Patent Application
20250207338
The present invention relates to an electro-hydraulic drive system for a ground processing machine, for example a ground compactor, with at least one drive roller.
Ground processing machines designed as ground compactors can, for example, comprise, as drive rollers, two ground processing rollers, in particular compactor rollers, arranged one after the other in a longitudinal direction of the ground compactor and rotatable about mutually parallel axes of rotation. Both ground processing rollers, each providing a drive roller, can be driven by an electro-hydraulic drive system to rotate about the respective associated axis of rotation. In association with each ground processing roller, the electro-hydraulic drive system may comprise one or two hydraulic traction motors, each fed in pairs or together with hydraulic fluid by one or more hydraulic traction pumps to generate a drive torque.
It is the object of the present invention to provide an electro-hydraulic drive system for a ground processing machine, a ground processing machine constructed with such an electro-hydraulic drive system and a method for operating such a ground processing machine, with which a high efficiency in the utilization of the electrical energy used for the drive is achieved.
According to the invention, this object is achieved by an electro-hydraulic drive system for a ground processing machine with at least one drive roller, comprising:
The present invention utilizes the knowledge that an increase in efficiency in hydraulic drive systems can be achieved if the pressure level of the hydraulic pressure is increased. In order to achieve an increase in the pressure level, the electro-hydraulic drive system constructed according to the invention is designed to deactivate or depressurize individual hydraulic traction motors that are fed with hydraulic fluid in parallel. The pressure level for the hydraulic traction motor(s) that are still fed with hydraulic fluid to generate drive torque is increased accordingly so that they can be operated with greater efficiency. The higher efficiency of the hydraulic traction motors, which are still fed with hydraulic fluid to generate a drive torque, overcompensates for flow losses in the deactivated or depressurized hydraulic traction motors.
A transition into such a state, in which only a portion of the hydraulic traction motors are fed with hydraulic fluid to generate a drive torque, can occur, for example, when working at a main operating point, for example when a ground compactor is used to compact asphalt behind an asphalt paver on a substantially horizontal surface. In this state, for example, only one of two compactor rollers that are basically used as drive roller can be driven to rotate, or only one of the two hydraulic traction motors assigned to each of the two compactor rollers can be used to generate a drive torque.
In order to supply the various hydraulic traction motors with hydraulic fluid, it is proposed that at least one hydraulic circuit is provided with at least two hydraulic traction motors fed with hydraulic fluid in parallel by at least one hydraulic traction pump, and that the valve arrangement comprises at least one switching valve unit in association with the at least two hydraulic traction motors of at least one hydraulic traction circuit.
In order to suitably condition the hydraulic traction motors for the various operating modes, when the at least one switching valve unit assigned to a hydraulic traction motor is switched to a basic drive state switching position, hydraulic fluid delivered by the at least one hydraulic traction pump can be fed to this hydraulic traction motor to generate a drive torque, and when the at least one switching valve unit assigned to a hydraulic traction motor is switched to a high-pressure drive state switching position, a bypass flow path assigned to this hydraulic traction motor and parallel to it can be open for flow- through and/or generate a flow short circuit between two fluid connections of the hydraulic traction motor.
In a particularly advantageous embodiment for switching the hydraulic traction motors between an active and an inactive state, at least two hydraulic traction circuits can be provided, each hydraulic traction circuit being assigned a hydraulic traction pump and at least two hydraulic traction motors fed with hydraulic fluid in parallel by the hydraulic traction pump.
Each hydraulic traction pump can be assigned an electric drive motor so that each hydraulic traction pump can be operated independently of other hydraulic traction pumps by its individually assigned electric drive motor.
For a simple design of the valve arrangement, this can comprise a switching valve unit in each of the hydraulic traction circuits assigned to each hydraulic traction motor, which shuts off the bypass flow path parallel to this in the basic drive state switching position and releases it for flow-through in the high-pressure drive state switching position.
In an alternative design, at least one hydraulic traction circuit can be provided in the electro-hydraulic drive system, wherein the at least one hydraulic traction circuit is assigned a hydraulic traction pump and at least two, preferably at least four hydraulic traction motors fed in parallel with hydraulic fluid by the hydraulic traction pump.
When the electro-hydraulic drive system is constructed with one or a single hydraulic traction circuit, the valve arrangement associated with each hydraulic traction motor can comprise a switching valve unit that blocks the bypass flow path parallel to it in the basic drive state switching position and releases it for flow in the high-pressure drive state switching position.
