Drive for a screed smoothing machine

Abstract

Drive (33) for a device for smoothing viscous concrete, which device comprises a disk (34) or several disks, which disk (34) or disks are rotated on the surface of the liquid concrete with a motion vector essentially parallel to the surface of the concrete, which drive (33) comprises an electric motor, a battery, a gearbox and a control unit, which electric motor drives the disc (34) or discs via a gearbox with a ratio of 1:20 and a drive shaft, which control unit allows a user to specify a predetermined speed of rotation for the electric motor and to control the actual speed of rotation of the electric motor, characterized by the fact that The control unit for limiting energy consumption from the battery when the specified rotational speed changes the actual rotational speed of the electric motor incrementally or continuously or according to a mathematical function over a period of time with a change of 1000-2000 rpm per second.

Description

[0001] The invention relates to a drive for a device for smoothing viscous concrete according to the preamble of claim 1.

[0002] The concrete can be, for example, screed, and this is not a limiting factor. With the device according to the invention, and in analogy to similar power trowels known in the art, the viscous concrete applied during its setting process can be smoothed into a plane. Similar to a power trowel according to the prior art, the device according to the invention comprises at least one disc, which disc is rotated on the surface of the liquid concrete with a movement vector that is substantially parallel to the surface of the concrete. Several rotating discs can also be used. Such smoothing processes are known in the prior art and form the basis for the use of the device disclosed below.

[0003] The device comprises an electric motor as its drive mechanism, which in turn includes a battery for power supply and a control unit for controlling the operating parameters of the electric motor. The electric motor drives at least one disk via a drive shaft.

[0004] For example, the speed of the electric motor can be controlled using the control unit. The control unit allows a user to specify a desired speed for the electric motor and then controls the actual speed of the electric motor.

[0005] US5102258 discloses a device for smoothing screed, but US5102258 does not explicitly or implicitly disclose a power supply via a battery. US5102258, column 1, lines 38ff, specifies a rotational speed of the discs of 75 to 250 revolutions per minute. This appears to be an optimal rotational speed for the discs with regard to friction and the achievable result.

[0006] This is a smoothing result. US5102258 contains no reference to a change or limitation of the rate of change of the rotational speed of the disks or the motor during a start-up phase.

[0007] CA2664221 contains no reference to a numerical specification of the rate of change of the rotational speed of the discs of a device for smoothing screed. CA2664221 does not explicitly mention a battery for power supply.

[0008] US200821976

[0022] merely indicates that the drive may be a speed-controlled electric motor. The figure description in US200821976

[0024] mentions a fuel tank (“fuel tank 12”). The motor's speed is controlled by the position of the holding device. US200821976 makes no explicit reference to the use of a battery as an energy storage device. Furthermore, US200821976 does not provide any numerical indication of the rate of change of the rotational speed when starting the motor.

[0009] US2020318367A1 also does not disclose the rate of change of rotational speed of an electric motor, which electric motor is connected to a battery.

[0010] EP1529898A1

[0015] explicitly mentions an internal combustion engine. EP1529898 A1 does not contain a numerical specification of a rate of change for the rotational speed of an electric motor powered by a battery.

[0011] EP887489A1 discloses a changing device for changing the discs, which changing device is based on the use of adhesive.

[0012] DE1683168A1 discloses a system for attaching smoothing discs to a drive axle, but does not disclose a lever system for this purpose.

[0013] DE102017214119A1 (Applicant Robert Bosch GmbH) discloses a quick-release clamping device for a portable machine tool.

[0014] The family of DE102004020982A1, which is listed as prior art in the register for DE102017214119A1, also includes the European patent EP1737616B1.

[0015] The family of DE102012004458A1, which is cited as prior art in the register for DE102017214119A1, also includes international patent application WO2013131676A2. WO2013131676A2 discloses a self-tightening system, which system is designed such that a force deviating from the axial direction of a spindle generates a fastening force in the axial direction of the spindle.

[0016] The patent family for DE202013006901U1, which is listed as prior art in the register for DE102017214119A1, includes the European patent EP3027361B1.

