Mobile bridge device for loading dock and corresponding implementation method.

Abstract

The invention relates to a mobile bridge device for a loading dock, comprising a bridge plate (11) movable between a raised position, in which it extends substantially vertically, and a loading position, in which it extends substantially horizontally, the plate having a longitudinal hinge edge (111), articulated to a fixed structure and a free longitudinal edge (113), intended to come into contact with the floor of a vehicle to be loaded or unloaded.The device comprises at least one electric actuator (13) controlling the movement of the deck plate (11) between the raised position and the loaded position, and vice versa. The electric actuator (13) comprises a stroke rod (132) whose movement within an actuator body (131) is controlled by drive means. A first end of the electric actuator (13) is fixed to the fixed structure, in the vicinity of a first of the longitudinal edges (11), and a second end (1321) of the actuator, corresponding to a free end of the stroke rod (132), is movable by sliding over a predetermined range of movement relative to a connecting piece (14) fixed to the deck plate (11), mounted in the vicinity of the second of the longitudinal edges. Figure 1A.

Description

Title of the invention: Mobile bridge device for loading dock and corresponding implementation method. 1. Scope of the invention

[0001] The field of the invention is that of equipment for vehicle loading docks, in particular of the type trucks, trailers, utility vehicles, etc., installed in warehouses, stores, storage centers, factories, etc.

[0002] More specifically, the invention relates to bridges installed on such quays, to allow safe movement between the vehicle and the quay, in particular for a forklift or a suitable transshipment device. 2. prior art

[0003] Loading and / or unloading docks are well known. They extend from a storage area, generally covered, and are raised above a traffic area so that the floor of a truck trailer when reversing is substantially at the same level as the dock surface.

[0004] Trucks park in such a way as to position the rear of the trailer as close as possible to the edge of the loading dock. However, a gap usually remains, which can prevent a forklift from passing (the wheels could get stuck in this gap, or even cause an accident). This gap is also dangerous for people working on the site.

[0005] Bridges have therefore been developed to cover this space and create a continuous connection between the dock and the trailer floor. In particular, there are manually operated bridges in the form of plates that are positioned over the space. This approach is simple, but has drawbacks in terms of handling (installation and removal of the plate) and safety (during plate movement or when it is improperly installed).

[0006] A much safer solution has been proposed, in the form of a hinged plate on the platform, movable between an upright position (closed bridge) and a working position (open bridge) by means of a hydraulic or gas spring. The equipment generally includes a metal frame, defining a safety space to prevent the risk of a pedestrian being crushed against the platform (in accordance with standard NF EN349 and INRS recommendations ed6059).

[0007] In the upright position, the hydraulic cylinder holds the deck plate in a vertical position, preventing any outward access by a pedestrian or trolley lift. This position corresponds to the absence of a truck, and helps to avoid the risk of falling.

[0008] When a truck is present, the bridge plate is lowered until it contacts the truck trailer floor, forming a secure bridge between the trailer and the warehouse. Depending on the weight of the forklift and the goods being transferred, the level of the trailer floor, and therefore of the bridge (for the part resting on this floor), may vary. To allow the bridge plate to follow these movements, the hydraulic cylinder is disengaged in the working position.

[0009] This approach is effective in terms of safety, but it is complex, cumbersome, and expensive to implement because it requires hydraulic means to control the hydraulic cylinder. This is all the more crucial since, in many cases, several bridges are installed on the same warehouse.

[0010] There is therefore a need for another solution, guaranteeing similar security, but which is simpler and less expensive, whether for equipping small warehouses that cannot implement such hydraulic devices or warehouses comprising a plurality of bridges. 3. Description of the invention

[0011] This is achieved using a mobile loading dock bridge device, comprising a movable bridge plate between a raised position, in which it extends substantially vertically, and a loading position, in which it extends substantially horizontally, said plate having a longitudinal hinge edge, articulated to a fixed structure and a free longitudinal edge, intended to come into contact with the floor of a vehicle to be loaded or unloaded.

[0012] According to the invention, the device comprises at least one electric actuator controlling the movement of said bridge plate between said raised position and said loading position, and vice versa, said actuator comprising a stroke rod whose movement in an actuator body is controlled by drive means.

