these motors inherently exhibit internal leakage, which can also be the cause of the unintentional phase change of the vibration generator described above.

[0005] German patent DE 20 2007 005 283 U1 discloses a vibration generator with shafts equipped with unbalanced masses, wherein a rotary vane motor is arranged for adjusting the relative rotational position of the unbalanced masses to one another. A spring-applied multi-disc brake, which is hydraulically actuated, is arranged to lock the stator housing of the rotary vane motor with its rotor shaft after reaching a desired static torque. A disadvantage of this solution is that, depending on the design of the spring-applied multi-disc brake, a hydraulic energy supply is required either for releasing or closing it. Furthermore, the implementation of the multi-disc brake proves to be complex and requires additional installation space.

[0006] The invention aims to remedy this problem. The invention is based on the objective of creating a vibration exciter in which unintentional shifts in the phase of the unbalanced weights are prevented when the device is switched off, without requiring additional elements for supplying electrical or hydraulic energy, and which also features a compact design. According to the invention, this objective is achieved by the features of the characterizing part of claim 1.

[0007] The invention provides a vibration exciter in which unintentional adjustment of the phase position of the imbalances is prevented when the unit is switched off, and which also features a compact design. The means for blocking the rotation of the phase shifter housing relative to its rotor shaft comprise a locking element that is arranged either on the housing, on a component non-rotatably connected to the housing, or on a gear in direct or indirect gear mesh with a gear of the housing. When the shafts are stationary, this locking element engages positively in a recess of the shaft on which the housing or the gear connected to it via gear mesh is arranged. Upon rotation of the shafts exceeding a certain speed, the locking element automatically moves out of the recess, thus locking the phase shifter when the shafts are stationary.The locking mechanism can be either direct or indirect. In direct locking, the locking element is located on the housing of the phase shifter or on a component (such as a gear) that is rotationally fixed to it. In its rest position, the locking element engages in a recess in the stationary shaft, thus positively connecting the housing to the shaft. The phase shifter is therefore locked. When the shaft rotates, the locking element is moved out of the recess in the shaft when a certain rotational speed, which is significantly lower than the operating speed, is exceeded, thereby releasing the phase shifter. Advantageously, the recess in the shaft is positioned such that the locking element engages when the phase shifter is in a position where the relative unbalanced masses are in a rotational orientation relative to each other, and the static moment is zero (phase shifter in its neutral position).

[0008] In the indirect locking mechanism, the locking element is mounted on a gear rotatably arranged on an adjacent shaft. This gear meshes with the gear of the phase shifter housing and, in its rest position, engages in a recess of this stationary shaft, thus positively locking the gear to the shaft. This blocks the rotation of the gear. The gear meshing with the phase shifter housing also simultaneously blocks the rotation of the housing. The locking mechanism does not necessarily have to be mounted directly on the shaft next to the phase shifter; rather, it can be mounted on any unbalanced shaft and connected to the housing gear via multiple gear meshes, i.e., via several meshing gears.

[0009] In a further development of the invention, the locking element is radially displaceable within a guide of a flange part attached to the housing or to the gear connected via a gear mesh, and is preloaded against the shaft by a spring element. This results in a radial displacement of the locking element from the shaft recess caused by centrifugal force, depending on the rotational speed of the housing or the gear to which the flange part is attached. The spring element ensures the positioning of the locking element as long as the magnitude of the centrifugal force does not exceed the magnitude of the spring preload. The spring constant of the spring element thus defines the limiting rotational speed at which movement of the locking element from the shaft recess occurs. Preferably, the spring element is formed by a helical spring or a wave spring.

[0010] In one embodiment of the invention, the guide is formed by a bore which is closed by a cover plate detachably connected to the flange part. This allows for easy assembly of the locking element. In this context, the term "bore" is to be understood as a through-hole in the sense of a through-pass. Depending on the design of the locking element guided within it, the bore can, for example, be an elongated hole or have a rectangular cross-section.

[0011] In a further embodiment of the invention, the locking element is cylindrical and preferably has a shoulder for the engagement of a spring element. This achieves uniform guidance within a bore, similar to a piston.

[0012] In a further embodiment of the invention, the flange part is designed in an annular or partially annular form, encompassing the shaft at least partially. This achieves a radial positioning of the locking element arranged in the guide.

