Soil compactor and method for operating a soil compactor

Abstract

A soil compactor is described. The soil compactor includes at least two vibrating compacting rollers rotatable about a respective roller axis of rotation. The soil compactor further includes a vibration excitation arrangement assigned to each vibrating compacting roller of the at least two vibrating compacting rollers for generating a vibrating movement of the at least two vibrating compacting rollers. The soil compactor also includes a sensor arrangement assigned to the soil compactor for providing a feedback signal indicative of sound or a structural vibration of the soil compactor. The soil compactor yet further includes a control unit receiving the feedback signal for controlling at least one vibration excitation arrangement, based on the feedback signal, such as to act on a phase offset of the vibrating movements of the at least two vibrating compacting rollers with respect to one another.

Claims

1. A soil compactor, comprising: two vibrating compacting rollers arranged following each other in the direction of a roller axis of rotation and being rotatable about the same roller axis of rotation, a vibration excitation arrangement assigned to each one of the at least two vibrating compacting rollers for generating a vibrating movement of the at least two vibrating compacting rollers, a vibration detection arrangement assigned to each one of the two vibrating compacting rollers for providing vibration variables representing the vibrating movement of each one of the two vibrating compacting rollers, wherein the vibration detection arrangement is in association with each one of the two vibrating compacting rollers and includes at least one accelerometer for detecting an acceleration of each one of the two vibrating compacting rollers, a sensor arrangement assigned to the soil compactor for providing a feedback signal indicative of a structural vibration of the soil compactor, and a control unit for controlling one of the vibration excitation arrangements based on the vibration variables provided by the vibration detection arrangement with respect to the vibrating compacting rollers in such a way that the vibrating movements of the two vibrating compacting rollers have a predefined phase offset relative to one another and for receiving the feedback signal from the sensor arrangement for controlling the one of the vibration excitation arrangements, based on the feedback signal, such as to act on the predefined phase offset of the vibrating movements of the two vibrating compacting rollers with respect to one another, wherein each one of the vibration excitation arrangements assigned to the two vibrating compacting rollers comprises an inertial mass arrangement and an inertial mass drive, each one of the inertial mass drives comprising a drive motor, and each one of the inertial mass arrangements comprising at least one inertial mass drivable by one of the drive motors to rotate about an inertial mass axis of rotation, wherein each drive motor is a hydraulic motor, wherein only one hydraulic pump is provided for supplying all the hydraulic motors serially connected to the hydraulic pump with pressurized fluid, and wherein, for adjusting the phase offset of the vibrating movements of the vibration excitation arrangements assigned to the two vibrating compacting rollers, the control unit is arranged for controlling a bypass valve associated with the hydraulic motor of the one of the vibration excitation arrangements for adjusting the amount of pressurized fluid used in this hydraulic motor.

2. The soil compactor according to claim 1, wherein a vibration variable of the vibration variables has an essentially periodic curve.

3. The soil compactor according to claim 1, wherein all pressurized fluid passing through a first one of the hydraulic motors serially connected to the hydraulic pump also passes through a second one of the hydraulic motors.

4. The soil compactor according to claim 1, wherein the hydraulic pump is a variable hydraulic motor.

5. A method for operating a soil compactor having at least two vibrating compacting rollers, wherein the at least two vibrating compacting rollers are arranged following each other in the direction of a roller axis of rotation, rotatable about the same roller axis of rotation and are excitable to implement a vibrating movement by a respective vibration excitation arrangement, comprising: detecting vibration variables by a vibration detection arrangement assigned to each one of the two vibrating compacting rollers; representing the vibrating movement of each of the vibrating compacting rollers; controlling one of the vibration excitation arrangements based on the vibration variables; detecting a structural vibration of the soil compactor; providing a feedback signal indicative of the structural vibration of the soil compactor; controlling one of the vibration excitation arrangements assigned to each of the two vibrating compacting rollers based on the vibration variables provided by the vibration detection arrangement with respect to the vibrating compacting rollers in such a way that the vibrating movements of the two vibrating compacting rollers have a predefined phase offset relative to one another providing each one of the vibration excitation arrangements assigned to the two vibrating compacting rollers with an inertial mass arrangement and an inertial mass drive, wherein each one of the inertial mass drives comprises a drive motor, and each one of the inertial mass arrangements comprises at least one inertial mass; driving each of said at least one inertial mass by one of the drive motors to rotate said inertial mass about an inertial mass axis of rotation, wherein each rive motor is a hydraulic motor; supplying all the hydraulic motors, which are serially connected to only a single hydraulic pump, with pressurized fluid; adjusting the phase offset of the vibrating movements of the vibration excitation arrangements assigned to the two vibrating compacting rollers; and controlling a bypass valve associated with the hydraulic motor of the one of the vibration excitation arrangements for adjusting the amount of pressurized fluid used in the hydraulic motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is subsequently described in detail with reference to the appended figures.