In order to achieve greater variability when activating or deactivating the hydraulic traction motors, it is proposed that the hydraulic traction motors form at least two hydraulic traction motor groups fed in parallel by the hydraulic traction pump, each with at least two hydraulic traction motors fed in parallel by the hydraulic traction pump, wherein the valve arrangement associated with each hydraulic traction motor group comprises at least one shut-off valve unit for selectively blocking this hydraulic traction motor group against the supply of hydraulic fluid delivered by the hydraulic traction pump and releasing this hydraulic traction motor group for the supply of hydraulic fluid delivered by the hydraulic traction pump.
In this case, for the defined coupling or uncoupling of individual hydraulic traction motor groups, the valve arrangement associated with each hydraulic traction motor group can comprise two shut-off valve units arranged on both sides of this hydraulic traction motor group in the direction of fluid flow.
In a further alternative embodiment, the valve arrangement can comprise two switching valve units associated with each hydraulic traction motor, wherein in the basic drive state switching position the switching valve units associated with a respective hydraulic traction motor release the supply of hydraulic fluid delivered by the hydraulic traction pump to this hydraulic traction motor and in the high-pressure drive state switching position release the bypass flow path parallel to this hydraulic traction motor to generate the flow short circuit between the fluid connections of this hydraulic traction motor.
In order to be able to switch one or more hydraulic traction motors on or off during operation, i.e. when fluid pressure is present, it is proposed that at least one, preferably every switching valve unit is designed as a proportional valve. The ability to switch on one or more hydraulic traction motors during driving is particularly advantageous if they are also to be used to generate a braking torque if necessary.
The object stated at the outset is further achieved by a ground processing machine, preferably a ground compactor, comprising at least one drive roller and an electro-hydraulic drive system constructed according to the invention.
Depending on the intended use of a particular ground processing machine, at least one, preferably each drive roller may comprise a ground processing roller. It can also be provided that at least one drive roller comprises at least one wheel, in particular a rubber wheel.
According to a further aspect, the object mentioned at the outset is achieved by a method for operating a ground processing machine according to the invention, This method may include at least one of the following measures:
In order to be able to generate a sufficient drive torque in the high-pressure drive state, the method according to the invention can further provide that in a second part of the hydraulic traction motors the respectively assigned switching valve units are switched to the basic drive state switching position.
For a defined, even load distribution, for example on two axles or two sides of the ground processing machine, it can be provided that the first part of the hydraulic traction motors comprises half of the hydraulic traction motors of the ground processing machine. The second part of the hydraulic traction motors can then, for example, comprise the other half of the hydraulic traction motors of the ground processing machine.
Furthermore, the hydraulic traction motors of the first part of hydraulic traction motors can be assigned to at least one first drive roller of the ground processing machine that can rotate about a first axis of rotation, and/or the hydraulic traction motors of the second part of hydraulic traction motors can be assigned to at least one second drive roller of the ground processing machine that can rotate about a second axis of rotation. This means that in the high-pressure operating state, all active hydraulic traction motors can act on one axle.
For load distribution across two axles, some of the hydraulic traction motors of the first part of hydraulic traction motors can be assigned to at least one first drive roller of the ground processing machine that can rotate about a first axis of rotation, and some of the hydraulic traction motors of the second part of hydraulic traction motors can be assigned to at least one first drive roller of the ground processing machine that can rotate about the first axis of rotation, or/and some of the hydraulic traction motors of the first part of hydraulic traction motors can be assigned to at least one second drive roller of the ground processing machine that can rotate about a second axis of rotation, and some of the hydraulic traction motors of the second part of hydraulic traction motors can be assigned to at least one second drive roller of the ground processing machine that can rotate about the second axis of rotation.
The present invention is described in detail below with reference to the attached figures. In particular:
In
The two drive rollers 12, 14 can, as illustrated in
It is also to be noted that different embodiments of such ground processing machines can be used in the context of an electro-hydraulic drive system described in the following. 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, can be provided on a rear carriage, while a ground processing roller 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.
In
The hydraulic traction circuit K1 is also assigned a hydraulic traction pump P1, which can be driven by an individually assigned electric drive motor E1 for pumping fluid through the hydraulic traction circuit K1 and the hydraulic traction motors M1, M2 arranged parallel to one another in the latter. Likewise, a hydraulic traction pump P2 is assigned to the hydraulic traction circuit K2. The hydraulic traction pump P2 is driven by an electric drive motor E2 assigned to it for pumping fluid through the hydraulic traction circuit K2 and the hydraulic traction motors M3, M4 which are connected in parallel to one another and thus through which hydraulic fluid can flow.
