EP4279438A1

EP4279438A1 - Self-propelled vehicle for transporting a load carrier

Info

Publication number: EP4279438A1
Application number: EP23172726.4A
Authority: EP
Inventors: Bart Johannes Gerardus KAVELAARS
Original assignee: Nipper BV
Current assignee: Nipper BV
Priority date: 2022-05-17
Filing date: 2023-05-11
Publication date: 2023-11-22
Also published as: NL2031891B1

Abstract

A self-propelled vehicle (1) for transporting a load carrier such as a pallet is described. The vehicle comprises two elongated fork bodies (2a, 2b). Each fork body comprises
- an individual elongated chassis part (4a, 4b),
- at least two running wheels (13, 14), at least one of which is connected to the chassis part, swivellably about a steering shaft (15a, 15b, 16a, 16b),
- a drive unit for rotating at least two running wheels,
- an individual loading body with an individual elongated load surface (8a, 8b) for supporting a load carrier thereon, and
- a lifting unit for the vertical displacement of the individual loading body relative to the individual chassis part between a lower position and an upper position.

The chassis parts of the two fork bodies are connected together swivellably about a swivel axis extending in the horizontal direction and perpendicular to the respective longitudinal directions of the fork bodies.

Description

The present invention relates to a self-propelled vehicle for transporting a load carrier such as a pallet. A self-propelled vehicle is described in European publication EP 3426593 B1 . The vehicle has a chassis with two individual parallel, elongated chassis units that are joined together exclusively by means of a load-carrying unit that is U-shaped in top view. Each leg of this U shape, said legs being directed with their free ends backwards in normal use, extends above a chassis unit. Each chassis unit is provided with a lifting unit in order to be able to move the load-carrying unit vertically up and down relative to the chassis unit as well as with two pairs of drivable running wheels. At the location of the rear pair of running wheels of each chassis unit, between the respective chassis unit on the one hand and the load-carrying unit on the other hand, bearing devices are provided, which at the location of a respective bearing device, make a vertical movement of the respective chassis unit possible relative to the load-carrying unit. The intention is that irregularities in a floor over which the vehicle moves may thus be compensated so that the running wheels can remain in contact with the floor and the load-carrying unit itself remains flat. This has the result that if there are irregularities in a floor, it may be said that, seen in side view, there is misalignment between a chassis unit and the load-carrying unit, as can be seen in Fig. 6 of EP 3426593 B1 . For the occurrence of said misalignment, design measures must be taken, and/or there is a question of design limitations. Thus, owing to the aforementioned misalignment, this construction does not lend itself well for application of a lifting unit that comprises a scissor mechanism. The bearing devices in themselves also make the construction complex, wherein in addition the springs of these bearing devices, also on account of the stiffness of the U-shaped load-carrying unit, act against the running wheels maintaining contact with a floor. A further objection arises because maintenance of the vehicle may be complex in practice owing to the fact that the two chassis units are connected to each other via the U-shaped load-carrying unit. In addition, measurements, for example with force sensors, of the load on a chassis unit on account of the weight of a load carrier thereon are influenced by the load on the other chassis unit, on account of the load-carrying unit being U-shaped. Such measurements are used by the control system of the vehicle to prevent, during transport of a load carrier, said load carrier overturning, together with the load carried by the load carrier. For this purpose, the control system will, for example on the basis of the measurements of the load on the two chassis units, lower the transport speed, for example at a bend, and/or will allow bends that are less sharp, which may be a disadvantage for the efficiency with which the vehicles can be employed.
The invention aims to offer an improvement for the aforementioned problems. For this purpose, the invention provides a self-propelled vehicle according to claim 1. The vehicle is configured with two fork bodies, each of which comprises an individual chassis part and an individual loading body. The term "individual" expresses that both the two chassis parts and the two loading bodies at least do not form integral components. Thus, it is possible to approach the two fork bodies individually and for example to replace them. In addition it is thus possible to a greater extent for the two fork bodies to move relative to each other, in particular in order to be able to follow irregularities in a subsurface during movement of the vehicle and wherein contact between running wheels and floor can be ensured to a greater extent. Furthermore, it may thus be ensured easily or at least more easily that the chassis part and the loading body of each fork body remain parallel to each other so that a scissor mechanism that may be employed between a chassis part and a loading body will be loaded less heavily. In addition, the load on one of the two chassis parts will not, or at least to a lesser extent, be affected by the load on the other of the two chassis parts, precisely because of the individual character of the fork bodies. As a result, the vehicle may be controlled more efficiently by the control system thereof.
