Ground processing machine

Abstract

To provide a ground processing machine that can avoid the occurrence of slip conditions in one or more drive roll segments in the context of a hydraulic drive system that is structurally simple and efficiently utilizes the energy used.SOLUTION: A first fluid connection 28 of a first traction hydraulic pump P1 is connected or connectable to a first fluid connection 30 of a first traction hydraulic motor M1 and a first fluid connection 32 of a second traction hydraulic motor M2 by a first hydraulic line L1, and a first fluid connection 34 of a second traction hydraulic pump P2 is connected or connectable to a first fluid connection 36 of a third traction hydraulic motor M3 and a first fluid connection 38 of a fourth traction hydraulic motor M4 by a second hydraulic line L2.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a geotechnical machine including two drive rolls arranged continuously in the longitudinal direction of the machine and rotatable about their respective rotation axes, each drive roll including two drive roll segments arranged continuously in the direction of the arranged rotation axis, and a hydraulic drive system for the drive roll.

Background Art

[0002] In such a geotechnical machine configured as, for example, a soil compactor, in the case where slip occurs in one or more drive roll segments, in order to be able to continue transmitting torque through the other drive roll segments, in the slip state of the drive roll segments, when excessive fluid outflow occurs through a hydraulic drive motor arranged in such a drive roll segment, the fluid supply to the drive roll segment is shut off or restricted, and as a result, a diverter is known to be used to maintain a sufficient supply of fluid to the non-slip drive rolls.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to provide a geotechnical machine that can avoid the occurrence of a slip state in one or more drive roll segments in an aspect of a hydraulic drive system that is structurally simple and efficiently utilizes the energy used.

Means for Solving the Problems

[0004] According to the present invention, this problem is solved by a geotechnical machine including two drive rolls arranged continuously in the longitudinal direction of the machine and rotatable about their respective rotation axes, each drive roll including two drive roll segments arranged continuously in the direction of the arranged rotation axis, and a hydraulic drive system for the drive roll, and the hydraulic system is - A first traction hydraulic motor disposed in a first drive roll segment of two drive rolls, - A second traction hydraulic motor disposed in a second drive roll segment of two drive rolls, - A third traction hydraulic motor disposed in a third drive roll segment of two drive rolls, - A fourth traction hydraulic motor disposed in a fourth drive roll segment of two drive rolls, - A first traction hydraulic pump, - A second traction hydraulic pump, - At least one drive motor for driving the first traction hydraulic pump and the second traction hydraulic pump to transfer the working fluid to the traction hydraulic motor, - The first fluid connection portion of the first traction hydraulic pump is connected or connectable by a first hydraulic line to the first fluid connection portion of the first traction hydraulic motor and the first fluid connection portion of the second traction hydraulic motor, - The first fluid connection portion of the second traction hydraulic pump is connected or connectable by a second hydraulic line to the first fluid connection portion of the third traction hydraulic motor and the first fluid connection portion of the fourth traction hydraulic motor, - The second fluid connection portion of the first traction hydraulic pump is connected or connectable by a third hydraulic line to the second fluid connection portion of the second traction hydraulic motor and the second fluid connection portion of the third traction hydraulic motor, - The second fluid connection portion of the second traction hydraulic pump is connected or connectable by a fourth hydraulic line to the second fluid connection portion of the first traction hydraulic motor and the second fluid connection portion of the fourth traction hydraulic motor.

[0005] In the earthwork machine configured according to the present invention, the traction hydraulic motors disposed in different drive roll segments are connected to two traction hydraulic pumps by intersecting on the outflow side, regardless of the fluid flow direction, and thus regardless of the rotational direction in which the traction hydraulic motors operate. This means that two traction hydraulic motors connected to one of the two traction hydraulic pumps on the inflow side are not both connected to the traction hydraulic pump on the outflow side. One of the two traction hydraulic motors connected to the same traction hydraulic pump on the inflow side is connected to the other traction hydraulic pump on the outflow side together with the other of the traction hydraulic motors.

[0006] As a result, when slip occurs in one of the drive roll segments, the relatively large amount of fluid flowing out through the traction hydraulic motor disposed in the drive roll segment causes the traction hydraulic pump connected to the outflow side of the traction hydraulic motor to receive only an amount of fluid determined by its rotational speed even in a slip state. Therefore, the amount of fluid flowing out through the traction hydraulic motor of the slipping drive roll segment is prevented by being generally limited by the amount of fluid discharged by the traction hydraulic motor connected to the same traction hydraulic pump on the outflow side together with the traction hydraulic motor.

[0007] Excessive outflow of fluid through a traction hydraulic motor disposed on a slipping drive roll segment is prevented by this intersecting connection on the outflow side between the traction hydraulic motor and the traction hydraulic pump without the need to provide a flow divider. Thereby, the configuration of the hydraulic drive system becomes clearly simpler, and generally a flow divider causes energy loss, so that the energy supplied to drive the traction hydraulic pump can be used more efficiently. This is particularly advantageous in an electro-hydraulic drive system where the traction hydraulic pump is driven by at least one electric drive motor and the amount of electrical energy that can be received by the energy storage device, and thus the range of use or the operating time of the earthmoving machine is also limited.

