WO2014131896A2

WO2014131896A2 - Hand truck with electric drive

Info

Publication number: WO2014131896A2
Application number: PCT/EP2014/053978
Authority: WO
Inventors: Christian Foder
Original assignee: Christian Foder
Priority date: 2013-02-28
Filing date: 2014-02-28
Publication date: 2014-09-04
Also published as: DE102013102020A1; WO2014131896A3

Abstract

The invention provides a hand truck (1) with an electric drive (9) for driving at least two coaxially arranged driven wheels (7a, 7b) of the hand truck (1), an operator control component (15), a controller for controlling the electric drive (9) and an inclination sensor (25) for determining an inclination position of the hand truck (1), wherein the controller is configured in such a way that it keeps the hand truck (1) in a desired inclination position by means of the electric drive (9).

Description

Hand truck with electric drive

The invention relates to a sack truck with an electric drive for driving at least two coaxially arranged drive wheels of the sack truck and with a control panel for controlling the electric drive. Furthermore, the invention relates to a method for controlling a sack truck.

Sack trucks are widely used two-wheeled carts for carrying loads. The wheel hub is usually at the same time the mechanical fulcrum in sack trucks.

In addition to the transport of bags, depending on the design of the sack truck, objects of various kinds, such as parcels or crates, can be moved. The intended use according to the sack carts differ in length and shape of the support means. The support means can be hinged or height adjustable. Modern sack trucks are fully rubber or pneumatic. For transporting heavy objects by stairs, sack trucks with star wheels are available in which three or five wheels are rotationally arranged about their axis about an axis.

Sack trucks offer a particularly agile and flexible transport option for transport goods. Here, they are systems with several consecutively arranged axes, as described for example in DE 20 2007 01 5 278 U1, superior.

In particular, for transport by stairs sack trucks are available with electric drive. Such a drive is known for example from DE 297 08 841 U1. However, with the electric powered sack truck available, there is a problem in an uncontrolled tilting of the sack truck about the fulcrum and consequent difficulties in controlling the cargo or collision of the sack truck with the operator. Furthermore, holding the sack truck in a desired pivoting position is strenuous for the operator, especially when very heavy goods to be transported with the sack truck. Furthermore, the operator often blocks the transport route himself during close maneuvering Do not set it far enough to turn so that it can not turn in narrow passages. Since he has to keep the sack truck in balance, his location is not freely selectable. This results in disadvantages in the flexibility of a conventional electrically driven sack truck.

From US 5,701,965 an electrically driven one-person transport with only two wheels lying on the same axis, between which the person being transported stands and which holds itself by an electronic drive control in balance, known. The person is thereby to control on the means of transport. An autonomous method for transporting loads in confined spaces is not provided.

It is therefore an object of the present invention to provide a hand truck with electric drive, which is particularly easy to handle.

According to the invention this object is achieved by a sack truck and a method for controlling a sack truck with the features of the independent claims. In the subclaims there are advantageous embodiments and improvements of the invention.

The sack truck according to the invention thus has an electric drive for driving at least two coaxially arranged wheels of the sack truck, a control unit, a controller for controlling the electric drive and a tilt sensor for determining a tilt position of the sack truck, wherein the controller is set up so that it is controlled the sack truck on the electric drive in a desired inclination position, can hold. An inclination sensor in the sense of the invention can be, for example, a gyroscope or a different type of component with which a change in the spatial position of the sack truck can be measured.

Under a tilt position of the sack truck is a situation to understand, for example, as a relative position of the inclination sensor to a straight line through the support points of the wheels on a substrate on which the sack truck is related. If the weight force vector of the sack truck engaging the center of gravity of the sack truck cuts the straight line, the sack truck is in balance. In the case of a loaded hand truck, the center of gravity shifts in relation to an unloaded hand truck. The loaded sack truck is in balance when the loaded in the center of gravity of the loaded sack truck weight force vector of the loaded sack truck cuts the straight line. The electric drive can then keep the sack truck in balance by small reciprocating movements. This is made possible by the tilt sensor, which detects the inclination position of the sack truck and reports to the controller with a control. If the controller determines with the regulation that the weight force vector no longer intersects the straight line, then the controller triggers a corresponding compensating traversing motion of the electric drive so that the straight line passing through the support points of the wheels on the ground intersects the weight force vector again (Inverse pendulum). This keeps the sack truck in the desired inclination position. The operator no longer has to keep the sack truck in balance, but can focus on the method of the sack truck. As a result, the handling of the sack truck over a conventional sack truck with electric drive is greatly improved. The operator is also less physically stressed, especially in the case of heavy transport goods to be transported. Further, the operator gains greater flexibility in position relative to the sack truck, which enhances maneuvering in confined spaces.