[0013] In a further development of the invention, the flange part is designed as an unbalanced element. This results in a more compact design of the vibration generator.

[0014] In one embodiment of the invention, the locking element has a threaded bore on its side facing away from the shaft for receiving a screw. This allows the locking element to be manually removed from the recess in the shaft by means of a screw inserted into the threaded bore.

[0015] In a further embodiment of the invention, the phase shifter is a rotary vane swivel motor. The use of a rotary vane swivel motor enables a relative adjustment of the unbalanced masses to each other without requiring the conversion of a linear motion into a rotary motion, thus achieving a compact design.

[0016] Other embodiments and configurations of the invention are specified in the remaining dependent claims. Exemplary embodiments of the invention are illustrated in the drawings and are described in detail below. The drawings show: Figure 1: Schematic representation of a vibration generator a) with locking element engaged; b) with locking element disengaged (phase shifter in zero position); c) with locking element disengaged (phase shifter out of zero position); Figure 2: Schematic spatial representation of the excitation drive of the vibration generator. Figure 1Figure 3: illustration of the swivel motor of the excitation gearbox Figure 2 with rotor shaft; Figure 4: the spatial representation of the rotary motor arrangement from Figure 3 in section AA a) with locking element engaged; b) with locking element disengaged; Figure 5: the representation of the rotary motor arrangement from Figure 3 with locking element engaged a) in longitudinal section; b) in section AA; Figure 6: the representation of the swivel motor arrangement from Figure 3 a) in longitudinal section; b) in section AA; Figure 7: the representation of the swivel motor arrangement from Figure 3 with locking element disengaged (position of the phase shifter other than zero position) a) in longitudinal section; b) in section AA; Figure 8: the schematic representation of the excitation drive of a vibration generator in a further embodiment; Figure 9: the representation of the unbalanced shaft with locking element arrangement of the excitation drive. Figure 8with locking element engaged a) in longitudinal section; b) in section BB; Figure 10: the representation of the unbalanced shaft with locking element arrangement of the exciter gear from Figure 8 with locking element disengaged (position of the phase shifter in zero position) a) in longitudinal section; b) in section BB; Figure 11: the representation of the unbalanced shaft with locking element arrangement of the excitation gear from Figure 8 with locking element disengaged (position of the phase shifter other than zero position) a) in longitudinal section; b) in section BB;

[0017] The vibration generator chosen as an exemplary embodiment is designed as a vibratory transmission (see...). Figure 1It essentially consists of a housing 1 in which two shaft groups 2, 3 are arranged, each consisting of two shafts 21, 22 and 31, 32 respectively, equipped with gears 23, 24 and 33, 34 respectively, which are rotatably mounted in the housing 1, and a rotary motor 4, whose stator housing 42 is equipped with a first gear 43 and whose rotor shaft 41 is equipped with a second gear 44.

[0018] The first shaft 21 and the second shaft 22 of the first shaft group 2 are identical and rotatably mounted in bearings 11 of the housing 1. A first gear 23 is rotatably mounted on each of the shafts 21 and 22, and a second gear 24 is adjacent to it and non-rotatably connected to the shaft 21 and 22. The first gear 23 is provided with internal eccentric weights 25 on both sides. The second gear 24 is provided with an external eccentric weight 26 on its outwardly facing side. A second external eccentric weight is mounted on each of the shafts 21 and 22 at a distance from the first gear 23.

[0019] The shafts 31, 32 of the second shaft group 3 are identical in construction to the shafts 21, 22 of the first shaft group 2 and are also rotatably mounted in bearings 11 of the housing 1. A first gear 33 is rotatably mounted on each shaft 31, 32, and a second gear 34 is adjacent to it and non-rotatably connected to the shaft 31, 32. The first gear 33 is provided with internal unbalanced masses 35 on both sides. The second gear 34 is provided with an external unbalanced mass 36 on its outwardly facing side. A second external unbalanced mass is mounted on each shaft 31, 32 at a distance from the first gear 33.

[0020] The second shafts 22, 32 of the two shaft groups 2, 3 are each connected to a hydraulic motor 7, by which they can be driven. The first gears 23, 33 of the second shafts 22, 32 are meshed with the first gears 23, 33 of the first shafts 21, 31, and the second gears 24, 34 of the second shafts 22, 32 are meshed with the second gears 24, 34 of the first shafts 21, 31.