[0013] A first end of said cylinder is fixed to said fixed structure, in the vicinity of a first of said longitudinal edges, and a second end of said cylinder, corresponding to a free end of said stroke rod, is mobile in sliding, over a predetermined range of displacement, relative to a connecting piece fixed to said bridge plate, mounted in the vicinity of the second of said longitudinal edges.

[0014] Thus, the invention proposes an effective solution for replacing a hydraulic cylinder with an electric cylinder, by providing a degree of freedom between the cylinder rod and the plate, so that the bridge plate can move freely angularly in the loading position, to absorb the movements due to to the variations imposed by the movement of the trailer floor, particularly when a forklift or similar equipment passes over it.

[0015] In the embodiment described below, the free end of the stroke rod is located in the upper part of the cylinder, in the raised position. However, the mounting of the electric cylinder can be reversed.

[0016] Thus, said connecting piece can be mounted so that, in said loading position, said free end of the stroke rod can move over a range between 10 and 20 cm relative to said connecting piece, so as to allow an angular displacement of said plate in said loading position.

[0017] According to a particular embodiment, said connecting piece forms a cap threaded onto said electric cylinder.

[0018] In this case, the head of the cylinder rod is in contact with the end of this cap to move the plate, but away from this end in the loading position, to allow a stroke without interaction with the cylinder rod.

[0019] According to a particular embodiment, means for retrieving the movement of said bridge plate from said raised position and / or said loading position may be provided.

[0020] This may include, in particular, first means of recall mounted between said first longitudinal edge and said fixed structure, for example in the form of a bungee cord.

[0021] According to one variant, these return means may include second return means mounted between said free end of the stroke rod and said connecting piece.

[0022] According to a particular aspect, the device may include a means of compensating the mass of the plate, for example in the form of a pneumatic cylinder mounted in parallel with the electric cylinder.

[0023] This makes it possible to limit the sizing of the electric cylinder.

[0024] According to a particular aspect, the device may include a lower stop and / or an upper stop, controlling the maximum travel of said plate.

[0025] In particular, said lower stop may be formed by a fixed mechanical stop against which said plate rests.

[0026] Said upper stop is formed by a connecting rod substantially parallel to said cylinder, associated with a locking nut.

[0027] The device of the invention may include means for controlling said drive means, taking into account at least one time delay and / or information delivered by at least one position sensor.

[0028] The invention also relates to a method for controlling a device as described above, including in particular the following steps for transitioning from the upright position to the loading position:

[0029] - actuation of said electric actuator so that it rotates said plate of bridge, until it comes into contact with the floor of a trailer;

[0030] - actuation of said electric actuator so as to move the free end of said stroke rod of said connecting piece, so as to allow movement of said plate in said loading position;

[0031] and, for the transition from the loaded position to the upright position:

[0032] - actuation of said electric cylinder so as to return the free end of said racing rod in contact with said connecting piece;

[0033] - actuation of said electric cylinder so that it causes said plate to rotate of bridge, up to the said upright position.

[0034] According to a particular aspect, said step of actuation of said electric cylinder so as to move the free end of said stroke rod away from said connecting piece and / or said step of actuation of said electric cylinder so as to bring the free end of said stroke rod back into contact with said connecting piece are associated with a time delay, during which access to said bridge plate is not permitted. 4. List of figures

[0035] Other objectives, features and advantages of the technique according to the invention will become apparent from the following description of a particular embodiment, given by way of illustration only and not limitation, and which refers to the accompanying figures, in which:

[0036] [Fig.1A] is a three-quarter view of an example of a device according to the invention, in the raised position;

[0037] [Fig.1B] is a three-quarter view of the device of [Fig.1A], in the loading position;

[0038] [Fig.2A] is a cross-sectional view of the device in the raised position;

[0039] [Fig.2B] is an enlarged partial view of the [Fig.2A] upper part, illustrating the upper part of the cylinder and the associated cap;

[0040] [Fig.3A] is a cross-sectional view of the device in the loading position, with a maximum positive elevation difference;

[0041] [Fig.3B] is an enlarged partial view of [Fig.3A], illustrating the upper part of the cylinder and the associated cap;

[0042] [Fig.4A] is a cross-sectional view of the device in the loading position, with a maximum negative elevation difference;

[0043] [Fig.4B] is an enlarged partial view of [Fig.4A], illustrating the upper part of the cylinder and the associated cap;