[0008] In order to enable the same rotational speed to be achieved with all traction hydraulic motors, in a hydraulic drive system with a simple structure, to ensure that two traction hydraulic pumps transfer substantially the same amount of fluid, the two traction hydraulic pumps may be driven by a common drive motor for transferring the working fluid, or / and the two traction hydraulic pumps can have the same discharge capacity. Further, all traction hydraulic motors can have the same displacement. At this time, the discharge capacity of the traction hydraulic pump may be, for example, the amount of fluid discharged per revolution of the traction hydraulic pump, and the displacement of the traction hydraulic motor may be the amount of fluid received per revolution of the traction hydraulic motor.

[0009] To enable the earthmoving machine to be operated electro-hydraulically, at least one drive motor may be an electric motor.

[0010] Particularly in the case of an electro-hydraulic drive system, i.e., when one or more drive motors are configured as electric motors, in order to obtain a hydraulic drive system with a simple structure, it is advantageous if each traction hydraulic pump is a pump with a fixed displacement, and / or each traction hydraulic motor is a motor with a fixed displacement. This means that in order to obtain different rotational speeds of the earthmoving machine and thus different traveling speeds, it is not necessary to adjust the position of the traction hydraulic pump or the traction hydraulic motor during operation. This can be achieved simply by changing the rotational speed of the drive motor.

[0011] An extended network of traction hydraulic motors for further improving slip control is - A first valve unit arranged at the second fluid connection of the first traction hydraulic motor for selectively establishing and interrupting the connection between the second fluid connection of the first traction hydraulic motor and the third hydraulic line, and a second valve unit for selectively establishing and interrupting the connection between the second fluid connection of the first traction hydraulic motor and the fourth hydraulic line are provided, - A third valve unit arranged at the second fluid connection of the second traction hydraulic motor for selectively establishing and interrupting the connection between the second fluid connection of the second traction hydraulic motor and the third hydraulic line, and a fourth valve unit for selectively establishing and interrupting the connection between the second fluid connection of the second traction hydraulic motor and the fourth hydraulic line are provided, obtained by

[0012] Accordingly, it becomes possible to change the combination of traction hydraulic motors connected to the same traction hydraulic pump on the outflow side depending on which drive roll segment has slip occurring.

[0013] In order to be able to change the cross - connection between the traction hydraulic motor and the traction hydraulic pump as determined according to whether slip occurs in any of the drive roll segments, it is possible to provide a control device for controlling the first valve unit, the second valve unit, the third valve unit and the fourth valve unit. The control device - When the first valve unit for establishing the connection between the second fluid connection of the first traction hydraulic motor and the third hydraulic line and the fourth valve unit for establishing the connection between the second fluid connection of the second traction hydraulic motor and the fourth hydraulic line are operating, the second valve unit for blocking the connection between the second fluid connection of the first traction hydraulic motor and the fourth hydraulic line and the third valve unit for blocking the connection between the second fluid connection of the second traction hydraulic motor and the third hydraulic line are operated. - When the first valve unit for blocking the connection between the second fluid connection of the first traction hydraulic motor and the third hydraulic line and the fourth valve unit for blocking the connection between the second fluid connection of the second traction hydraulic motor and the fourth hydraulic line are operating, the second valve unit for establishing the connection between the second fluid connection of the first traction hydraulic motor and the fourth hydraulic line and the third valve unit for establishing the connection between the second fluid connection of the second traction hydraulic motor and the third hydraulic line are operated. It is configured as follows.

[0014] For example, in order to compensate for fluid leakage in the area of the traction hydraulic motor, a fluid supply device for supplying fluid to at least one of the first fluid line, the second fluid line, the third fluid line and the fourth fluid line can be provided.

[0015] Such a fluid supply device is generally configured to supply fluid to the low-pressure side of a hydraulic circuit, i.e., a hydraulic line that connects a traction hydraulic motor to a traction hydraulic pump on the outflow side, whereby the fluid pressure is maintained at a predetermined level in the region of the line. In interaction with such a fluid supply device, when slip occurs in the drive roll segment, the traction hydraulic motor provided can operate for a short time at a slightly higher rotational speed and thus with a correspondingly larger fluid outflow. Such a larger fluid outflow through the traction hydraulic motor can be compensated for by a smaller fluid supply by the fluid supply device, even when the limit is basically determined by the amount of fluid returned from the other traction hydraulic motor to the same traction hydraulic pump. By this interaction, in the traction hydraulic motor provided in the drive roll segment with traction force loss, the drive torque decreases, and the decreased drive torque corresponds to the maximum drive torque that can be transmitted without slipping through the drive roll segment.

[0016] The first drive roll of the two drive rolls can include a first drive roll segment and a second drive roll segment, and the second drive roll of the two drive rolls can include a third drive roll segment and a fourth drive roll segment.

