Method for operating a construction machine and construction machine

Abstract

A method for operating a construction machine (1) for conveying viscous material, the construction machine (1) comprising a hydraulic pump (7, 10) driven by an electric motor (5) supplying a hydraulic drive (8) in driving connection with a viscous material pump unit (9), the electric motor (5) being operated by an electric control device (6) connectable to a supply network (2) via a power supply connection (2). The method comprises the step of operating the electric motor (5) by the control device (6) such that the incoming power received at the power supply connection (2) does not exceed a maximum power.

Description

[Technical Field]

[0001] The present invention relates to a method of operating a construction machine for delivering viscous material and to such a construction machine. [Background technology]

[0002] Electric construction machines for pumping viscous materials typically have a power connection for connecting to an electrical grid. This power connection is usually protected by an electrical fuse. If a power overload occurs at this power connection, the aforementioned electrical fuse may trip, which may at least temporarily interrupt the operation of the electric construction machine. Such an overload may result from a blockage in the delivery line for transporting the pumped viscous material. An overload may also result from an increase in the geodesic pump head that the construction machine must overcome when pumping the viscous material. Furthermore, an overload may be caused by the displacement of the delivery boom of the construction machine. The acquisition of additional electrical energy for the operation of at least one other power-consuming device connected to the grid may also increase the likelihood of an overload. Summary of the Invention

[0003] The object of the present invention is to provide a method for operating a construction machine for delivering viscous materials and such a construction machine, which have improved characteristics. In particular, the maximum available power should be utilized as fully as possible, allowing for highly reliable and uninterrupted operation of the construction machine. In other words, in particular, the greatest possible output power should be achieved with limited input power.

[0004] This problem is solved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims.

[0005] The method according to the present invention is used for operating a construction machine. The construction machine is used to pump viscous materials. The construction machine can be a mobile construction machine, in particular a towed construction machine or a self-propelled construction machine. In this case, the construction machine has a power connection to which a power supply network can be connected or is connected depending on the intended purpose. The supply network provides maximum power at the power connection. The construction machine includes an electric motor and an electrical control device, e.g., in the form of a frequency converter, for operating the electric motor, which receives power from the power supply network. The construction machine further includes a hydraulic pump driven by the electric motor and supplying at least one hydraulic circuit of the construction machine. In this case, power is supplied from the hydraulic circuit to at least one hydraulic drive of the construction machine. In this case, the control device operates the electric motor in such a way that the incoming power received at the power connection does not exceed the maximum available power. The method advantageously allows the maximum available power to be utilized very well, in particular at least almost completely. If the output torque provided by the hydraulic drive increases, an overload of the power supply connection may occur without controlling the electric motor according to the method. By using the method, it is possible to ensure that the maximum power is not exceeded even when the output torque fluctuates, thereby avoiding, in particular, the tripping of an electrical fuse in the power supply connection. That is, the method allows for very good utilization of the maximum power. In particular, cooperation between hydraulic and electrical components of the construction machine according to the method allows for very good utilization of the maximum power. The supply network is preferably an AC voltage network. An AC voltage network providing the maximum power may be present at the construction site. The maximum power may be limited by the power supply connection to, for example, a power value of 22 kW. Alternatively, the supply network may be a DC network, preferably a truck's vehicle electrical system.

[0006] In this context, a viscous material can be understood as a thick mixture of various substances. Viscous materials are, for example, mortar, cement, screed or concrete, respectively, in a mixable and / or dispenseable state. In a mixable and / or dispenseable state, the viscous material has not yet hardened. In particular, the viscous material is a construction material.

[0007] In an embodiment of the present invention, the torque generated by the electric motor is adjusted to limit the received power to the maximum power so that the received power corresponds to the maximum power, and therefore the maximum power can be fully utilized by the received power.

