FRAME FOR INDUSTRIAL TRUCKS

Abstract

 A frame for an industrial truck, the frame forming part of a battery compartment and comprising a back part, a front part opposed to the back part, and a side part connecting the back and the front parts on one side, thereby forming a space for the battery compartment; a bottom part in mechanical connection with any one of said front, back and side parts and comprising an area for supporting a battery and an opening extending indefinitely away from said side part; and a bar that removably confines in a closed state said opening on a side opposing said side part and being configured to transfer force between its endpoints on said bottom part.

Description

Technical Field

[0001] The present invention relates to a frame for an industrial truck. More specifically, the present invention relates to a frame of a battery driven industrial truck, such as a fork-lift truck carrying an exchangeable battery as a main power source.

Background

[0002] Industrial trucks, such as forklift trucks, are oftentimes battery powered. In some designs, the frame (or chassis) of a counterbalance forklift provides the possibility to exchange the battery from the side, by using for example a further forklift truck or a simple pallet truck. Respective frames can thus be open both laterally (to allow the battery to be removed) and in the plate below (to allow the forks of the pallet truck to enter and lift the battery) . Such open structures, despite the provision of relatively thick materials to increase its strength, has areas and points on which very high stress is concentrated. Such points or areas can be suitably reinforced with welded plates.

[0003] However, such reinforcement plates and elements may create an unbalance in height with possible disadvantages especially during assembly. To mitigate such problems, it has been proposed to weld other plates on other locations to equalize the height and facilitate handling during assembly and manufacturing. Such frames can be relatively heavy and accordingly expensive, both because of the addition of the welded plates and increased thickness of the structural plates. Disadvantages can be most pronounced at side plates whose thickness can reach, for example, 25 mm and more. In turn, such thicknesses may require dedicated cutting processes (oxy-cutting, plasma cutting), elevated processing times, associated cost, high scrap fraction, and sub-optimal cutting quality with the consequent need for careful cleaning of the contours.

[0004] There is therefore a need for an improved frame structure that does not suffer, or at least to a lesser extent, from the above-mentioned drawbacks. Especially, it is desirable to dispense with the complex, costly, and disadvantageous reinforcing measures, whilst obtaining a frame structure providing the necessary strength, rigidity and stability and providing the possibility to easily access and remove the battery.

Summary

[0005] The mentioned problems are solved by the subject-matter of the main claim. Further preferred embodiments are defined in the dependent claims. Specifically, the embodiments of the present invention may provide substantial benefits that are described in part herein.

[0006] According to an embodiment of the present invention, there is provided a frame for an industrial truck, the frame forming part of a battery compartment and comprising a back part, a front part opposed to the back part, and a side part connecting the back and the front parts on one side, thereby forming a space for the battery compartment; a bottom part in mechanical connection with any one of said front, back and side parts and comprising an area for supporting a battery and an opening extending indefinitely away from said side part; and a bar that removably confines in a closed state said opening on a side opposing said side part and being configured to transfer force between its endpoints on said bottom part.

Brief description of the drawings

[0007] Embodiments of the present invention, which are presented for better understanding the inventive concepts but which are not to be seen as limiting the invention, will now be described with reference to the figures in which:

Figures 1A and 1B

show schematic views of a frame structure according to an embodiment of the present invention;

Figures 2A to 2C

show schematic views of a lock mechanism according to an embodiment of the present invention in various views and states;

Figure 3

shows a schematic view of an embodiment in which the operation of a door mechanism and the bar remain as such independent but still may interact;

Figure 4

shows a schematic view of an embodiment in which the operation of a door mechanism interacts with the bar;

Figures 5A and 5B

show schematic views of the respective kinematics in some of the embodiments of the present invention;

Figures 6A and 6B

show schematic views of vertical locking mechanisms according to further embodiments of the present invention;
and

Figures 7A and 7B

show schematic views accompanying a calculus approach to the obtained benefits.