[0044] [Fig.5A] is a cross-sectional view of the device in the loading position, in contact with the lower mechanical stop;

[0045] [Fig.5B] is an enlarged partial view of [Fig.5A], illustrating the upper part of the cylinder and the associated cap;

[0046] [Fig.6A] is a cross-sectional view of the device in the loading position, with the cylinder in the retracted position;

[0047] [Fig.6B] is an enlarged partial view of [Fig.6A], illustrating the upper part of the cylinder and the associated cap;

[0048] [Fig.7] is an enlarged partial view of a variant of [Fig.6A], illustrating the part upper part of the cylinder and the associated cap and implementing a spring;

[0049] [Fig.8] is a simplified flowchart illustrating the implementation of the device previous figures. 5. Description of an embodiment

[0050] 5.7 general principle

[0051] The invention proposes an alternative to loading dock bridge devices using hydraulic cylinders, or gas cylinders, and using an electric cylinder.

[0052] It should be noted that this approach does not consist of replacing one type of cylinder with another. On the contrary, if a person skilled in the art had considered this possibility, they would have been immediately dissuaded from using an electric cylinder in such an application.

[0053] Indeed, during the loading or unloading of a truck, the deck plate must move to follow the movements induced by the forklift, the trailer's suspension, and the variations in load. Thus, the trailer lowers when the forklift enters it, and then rises when the forklift exits. The plate must therefore be able to move freely, within a predetermined angular range, to follow the variations in the trailer's height.

[0054] To achieve this, once the plate has reached the loading position, the hydraulic cylinder is disengaged so that it does not oppose the plate's movement. This is not possible with an electric cylinder, which cannot be disengaged. It is positioned in a specific position by an electric motor, which drives a screw that moves a piston rod within the piston body. When the motor is stopped, the rod is in a fixed, predetermined position, which does not allow the necessary movement of the plate. Therefore, the first time a forklift passes over it, the device would be damaged, as the piston would oppose the plate's movement, or the forklift would encounter a step, since the plate would not move even though the trailer's height would have changed.

[0055] The man skilled in the art therefore immediately ruled out the use of an electric jack.

[0056] Despite this initial assumption, the inventors have developed a particular solution allowing the use of a conventional electric piston, while permitting the necessary stroke of the plate in the loading position. To achieve this, they provided a degree of freedom between the upper part of the piston (in this text, the expression "upper part of the piston" refers to the part that is actually at the top when the plate is in the upright position) and the plate. In this way, in the loading position, the piston rod is retracted beyond what is necessary to bring the plate into contact with the trailer, allowing the necessary clearance, as described in more detail later.

[0057] 5.2 particular embodiment

[0058] Figures IA and IB are three-quarter views of an embodiment of a device according to the invention, respectively in the raised position and in the loading position.

[0059] The mobile bridge device comprises a bridge plate 11, the lower longitudinal edge of which (in the raised position of [Fig. IA]) 111 is fixed along a loading platform (not shown). A hinge 112 allows rotational movement of this plate 11 between: - the raised position ([Fig. 1 A]) in which plate 11 extends vertically, or substantially vertically, and closes off access to the platform behind it; - the loading position ([Fig.lB]) in which the plate 11 extends substantially horizontally, its free edge 113, opposite the lower edge 111, resting on the floor of a truck (not shown) to form a bridge between the dock and this floor and allow the transfer of loads from the warehouse dock to the inside of the trailer, and vice versa.

[0060] The device also includes a fixed structure 12, comprising, for example, two blocks 1211 and 1212, supporting stops 1221 and 1222 against which the trailer can rest. The two blocks define a safety gap between the platform and the trailer, in which a person is protected from the risk of being crushed. The structure 12 may also include side barriers 1231 and 1232, reducing the risk of falling outwards when the platform is in the loading position.

[0061] According to the invention, the movement of the plate 11 is therefore ensured by an electric actuator 13, the lower end of which (with reference to [Fig.1A]) is mounted for rotation on an extension 113 extending perpendicularly to the plate, under the joint 112.

[0062] The cylinder 13 conventionally comprises a cylinder body 131 in which a cylinder rod 132 can move, ending with a rod head 1321. The cylinder rod 132 carries or has a screw thread and is driven by an electric motor, not shown, to move relative to the cylinder body 131, and to vary the total length of the cylinder.