[0017] Documents US2005254896, US2020263443 and DE202013006901U1 do not describe devices for smoothing viscous concrete with battery-powered electric motors that, when the rotational speed is changed, alter the actual rotational speed of the electric motor over a certain period of time by a change of 1000-2000 rpm per second.

[0018] The devices mentioned above partially include an electric motor for driving the discs. The electric motors are presumably powered via a power cable. In contrast, however, the device according to the invention includes a battery for power supply, as explicitly mentioned above.

[0019] Using a battery as an energy source with limited power places special demands on the control of the electric motor. When driving at least one disc, the friction between the disc and the viscous concrete must be overcome within a timeframe acceptable to the user. Furthermore, care must be taken to use the limited energy stored in the battery sparingly.

[0020] The resulting technical problem to be solved is solved by a special control system for the electric motor.

[0021] According to the invention, the technical problem is solved by claim 1.

[0022] According to the invention, the technical solution is characterized in that the control unit for limiting the energy withdrawal from the battery changes the actual revolutions of the electric motor incrementally or continuously or following a mathematical function over a period of time with a change of 1000-2000 rpm per second when the specified revolutions are changed.

[0023] The electric motor has a first rotational speed at time t1, i.e. the drive shaft of the electric motor rotates at a first rotational speed at a first time t1.

[0024] The initial rotational speed can be zero. The electric motor can be at a standstill at the initial point in time. The disc, driven by the electric motor, and the viscous concrete are subject to a static frictional bond.

[0025] For the electric motor to have a second rotational speed at a second time t2, which differs from the first rotational speed, the motor's rotational speed must be changed over a period of time. In the example mentioned, the rotational speed is increased from a value of zero (first rotational speed) to a value greater than zero (second rotational speed).

[0026] This increase in rotational speed from a standstill to a rotating motion of the disc necessitates overcoming the static friction acting between the disc and the viscous concrete. Overcoming this static friction is, according to established principles, an energy-intensive process, which is why the inventor defines limits based on the change in rotational speed per unit of time.

[0027] Similarly, increasing a first rotational speed above zero to a second rotational speed requires overcoming the sliding friction between the disc and the surface of the viscous concrete. The limits on the change in rotational speed set by the inventor also prove advantageous here.

[0028] The limits set by the inventor for changing the rotational speed can be seen as an optimization between the requirement of using the energy stored in the battery sparingly and the requirement of the shortest possible, or at least user-friendly, time period for changing the rotational speed. The limits specified by the inventor have the technical effect of limiting the energy drawn from the battery. This prevents the energy stored in the battery from being used essentially only to start the rotation of the disc.

[0029] The specified limits represent an optimization between the required additional energy expenditure and the duration of the time interval. The additional energy expenditure refers to the energy required to increase the initial rotational speed.

[0030] The specified limits on the rate of change of the rotational speed have a similar effect on the control of the electric motor as limiting the torque applied by the electric motor. However, the specified rate of change of the electric motor's rotational speed can be measured and controlled by simpler means.

[0031] Viscous screed or concrete always exhibits approximately the same coefficient of static and sliding friction with a rotating metal disc. A device for smoothing viscous concrete or screed is further characterized by the fact that a constant force is applied to the viscous concrete or screed during the smoothing process. For this reason, determining the torque is unnecessary, since the frictional force acting between the at least one disc and the viscous concrete or screed is essentially constant anyway.

[0032] The solution presented here concerns changing the rotational speed to zero of a stationary electric motor and a stationary disk.

[0033] The solution presented here concerns changing the rotational speed of a rotating electric motor and a rotating disc.

[0034] The aforementioned change in rotational speed can, for example, be made in stages and thus incrementally.

[0035] The aforementioned change in rotational speed can be achieved by following a mathematical function. One possible change in rotational speed following a mathematical function is a linear and therefore continuous change. The rotational speed can also be changed by following a sinusoidal curve.

