This application claims priority to foreign patent application DE 10 2008 050 576.5, filed on Oct. 6, 2008, the disclosure of which is incorporated herein by reference in its entirety.
The present invention relates to a device for generating a circular oscillation or a directional oscillation.
Devices for generating circular or directional oscillation are used in particular in construction machines for soil compaction. Typically, two main shafts situated in parallel in the same housing are used, on each of which unbalance weights are located. To generate a directional oscillation, the main shafts are set into rotation synchronously and in opposite directions using directly meshing spur gears, for example. For the continuous adjustment of the oscillation amplitude of the exciter force, the angles of the unbalance weights are changed so that the effective exciter force, which is composed of the centrifugal forces of individual unbalance weights, increases or decreases continuously within a predetermined range.
Shafts are typically used for adjusting the oscillation amplitude and/or exciter force, on which unbalance weights are located, which are connected rotationally fixed to the shaft, on the one hand, and are mounted so they are rotatable thereon, on the other hand. To adjust the angle, the rotatably-mounted unbalance weights are adjusted and locked in their positions relative to the rotationally-fixed unbalance weights, typically only at a standstill.
An oscillation exciter having two unbalance bodies displaceable to one another is known from DE 2736264 A1, which also allows an adjustment during the operation. For this purpose, a first unbalance body in a forked part rotatable around a transverse axis is connected using a pushrod to a slide displaceable axially on the rotational axis to shift the unbalance body. A further unbalance body is positively connected to the first unbalance body using a gearing. If the slide is moved axially, the two unbalance bodies pivot either toward or away from one another. The amplitude of the exciter force is varied in this way. However, it is disadvantageous that for this purpose the axially displaceable slide and the pushrod connection occupy a large amount of space on the rotational axis, so that a compact construction of the oscillation exciter is impossible.
Furthermore, the disadvantage is that in the oscillation exciter according to DE 2736264 A1, no latitude is given in regard to the configuration of unbalance bodies, because only two unbalance bodies may always be situated per rotation shaft. For example, if one wants to situate two further unbalance bodies on the same rotational axis, a further slide having a further pushrod must be situated on the other front face of the shaft, whereby the installation space would be enlarged still further. Furthermore, the pushrod represents a sensitive part as the connection part to the adjustment element. In addition, because of the asymmetrical configuration of the pushrod and because of the shape of the unbalance bodies themselves, even with the unbalance bodies completely shifted, no “zero setting” of the exciter force is possible, so that the machine continuously generates an imbalance and thus a directional oscillation as long as the shaft rotates.
Embodiments of the present invention advantageously overcome the disadvantages of the known prior art. In particular, embodiments of the present invention allow a very compact construction for a device for generating a circular oscillation or a directional oscillation, the oscillation amplitude of the exciter force being continuously adjustable reliably and comfortably between a minimal value, which can be zero, but does not have to be, and a maximum value. In addition, embodiments of the present invention offer a modular expansion of the main shaft with additional unbalance weights that is easy, cost-effective, and also compact.
The device, according to embodiments of the present invention, has unbalance weights which are mounted on the particular main shaft so they are rotatable thereon. In addition, it has a coupling, which comprises a transmission medium connected rotationally fixed to the main shaft. This transmission medium is composed so that, on the one hand, it acts as a driver on the unbalance weights and, on the other hand, it causes pivoting of the unbalance weights in opposite directions upon adjustment of the oscillation amplitude of the exciter force.
The transmission medium of the coupling according to the invention assumes essentially two functions. On the one hand, it is used as the driver for the unbalance weights, which are situated adjacent, so that these unbalance weights rotate synchronously and in the same direction with the main shaft in normal operation, i.e., when a fixed setting has been selected for the oscillation amplitude of the exciter force. In addition, the transmission medium causes pivoting in opposite directions of the adjacent unbalance weights in the event of desired change of the angles of the unbalance weights, in order to change the oscillation amplitude of the exciter force during the running of the device.
Inter alia, great advantages are achieved in regard to the compactness of the entire device, the robustness of the coupling, and simple and rapid adjustment capability. Furthermore, production costs may be reduced thanks to the use of simple and identical components. The device is preferably to be used for generating a circular oscillation using a shaft or a directional oscillation, i.e., using at least two main shafts rotating in opposite directions.
In an advantageous embodiment of the present invention, the coupling comprises a device having gearing parts, preferably having bevel gears, in particular having at least one pinion and two crown wheels, one unbalance weight having one crown wheel in each case and the transmission medium being the at least one pinion, which is engaged with the two crown wheels. Crown wheel/pinion pairs have proven to be particularly suitable for fulfilling the features characterized in the independent claims.
It is particularly expedient for the coupling to have multiple transmission media, each situated offset by a preferably equal angle. Two transmission media are preferably used for reasons of symmetrical force distribution. However, depending on the application, more than two transmission media may also be used.
