INDUSTRIAL TRUCK COMPRISING A DEVICE FOR REDUCING VIBRATIONS

Abstract

The invention relates to an industrial truck comprising a mast (8), a load-carrying apparatus (36), which can be moved upwards and downwards thereon and which has at least one load-receiving means for receiving a load that is to be transported, and a support structure (24) connecting the load-receiving means to the mast (8), the load receiving means having a load-carrying arrangement (41) connected to the support structure (24), and a device for reducing vibrations, characterised in that the device for reducing vibrations has at least one load support (50), which covers the load-carrying arrangement (41) at the top at least in regions, on which support a load received by the load-carrying apparatus (36) can be supported and which support is provided so as to be movable to a limited extent on the load-carrying arrangement (41) such that it can perform vibration-reducing movements relative to the load-carrying arrangement (41).

Claims

1. An industrial truck comprising: a mast; a load-carrying apparatus capable of being moved upwards and downwards thereon and which has at least one load-receiving means for receiving a load that is to be transported and a support structure connecting the load-receiving means to the mast, the load-receiving means having a load-carrying arrangement connected to the support structure; and a device for reducing vibrations, wherein the device for reducing vibrations has at least one load support, which covers the load-carrying arrangement at the top at least in regions, wherein a load received by the load-carrying apparatus can be supported on the at least one load support, wherein the at least one load support is provided so as to be movable to a limited extent on the load-carrying arrangement such that the at least one load support can perform vibration-reducing movements relative to the load-carrying arrangement.

2. The industrial truck according to claim 1, wherein the load-carrying arrangement comprises at least one load-carrying arm on which the load support is retained in order to perform vibration-reducing movements relative to said load-carrying arm.

3. The industrial truck according to claim 2, wherein the load-carrying arrangement comprises a load-carrying fork having a pair of load-carrying arms, wherein each of the load-carrying arms carries a portion of the load support assigned to said load-carrying arm, the portions of the load support being guided on load-carrying arms so as to be moveable to a limited extent in the longitudinal direction of said arms such that the portions of the load support can perform vibration-reducing movements in the longitudinal direction of the load-carrying arms.

4. The industrial truck according to claim 3, wherein the upper surface and the two lateral sides adjacent thereto of each of the load-carrying arms are covered on the outside by a portion of the load support that is assigned in each case.

5. The industrial truck according to claim 3 4, wherein the portions of the load support are supported on rollers which are rotatably mounted on the load-carrying arms such that the portions of the load support can perform vibration-reducing movements relative to the load-carrying arms when the rollers rotate.

6. The industrial truck according to claim 1, wherein the load support is coupled to the load-carrying arrangement by a passive damping system or an active damping system, which influences the movement of the load support relative to the load-carrying arrangement.

7. The industrial truck according to claim 6, wherein the damping system comprises a friction-damping arrangement.

8. The industrial truck according to claim 7, wherein the friction-damping arrangement comprises at least one hydraulic friction-damping cylinder or pneumatic friction-damping cylinder.

9. The industrial truck according to claim 6, wherein the damping system comprises a spring arrangement.

10. The industrial truck according to claim 6, wherein the damping system comprises at least one active component, the active component being at least one controllable hydraulic cylinder, at least one controllable pneumatic cylinder, or at least one controllable electric motor, the active component of the damping system acting between the load-carrying arrangement and the load support in order to apply pressure to the load support in a vibration-reducing manner.

11. The industrial truck according to claim 1, wherein the industrial truck is designed as a sideloader, which has a load-carrying fork having load-carrying arms as the load-carrying arrangement, which arms are positioned or can be oriented transversely to the straightforward direction of travel of the industrial truck, the load support being capable of performing vibration-reducing movements along the load-carrying arms and therefore transversely to the straightforward direction of travel of the industrial truck.

12. The industrial truck according to claim 1, wherein the device for reducing vibrations can be selectively activatable and deactivatable.

13. The industrial truck according to claim 12, wherein the device for reducing vibrations can be automatically activatable and deactivatable depending on one or more of the particular operating state of the industrial truck or the industrial truck being stopped in certain surroundings.

14. The industrial truck according to claim 11, wherein the device for reducing vibrations is controllable depending on one or more of the orientation of the load-carrying arms, the lifted vertical position of the load-carrying arms or the industrial truck being stopped in certain surroundings.

