EP1122209A1 - Gripping device for a lift truck - Google Patents

Abstract

The gripper has two clamp arms of adjustable separation and length chosen for several payloads and a control circuit for setting/displaying the clamping force. A vertical pendulum axle is fitted in the center of at least one arm so the surface of the arm acting on the load can pivot about the axle. A limiter restricts the maximum pendulum angle. A switch outputs a signal to the control circuit depending on the angle limit being reached. The gripper has two clamp arms (1,2) of adjustable opening width whose length is chosen to enable engagement with several payloads (K) in series and/or adjacent to each other and a control circuit for setting and/or displaying the clamping force. An essentially vertical pendulum axle (9) is fitted in the center of at least one flat clamp arm so that the surface of the arm acting on the load can pivot about the pendulum axle. A limiter restricts the maximum pendulum angle and a switch (11,12) outputs a signal depending on the angle limit being reached to the control circuit.

Description

The invention relates to a gripper device for a lift truck in the form of a Stapler with two flat surfaces adjustable in their opening width Clamp arms or jaws, the length of which is essentially for gripping several to be taken one behind the other and / or next to each other Payloads is dimensioned and a control circuit for the adjustment and / or display of the clamp force are assigned. The gripper device can in particular be designed as a stapler.

With such attachments or gripper devices it is possible to certain Take up payloads between the clamp arms or jaws, by exerting a force to hold it in place and without bottom support by moving the loader to a desired location.

It has already been recognized in DE-PS 908 471 that during handling various high stacks of boxes of citrus or the like it makes sense to proportionally or at any rate the force exerted on the stack of boxes depending on the total mass or the total weight the stack of crates or other payload. Becomes one too exerted little pressure, the clamp arms can not stack the box hold; is a contact force that is too great for the current stack of boxes exercised, this affects an area of the payload that is too small, causing damage or destruction. The increase in contact pressure depends of the payload is also in EP 0 529 488 A1 by corresponding mechanical Constructions have been guaranteed.

However, such constructions have the disadvantage that they differ from current, For example, forces arising from the driving situation of the loader undesirable when driving over bumps or slopes react because these forces are also implemented by the constructions.

DE 38 01 133 C2 and DE deal with another problem EP 0 244 984 A2. Here, using photo sensors, such as light barriers, the loading depth of the lift truck is measured to ensure that the appropriate Payloads are also recorded correctly and completely. For example of several boxes in a row, only one or also several, but of course completely handled. These conceptions are quite complicated and prone to errors. Light barriers and Photodetectors can easily become dirty, especially in harsh environments then cause malfunction.

In contrast, the object of the invention is a gripper device for a Propose a loader with which in a technically simple and as little as possible error-prone form a reliable transport of several in particular cuboid payloads is possible.

This object is achieved in that a pendulum axis on at least one of the flat clamp arms is provided that this pendulum axis in middle region of the bracket arm is arranged and substantially perpendicular runs so that the surface of this clamp arm facing the payloads can swing about the pendulum axis, that a limiter is provided, the maximum pendulum angle of the surface facing the payloads the parallel to the opposite surface of the other bracket arm limited, and that a switch is provided, which is dependent on the achievement this maximum pendulum angle emits a signal that the control circuit for the setting and / or display of the clamp force is supplied.

Such a design surprisingly solves the problem, both extraordinarily reliable as well as technically quite simple and inexpensive.

In a different context, such swing axes are in the case of clamp arms for forklift trucks already known. If namely boxes with completely similar Products are available, there are nevertheless certain dimensions Fluctuations. The size of the boxes, for example for washing machines or refrigerators is usually not particularly critical and can therefore deviate from each other by a few millimeters.

If you try to clamp several of these boxes at the same time one of these boxes may be a little wider than that others, so that a pair of clamp arms can hold the larger of these boxes well could be the slightly smaller box but due to the slightly locked clamp arms could fall through or slip out. This can be avoided by one of the two clamp arms on one in the Is suspended substantially perpendicular pendulum axis and at Moving the two clamp arms of this pendulum suspended Bracket arm thus has the option of freely graduated if necessary Adapt the shape of the cardboard surfaces facing him. The bracket arm is therefore possibly slightly slanted. It's only about angles of a few Angular minutes or maybe a few degrees. Now stands this Bracket arm slightly inclined, so it holds both the larger and the slightly smaller box. The other bracket arm can be conventional stay educated.