[0036] According to conventional theory, sliding friction depends on the relative velocity at the friction surface. In this case, the sliding friction depends on the relative velocity between the disk and the viscous concrete. The mathematical function can account for this sliding friction, which varies with the relative velocity. The mathematical function can describe a change in rotational speed, such that the rotational speed changes with a substantially constant energy input.

[0037] The drive according to the invention can be characterized by the fact that the change in the number of revolutions is 1500 rpm / sec.

[0038] The drive according to the invention can be characterized in that the maximum speed of the electric motor is 3300 rpm and the maximum speed of the disc is 165 rpm.

[0039] The device comprising the drive according to the invention can include a transmission connected between a drive shaft of the electric motor and a disc shaft driving the disc. The transmission can have a gear ratio of 3300:165 = 1:20.

[0040] The specified rotational speed of the disc is chosen with regard to the required energy input, the sliding friction, and the work progress. The specified gear ratio is also chosen with regard to the aforementioned parameters.

[0041] The device disclosed herein according to the invention also relates to a detachable fastening device for the disc on the drive shaft. It is also conceivable that the fastening device described herein is implemented independently of the other features of the drive according to the invention, such as the control device.

[0042] The drive according to the invention can be characterized in that the at least one disc is attached to the drive shaft by means of a releasable locking device, which locking device comprises locking levers, which locking lever is hinged at one end to a pivot point on the drive axle, which locking lever includes a free end for receiving the disc, which locking lever can be adjusted from a closed position holding the disc(s) clamped to an open position releasing the disc(s) by means of a lever mechanism, wherein the locking lever, in the closed position, contacts a projection in a disc with its longitudinal side.

[0043] Movement of the locking lever can be blocked in the closed position, which clamps at least one disc, by means of a locking device according to the prior art. The locking lever, which receives the disc with its free end, is capable of applying a high clamping force to the disc.

[0044] The locking lever extends radially from the drive axis and is essentially parallel or inclined to a disk surface.

[0045] The disc surface includes a projection which the locking lever contacts with its longitudinal side. In this way, torque can be applied from the drive shaft to the disc via the lever and the projection. The lever cannot contact the projection in its open position and therefore only does so in its closed position, allowing the disc to be easily removed even if the lever and projection become jammed.

[0046] The drive according to the invention can be characterized in that the locking lever is rigidly coupled to an actuating lever, which actuating lever is attached to the pivot point.

[0047] The locking lever and the actuating lever are mounted in a rigid position relative to each other, yet rotatable around the pivot point. The locking device, comprising the locking lever and the actuating lever, can be moved from an open position to a closed position by rotating the locking lever and the actuating lever around the pivot point.

[0048] The drive according to the invention can be characterized in that two locking levers and two actuating levers form a scissor lever, which scissor lever at the free ends of the actuating levers each includes an elongated hole,

[0049] in which elongated hole an actuating axis extending through both actuating levers can be moved.

[0050] Moving the actuating shaft within the elongated hole moves the locking device from a closed to an open position and vice versa. This movement of the actuating shaft is characterized by the ability to apply a high clamping force.

[0051] The invention disclosed herein also relates to a method for controlling a drive of a device for smoothing viscous concrete.

[0052] The device comprises at least one disk, which disk is rotated relative to a surface of the concrete with a motion vector directed parallel to the surface of the concrete.

[0053] The drive system comprises an electric motor with a drive shaft, which is coupled to a disc shaft that drives the discs. The electric motor is powered by a battery.

[0054] The drive system also includes a control unit, which allows the operation parameters of the electric drive to be controlled, such as the rotational speed of the drive axle or the rotational speed of the electric motor. The control unit allows the input of a predefined number of revolutions per minute for the electric motor and the output of the actual rotational speed of the electric motor.

[0055] The drive system is designed so that the electric motor drives the disc.

[0056] The above-mentioned task is to be applied to the device according to the invention as well as to the method according to the invention.

[0057] The solution according to the invention is achieved by claim 5.

[0058] According to the invention, this is achieved by changing the actual number of revolutions of the electric motor by 1000-2000 rpm per second incrementally or continuously or following a mathematical function over a period of time.