Detailed description

[0008] Figures 1A and 1B show schematic views of a frame structure according to an embodiment of the present invention, wherein Figure 1A shows the frame structure without a battery and Figure 1B shows the frame structure with a battery or battery case inserted. More specifically, there is shown a frame 10 for an industrial truck. The frame 10 forms at least part of a battery compartment 100 and comprises a back part 101, a front part 102 opposed to the back part 101, and a side part 103 connecting the back part 101 and the front part 102 on one side, thereby forming a space for the battery compartment 100. The frame further comprises a bottom part 104 in mechanical connection with said front, back and side parts 101, 102, 103, and comprising an area 141 for supporting a battery and an opening 142 extending indefinitely away from said side part 103. In this way, a battery can be lifted from the bottom through the opening 142 and removed from the compartment 100.

[0009] The frame further comprises a bar 110 that removably confines in a closed state said opening 142 on a side opposing said side part 103 and being configured to transfer force between its endpoints on said bottom part 104. In an open state, i.e. with bar 110 opened or removed, it is clear that whenever the frame is loaded with the weight of the battery, zones A and B may be subject to displacements and the rest of the structure may be stressed by bending and twisting moments. Embodiments of the present invention consider the removable bar 110 positioned between points A and B in order to close the structure of the frame and transfer forces between the zones A and B and accordingly making the whole structure stronger and more rigid. Optionally, the frame may comprise a hinge mechanism 131 toward a first end of the bar 110 and a lock mechanism 132 toward another end of the bar 110, which may facilitate opening and closing of the bar 110.

[0010] Preferably, the bar 110 may be manufactured from a high-strength material (e.g. S355JR, 1.0045 material). Bar 110 can thus close the frame in order to create a closed structure which is inherently more resistant to stress. The proposed solutions can make it possible to eliminate any reinforcing plates and elements, reduce the thickness of the plate material and possibly of other structural components by, for example, 5-10 mm.

[0011] As a further advantage, bar 110 once closed can also act as a stop for the battery box as can be seen from Figure 1B. There, it shown again the frame 10 with a battery or battery box 20 inserted into the battery compartment 100 and accordingly resting on at least areas of the bottom part 104. The bar 110 can preferably be positioned to fit to the lower part of the battery 20 within a given tolerance to both allow reliable exchange of the battery or batteries (with respective dimension tolerances) as well as holding securely and firmly the battery 20 during operation and movement of the industrial truck.

[0012] Figures 2A, 2B, and 2C show schematic views of a lock mechanism according to an embodiment of the present invention in various views and states. Specifically, there is shown a lock mechanism 130 that comprises a pin member for 1301 blocking a horizontal movement of the bar 110 relative to the bottom part 104. The lock mechanism 130 may further comprise a handle member 1302 actuating the member 1301 by lifting the member out of an opening in the bottom part 104. In the state shown in Figure 2B, the locking mechanism 130 is closed and the pin member 1301 engages with the bottom part 104 and consequently blocks a movement of the bar 110 relative to the bottom part 104. In the state shown in Figure 2C, the handle 1302 is lifted so as to lift accordingly the pin member 1301 which allows the bar 110 to be opened. The locking mechanism 130 may further comprise a handle rail 1303 and a spring 1304 to guide and facilitate operation and especially shown in Figures 2B and 2C.

[0013] More specifically, the locking member 1301 can be lifted manually by an operator using the handle 1302 and by releasing the member 1301 from its seat in the bottom part 104 the bar 110 can be unlocked and opened. In addition, a brick 1305 may be provided which bounds the handle and locking member to move only vertically along the handle rail 1303. The mechanism may be provided with the already mentioned spring 1304 that is adapted to return the blocking member 1301 to its initial position.