[0008] In another embodiment of the present invention, the hydraulic pump is a variable displacement pump with an adjustable swivel angle, and the variable displacement pump has an operating speed. The operating speed can correspond to the speed of the variable displacement pump at which the variable displacement pump has a sufficiently high efficiency, in particular, an optimal efficiency. In this case, to limit the received power to the maximum power, the torque generated by the electric motor is reduced so that the received power corresponds to the maximum power. As a result of the reduction in the torque generated by the electric motor, the electric motor's speed may temporarily drop. Therefore, to limit the received power to the maximum power, the swivel angle is correspondingly adjusted, and the variable displacement pump's speed is increased, thereby reducing the variable displacement pump's discharge volume, so that the power received by the variable displacement pump remains constant, precisely until the variable displacement pump's operating speed is reached again. This makes it possible to operate the variable displacement pump at the operating speed even if the output torque temporarily increases. The same applies to the electric motor. Therefore, the variable displacement pump's speed can recover at a constant received power until the variable displacement pump's operating speed is reached again. Expediently, the variable displacement pump is drivingly connected to a drive shaft of the construction machine, and other power consumers of the construction machine, in particular in the form of constant flow pumps, are drivingly connected to the same drive shaft, in particular directly or via a transmission. Therefore, what has been said above with respect to the operating speed of the variable displacement pump can also be applied, mutatis mutandis, to such other power consumers. For example, several, in particular three, variable displacement pumps and several, in particular four, other power consumers, in particular in the form of constant flow pumps, can be drivingly connected to the drive shaft, so that the aforementioned, preferably controlled, adjustment of the speed of the electric motor can advantageously also be used to adjust the volume flow delivered by the other power consumers.

[0009] The method advantageously reduces the displacement of the variable displacement pump, and thus the delivery rate of the viscous material pump unit of the construction machine, thereby allowing the variable displacement pump's speed to recover. In this case, the variable displacement pump's speed can recover from a previous drop, for example, at constant electric motor power. The drop in speed may be due to an increase in pressure that the variable displacement pump must overcome. The drop in speed may be due to a change in the power available for driving the variable displacement pump. Such a change in the power available for driving the variable displacement pump may result from turning on additional power consumers that, like the construction machine, obtain electrical energy from the supply grid, particularly via the same power connection. Power peaks in such additional power consumers connected to the supply grid may also lead to a drop in the speed of the variable displacement pump. In this way, the pump speed or the volumetric flow rate delivered by the variable displacement pump can be dynamically reduced if too little power is available from the grid.

[0010] In another embodiment of the invention, the rotational speed of the hydraulic pump and the rotational speed of the electric motor depend on each other, in particular without a gear ratio or via a gear ratio, in which case "without a gear ratio" is synonymous with "direct transmission".

[0011] In another embodiment of the invention, a method compares the incoming power with the maximum power, detects an imminent overload of the power supply connection, and controls the electric motor to prevent the overload by preventing the incoming power at the power supply connection from exceeding the maximum power. To prevent the overload, the torque generated by the electric motor can be reduced, thereby reducing the rotational speed of the hydraulic pump and, for the time being, the rotational speed of the hydraulic drive. As a result, the torque loading the variable displacement pump is reduced, and the swivel angle of the variable displacement pump can be changed so that the electric motor can again rotate at the desired rotational speed. During this process, maximum power can be obtained from the grid at all times.

[0012] Appropriately, if the hydraulic pump is a constant flow pump, the rotational speed can be maintained at a reduced level until sufficient power is again available to pump the desired amount of hydraulic fluid through at least one hydraulic circuit.

[0013] In another embodiment of the invention, in order to utilize the maximum power offered, the torque generated by the electric motor is adapted in such a way that the deviation of the received power from the maximum power is reduced, in particular minimized. In this way, power control can be realized.

[0014] The construction machine according to the present invention is used for discharging viscous materials. The construction machine can be a mobile construction machine, in particular a towed construction machine or a self-propelled construction machine. The construction machine has a power connection to which a power supply network can be connected depending on the intended purpose. In that case, the supply network provides maximum power at the power connection. To this end, the construction machine comprises an electric motor and an electric control device for operating the electric motor, which can be supplied with power from the supply network. The construction machine further comprises a hydraulic pump driven by the electric motor and supplying a hydraulic circuit of the construction machine. The construction machine further comprises a hydraulic drive supplied with power from the hydraulic circuit.