[0059] The method according to the invention can be characterized by the fact that The change in the actual rotational speed of the electric motor is limited to 1500 rpm / sec.

[0060] The invention is further explained with reference to the following embodiments shown in the figures: Fig. Figure 1 shows a diagram of the rotational speed profile when applying the method according to the invention. Fig. Figure 2 shows a cross-sectional view of an embodiment of the locking device in the open position. Fig. Figure 3 shows a cross-sectional view of the in Fig. 2 shown embodiment of the locking device in a closed position.

[0061] The embodiments shown in the figures merely illustrate possible embodiments. It should be noted that the invention is not limited to these specifically depicted embodiments, but also encompasses combinations of the individual embodiments with one another and combinations of an embodiment with the general description given above. These further possible combinations need not be explicitly mentioned, as they are within the knowledge of a person skilled in the art in this technical field, given the teaching provided by the present invention.

[0062] The scope of protection is defined by the claims. However, the description and drawings must be consulted for the interpretation of the claims. Individual features or combinations of features from the different embodiments shown and described can, in themselves, constitute independent inventive solutions. The problem underlying these independent inventive solutions can be found in the description.

[0063] In the figures, the following elements are identified by the preceding reference symbols: 1 (free) 2 (free) 3 (free) 4 (free) 5 locking levers 6 locking levers 7. Linkage point 8 hinged end locking lever 9 hinged end locking lever 10 free end locking lever 11 free end locking lever 12 Holding device disc 13 operating levers 14 operating levers 15 free end actuating lever 16 free end actuating lever 17 elongated holes 18 elongated holes 19 Slotted hole axis Slotted hole 20 Slotted hole axis Slotted hole 21 Actuating axis 22 Protrusion Locking Lever 23 Protrusion Locking Lever 24 holes in holding device 25 Underside Holding device 26 Intervention element 27 polygonal section 28 Extension axis 29 (free) 30 Steering axle 31 Top plate 32 holes in mounting plate 33 Drive 34 discs 35 levers 36 Handle Lever 37 control levers 38 carrying levers 39 Locking element 40 Carrying handle

[0064] The Fig. Figure 1 shows a diagram in which the rotational speed of the electric motor or drive axle is plotted on the ordinate (y-axis). No values ​​are shown in the diagram; this diagram serves solely to illustrate the relationships between the values.

[0065] The abscissa (x-axis) is a time axis.

[0066] The diagram of Fig. Figure 1 serves to illustrate the method according to the invention and the functioning of the device according to the invention, in particular the control device.

[0067] The method according to the invention serves to control a drive for a device used to smooth viscous concrete. The control system described below has the technical effect of limiting the amount of energy drawn from the battery by the motor during changes in motor speed. This allows the required battery capacity, and therefore the battery size, to be kept small. It prevents the majority of the energy stored in the battery from being used when accelerating the disc, particularly when accelerating from a standstill.

[0068] The device comprises at least one disk, which disk is rotated relative to a surface of the concrete with a motion vector directed parallel to the surface of the concrete.

[0069] The drive system comprises an electric motor, a battery and a control unit, with the electric motor driving the disc.

[0070] It is in the diagram of Fig. 1 at time t1 a first rotational speed 1 of the electric motor or the drive shaft of the electric motor or the disk or a disk shaft for driving the disk is entered. Fig. Paragraph 1 concerns the special case where the rotational speed is zero at the first time t1. The elements mentioned above remain stationary. The person skilled in the art can determine from the Fig. 1 and the description of this derivable doctrine also apply to a rotational speed other than zero at time t1.

[0071] The control unit allows the input of a predefined number of revolutions for the electric motor. In the simplest case, this can be achieved by starting the device, which then automatically sets the desired number of revolutions. Therefore, the number of revolutions is not limited to a numerical input.

[0072] The control unit can also allow numerical input of the number of revolutions. For example, the user can enter a speed depending on the properties of the concrete to be smoothed.