Further, the controller may be placed in various modes of operation via a selector switch during operation, the modes of operation including, but not limited to, a manual drive mode and a motorized drive mode. In the manual drive mode, the hand truck is to be used as a non-electrically driven hand truck, whereas in the motorized drive mode, the hand truck supports the operator by the electric drive. Movements such as picking up a load or pinpointing it must be done quickly, so that the use of the sack truck is economical. Since the operator can often perform these movements very quickly, it is correspondingly advantageous if he can select in the operating mode between a manual drive mode and a motorized drive mode. In order not to have to interrupt the work processes, it is advantageous that this can also be done during operation. On the one hand, the user does not feel restricted in a possibly too slow response of the electric drive. At the same time, the effort in the control, regulation and the sensor can be reduced to the degree that is necessary for the support of the operator by the electric drive. As a result, the sack truck can be produced more cheaply.

In a further development, in the case of a motorized drive mode, the control can additionally be set into an operating mode with a motorized, stabilized drive, in which the control system controls the sack truck by means of the electric drive Holding yourself in balance near a desired position. As a result, the operator in the handling of the sack truck is maximally relieved, and can fully concentrate on the environment, such as obstacles. At the same time, without interrupting the movement, the operator can choose between the different modes of operation, if required by the situation or his own comfort.

An advantageous development of the sack truck provides that the control unit has at least one handle, wherein the handle may comprise at least one steering sensor which detects a steering movement. For the handling of sack trucks, it has proven to be advantageous if the control unit has two of the at least one handle, since the operator can grasp the sack truck with both hands. With the help of the at least one steering sensor intended by the user cornering is detected by the steering movement and passed as a steering command to the controller with control. The control with regulation causes a cornering of the sack truck in that the electrically driven wheels rotate at different speeds. Either the inside wheel is slower or the outside wheel driven faster. For rotation on the spot, the wheels can also be driven in opposite directions.

The steering sensor may also be a pressure sensor, which measures the force exerted on the handle by the user during a steering movement. Furthermore, it is advantageous that each of the at least one handle laterally comprises at least two of the at least one steering sensors. As a result, the sack truck can also operate with one hand, since the at least one handle can forward both steering movements to the left and right or the resulting forces to the controller with regulation.

Since the implementation of the steering movement in a cornering by the controller with a control, the sack truck can be intuitively steered by the operator. The user does not have to get used to a steering system in which the user drives through a direct influence on the rotational speed of the wheels with the hand truck curves. Instead, he can focus on the track to avoid obstacles, for example.

Further, a separate control is provided on the control panel for each of the wheels. As a control, a control lever, a rotary handle or the like can be used. Even if the sack cart can be intuitively guided by the at least one steering sensor on the at least one handle, the control with closed-loop control makes it sensible for the user to directly adjust the rotational speed of each individual Can individually steer Rades. As a result, the sack truck can be ranked particularly fine and flexible.

According to one embodiment, the operating part is provided on the hand truck so that it can be displaced relative to a frame of the hand truck. Thus, the control panel may be formed in the manner of a drawbar. The control panel can thereby be operated by the user while standing, while the sack truck is moving, in particular rotates or tilts. This makes operation easier, since the operator does not have to move completely synchronously with the sack truck or has to move to the desired position by his own movement. Furthermore, the operator can take a relatively freely selectable position to the sack truck, which facilitates maneuvering in confined spaces.

The control panel is for example a cable with the sack truck, i. connected to a controller of the electric drive. The cable can also be provided so that it automatically rolls in, so that only the cable length just required is pulled out. This facilitates handling.

Alternatively, the control panel via a wireless, especially a wireless connection, networked with the electric drive. This allows further flexibility in handling the sack truck, as the operator can disconnect from a cable unattached from the sack truck while operating it. By means of the radio connection, for example, a plurality of digitally-proportional command channels are realized. This allows for proportional control wherein the controlled size of the controlled hand truck, such as the pitch position, may be proportional to the position of the control on the keypad. A tilt sensor on the sack truck supports this inclination setting.