This pendulum suspension, which is used and useful for a completely different purpose one of the clamp arms can now be used according to the invention to help solve the problem of interest. This swinging suspended bracket arm behaves in the complete absence of a carton so that it goes to a maximum position in this regard. He will namely limited by no payload and no carton in its pendulum movement and moves into the maximum stop inwards because of the clamp arm is not slowed down by a "small" box. This maximum stop too is of course only a few degrees from the parallel to the other Offset arm. The other side of the bracket arm that is swinging outwards still grips the existing box.

The switch provided according to the invention now gives, for example, when it is reached this maximum pendulum angle a signal that the control circuit for setting and / or displaying the clamp force is supplied. Reaching this maximum pendulum angle at the limiter implicitly shows the absence of a cardboard box, so that the control circuit now inferred from this Signal correctly set the clamp force or at least an appropriate one Can submit ad.

The clamping force can be optimally based on the number of boxes between the two Brackets can be matched.

The control circuit therefore has exact information about whether there is an or two payloads are in a row and can be the required Request the clamping force of the two clamp arms.

Instead of giving a signal when the maximum is reached, of course conversely, a signal is constantly given, which is switched off when reached different or depending on the angular position of the signal Signals are given.

Usually, between two bracket arms not only one after the other, but also one or more boxes can be picked up next to each other. However, the attachment can also do this without any additional Measure to see how far the two clamp arms have moved apart are. No additional switches are required for this.

It is also much easier to determine whether than in the prior art maybe several payloads on top of each other between the clamp arms are located. This is because it is also possible to have a further one, essentially horizontal running pendulum axis. This can either be on the other bracket arm be provided or on the same bracket arm with the cross first pendulum axis, so that a point suspension for power transmission is provided on the bracket arm, so a kind of universal joint arises.

If such a horizontal pendulum axis is now also provided, that they are roughly level with the top of a box below is located, can be determined immediately by a similar limiting function whether one or two boxes are on top of each other.

The control circuit can then combine the various signals evaluate directly to determine whether only one box, two boxes side by side, in a row or on top of each other, four boxes either in an area of twice two boxes or in two layers to two boxes on top of each other or there may even be eight boxes between the two clamp arms. For each of these cases, it can determine the optimal clamping force and use or at least indicate that such a clamping force is applied should be.

For example, there are a total of eight between two bracket arms Payloads, namely two superimposed layers of four square each arranged boxes, so this is done by the Attachment detected. The two switches on a bracket arm determine that they are not in their maximum position, so they are loaded with two boxes each are and the attachment also automatically detects that the two Bracket arms have exactly the distance that the Corresponds to the width of two boxes. The corresponding message to the signal processing and control unit results in that the clamping force of the clamp arms must be large enough to hold a total of eight boxes. At the same time but there is also a guarantee that the side surface of four Cartons for absorbing this corresponding clamping force and thus for distribution the resulting pressure is available, so that damage can be avoided.

On the other hand, there is only a single box between exactly the same Brackets, both switches will react accordingly, since the Bracket arm swivels to its maximum position around both pendulum axes; Right away in front of the lift loader, since there is no box there, and around the horizontal axis above inwards, since there is only one box below. The Switches therefore report the absence of the signal processing and control unit appropriate boxes.

The distance between the clamp arms corresponds to the width of a box, so that the Control unit provides enough clamping force for a box, which is also appropriate easily endured from the side wall of this one carton can be.

The same applies to all transportable interim solutions, for example for a single layer of four square boxes or for four payloads arranged in two rows one above the other. Any constellation can be recognized by the signal processing and control unit and accordingly be taken into account.

The driver of the lift loader does not have to do any switching operations, observation operations or take other measures to influence the force of the clamp arms. This, of course, also prevents possible incorrect operation.

The actual design of the switches can take various forms. The requirements for these switches are relatively simple. You just have to in the Be able to determine that the maximum value has been reached and either a switch that responds to a stop, a pressure switch, but of course also a suitable electronic located in the pendulum axis itself Switch is used, which detects that a certain rotation takes place is or has not just happened.

