DE60007767T2 - Device in a hydraulic lifting device - Google Patents

Abstract

The invention relates to a hydraulic lifting apparatus (1) having a lifting arrangement (3, 12), which is vertically adjustable and which is arranged to be turnable about an axis (A). A first hydraulic actuator (16) is arranged to raise and lower the lifting arrangement (3, 12) and a second hydraulic actuator (30, 32) is arranged to turn the lifting arrangement (3, 12) about said axis (A), and both actuators are connected to a common hydraulic pressure source (46, 47). Furthermore, a change-over means (54) is arranged to connect one of said first actuator (16) and said second actuator (30, 32) to said hydraulic pressure source (46, 47). According to one embodiment of the invention, the second actuator is composed of two opposed hydraulic cylinders (30, 32) which have at least one common point of engagement (P1).

Description

The The present invention relates to a hydraulic lifting device according to the preamble of Claim 1.

A such lifting device is known from GB 615 265 A.

technical background

hydraulic Lifting devices, e.g. Forklift trucks are usually vertical adjustable fork on which is arranged under a pallet and then raised by means of hydraulic actuation. In some make is it desirable that Fork in particular about its longitudinal axis to be able to pivot i.e. from the operator to the right or left. This has already been achieved, for example, by the construction method "ERGO 800HT" of the applicant, in which a worm screw is used to rotate the fork about an axis.

One Disadvantage of this construction is that for the rotational movement a separate Power supply must be provided, and that the operator different actuating means must press, depending on whether the fork is raised or lowered or pivoted shall be. Furthermore, the known construction has a relatively complicated Structure as well as several movable, mechanical components, which wear out and require maintenance.

moreover For example, the swivel angle is relative to prior art designs limited, usually less than 20 °.

Finally exists Another problem is that the pivoting structures according to the state The technique is often bulky and not as compact as it often he wishes is.

This leads to the result that forklift truck with swiveling fork is not in huge Quantities are sold.

Summary the invention

One The aim of the invention is an improved, hydraulic To propose lifting device, which in a simple structure allows pivoting of the lifting means.

One Another object of the invention is to provide a compact device to propose for pivoting the lifting device.

These Goals are in a lifting device of the type mentioned achieved, which is characterized by a second, hydraulic actuator, which connected to the hydraulic pressure source and turning the lifting arrangement is formed about the axis, and by a switching means, which is arranged such that it is the first actuator or the second actuator connects to the hydrau lic pressure source. The term "actuator" basically includes all Types of actuators, although one type of double acting Actuator usually for the practical application will be suitable. With "double acting actuator" is an actuator addressed, both to practice and to hold across from a force is formed in both directions of rotation.

There same source of energy for both used the vertical movement as well as for the pivoting movement will, lets the actuating means designed so that its handling by the operator easier becomes. The operator only has to change the switching means to the correct one Position and then operate the hydraulic pressure source.

One hydraulic actuator can be used to pivot the lifting arrangement in a relatively large angular range be formed, the hydraulic at the same time less movable Requires components, as is the case with mechanical swiveling devices according to the state the technique is the case.

The Lifting arrangement preferably comprises a holding element, which means of the first actuator along a vertical portion of the frame is displaceable, and a lifting structure, which on the holding element arranged and rotatably mounted on the axis of rotation, wherein the second actuator a first connection point with the holding element and a second connection point with the lift structure.

Of the Connection point of the actuator with the holding element is preferably closer to the axis of rotation arranged as its connection points with the lifting structure, which leads to a compact construction.

The mentioned above, usually desired double action is appropriate by ensures two single-acting cylinder, which arranged such are that they act in opposite directions. consequently is every cylinder for exercising one Force in one direction of rotation and to hold against one Power in the opposite direction capable. In this way Overall, a double-acting actuator is formed, as above is addressed.

The Cylinders preferably have at least one common connection point on, causing for the practice is given a simpler and cheaper construction.