(2) FIG. 1 shows a soil compactor with two vibrating compacting rollers in a side view;

(3) FIG. 2 shows in perspectives a) and b) the two vibrating compacting rollers of the soil compactor from FIG. 1 with the assigned vibration excitation arrangements;

(4) FIG. 3 shows the two vibrating compacting rollers with the assigned inertial masses in a schematic side view;

(5) FIG. 4 shows the temporal curve of the accelerations of the vibrating compacting rollers occurring in the vibrating compacting rollers of the soil compactor from FIG. 1;

(6) FIG. 5 shows a principle representation of two adjacent vibrating compacting rollers rotatable about a common roller axis of rotation with the assigned vibration excitation arrangements.

DETAILED DESCRIPTION

(7) A soil compactor for compacting a substrate 10 is shown in FIG. 1, referenced as a whole with 12. Soil compactor 12 has two vibrating compacting rollers 14, 16 arranged sequentially in a soil compactor longitudinal direction L, which are rotatable about roller axes of rotation A.sub.1, A.sub.2 spaced apart from one another in soil compactor longitudinal direction L. A roller drive may be assigned to at least one of these two vibrating compacting rollers 14, 16 in order to move soil compactor 12 to implement compacting processes, wherein in the course of this movement, two vibrating compacting rollers 14, 16 rotate about their roller axes of rotation A.sub.1, A.sub.2 and thereby roll over substrate 10. To steer soil compactor 12, vibrating compacting rollers 14, 16, generally referred to as tires, may be pivotable at a compactor frame 18, referenced with 18 and also having a driver's cab 20, about, for example, pivot axes oriented essentially horizontally.

(8) FIG. 2 shows in two depictions a) and b) two vibrating compacting rollers 14, 16 with a vibration excitation arrangement 22 or 24 respectively assigned. Vibration excitation arrangement 22 of vibrating compacting roller 14 comprises an inertial mass arrangement 26 arranged, for example, in the interior of vibrating compacting roller 14 and having at least one inertial mass rotatable about an inertial mass axis of rotation 28.

(9) It should be assumed, for example, that vibration excitation arrangement 22, likewise also vibration excitation arrangement 24, is provided to excite respectively assigned vibrating compacting roller 14, 16 to implement a vibrating movement, thus an vibrating movement back and forth oriented essentially in a vertical direction or orthogonal to the substrate to be compacted. In this case, the at least one inertial mass is generally rotatable about an inertial mass axis of rotation which also essentially corresponds to the axis of rotation of the vibrating compacting roller.

(10) In order to set at least one inertial mass 28 of inertial mass arrangement 26 into motion, thus to drive it to rotate about the respective inertial mass axis of rotation, by way of example here roller axis of rotation A.sub.1, vibration excitation arrangement 22 additionally has an inertial mass drive 30. Inertial mass drive 30 comprises in turn a drive motor 32, designed as a hydraulic motor in the example shown, and a hydraulic pump 34 supplying this drive motor 32 or hydraulic motor with pressurized fluid.

(11) Inertial mass drive 30 is controlled by a control arrangement, referenced as a whole with 36, which controls, for example, hydraulic pump 34 in order to drive the output of pressurized fluid at a predefined output amount or a predefined pressurized fluid, so that drive motor 32 or the hydraulic motor is correspondingly also set into operation and drives the at least one inertial mass 28 to rotate. Hydraulic pump 34 in the example shown in FIG. 2 is thereby a variable hydraulic pump, thus a hydraulic pump whose conveying amount or conveying pressure is adjustable. An increase of the pressurized fluid conveying amount or of the pressure of the pressurized fluid emitted by hydraulic pump 34 leads to a corresponding increase of the speed of a motor shaft (not shown) of the hydraulic motor or drive motor 32 and correspondingly also to a higher speed of the at least one inertial mass 28, with the result that compacting roller 14 set thereby into vibrating movement is excited to vibrate at a correspondingly changed frequency or vibrates at a corresponding frequency.