[0073] The control unit allows the output of the actual revolutions per minute of the electric motor.

[0074] Inputting a speed that differs from the actual speed of the electric motor implies a necessary change in the actual number of revolutions of the electric motor. The method according to the invention provides that the speed of the electric motor is changed by 1000-2000 rpm in a period lasting one second, and thus per second, to limit the energy extraction from the battery.

[0075] It is therefore - with reference to the diagram of the Fig. 1 - The rotational speed is increased from the value of the first rotational speed 1 to the value of the second rotational speed 2. The rate of change of the rotational speed per second is 1000-2000 rpm. In one second, the rotational speed changes by 1000-2000 rpm. In the case of the Fig. 1. Changing the rotational speed is an increase in rotational speed.

[0076] The change in rotational speed can, for example, be carried out following a linear function 3.

[0077] The change in rotational speed can, for example, be carried out following a mathematical function, which mathematical function 4 has a horizontal tangent at the first time t1 and at the / or second time t2.

[0078] It is also conceivable that the change in rotational speed occurs incrementally and thus in stages.

[0079] The above-mentioned change in rotational speed of 1000-2000 rpm per second is an optimization with regard to keeping energy input (or energy output from the battery) to a minimum and a duration of time acceptable to the user for the change in rotational speed.

[0080] In a semi-technical device, the change in the actual rotational speed of the electric motor is limited to 1500 rpm per second.

[0081] Fig. Figure 2 shows a vertical sectional view of an embodiment of a locking device in the open position. Fig. Figure 3 shows a vertical cross-sectional view of the in Fig. 2 shown embodiment in the closed position.

[0082] The function of the locking device is to detachably secure the disc to the drive shaft, if necessary via a fastening device mounted on the disc, so that rotation of the shaft causes rotation of the disc. This is demonstrated in particular by the Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6. The detachable fastening of the disc to the axle is discussed.

[0083] The figure description does not differentiate between a drive axle and a disc axle as defined in the general description.

[0084] The locking device comprises a locking lever 5, 6, which engages locking levers 5, 6 at each of its ends 8, 9 in the Fig. The drive axle (not shown) is articulated at a pivot point 7. The pivot point 7 can, for example, be formed by a pivot axis 30 (see explanation below), which pivot axis 30 is arranged at an angle of 90 degrees to the longitudinal axis of the drive axle. The in Fig. 2 and Fig. The embodiment shown in Figure 3 comprises a pivot axis 30, which pivot axis 30 is normal to the plane of the image. Fig. 2 and the Fig. 3 extends. The linkage axis 30 can also have the task of transmitting the torque applied via the drive axis to the locking levers 5, 6.

[0085] The locking levers 5, 6 engage in free ends 10, 11 for receiving the in the Fig. 2 and in the Fig. 3 unregistered discs. The Fig. Figure 2 shows a step-shaped free end 10, 11 with each a projection 22, 23, which projections 22, 23 are designed for making an engagement with a holding device 12 on the disk or a holding device arranged on the disk.

[0086] Each locking lever 5, 6 has an actuating lever 13, 14 rigidly connected to it. The actuating levers 13, 14 are rotatably mounted about the pivot point 7, either directly or indirectly via the locking lever 5, 6. A rotational movement of an actuating lever 13, 14 always causes a movement of the locking lever 5, 6 rigidly connected to the respective actuating lever 13, 14.

[0087] The angle extending between a locking lever 5, 6 and an actuating lever 13, 14 connected to the respective locking lever 5, 6 can change due to elastic deformation in the rigid connection area between the levers 5, 6, 13, 14. This can create a preload effect when clamping the disc or the holding device 12 with the locking levers 5, 6.

[0088] It is essentially a question of dimensioning whether a detectable elastic deformation is permitted between a locking lever 5, 6 and an actuating lever 13, 14 connected to the respective locking lever 5, 6. The rigid connection of an actuating lever 13, 14 to the respective locking lever 5, 6 can also be designed so rigidly that no elastic deformation is detectable or measurable.