[0017] By arranging cross-connected traction hydraulic motors as determined in different drive roll segments, in order to reduce the possibility of a situation where two traction hydraulic motors that basically restrict each other's fluid outflow rates simultaneously reach a slip state, in the longitudinal direction of the machine, the first drive roll segment and the third drive roll segment are arranged on the first side of the earthmoving machine, and it is proposed that the second drive roll segment and the fourth drive roll segment be arranged on the second side of the earthmoving machine. By arranging the traction hydraulic motors in the drive roll segments in this way, when traveling on a curve, the traction hydraulic motors connected to each other on the outflow side can have different rotational speeds on the drive roll segment inside the curve and the drive roll segment outside the curve without being blocked from each other by the fluid amounts discharged from the respective traction hydraulic motors.

[0018] When configuring the earthmoving machine as a soil compactor, at least one of the two drive rolls may be an earthmoving roller, and each drive roll segment of at least one drive roll is supplied by a roller segment. Alternatively or additionally, at least one of the two drive rolls can include at least two wheels, and each drive roll segment of at least one drive roll includes at least one wheel. Such drive wheels may be, for example, drive wheels used solely for driving the earthmoving machine and arranged on both sides at the rear of the vehicle, or may be, for example, the pneumatic tires of a pneumatic tire roller arranged in pairs with each other.

[0019] In order to be able to take appropriate measures, such as switching different valve units as determined, when slip occurs, a slip detection device for detecting the slip state of at least one drive roll segment, preferably each drive roll segment, can be provided.

[0020] At this time, the slip detection device may include at least one drive roll segment, preferably a speed sensor disposed on each drive roll segment.

[0021] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. The following are shown:

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0023] FIG. 1 schematically shows a geotechnical machine, generally designated by reference numeral 10, configured as a soil compactor, for example. The geotechnical machine 10 configured as a soil compactor includes two drive rolls 12 and 14 that are continuously arranged in the longitudinal direction R of the machine and each configured as a geotechnical roller. The drive roll 12 is rotatable about a first rotation axis D1, and the drive roll 14 is rotatable about a second rotation axis D2. Two traction hydraulic motors M1, M2 or M3, M4 are disposed on each of the two drive rolls 12 and 14. For example, the traction hydraulic motors M1, M2, M3, M4 disposed on each drive roll 12 or 14 may be arranged at respective axial ends.

[0024] The two drive rolls 12, 14 are configured as a split soil roller, each having drive roll segments 12a, 12b or 14a, 14b. One of the four traction hydraulic motors M1, M2, M3, M4 is disposed on each of the drive roll segments 12a, 12b, 14a, 14b. The two drive roll segments 12a, 12b are driven to rotate around the rotation axis D1 independently of each other by the traction hydraulic motors M1, M2 disposed on the drive roll segments, and the two drive roll segments 14a, 14b can be driven to rotate around the rotation axis D2 independently of each other by the traction hydraulic motors M3, M4 disposed on the drive roll segments.

[0025] FIG. 2 shows an alternative embodiment of the soil working machine 10 configured as a soil roller, for example. The soil working machine 10 in FIG. 2 includes, in one of its longitudinal end regions, a drive roll 12 also configured as a soil roller, and two traction hydraulic motors M1, M2 disposed on the drive roll 12. Also in this embodiment, the drive roll 12 includes two drive roll segments 12a, 12b that can be driven to rotate around the rotation axis D1 independently of each other by the traction hydraulic motors M1, M2 disposed thereon. In the other longitudinal end region of the soil working machine 10, the drive roll 14 includes wheels 16, 18, 20, 22. These wheels may be arranged in pairs, for example, and each pair consisting of wheels 16, 18 or 20, 22 forms drive roll segments 14a, 14b, and the drive roll segments 14a, 14b can be driven to rotate around the rotation axis D2 by the traction hydraulic motor M3 or M4 disposed on the drive roll segments 14a, 14b.

[0026] It should be noted that other types of structures of such geotechnical machinery can also be used in the context of the hydraulic drive system described below. For example, in a geotechnical machine configured as a soil compactor, a pair of drive wheels that respectively form drive roll segments of the drive rolls may be provided at the rear of the vehicle, while at the front of the vehicle, a geotechnical roller divided into roller segments can act as a drive roll. The principle of the present invention is applicable to a geotechnical machine or a soil compactor using a pivot steering method, and also to a geotechnical machine divided into a front part and a rear part of the vehicle.

[0027] FIG. 3 shows a hydraulic drive system 24, and the hydraulic drive system 24 is an electro-hydraulic drive system in the illustrated embodiment and can be used in combination with the geotechnical machine described above with reference to FIGS. 1 and 2, for example.

[0028] The hydraulic drive system 24 includes two traction hydraulic pumps P1, P2 and four traction hydraulic motors M1, M2, M3, M4 in a hydraulic circuit 26. Both of the two traction hydraulic pumps P1, P2 can be driven by a drive motor E configured as an electric motor.

