Patent Application
20250207337
The present invention relates to a ground processing machine having two drive rollers arranged one after the other in a machine longitudinal direction and rotatable about a respective axis of rotation, wherein each drive roller comprises two drive roller segments arranged one after the other in the direction of the associated axis of rotation, and having a hydraulic drive system for the drive rollers.
To ensure that torque can continue to be transmitted via other drive roller segments in ground processing machines such as those designed as ground compactors when slippage occurs in one or more of the drive roller segments, it is known to use flow dividers which, when excessive fluid outflow occurs via the hydraulic drive motor associated with such a drive roller segment in a slipping state of a drive roller segment, block or throttle the fluid supply to this drive roller segment and thus maintain a sufficient supply of fluid to the non-slipping drive rollers.
It is the object of the present invention to provide a ground processing machine in which the occurrence of slippage conditions of one or more drive roller segments can be avoided with a structurally simple design of a hydraulic drive system that efficiently uses the energy applied.
According to the invention, this object is achieved by a ground processing machine having two drive rollers arranged one after the other in a machine longitudinal direction and rotatable about a respective axis of rotation, wherein each drive roller comprises two drive roller segments arranged one after the other in the direction of the associated axis of rotation, and having a hydraulic drive system for the drive rollers, wherein the hydraulic drive system comprises:
wherein:
In the ground processing machine constructed according to the invention, regardless of the fluid flow direction and thus also regardless of the direction of rotation in which the traction drive hydraulic motors operate, the traction drive hydraulic motors associated with the various drive roller segments are connected crosswise on the outflow side to the two traction drive hydraulic pumps. This means that two traction drive hydraulic motors connected on the inflow side to one of the two traction drive hydraulic pumps are not both connected to this traction drive hydraulic pump on the outflow side. One of the two traction drive hydraulic motors connected to the same traction drive hydraulic pump on the inflow side is connected on the outflow side together with another one of the traction drive hydraulic motors to the other traction drive hydraulic pump.
The result of this is that, if slippage occurs in one of the drive roller segments, a larger amount of fluid is prevented from flowing out via the drive hydraulic motor associated with this drive roller segment by the fact that the drive hydraulic pump connected to the outflow side of this traction drive hydraulic motor only takes up a quantity of fluid defined by its rotational speed, even in the slip state, and therefore the amount of fluid flowing out via the traction drive hydraulic motor of a slipping drive roller segment is substantially limited by the amount of fluid delivered by the traction drive hydraulic motor connected to the same drive hydraulic pump on the outflow side together with this traction drive hydraulic motor.
Excessive outflow of fluid via a traction drive hydraulic motor associated with a slipping drive roller segment is prevented due to this cross-outflow connection of the traction drive hydraulic motors with the traction drive hydraulic pumps without the need to provide a flow divider. This leads to a structurally significantly simpler design of the hydraulic drive system and, due to the fact that flow dividers generally lead to energy losses, a more efficient use of the energy provided to drive the traction drive hydraulic pumps. This is particularly advantageous in electro-hydraulic drive systems in which the traction drive hydraulic pumps are driven by at least one electric drive motor and the amount of electrical energy that can be stored in energy storage units and thus also the range or operating time of a ground processing machine is limited.
If the hydraulic drive system has a simple design, ensuring that both traction drive hydraulic pumps deliver substantially the same amount of fluid to be able to achieve the same rotational speeds on all traction drive hydraulic motors, both traction drive hydraulic pumps can be driven by a common drive motor for delivering hydraulic fluid, or/and both traction drive hydraulic pumps can have the same delivery volume. Furthermore, all traction drive hydraulic motors can have the same displacement volume. The delivery volume of a traction drive hydraulic pump can, for example, be the volume of fluid delivered per revolution of the traction drive hydraulic pump, and the displacement volume of a traction drive hydraulic motor can be the volume of fluid absorbed per revolution of the traction drive hydraulic motor.
To operate a ground processing machine electro-hydraulically, at least one drive motor can be an electric motor.
In particular in electro-hydraulic drive systems, that is, when one or more drive motors are designed as electric motors, it is advantageous to obtain a simply structured hydraulic drive system that each traction drive hydraulic pump is a pump with a fixed delivery volume or/and that each traction drive hydraulic motor is a motor with a fixed displacement volume. This means that, during operation, the traction drive hydraulic pumps or the traction drive hydraulic motors do not have to be adjusted to achieve different rotational speeds and thus also different travel speeds of the ground processing machine. This can be achieved simply by changing the rotational speed of the drive motor(s).