(12) To detect this vibrating movement of vibrating compacting roller 14, a vibration detection arrangement, referenced as a whole with 38, is provided. This may, for example, comprise at least one accelerometer 40 which detects, for example, the acceleration of compacting roller 14 in the area of roller axis of rotation A.sub.1, for example in the area of a roller bearing, wherein, in the embodiment depicted of a vibrating compacting roller 14 excited to vibration, accelerometer 40 is designed essentially to detect a vibrating movement in that movement direction in which compacting roller 14 is excited into vibrating movement, thus essentially in an up and down direction. Accelerometer 40 provides an acceleration signal, representing the vibrating movement of vibrating compacting roller 14 and depicting a vibration variable, to control arrangement 36. In the subsequently described way, control arrangement 36 may control inertial mass drive 30, in particular hydraulic pump 34, based on this acceleration signal representing a vibration variable, in order to influence the operation of inertial mass arrangement 26 in a corresponding way.

(13) With reference to vibrating compacting roller 16 depicted in FIG. 2b), it is stated that vibration excitation arrangement 24 assigned to the same also comprises an inertial mass arrangement 42 with at least one inertial mass 44 rotatable about an inertial mass axis of rotation, wherein in this example as well, vibration excitation arrangement 24 is designed to generate a vibrating movement of vibrating compacting roller 16 and consequently the at least one inertial mass 28 is rotated about an inertial mass axis of rotation generally corresponding to roller axis of rotation A.sub.2. To generate this rotational movement, an inertial mass drive 46 with a drive motor 48 designed as a hydraulic motor and a variable hydraulic pump 52 is assigned to inertial mass arrangement 42. This hydraulic pump is controlled by a control arrangement 52. Control arrangement 52 may be designed separately from control arrangement 36, yet may be connected to the same for the exchange of information in order to be able to operate two vibration excitation arrangements 22, 24 in a way coordinated with one another. Two control arrangements 36, 52 may, however, also basically be combined in one and the same control arrangement and be designed to control two out-of-balance drives 30, 46.

(14) Reference is made to the fact that these types of control arrangements, used in the context of a soil compactor according to the invention, may be provided in a control device or designed as such. They may, for example, comprise processors designed as microprocessors or microcontrollers and may be programmed permanently or as rewritable with programs suitable for executing the control measures. They may have input connections to which the assigned sensors, in particular accelerometers, may be connected to supply the output signals of the same, and may have output connections to which control lines leading to the respective system areas to be controlled, for example the hydraulic pumps or hydraulic motors, may be connected.

(15) A vibration detection arrangement 54 with at least one accelerometer 56 is also assigned to vibrating compacting roller 16, said accelerometer outputs an acceleration signal, corresponding to the vibrating movement of compacting roller 16, which movement is cause by at least one inertial mass 44 set into rotation, as a vibration variable to control arrangement 52. In this case as well, for example, accelerometer 56 may detect the acceleration of compacting roller 16 in the area of a roller bearing of the same. Reference is be made here, however, that, for example accelerometers provided in the interior of vibrating compacting rollers 14, 16, for example on a roller cover, may be used to detect the acceleration and consequently the vibrating movement of vibrating compacting roller 14, 16. In addition, multiple accelerometers of this type may be respectively assigned to vibrating compacting rollers 14, 16, in order to respectively generate a vibration variable from their output signals, said vibration variable representing the vibrating movement of said vibrating compacting roller 14, 16, for example, in control arrangements 36, 52, and to use the vibration variable to control inertial mass drives 30, 46.

(16) FIG. 3 principally shows a depiction of two vibrating compacting rollers 14, 16 with inertial mass arrangements 26 or 42 assigned to the same. Two inertial masses 28, 44, which may be set into rotation about the respective compacting roller axis of rotation A.sub.1 or A.sub.2, are depicted such that they have an angle offset a to one another; however basically rotated in the same direction.