[0029] The first fluid connection portion 28 of the first traction hydraulic pump P1 is connected to the first fluid connection portion 30 of the first traction hydraulic motor M1 and the first fluid connection portion 32 of the second traction hydraulic motor M2 through a first hydraulic line L1. The first fluid connection portion 34 of the second traction hydraulic pump P2 is connected to the first fluid connection portion 36 of the third traction hydraulic motor M3 and the first fluid connection portion 38 of the fourth traction hydraulic motor M4 through a second hydraulic line L2.

[0030] The second fluid connection portion 40 of the first traction hydraulic pump P1 is connected through a third fluid line L3 to the second fluid connection portion 42 of the second traction hydraulic motor M2 and the second fluid connection portion 44 of the third traction hydraulic motor M3. The second fluid connection portion 46 of the second traction hydraulic pump P2 is connected through a fourth fluid line L4 to the second fluid connection portion 48 of the first traction hydraulic motor M1 and the second fluid connection portion 50 of the fourth traction hydraulic motor M4.

[0031] Depending on whether the earthmoving machine 10 should move in either travel direction, for example when moving forward, the drive motor E can be controlled by the control unit 52 such that the traction hydraulic pumps P1, P2 supply fluid to the first hydraulic line L1 or the second hydraulic line L2 at their respective first fluid connection portions 28, 34, and thus supply fluid under high pressure, for example hydraulic oil, to the traction hydraulic motors M1, M2, M3, M4 through the respective first fluid connection portions 30, 32, 36, 38, in a transfer direction in which the traction hydraulic pumps P1, P2 are operated.

[0032] In this state, the traction hydraulic motors M1, M2, M3, M4 discharge the significantly depressurized fluid at their respective second fluid connection portions 48, 42, 44, 50 into the third hydraulic line L3 or the fourth hydraulic line L4, and through this hydraulic line, the fluid flows back to the second fluid connection portions 40, 46 of the traction hydraulic pumps P1, P2.

[0033] When the earthmoving machine 10 is to move in the opposite direction, i.e., for example, in the reverse direction, the drive motor E is controlled such that the traction hydraulic pumps P1, P2 driven by the drive motor E discharge fluid into the third hydraulic line L3 or the fourth hydraulic line L4 through their respective second fluid connections 40, 46. Through the third hydraulic line L3, the fluid transferred by the first traction hydraulic pump P1 flows to the second fluid connections 42, 44 of the second traction hydraulic motor M2 and the third traction hydraulic motor M3. Through the fourth hydraulic line L4, the fluid transferred by the second traction hydraulic pump P2 flows to the second fluid connections 48, 50 of the first traction hydraulic motor M1 and the fourth traction hydraulic motor M4. In this operating state, the first traction hydraulic motor M1 and the second traction hydraulic motor M2 discharge fluid from their first fluid connections 30, 32 through the first hydraulic line L1 to the first fluid connection 28 of the first traction hydraulic pump P1, and the third traction hydraulic motor M3 and the fourth traction hydraulic motor M4 discharge fluid from their first fluid connections 36, 38 through the second fluid line L2 to the first fluid connection 34 of the second traction hydraulic pump P2.

[0034] The fluid leakage occurring, in particular in the regions of the traction hydraulic motors M1, M2, M3, M4, can be compensated by means of a supply device, generally designated by reference numeral 53, which supplies fluid to the low-pressure side of the hydraulic circuit 26. For this purpose, the supply device 53 includes, for example, a supply pump S driven by a drive motor arranged on the supply device 53, which discharges fluid from the fluid tank F and supplies it to the first hydraulic line L1, the second hydraulic line L2, the third hydraulic line L3 or the fourth hydraulic line L4 via four supply valves E1, E2, E3, E4, respectively.

[0035] In the hydraulic drive system 24 shown in FIG. 2, regardless of whether the earthmoving machine 10 moves in any direction or whether the traction hydraulic motors M1, M2, M3, M4 arranged on the different drive roll segments 12a, 12b, 14a, 14b rotate in any direction, two traction hydraulic motors are respectively connected to the same traction hydraulic pump P1 or P2 on the high-pressure side, that is, the inflow side. When fluid is discharged through the first fluid connection portions 28, 34 of the traction hydraulic pumps P1, P2, the traction hydraulic motors M1, M2 are connected to the first traction hydraulic pump P1 on the high-pressure side, and the traction hydraulic motors M3, M4 are connected to the second traction hydraulic pump P2 on the high-pressure side.

[0036] However, on the low-pressure side, that is, the outflow side, each traction hydraulic motor connected to one of the traction hydraulic pumps on the high-pressure side is not necessarily connected to the same traction hydraulic pump. Only one of the traction hydraulic motors connected to the traction hydraulic pump on the high-pressure side is also connected to the traction hydraulic pump on the low-pressure side, while the other traction hydraulic motor is connected to the other traction hydraulic pump on the low-pressure side. In the illustrated embodiment, this means that when fluid is discharged through the first fluid connection portions 28, 34 of the traction hydraulic pumps P1, P2, the second traction hydraulic motor M2 and the third traction hydraulic motor M3 are connected to the first traction hydraulic pump P1 through the third hydraulic line L3, while the first traction hydraulic motor M1 and the fourth traction hydraulic motor M4 are connected to the second traction hydraulic pump P2 through the fourth hydraulic line L4.