[0021] Between the first shafts 21, 31 of the two shaft groups 2, 3, a shaft is rotatably mounted in the housing 1. This shaft is, in effect, the rotor shaft 41 of a rotary actuator 4 arranged centrally on it. The rotary actuator 4 is formed in a known manner, as described, for example, in DE 20 2007 005 283 U1, from a rotor shaft 41 provided with a rotor blade, which is arranged in a stator housing 42 located on the rotor shaft 41. A space is formed between the rotor shaft 41 and the stator housing 42, which is divided by the rotor blade arranged on the rotor shaft 41 (not shown) and by a stator blade integrally formed on the stator housing 42 (not shown), so that two working chambers are formed which are connected by hydraulic lines.

[0022] A first gear 43 is fixedly mounted on the stator housing 42 of the rotary motor 4. The first gear 43 is positioned on the stator housing 42 such that it meshes with the first gears 23, 33 of the first shafts 21, 31. A second gear 44 is fixedly mounted on the rotor shaft 41 at a distance from the rotary motor 4 and positioned such that it meshes with the second gears 24, 34 of the first shafts 21, 31.

[0023] In the exemplary embodiment according to Figure 1An annular flange 5 is arranged on the rotor shaft 41 and attached to the stator housing 42. The flange 5 has an inner diameter that is slightly larger than that of the rotor shaft 42, which rotates within the flange. The flange 5 is provided with a radial bore 51 that terminates perpendicular to the end face of a recess 52 formed in the outer edge of the flange 5. On either side of the bore 51, parallel to and spaced apart from it, two threaded blind holes 53 are formed in the area of ​​the recess 52. A cover plate 54 is inserted into the recess 52 and is secured by screws that are screwed into the threaded blind holes 53. A blind hole 55 is formed in the cover plate 54, which is aligned with the bore 51 of the flange 5.The blind hole bore 55 has an inner diameter that essentially corresponds to the outer diameter of the shaft 62 of the locking element 6, which is guided in it.

[0024] A locking element 6 is slidably mounted in bore 51. The locking element 6 is essentially cylindrical and has a head 61 to which a reduced-diameter shaft 62 is attached. An axially threaded blind hole 63 is centrally machined into the shaft 62. The outer diameter of the head 61 corresponds essentially to the inner diameter of bore 51 in the flange part 5 in which it is guided. A spring 64, designed as a helical spring in this embodiment, is mounted on the shaft 62 against the cover plate 54 and biases the locking element 6 against the rotor shaft 41. A recess 411 is provided in the rotor shaft 41, into which the head 61 of the locking piece 6 engages in the rotational position of the rotor shaft 41, in which the unbalance masses 25, 26, 35, 36 are positioned relative to each other such that the static moment of the vibrator drive is zero.

[0025] Naturally, the flange part 5 can also have several bores 51 of the type described above, each closed by a cover plate 54, in which a locking element 6 of the type described above is biased against the rotor shaft 41 by a spring 64, wherein correspondingly positioned recesses 411 are provided in the rotor shaft to receive the head 61 of each associated locking element 6 in the position of the rotor shaft 41 described above, in which the static moment of the vibrator drive is zero. Advantageously, these are arranged at equal intervals from each other.

[0026] In the rest position of the vibration generator, the rotor shaft 41 is in a rotational position in which the unbalanced masses 25, 26, 35, 36 are positioned relative to each other such that the static moment of the vibrator drive is zero. In this rest position, the locking element 6, which is pre-tensioned against the rotor shaft 41 by the spring 64, engages with its head 61 in the recess 411 of the rotor shaft 41 (see figure). Figure 4a The stator housing 42, with its attached flange part 5, is thus locked against rotation on the rotor shaft 41 by means of the locking element 6. This prevents unintentional adjustment of the unbalance masses 25, 26, 35, 36 relative to each other.

[0027] When the vibration generator is put into operation, the shafts 21, 22, 31, 32, as well as the rotor shaft 41, are set into rotation by the hydraulic motors 7. Due to the rotation of the rotor shaft 41 with the stator housing 42 mounted on it and the flange part 5 attached to it, a centrifugal force acts on the locking element 6, acting against the spring force of the spring 64. When the rotor shaft 41 reaches a speed at which the centrifugal force acting on the locking element 6 is greater than the spring force of the spring 64, the locking element 6 is moved radially outwards until its shaft 62 abuts the end face of the cover plate 54 (see figure). Figure 4b This releases the blockage between flange part 5 and rotor shaft 41. Adjustment of the static moment by adjusting the unbalanced masses 25, 26, 35, 36 relative to each other is now possible.