All of these switches are insensitive and inexpensive and also remain possible pollution that can occur in the harsh climate can work in the lift loader without any influence on the function.

Theoretically, a conception is also conceivable that more than two one above the other and / or capture cardboard boxes arranged one behind the other and / or next to one another can. To do this, three pendulum axles would have to be used for three cardboard boxes that can be picked up in succession are provided, which are then each achieved by reaching the maximum positions on one side or the other determine which relative occupations can be seen through the boxes between the bracket arms.

The presence of one, two or three could of course be similar Cardboard boxes arranged one above the other through several horizontal pendulum axes determine. Such conceptions would, however, only be expressed Special cases of interest.

The gripping device can be an integral part of the lift loader, preferably however, is their separate version as an attachment.

Figur 1

eine Draufsicht auf eine schematische Darstellung eines erfindungsgemäßen Anbaugerätes;

Figur 2

eine Draufsicht auf das Anbaugerät aus Figur 1 bei einer anderen Beladung;

Figur 3

eine Draufsicht auf das Anbaugerät aus Figur 1 bei einer dritten Beladung;

Figur 4

eine Draufsicht auf das Anbaugerät aus Figur 1 bei einer vierten Beladung; und

Figur 5

eine schematische Darstellung eines Schaltbildes für die Gesamtkonzeption.

An exemplary embodiment of the invention is explained in more detail below with reference to the drawings. Show it:

Figure 1

a plan view of a schematic representation of an attachment according to the invention;

Figure 2

a plan view of the attachment of Figure 1 with another load;

Figure 3

a plan view of the attachment of Figure 1 with a third load;

Figure 4

a plan view of the attachment of Figure 1 with a fourth load; and

Figure 5

a schematic representation of a circuit diagram for the overall concept.

A preferred embodiment of the invention can be seen from above in FIG. 1 . On the left in the picture you have to imagine the lift loader or forklift. The attachment, which is only shown schematically, is fastened to this, which can be moved up and down as usual, for example to remove boxes with washing machines from a high rack.

The attachment consists of various components that coordinate this movement and which are not shown in the figures, but furthermore in particular from two bracket arms 1 and 2. These bracket arms are jaws that vertically oriented clamping surfaces for contacting the payload to be transported, for example, the boxes K have. These bracket arms 1 and 2 can against each other and away from each other. This is shown in FIG. 1 indicated that a position is shown in which the clamp arms 1 and 2 are arranged relatively close to each other.

In a second position it is shown in FIG. 2 that the clamp arms are spaced sufficiently far apart to accommodate two boxes K with payloads placed next to one another. In the first position in FIG. 1, exactly one carton K fits between the two clamp arms 1 and 2.

Two switching elements 7 and 8 are provided, which the current position of the Grab the clamp arms. Since a particular attachment is usually only for Transport of a very specific type of box of predetermined size is provided, of which even a very specific number of either one or two Pieces can be added side by side between the clamp arms 1 and 2 should, the switching elements 7 and 8 only by specifying a "Yes" - and a "No" statement to clarify whether there is a box or two between the clamp arms 1 and 2 can be. Of course it is also possible directly from the movement control of the clamp arms 1 and 2 this Tap data.

The clamp arms 1 and 2, i.e. the jaws with their in a vertical Flat clamping surfaces protrude from the base by about a depth of two boxes far into the room. In this way, the clamping surfaces also be pressed exactly against the side walls of the boxes K, if one or two of them are oriented one behind the other. This applies to both Bracket arms 1 and 2.

Only on one of these clamp arms, namely that of the driver of the forklift from the right on the right in Figure 1 arranged bracket arm 2 is a Pendulum axis 9 is provided. The bracket arm 2 with its the boxes K with the Payload inner surface can swing around this pendulum axis 9. The pendulum axis 9 itself is mounted on a support structure 10 that in turn performs the aforementioned displacement movements.