The transmission media are preferably situated so they are rotatable on a transmission medium carrier and have a rotational axis which perpendicularly intersects the rotational axis of the main shaft. Through this condition, the functions of the transmission medium, namely the driver function and the function of the rotational direction reversal upon adjustment, are made easier. However, other embodiments are also possible.
The main shaft preferably has at least one transverse hole for receiving the transmission medium carrier. Using the transverse hole, the transmission medium carrier can be inserted through the main shaft and subsequently equipped from both sides with transmission media, in particular bevel gears, and further parts.
According to a preferred embodiment, means, in particular axial bearings, for absorbing centrifugal forces, which are generated by the transmission medium, are situated on the transmission medium carrier. Due to the compact embodiment of the transmission medium, lesser centrifugal forces are generated than in typical devices in any case. Nonetheless, small axial ball bearings suggest themselves for absorbing centrifugal forces, in order to increase the operational reliability and smooth running still further.
It has proven to be advantageous for the transmission medium carriers to be mounted floating on the transmission medium carrier. Slight movements of the transmission medium along the longitudinal axis of the transmission medium carrier are thus possible. The transmission medium carrier is thus protected from excessive strain as a result of bending torques and tensions.
A further aspect of the present invention is that only one of the unbalance weights is connected to an adjustment unit. It is thus possible to adjust all unbalance weights situated on the same main shaft exactly using the adjustment of a single weight.
A further preferred embodiment of the present invention provides that the main shaft has multiple unbalance weight pairs each having two unbalance weights and a coupling situated between these unbalance weights. All unbalance weights may have the same size and mass. In the event of equal mass of the unbalance weights, the support torques cancel out mutually over the transmission medium carrier. The required support and adjustment forces are thus very low. Depending on the application, arbitrarily many unbalance weight pairs may be situated on one main shaft.
In a particularly preferred embodiment, the unbalance weight pairs are connected in series in that adjacent unbalance weights of the unbalance weight pairs are each connected in phase to one another. In this context, in phase is understood to mean that the angles of these unbalance weights relative to the main shaft are equal. Therefore, the phase difference is understood as the difference of the angles of the unbalance weights to one another.
It is particularly advantageous if the main shaft has an even number of unbalance weight pairs, which are connected in series. For example, if two, four, or six unbalance weight pairs (i.e., four, six, or eight unbalance weights having corresponding couplings) are connected in series on one main shaft, operation of the device free of tilting torque is always ensured, because the angles of the unbalance weights on the left and right are symmetrical relative to the center of gravity of the main shaft.
The unbalance weights of the device according to the invention preferably have means for axial play reduction and reduction of the tooth flank play. These means may be spring elements, for example.
According to a further embodiment of the present invention, the adjustment units of the two parallel main shafts are operationally linked. Because the adjustment sleeves of the adjustment units are synchronized with one another via directly meshing spur gears, for example, and are connected so they are pivotable in opposite directions, for example, in hydraulic adjustment units, single-acting cylinders may also be used instead of double-acting cylinders for one shaft in each case.
The device preferably provides an oil pump for lubricating the gearings and the roller bearings. The oil level in the housing can be reduced by the efficient metering using a sprinkler pipe. The performance loss because of the splashing of the unbalance weights in the oil bath is thus reduced.
Furthermore, it is advantageous to implement the device as pivotable using a pivot drive located outside the housing. The effective angle of the device according to the invention can thus be adapted as needed.
In addition, the device may have means for detecting the current position of the unbalance weights, in particular sensors for detecting the relative phase difference of the unbalance weights to be adjusted. It is thus also possible to implement a frequency adjustment while maintaining a specific centrifugal force.
A great advantage of the invention is the high degree of compactness. The device may thus be installed without problems and with only little effort even in already existing mass-produced machines.
The invention is explained in greater detail hereafter on the basis of drawings. In the schematic figures:
The adjustment unit 30 has an adjustment sleeve 31, which is connected rotationally fixed to the first unbalance weight 12 using an axial lock, e.g., via screws 36. The inner wall of the adjustment sleeve 31 is provided with two spiral grooves 32, which are situated offset by 180°. The adjustment pin 33, which is guided in an oblong hole 39 in the main shaft 10, engages in the spiral grooves 32. An axial movement of the adjustment piston 34, which is implemented in this exemplary embodiment using a single-acting hydraulic cylinder, thus results in a rotating movement of the adjustment sleeve 31 and thus of the unbalance weight 12. In the angles of the unbalance weights 12, 13 shown in
The adjustment according to the invention of the unbalance weights 12, 13 is described in greater detail on the basis of
The crown wheel 43, which is connected fixedly to the unbalance weight 12, rotates like the unbalance weight 12 in the arrow direction 102. The pinions 41, 42, which are situated so they are rotatable on a transmission medium carrier 45 and are engaged with the crown wheel 43 via the bevel gearing, the transmission medium carrier 45 being connected rotationally fixed to the main shaft 10 in a transverse hole 49, are thus rotated. The rotation of the pinions 41, 42 occurs in the indicated arrow directions 103, 104, i.e., clockwise, when the rotation is observed from the axial bearings 48 of the pinion 42 in the direction of the positive z axis. The rotation of the pinions 41, 42 causes the pivoting of the crown wheel 44 and thus also of the unbalance weight 13. However, because of the implementation of the coupling 40 using bevel gears, i.e., using crown wheels 43, 44 and pinions 41, 42, the rotational direction of the unbalance weight 13 (arrow direction 105) is opposite to the rotational direction of the unbalance weight 12.