[0028] To deactivate the vibration generator, the static torque is reduced to zero via the rotary actuator 4. The hydraulic motors 7 are then switched off, causing the rotational speed of the rotor shaft 41 and consequently the magnitude of the centrifugal force acting on the locking element 6 to decrease. When the rotational speed of the rotor shaft 41 reaches the point where the centrifugal force acting on the locking element 6 is less than the spring force of the spring 64, the locking element 6 is moved radially inwards until its head rests in the recess 411 of the rotor shaft 41. The vibration generator is now again secured against unintentional adjustment of the static torque.

[0029] Two essential criteria must be considered when designing such a self-locking mechanism: Firstly, the spring force must be selected such that the locking element cannot unintentionally disengage during vibrations during transport of the vibration generator. Secondly, the centrifugal force at operating speed must be significantly greater than the spring force so that the contact force between the locking element 6 and the cover plate 54 is significantly greater than the maximum inertial force resulting from the vibration (i.e., centrifugal force - spring force > mass of locking element * acceleration). This prevents any relative movement between the locking element 6, flange part 5, and cover plate 54 during operation. This leads to a significant reduction in the number of load cycles of the spring 64 (thereby reducing the risk of fatigue or fatigue fracture) and to less wear between the locking element 6, flange part 5, and cover plate 54.For a vibrator with an operating speed of 1600 rpm or higher, this state is reached, for example, at 1200 rpm. In the same example, the locking element 6 would already move completely out of the recess 411 at 700 rpm.

[0030] In the exemplary embodiment according to Figure 8 At the location of the flange part described in the preceding embodiment, which is attached to the stator housing and in which the locking element 6 is guided radially displaceably, an inner unbalance mass 25' of the two unbalance masses connected to the first rotatably mounted gear 23 of the first shaft 21 of the first shaft group 2 is provided with a guide corresponding to the guide of the flange part present in the first embodiment.

[0031] Accordingly, the inner unbalance mass 25' is provided with a radial bore 251 that terminates perpendicularly to the end face of a recess 252 formed in the outer edge of the inner unbalance mass 25'. On both sides of the bore 251, parallel to and spaced apart from it, two threaded blind holes 253 are formed in the area of ​​the recess 252. A cover plate 254 is inserted into the recess 252 and is fastened by screws that are screwed into the threaded blind holes 253. A blind hole 255 is formed in the cover plate 254, which is aligned with the bore 251 of the inner unbalance mass 25'. The blind hole 255 has an inner diameter that corresponds essentially to the outer diameter of the shaft 62 of the locking element 6, which is guided in it.

[0032] The locking element 6, which is designed according to the first embodiment, is in this embodiment slidably mounted in the bore 251 of the inner unbalanced mass 25' and preloaded against the first shaft 21' by the spring 64. A recess 211 is provided in the first shaft 21', into which the head 61 of the locking element 6 engages in the rotational position of the shaft 21' in which the unbalanced masses 25', 26, 35, 36 of the shafts 21', 22, 31, 32 are positioned relative to each other such that the static moment of the vibrator drive is zero.

[0033] In the rest position of the vibration generator, the first shaft 21' is in a rotational position in which the unbalanced masses 25', 26, 35, 36 are positioned relative to each other such that the static moment of the vibrator drive is zero. In this rest position, the locking element 6, which is pre-tensioned against the first shaft 21' by the spring 64, engages with its head 61 in the recess 211 of the first shaft 21' (see figure). Figure 9 The first gear 23, connected to the internal unbalanced mass 25', is thereby locked against rotation on the first shaft 21'. The gear mesh of the first gear 23 of the first shaft 21' with the first gear 43 of the stator housing 42 effectively prevents rotation of the stator housing 42 relative to the rotor shaft 41. The vibration generator is thus secured against unintentional changes in the static torque.