As can be seen in Figures 1 and 2, there are only in the front, from Areas facing away from the loader between the clasp arms K, namely in Figure 1 a box and in Figure 2 two boxes. In the In contrast, the loader adjacent areas is not a payload. This leads to the area of the clamp arm 2 facing away from the lift loader when the clamp arms 1 and 2 are moved together by the cartons K. the area adjacent to the loader is not. Consequently the bracket arm 2 rotates clockwise about the pendulum axis 9 in FIG. 2, until it reaches a maximum value. Another spin in this Direction is prevented by a limiter, not shown. This delimiter can be a mechanical lock of the simplest type.

In the figure shown, the outermost end of the loader facing the Clamp arm 2 equipped with a switching flag 11. This switch flag 11, the can also be seen in Figure 1, is located in both figures on their furthest inward position. It is thus separated and not in contact with a switching element 12, which is located in the base region of the supporting structure 10 is located, that is, where the support structure 10 the bracket arm 2 with the Basis connects. The switching flag 11 forms together with the switching element 12 a switch.

FIG. 3 now shows a situation in which the clamp arms 1 and 2 enclose two cartons K with payload arranged one behind the other. Similar to FIG. 1, the switches 7 and 8 for determining the opening width are consequently in position relative to one another in such a way that they determine that only one box K can be located next to one another in the two clamp arms 1 and 2.

On the other hand, the surface of the bracket arm 2, which the cartons K faces the entire payload. This uniform application of the surface of the clamp arm 2 now leads to that the bracket arm 2 both in front of and behind the pendulum axis 9 with forces is acted on, so that the clamp arm 2 is not in itself Maximum position, but in a balanced position, from one Average value only due to slight dimensional fluctuations or tolerances of the cardboard boxes K differ.

Compared to the situation in FIG. 1, this means that the switching lug 11 turns moved outward counterclockwise (compared to Figure 1) and thereby comes into contact with the switching element 12. The contact provides the Switches 11, 12 are fixed and emits a corresponding signal.

FIG. 4 shows a representation similar to FIG. 2. Here, the switches 7 and 8 determine that two boxes K arranged next to one another with a payload are located between the clamp arms 1 and 2. Similar to FIG. 3, on the other hand, the clamp arm 2 on the support frame 10 is again loaded with payloads by boxes K both in front of and behind the pendulum axis 9, so that the switching lug 11 comes into contact with the switching element 12 here as well.

From a representation of the corresponding pendulum movements an approximately horizontal pendulum axis is not shown here. This can alternatively or be provided in addition.

The total of four switches or switching elements 7, 8, 11, 12 are capable specify exactly how many boxes K with payload are in which configuration are between the clamp arms 1 and 2. For example, there are none Switch operated, so it can easily be concluded that obvious there are no boxes K in the rear area adjacent to the lift truck, So only boxes in the front area between the clamp arms 1 and 2 are located.

In addition, switches 7 and 8 can still be closed from inactivity that the clamp arms 1 and 2 have not moved together, that is have picked up two boxes next to each other. So are exactly two boxes between the clamp arms 1 and 2, namely in front area. This corresponds to the situation from FIG. 2.

In another example, the switching elements 11 and 12 are actuated, for example can be concluded with similar considerations that a total of four Cardboard boxes arranged in a square on the lower level between the clamp arms 1 and 2 are located.

In practice, the drivers of lift loaders always only take individual boxes K at the front between the clamp arms 1 and 2, i.e. in the forklift even the most distant and distant area. This has practical reasons, so the clamp arm does not have to be in behind the box for the area that is difficult to see for the driver. This behavior allows only one extreme position to be provided, namely the non-existence a payload adjacent to the loader. But it would also be possible also another switch arrangement for reaching another Extreme values in the absence of a payload on exactly the other, namely the to be provided away from the forklift, because the clamp arm its pendulum axis would then behave accordingly. The Signal processing and control unit 18 would then of course still be appropriate additional signals to be taken into account.

Figure 5 shows schematically the control of such an arrangement. In the lower half of FIG. 5, a representation similar to FIG. 4 can be seen rotated through 90 ° and mirrored. The switching elements 7, 8, 11 and 12 can be seen here. Two lines each go from two switch groups to a signal processing and control unit 18, to which a total of two pieces of information are supplied. A voltage supply 13 makes it possible to determine this simply by applying voltage to corresponding switches, but of course another construction is also conceivable.