[0015] In that case, the electric control device is set up to control the electric motor in accordance with the invention and in accordance with the method described above, so that the aforementioned advantages of the method according to the invention also apply to the construction machine according to the invention.

[0016] In an embodiment of the present invention, a construction machine includes a viscous material pump unit capable of pumping a viscous material. The viscous material pump unit is drivingly connected to a hydraulic drive. For example, if the geodesic pump head that the viscous material pump unit must overcome to pump the viscous material changes, the output torque that loads the hydraulic drive may increase. The same applies if a blockage occurs in the delivery line connected to the viscous material pump unit. The delivery line can be used to transport the viscous material delivered by the viscous material pump unit. In the event of such an increase in output torque, controlling the electric motor according to the method of the present invention can avoid overloading the power supply connection, and in particular, tripping the electrical fuse protecting the power supply connection.

[0017] In another embodiment of the invention, the hydraulic pump is designed as a variable displacement pump, in particular in the form of an axial piston pump, with a variable piston stroke. In particular, the piston stroke depends on the adjustable swivel angle of the variable displacement pump. Advantageously, in such a variable displacement pump, the performance of the variable displacement pump can be influenced in very small increments, or even steplessly, by adjusting the piston stroke.

[0018] In another embodiment of the present invention, the swashplate or swashplate of the variable displacement pump acting on the pistons of the variable displacement pump can be set at a predetermined swivel angle relative to the piston stroke to adjust the piston stroke, such a variable displacement pump having the advantage that the adjustment of the piston stroke is very reliable.

[0019] Other advantages and features of the present invention will become apparent from the claims and from the following description of preferred exemplary embodiments of the invention, which is illustrated by the drawings, in which the same reference symbols refer to the same or similar or functionally identical parts.

[0020] It goes without saying that the features mentioned above and those to be described below can be used not only in the respective combinations described, but also in other combinations or alone, without departing from the scope of the invention. [Brief explanation of the drawings]

[0021] [Figure 1] The single FIG. 1 shows diagrammatically the structure of one embodiment of a construction machine according to the invention, set up to carry out the method according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The construction machine 1 according to the invention is used for delivering a viscous material, for example in the form of liquid concrete. The construction machine 1 comprises a power supply connection 2. To the power supply connection 2, an electrical supply network 3 can be connected depending on the intended purpose. In this case, the supply network 3 is an AC voltage network. Alternatively, the supply network 3 can be a DC network, for example the vehicle electrical system of a truck.

[0023] The supply network 3 provides a maximum power at the power connection 2, for example 22 kW or 75 kW. The construction machine 1 further comprises an electric motor 5. The construction machine 1 further comprises an electric control device 6, for example in the form of a frequency converter, for controlling the electric motor 5, which can be powered by the supply network 3. The construction machine 1 further comprises a hydraulic pump 7. The hydraulic pump 7 is driven by the electric motor 5 and supplies a hydraulic circuit of the construction machine 1, which in turn supplies a hydraulic drive 8 of the construction machine 1. The electric control device 6 is designed to operate the electric motor 5 according to the method carried out according to the invention.

[0024] The construction machine 1 includes, for example, a viscous material pump unit 9. The viscous material pump unit 9 can pump a viscous material. In this case, the viscous material pump unit 9 is drivingly connected to a hydraulic drive 8. For example, the viscous material pump unit 9 is drivingly connected to an electric motor 5 via the hydraulic drive 8, a hydraulic circuit, and a hydraulic pump 7. When the hydraulic pump 7 is driven by the electric motor 5, hydraulic fluid is delivered through the hydraulic circuit. The hydraulic fluid delivered through the hydraulic circuit also drives the hydraulic drive 8. The hydraulic drive 8 transmits a driving force to the viscous material pump unit 9. In this case, the hydraulic pump 7 is designed, for example, as a variable displacement pump 10. The variable displacement pump 10 can take the form of an axial piston pump. The variable displacement pump 10 is designed with a variable piston stroke. In this case, the piston stroke can depend on an adjustable swivel angle of the variable displacement pump 10. For example, the swashplate or swashplate of the variable displacement pump 10 acting on the pistons of the variable displacement pump 10 may be set at a predetermined swivel angle relative to the piston stroke to adjust the piston stroke.