[0034] When the vibration generator is started up, the shafts 22, 32 are set into rotation by the motors 7. The rotation of the first shaft 21' with the internal unbalanced mass 25' attached to it exerts a centrifugal force on the locking element 6, acting against the spring force of the spring 64. When the first shaft 21' reaches a rotational speed at which the centrifugal force acting on the locking element 6 is greater than the spring force of the spring 64, the locking element 6 is moved radially outwards until its shaft 62 abuts the cover plate 254 (see figure). Figure 10 This releases the blockage between the inner unbalanced mass 25' and the first shaft 21'. Adjustment of the static moment by adjusting the unbalanced masses 25, 26, 35, 36 relative to each other by the swivel motor 4 is now possible (see figure). Figure 11 The deactivation of the vibration generator is identical to the first embodiment described above.

[0035] The coupling via one or more locking elements 6 results from the interaction of spring and centrifugal forces, creating a closed system with purely mechanical operation that requires no control variables other than the existing rotational speed of the gearbox. The system is therefore independent of hydraulics and control technology and can thus be easily retrofitted to existing vibration generators.

[0036] The threaded blind hole 63 in the shaft 62 of the locking element 6 allows the positive locking connection created by the locking element 6 to be manually released, for example, to pivot the rotary drive for maintenance, assembly, or disassembly. For this purpose, a screw is inserted, for example, through the through-hole 56, 256 into the threaded blind hole 63 of the locking element 6. The locking element 6 can then be pulled out of the recess 411 of the rotor shaft (exemplary embodiment 1) or the recess 211 of the first shaft 21' (second exemplary embodiment) using the screw.

Claims

1. Vibration generator, in particular for a vibratory rammer, comprising at least two shafts (21, 21', 22, 31, 32) arranged parallel to each other, and at least two unbalanced masses (25, 25', 26, 35, 36) mounted on one or more of the shafts (21, 21', 22, 31, 32), wherein a phase shifter is arranged for adjusting the relative rotational position of the unbalanced masses (25, 25', 26, 35, 36) relative to each other, which comprises a rotor shaft (41) having at least one gear, on which a housing (42) having at least one gear (44) is arranged, which is rotatable relative to the shaft (41), wherein means for blocking the rotatability of the housing (42) relative to the rotor shaft (41) are arranged. characterized by the fact thatThe means comprise a locking element (6) which is arranged either on the housing (42), on a component non-rotatably connected to the housing, or on a gear (23) in direct or indirect gear mesh with a gear (43) of the housing (42), and which, when the shafts (21, 21', 22, 31, 32) are at rest, engages positively in a recess of the shaft (41, 21') on which the housing (42) or the gear (23) connected to it via a gear mesh is arranged, and which, when the shafts (21, 21', 22, 31, 32) rotate, automatically moves out of the recess (411, 211) after a certain rotational speed has been exceeded.

2. Vibration generator according to claim 1, characterized by the fact that the housing (42) which has at least one gear (44) is rotatable hydraulically or electrically relative to the shaft (41).

3. Vibration generator according to claim 1 or 2, characterized by the fact thatthe locking element (6) is mounted radially displaceable in a guide and is preloaded against the shaft (41, 21') by means of a spring element.

4. Vibration generator according to claim 3, characterized by the fact that the locking element (6) is radially displaceable in a guide of a flange part (5) attached to the housing (42) or the gear (23) connected via a gear engagement and is preloaded against the shaft (41, 21') by a spring element.

5. Vibration exciter according to claim 3 or 4, characterized by the fact that the spring element is formed by a coil spring (64) or a wave spring.

6. Vibration exciter according to one of claims 3 to 5, characterized by the fact that the guide is formed by a bore (51, 251) which is closed by a cover plate (54, 254) which is detachably connected to the flange part (5, 25').

7. Vibration exciter according to one of the aforementioned claims, characterized by the fact that the locking element (6) is cylindrical in shape.

8. Vibration generator according to one of claims 3 to 7, characterized by the fact that the flange part (5) is ring-shaped or partially ring-shaped and encompasses the shaft (41, 21') at least in part.

9. Vibration generator according to claim 8, characterized by the fact that the flange part is designed as an imbalance (25').

10. Vibration generator according to one of the aforementioned claims, characterized by the fact that the locking element (6) has a threaded bore (63) on its side facing away from the shaft (41, 21') for receiving a screw.

11. Vibration exciter according to one of the aforementioned claims, characterized by the fact that the phase shifter is a rotary vane rotary motor (4).

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