According to one embodiment The cylinders each have a connection point with the lifting structure and a common connection point arranged therebetween with the holding element. The term "in between" does not necessarily mean that the common connection point on a line between the other connection points is arranged, but the three connection points can be very probably the cornerstones of an imaginary Forming triangle. In such a configuration results in a particularly compact construction. The compactness results the fact that the double-acting actuator, which consists of the formed two single-acting cylinders, three connection points having a force between on the one hand the two outer connection points and on the other hand, the middle connection point is effected.

Of the Connection point with the holding element is preferably closer to the Rotary axis arranged as each connection point with the lifting structure, wherein a particularly preferred embodiment provides that the connection point with the retaining element within an imaginary Triangle is arranged, which of the connection points with the Lifting structure and the rotation axis is formed. Because of stability the axis of rotation is appropriate relatively high arranged on the lifting structure and thus forms an upper corner of the triangle. Furthermore, the connection point with the holding element be arranged on a vertical line through the axis of rotation.

According to one embodiment is provided that between each cylinder and the pressure source a pressure controllable check valve is arranged, which to guarantee a flow is formed only by one of the cylinders when the pressure at the second cylinder exceeds a predetermined limit. this leads to to the above mentioned Double effect.

Of the Pressure in the hydraulic pressure source can be achieved by means of a lever, e.g. by means of the handle of the lifting device, manually controllable be. In this case, the operator himself carries out the lifting or pivoting work over the Lever, the advantages of the invention are obvious. There is a big one Advantage in that independent from the to be executed Operation only one type of pumping movement can be performed got to. The only necessary setting is switching the switching element before the pumping movement.

Short description the drawings

below the present invention is explained in more detail with reference to the accompanying drawings, in which for the purpose of illustration a preferred embodiment the invention is reproduced. Showing:

1 an exploded view of a stacker according to the invention and

2 a schematic diagram of a valve means according to 1 ,

description a preferred embodiment

The lifting device shown in the accompanying drawings is of a stacker 1 formed, which is a frame 2 and a horizontal lifting structure in the form of a lifting fork 3 having. The frame 2 includes a horizontal section 4 , which by means of a suitable component 5 is in contact with the ground, and a vertical section 6 extending from the horizontal section 4 extends upwards. The lifting fork 3 is arranged substantially horizontally and along the vertical section 6 of the frame 2 between a lowered position, in which the fork 3 on a level with the vertical section of the frame 2 located, and a raised position displaceable, in which the fork 3 at a level with the upper end of the vertical portion of the frame 2 located.

In the embodiment shown, the horizontal section comprises 4 of the frame 2 two carriers 7 , each at its front end 7a from a wheel 8th are supported. The back ends of the straps 7 open into a crossbeam 9 which in turn is from two other wheels 8th is supported. Two more carriers 10 extend from the cross member 9 vertically upwards and form together with two transverse support elements 11 the vertical section 6 of the frame 2 , All carriers 7 . 9 . 10 and the support elements 11 are suitably rigidly connected to each other, wherein they may preferably be welded together.

A holding element in the form of a carriage 12 is between the vertical straps 10 arranged in known manner so that it is along the carrier 10 is displaceable up and down. Usually a chain 13 or a similar power transmission element between the carriage 12 and the frame 2 provided, the chain 13 via a pulley 14 is guided, which at one end of the piston 15 a hydraulic cylinder 16 is arranged. In the embodiment shown, the carriage 12 an end wall 17 and two side walls 18 on, with the side walls 18 on the inside 10a the carrier 10 are arranged and the end wall 17 between the carriers 10 extends.

A pivot 20 on which the lifting fork 3 pivotally mounted, protrudes from the end wall 17 of the sled 12 horizontally in front. In the illustrated embodiment, the lifting fork 3 two elongated arms 21 on, which with a breast member arranged therebetween 22 are rigidly connected. The breast member 22 is with an opening 23 equipped, in which the pivot pin 20 is insertable to the end wall 17 and consequently the entire lifting fork 3 to wear. This is the lifting fork 3 about the axis A of the pivot 20 rotatable. The opening 23 is appropriate above the attachment points of the arms 21 with the breast member 22 arranged.

The breast member 22 is preferably of two parallel plates 27a . 27b and a cylinder 28 formed, which is between the plates 27a . 27b extends. The opening 23 extends at least through the closest to the carriage 12 arranged plate 27a so that the pivot pin 20 in the cylinder 28 insertable and, for example by means of a sliding bearing (not shown) can be fastened.