An extended networking of the traction drive hydraulic motors for further improved slip control can be achieved in that:
and
This makes it possible to change the pairings of the traction drive hydraulic motors connected to the same traction drive hydraulic pump on the outflow side depending on the drive roller segment at which slip occurs.
To be able to change the cross-connection of the traction drive hydraulic motors with the traction drive hydraulic pumps in a defined manner depending on the drive roller segments at which slip occurs, a control arrangement for controlling the first valve unit, the second valve unit, the third valve unit and the fourth valve unit can be provided, which is designed to:
and
To be able to compensate for fluid leaks, for example in the area of the traction drive hydraulic motors, a fluid feed arrangement can be provided for feeding fluid into at least one fluid line of the first fluid line, second fluid line, third fluid line, and fourth fluid line.
Such a fluid feed arrangement is generally designed to feed fluid on the low-pressure side of a hydraulic circuit, that is, into the hydraulic lines connecting the traction drive hydraulic motors on the outflow side to the traction drive hydraulic pumps, to keep the fluid pressure in the area of these lines at a defined level. In interaction with such a fluid feed arrangement, if slippage occurs on a drive roller segment, the associated traction drive hydraulic motor can briefly operate at a slightly increased rotational speed and thus also with a correspondingly greater fluid outflow. The greater fluid outflow via such a traction drive hydraulic motor can in principle be compensated by a smaller feed of fluid through the fluid feed arrangement, even if the limitation is basically defined by the amount of fluid fed back to the same traction drive hydraulic pump from another traction drive hydraulic motor. Due to this interaction, a reduced drive torque is set at a traction drive hydraulic motor associated with a drive roller segment with traction loss, which corresponds to the maximum drive torque that can be transmitted via this drive roller segment without slip.
A first drive roller of the two drive rollers may comprise the first drive roller segment and the second drive roller segment, and a second drive roller of the two drive rollers may comprise the third drive roller segment and the fourth drive roller segment.
To reduce the probability of a state occurring in which two traction drive hydraulic motors that fundamentally limit each other in terms of the fluid outflow quantity simultaneously enter a slip state by a defined association of the cross-connected traction drive hydraulic motors with the various drive roller segments, it is proposed that, with respect to a machine longitudinal direction, the first drive roller segment and the third drive roller segment are arranged on a first side of the ground processing machine and the second drive roller segment and the fourth drive roller segment are arranged on a second side of the ground processing machine. This association of the traction drive hydraulic motors with the drive roller segments also makes it possible for different rotational speeds to occur on the drive roller segments on the inside and outside of the curve when cornering, without the traction drive hydraulic motors connected to one another on the outflow side blocking one another with the fluid quantities they each deliver.
When a ground processing machine is designed as a ground compactor, at least one drive roller of the two drive rollers can be a ground processing roller, wherein each drive roller segment of the at least one drive roller is provided by a roller segment. Alternatively or additionally, at least one drive roller of the two drive rollers may comprise at least two wheels, wherein each drive roller segment of the at least one drive roller comprises at least one wheel. Such drive wheels can be drive wheels that purely serve to drive the ground processing machine, for example, positioned on both sides of a rear carriage, or can also be, for example, rubber wheels of a rubber-wheeled roller associated with one another in pairs.
To be able to take suitable measures when slip occurs, for example by the defined switching of various valve units, a slip detection arrangement for detecting a slip state of at least one drive roller segment, preferably of each drive roller segment, can be provided.
The slip detection arrangement can comprise a rotational speed sensor in association with at least one drive roller segment, preferably with each drive roller segment.
The present invention is described in detail below with reference to the attached figures. Wherein:
The two drive rollers 12, 14 are designed as split ground processing rollers with respective drive roller segments 12a, 12b and 14a, 14b. Each of the drive roller segments 12a, 12b, 14a, 14b is associated with one of the four traction drive hydraulic motors M1, M2, M3, M4, so that the two drive roller segments 12a, 12b can be driven independently of one another by the traction drive hydraulic motors M1, M2 associated with them to rotate about the axis of rotation D1, and the two drive roller segments 14a, 14b can be driven independently of one another by the traction drive hydraulic motors M3, M4 associated with them to rotate about the axis of rotation D2.
It should also be noted that other embodiments of such ground processing machines can be applied in the context of a hydraulic drive system described hereinafter. For example, in the case of a ground processing machine designed as a ground compactor, a pair of drive wheels, each forming a drive roller segment of a drive roller, can be provided on a rear carriage, while a ground processing roller divided into roller segments can act as a drive roller on the front carriage. The principles of the present invention can be applied to pivot-steered ground processing machines or ground compactors as well as to ground processing machines divided into front and rear carriages.