According to a further embodiment, a safety switch is provided on the control unit, by means of which, when actuated, an automatic method, the sack truck can be triggered in a safety state. The safety state includes, for example, a defined inclination position, a reduced defined driving speed, the reduction of the current driving speed by a certain amount or a stopping of the driving movement, electronic or optical signals or a combination thereof. This can be reacted quickly if unforeseen situations occur, for example, the goods to be transported slip or get into the transport path obstacles. The safety can be increased with it. According to one embodiment, a separate drive motor is provided for each wheel. This makes it possible to dispense with a transmission for driving the individual wheels. Furthermore, a quiet driving operation and a high driving dynamics can be realized with low maintenance. The drive motors are provided, for example, as hub motors in the wheels, so that they can be arranged to save space.

According to a further embodiment, a proximity sensor is provided on the sack truck, by means of which an approach to an obstacle can be detected. As a result, obstacles can be detected. Stopping the hand truck can then be carried out by means of the proximity sensor and the control of the electric drive, without requiring any intervention by the operator. This is particularly advantageous when narrow maneuvering, the operator areas of the transport path can see poorly. Collisions and damage to the cargo as well as objects in the vicinity of the transport route can be minimized.

Developing the sack truck may have a load bearing, the load bearing preferably has an electrical height adjustment. The electric height adjustment allows you to adjust the height of the load bearing to the size and load bearing points of the load, without the operator having to manually raise or lower the load pickup. Preferably, a lifting and also a lowering of the load bearing are also possible when a load is on the load suspension. The electric height adjustment relieves the operator during the use of the sack truck, as this no longer has to lift the load manually. It is also possible to lift loads that are for example on a pedestal and then set down at ground level without the operator having to manually raise or lower the load. Consequently, the sack truck is very versatile.

A preferred embodiment of the sack truck provides that the electric height adjustment has a height selector switch, a height control and at least one stroke sensor, wherein the load receiving is designed so that the load receiving can be raised and lowered, the position of the load receiving detected by at least one stroke sensor and preferably shown on a display means. By operating the height selector switch, the operator can lift or lower the load suspension until it is at the required height. Alternatively, it is also conceivable that the operator selects a preset height or predetermined height. The height control raises or steers the load suspension until the sensor reports back to the height control to reach the selected altitude. An indicator can be used to display the current height of the load and the height selected to the operator. The display means may be, for example, a screen or an array of LEDs, one of which lights up when a certain position is reached. The ability to select a preset height or predetermined height, in which then the load is lifted or lowered by the height control, makes it easier for the operator to handle the sack truck. This is especially the case when work steps are repeated several times.

The height selection switch may be formed as a toggle switch, which moves in a switching position, the load-bearing up and in another down. Alternatively, two separate height selector switch are conceivable, a switch which moves the load bearing up and another switch, which moves the load bearing down.

According to one embodiment, the load bearing may have at least one hook. The at least one hook is formed and arranged on the load receiver, that a load can be hung on this or the hooks at least one hook on the load in a designated engagement position in the load and thus receives the load. To do this, the hook protrudes over the frame. In a preferred embodiment of the load-carrying device, it can have a plurality of the at least one hook. As a result, the load can be absorbed by the sack truck at different heights. In order to attach a plurality of the at least one hook on the load receiving at different heights, the plurality of at least one hook are laterally offset and pivotally arranged around the load receiving around. In this way, the at least one hook can be selected by the operator and brought into engagement with the load, which lies at a suitable height to the load.

According to a further embodiment of the sack truck, the load receiver may have a support means, wherein the support means (5) may be foldable. By a support means, the sack truck can take a load by the load is deposited on the support means or the load is lifted from below. Under a retractable support means such support means are to be understood, which can be folded over a joint so that they lie flat in the folded state on the frame of the sack truck. Thus, it is possible that the load bearing in addition to the support means may also have at least one hook to Attach loads to it. As a result, the possibility of using the sack truck is considerably expanded.

The method according to the invention for controlling a sack truck has at least the following method steps:

a) retrieving a stored in the control of the electric drive target inclination position or enter a desired target inclination position of the sack truck by means of the control panel,

b) detecting the inclination position of the sack truck by means of the inclination sensor, c) controlling the electric drive so that the desired inclination position is achieved by a method of sack truck.