[0089] The locking levers 5, 6 and the actuating levers 13, 14 form a scissor lever. The levers 5, 6, 13, 14 of the scissor lever are rotatably mounted about the pivot point 7.

[0090] The scissor lever includes an elongated hole 17, 18 at each of the free ends 15, 16 of the actuating levers 13, 14. The longitudinal axes 19, 20 of the elongated holes 17, 18 extend in the open position of the locking device (see Fig. 2) and in the closed position of the locking device (see Fig. 3) as geometric rays passing by pivot point 7. An actuation axis 21 extends through the elongated holes 17, 18. The actuation axis 21 is arranged at an angle of 90° to the levers 5, 6 and 13, 14. The actuation axis 21 extends at a right angle to the image plane of the Fig. 2 and the Fig. 3.

[0091] A movement of the actuating axis 21 in the elongated holes 17, 18 leads to a movement of the levers 5, 6 and 13, 14. This presses the free ends 10, 11 of the locking levers 5, 6 against the holding device 12 of the disc.

[0092] It is the locking device by a movement of the actuating axis 21 in both elongated holes 17, 18 from an open position (see Fig. 2) into a closed position (see Fig. 3) transferable. The actuating axis 21 can be locked in its movement in the elongated holes 19, 20 by a locking device according to the prior art.

[0093] The locking device may, in addition to or as an alternative to the locking device, include a spring, which spring is located in the Fig. 2 and in the Fig. 3 is not entered. The spring experiences an increase in preload when the locking device moves from the closed position to the open position.

[0094] The increase in spring preload can be achieved, for example, by moving the actuating axis 21 when the spring is linked at one end to the actuating axis 21.

[0095] An increase in the spring preload can occur, for example, when a torsion spring is connected to mutually rotating levers 5, 6, 13, 14, through the rotational position of the levers 5, 6, 13, 14. For instance, a torsion spring can be connected to the actuating levers 13, 14, which experiences preload when the actuating levers 13, 14 are rotated from the closed position to the open position.

[0096] It is mentioned above that the longitudinal axes 19, 20 of the elongated holes 17, 20, or the geometric rays passing through these longitudinal axes 19, 20, do not pass through the pivot point 7. This creates a leverage effect of the movement of the actuating axis 21 on the resulting forced movement of the scissor lever. The actuating axis 21, the actuating levers 13, 14, and the locking levers 5, 6 form a mechanical constraint system.

[0097] The Fig. Figure 4 shows a view of the locking device from below. Based on the Fig. 4. The expert will understand how the torque is transferred from the drive axle to the disc. Fig. Figure 4 does not include a representation of the drive axle and the disc.

[0098] The Fig. Figure 4 shows the holding device 12 arranged on the disk. The holding device 12 includes bores 24 by means of which the holding device 12 can be detachably attached to the disk by screws. This creates a connection between the holding device 12 and the disk suitable for transmitting torque.

[0099] The further description concerns the manufacture of a device for transmitting a torque between the drive axle and the locking levers 5, 6 on the one hand and the holding device 12 on the other.

[0100] The Fig. Figure 4 shows the locking levers 5, 6 in their closed position. The free ends 10, 11 of the locking levers 5, 6 are pressed against or engaged with the underside 25 of the holding device 12. The holding device 12 advantageously includes a recess for forming the underside 25. The plane of the underside 25 is spaced at a distance from the plane with the bores 24, so that the levers 5, 6 do not interfere with the smoothing process by the disk or contact the disk.

[0101] The Fig. Figure 4 shows the levers 5 and 6 in the closed position. In addition to the levers 5 and 6, the locking device comprises at least one engagement element 26, which is guided through a corresponding cutout in the underside 25 and engages with the plate forming the underside 25. The engagement element has a polygonal base for transmitting the torque to the plate forming the underside 25.

[0102] The Fig. Figure 5 shows the locking device. Fig. Figure 6 shows only the holding device 12.

[0103] The holding device 12 comprises a bottom surface 25 with a polygonal cutout 27 for receiving the engagement element 26 of the locking device, which has a polygonal shape in its plan view. The holding device 12 includes bores 24 in a plane spaced apart from the bottom surface 25 for releasably fastening the holding device 12 to the disc.