The figure below also shows two hydraulic cylinders 23 and 24, with which the clamp arms 1 and 2 are moved apart and moved together can, these two hydraulic cylinders also the clamping force with which the jaws or clamp arms 1 and 2 with their clamping surfaces on the boxes K arranged between them with the Work payload.

The control area is indicated purely schematically in the upper half. At the top left is the forklift hydraulic system 15, which is the basic one Functions. This actuates the hydraulic valve 15 for the clamp and Sideshift function. The hydraulic valve 16 actuates, as already discussed, the Hydraulic cylinders 23 and 24 in conventional form.

Processed by the signal processing and control unit 18 Data of the switching elements 7, 8, 11 and 12 fed to a multi-stage pressure valve 17, which then calculates the required pressures from this data determined and with these data, the hydraulic valve 16 for the clamp and sideshift function is applied. This will be next to the movements of the clamp arms 1 and 2 desired by the driver now additionally from the hydraulic cylinders 23 and 24 also the required clamping forces taken into account, depending on the number and arrangement of the boxes K with the Payloads are.

Reference list

1

Bracket arm

2nd

Bracket arm

7

Switching element for determining the opening width

8th

Switching element for determining the opening width

9

Swing axle

10th

Shoring

11

Switch flag

12th

Switching element

13

Power supply

15

Forklift hydraulics

16

Hydraulic valve for clamp and sideshift function

17th

Multi-stage pressure valve

18th

Signal processing and control unit

23

Hydraulic cylinder

24th

Hydraulic cylinder

K

Cardboard box with payload

Claims (9)

Gripper device for a lift truck with two flat clamp arms (1, 2) adjustable in their opening width, the length of which is essentially dimensioned for gripping a plurality of payloads to be gripped one behind the other and / or a plurality of juxtaposed payloads and for which a control circuit for setting and / or display are assigned to the clamp force,
characterized, that a pendulum axis (9) is provided on at least one of the flat clamp arms (2), that this pendulum axis (9) is arranged in the central region of the clamp arm (2) and extends essentially perpendicularly, so that the surface of this clamp arm (2) facing the payloads (K) can oscillate around the pendulum axis (9), that a limiter is provided which limits the maximum pendulum angle of the surface facing the payloads (K) from the parallel to the opposite surface of the other bracket arm (1), that a switch (11, 12) is provided which, depending on the reaching of this maximum pendulum angle, emits a signal that the control circuit (18) is supplied for setting and / or displaying the clamp force. Gripper device according to claim 1,
characterized,
that a second pendulum axis is provided, which is arranged in the central region of the same clamp arm (2) or the other clamp arm (1) and extends essentially horizontally, so that the surface of this clamp arm facing the payloads (K) can oscillate about the pendulum axis. Gripper device according to claim 1 or 2,
characterized,
that the clamp arms (1, 2) are designed so that two payloads (K) could be gripped one behind the other, side by side and one above the other. Gripper device according to one of the preceding claims,
characterized,
that a switch element (11) is arranged on the side of the clamp arm (2) adjacent to the lifting loader with the pendulum axis (9) and interacts with a further switch element (12) which is also arranged on a support frame (10) for the pendulum axis (9) is. Gripper device according to one of the preceding claims,
characterized,
that the switch element (11) has a switching flag, and that the further switch element (12) reacts to contact by the switching flag (11). Gripper device according to one of the preceding claims,
characterized,
that the pendulum axis (9) is arranged essentially in the center of the surface of the clamp arm (2) facing the payloads (K). Gripper device according to one of the preceding claims,
characterized,
that the device for detecting the lateral adjustment of the clamp arms (1, 2) has switch elements (7, 8) assigned to one or both clamp arms (1, 2), the position of which is selected such that it has one for gripping two payloads arranged next to one another (K ) Detect the required distance between the clamp arms (1, 2). Gripper device according to one of the preceding claims,
characterized,
that the measurement data of the switches (7, 8, 11, 12) are fed to a signal processing and control unit (18) and are converted into corresponding clamping forces by the latter. Gripper device according to one of the preceding claims,
characterized,
that the data of the signal processing and control unit (18) are fed to a multi-stage pressure valve, the output data of which are fed to the hydraulic valve (16) for the clamp function.

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