The hydraulic drive system 24 comprises two traction drive hydraulic pumps P1, P2 and the four traction drive hydraulic motors M1, M2, M3, M4 in a hydraulic circuit 26. The two traction drive hydraulic pumps P1, P2 can be driven jointly by a drive motor E designed as an electric motor.
A first fluid connection 28 of the first traction drive hydraulic pump P1 is connected via a first hydraulic line L1 to a first fluid connection 30 of the first traction drive hydraulic motor M1 and a first fluid connection 32 of the second traction drive hydraulic motor M2. A first fluid connection 34 of the second traction drive hydraulic pump P2 is connected via a second hydraulic line L2 to a first fluid connection 36 of the third traction drive hydraulic motor M3 and a first fluid connection 38 of the fourth traction drive hydraulic motor M4.
A second fluid connection 40 of the first traction drive hydraulic pump P1 is connected via a third fluid line L3 to a second fluid connection 42 of the second traction drive hydraulic motor M2 and a second fluid connection 44 of the third traction drive hydraulic motor M3. A second fluid connection 46 of the second traction drive hydraulic pump P2 is connected via a fourth fluid line L4 to a second fluid connection 48 of the first traction drive hydraulic motor M1 and a second fluid connection 50 of the fourth traction drive hydraulic motor M4.
Depending on the direction in which the ground processing machine 10 is to be moved, for example when driving forward, the drive motor E can be controlled by a control unit 52 for operating the traction drive hydraulic pumps P1, P2 in such a conveying direction that they feed fluid at their respective first fluid connections 28, 34 into the first hydraulic line L1 or the second hydraulic line L2 and therefore feed the fluid under high pressure, for example hydraulic oil, via the respective first fluid connections 30, 32, 36, 38 into the traction drive hydraulic motors M1, M2, M3, M4.
In this state, the traction drive hydraulic motors M1, M2, M3, M4 release the fluid under significantly reduced pressure at their respective second fluid connections 48, 42, 44, 50 into the third hydraulic line L3 or the fourth hydraulic line L4, via which the fluid flows back to the second fluid connections 40, 46 of the traction drive hydraulic pumps P1, P2.
If the ground processing machine 10 is to be moved in the opposite direction, for example in reverse, the drive motor E is controlled such that the traction drive hydraulic pumps P1, P2 driven by it release the fluid via their respective second fluid connections 40, 46 into the third hydraulic line L3 or the fourth hydraulic line L4. The fluid delivered by the first traction drive hydraulic pump P1 flows via the third hydraulic line L3 to the second fluid connections 42, 44 of the second traction drive hydraulic motor M2 and the third traction drive hydraulic motor M3. The fluid delivered by the second traction drive hydraulic pump P2 flows via the fourth hydraulic line L4 to the second fluid connections 48, 50 of the first traction drive hydraulic motor M1 and the fourth traction drive hydraulic motor M4, respectively. In this operating state, the first traction drive hydraulic motor M1 and the second traction drive hydraulic motor M2 deliver fluid at their first fluid connections 30, 32 via the first hydraulic line L1 to the first fluid connection 28 of the first traction drive hydraulic pump 28, and the third traction drive hydraulic motor M3 and the fourth traction drive hydraulic motor M4 deliver fluid at their first fluid connections 36, 38 via the second fluid line L2 to the first fluid connection 34 of the second traction drive hydraulic pump P2.
By means of a feed arrangement generally designated 53, fluid leaks occurring in particular in the area of the traction drive hydraulic motors M1, M2, M3, M4 can be compensated by feeding fluid onto the low-pressure side of the hydraulic circuit 26. For this purpose, the feed arrangement 54 comprises a feed pump S, which is driven, for example, by a drive motor associated therewith, which pump draws fluid from a fluid reservoir F and feeds it via four feed valves E1, E2, E3, E4 into the first hydraulic line L1, the second hydraulic line L2, the third hydraulic line L3, and the fourth hydraulic line L4, respectively.