The operator is relieved of balancing the sack truck with physical force, which places a great burden on the operator in conventional sack trucks. This allows the operator to concentrate his concentration and power on the exact process of the sack truck. The sack truck can thus be moved more accurately, even in confined space situations. Further, it is no longer necessary for the operator to brace himself against the sack truck to balance this or procedures. The position of the operator relative to the sack truck is thereby made more flexible, which simplifies the procedure in confined spaces. The sack truck can be moved through a manually set by the operator speed or it is recalled a stored speed in the controller.

Developing further, the method is designed so that the sack truck holds itself in balance near a desired position. The sack truck makes small back and forth movements around the position to balance the sack truck. The center of gravity of the sack truck is held above the line formed by the two points of contact of the wheels with the ground that cuts in the center of gravity of the sack truck weight vector of the sack truck cuts the straight line.

This allows the sack truck to be parked with the cargo at a selected position. This is advantageous if the transport route is not free or should be maintained for further logistical reasons with the onward transport.

Further, the method for controlling the sack truck is designed so that the controller can be added via a selector switch during operation in different operating modes. The operating modes may include, but are not limited to, a manual drive mode, a motorized drive mode, and a motorized, stabilized drive mode. As the operator of the sack truck It is useful if the operator can select in which operating mode the sack truck is to be operated, if it is often faster and more accurate to execute certain movements manually than is the case with a solely electric-powered sack truck. This allows the operator to select the operating mode as required, thereby transporting the loads faster.

Conveniently, the method is configured such that a travel speed of the sack truck when falling below a minimum distance, for example, of 100 cm, is reduced to an obstacle detected by the proximity sensor. The operator is given more time by the reduced speed to reverse the obstacle. The probability of a collision can thereby be reduced. Furthermore, the sack truck is thus easier to use and reduces the stress on handling the sack truck for the operator.

In a further development, the method is configured in such a way that the picking up of the load by the method steps: a) switching to the motorized drive mode, if the motorized, stabilizing drive mode was previously set,

b) Manual forward tilting of the hand truck in the vertical position,

c) moving the sack truck to the load until contact with the load,

d) producing the engagement of the load bearing with the load,

e) lifting the load by the electrical height adjustment of the load suspension, f) manually tilting the sack truck backwards until the loaded sack truck is in equilibrium,

g) change to the motorized, stabilized drive mode,

h) method of sack truck and load to the destination is achieved.

In addition, it is expedient if the method is designed such that the settling of the load by the method steps: a) approaching the loaded sack truck close up to the setting position, b) change to the motorized drive mode, if previously set the motorized, stabilized drive mode was

c) Manual forward tilting of the loaded sack truck into the vertical position,

d) lowering the load by the electrical height adjustment of the load bearing, e) releasing the engagement of the load bearing with the load, Manually tilting the sack truck backwards until the unloaded sackka is in balance

(Optional) change to the motorized, stabilized drive mode,

Method of sack truck (1) is achieved.

For an economical use of the sack truck, it is important that the operator can decide for himself when the sack truck is in which operating mode. This is particularly the case in the last few centimeters close to the pickup position or the drop position since the operator is often able to operate the bag cart more sensitively and faster than is possible in a motorized, stabilized drive mode.

The invention will be further elucidated on the basis of exemplary embodiments with reference to the enclosed figures of the drawings.

It shows schematically:

Fig. 1: a sack truck according to a first embodiment in a perspective view;

Fig. 2: the sack truck according to the first embodiment in a

Side view;

3 shows a functional diagram of a hand truck according to a second

Embodiment;

Fig. 4 shows a sack truck according to a second exemplary embodiment in a perspective representation

Fig. : 5 a sack truck according to the second embodiment in a

Top view;

6a is an enlarged detail of a section through a sack truck according to the second embodiment;

Fig. : 6b enlarged section of a sack truck according to the second

Embodiment in a plan view; Fig. 7 a cornering of a sack truck according to the second embodiment in a plan view in a forward drive;

Fig. 7b cornering a sack truck according to the second

Embodiment in a plan view in a reverse drive;

Fig. 8 is a functional diagram of the electrical height adjustment;

Fig. 9a-9e are flow diagrams of the method for picking up a load; and FIGS. 10a-10e are flow diagrams of the method for depositing a load.

In the figures, the same reference numerals designate the same or functionally identical components, unless indicated otherwise.