[0037] When moving in the reverse direction, i.e., when fluid is discharged through the second fluid connection portions 40, 46 of the traction hydraulic pumps P1, P2 respectively, on the high-pressure side, i.e., through the third hydraulic line L3, the second traction hydraulic motor M2 and the third traction hydraulic motor M3 are connected to the first traction hydraulic pump P1, while through the fourth hydraulic line L4, the first traction hydraulic motor M1 and the fourth traction hydraulic motor M4 are connected to the second traction hydraulic pump P2. In this state, on the low-pressure side, the first traction hydraulic motor M1 and the second traction hydraulic motor M2 are connected to the first traction hydraulic pump P1 through the first hydraulic line L1, while the third traction hydraulic motor M3 and the fourth traction hydraulic motor M4 are connected to the second traction hydraulic pump P2 through the second hydraulic line L2.

[0038] In the case of such a hydraulic drive system 24, in the transfer mode, since the amount of fluid that each traction hydraulic pump P1, P2 can receive on the low-pressure side is only the same as the amount sent out on the high-pressure side, in the cross-connection of this traction hydraulic motor M1, M2, M3, M4 and the traction hydraulic pump P1, P2, it is important that each traction hydraulic pump P1, P2 transfers substantially the same amount of fluid and each traction hydraulic motor M1, M2, M3, M4 receives substantially the same amount of fluid. In particular, when configured as an electro-hydraulic drive system, it is advantageous that the traction hydraulic pumps P1, P2 have a constant discharge volume and the traction hydraulic motors M1, M2, M3, M4 have a constant displacement volume. The pump flow rate can only be changed by changing the drive rotation speed of the drive motor E configured as an electric motor. When the traction hydraulic pumps P1, P2 and the traction hydraulic motors M1, M2, M3, M4 are thus configured to each have the same discharge volume or displacement volume, all the traction hydraulic motors M1, M2, M3, M4 rotate at the same rotation speed, or the drive roll segments 12a, 12b, 14a, 14b respectively arranged on the traction hydraulic motors are driven to rotate at the same rotation speed. For this purpose, it is still necessary that all the drive roll segments 12a, 12b, 14a, 14b have the same diameter. When the drive rolls 12, 14 arranged on different rotation axes D1, D2 have different diameters, especially as shown in FIGS. 1 and 2, when the traction hydraulic motors M1, M2, M3, M4 are arranged on the drive roll segments 12a, 12b, 14a, 14b, on the one hand, traction hydraulic motors with different displacement volumes can be used for the drive roll segments 12a, 12b, and on the other hand, for the drive roll segments 14a, 14b.

[0039] By cross-connecting the traction hydraulic motors M1, M2, M3, and M4, it is ensured that none of the drive roll segments 12a, 12b, 14a, and 14b will be in a slipping state where an excessive amount of fluid flows out through the traction hydraulic motor due to an increase in the rotational speed of the installed traction hydraulic motor. For example, if slipping occurs in the first drive roll segment 12a due to a loss of traction force, the rotational speed of the traction hydraulic motor M1 will correspondingly increase. As a result, the traction hydraulic motor will receive and thus discharge a larger amount of fluid. The first traction hydraulic motor M1 discharges the received fluid into the fourth fluid line L4 when the first traction hydraulic motor M1 receives fluid from the first traction hydraulic pump P1 through, for example, the first hydraulic line L1. And in this state, the fourth traction hydraulic motor M4, which is supplied by the other traction hydraulic pump P2, discharges an amount of fluid corresponding to the normal traction force into the fourth hydraulic line L4. Therefore, the fourth hydraulic line L4 can only receive the amount of fluid that the first traction hydraulic motor M1 would discharge even in a state where there is basically no slip. Thus, the first traction hydraulic motor M1 cannot rotate faster than the other traction hydraulic motors M2, M3, and M4, even in the case of a loss of traction force in the installed first drive roll segment 12a. Therefore, excessive outflow of fluid from the first hydraulic line L1 will not occur.

[0040] However, due to the fluid leakage described above, basically, when a loss of traction force occurs in the installed first drive roll segment 12a, there is a possibility that the first traction hydraulic motor M1 will discharge a larger amount of fluid in a shorter time than in a state where no slip is occurring. The larger amount of fluid supplied to the fourth hydraulic line L4 through the first traction hydraulic motor M1 does not need to be replenished by the supply device 53 to maintain the pressure determined on the low-pressure side of the hydraulic circuit 26.

[0041] When the rotational speed of the first traction hydraulic motor M1 increases in a short time due to such slip, a spontaneous pressure drop is caused on the high-pressure side, that is, in the first hydraulic line L1 in this case. As a result of this pressure drop, the driving torque generated by the first traction hydraulic motor decreases to a value such that the first drive roll segment 12a having a smaller traction force can operate again without slipping. The decrease in the driving torque in the first traction hydraulic motor M1 results in a corresponding decrease in the driving torque of the second traction hydraulic motor M2 to which the same pressure is applied. Basically, since the driving force of the drive motor E is maintained, a correspondingly higher pressure is generated in the second hydraulic line L2 supplied from the second traction hydraulic pump P2, and the traction hydraulic motors M3 and M4 supplied from the second hydraulic line L2 operate with a correspondingly increased driving torque.