In the hydraulic drive system 24 shown in
However, on the low-pressure side, that is, the outflow side, the traction drive hydraulic motors that are also connected to one of the traction drive hydraulic pumps on the high-pressure side are not also connected to the same traction drive hydraulic pump. Only one of the traction drive hydraulic motors connected to a traction drive hydraulic pump on the high-pressure side is also connected to this traction drive hydraulic pump on the low-pressure side, while the other traction drive hydraulic motor is connected to the other traction drive hydraulic pump on the low-pressure side. In the illustrated embodiment, this means that, when fluid is delivered via the first fluid connections 28, 34 of the traction drive hydraulic pumps P1, P2, the second traction drive hydraulic motor M2 and the third traction drive hydraulic motor M3 are connected to the first traction drive hydraulic pump P1 via the third hydraulic line M3, while the first traction drive hydraulic motor M1 and the fourth traction drive hydraulic motor M4 are connected to the second traction drive hydraulic pump P2 via the fourth hydraulic line M4.
When moving in the opposite direction, that is, when fluid is released via the respective second fluid connections 40, 46 of the traction drive hydraulic pump P1, P2, the second traction drive hydraulic motor M2 and the third traction drive hydraulic motor M3 are connected to the first traction drive hydraulic pump 28 on the high-pressure side, that is, via the third hydraulic line L3, while the first traction drive hydraulic motor M1 and the fourth traction drive hydraulic motor M4 are connected to the second traction drive hydraulic pump P2 via the fourth hydraulic line L4. In this state, on the low-pressure side, the first traction drive hydraulic motor M1 and the second traction drive hydraulic motor M2 are connected to the first traction drive hydraulic pump P1 via the first hydraulic line L1, while the third traction drive hydraulic motor M3 and the fourth traction drive hydraulic motor M4 are connected to the second traction drive hydraulic pump P2 via the second hydraulic line L2.
Since in such a hydraulic drive system 24 each of the traction drive hydraulic pumps P1, P2 can only take in as much fluid on the low-pressure side as it delivers on the high-pressure side during delivery operation, it is important that in this cross-connection of the traction drive hydraulic motors M1, M2, M3, M4 with the traction drive hydraulic pumps P1, P2, each of the traction drive hydraulic pumps P1, P2 delivers substantially the same amount of fluid and each of the traction drive hydraulic motors M1, M2, M3, M4 takes in substantially the same amount of fluid. In particular, when designed as an electro-hydraulic drive system, it is advantageous if the traction drive hydraulic pumps P1, P2 have a constant delivery volume and the traction drive hydraulic motors M1, M2, M3, M4 have a constant displacement volume. Changes in the delivery rate can be generated solely by changing the rotational speed of the drive motor E, which is designed as an electric motor. With such a design of the traction drive hydraulic pumps P1, P2 and traction drive hydraulic motors M1, M2, M3, M4, each having the same delivery volume or displacement volume, all traction drive hydraulic motors M1, M2, M3, M4 rotate at the same rotational speed or drive the drive roller segments 12a, 12b, 14a, 14b associated with them to rotate at the same rotational speed. This in turn requires that all drive roller segments 12a, 12b, 14a, 14b have the same diameter. If the drive rollers 12, 14 provided in association with the various axes of rotation D1, D2 have different diameters, traction drive hydraulic motors with different displacement volumes can be used for the drive roller segments 12a, 12b on the one hand and the drive roller segments 14a, 14b on the other hand in the association of the traction drive hydraulic motors M1, M2, M3, M4 with the drive roller segments 12a, 12b, 14a, 14b, as shown in particular in
The cross-connection of the traction drive hydraulic motors M1, M2, M3, M4 ensures that none of the drive roller segments 12a, 12b, 14a, 14b can enter a slip state in which an excessively large amount of fluid flows out of the associated traction drive hydraulic motor due to an increase in rotational speed of the motor. If, for example, slippage were to occur on the first drive roller segment 12a due to a loss of traction, this would result in the drive hydraulic motor M1 taking in and accordingly releasing a larger quantity of fluid due to a correspondingly higher rotational speed. Since the first traction drive hydraulic motor M1, in a state in which it receives fluid from the first traction drive hydraulic pump P1 via the first hydraulic line L1, for example, releases the absorbed fluid into the fourth fluid line L4, and since the fourth traction drive hydraulic motor M4 fed by the other traction drive hydraulic pump P2 releases the amount of fluid corresponding to normal traction into the fourth hydraulic line L4 in this state, the fourth hydraulic line La can only absorb the amount of fluid that it would basically also release in a slip-free state from the first traction drive hydraulic motor M1. The first traction drive hydraulic motor M1 could therefore in principle not rotate faster than the other traction drive hydraulic motors M2, M3, M4, even in the event of a loss of traction of the associated first drive roller segment 12a, and therefore also not lead to an excessive outflow of fluid from the first hydraulic line L1.