A bypass flow path B1, B2, B3, B4 connected in parallel to each of the hydraulic traction motors M1, M2, M3, M4 is provided. A valve arrangement of the electro-hydraulic drive system, generally designated 26, comprises, in association with each of the four hydraulic traction motors M1, M2, M3, M4, a switching valve unit S1, S2, S3, S4 arranged in the respectively associated bypass flow path B1, B2, B3, B4.
Just like the two electric drive motors E1, E2, the switching valve units S1, S2, S3, S4 are controlled by a control unit generally designated 28. By means of the control unit 28, the switching valve units S1, S2, S3, S4 can be switched between a basic drive state switching position and a high-pressure drive state switching position. In the basic drive state switching position shown in association with each of the switching valve units S1, S2, S3, S4, the respectively associated bypass flow path B1, B2, B3, B4 is blocked off against the flow of hydraulic fluid, so that the hydraulic fluid conveyed by means of the respective hydraulic traction pump P1 or P2 through the respective hydraulic traction circuit K1, K2 flows through both hydraulic traction motors M1, M2, M3, M4 and therefore preferably the same drive torque is generated by all four hydraulic traction motors M1, M2, M3, M4.
In a high-pressure drive state switching position of the switching valve units S1, S2, S3, S4, the respectively assigned bypass flow path B1, B2, B3, B4 is released for the flow of hydraulic fluid, so that, provided the respectively assigned hydraulic traction pump P1, P2 is still operating, the hydraulic fluid delivered by the respective hydraulic traction pump P1, P2 is conveyed past the respectively assigned hydraulic traction motor M1, M2, M3, M4 due to the lower flow resistance and no drive torque is generated in a hydraulic traction motor M1, M2, M3, M4, whose assigned switching valve unit S1, S2, S3, S4 is set to the high-pressure operating state switching position. becomes. In principle, in the high-pressure drive state of the electro-hydraulic drive system 24 or when the switching valve units S1, S2 or S3, S4 are switched to the high-pressure drive state, the operation of the associated hydraulic traction pump P1 or P2 is not necessary. When the hydraulic traction pump P1 or P2 is deactivated, the hydraulic traction motors M1, M2 or M3, M4, driven by the respectively assigned drive roller rolling on the ground, circulate fluid between their fluid connections 30, 32 which are short-circuited via the respectively assigned bypass flow path B1, B2 or B3, B4.
It should be noted that the switching valve units S1, S2, S3, S4 can be designed, for example, as proportional valves, so that they can be switched between their two switching positions even during driving without switching shocks occurring. In a simpler design, these switching valve units S1, S2, S3, S4 can be designed as continuous valves or binary-acting valves that can only be switched between an open state and a closed state. In order to avoid switching shocks, it is advantageous to switch such valves between the two switching positions when they are at a standstill, i.e. without pressure.
In normal operation of the ground processing machine 10, designed for example as a ground compactor, or of the electro-hydraulic drive system 24 shown in
If, for example, when the ground processing machine 10 is in a transfer journey between two construction sites, switching to the high-pressure drive state is required, the hydraulic traction motors M3, M4 assigned to the drive roller 14 can be deactivated. For this purpose, the switching valve units S3, S4 assigned to them are set to their high-pressure drive state switching position, in which they release the respectively assigned bypass flow path B3, B4 for flow-through. At the same time, the hydraulic traction pump P2 can be deactivated so that no fluid is pumped through the fluid circuit K2. The hydraulic traction motors M3, M4 are short-circuited via the open bypass flow paths assigned to them, so that they can rotate with the rolling drive roller 14 and can circulate fluid via the bypass flow path B3 or B4, which creates a flow short circuit. Alternatively, in this state it is also possible to continue operating the hydraulic traction pump P2 in order to prevent blocking of the hydraulic traction motors M3, M4 and the resulting possible dragging of the drive roller 14 over the ground.
In this high-pressure drive state of the electro-hydraulic drive system 24, the entire drive torque is then generated by the hydraulic traction motors M1, M2 of the hydraulic traction circuit K1 fed by the hydraulic traction pump P1. The higher fluid pressure required for this in the hydraulic traction circuit K1 is generated by a correspondingly higher drive power of the electric drive motor E1. Due to the fact that in this state the hydraulic traction circuit K1 operates with a fluid pressure which is essentially twice the fluid pressure in the basic drive state, the hydraulic traction motors M1, M2 are operated with significantly higher efficiency, which more than compensates for the energy losses generated by the circulation of fluid by the dragged hydraulic traction motors M3, M4.
In order to be able to generate a sufficient braking torque when driving downhill, for example, the hydraulic traction circuit K2 of the initially non-driven drive roller 14 can be reactivated when changing to a braking state from the high-pressure drive state. For this purpose, the switching valve units S3, S4 are switched to their basic drive state switching position, so that in the braking state a braking torque is generated by the hydraulic traction motors M3, M4 driven by the drive roller 14 or the hydraulic traction pump P1, which can also be used, for example, to feed electrical energy back via the electric drive motor E2 which is then operated as a generator.