[0042] The autonomous adjustment of the driving torque or rotational speed of the drive roll segment when traction loss occurs as described above does not depend on which drive roll segment the traction loss occurs in and in which direction the earthwork machine 10 moves. Since the other traction hydraulic motor that is not supplied from the same traction hydraulic pump is connected to the outflow side of each traction hydraulic motor M1, M2, M3, M4, the traction hydraulic motors are blocked from each other against the increase in rotational speed due to slip.

[0043] Despite this mutual shut-off of the traction hydraulic motors M1, M2, M3, M4 connected to each other on the outflow side, as can be recognized in particular in FIGS. 1, 2 and 3, when the traction hydraulic motors M1, M2, M3, M4 are arranged on the drive roll segments 12a, 12b, 14a, 14b, when traveling on a curve, each pair of drive roll segments 12a, 14a or 12b, 14b on the inner side of the curve may rotate at a lower rotational speed than each pair of drive roll segments 12a, 14a or 12b, 14b on the outer side of the curve. For example, a decrease in the fluid outflow rate of the first traction hydraulic motor M1 due to a decrease in the rotational speed of the drive roll segment 12a is compensated by an increase in the corresponding fluid outflow rate of the fourth traction hydraulic motor M4, and the sum of these fluid outflow rates corresponds again to the sum of the fluid outflow rates of these two traction hydraulic motors M1, M4 that would exist in the case of the same rotational speed. The same applies to each pair of traction hydraulic motors connected to each other on the outflow side when the traction hydraulic motors M2, M3, or other pairs move in the other traveling direction.

[0044] FIG. 4 shows an embodiment of a hydraulic drive system 24 in which the possibility of a slip state occurring in one of the drive roll segments 12a, 12b, 14a, 14b is further reduced. In FIG. 4, it can be recognized, for example, that two valve units V1, V2 or V3, V4 are provided respectively for the first traction hydraulic motor M1 and for the second traction hydraulic motor M2. Through the first valve unit V1, the second fluid connection 48 of the first traction hydraulic motor M1 can be selectively connected to the third hydraulic line L3 or separated from the third hydraulic line L3. Correspondingly, through the second valve unit V2, the second fluid connection 48 of the first traction hydraulic motor M1 can be selectively connected to the fourth hydraulic line L4 or selectively separated from the fourth hydraulic line L4.

[0045] The valve units V1, V2 controlled by the control unit 52 are basically controlled such that when one of the valve units V1, V2 establishes a connection to the second fluid connection 48 of the first traction hydraulic motor M1, the other valve unit shuts off the connection to the arranged hydraulic line. Thus, the second fluid connection 48 of the first traction hydraulic motor M1 is connected to the third fluid line L3 or the fourth fluid line L4.

[0046] The third valve unit V3 arranged in the second traction hydraulic motor M2 establishes or shuts off the connection between the second fluid connection 42 and the third hydraulic line L3. Similarly, the fourth valve unit V4 selectively establishes or shuts off the connection between the second fluid connection 42 of the second traction hydraulic motor M2 and the fourth fluid line L4. The two valve units V3, V4 are also controlled by the control unit 52 such that when one valve unit establishes a connection to the arranged hydraulic line, the other valve unit is in a shut-off state.

[0047] Furthermore, the four valve units V1, V2, V3, V4 are controlled or operated by the control unit 52 so that a state where the two second outlet connections 48, 42 of the traction hydraulic motors M1, M2 are connected to the same hydraulic line L3 or L4 does not occur. As shown in FIG. 3, when the second fluid connection 48 of the first traction hydraulic motor M3 is connected to the fourth hydraulic line L4, the second fluid connection 42 of the second traction hydraulic motor M2 is connected to the third fluid line L3, and vice versa.

[0048] Therefore, the switching states of the valve units V1, V2, V3, V4 shown in FIG. 4 basically correspond to the connection states that cannot be changed in FIG. 3, in which the second fluid connection 48 of the first traction hydraulic motor M1 is connected to the fourth hydraulic line L4 and the second fluid connection 42 of the second traction hydraulic motor M2 is connected to the third fluid line L3.

[0049] In such a state, when a traction loss occurs in two drive roll segments 12a, 14a or 12b, 14b arranged on the same side of the soil compactor 10 with respect to the longitudinal direction R of the machine, that is, on the same side in the lateral direction Q of the machine, a fluid short - circuit may occur in the hydraulic circuit 26. In this case, all the fluid transferred by the traction hydraulic pumps P1, P2 respectively flows out through the traction hydraulic motors arranged on the slipping drive roll segments, but does not flow out through the traction hydraulic motors arranged on the non - slipping drive roll segments.