Fig. 1 shows a sack truck 1 according to a first embodiment in a perspective view. The sack truck 1 has a frame 3, which is partially formed in this embodiment of aluminum profile elements. On the frame 3 a in this embodiment, a scoop-like trained support means 5 is arranged for receiving transport goods. The support means 5 is arranged vertically adjustable on the frame 3 in this embodiment. On the frame 3 drive wheels 7a, 7b are further provided for moving the sack truck. The drive wheels 7a, 7b are arranged coaxially with each other. An electric drive 9 is provided for driving the drive wheels 7a, 7b. The electric drive 9 has in this embodiment, two electric motors 1 1 a, 1 1 b, each driving one of the drive wheels 7a, 7b, whereby a gear differential can be omitted. The electric drive 9 also has a controller 13 which controls the electric motors 1 1 a, 1 b. The controller 13 receives operator inputs from an operator through a control panel 15, which is removably mounted to the frame 3 in this embodiment.

Fig. 2 shows the sack truck 1 according to the first embodiment in a side view. The right wheel 7b faces the viewer, the left wheel 7a is located in the image plane behind it and therefore is not visible in this view. The wheels 7a, 7b are on a substrate 17. A straight line 19 passes through the contact points of the wheels 7a, 7b with the substrate 1 7 and is marked in this view as a point, since it extends into the image plane. An inclination position 21 relative to the ground 17 of the sack truck 1 is shown as a bow. It thus corresponds to the angle of inclination of the sack truck 1 relative to the substrate. 7 Fig. 3 shows a functional diagram of the sack truck 1 according to a second embodiment example. The functional diagram shows in particular how individual components of the sack truck 1 can interact.

The control panel 15 sends information to the controller 13. At the same time, the controller 13 receives a signal from a remote control key 23, which enables a transition from a stand-by operation to a drive operation mode.

The controller 13 executes a start sequence in which the controller 13 checks whether it is locked, whether a tilt sensor 25 is calibrated to zero degree, whether the voltage of a battery 27 is sufficient and whether an additional module has been installed via a module switch 29.

After the start sequence and when all queries are positive, the sack truck 1 is ready to be driven by the interface of the control panel 15.

On the control panel 15, a combined forward / reverse control lever 31 a, 31 b are provided in this embodiment for each drive wheel 7a, 7b. Furthermore, a pivoting action control lever 33 is provided so that the sack truck can be locked in a user-defined pivoting position angle. Furthermore, a safety switch 35 is arranged on the operating part 15. In addition, two switches 37, 39 are provided for operating add-on modules when the module switch 29 is activated.

When the switches 31 a, 31 b are operated, the sack truck 1 moves forward or backward. When only the switch 31 a is operated, the controller 13 sends signals only to the left electric motor 1 1 a, and when only the switch 31 b is operated, signals are sent only to activate the right electric motor 1 1 b.

When the switches 31 a, 31 b are positioned in a forward position, the sack truck 1 is moved forward at a speed which is defined by the pressure on the switches 31 a, 31 b. An acceleration sensor 41 controls the maximum speed to a desired value.

During forward travel, a proximity sensor 43 is active. If obstacles occur at a definable distance, in this embodiment 100 cm or less, the proximity sensor 43 gives a signal to the controller 13 to reduce the vehicle speed to a predetermined value. To load the sack truck 1, the sack truck 1 is moved with the support means 5 under the cargo. On the control panel 15 then the safety switch 35 is actuated, whereby the support means 5 is raised and the sack truck 1 is pivoted to a rear pivot angle of 35 ° or more. When the desired tilt angle is achieved, the tilt sensor 25 takes control so that the required angle is maintained constant by sending signals to the controller 13 and the controller 13 then sends signals to the electric motors 11a, 11b to maintain the position.

To unload the sack truck 1, the operator operates the controller 13 to maintain the desired swivel angle and advances the sack truck 1 in a slow and controlled motion. When the inclination sensor 25 detects an inclination angle of, for example, 0 degrees, it becomes possible to move the sack truck 1 backwards and to unload by operating the switches 31a, 31b.