(17) Acceleration signals B.sub.1, B.sub.2 are generated by accelerometers 40, 56 detecting the vibrating movements of vibrating compacting rollers 14, 16, said acceleration signals are assigned to inertial masses 28, 44 positioned thus relative to one another, the curve of said acceleration signals is shown in FIG. 4, in particular in the case that two vibration excitation arrangements 22, 24 are essentially structurally identical to one another and basically identical, thus in particular are operated with the same speed as their inertial masses 28, 44, then two acceleration signals B.sub.1 and B.sub.2, which represent the temporal curve of the accelerations of vibrating compacting rollers 14, 16, have the same frequency and essentially also the same amplitude of acceleration. However, it is clear that, a phase offset P is present caused by offset a of two inertial masses 28, 44, reference being made here to the angular position of the center of mass of respective inertial masses 28, 44. The size of this phase offset P may be adjusted according to the principles of the present invention so that no beating or other vibration excitations leading in particular to excessive noises may occur due to overlapping of the vibrating movements of two vibrating compacting rollers 14, 16. Phase offset P may, for example, be adjusted depending on the operation of the two vibration excitation arrangements, thus, for example, depending on the speed of inertial masses 28, 44. Alternatively, a sensor arrangement might also be provided on soil compactor 10, which is designed to detect vibrations, for example, sound or structural vibration in the area of soil compactor 10 itself, and thus provides a feedback signal when, during operation of two vibration excitation arrangements 22, 24, there is a risk that an excessive vibration excitation of other system areas occurs due to overlapping of the vibrating movements of two vibrating compacting rollers 14, 16. In this case, inertial mass arrangements 26, 42 may be acted upon in order to influence phase offset P of the vibrating movements caused thereby at two vibrating compacting rollers 14, 16, and thus to counteract an undesired overlapping of this type.

(18) To change phase offset P, the method may proceed, for example, such that starting from a base rotational state of two inertial mass arrangements 26, 42 or of inertial masses 28, 44 of the same, at least one of vibration excitation arrangements 22, 24 is controlled by control arrangement 36 or 52 of inertial mass drive 30 or 46 in such a way that said inertial mass drive functions temporarily, thus in a phase matching operating phase, with a changed speed of respective drive motor 32 or 48. For example, the speed may be increased to correspondingly also increase the speed of inertial mass 28 or 44 thereby set into rotation. An increased speed of one of two inertial masses 28, 44 does indeed lead temporarily to an increased excitation frequency; however, it leads in particular to a change of angle shown in FIG. 3. This operation with changed speed in the phase matching operation phase is continued until desired phase offset P is achieved. If this is the case, then that vibration excitation arrangement 22 and/or 24, which was previously driven at a changed speed with respect to the base rotational state, thus the base speed, is again controlled such that the assigned inertial mass arrangement or its inertial mass rotates again at the base speed, thus in the base rotational state, and consequently two inertial mass arrangements 26, 42 excite assigned vibrating compacting rollers 14, 16 to vibrate again at the frequency corresponding to the base rotational state, for example, to vibrate at the same frequency with one another.

(19) This type of adjustment of phase offset P of the vibrating movements of two vibrating compacting rollers 14, 16 may be carried out repeatedly or continuously as necessary during operation of soil compactor 12, for example, within the context of a control loop in order to guarantee in this way that the occurrence of undesired vibration excitations caused by vibration overlapping is prevented during a changing operating state or operating condition of soil compactor 12, for example, at increasingly strongly compacted substrate and corresponding change of the vibration behavior of vibrating compacting rollers 14, 16.

(20) Although a phase offset P different from zero is shown in FIG. 4, a phase offset P not different from zero may also be advantageous for preventing an adverse overlapping of the vibrating movements, depending on the operating state of soil compactor 12, for example, also depending on the respective vibration amplitudes of vibrating compacting rollers 14, 16. This type of phase offset with the value of zero, which may be adjusted by corresponding control of vibration excitation arrangements 22, 24, is however also basically changeable, thus is also a phase offset in the meaning of the present invention. Furthermore, according to the principles of the present invention, a predetermined phase offset may be defined in that a phase offset, which is disadvantageous with respect to the vibration excitation or vibration overlapping, is not adjusted, or a change is introduced away from this type of undesirable phase offset. If, for example, a phase offset with the value zero, thus an in-phase vibration excitation of the two vibrating compacting rollers, is disadvantageous, then the adjustment of a phase offset arbitrarily different from zero may be interpreted as providing a predetermined phase offset in the meaning of the present invention. Thus, a predetermined phase offset in the meaning of the present invention is also defined by a value range of the phase offset. It is fundamentally relevant for the present invention, that at least one of the vibration excitation arrangements may be influenced in order to be able to actively cause a change of the phase offset.