However, due to the fluid leaks mentioned above, there is basically the possibility that the first drive hydraulic motor M1 briefly releases a larger amount of fluid when a loss of traction occurs at the associated first drive roller segment 12a than would be the case in the non-slipping state. This larger amount of fluid fed into the fourth hydraulic line L4 via the first traction drive hydraulic motor M1 then does not have to be replenished by the feed arrangement 53 to maintain the defined pressure on the low-pressure side of the hydraulic circuit 26.
Such a short-term slip-related increase in rotational speed of the first drive hydraulic motor M1 leads to a spontaneous drop in pressure on the high-pressure side, in this case in the first hydraulic line L1. This pressure drop results in a decrease of the drive torque generated at the first drive hydraulic motor to such a value that the first drive roller segment 12a, which has lower traction, is again operated without slip. This decrease in the drive torque at the first traction drive hydraulic motor M1 also leads to a corresponding decrease in the drive torque of the second traction drive hydraulic motor M2, which is subjected to the same pressure. Since the drive power of the drive motor E is basically maintained, a correspondingly higher pressure is created in the second hydraulic line L2 fed from the second drive hydraulic pump P2, so that the drive hydraulic motors M3, M4 fed from the second hydraulic line L2 are operated at a correspondingly increased drive torque.
The previously described independent adjustment of the drive torque or the rotational speed of a drive roller segment when a loss of traction occurs is independent of which of the drive roller segments the loss of traction occurs on and in which direction the ground processing machine 10 is moved. Due to the connection on the outflow side of each traction drive hydraulic motor M1, M2, M3, M4 with another traction drive hydraulic motor which is not fed from the same traction drive hydraulic pump, the traction drive hydraulic motors block each other against a slip-related increase in rotational speed.
Despite this mutual blocking of the drive hydraulic motors M1, M2, M3, M4 which are linked to one another on the outflow side, there is the possibility, particularly in the case of association of the drive hydraulic motors M1, M2, M3, M4 to the drive roller segments 12a, 12b, 14a, 14b as shown in
The valve units V1, V2 controlled by the control unit 52 are basically controlled in such a way that when one of the valve units V1, V2 establishes a connection of the second fluid connection 48 of the first traction drive hydraulic motor M1, the other valve unit interrupts the connection with the associated hydraulic line. The second fluid connection 48 of the first traction drive hydraulic motor M1 is therefore either in connection with the third fluid line L3 or in connection with the fourth fluid line L4.
The third valve unit V3 associated with the second traction drive hydraulic motor M2 optionally establishes a connection of the second fluid connection 42 with the third hydraulic line L3 or interrupts it. Likewise, the fourth valve unit V4 optionally establishes a connection between the second fluid connection 42 of the second traction drive hydraulic motor M2 and the fourth fluid line M4 or interrupts it. The two valve units V3, V4 are also controlled by the control unit 52 in such a way that when one of the valve units establishes the connection with the associated hydraulic line, the other valve unit is in its interrupted state.
Furthermore, the four valve units V1, V2, V3, V4 are controlled or operated by the control unit 52 such that a state in which the two second outlet connections 48, 42 of the traction drive hydraulic motors M1, M2 are in connection with the same hydraulic line L3 or L4 does not occur. When the second fluid connection 48 of the first traction drive hydraulic motor M3, as shown in
The switching state of the valve units V1, V2, V3, V4 shown in
If, in such a state, a loss of traction were to occur at the two drive roller segments 12a, 14a or 12b, 14b positioned on the same side of the ground compactor 10 with respect to the machine longitudinal direction R, that is, on the same side in the machine transverse direction Q, a fluid short circuit can occur in the hydraulic circuit 26, in which the entire fluid delivered by the traction drive hydraulic pumps P1, P2 flows away via the traction drive hydraulic motors associated with the slipping drive roller segments, while no fluid flows via the traction drive hydraulic motors associated with the non-slipping drive roller segments.
To counteract this problem, in the hydraulic drive system 26 shown in
If, for example, a loss of traction with corresponding slip occurs simultaneously at the drive roller segments 12b, 14b, which in the switching state shown in
It should be noted that, in an alternative embodiment, the variability introduced by the valve units V1, V2, V3, V4 could also be achieved if these were provided in conjunction with the traction drive motors M3, Ma and the hydraulic lines L3, L4 or if these were provided in conjunction with the traction drive hydraulic motors M2 and M3 or in conjunction with the traction drive hydraulic motors M1, M4, each in association with the first hydraulic line L1 and the second hydraulic line L2.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE102023135900.2 | Dec 2023 | DE | national |