Figure 4 shows a perspective view of a second embodiment of the invention of the hand truck 1 with electric drive, as it is used in particular for the breweries. The sack truck 1 consists of a frame 3, at the lower end of the side two drive wheels 7a and 7b are mounted. The wheels are driven by electric motors, of which the left electric motor 1 1 a is shown visible. This sack truck 1 also has a controller 13 which controls the electric motors. The sack truck 1 is operated by two operating parts 15, which are each positioned on each of the two handles 45 so that the operator can operate the operating part ergonomically while gripping the sack truck on the holding element 45. The second embodiment of the sack truck according to the invention further comprises a load receiver 48, in which the electric height adjustment 49 is positioned vertically in the middle of the frame 3. The electric height adjustment has in the illustrated embodiment at its lower end to a lifting motor 57, which can raise or lower the electric height adjustment 49. Furthermore, the electric height adjustment 49 has six hooks 54 distributed over the length of the electric height adjustment 49. The hooks 54 are divided into two groups, each consisting of three hooks 54 arranged one above the other. The two groups of hooks 54 are rotated relative to one another and offset in height, arranged around the electrical height adjustment 49 on the load receiver 48. By turning the electric height adjustment about its longitudinal axis so the sack truck 1 can engage loads at different heights. FIG. 5 shows a plan view of the second embodiment of the hand truck 1 according to the invention, as already shown in FIG. A load 55, which is a crate. Further, the two handles 45 are shown. Each of the handles 45 has a control panel 15, via which the functions of the sack truck 1 can be controlled. On the illustrated left control panel 15 of the forward / reverse control lever 31 a is shown, via which the direction of rotation and the speed of the drive wheel 7a can be controlled. Furthermore, the control unit 15 has two height selection switches 50, via which the lifting motor 57 of the electric height adjustment 49 can be controlled in its function. By means of the two height selection switches 50, the load 55 can be raised or lowered with the aid of the load receiver 48.

The right of the two illustrated operating parts 15 has a forward / reverse control lever 31 b, via which the direction of rotation and rotational speed of the right drive wheel 7b can be controlled. Via the selector switch 44, the operating mode of the sack truck 1 can be selected from manual drive mode via the motorized drive mode to the motorized, stabilized drive mode. Furthermore, both of the illustrated handles 45 have two lateral, oppositely disposed steering sensors, with which the controller 13 and the control built therein can measure an intended cornering of the user, so that it is performed by the controller 13.

FIG. 6 shows a longitudinal section through the electrical height adjustment 49, as used in the second exemplary embodiment. Evident are two of the hooks 54, which protrude beyond the frame 3 also, so that a load, which is located in front of the frame 3, can be attached to this. Recognizable in the background is the electric motor 1 1 a of the left drive wheel 7a.

FIG. 6b is an enlarged detail of the plan view shown in FIG. 5 of the second embodiment of the hand truck 1 according to the invention. To recognize the mounted on the frame 3 load receptacle 48 can be seen. This is composed of the electric height adjustment 49, the hook 54 and the lifting motor 57 together. Evident are two of the laterally twisted on the electric height adjustment 49 arranged hooks 54. One of the two hooks 54 protrudes beyond the frame 3, so that a load can be attached to this. By a rotation of the electric height adjustment 49 counterclockwise, the other of the two hooks 54 shown can be brought into a position so that this after protrudes forward over the frame 3. As a result, loads can be recorded in different heights.

FIG. 7 a shows a plan view of a forward-driven curve of the second exemplary embodiment of the hand truck 1 according to the invention. The cornering is initiated by a steering movement 47, which applies the operator of the sack truck 1 on the handles 45. The steering movement is detected by steering sensors 46, which are attached laterally to the handles 54.

The signals of the steering sensors 46 are processed in the controller 13. The control here controls that the inside of the drive wheel 7b slower and the outside drive wheel 7a rotates faster. This can be seen at the different length of the lanes 56 of the inside drive wheel 7b and it outside the drive wheel 7a. From the different rotational speeds of the drive wheels 7a and 7b results in cornering of the sack truck. 1

Figure 7b is a plan view of a reverse driven curve of the second embodiment of a sack truck. 1 As already described in FIG. 7 a, a steering movement 47 is applied to the handles 45 by the operator. Incidentally, the cornering is analogous to the procedure described under Figure 7a with the difference that the wheels rotate 7a and 7b not forward but backward.

FIG. 8 shows a functional diagram of the electric height adjustment 49, as it may have the hand truck 1 according to the invention. The function diagram shows in particular how the individual components of the electric height adjustment interact. About the height selector switch 50, the input of the operator that the electric height adjustment 49 is to be opened or lowered. This signal is processed in the height control 51. The power supply of the height control and the components connected to it via the battery 27th

Depending on the choice of the user, whether the electric height adjustment 49 is to be opened or lowered, there is a corresponding circuit of the lifting motor 57, which raises or lowers the load receiver 48.

