forklift truck with a load wheel lift

Abstract

Industrial truck with a drive unit and a load unit, which has a load wheel lift, which has a deflection lever, a kinematic rod, and a load wheel lever with at least one load wheel for each load arm (fork tine), wherein the deflection lever is designed as a three-point lever, of which a first lever point is mounted on the load unit, a second lever point is connected to the kinematic rod, and a third lever point interacts with a lifting device, wherein the third lever point has a contact element that is movably mounted along a cam track.

Description

[0001] The present invention relates to an industrial truck with a load wheel lift. The industrial truck has a drive section and a load section, the height of which is adjustable via the load wheel lift. The load wheel lift comprises a deflection lever, a kinematic rod, and a load wheel lever with at least one load wheel for each load arm. The deflection lever is designed as a three-point lever, with a first fulcrum mounted on the drive section, a second fulcrum connected to the kinematic rod, and a third fulcrum interacting with a lifting device.

[0002] EP 3 718 854 B1 discloses a transport device with a load wheel lift. The load wheel lift has a guide rod arranged vertically in the drive part, along which a load arm can be raised and lowered. The load arm has a deflection lever, the first fulcrum of which is connected to the drive part via a rod, the second fulcrum is connected to a kinematic rod for pivoting the load wheel lever, and the third fulcrum is connected to the height-adjustable load arm. Furthermore, the known load wheel lift has at least one support roller at a free end of the load arm, with which the load arm can be placed on a pallet board arranged transversely to the direction of entry. To use the support roller, the load wheel is pivoted into a position in which the load wheel no longer has contact with the ground, but rather the support wheel supports the load arm.Driving into a pallet initially takes place with the support wheel raised, so that it initially acts as a climbing aid and does not rest on the pallet board. The actual driving movement on the pallet board and between the pallet boards takes place after lowering by the support wheel and a load wheel that is folded out again and rolls safely on the ground. A disadvantage of the conventional load wheel lift has been found to be that when driving in and out of the pallet, you have to switch between the load wheel and the support wheel, and during this process it is not guaranteed that the load arm is always moved horizontally. A tilted load arm can occur, particularly in situations where the support wheel rests on a pallet board and the load wheel is raised further by lowering the load arm base.

[0003] EP 1 690 823 A2 discloses an industrial truck with a non-liftable drive section and a load section that is vertically guided and liftable on the drive section, comprising a load frame supported by load rollers. A lifting device lifts the load section relative to the drive section. The lifting device has a lever arrangement and a linkage that connects a part of the lifting device arranged in the drive section to the load rollers arranged on the load frame. The lever arrangement is designed as a deflection lever, which rests with a roller on a straight, inclined lifting track on a vertical frame section of the drive section.

[0004] The invention is based on the object of providing an industrial truck with a load wheel lift that ensures a horizontal movement of the load arm during lifting and lowering.

[0005] According to the invention, the object is achieved by an industrial truck having the features of claim 1. Advantageous embodiments form the subject matter of the subclaims.

[0006] The industrial truck according to the invention has a drive section and a load section. The load section is equipped with a load wheel lift, which has a deflection lever, a kinematic rod, and a load wheel lever with at least one load wheel for each load arm. The deflection lever is designed to convert the raising and lowering of the load arm into a movement of the load wheel lever with the at least one load wheel. The deflection lever is designed as a three-point lever with a first fulcrum mounted on the drive section. A second fulcrum is connected to the kinematic rod, and a third fulcrum interacts with a lifting device of the industrial truck.

[0007] According to the invention, the first fulcrum comprises a contact element that is movably mounted along a curved path. The first fulcrum is mounted on the drive part, wherein the movement of the contact element along the curved path causes the first fulcrum to move relative to the drive part and the load part. In the solution according to the invention, the first fulcrum moves along the curved path, making it possible to convert a lifting movement into a pivoting movement of the load wheel lever. If the first fulcrum were fixedly provided on the drive part or pivotably mounted on the drive part via a rod, the conversion of the lifting movement into the pivoting movement of the load wheel lever would remain essentially the same.A curved track makes it possible to change the position of the first fulcrum depending on the lifting height, thus better coordinating the movement between the load arm root and tip and preventing tilt of the load arm. In addition to the horizontal position that can be achieved during the lifting movement, the load wheel stroke can also be specifically controlled, for example, to achieve a specifically controlled load wheel stroke, particularly a defined tilt position, in selected lifting ranges.

[0008] In a preferred embodiment, the curved track has a second curved section against which the contact element rests when the load wheel folds without ground contact to reach its folded state. The second curved section serves to hold the load wheel, which has been folded without ground contact, in its folded state against the effect of gravity. The contact element rests or can rest against the second curved section when the load wheel is floating and has no ground contact.

[0009] Further preferably, the curved track has a first curved section against which the contact element rests when the load wheel makes contact with the ground via the load wheel lever and, for example, raises the load arm. The first curved section also interacts with the contact element when a movement or loading direction of the load wheel stroke changes upon contact with the ground. This is the case, for example, when the load wheel raises the load arm.