A second, hydraulic actuator 30 . 32 is between the lifting fork 3 and the sled 12 arranged to the position of the lifting fork 3 concerning the sled 12 to change. In the illustrated preferred embodiment of the invention, the breast member is 22 the lifting fork 3 , expediently only the closest to the carriage 12 arranged plate 27a , with another opening 31 fitted. This opening 31 is arcuate and below the first opening 23 arranged. Furthermore, a pin extends 33 , which at the end wall 17 of the sled 12 is rigidly fixed, through the opening 31 , A hydraulic cylinder 30 has a first connection point P1 with the carriage 12 and a second connection point P2 with the lift structure 3 on. Here is the piston 36 of the cylinder 30 eg rotatable on the pin 33 fixed, which in this case forms the point P1, while its other end 30a at a point P2, which is preferably close to the outer side of the breast member 22 and preferably near the attachment point of one of the arms 21 of the thoracic limb 22 is arranged rotatably on the chest member 22 is attached. Another hydraulic cylinder 32 is in a similar way between the pin 33 and a third connection point P3 is arranged. Of course, one or both cylinders 30 . 32 be arranged vice versa, in which case the piston 36 . 38 on the breast member 22 is fixed.

The three hydraulic cylinders 16 . 30 . 32 are over lines 41 . 42 . 43 with a valve means 40 connected, which in turn via lines 44 . 45 with a hydraulic pressure source in the form of a pressure change agent 46 and a fluid container 47 are connected. Between the valve means 40 and the fluid container 47 is a check valve 48 arranged.

The valve means 40 connects the cylinders 16 . 30 . 32 selectively with the pressure change agent 46 and in the embodiment according to FIG 2 a three-way valve 50 , such as a gate valve, as well as two pressure-controllable check valves 51 . 52 , such as pilot operated pressure relief valves, on which crosswise with pressure lines 51a . 52a are connected. The valve 51 is designed such that there is a flow in the direction of the cylinder 30 while preventing current in the opposite direction. Meanwhile, the pressure acts on the valve 52 over the line 52a on the valve 51 where the valve 51 opens when a predetermined, adjustable pressure on the valve 52 has been achieved to also get a stream from the cylinder 30 to enable. The valve 52 works in the reverse way.

In a first position, the first cylinder 16 with the pressure change agent 46 connected so that the pressure in the cylinder 16 by means of the pressure change agent 46 is controllable. A pressure increase causes the removal of the piston 15 out of the cylinder 16 so the sled 12 and consequently the lifting fork 3 along the vertical section 6 of the frame 2 is moved upward while a pressure drop due to the weight of the lifting fork 3 the insertion of the piston 15 in the cylinder 16 causes.

In a second position is the cylinder 30 over the valve 51 with the pressure change agent 46 connected. Will the pressure in the cylinder 30 by means of the pressure change agent 46 increases, so does the piston 36 of the cylinder 30 against the pin 33 and against the piston 38 of the second cylinder 32 pressed. Reaches the pressure on the valve 51 which is the valve 52 over the line 51a influenced, a sufficiently large value, so opens the valve 52 , leading to an expansion of the first cylinder 30 , to a contraction of the second cylinder 32 and to a displacement of the pin 33 leading in a lateral direction, so that the lifting fork 3 is pivoted. The pin 33 then moves in the arcuate opening 31 , which also limits the pivoting movement to a predetermined maximum angle.

In a third position are the two cylinders 30 . 32 the lifting fork 3 connected in reverse, so that an increase in pressure to pivot the lifting fork 3 leads in the opposite direction.

Further, a control means 54 with the valve means 40 connected, allowing the operator to control the valve means 40 between his three positions is able.

According to one embodiment, the system is manually operable, wherein the pressure change means 46 in this case - as it is known from the prior art - has a lever which the handle 56 the forklift forms, with the handle 56 is designed to increase the pressure in the fluid system by means of pumping movements. The handle 56 is also with a means, such as a directional control valve 58 equipped to reduce the pressure in the fluid system.