It has thus been shown that with the aid of the coupling 40, a very compact and simple adjustment of the angles of the unbalance weights 12, 13 is achieved. The pivoting of the unbalance weight 12 by 90° relative to its starting position in relation to the unbalance shaft 10, for example, also causes a pivot of the unbalance weight 13 by 90°, but in the opposite rotational direction, so that the unbalance weights 12, 13 pivot toward or away from one another by 180° relative to one another. The spiral grooves 32 of the adjustment sleeve 31 are designed so that the adjustment sleeve 31 is rotatable from a position shown in
The pivoting of the unbalance weights 12, 13 is usually performed in operation during the rotation of the main shaft 10. In the event of a fixedly set phase difference of the unbalance weights 12, 13, the unbalance weights 12 and 13, which are mounted so they are rotatable using roller bearings 14, 15, are driven with the pinions 41, 42 via the transmission medium 46, in this case via the gearing. The pinions are stationary. The connection via the gearing is thus to be viewed as a static connection. The set unbalance weights 12, 13 rotate in the same direction as the main shaft. A great advantage of the device according to the invention is clear in this case. Because of the implementation of the coupling 40 using crown wheels 43, 44 and pinions 41, 42, the mass inertias of the unbalance weights 12, 13 occurring during the rotation of the main shaft 10 are mutually supported via the pinions 41, 42, so that no undesired pivoting of the unbalance weights 12, 13 can occur. The coupling 40 including the transmission medium 46 promotes a type of self-locking. Furthermore, it follows that the transmission medium carrier 45 must only absorb minimal support forces and support torques because of the symmetrical engagement of the gearing parts in relation to the axis of symmetry of the transmission medium carrier 45, so that great advantages are achieved in regard to the service life and robustness of the coupling 40 according to the invention. In addition, the gearing can be implemented easily and cost-effectively as forge or cast gearing parts, for example.
The adjustment of the oscillation amplitude of the exciter force in operation using opposing pivoting of the unbalance weights 12, 13 is to be viewed as a superposition of the partial movements rotation of the unbalance weights 12, 13 at the speed of the unbalance shaft 10 and pivoting of the unbalance weights 12, 13 in opposite directions by a desired angle amount.
In order to reach the angles of the unbalance weights 12, 13, 22, 23 (maximum exciter force) shown in
A great advantage with the configuration of an even number of unbalance weight pairs 11, 21 connected in series on one main shaft 10 is that the roller bearings 28, 29 of the unbalance shaft 10 are not strained by undesired tilting torques thanks to the approximately symmetrical layout of the unbalance shaft 10 in relation to the center of the unbalance shaft 10.
With the aid of the device according to the invention, the oscillation amplitude of the exciter force can easily and rapidly be adjusted continuously and during the rotation of the shaft through the pivoting of the unbalance weights from a minimal force, i.e., 0 kN, to a maximum force, such as 174 kN. It has proven to be particularly advantageous for the unbalance weights 12, 13, 22, 23 and 62, 63, 65, 66 to remain in the angles shown in
In the same way, upon shutdown or reversal of the machine having the device 1 according to the invention, the unbalance weights are first pivoted at rated speed into the zero position, so that no exciter forces are generated and subsequently the machine is shutdown or reversed. Undesired resonance ranges are avoided by the continuous operation of the device according to the invention at rated speed. Thus, no tumbling of the roller body occurs. If the device according to the invention is used for soil-compacting machines, for example, undesired cross grooves may be avoided, so that the quality of the compaction may be improved overall. The possibility of rapid and comfortable adaptation of the exciter force to the local conditions also contributes to the improvement. Because of the compactness, the device 1 according to the invention may be installed without problems even in already existing mass-produced machines. Through the adaptation of the compaction performance to the substrate, a noise reduction is achieved for both the surroundings and also the driver. Furthermore, the oscillation strain of the machine structure is significantly decreased.
With the aid of the example according to the invention shown in
The many features and advantages of the invention are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the invention.
Number | Date | Country | Kind |
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102008050576.5 | Oct 2008 | DE | national |