In order for the user to receive feedback about the lifting height, four lifting sensors 52 are connected to the upper control 51, which report the reaching of a specific lifting position to the height control 51. It is conceivable that a stroke sensor 52 is in the lowest stroke position, another stroke sensor 52 in the highest stroke position and two further stroke sensors 52 are located between the highest and the lowest stroke sensor 52. The detected stroke position is displayed by the stroke control 51 via a display 53 to the operator. The display 53 may, for example, consist of four LEDs which each light up when a stroke position of a stroke sensor 52 is reached.

FIGS. 9a to 9e schematically show the method for picking up a load 55 through the bagcart. In Figure 9a, the operator is shown with a sack truck 1 without load. The operator approaches in Figure 9b with the unloaded sack truck 1 to the load 55, where he, if not yet, changes from the motorized, stabilized drive mode in the motorized drive mode. At the same time he tilts the sack truck 1 in a vertical position. Then he drives the sack truck 1 as shown in Figure 9c, until the sack truck 1 has contact with the load 55. The operator engages the load bearing with the load. Subsequently, the operator raises the load 55 by means of the electrical height adjustment of the load receiving device. FIG. 9e shows how, by manually tilting back the loaded sack truck, it is brought into an equilibrium position and simultaneously removed about 20-30 cm from the receiving position or from an obstacle. In this position, the operator can switch back to the motorized, stabilized drive mode, so that the loaded sack truck stands upright on its own. Subsequently, the operator can move the sack truck to the desired destination.

FIGS. 10a to 10e describe the settling of a load 55 with the aid of the sack truck 1. FIG. 10 a shows how the loaded sack truck is moved up to the set-down position about 20-30 cm. If not already done, the operator will switch back from the motorized, stabilized drive mode to the motorized drive mode. Subsequently, as shown in FIG. 10d, the operator approaches the set-down position and brings the hand truck 1 into a vertical position by manually tipping the loaded hand truck forward. By actuating the electrical height adjustment, the load 55 is lowered and set down in the set-down position, as shown in FIG. 10c. Subsequently, the operator releases the engagement of the load bearing with the load and, as shown in FIG. 10 d, moves the sack truck back from the load 55. Finally, FIG. 10e shows how the operator moves the unloaded hand truck 1 backwards by manual tilting back into equilibrium and about 20-30 cm away from the load. Optionally, the operator can now switch to the motorized, stabilized drive, so that the unloaded sack truck remains standing upright. Reference number:

1 sack truck

3 frames

5 support means

7a, 7b drive wheels

9 electric drive

1 1 a, 1 1 b electric motors

13 control

15 control panel

17 underground

19 Straight

21 tilt position

23 remote control key

25 inclination sensor

27 battery

29 module switch

31 a, 31 b Forward / reverse control lever

33 Pivot action control lever

35 safety switches

37, 39 Switch for additional modules

41 acceleration sensor

3 proximity sensor

44 selector switch

5 handle

6 steering sensor

47 steering movement

8 load suspension

9 electric height adjustment

50 height selector switch

51 height control

52 stroke sensor

53 display means

54 hooks

5 load

56 driveway

7 lifting motor

Claims

claims

1 . Hand truck (1) with an electric drive (9) for driving at least two coaxially arranged drive wheels (7a, 7b) of the hand truck (1), with a control unit (1 5) and a control unit (1 3) for controlling the electric drive (9 ), characterized,

a tilt sensor (25) for determining a tilt position of

Sack cart (1) is provided, wherein the controller (1 3) is arranged so that they the sack truck on the electric drive (9) in a desired

Inclination, holds.

2. Hand truck according to claim 1,

characterized,

the controller (13) can be put into different operating modes during operation by means of a selector switch (44),

wherein the operating modes include, among others, a manual drive mode and a motorized drive mode.

3. sack truck according to claim 2,

characterized,

that the control (1 3) in motorized drive mode additionally in an operating mode m with motorized, stabilized drive can be placed, in which the control (1 3) via a control the sack truck (1) by the electric drive (9) near a desired position keeps itself in balance.