In an embodiment that is constructionally favourable on account of its potential simplicity, the vehicle comprises at least one axle, preferably a thru axle, with a centre line that coincides with the swivel axis and via which the two fork bodies are connected to each other and are swivellably.
In a further embodiment the vehicle comprises batteries that are coupled to at least one electric motor that forms part of the drive unit and/or to a hydraulic motor that is arranged for supplying hydraulic pressure to at least one hydraulic cylinder that forms part of the lifting unit. The batteries and optionally also the hydraulic motor are preferably housed in a housing that forms part of or at least is connected to a coupling unit such as is discussed hereunder.
In order to prevent the two fork bodies from swivelling excessively relative to each other, so that there would be an unacceptable risk of a load carrier and a load carried by the load carrier overturning, in one embodiment the two fork bodies are joined together swivellably within a range of at most 10 degrees, preferably at most 6 degrees.
In a further embodiment, the vehicle further comprises at least one resistance body, which is active on swivelling of the chassis parts relative to each other from the neutral orientation, to generate a force counteracting said swivelling. The swivelling of the chassis parts relative to each other may thus be damped, giving calmer running behaviour.
In a practical and constructionally favourable embodiment, the vehicle comprises a coupling unit that extends partly directly above the two fork bodies and, relative to which, each of the two chassis parts is connected swivellably about the swivel axis and wherein for each chassis part, a resistance body is provided, each of which, on swivelling of the associated chassis part about the swivel axis relative to the coupling unit from the neutral orientation, is active to generate a force counteracting the swivelling. The coupling unit may also comprise a housing or at least be connected thereto, with for example the aforementioned batteries, electric motor and/or hydraulic motor being located in said housing, wherein the coupling unit including the optional housing then has a relatively stable spatial orientation despite possible swivelling of the two fork bodies relative to each other.
In a further embodiment, the resistance body is arranged so that on swivelling of the chassis parts relative to each other from the neutral orientation, it is loaded in torsion in two opposite directions, and wherein the two chassis parts are connected to each other via the resistance body. In the neutral orientation, the two fork bodies extend parallel to each other.
A resistance body of this kind may in particular be configured as a resistance body whose spring body comprises at least one resilient deformable body part, such as made of rubber, each being confined at least for a part thereof in a chamber that is formed at least partly by a first wall connected rigidly to one chassis part and by a second wall connected rigidly to the other chassis part, said first wall and second wall being located opposite each other, wherein the at least one body part in the neutral position abuts both against the first wall and the second wall of the respective chamber and wherein the distance between the first wall and the second wall changes on account of swivelling of the chassis parts relative to each other about the swivel axis from the neutral position. Said spring body may for example be star-shaped with a number of radial walls, which preferably may each be hollow to make the necessary deformation thereof possible.
As already stated above, the invention lends itself in particular for application with a self-propelled vehicle, each fork body of which comprises a scissor mechanism for keeping the loading body and the chassis part of a fork body parallel to each other, at least to prevent the loading body and the chassis part of a fork body from swivelling relative to each other.
The stability of the self-propelled vehicle may be further improved if the swivel axis is located in top view between two running wheels associated with a fork body which, seen in the longitudinal direction of the fork body, are provided at a distance from each other, wherein efficient use may be made of the length of the vehicle if, seen in the longitudinal direction, the swivel axis is located at a distance from a running wheel that is less than 20% of the distance between the two running wheels associated with a fork body, which, seen in the longitudinal direction of the fork body, are provided at a distance from each other.
In a further embodiment, each fork body comprises at least two sets of two running wheels aligned relative to each other, said sets, seen in the longitudinal direction of the chassis part, being provided at some distance from each other, and of which at least one set, swivellably about a steering shaft, is connected to the chassis part. The steering of the vehicle may then be carried out by driving the two running wheels belonging to a set, at different speeds.
The invention will be explained in more detail hereunder on the basis of the description of two possible embodiments of vehicles according to the invention, referring to the following figures:

Figs. 1a and 1b show, in isometric top view and rear view, a first embodiment of a vehicle according to the invention, wherein Fig. 1b is an exploded view;
Figs. 2a and 2b show, in isometric bottom view and front view, the vehicle according to Figs. 1a and 1b, wherein Fig. 2b is an exploded view;
Figs. 3a and 3b show the vehicle according to the foregoing figures in side view, wherein the vehicle occupies a lower position in Fig. 3a and occupies an upper position in Fig. 3b, wherein a cut-out is made in Fig. 3b for clarity;
Figs. 4a and 4b show, in isometric top view and front view, a second embodiment of a vehicle according to the invention, wherein Fig. 4b is an exploded view of the vehicle;
Figs. 5a and 5b show, in isometric bottom view and front view, the vehicle according to Figs. 4a and 4b, wherein Fig. 5b is an exploded view;
Figs. 6a and 6b show, in isometric view, components of the vehicle according to Figs. 4a to 5b inclusive, wherein Fig. 6b is an exploded view.

Self-propelled vehicle 1 according to Figs. 1a to 3b inclusive comprises two elongated fork bodies 2a, 2b. The fork bodies 2a, 2b extend parallel to each other in the horizontal direction, assuming that the vehicle 1 is on a horizontal floor. The vehicle 1 further comprises a coupling unit 3, via which, in a manner to be described hereunder, the two fork bodies 2a, 2b are connected together. Vehicle 1 will, during normal operation, travel in the direction of travel 10. Terms such as front and rear relate hereunder to this direction of travel 10.
Each fork body 2a, 2b comprises an elongated chassis part 4a, 4b and an elongated load part 5a, 5b. Each fork body 2a, 2b also has a front wheel unit 11a, 11b, each with two running wheels 13, said wheel unit 11a, 11b being provided at the front end of the respective chassis part 4a, 4b, and a rear wheel unit 12a, 12b, each with two running wheels 14, said wheel units 12a, 12b being the same, with respect to configuration, as the front wheel units 11a, 11b, and being provided at a short distance from the rear end of the respective chassis part 4a, 4b. Each of the wheel units 11a, 11b, 12a, 12b is connected, swivelling about a vertical steering shaft 15a, 15b, 16a, 16b, to the associated chassis part 4a, 4b. Per wheel 13, 14, the associated wheel unit 11a, 11b, 12a, 12b is provided with an electric motor, each controlled by an electronic control system of the vehicle 1 not shown in more detail. Thus, vehicle 1 can steer to left or right, for which the wheels 13, 14 belonging to a wheel unit 11a, 11b, 12a, 12b may be driven at different speeds so that the respective wheel unit 11 a, 11b, 12a, 12b will swivel about the respective steering shaft 15a, 15b, 16a, 16b relative to the respective chassis part 4a, 4b. If the wheels 13, 14 belonging to a wheel unit 11a, 11b, 12a, 12b are driven at the same speeds, the wheel unit will move rectilinearly in a direction perpendicular to the rotation axes of the wheels 13, 14.
In side view, each load part 5a, 5b has a square shape with an elongated horizontal part 6a, 6b and an upright part 7a, 7b. Each horizontal part 6a, 6b has the shape of an inverted U, wherein the upper sides of the respective horizontal parts of the U shape form an elongated load surface 8a, 8b for the supporting thereon of a load carrier such as a pallet, crate or roll container. The upright parts 7a, 7b are also each U-shaped in cross-section, said U-shaped space being closed at the top by flanged edges 9a, 9b. Between the upright parts 7a, 7b and the front wheel units 11a, 11b, each of the chassis parts 4a, 4b is provided, in vertical walls thereof located opposite each other, with two bearing holes 19a, 19b aligned with each other.
Between the wheel units 11a, 11b and the wheel units 12a, 12b, the chassis parts 4a, 4b each have a U-shaped cross-section. Between the legs of this U shape, each fork body 2a, 2b is provided with a scissor mechanism 21 (Figs. 3a, 3b), which are provided to allow a chassis part 4a, 4b and the load surface 8a, 8b located above that to extend parallel to each other. Each scissor mechanism 21 is connected at the lower ends of the two, pivoted together, cross arms 21a, 21b thereof to the relevant chassis part 4a, 4b, more specifically to the horizontal part of the aforementioned U shape thereof, wherein the connection to one of the two cross arms 21a, 21b is sliding, so that the lower ends can move towards each other and away from each other respectively during the opening and closing of the scissor mechanism 21. The upper ends of the cross arms 21a, 21b are connected in a comparable manner to the horizontal parts of the inverted U shape of the horizontal parts 6a, 6b of the load parts 5a, 5b.