[0025] The construction machine 1 can have additional power consumers, which can be connected to the supply network 3, in particular via the same power connection 2, in order to obtain electrical energy for its operation. Such additional power consumers can be, for example, other electric motors for respectively driving various functional units of the construction machine 1. Such functional units can be, for example, a stirrer of the construction machine, a boom pump arranged on the delivery boom, etc. Other additional power consumers can be heaters or lights of the construction machine 1.

[0026] The viscous material pump unit 9 may have a delivery cylinder including a variable-volume delivery chamber. To change the volume of the delivery chamber, particularly in the reverse direction, each delivery cylinder may have a displaceable delivery piston. The viscous material pump unit 9 may further include an S-shaped pipe, one end of which is connected to a discharge pipe that functions as a pump outlet so as to conduct fluid. The S-shaped pipe may be disposed within a storage chamber for storing the viscous material, which can be filled from above. In this case, one end of the S-shaped pipe may be rotatably attached to the discharge pipe within the storage chamber. The variable-volume delivery chamber may open into the storage chamber. Within the storage chamber, the S-shaped pipe may be pivotable relative to the delivery chamber so that it can be alternately connected to one of the delivery chambers so as to conduct fluid. In this way, interaction between the pivoting of the S-shaped pipe and the change in volume of the delivery chamber allows the viscous material in the storage chamber to be alternately sucked in through the delivery chamber and then pumped out through the S-shaped pipe via the delivery chamber and out through the discharge pipe. An agitator can be arranged in the storage chamber of the viscous material pump unit 9. For pivoting relative to the delivery chamber, the S-pipe can be drivingly connected to a hydraulic drive 8. For changing the volume of the delivery chamber, the delivery piston can be drivingly connected to the hydraulic drive 8.

[0027] The method according to the invention is used, for example, for operating a construction machine 1. In that case, the method comprises operating the electric motor 5 by means of a control device 6. The control device 6 is operated by the electric motor 5 in such a way that the incoming power received at the power supply connection 2 does not exceed the maximum power. For example, in that case, when the output torque applied as load to the electric motor 5 fluctuates, the electric motor 5 can be operated in such a way that the maximum power is not exceeded. Furthermore, additional power consumers of the construction machine 1 that can be supplied with electrical energy from the supply network 3 via the same power supply connection 2 can be taken into account when utilizing the maximum power.

[0028] For example, to limit the received power to a maximum power, the torque generated by the electric motor 5 is adjusted so that the received power corresponds to the maximum power. This adjustment can be performed, for example, by means of a control circuit having a controller formed by the electric control device 6.

[0029] The hydraulic pump 7, designed as a variable displacement pump 10, has an operating speed. The variable displacement pump 10 can have optimal efficiency at the operating speed. In that case, the discharge volume of the variable displacement pump 10 is reduced, for example, by correspondingly adjusting the swivel angle, in order to limit the received power to the maximum power. Furthermore, for example, a reduction in the torque generated by the electric motor 5 is performed so that the received power corresponds to the maximum power. In that case, the rotation speed of the electric motor 5 and the variable displacement pump 10 may temporarily drop. Subsequently, the rotation speed can be increased, precisely until the operating speed of the variable displacement pump 10 is reached again. For example, after the received power has been electronically limited in advance, the rotation speed of the variable displacement pump 10 can be increased until the target rotation speed of the electric motor 5 is reached again. As a result of adjusting the swivel angle, the rotation speed of the variable displacement pump can be increased again to the operating speed of the variable displacement pump 10. In that case, the received power remains constant, for example.