Description

[0036] Embodiments of the invention are described below with reference to the figures.

[0037] FIG. 1 is a side view of an embodiment of an industrial truck according to the invention, which is designed as a tri-lateral high-bay stacker.

[0038] FIG. 2a is a perspective view of a tri-lateral high-bay stacker according to the invention which is very similar to the tri-lateral high-bay stacker from FIG. 1.

[0039] FIG. 2b is an enlarged view of a region marked B in FIG. 2a, a load support portion being shown with some of it removed in order to make rollers visible.

[0040] FIG. 3a is a sectional side view with the sectional plane indicated at A-A in FIG. 3b of a load-carrying arm having a load-support portion resting thereon.

[0041] FIG. 3b is a section through the arrangement from FIG. 3a with the sectional plane indicated at B-B in FIG. 3a.

[0042] FIG. 3c shows the arrangement from FIG. 3b, namely a pair of load-carrying arms with load-support portions resting thereon which engage under a pallet.

[0043] FIG. 4a and FIG. 4b are side views of a load-carrying arm with fork uprights and a load support portion resting on the load-carrying arm and with components of a vibration-damping system which are arranged laterally on the fork uprights, the load-support portion being shown in a zero position in FIG. 4a and in a deflected position in FIG. 4b.

[0044] FIG. 1 is a side view of an embodiment of an industrial truck according to the invention, in particular a high-bay stacker which is designed as a tri-lateral stacker.

[0045] The industrial truck comprises a chassis 6 supported via wheels 2 on the ground 4 and a mast 8 vertically fastened to the chassis 6. The mast 8 is constructed of multiple parts so as to be telescopically extendable, as can be seen from FIG. 1 by the extended position indicated by dashed lines. At the furthest extendable telescopic stage 10 of the mast 8, a cab 12 is attached such that it can move vertically by means of a cab support 24 in the form of a support structure. The cab 12 is constructed as a lifting driver's cabin, which has a frame comprising a cabin floor, back wall, side walls and driver overheard guard 22. In the front of the cab 12, a lateral push frame guide 26 is fixed to the cab support 24 and in this example, is formed from two fixed vertical columns 28, which have guide profiles 30 on their ends and retaining rails 32, for the lateral push frame 34, which can move longitudinally in said guide profiles.

[0046] The lateral push frame guide 26 allows for a laterally horizontal movement of the lateral push frame 34 in a plane transverse to the straightforward direction of travel G of the industrial truck (over-push function). This is a specific option of the industrial truck shown in FIG. 1. The lateral push frame 34 can be fixed directly to the support structure 24 in the case of models not having an over-push function (in particular at the front of the cab support).

[0047] A load-carrying apparatus 36, which is known per se, is arranged on the lateral push frame 34 so as to be laterally movable, transversely to the straightforward direction of travel G of the industrial truck. It comprises a pivoting pusher 38 that is movable on the lateral push frame 34, having an additional mast 40 arranged on the front thereof, on which platform a load-carrying fork 42 having a fork support arrangement is vertically movable as a load-carrying arrangement. The additional mast 40 can be pivoted together with the load-carrying fork 42 about the vertical axis 44 between the position shown in FIG. 1, in which the load-carrying fork 42 and its load-carrying arms 43 are oriented laterally (transverse orientation to the left in relation to the straightforward direction of travel G), and a position in which they are oriented in an opposite lateral position (transverse orientation to the right) of the load-carrying arms 43.

[0048] The special feature of the industrial truck according to the invention is a device for reducing vibrations which is designed to reduce vibrations with deflection components in the longitudinal direction of the load-carrying fork arms 43. For this purpose, in the embodiment shown, a load support 50 is provided in two portions 50a and 50b, which load support is movable to a limited extent relative to the load-carrying arrangement 41 and the associated fork arms 43. The load support 50 forms an interface capable of vibration-reducing movements in the longitudinal direction of the load-carrying fork arms 43 between the load-carrying fork 42 and a load received thereon (not shown). Each of the load-carrying fork arms 43 is assigned a particular portion 50a and 50b of the load support. Each portion 50a and 50b of the load support is a sleeve element resting on the load-carrying fork arm 43 assigned thereto and guided thereon for limited movement in the longitudinal direction thereof, which element covers the outside of the load-carrying fork arm 43 at least on its upper surface 52 and on the lateral sides 54 adjacent thereto.