[0014] It should be clear that the so far described solutions are in principle independent from any door mechanism, being part of the frame, chassis or casing of the industrial truck. Such door mechanisms may not be essential for holding and/or securing the battery but are generally provided for safety and integrity reasons. In further embodiments of the present invention, the bar is provided with an element configured to interact with a door assembly closing said battery compartment on a side opposed to the side part. Preferably, the element may force the bar into the closed state upon closing the door.

[0015] Generally, however, the mentioned door and the bar can be moved and operated separately. For example, the operator may first open the door, bringing it to the end of its stroke, and then move the bar, which can rotate around a respective hinge. Although in such embodiments the operation of the door and the bar remain as such independent they may be still interact in some way or another. In one such embodiment the bar is provided with a locking mechanism as for example described in conjunction with above Figures 2A through 2C. At the same time, the door may provided with a further hole that may likewise engage with the locking member. The spring 1304 acts between the handle, with a handle pin 1312, and the structure welded on the bar through what may be referred to as a spring pin 1311.

[0016] As shown in Figure 3, when the door 30 is in a suitable open position the bar 110 can be fixed to the door 30 that is provided with an end-of-stroke locking plate 1310 into which the locking member can engage just like with the bottom part. Thus, by using the same opening handle and locking mechanism both the bar can be locked and secured as well as the door can be secured during exchange or maintenance operations. This may specifically inhibit the door to move until the operator has finished the battery exchange operation. Further, in this way it may not be possible to close the door 30 unless the safety lock of the handle and locking member is activated first. In summary, the door 30 can only be closed by first closing the bar 110, lifting the handle again while closing it and releasing the handle once the bar is in the correct closed position. It is to be noted that in Figure 3 there is shown the bar in both states, i.e. in a closed state 110-1 and in an open state 110-2, when the bar is fixed to the door holds the same and grants full access to the opening 142.

[0017] In further embodiments, the structural improvements obtained by the bar a described so far are combined with a kinematic mechanism that exploits the movement of the door to also move the bar. Consequently, the bar is provided with an element configured to interact with a door assembly closing said battery compartment on a side opposed to the side part, and said element generally force the bar into the closed state upon closing the door.

[0018] Figure 4 shows a schematic view of an embodiment in which the operation of a door mechanism interacts with the bar. In this embodiment an element that is configured to interact with a door assembly is interacts slidably with a rail arranged on an inner side of the door assembly. Specifically, the bar 110 is hinged to the frame (e.g. bottom part 104 thereof) by a pin 131-1 and can at least to some extent rotate around it. At the other end of the bar 110 there is a second pin 132-1, which may be integrally formed with the bar and which essentially prevents the bar from moving (as e.g. a result of deformation) in a vertical direction.

[0019] As the bar 110 rotates around hinge or pin 131-1, the seat for the second pin 132-1 in a rail along the door follows the rotation of the end of the bar itself. For the same reason, also a corresponding opening or furrow in the bottom part may not be straight but may follow an arc of the circumference around the hinge point at pin 131-1. The two pins 131-1, 132-2 may be made of a high-strength steel material with different yield strengths (higher for the pins) and may be machined accordingly. A thread can be provided into the lower parts of each pin and the pins may be fixed with e.g. self-locking nuts.

[0020] The respective kinematics are shown with greater detail in conjunction with Figures 5A and 5B. Specifically, the system as disclosed in conjunction with Figure 4 may be reduced to rods a, b, c, d as shown in Fig. 5B, corresponding to the hinge 131, the bar 110, and the door 30, and constituting in all 12 DoF (Degrees Of Freedom). In an analysis of the constraint conditions (n is the number of rods connected by the constraint under examination) it follows that at the hinge in (A) with external constraints, 2n, 2 DoF can be subtracted, at hinge (B) with external constraints, 2n), 2 DoF can be subtracted, at hinge (C) with internal constraint, 2(n-1), 2 DoF can be subtracted, at hinge (D) with internal restriction, 2(n-1), 2 DoF can be subtracted, at the sliding hinge (E) with internal restriction, 2n-3, 1 DoF can be subtracted, and at hinge (F) with external constraint, 2n, again 2 DoF can be subtracted. In all, it follows that for a total of 11 constraint conditions the degree of freedom is 12 - 11 = 1.