For moving a load surface 8a, 8b between the lower position according to Fig. 3a and the upper position according to the figure, each fork body 2a, 2b is provided with a hydraulic cylinder 22a, 22b (Fig. 2b), which are mounted within the aforementioned U shape of the upright parts 7a, 7b and whose free ends of the piston rods 23a, 23b engage on flanged edge 9a, 9b. Starting from the lower position, through excitation of the cylinders 22a, 22b, which in operation are controlled for this by the aforementioned control system of vehicle 1, the load parts 5a, 5b will be moved upwards on account of engagement of the piston rods 23a, 23b on the flanged edges 9a, 9b. During this, the scissor mechanisms 21 will be opened until the load parts 5a, 5b reach the upper position according to Fig. 3b, in which a load carrier carried by the load parts 5a, 5b on load surfaces 8a, 8b thereof is free from the surface on which vehicle 1 rests. Then the vehicle 1 can transport the respective load carrier, typically within an industrial space, to a destination. On arrival at the destination, through suitable operation of the hydraulic cylinders 22a, 22b the load parts 5a, 5b can be moved down again to the lower position according to Fig. 3a, wherein the load carrier is released from the load parts 5a and 5b.
Based on the measured hydraulic pressure in the cylinders 22a, 22b, the control system of the vehicle 1 can determine how high the load on each of the fork bodies 2a, 2b is, on account of the weight of the load carrier, with a load thereon, carried by the fork bodies 2a, 2b. The control system can also use this determination to drive the vehicle 1 as efficiently as possible, taking into account safety standards for example by having the travel speed, the size of a bend and braking distances determined by the control system as a function of the measurements.
The coupling unit 3 is an assembled component that also forms the housing for the aforementioned electronic control system of the vehicle 1, not shown in more detail, a hydraulic motor for the cylinders 22a, 22b as well as the batteries with which among other things the aforementioned electric motors of the wheel units 11a, 11b, 12a, 12b and the hydraulic motor may be energized.
Coupling unit 3 comprises a bottom plate 31, on the underside of which four mounting plates 32a, 32b, 32c, 32d are provided, each provided with round holes 33a, 33b, 33c, 33d that are mutually aligned. Between the intermediate mounting plates 32b and 32c, a cylindrical bush 34 is provided, the open ends of which are connected to the holes 33b and 33c. In the assembled state, the holes 33a, 33b, 33c, 33d are also aligned with the bearing holes 19a, 19b, wherein the holes 33a, 33b are located precisely on the opposite sides of the two bearing holes 19b belonging to chassis part 4b and the holes 33c, 33d are located precisely on the opposite sides of the two bearing holes 19a belonging to chassis part 4a.
Coupling unit 3 comprises two thru axles 18a, 18b. Thru axle 18a passes, in the assembled state of vehicle 1, successively through hole 33d, outer bearing hole 19a, inner bearing hole 19a and hole 33c into bush 34. In a comparable manner, thru axle 18b passes successively through hole 33a, outer bearing hole 19b, inner bearing hole 19b and hole 33b into the bush 34. The thru axles 18a, 18b are provided at their outer ends with collars 20a, 20b, in which holes are provided that are aligned with screw holes in the outer mounting plates 32a, 32d so that the thru axles 18a, 18b can be fastened with screws to the mounting plates 32a, 32d. By loosening the respective screws and removing a thru axle 18a, 18b, the associated fork body 2a, 2b can easily be detached from the coupling unit 3 for maintenance and/or replacement. However, it is also conceivable that in an alternative embodiment only one long thru axle is used, which extends at least from hole 33a to hole 33d.
The connection described above between the coupling unit 3 on the one hand and the two fork bodies 2a, 2b on the other hand, more specifically via the two chassis parts 4a, 4b of the two fork bodies 2a, 2b, allow the two fork bodies 2a, 2b to hinge independently of each other about the (common) centre line 41 of bearing holes 19a, 19b and holes 33a-33d. The extent to which said hinging can take place is limited with the aid of rubber spring elements 35a, 35b. Each of these spring elements 35a, 35b is provided at the top with a threaded end that is screwed into screw holes 36a, 36b provided for this purpose in the bottom plate 31. At the bottom, the spring elements 35a, 35b are provided with screw holes that are aligned with holes in respective projecting lips 37a, 37b that form part of the chassis parts 4a, 4b. By means of screws 38a, 38b that project through the aforementioned holes into the lips 37a, 37b, the spring elements 35a, 35b are screwed to the chassis parts 4a, 4b.