[0049] The industrial truck shown in perspective in FIG. 2a is likewise a tri-lateral stacker having a device for reducing vibrations, which only marginally differs from the industrial truck shown in FIG. 1 for the purposes of explaining the invention. The statements made in relation to the industrial truck in FIG. 1 also apply in the same way to the industrial truck in FIG. 2. Features in FIG. 2a, which correspond objectively or functionally to features in FIG. 1, are correspondingly marked with the same reference numerals as the relevant features in FIG. 1.

[0050] In FIG. 2a and in particular in FIG. 2b, which is an enlargement of the detail indicated at B in FIG. 2a, some details of the device for reducing vibrations can be seen better. In the case of the industrial truck according to FIG. 2a, the device for reducing vibrations also has the same kind of sleeve elements 50a, 50b as portions of the load support 50, which each cover the outside of a fork arm 43 on the upper surface 52 and on the lateral sides 54. The portions 50a, 50b of the load support 50 do not have to be closed on the underneath. In this respect, a wrap-around underneath, which prevents the particular portion 50a, 50b from slipping off the load-carrying arm 43 assigned to it, suffices (c.f. also FIG. 3a-3c in this respect).

[0051] On both lateral sides 54, each load-carrying arm 43 has a set of rollers 56, which are fastened to the particular load-carrying arm 43 so as to be rotatable about horizontal axes of rotation 58 that extend in parallel with one another and support the relevant portion 50a or 50b on its surface 53 facing the upper side 52 of the load-carrying arm 43 such that the portions 50a, 50b of the load support 50 can perform vibration-reducing movements relative to the load-carrying arms 43, 43 while the rollers 56 are rotating. In FIG. 2a and FIG. 2b, one of the load-supporting portions 50a is shown with part of it broken away in order to make the rollers 56 visible.

[0052] The principle of supporting the portions 50a, 50b on the fork arms 43 on rollers can also be seen in the sectional views in FIG. 3a-3c. The uppermost positions of the rollers 56 are slightly higher than the upper surface 52 of the fork arms such that the surface 53 of the portions 50a, 50b is preferably exclusively supported on the rollers. The side walls 60 on the lateral sides of the portions 50a, 50b wrap around the end faces of the rollers 56 that point outwards to the sides, wrap-around portions 62 protruding from the lower ends of the side walls 60 that are on the lateral sides, which portions wrap around the rollers 56 underneath, leaving a small gap such that the portions 50a, 50b of the load support 50 on each of the load-carrying arms 43 are protected from rising up and are movably guided in the longitudinal direction of the load-carrying arms 43.

[0053] The portions 50a, 50b are coupled to the load-carrying arrangement 41 by a damping system 64 which influences the movement of the load support 50 relative to the load-carrying arrangement 41 (load-carrying fork 42). For each portion 50a, 50b of the load support 50, the damping system 64 comprises one hydraulic damping cylinder (optionally also an actuator cylinder) 70 and one helical spring 72 each, which are arranged substantially in parallel with one another in the embodiment according to FIGS. 2a-2b and 3a-3c and each connect a vertical portion 66 (upright) of a relevant load-carrying arm 43 to a rear stop plate 68 of an assigned portion 50a or 50b. According to one variant of the device for reducing vibrations, the damping cylinder 70 and the spring 72 form a passive damping system. The spring 72 is designed such that it attempts to force the relevant portion 50a or 50b of the load support 50 in each case towards a target rest position should the portion 50a or 50b have deflected out of said target rest position in each case during its vibration compensation movements. The damping cylinder 70 is designed such that it exerts a braking effect on the vibration movements of the portion 50a or 50b of the load support 50 connected thereto in order to convert kinetic energy into another form of energy, in particular heat, such that vibration damping of vibrations of the industrial truck, in particular of the mast 8, takes place with vibrating components in the longitudinal direction of the load-carrying arms 43. In a sideloader, if the load-carrying arms 43 are in a transverse position, transverse vibrations are therefore reduced.