[0063] According to the invention, the rod head 1321 is not connected to the plate 11, as is usually the case for hydraulic cylinder devices. In fact, a cap 14 introduces a degree of freedom between this rod head and the plate.

[0064] This cap 14 is presented here in the form of a tubular element closed at one of its ends 141 (bottom of the cap), and overlapping an upper part of the cylinder, comprising the cylinder rod and a portion of the cylinder body. The cap 14 is attached to the plate 11, near its free edge 113, and extends parallel to the plate 11, via a pivot connecting element 17.

[0065] According to one embodiment variant, the position of the cylinder can be reversed, the rod and the cap being in the lower position (in the position of [Fig.1A]) in the vicinity of the joint.

[0066] According to another variant, the cap can be replaced by a guide piece, having for example two slots in which an axis mounted at the level of the rod head, perpendicular to the cylinder, can move.

[0067] The device may also include a means of compensating for the weight of the plate, for example in the form of a pneumatic mass compensation cylinder 19, mounted in parallel with the electric cylinder 13, in order to limit the sizing of the electric cylinder.

[0068] The stem head 1321 is movable, over a predetermined range of displacement D ([Fig. 6B]) of a few centimeters, for example between 5 and 10 cm, relative to the end 141 of the cap, and is not fixed to it. This mobility can, depending on the embodiment, be free or associated with return means, as detailed below.

[0069] As illustrated in [Fig. 2A], which is a cross-sectional view of the device in [Fig. IA], and in the enlarged view in [Fig. 2B], in the raised position: - the cylinder rod 132 is fully extended; - the stem head 1321 is in contact with the bottom 141 of the cap 14.

[0070] A top stop mechanism may be provided, for example in the form of a rod 151 guided in a slide 152, and whose end 1511 comes to rest against a complementary portion of the slide 152, to prevent the plate 11 from tilting towards the platform, beyond its raised position.

[0071] The opening of the plate 11, from the raised position to the loading position, is done by progressively retracting the cylinder rod 132 into the cylinder body 131, i.e. by reducing the overall length of the cylinder, to reach the position illustrated by figures 3A and 4A, and the corresponding enlarged views.

[0072] Means for initiating, or assisting in initiating, movement from the raised position may be provided, for example in the form of elastic means, here a bungee cord 16 extending between a block 1211, 1212 of the fixed structure 12 and the upper part 113 of plate 11, and tending to bring it back towards the loading position.

[0073] The loading position is not an exactly and definitively defined position, angularly: it depends on the height of the trailer floor on which the free end 113 rests, which can vary according to the vehicles and their load.

[0074] Thus, the loading position can vary between a maximum positive slope (Figures 3A and 3B) and a maximum negative slope (Figures 4A and 4B). In all cases, during the movement phase, the head of the cylinder rod is in contact with the upper part of the cap until contact with the trailer floor is detected.

[0075] In the absence of a trailer, the movement of the plate takes place until a mechanical safety stop 51 is reached, as illustrated in figures 5A and 5B.

[0076] In a second step, after the plate has come into contact with the floor of the trailer, the cylinder rod is retracted so that it is no longer in contact with the upper part of the cover, as illustrated by Figures 6A and 6B. This aspect is essential, according to the invention: the cylinder is activated, and the cylinder rod retracted accordingly, but the plate remains stationary, in contact with the floor of the trailer.

[0077] In other words, as illustrated in the simplified flowchart of [Fig.8], the opening process 81 comprises two phases: - a phase 811 of plate movement; - a phase 812 of retraction of the cylinder rod beyond what is necessary for the single movement (delay 1).

[0078] In practice, the actuation of the cylinder rod can be continuous: in the first phase, it causes the movement and then, in the second phase, it ensures the retraction of the cylinder.

[0079] The free end of the travel rod can therefore move over a range here between 10 and 20 cm relative to said connecting piece, so as to allow angular displacement of said plate in the loading position. This retraction allows the plate, once placed in the loading or working position, between -20° and +20° relative to the horizontal, to accept oscillations around the equilibrium position related to the transfer and the mass moving on the plate.

[0080] This angular movement is necessary to absorb the variations in height of the trailer, depending on the loads that are removed and added, and the passage of a forklift or other equipment on the plate and in the trailer.