If in operation for example a rear wheel assembly 12b is located in a shallow hole in a floor over which vehicle 1 is travelling, fork body 2b will tend to hinge anticlockwise seen in Fig. 2a about centre line 41, so that spring element 35b is pushed in. If the rear wheel assembly 12b is located on a bump, the spring element 35b would be stretched. The spring elements 35a, 35b are typically configured so that they hinge from the neutral position of the associated fork body through an angle of at most 2 degrees, thus allowing a total hinging range of at most 4 degrees.
Figs. 4a to 6b inclusive relate to a second embodiment of a self-propelled vehicle 51 according to the invention. Vehicle 51 has two fork bodies 52a, 52b, which are largely comparable to fork bodies 2a, 2b of vehicle 1 and for this reason are not described in detail here. The two fork bodies 52a, 52b are connected mutually via the chassis parts thereof via a coupling body 53, which is shown in more detail in Figs. 6a, 6b.
The coupling body 53 comprises a male coupling element 54, a female coupling element 55 and a spring body 56. In the assembled state, the coupling element 54 is rigidly connected detachably to the chassis part of fork body 52a and coupling element 55 is rigidly connected detachably to the chassis part of fork body 52b.
Coupling element 54 comprises a cylindrical housing part 57, a cylindrical guide pin 58 extending concentrically within the housing part 57 but also outside the housing part 57 in the direction of coupling element 55, as well as four radial walls 59 extending in the housing part between the housing part 57 and the guide pin 58, which are at an equal distance from each other and between them define four chambers 60.
Coupling element 55 also comprises a cylindrical housing part 61 with the same outside diameter as housing part 57. A cylindrical guide chamber 62, concentric with the housing part, is provided within the housing part 57. The diameter of guide chamber 62 is tailored to that of the cylindrical guide pin 58 so that the guide pin fits therein with a small clearance, wherein swivelling of the guide pin 58 relative to guide chamber 62 about a swivel axis that coincides with centre line 64 is possible. On the side facing coupling element 54, four projecting retaining elements 63 are provided, which extend parallel to each other and to the centre line 64 belonging to the coupling body, at equal distance from each other.
Spring body 56 is made entirely of rubber and comprises a cylindrical part 65 that defines a cylindrical space 66 within it, as well as eight hollow walls 67, which extend, at a regular distance from each other, radially from the cylindrical part 65, and which define radial spaces 68 between pairs of adjacent walls 67.
As will already be evident to a person skilled in the art on the basis of Fig. 6b and the foregoing description, in the assembled state guide pin 58 extends within guide chamber 62. Four pairs of two adjacent walls 67 of the spring body 56 each extend within a chamber 60 of the coupling element 54, wherein a retaining element 63 also extends between the two adjacent walls of said pairs. In its turn, a radial wall 59 also extends between adjacent pairs of two adjacent walls. Thus, walls 67 of the spring element 56 are around and retained between a combination of a radial wall 59 of coupling element 55 and a retaining element 63 of coupling element 55.
On account of the elastic deformability of the walls 67 of the spring element, it is possible for the coupling elements 54 and 55 of coupling body 53 and therefore the associated fork bodies 52a, 52b to swivel to a limited extent, such as already indicated for vehicle 1, about a swivel axis coinciding with centre line 64.
It will be clear to a person skilled in the art that for clarity, in the drawings according to Figs. 4a to 5b inclusive as well as in the foregoing description of vehicle 51, a housing part of vehicle 51, such as may preferably be provided above coupling body 53, for housing components of the vehicle 1 such as a control system, a hydraulic motor and batteries, are missing. Said housing is not essential for a good understanding of the structure and operation of vehicle 51. Said housing may be connected to chassis part 52a and/or 52b without thereby having, in use, a limiting influence on the manner and extent to which the fork bodies 52a and 52b are able to move relative to each other.