(21) One alternative embodiment version is shown in FIG. 5. FIG. 5 shows two vibrating compacting rollers 14a, 16a sequential to one another in the direction of a compacting roller axis A and consequently rotatable about the same compacting roller axis of rotation A. A vibration excitation arrangement 22a, 24a with an inertial mass arrangement 26a, 42a respectively and an inertial mass drive 30a, 46a, is assigned to each vibrating compacting roller 14a, 16a. In the example shown in FIG. 5, vibration excitation arrangements 22a, 24a are designed to excite vibrating compacting rollers 14a, 16a to implement an oscillation movement, thus a back and forth movement about roller axis of rotation A, which movement is overlapped by the continuous rotational movement about this roller axis of rotation A occurring during forward movement of a soil compactor. For this purpose, each inertial mass arrangement 26a, 42a has, e.g. at least two inertial masses 28a, 28a, or 44a, 44a which are drivable for rotation about respective inertial mass axes of rotation eccentric to roller axis of rotation A yet parallel to the same. Reference is made here that the structure of this type of inertial mass arrangements 22a, 44a is known in the prior art, for example from WO 2011/064367 A2 discussed at the outset.

(22) Inertial mass drives 30a, 46a, associated with each of inertial mass arrangements 22a, 42a, comprise a drive motor 32a, 48a designed in turn as a hydraulic motor. One common hydraulic pump 34a is assigned to two drive motors 32a, 48a.

(23) In order to be able to provide vibration variables, associated with two vibrating compacting rollers 14a, 16a and representing their vibrating movement, a vibration detection arrangement 38a or 54a is respectively provided, in each case comprising, for example, one or at least one accelerometer 40a or 56a. These are designed in the case depicted for detecting a peripheral acceleration of assigned vibrating compacting roller 14a, 16a, and may, for example be provided on the inner periphery of a respective roller cover or another component or aggregate rotating with the vibrating compacting roller about roller axis of rotation A. The accelerometers 40a, 56a supply their acceleration signals to control arrangement 36a. Control arrangement 36a is basically designed to control two vibration arrangements 22a, 24a to set these into operation. For this purpose, for example, control arrangement 36a may be in a control connection to hydraulic pump 34a. Furthermore, in the embodiment shown, control arrangement 36a is in control connection to drive motor 32a of vibration excitation arrangement 22a. For this purpose, for example, drive motor 32a designed as a variable hydraulic motor in this embodiment may have a bypass valve 58a which is under the control of control arrangement 36a and is able, according to the control, to adjust the amount of pressurized fluid used in hydraulic motor 32a, thus to adjust its absorption volumes such that an adjustment of the speed of a motor shaft of hydraulic motor 32a is also correspondingly carried out.

(24) To set or adjust phase offset P, the operation of inertial mass drive 30a may be influenced in the previously described way, while, for example, inertial mass drive 46a of vibration excitation arrangement 24a is allowed to operate unchanged, in particular, the hydraulic pump also remains unchanged in operation. Basically, however, hydraulic pump 34a in this embodiment may be designed with variable conveying volumes in order to be able to thus also change the speed of hydraulic motor 48a, or to change the speeds of two hydraulic motors or drive motors 32a, 48a through correspondingly changed control of hydraulic pump 34a. The drive motor or hydraulic motor 48a may also be designed as a variable motor.

(25) The configuration of vibration excitation arrangements 22a, 24a, shown in FIG. 5 with a common hydraulic pump 34a acting for two drive motors 32a, 46a, is particularly advantageous if two vibrating compacting rollers 14a, 16a are arranged adjacent to one another and thus are easily coupled to this hydraulic system. If the two vibrating compacting rollers to be coordinated in their phase angles are provided at different areas of a soil compactor, as is shown in FIG. 1, hydraulic systems decoupled from one another are advantageously used.

(26) Soil compactor 12 of FIG. 1 may also be designed in such a way that in one of the end areas thereof, vibrating compacting rollers 14a, 16a, shown in FIG. 5, are provided adjacent to one another, whereas at the other end area, a compacting roller is provided which is basically not excited to implement a vibrating movement. Basically, however, a vibrating compacting roller or two adjacent vibrating compacting rollers may also be used such that more than two vibrating compacting rollers are also used on one and the same soil compactor and may be coordinated to one another with respect to the phase angle of their vibration excitations.