[0010] Preferably, the first and second curved sections are connected to each other by a transition section whose shape is adapted to the contact element. The transition section can be arranged between the first and second curved sections so that the first and second curved sections are at the correct distance from each other. The distance is sufficiently large that the contact element only ever rests against one curved section.

[0011] In a preferred embodiment, it has proven advantageous to partially incline the first curved section toward the horizontal in such a way that the load arm is raised at least approximately evenly in the area of ​​its root by the lifting device and in the area of ​​the fork tip by the load wheel lever. Particularly in a self-propelled vehicle (AGV), the horizontal alignment of the load section is important for a laser scanner scanning the surroundings. An inclination of the laser scanner when raising or lowering the load section could lead to an incorrect assessment of the surroundings and thus to error detection.

[0012] The contact element advantageously moves along the curved sections when raising and lowering the load part. The curved sections preferably determine the position of the load part in every position.

[0013] In a preferred embodiment, when the third fulcrum is lowered, the lifting device pulls on the kinematic rod, causing the load wheel to pivot completely or partially into the load arm. During this lifting of the load wheel, the kinematic rod functions as a pull rod.

[0014] When the load arm is lifted, with the load wheel swinging out of the load arm and lifting the tip of the load arm, the kinematic rod is subjected to compression.

[0015] In a preferred embodiment, the first fulcrum is moved relative to the drive part.

[0016] For the specific design of the curved track, it has proven particularly advantageous to equip the second curved section with at least two straight sections that have a different gradient or a different inclination relative to the horizontal.

[0017] A preferred embodiment of the invention is explained below with reference to the figures: Fig. 1a-c show an industrial truck with a lowered, partially and incompletely raised load section, Fig. 1D ac show a detailed view of the system on the curved track after Fig. 3 in detail, Fig. 2 shows the structure of the load wheel hub and Fig. 3 shows the example of a curved path.

[0018] Fig. Figure 1a shows an industrial truck 10, which may also be an automatically steered vehicle. The industrial truck 10 has a drive section 12 with a load section 14. The drive section 12 has a driven and steered wheel 16, which is responsible for propelling the industrial truck. The load section 14 is supported by load wheels 18, which are located at the end of the respective load arm 20 remote from the drive section 12. The load section is mounted in the drive section so that it can move essentially vertically. This can be achieved, for example, by a linear guide between the load section and the drive section.

[0019] Fig. Figure 1b shows how the load arms are raised. For this purpose, the load part 14 is raised relative to the drive part 12. The lifting movement is transmitted via a kinematic rod 22 to a load wheel lever 24, which pivots out from the load arm 20 and thus supports the load arm 20 in the raised position. To understand the movement, it is important to realize that the drive part 12 does not change its position. The load part 14 is raised relative to the drive part 12 via a lifting device, for example a hydraulic cylinder. This movement takes place in the area of ​​the load arm root, while in the area of ​​the load arm tip, the load wheel lever is pivoted to raise it. Even from this basic kinematic consideration—on the one hand, a linear lifting movement and on the other, a pivoting movement—it is clear that these two movements must be coordinated with one another.If the load arm tip lifts faster than the load wheel root, the vehicle tilts backwards and vice versa.

[0020] Fig. 1c shows the fully raised position of the load arms 20, with the load wheel lever 24 almost vertical. Fig. 1c also shows how a bell crank 26 has changed its position in a curved path 28. Compared to the Fig. 1a clearly shows that a first fulcrum 30 has changed its position relative to the drive part 12. Here, the first fulcrum moves toward the load arm.

[0021] Fig. 2 shows a schematic view of the load stroke with a kinematic rod 22, a deflection lever 26 of a curved track 30 and a load wheel lever 24 which has a load wheel 18 at its free end.

[0022] The kinematic rod 22 is a substantially straight rod having a connecting section 32 to the bell crank 26 at its end facing the load part. The connecting section 32 consists of two parallel holding sections 34 with a through-bore 36. The holding sections form a fork-like receptacle for the bell crank 26. The bell crank 26 is received between the holding sections 34, and the through-bore 36 serves to pivotally attach the kinematic rod to the bell crank 26. The opposite end of the kinematic rod 22 has a through-bore 38 extending transversely to the longitudinal direction of the rod, with which a pivotable connection to the load wheel lever 24 can be established.

[0023] The load wheel lever 24 is pivotally connected at one end via two protruding fastening sections 40, 42 to the through-bore 38 of the kinematic rod 22. The opposite end of the load wheel lever 24 has two fork-shaped, protruding fastening sections 44, 46, each with a through-bore 48, via which the load wheel 18 is mounted. The illustrated embodiment shows a load wheel 18; tandem rollers or twin rollers for the load wheel are also common. The load wheel lever 24 has a pivot point 50, with which it is pivotally mounted in the load arm. By a pulling movement, the load arm lever is raised until it reaches the Fig. 2, almost horizontal position. By applying a pressure, the load wheel lever 24 pivots its pivot point 50 and straightens up to support the raised load part.