In the embodiment shown, the control means 54 expedient an operating lever 55 on. The lever 55 has three positions corresponding to the three positions of the valve means 40 where the handle 56 or the directional control valve 58 in all positions can be used in different ways to the pressure in each operating cylinder 16 . 30 . 32 to change. Is the control means located 54 in the first position, so can the lifting fork 3 consequently by a pumping movement of the handle 56 lift and by pressing the directional control valve 58 the handle 56 lowering, as is known in the art. Is the control means located 54 in the second position, a pressure-increasing pumping movement in the manner described above causes a pivoting of the lifting fork 3 in one direction. Is the control means located 54 in the third position, pivoting in the opposite direction is possible. In the second and third positions is the directional control valve 58 disabled and has no function in this case.

Alternatively, the pressurization may be by means of an electrical, preferably battery powered device (not shown) as is known in the art. In an electrically powered system, the control means 54 be even simpler designed. For example, a set of four button knobs may be provided on a forklift. Each knob represents one direction (up, down, right pivot, left), and when you press a button, the valve means 40 first transferred to its appropriate position and then the pressure is changed. For example, pressing the "up" button causes the valve means 40 takes its first position and then the pressure in the cylinder 16 is increased.

In the illustrated embodiment, the forklift is with two cylinders 30 . 32 equipped to the forklift 3 but it is of course also possible that this function will be fulfilled in a corresponding manner only by means of a double-acting cylinder, although in this case the desired compactness can not be achieved in the same manner as described above. Moreover, the actuators need not necessarily be formed by hydraulic cylinders or be hydraulic at all. The principle according to the invention is correspondingly applicable to a pneumatic system.

The Lifting device according to the invention can Of course also be rigidly attached and, for example, a workstation form, which can be raised and lowered as well as pivoted is.

Claims (7)

Hydraulic lifting device comprising: - a device; - a frame ( 2 ); A holding element ( 12 ), which along a vertical section ( 6 ) of the frame ( 2 ) by means of a first, with a hydraulic pressure source ( 46 . 47 ) connectable actuator ( 16 ) is displaceable; - a lifting structure ( 3 ), which on the holding element ( 12 ) and by means of a second, with the hydraulic pressure source ( 46 . 47 ) connectable, hydraulic actuator is rotatable about an axis of rotation (A), and - a switching means ( 54 ) which is arranged such that it is the first actuator ( 16 ) or the second actuator with the hydraulic pressure source ( 46 . 47 ), characterized in that: - the second actuator comprises two oppositely disposed hydraulic cylinders ( 30 . 32 ) having; - where the cylinders ( 30 . 32 ) each have a connection point (P2, P3) with the lifting structure ( 3 ) and in each case one connection point (P1) with the retaining element ( 12 ) exhibit; - wherein the connection points (P1) with the holding element ( 12 ) are arranged within an imaginary triangle, which of the connection points (P2, P3) with the lifting structure ( 3 ) and the rotation axis (A) is formed. Hydraulic lifting device according to claim 1, wherein the connecting point (P1) with the retaining element ( 12 ) is arranged closer to the axis of rotation (A) than the connecting points (P2, P3) with the lifting structure. Hydraulic lifting device according to claim 1 or 2, wherein the cylinders ( 30 . 32 ) a common connection point (P1) with the holding element ( 12 ) exhibit. Hydraulic lifting device according to one of the preceding claims, wherein the connection point (P1) with the retaining element ( 12 ) is arranged on a vertical line through the rotation axis (A). Hydraulic lifting device according to one of the preceding claims, wherein between each cylinder ( 30 . 32 ) and the pressure source ( 46 . 47 ) a pressure controllable check valve ( 51 . 52 ) is arranged, which for ensuring a flow of only one of the cylinder ( 30 . 32 ) is formed when the pressure on the other cylinder ( 32 . 30 ) exceeds a predetermined limit. Hydraulic lifting device according to one of the preceding claims, wherein the pressure in the hydraulic pressure source ( 46 . 47 ) by means of a lever ( 56 ) is manually controllable. Hydraulic lifting device according to one of the preceding claims, wherein the pressure in the hydraulic pressure source ( 46 . 47 ) is electrically controllable.