[0104] The locking device in Fig. 5 includes the locking levers 5, 6 described above, which locking levers 5, 6 are located in the Fig. The locking levers 5 and 6 are in an open position as shown in Figure 5. They are arranged concentrically around the axis of extension 28 and between two engagement elements 26. The longitudinal sides of the locking levers 5 and 6 contact the surfaces of the engagement elements 26 facing the longitudinal sides.

[0105] The engagement elements 26 are arranged centrally around the longitudinal axis 28.

[0106] It is in the Fig. Figure 5 shows the pivot axis 30 of the aforementioned scissor lever, which forms the pivot point 7. The pivot axis 30 can extend at a right angle to the axis of extension of a drive shaft connected to an electric motor. The pivot axis 30 can extend through the wall of the drive shaft to create a torque-transmitting connection.

[0107] The locking device further comprises a mounting plate 31 with bores 32. The locking device can thus be detachably attached to the drive shaft by screwing screws through the bores 32 into the wall of the drive shaft. When the locking device and the holding device 12 are brought together, the plate forming the underside 25 and the mounting plate 31 are brought into contact with each other.

[0108] The locking levers 5, 6 allow the mounting plate 31 and the plate forming the underside 25 to be pressed together.

[0109] The Fig. Figure 6 shows a view of the holding device 12. The holding device 12 includes bores 24 for receiving screws to fasten the holding device 12 to the disk (not shown).

[0110] It is in the Fig. 6 the polygonal section 27 is clearly visible. As in Fig. Figure 5 shows that the levers 5 and 6, together with the polygonally shaped engagement elements 26, are inserted into this cutout 27. The shapes of the elements 5, 6, and 26 to be inserted and the shape of the cutout 27 are designed accordingly.

[0111] The Fig. Figure 7 shows a possible arrangement of the locking device in one axis. The locking device is in the closed position.

[0112] Furthermore, it is the disc in the Fig. 7 entered.

[0113] To maintain clarity of the Fig. 7 are in the Fig. 7. Only the essential elements are marked with a reference sign.

[0114] The Fig. 8 and the Fig. Figure 9 includes a side view of a possible embodiment of the screed smoothing machine according to the invention. The screed smoothing machine comprises at least one disc, which disc 34 is rotated on the surface of the liquid concrete with a movement vector substantially parallel to the surface of the concrete. For this purpose, the disc 34 is driven by a drive 33 as described above, which drive 33 comprises an electric motor, a battery, and a control unit. The drive 33, in particular the electric motor, drives the disc 34 via a drive shaft. The electric motor as drive 33 is controlled by a control unit, which allows a user to specify a predetermined speed of rotation for the electric motor and to control the actual speed of rotation of the electric motor.

[0115] The screed smoothing machine includes in the Fig. 8 and in the Fig. In the embodiment shown in Figure 9, a lever 35 is provided for guiding the screed trowel on the concrete to be troweled. The lever 35 extends from the screed trowel, preferably from a region of the screed trowel adjacent to the sliding plate 34, to a height at which a user can easily grasp the handles 36 provided at the free end of the lever 35. A control lever 37 is also arranged at the free end of the handle 36. The control lever 37 must be pulled to operate the drive 33. If the user does not pull the control lever 37, the drive 33 is stopped.

[0116] The lever 35 can be arranged at one end of the screed smoothing machine. The lever 35 is preferably articulated to the screed smoothing machine, the inclination of the lever 35 being adjustable by a locking element 39.

[0117] A support lever 38 is arranged at the opposite end of the screed trowel. Advantageously, the support lever 38 is arranged on a region of the screed trowel adjacent to the disc 34. In a particularly advantageous manner, the support lever 38 is articulated to the screed trowel so that it is guided by a Fig. 8 shown custody in one in the Fig. 9. The carrying lever 38 can be moved to the operating position as described in the... Fig. 8 and in the Fig. Figure 9 shows that the carrying lever 38 has a curved shape, allowing it to be stored in a space-saving manner in a form extending around the drive 33. In the stored position, the carrying lever 38 acts as a protective bracket for the drive 33.