In the electro-hydraulic drive system 24 shown in
In the ground processing machine 10 shown in
An alternative embodiment of an electro-hydraulic drive system 24 is shown in
In association with each of the hydraulic traction motors M1, M2 or M3, M4, a parallel bypass flow path B1, B2, B3, B4 is provided, each with a switching valve unit S1, S2, S3, S4 provided therein. Here too, in conjunction with the hydraulic traction motors M1, M2 or M3, M4 provided in pairs in a group G1, G2, only one jointly used bypass flow path with a single switching valve unit could be provided.
The valve arrangement 26 further comprises two shut-off valve units V1, V2 and V3, V4, respectively, associated with each of the two groups G1, G2. The shut-off valve units V1, V2, V3, V4, which are also designed as proportional valves, for example, are arranged in the flow direction on both sides of the respectively assigned pair of hydraulic traction motors M1, M2 or M3, M4 and, like the switching valve units S1, S2, S3, S4, are controlled by the control unit 28 shown in
In the basic drive state, the shut-off valve units V1, V2, V3, V4 are in the basic drive state switching position shown in
If the high-pressure drive state is to be switched to and, for example, the hydraulic traction motors M1, M2 of group G1 are to be used to generate the drive torque, the shut-off valve units V1, V2 and switching valve units S1, S2 assigned to them remain in the basic drive state switching position. The shut-off valve units V3, V4 and switching valve units S3, S4 assigned to the hydraulic traction motors M3, M4 of group G2 are switched to the high-pressure drive state switching position, in which on the one hand the supply of fluid to the hydraulic traction motors M3, M4 is prevented by the shut-off valve units V3, V4 and on the other hand the bypass flow paths B3, B4 are released for flow through by the switching valve units S3, S4 provided therein. The hydraulic traction motors M3, M4 are then dragged along by the drive roller assigned to them and can circulate fluid via the respectively assigned bypass flow path B3, B4.
In this type of design of an electro-hydraulic drive system 24, too, by selecting the assignment of the various hydraulic traction motors M1, M2, M3, M4 to the two groups G1, G2 in the high-pressure drive state, the drive torque can be transmitted either to a drive roller or two segments of a drive roller that can rotate about the same axis of rotation, while no drive torque is generated on the other axis, or a part of the drive torque can be generated on each of the two axes, for example on segmented drive rollers or intrinsically rigid drive rollers.
Another alternative embodiment of an electro-hydraulic drive system 24 is shown in
The valve arrangement 26 comprises, in association with each hydraulic traction motor M1, M2, M3, M4 or in association with each bypass flow path B1, B2, B3, B4, two switching valve units S11, S12, S21, S22, S31, S32, S41, S42 positioned in the flow direction on both sides of the respectively associated hydraulic traction motor M1, M2, M3, M4. In the basic drive state switching position of the switching valve units S11, S12, S21, S22, S31, S32, S41, S42 shown in
When transitioning to the high-pressure drive state, the associated pair of switching valve units S11, S12 or S21, S22 or S31, S32 or S41, S42 of at least one of the hydraulic traction motors M1, M2, M3, M4 can be brought into the high-pressure drive state switching position, in which the fluid connections 30, 32 of the associated hydraulic traction motor M1, M2, M3, M4 are decoupled from the hydraulic traction pump P1 or from the hydraulic traction circuit K1 and are connected to the associated bypass flow path B1, B2, B3, B4. Each hydraulic traction motor M1, M2, M3, M4 not used to generate a drive torque in the high-pressure drive state can then circulate fluid via the associated bypass flow path B1, B2, B3, B4.
In the type of embodiment shown in
In order to be able in this embodiment to switch between the different drive states during the forward movement of the ground processing machine 10 and to enable the switching on of hydraulic traction motors to generate a braking torque when the ground processing machine 10 is operated in the high-pressure drive state, the switching valve units S11, S12, S21, S22, S31, S32, S41, S42 can be designed as proportional valves which enable a gradual transition when switching between the different switching states, avoiding switching shocks.
It should also be noted that the present invention can also be applied to an electro-hydraulic drive system for a ground processing machine with only two hydraulic traction motors, for example each associated with two undivided ground processing rollers. In the high-pressure drive state, only one of the two hydraulic traction motors can be fed with fluid at a correspondingly increased pressure, while no fluid is fed to the other hydraulic traction motor.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE102023135899.5 | Dec 2023 | DE | national |