[0050] To address this problem, in the hydraulic drive system 24 shown in FIG. 4, speed sensors 54, 56, 58, 60 of the slip detection device 62 are provided and arranged on the traction hydraulic motors M1, M2, M3, M4. Through the rotational speed signals emitted by the speed sensors 54, 56, 58, 60, information about in which of the drive roll segments 12a, 14a, 12b, 14b a traction loss is occurring is supplied to the control unit 52.

[0051] For example, in the drive roll segments 12b and 14b, a loss of traction force with corresponding slip occurs simultaneously. In the switching state shown in FIG. 3, when the entire fluid supplied to the second hydraulic line L2 flows out through the fourth traction hydraulic motor M4 and the entire fluid supplied to the first hydraulic line L1 flows out through the second traction hydraulic motor M2, the four valve units V1, V2, V3, V4 can be switched from the switching state shown in FIG. 3. As a result, while the first traction hydraulic motor M1 is connected to the third hydraulic line L3 on the outflow side, the second traction hydraulic motor M2 is connected to the fourth hydraulic line L4 on the outflow side. In this state, the two traction hydraulic motors M2 and M4 arranged in the drive roll segments 12b and 14b having a loss of traction force are connected to each other on the outflow side. Therefore, due to the fact that the second traction hydraulic pump P2 can only receive a determined amount of fluid at its second fluid connection portion 46, the amount of fluid flowing out through these traction hydraulic motors M2 and M4 is generally limited to the amount of fluid flowing through the traction hydraulic motor even in a state where no slip occurs.

[0052] In an alternative embodiment, it is pointed out that the variability introduced by the valve units V1, V2, V3, V4 can also be obtained when the valve units are provided connected to the traction drive motors M3, M4 and the hydraulic lines L3, L4, or when the valve units are connected to the traction hydraulic motors M2, M3 or the traction hydraulic motors M1, M4 and arranged in the first hydraulic line L1 and the second hydraulic line L2, respectively.

Description of Reference Numerals

[0053] 10 Earthmoving machinery, 12, 14 drive rolls, 12a, 12b, 14a, 14b drive roll segments, 16, 18, 20, 22 wheels, 24 hydraulic drive system, 26 hydraulic circuit, 28, 30, 32, 34, 36, 38 first fluid connection parts, 40, 42, 44, 46, 48, 50 second fluid connection parts, 52 control unit, 53 supply device, 54, 56, 58, 60 speed sensors, 62 slip detection device, D1 first rotation axis, D2 second rotation axis, E drive motor, E1, E2, E3, E4 supply valves, F fluid tank, L1 first hydraulic line, first fluid line, L2 second hydraulic line, second fluid line, L3 third fluid line, third fluid line, L4 fourth fluid line, fourth fluid line, M1 first traction hydraulic motor, M2 second traction hydraulic motor, M3 third traction hydraulic motor, M4 fourth traction hydraulic motor, P1 first traction hydraulic pump, P2 second traction hydraulic pump, Q lateral direction of the machine, R longitudinal direction of the machine, S supply pump, V1 first valve unit, V2 second valve unit, V3 third valve unit, V4 fourth valve unit

Claims

1. The rotary shafts (D １ , D ２ Two drive rolls (12, 14) rotatable around the rotation axis (D), each drive roll (12, 14) being disposed on said rotation axis (D １ , D ２ 1. An earth-moving machine comprising: a driving roll (12, 14) including two driving roll segments (12a, 12b, 14a, 14b) arranged successively in a direction of a rotation axis; and a hydraulic drive system (24) for said driving roll (12, 14), the hydraulic drive system (24) comprising: a first traction hydraulic motor (M) arranged on the first drive roll segment (12a) of the two drive rolls (12, 14); １ )and, a second traction hydraulic motor (M) arranged on the second drive roll segment (12b) of the two drive rolls (12, 14); ２ )and, a third traction hydraulic motor (M) arranged on the third drive roll segment (14a) of the two drive rolls (12, 14); ３ )and, a fourth traction hydraulic motor (M) arranged on the fourth drive roll segment (14b) of the two drive rolls (12, 14); ４ )and, - first traction hydraulic pump (P １ )and, - second traction hydraulic pump (P ２ )and, - Traction hydraulic motor (M １ , M. ２ , M. ３ , M. ４ The first traction hydraulic pump (P １ ) and the second traction hydraulic pump (P ２ At least one drive motor (E) for driving the - the first traction hydraulic pump (P １ The first fluid connection (28) of the first hydraulic line (L １ ) by the first traction hydraulic motor (M １ ) and said second traction hydraulic motor (M ２ ) connected or connectable to a first fluid connection (32) of - the second traction hydraulic pump (P ２ The first fluid connection (34) of the second hydraulic line (L ２ ) by the third traction hydraulic motor (M ３ ) and the first fluid connection (36) of the fourth traction hydraulic motor (M ４ ) connected or connectable to a first fluid connection (38) of - the first traction hydraulic pump (P １ The second fluid connection (40) of the third hydraulic line (L ３ ) by the second traction hydraulic motor (M ２ ) and a second fluid connection (42) of a third traction hydraulic motor (M ３ ) connected or connectable to a second fluid connection (44) of - the second traction hydraulic pump (P ２ The second fluid connection (46) of the fourth hydraulic line (L ４ ) by the first traction hydraulic motor (M １ ) and the second fluid connection (48) of the fourth traction hydraulic motor (M ４ ) an earth moving machine connected or connectable to a second fluid connection (50) of said earth moving machine.