[0021] The bar 110 may thus also act as an end stop for the fully open door 30. On the door 30, further modifications can be made to the bar stop with the addition of a piece of elastic material (e.g. neoprene) to prevent metal-to-metal contact. Such a solution may further relieve the hinges (articulated quadrilaterals) from the end-of-travel work of the door, making the system more robust.

[0022] Optionally, the door assembly comprises a lock mechanism in turn comprising a member that slidably engages with the bar and the bottom part in a closed state. Preferably, said slidably engaging member comprises a pin arranged to engage vertically in a hole of said bar and a hole in said bottom part. Such solutions are shown for example with the safety latch and lock mechanism as follows: A further pin 133 (preferably turned and made of high strength steel) may engage with a hole made on the bar 110 and one made on the bottom part 104 of the frame. The pin 133 may ensure that the bar 110, and indeed the whole system, does not move outwards or open when the door 30 is closed. Pin 133 may be moved by a knob 135 on the outside and guided on an inner side of the door via a rail 134 and a spring, which constrains movement of the pin 133 to the vertical direction. The return spring, once the operator releases the knob 135, returns the pin 133 to its initial position, thus preventing also the operator from closing the door 30 (when open) without activating the safety latch. The door can only be closed by lifting the knob again while accompanying it in closing. However, when the door 30 is closed and couples with the underlying part of the frame through pins 132-1 and 133 a closed and boxed structure is obtained.

[0023] According to further embodiments of the present invention there is provided a vertical locking mechanism that prevents or at least inhibits the vertical degree of freedom of the bar at a distal end, assuming a rotatable hinge seat at the opposing proximal end of the bar. In one such embodiment, the vertical locking mechanism comprises a pin, bolt or screw as shown for example in Figure 6A: A pin 136 locks the bar 110 in a vertical direction to the bottom part 104 by means of respective holes and a nut 137, preferably embodied by a self-locking nut. Such a pin closed in the lower part by a nut can prevent during non-negligible deformations of the frame that the bar leaves its seat in the bottom part of the frame and thus not fulfilling the purpose of stability as described throughout the present disclosure. Such a closed pin couples the bar and the bottom part for creating an isostatic system along the z-axis (vertical).

[0024] This kind of vertical locking mechanism can be well combined with any embodiment in which the bar 110 is accessible even in a closed state through a still open door or some other opening that grants access to it also in a state in which the door 30 is closed. For example, the vertical locking mechanism as shown in Figure 6A can be well combined with the locking mechanism as disclosed in conjunction with Figures 2A through 2C, preferably at a distal position relative to the handle lock.

[0025] Figure 6B shows a schematic view of a vertical locking mechanism according to a further embodiment of the present invention, which can be in principle replace or be combined with the on described in conjunction with Figure 6A. Generally, such an embodiment considers lengthening the bar 110 along the distal end and up to the portion of the frame where it can engage with an opening thereof. In such an embodiment, the rear part 101 provides an opening 1010 suitably shaped and configured to receive the bar's end portion and constrains therefore the bar in the vertical z-direction. In this way, it is again implemented a safety lock by realizing a hyperstatic system in that direction: the back plate of the frame prevents the bar from moving along z.