Claims

Self-propelled vehicle for transporting a load carrier such as a pallet, comprising two elongated fork bodies extending, at least in a neutral orientation of the vehicle, parallel to each other in the horizontal direction, each comprising
- an individual elongated chassis part,

- at least two running wheels which, seen in the longitudinal direction of the chassis part, are provided at a distance from each other and which are connected rotatably to the chassis part and at least one of which is connected to the chassis part, swivellably about a steering shaft,

- a drive unit for rotating at least two running wheels of the at least two running wheels,

- an individual loading body with an individual elongated load surface for supporting a load carrier thereon,

- a lifting unit for the vertical displacement of the individual loading body relative to the individual chassis part between a lower position and an upper position,
wherein the chassis parts of the two fork bodies are connected to each other swivellably about a swivel axis extending in the horizontal direction and perpendicular to the respective longitudinal directions of the fork bodies.
Self-propelled vehicle according to claim 1, wherein the vehicle comprises at least one axle, preferably a thru axle, with a centre line that coincides with the swivel axis and via which the two fork bodies are connected together swivellably with each other.
Self-propelled vehicle according to claim 1 or 2, wherein the vehicle comprises batteries that are coupled to at least one electric motor that forms part of the drive unit and/or to a hydraulic motor that is arranged for supplying hydraulic pressure to at least one hydraulic cylinder that forms part of the lifting unit.
Self-propelled vehicle according to one of the preceding claims, wherein the two fork bodies are connected together swivellably with each other within a range of at most 10 degrees, preferably at most 6 degrees.
Self-propelled vehicle according to one of the preceding claims, wherein the vehicle further comprises at least one resistance body which, on swivelling of the chassis parts relative to each other from the neutral orientation, is active to generate a force counteracting said swivelling.
Self-propelled vehicle according to claim 5, wherein the vehicle comprises a coupling unit that extends partly directly above the two fork bodies, and relative to which, each of the two chassis parts swivellably about the swivel axis is connected and wherein for each chassis part a resistance body is provided, which in each case, on swivelling of the associated chassis part about the swivel axis relative to the coupling unit from the neutral orientation, is active to generate a force counteracting the swivelling.
Self-propelled vehicle according to claim 5 or 6, wherein the at least one resistance body is arranged so that, on swivelling of the chassis parts relative to each other from the neutral orientation in two opposite directions, it is loaded in torsion and wherein the two chassis parts are connected to each other via the at least one resistance body.
Self-propelled vehicle according to claim 5, 6 or 7, wherein the resistance body comprises at least one resilient deformable body part, such as made of rubber, which are each, at least for a part thereof, confined in a chamber that is formed at least partly by a first wall connected rigidly to one chassis part and by a second wall connected rigidly to the other chassis part, said first wall and second wall being located opposite each other, wherein the at least one body part abuts in the neutral position both against the first wall and the second wall of the respective chamber and wherein the distance between the first wall and the second wall changes on account of swivelling of the chassis parts relative to each other about the swivel axis from the neutral position.
Self-propelled vehicle according to one of the preceding claims, wherein each fork body comprises a scissor mechanism.
Self-propelled vehicle according to one of the preceding claims, wherein the swivel axis is located, in top view between two running wheels associated with a fork body, which seen in the longitudinal direction of the fork body are provided at a distance from each other.
Self-propelled vehicle according to claim 10, wherein, seen in the longitudinal direction, the swivel axis is located at a distance from a running wheel that is less than 20% of the distance between the two running wheels associated with a fork body which, seen in the longitudinal direction of the fork body, are provided at a distance from each other.
Self-propelled vehicle according to one of the preceding claims, wherein each fork body comprises at least two sets of two running wheels aligned relative to each other, said sets, seen in the longitudinal direction of the chassis part, being provided at some distance from each other, and of which at least one set, swivellably about a steering shaft, is connected to the chassis part.