2. Both traction hydraulic pumps (P １ , P ２ ) are driven by the common drive motor (E) to transport hydraulic fluid, or / and both traction hydraulic pumps (P １ , P ２ ) have the same discharge volume, or / and all of said traction hydraulic motors (M １ , M. ２ , M. ３ , M. ４ 2. An earth moving machine as claimed in claim 1, wherein:

3. 3. An earth-moving machine according to claim 1 or 2, characterized in that at least one drive motor (E) is an electric motor.

4. Each traction hydraulic pump (P １ , P ２ ) is a pump having a fixed discharge amount, or / and each traction hydraulic motor (M １ , M. ２ , M. ３ , M. ４ 4. An earth moving machine according to claim 1, wherein the motor is a motor having a constant displacement.

5. - first traction hydraulic motor (M １ ) to a second fluid connection (48) of said first traction hydraulic motor (M １ ) and a third hydraulic line (L ３ a first valve unit (V) for selectively establishing and interrupting a connection with the １ ), and the first traction hydraulic motor (M １ ) and a fourth hydraulic line (L ４ a second valve unit (V) for selectively establishing and interrupting a connection with the ２ ) and - second traction hydraulic motor (M ２ ) to a second fluid connection (42) of said second traction hydraulic motor (M ２ ) and a third hydraulic line (L ３ a third valve unit (V) for selectively establishing and interrupting a connection with the ３ ), and the second traction hydraulic motor (M ２ ) and a fourth hydraulic line (L ４ a fourth valve unit (V) for selectively establishing and interrupting a connection with the ４ ) and An earthmoving machine as claimed in any one of claims 1 to 4, characterized in that

6. First valve unit (V), second valve unit (V ２ ), the third valve unit (V) and the fourth valve unit (V ４ A control device (52) is provided for controlling the - first traction hydraulic motor (M １ ) and a third hydraulic line (L ３ said first valve unit (V １ ), and a second traction hydraulic motor (M ２ ) and a fourth hydraulic line (L ４ the fourth valve unit (V ４ ) and the first traction hydraulic motor (M １ ) and the fourth hydraulic line (L ４ The second valve unit (V ２ ), and the second traction hydraulic motor (M ２ ) and the third hydraulic line (L ３ The third valve unit (V ３ ) and operate, said first traction hydraulic motor (M １ the first valve unit (V) for disconnecting the second fluid connection (48) of the second traction hydraulic motor (M) from the third hydraulic line (L3); ２ ) and the fourth hydraulic line (L ４ The fourth valve unit (V ４ ) and the first traction hydraulic motor (M １ ) and the fourth hydraulic line (L ４ said second valve unit (V ２ ), and the second traction hydraulic motor (M ２ the third valve unit (V) for establishing a connection between the second fluid connection (42) of the third hydraulic line (23) and ３ 6. An earth moving machine as claimed in claim 5, configured to operate

7. The first fluid line (L １ ), the second fluid line (L ２ ), the third fluid line (L ３ ) and a fourth fluid line (L ４ 7. An earthmoving machine according to any one of claims 1 to 6, characterized in that a fluid supply device (53) is provided for supplying fluid to at least one fluid line of the at least one hydraulic line of the hydraulic system.

8. 8. An earth-moving machine according to claim 1, characterized in that a first drive roll (12) of the two drive rolls (12, 14) comprises a first drive roll segment (12a) and a second drive roll segment (12b), and a second drive roll (14) of the two drive rolls (12, 14) comprises a third drive roll segment (14a) and a fourth drive roll segment (14b).

9. 9. An earthmoving machine according to claim 8, characterized in that, with respect to the longitudinal direction (R) of the machine, the first driving roll segment (12a) and the third driving roll segment (14a) are arranged on a first side of the earthmoving machine (10) and the second driving roll segment (12b) and the fourth driving roll segment (14b) are arranged on a second side of the earthmoving machine (10).

10. 10. An earth-moving machine according to claim 1, characterized in that at least one of the two drive rolls (12, 14) is an earth-moving roller, each drive roll segment (12a, 12b, 14a, 14b) of the at least one drive roll (12, 14) being supplied by a roller segment, or / and that at least one of the drive rolls (14) comprises at least two wheels (16, 18, 20, 22), each drive roll segment (14a, 14b) of the at least one drive roll (14) comprising at least one wheel (16, 18, 20, 22).

11. 11. An earth-moving machine according to any one of claims 1 to 10, characterized in that a slip detection device (62) is provided for detecting a slip state of at least one, preferably of each, driven roll segment (12a, 12b, 14a, 14b).

12. 12. An earthmoving machine according to claim 11, characterized in that the slip detection device (62) comprises a speed sensor (56, 58, 60, 62) arranged on at least one, preferably on each, drive roll segment (12a, 12b, 14a, 14b).

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