4. Hand truck according to one of the preceding claims,

characterized,

in that the operating part (15) has at least one handle (45), wherein the handle (45) can comprise at least one steering sensor (46), which has a

Steering movement (47) detected.

5. Hand truck according to one of the preceding claims,

characterized,

a separate control element (31 a, 31 b), in particular a control lever, is provided on the control unit (1 5) for each of the drive wheels (7 a, 7 b).

6. sack truck according to one of the preceding claims,

characterized, in that the operating part (15) is provided on the hand truck (1) such that it can be displaced relative to a frame (3) of the hand truck (1).

7. Hand truck according to one of the preceding claims,

characterized,

that the operating part (15) via a wireless, in particular a

Radio link, with the electric drive (9) is networked.

8. sack truck according to one of the preceding claims,

characterized,

that the operating part (15) is designed as a drawbar.

9. sack truck according to one of the preceding claims,

characterized,

in that a safety switch (35) is provided on the control unit (1 5), by means of which the sack truck (1) can be released into a safety state when actuated by an automatic method.

10. sack truck according to one of the preceding claims,

characterized,

a separate electric motor (11a, 11b) is provided for each drive wheel (7a, 7b).

1 1. Hand truck according to one of the preceding claims,

characterized,

in that a proximity sensor (43) is provided, with which an approach to an obstacle can be detected.

12. sack truck according to one of the preceding claims,

characterized,

the sack truck (1) has a load receiver (48), wherein the load receiver (48) preferably has an electrical height adjustment (49).

1 3. Hand truck according to one of the preceding claims,

characterized,

in that the electric height adjustment (49) has a height-selection switch (50), a height control (51) and at least one stroke sensor (52), wherein the load receiver (48) is designed such that the load receiver (48) can be raised and lowered, wherein the position of the load receiver (48) detected at least one stroke sensor (52) and preferably on one

Display means (53) shown.

14. sack truck according to one of the preceding claims,

characterized,

the load receiver (46) has at least one hook (54).

1 5. Hand truck according to one of the preceding claims,

characterized,

the load receiver (46) has a support means (5), wherein the

Pad (5) can be folded.

16. A method for controlling a sack truck (1) according to one of claims 1 to 15 with the method steps:

(A) retrieving a in the control (1 3) of the electric drive (9) stored target inclination position (21 ^' ) or enter a desired target inclination position (21 ^' ) of the sack truck (1) by means of the control unit (1 5);

(b) detecting the tilting position (21) of the sack truck (1) by means of the

Inclination sensor (25);

(C) controlling the electric drive (9) so that by a method of the sack truck (1) the target inclination position (21 ^' ) is achieved.

1 7. The method of claim 16,

characterized,

that the sack truck (1) keeps itself in balance near a desired position.

18. The method according to claim 16 or 1 7,

characterized,

the controller (13) can be put into different operating modes during operation by means of a selector switch (44).

1 9. The method according to any one of the preceding claims,

characterized,

that a driving speed of the sack truck (1) when falling below a minimum distance, in particular of 100 cm, to a by the

Proximity sensor (43) detected obstacle is reduced.

20. The method according to any one of the preceding claims

characterized,

that the picking up of the load (55) by the method steps:

(a) bringing the unloaded sack truck (1) to the load,

(b) change to the motorized drive mode when the motorized, stabilized drive mode was previously set,

(c) manually tilting the sack truck (1) forward to the vertical position,

(d) approaching the sack truck (1) to the load (55) up to m contact with the load (55),

(e) establishing the engagement of the load receiver (46) with the load (55),

(f) lifting the load by the electrical height adjustment of the load receiver (46),

(g) Manually tilting the sack truck (1) backwards until the loaded sack truck (1) is in equilibrium,

(h) change to the motorized, stabilized drive mode,

(i) moving the sack truck (1) and load (55) to the destination. 1 . Method according to one of the preceding claims,

characterized,

that the settling of the load (55) by the method steps:

(a) approaching the loaded sack truck (1) near to the set-down position,

(c) manually tilting the loaded sack truck (1) forward to the vertical position,

(D) lowering the load (55) by the electrical height adjustment of

Load bearing (46),

(e) releasing the engagement of the load receiver (46) with the load (55),

(f) Manually backward tilting the sack truck (1) until the unloaded

Sack cart (1) is in equilibrium,

(g) (Optional) change to the motorized, stabilize drive mode,

(h) method of sack truck (1) is achieved.