[0054] FIGS. 4a and 4b are side views of a variant of a damping system 64x comprising a cylinder 70x and a pair of springs 72x on a load-carrying arm having an assigned portion 50a of the load support, and specifically in a target rest position of the portion 50a (FIG. 4a) and in a deflected position of the portion 50a (FIG. 4b). The portion 50a extends by means of a cantilever 73 as far as into the region of the vertical portion or upright 66 of the load-carrying arm and is connected there in an articulated manner to a lever arm 75 of a two-armed lever 76, which is mounted on the upright 66 so as to be rotatable about a horizontal axis. The second arm 78 of the lever 76 acts on the pair of springs 72x, which apply pressure to the lever 76 and therefore to the portion 50a of the load support towards a central target rest position. For this purpose, the second arm 78 of the lever 76 is connected to the pair of springs at the junction 80 of the pair of springs. Furthermore, the second arm 78 of the lever 76 is connected at the junction 80 to the piston rod end 82 of the hydraulic damping cylinder 70x, which is laterally hinged to the load-carrying arm upright 66 at the other end. Instead of the damping cylinder 70x, or in addition thereto, a separate friction-damping arrangement comprising a pair of friction elements consisting, for example, of a friction lug or friction rail and a friction bracket, could be provided, which can have friction linings and, for example, can have a frictional effect between the lever 76 and the load-carrying arm upright 66.

[0055] One variant of the device for reducing vibrations according to FIGS. 4a and 4b could be that the hydraulic cylinder 70x is operable as an actuator in each case, which can actively move the portion 50a of the load support relative to the load-carrying arm and, for example, reinstate the target rest position (zero position) should the pair of springs 72x not be capable of doing so alone. The target rest position (zero position) of the portion 50a can be monitored by means of sensors (not shown), which are connected to a control device which in turn serves to control the actuator. The maximum permissible relative movement between the portion 50a of the load support and the load-carrying arm 43 can also be detected and monitored by means of sensors (not shown) and limited by stop means.

[0056] It should be pointed out that according to variants of the embodiments shown, the rigidity of the spring arrangements 72 and 72x and/or the frictional effect of the friction-damping arrangement and brake effect of the damping cylinder 70 and 70x can be controllable depending on certain operating parameters or operating conditions of the industrial truck in order to modulate the vibration-damping effect as required.

[0057] While the industrial truck is travelling in a narrow aisle of a high-bay warehouse, the device for reducing vibrations would, for example, be activated, the friction-damping arrangement providing a frictional effect adapted to the current situation. If, when travelling over uneven ground, a transverse acceleration occurs at the mast 8 and at the cab support 24 and therefore at the load-carrying arms, which are oriented transversely to the straightforward direction of travel G, the transverse acceleration is transferred to the load support and any load that might be supported thereon by means of the friction-damping arrangement and the spring arrangement 72x. If the inertial force of the “decoupled or soft-coupled” masses exceeds the value of the adjusted frictional force and the spring force acting in parallel, a relative movement occurs between the load support and the load-carrying arms. This relative movement backwards and forwards relative to the target rest position reduces the overall vibration amplitude and kinetic energy is converted primarily into heat in the friction damping arrangement.

[0058] It should be pointed out that according to a variant of the device for reducing vibrations having at least one active component, the cylinder 70x shown in FIG. 4a and FIG. 4b constitutes such an active component as an actively controlled and dynamically effective actuator in order to apply pressure to the load support 50 in a manner that reduces vibrations.

[0059] The cylinder 70 in FIGS. 3a-3c could also be an active actuator cylinder in a corresponding embodiment.

[0060] A control device is provided in such an active system in order to control the active components. Furthermore, sensors can be provided which detect the vibration amplitudes of the mast or components arranged thereon in a height-adjustable manner, the control device being capable of processing data from said sensors in order to control the active components in the sense of optimised vibration reduction. In this sense, sensors can also be provided which detect the relative movement of the load support relative to the load-carrying arrangement.

[0061] Even though a man-up industrial truck comprising a vertically movable cab has been described as the embodiment of the invention, the invention is not intended to be limited thereto. It is just as applicable to so-called man-down industrial trucks having a fixed cab near the ground or “driverless” industrial trucks, for example automatic bay operating equipment.