[0024] The Fig. The deflection lever 26 shown in Figure 2 is formed in one piece. The deflection lever 26 has a slightly curved contour, with the fulcrums 52 and 54 located at the free ends of the curved contour, while the second fulcrum for connection to the kinematic rod 22 is located between the first and third fulcrums. The third fulcrum 52 has a through-bore through which a connection is made to a lifting device, for example a lifting cylinder. The connection can be made directly between the lifting device and the deflection lever 26 or indirectly, for example by the deflection lever 26 being hinged to the load part or a load frame, which is raised or lowered by the lifting device. In the illustrated embodiment, the first fulcrum 54 has a roller 56 that runs within the curved track 28.By raising the lifting device, the kinematic rod 22 is moved via a circular movement of the bell crank around the third fulcrum 52, pivoting the load wheel lever 24 so that the load wheel lever is erected. With a fixed first pivoting fulcrum, the second fulcrum would describe a circular movement, causing the load arm to also move horizontally in the area of ​​its base. This movement is compensated for by the contact element 58, which, when the third fulcrum 52 is raised, moves along the curved path 28 from the position shown toward the load wheel.

[0025] The curved track 28 is in Fig.3 in detail. The curved path 28 has a first curved section 60 and a second curved section 62. An arcuate transition section 64 is shown between the first and the second curved section. The first curved section 60 has two linear sections 66 and 68, which have a different gradient. The first linear section 68, like the second curved section 62, is essentially horizontally oriented. The linear section 66 is inclined towards the contact surface of the vehicle. This means that when the third fulcrum 52 is raised, the load wheel 18 pivots into a position below the load arm. The first fulcrum 54 moves from the horizontal linear section 68 to the linear section 66, whereby the first fulcrum is pressed downwards against the direction of lifting.This results in the angular position of the bell crank being raised more than with the horizontal alignment of the cam track in area 68, so that the load wheel lever 24 pivots more strongly into the raised position.

[0026] The curved track area formed by sections 62 and 68 is effective when the load arms are largely lowered, and is therefore particularly effective when moving into and out of a closed pallet. Section 62 holds the deflection lever when the load wheel 18 is not in contact with the ground. Section 62 holds the deflection lever as long as it is folded away from section 68 until the load wheel touches the ground again or hangs vertically. 10 industrial trucks 12 Drive part 14 Load part 16 steered wheels 18 cargo bike 20 load arm 22 Kinematic rod 24 load wheel levers 26 bell crankshaft 28 curved track 30 Leverage point 32 connecting section 34 stopping sections 36 through hole 40 fastening section 42 fastening section 44 Fastening section 46 Fastening section 48 through hole 50 articulation point 52 Leverage point 54 leverage points 56 roll 58 Contact element 60 first curve section 62 second curve section 64 Transition section 66 first linear section 68 second linear section QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] EP 3 718 854 B1

[0002] EP 1 690 823 A2

[0003]

Claims

[1] Industrial truck (10) with a drive and a load part (12, 14), which has a load wheel lift, which has a deflection lever (26) for each load arm (20), a kinematic rod (22), a load wheel lever (24) with at least one load wheel (18), wherein the deflection lever (26) is designed as a three-point lever, of which a first fulcrum (54) is mounted on the drive part, a second fulcrum is connected to the kinematic rod and a third fulcrum (52) cooperates with a lifting device, characterized by that the first fulcrum (54) has a contact element (58) which is movably mounted along a curved path (60, 62, 64). [2] Industrial truck according to claim 1, characterized by that the contact element (58) is designed as a sliding element or a roller element. [3] Industrial truck according to claim 1 or 2, characterized bythat the curved path has a second curved section (62) against which the contact element (58) rests when the load wheel folds in without contact with the ground. [4] Industrial truck according to one of claims 1 to 3, characterized by that the curved path has a first curved section (60) against which the contact element rests when the load wheel lifts the load part via the deflection lever. [5] Industrial truck according to one of claims 1 to 4, characterized by that the first and second curve sections (60, 62) are connected to one another via a transition section (64) whose shape is adapted to the contact element. [6] Industrial truck according to one of claims 1 to 5, characterized by that the first curve section (60) is inclined relative to a horizontal. [7] Industrial truck according to claim 6, characterized bythat the first curve section (60) is inclined relative to the horizontal in such a way that the load arm is raised at least approximately uniformly in the region of its root by the lifting device and in the region of its tip by the load wheel lever (24). [8] Industrial truck according to one of claims 1 to 7, characterized by that when raising and lowering the load part, the contact element (58) moves along the curve sections. [9] Industrial truck according to one of claims 1 to 8, characterized by that when the third lever point is lowered with the lifting device, the bell crank is pulled so that the load wheel is pivoted into the load arm. [10] Industrial truck according to claim 9, characterized by that the first fulcrum moves relative to the load part. [11] Industrial truck according to one of claims 1 to 10, characterized bythat the curved path has a first curved section which has at least two different gradients along its course. [12] Industrial truck according to claim 11, characterized by that the first curve section has at least two straight sections with different gradients.

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