[0030] For example, the rotational speed of the hydraulic pump 7 and the rotational speed of the electric motor 5 may be interdependent. The rotational speed of the hydraulic pump 7 and the rotational speed of the electric motor 5 may be interdependent without a gear ratio or via a gear ratio.

[0031] According to the method, for example, the received power is compared with the maximum power in order to detect a possible overload of the power connection. If an imminent overload of the power connection 2 is detected, the electric motor 5 can be operated according to the method to prevent the imminent overload, so that the received power accepted at the power connection 2 does not exceed the maximum power. In order to utilize the maximum power provided, for example, the torque generated by the electric motor 5 is adjusted such that the deviation of the received power from the maximum power is reduced, in particular minimized.

Claims

1. 1. A method of operating a construction machine (1) for delivering a viscous material, the construction machine (1) comprising: a power connection (2) to which a power supply network (3) can be connected according to the intended purpose, said supply network (3) providing a maximum power at said power connection (2); an electric motor (5); an electric control device (6) for operating said electric motor (5), which is supplied with power from said power grid (3); a hydraulic pump (7) driven by the electric motor (5) and supplying the hydraulic circuit; a hydraulic drive unit (8) supplied with hydraulic pressure from the hydraulic circuit; The method comprises: The method comprises the step of operating the electric motor (5) by means of the control device (6) such that the incoming power received at the power connection (2) does not exceed the maximum power.

2. To limit the received power to the maximum power, adjusting the torque generated by the electric motor (5) so that the received power corresponds to the maximum power; is executed 2. The method of claim 1.

3. The hydraulic pump (7) is a variable displacement pump (10) whose swivel angle is adjustable, and the variable displacement pump (10) has an operating rotation speed; To limit the received power to the maximum power, reducing the torque generated by the electric motor (5) so that the received power corresponds to the maximum power; and Reducing the discharge rate of the variable displacement pump (10) by correspondingly adjusting the swivel angle and increasing the rotational speed of the variable displacement pump (10) so that the power received by the variable displacement pump (10) remains constant until the operating rotational speed of the variable displacement pump (10) is reached. is executed 3. The method according to claim 1 or 2.

4. The rotation speed of the hydraulic pump (7) and the rotation speed of the electric motor (5) are mutually dependent. The method according to any one of claims 1 to 3, characterized in that

5. The method comprises: comparing the received power with the maximum power to detect an imminent overload of the power supply connection (2), and operating the electric motor (5) so that the received power received at the power supply connection (2) does not exceed the maximum power in order to prevent the overload. The method according to any one of claims 1 to 4, characterized in that

6. To utilize the maximum power provided, adjusting the torque generated by the electric motor (5) so that the deviation of the received power from the maximum power is reduced, in particular minimized; is executed The method according to any one of claims 1 to 5, characterized in that

7. A construction machine (1) for delivering viscous material, comprising: a power connection (2) to which a power supply network (3) can be connected according to the intended purpose, said supply network (3) providing a maximum power at said power connection (2); an electric motor (5); an electric control device (6) for operating said electric motor (5), which is supplied with power from said power grid (3); a hydraulic pump (7) driven by the electric motor (5) and supplying the hydraulic circuit; a hydraulic drive unit (8) supplied with hydraulic pressure from the hydraulic circuit; A construction machine, wherein the electric control device (6) is configured to operate the electric motor (5) by a method according to any one of claims 1 to 6.

8. The construction machine (1) includes a viscous material pump unit (9) capable of delivering a viscous material; The viscous material pump unit (9) is drivingly connected to the hydraulic drive (8). A construction machine (1) according to claim 7, characterized in that it

9. said hydraulic pump (5) is designed as a variable displacement pump (10), in particular in the form of an axial piston pump, with a variable piston stroke; In particular, the piston stroke depends on the adjustable swivel angle of the variable displacement pump (10). A construction machine (1) according to claim 7 or 8, characterized in that it

10. A swash plate or swash plate of the variable displacement pump (10) acting on the pistons of the variable displacement pump (10) is configurable at the swivel angle relative to the piston stroke to adjust the piston stroke. A construction machine (1) according to claim 9, characterized in that it

Images