[0026] As a further explanation, the following calculation can demonstrate the benefits obtained by the embodiments of the present invention, especially in view of a comparison between the strength of a closed and an open structure. These considerations may start with the assumption a circular crown-shaped section in which the ratio between thickness t and external radius Re is equal to 1/10 (Figure 7A) :

[0027] Let us denote by Ri the internal radius and by R the mean radius of the section. The area A and the circumference 1 relative to R are respectively:

[0028] Applying Bredt's formulae gives τ_zx (mean tangential stress) and θ' (specific torsion angle) respectively:



where M z is the torque and G is the tangential modulus of elasticity. Consider now the same section from which, however, an infinitesimal piece has been removed (Figure 7B). On such a section we obtain τ_(zx max) (maximum tangential tension) and θ_A^' (specific torsion angle for open structures) using the theory of the elongated rectangular cross-section:



from which follows

[0029] Considering that



one arrives at the conclusion that

[0030] That is, the open section is, with the same material and shape, extremely more deformable than the closed section and has tensions that are about 30 times greater. Consider that in closed sections the maximum tension is found in correspondence of the smallest thickness, in the case under consideration the thickness is constant and is equal to t, therefore the maximum tension is equal to the average tension.

[0031] In summary, one or more embodiments of the present invention may provide at least one of the following benefits, technical effects and advantages: time savings in the design phase: more solid structure, less reinforcements needed; lightening of the frame (elimination of reinforcements and related welds and thinning of thicknesses) with consequent savings on the cost of the product; possibility of using more uniform thicknesses throughout the frame, with consequent improvement in the material purchase and nesting phase (therefore better scrap recovery); elimination of the battery box stop and related welding; possibility of eliminating the safety lock for the battery; savings in terms of logistics for the supplier (warehouse, handling) due to having to manage far fewer codes; possibility of simplifying the articulated door hinges because they no longer have to support the end-of-stroke work; simple and much less expensive solution than reinforcements and thickening distributed throughout the frame: saw-cut commercial bar, laser-cut guide, 2 turned pins; strengthening of the frame itself and improving response to torsional and bending loads with resulting possible lightening of the whole structure.

[0032] In any way it is noted that generally objects such as handles or knobs are examples only and any suitable component may replace them within the scope of the claims. Further, any measurements shown in one, two or three dimensions are indicative and specific to some sample frame with appropriate geometrical modifications, the invention can be applied to any open frame with lateral battery extraction. Yet further, it is clear that any orientation scheme, such a front and rear, left and right, etc. can be reversed or adapted without departing the scope of the claims. Thus, although detailed embodiments have been described, these only serve to provide a better understanding of the invention defined by the independent claims and are not to be seen as limiting.

Claims

1. A frame for an industrial truck, the frame forming part of a battery compartment and comprising:

a back part, a front part opposed to the back part, and a side part connecting the back and the front parts on one side, thereby forming a space for the battery compartment;

a bottom part in mechanical connection with said front, back and side parts and comprising an area for supporting a battery and an opening extending indefinitely away from said side part; and

a bar that removably confines in a closed state said opening on a side opposing said side part and being configured to transfer force between its endpoints on said bottom part,

wherein the bar is provided with an element configured to interact with a door assembly closing said battery compartment on a side opposed to the side part, said element forcing the bar into the closed state upon closing the door,

wherein said element configured to interact with a door assembly is configured to interact slidably with a rail arranged on an inner side of the door assembly.

2. The frame according to claim 1, comprising a hinge toward a first end of said bar and a lock mechanism toward another end of said bar.

3. The frame according to claim 2, wherein said lock mechanism comprises a pin member for blocking a horizontal movement of said bar relative to said bottom part.

4. The frame according to any one of claims 1 to 3, further comprising a vertical lock mechanism blocking a vertical movement of said bar relative to said bottom part and/or back part.

5. The frame according to claim 4, wherein the back part comprises an opening for receiving a distal end of the bar in a closed state and blocking a vertical movement of said bar.

6. The frame according to claim 1, wherein the door assembly comprises a lock mechanism in turn comprising a member that slidably engages with the bar and the bottom part in a closed state.

7. The frame according to claim 6, wherein said slidably engaging member comprises a pin arranged to engage vertically in a hole of said bar and a hole in said bottom part.

Drawing