[0081] In practice, retraction corresponds to a phase during which the rod drive motor continues to be activated, while the rotational movement of the plate is interrupted. A time delay is applied, preventing access to the bridge plate until the retraction phase is complete.

[0082] Symmetrically, for the lifting process 82 of the bridge plate, two phases can be distinguished: a phase 821 of repositioning the cylinder rod until the rod head comes into contact with the end of the cap (delay 2); a phase 822 of plate movement, once the rod head is in contact with the end of the cap.

[0083] Loading and unloading, i.e. access to the point plate, are possible between phases 812 and 821.

[0084] The implementation of an electric actuator, driven by an electric drive motor controlled by control means 110 (computer, programmable logic controller, etc.) housed, for example, in a remote enclosure, makes it possible to manage timings 1 and 2 simply and efficiently, as well as, if necessary, other timings, particularly safety timings, and to implement position sensors (position of the plate, position of the actuator rod, position of the vehicle, etc.) and visual or audible control and alarm signals, such as: red or green lights for access from the platform; red or green lights for the presence of a vehicle; opening or closing of an additional door on the platform; extreme position of the plate;

Claims

Demands

1. A mobile loading dock bridge device comprising a bridge plate (11) movable between a raised position, in which it extends substantially vertically, and a loading position, in which it extends substantially horizontally, said plate having a longitudinal hinged edge (111) articulated to a fixed structure and a free longitudinal edge (113) intended to come into contact with the floor of a vehicle to be loaded or unloaded, characterized in that it comprises at least one electric actuator (13) controlling the movement of said bridge plate (11) between said raised position and said loading position, and vice versa, said electric actuator (13) comprising a stroke rod (132) whose movement in an actuator body (131) is controlled by drive means, a first end of said electric actuator (13) being integral with said fixed structure,in the vicinity of a first of said longitudinal edges (11), and a second end (1321) of said cylinder, corresponding to a free end of said stroke rod (132), being movable in sliding, over a predetermined range of displacement (D), relative to a connecting piece (14) integral with said bridge plate (11), mounted in the vicinity of the second of said longitudinal edges.

2. Device according to claim 1, characterized in that said connecting piece (14) is mounted so that, in said loading position, said free end (1321) of the stroke rod can move over a range between 10 and 20 cm relative to said connecting piece (14), so as to permit an angular displacement of said plate (11) in said loading position.

3. Device according to any one of claims 1 and 2, characterized in that said connecting piece (14) forms a cap threaded onto said electric cylinder (13).

4. Device according to any one of claims 1 to 3, characterized in that it comprises return means (16; 71) enabling the movement of said bridge plate (11) to be initiated from said raised position and / or said loading position.

5. Device according to claim 4, characterized in that it comprises first return means (16) mounted between said first longitudinal edge and said fixed structure.

6. Device according to claim 4 or 5, characterized in that it comprises second return means (71) mounted between said free end (1321) of the stroke rod and said connecting piece (14).

7. Device according to any one of claims 1 to 6, characterized in that it comprises a means for compensating the mass of the plate, for example in the form of a pneumatic cylinder (19) mounted in parallel with the electric cylinder (13).

8. Device according to any one of claims 1 to 7, characterized in that it comprises control means (110) of said drive means, taking into account at least one time delay and / or information delivered by at least one position sensor.

9. A method for controlling a device according to any one of claims 1 to 8, characterized in that it comprises the following steps, for the transition from the upright position to the loading position: - actuation (811) of said electric actuator so as to rotate said deck plate until it comes into contact with the floor of a trailer; - actuation (812) of said electric actuator so as to move the free end of said stroke rod away from said connecting piece, so as to allow movement of said plate in said loading position; and, for the transition from the loading position to the upright position: - actuation (821) of said electric actuator so as to bring the free end of said stroke rod back into contact with said connecting piece; - actuation (822) of said electric actuator so as to rotate said deck plate until it reaches said upright position.

10. A method according to claim 9, characterized in that said actuation step (812) of said electric actuator is such as to move the free end of said stroke rod away from said connecting piece and / or said actuation step (821) of said electric actuator is such as bringing the free end of said racing rod into contact with said connecting piece is associated with a time delay, during which access to said bridge plate is not permitted.

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