[0118] The carrying lever 38 can include a carrying handle 40.

[0119] The screed smoothing machine can be carried by two people, with one person lifting the screed smoothing machine at the carrying lever 38 and one person lifting the screed smoothing machine at the lever 35.

[0120] The expert recognizes that the Fig. 8 and the Fig. The arrangement of the support lever 38 and the lever 35 described in 9 can be implemented independently of the type of drive. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 5102258 [0005, 0006] CA 2664221

[0007] US 200821976

[0008] US 2020318367A1

[0009] EP 1529898A1

[0010] EP 887489A1

[0011] DE 1683168A1

[0012] DE 102017214119A1 [0013, 0014, 0015, 0016] DE 102004020982A1

[0014] EP 1737616B1

[0014] DE 102012004458A1

[0015] WO 2013131676A2

[0015] DE 202013006901U1 [0016, 0017] EP 3027361B1

[0016] US 2005254896

[0017] US 2020263443

[0017]

Claims

[1] Drive (33) for a device for smoothing viscous concrete, which device comprises a disk (34) or several disks, which disk (34) or disks are rotated on the surface of the liquid concrete with a motion vector essentially parallel to the surface of the concrete, which drive (33) comprises an electric motor, a battery, a gearbox and a control unit, which electric motor drives the disc (34) or discs via a gearbox with a ratio of 1:20 and a drive shaft, which control unit allows a user to specify a predetermined speed of rotation for the electric motor and to control the actual speed of rotation of the electric motor, characterized by , that The control unit for limiting energy consumption from the battery when the specified rotational speed changes the actual rotational speed of the electric motor incrementally or continuously or according to a mathematical function over a period of time with a change of 1000-2000 rpm per second. [2] Drive according to claim 1, characterized by that the change in revolutions per minute is 1500 rpm / sec. [3] Drive according to one of claims 1 to 2, characterized by , that the maximum speed of the electric motor is 3300 rpm and the maximum speed of the disc is 165 rpm. [4] Drive according to any one of claims 1 to 3, characterized by , that the disc or discs are attached to the drive shaft by means of a releasable locking device, which locking device includes locking levers (5, 6), which locking lever (5, 6) is articulated at one end (8, 9) to the drive shaft at a pivot point (7), which locking lever (5, 6) includes a free end (10, 11) for receiving the disc, which locking lever (5, 6) can be set from a closed position holding the disk(s) clamping to an open position releasing the disk(s) by means of a lever mechanism, wherein the locking lever (5, 6) in the closed position contacts a projection in a disk with its longitudinal side. [5] Drive according to claim 4, characterized by , that the locking lever (5, 6) is rigidly connected to an actuating lever (13, 14), which actuating lever (13, 14) is articulated at the pivot point (7). [6] Drive according to claim 5, characterized by, that two locking levers (5, 6) and two actuating levers (13, 14) form a scissor lever, which scissor lever at the free ends (15, 16) of the actuating levers (13, 14) each includes an elongated hole (17, 18) in which elongated hole (17, 18) an actuating axis (21) extending through both actuating levers (13, 14) is movable. [7] Control unit for carrying out a method for controlling a drive of a device for smoothing viscous concrete, which device includes one or more discs which disk or disks are rotated to a surface of the concrete with a motion vector directed parallel to the surface of the concrete, which drive comprises an electric motor, a battery and a control unit, which electric motor drives the disc(s), which control unit allows the input of a predetermined number of revolutions of the electric motor and the output of an actual number of revolutions of the electric motor, characterized by , that a change in the actual number of revolutions of the electric motor by 1000-2000 rpm per second over a period of time, incrementally or continuously or following a mathematical function. [8] Control unit for carrying out a method according to claim 7, characterized by , that the change in the actual rotational speed of the electric motor is limited to 1500 rpm / sec.

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