GB2622320A - Vehicle ramp actuator assembly - Google Patents

Abstract

Trailer 1 (fig 1) comprises a chassis 5 with a tailgate, or rear door, 3. The tailgate is pivotally connected to the chassis along bottom edge 3a and is movable between raised and lowered positions, in the lowered position edge 3b rests on the ground, usable as a ramp. Actuator 6, operable to move the tailgate, is connected at end 6a (fig 3) to upper bracket 7 (fig 3), and at end 6b to lower bracket 8, extending below and beyond edge 3a. The lower bracket, or another part of the mechanism, is connected to the chassis by pins 11, 12 through slots 8, 10 which form a limited slide coupling, in an embodiment, end 6b of the actuator is moveable perpendicular to and below the pivot axis when the panel is in the lowered position.

Description

Vehicle Ramp Actuator Assembly The present invention relates to improvements in relation to actuator operated tailgates / ramps on vehicles such as lorries and trailers.

IT is well known in the art to provide a tailgate on a vehicle to enable a storage area of the vehicle to be accessed by moving the tailgate to an open position and then closed off and secured by moving the tailgate to a closed position. A variety of different designs for enabling the operative movement of the tailgate such as roller panels, removeable panels and pivoting panels. Pivoting panels are particularly advantageous firstly because a pivoting design reduces the load which is incurred during the operative movement as the panel remains attached to the vehicle and hence a portion of its weight is carried by the vehicle. Secondly, a pivoting panel which pivots along its bottom edge and hence remains attached to the vehicle along that bottom edge enables the panel, when pivoted down, to operate as a loading / unloading ramp for the vehicle.

References above and hereinafter to a vehicle will be understood to be mean any vehicle, whether self-propelled or otherwise, which has a storage area which includes at least one side which includes a pivotally moveable barrier for controlling access to the storage area, which barrier is pivotally connected to the vehicle along a bottom end so that it may form a ramp access to the storage area. As such, it includes, but is not limited to, vans, lorries, trailers, boats and the like.

IN order to facilitate the operative movement of barrier, such as a tailgate, between its open and closed positions, it is known to provide an actuator that is connected at one end to the vehicle and at the other end to a point on the barrier! tailgate which is offset from the axis of rotation of the barrier The actuator may then be operated to either extend, so as to push the barrier away from the vehicle and hence rotate it into an open position, or contract so as to pull the barrier towards the vehicle and hence rotate the barrier into a closed position. IN a fully extended position, the barrier/tailgate fully rotates so that the free edge of the tailgate, which is opposite to the edge which connects to the vehicle, rests on the ground to provide a ramp access to the storage area of the vehicle. Such actuators may be electrical, hydraulic, manual screw thread or similar. The problem, however, is that the actuators which are suitable for moving such a tailgate have no appreciable compressibility or extendibility, and as a result, once they are actuated into a particular position / length, there is no give in them, so that the tailgate will be locked in that position. However, during loading of the vehicle when the ramp is extended, the increase in weight will cause the vehicle to sag either on the suspension, due to compression of tyres or the like. That will cause an upwards load on the end of the ramp which will urge the ramp to pivot back up towards the vehicle, but the locked actuator will prevent this from happening. As the load increases, so to will the load on the actuator which will eventually cause damage either to the actuator or the brackets by means of which the ends of the actuator are connected to the tailgate and vehicle.

There is accordingly a need for an actuator assembly which overcomes these issues.

According to the present invention, there is provided a vehicle comprising a base having at least one panel which is hingedly connected to the base along a first edge which forms a pivot axis about which the panel is pivotally moveable between a raised position in which it extends upwards from said base, and a lowered position in which a free edge of said panel remote from said first edge rests on a ground surface so that the panel forms a ramp onto the base, an actuator being connected at one end to an outer surface of said panel and at the other end to a projecting end of lower bracket which extends from said base below and beyond said first edge of said panel, the actuator being operable to extend and contract in order to move said panel between said raised and lowered positions, wherein at least one end of the actuator has a limited slide coupling connection to the one of the panel and the lower bracket to which it connects such that said at least one end is linearly moveably relative to said one of the panel and the lower bracket in a direction which is perpendicular to and which passes below said pivot axis of the panel when said panel is in the lowered position.

A vehicle in accordance with the present invention has the advantage that the limited slide coupling, or linear lost motion coupling, which is provided between the actuator and the vehicle means that the end with which the coupling is associated is able to translate relative to its mounting, allowing the actuator to move to a limited degree if loading causes an upwards load on the end of the panel, thereby avoiding damage to the vehicle.

Preferably, said limited slide coupling comprises at least one pin provided on one of the parts of said coupling and at least one elongated slot formed in the other of the parts of the coupling in which said at least one pin engages, said at least one elongated slot extending perpendicularly to said pivot axis, the length of said elongated slot defining the range of linear movement between said end of the actuator and the one of the panel and the lower bracket to which it connects. Such an arrangement provides an effective linear lost coupling in which loading from the actuator during operation thereof can effectively be transmitted from the or each pin to the end of the or each slot.

In a particularly preferred embodiment, there are at least two pins and each pin engages in its own associated slot. This has the advantage of reducing the individual loading on each pin and slot.

Preferably, the direction of the sliding movement of the limited slide / linear lost motion coupling inclines downwards in a direction towards the pivot axis so as to reduce the angle between said direction and the actuator when the panel is in the lowered position.

Preferably, the actuator is connected to a bracket at each end, the connection at each end allowing rotational movement between the actuator and the base or panel to accommodate for the changing angles as the panel moves between its raised and lowered positions.

IN a preferred embodiment, the limited slide coupling is provided between at least one of the brackets and the base or panel, in particular between the lower bracket and the base. This is, then, preferably achieved by means of a pair of pins provided on the base of the vehicle and a pair of slots provided in the lower bracket so that one pin engages in each slot.

The limited slide coupling preferably further includes biasing means, in particular a coil spring, which biases the coupling to a first end which is furthest from the pivot axis. In this way, the maximum range of movement of the end of the actuator towards the pivot axis is ensured upon loading of the vehicle. In the preferred embodiment, the coil spring is connected at one end to the base of the vehicle forward of the forward end of the lower bracket (end which is opposite the end which extends beneath and projects beyond the panel) and at the other end to the lower bracket so as to bias it towards the end of the vehicle opposite said panel.

The vehicle may be a road vehicle such as a lorry, a van or a trailer, and the panel is a tailgate, side door or the like, but it may be any vehicle which has a pivoting access ramp and which may rise and drop during loading due to weight changes or the like. Other vehicles to which the invention may also be applied include boats and planes.

A limited slide coupling as referenced above is intended to cover an connection arrangement which allows the two connected parts to move linearly relative to each other in one direction to a limited degree before engaging with and then being constrained to move with each other when moves beyond the limited range. Such a coupling may also be referred to as a linear lost motion coupling.

In order that the invention may be well understood, there will now be described an embodiment thereof, given by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a perspective view of a trailer as an example of a vehicle to which the present invention may be applied, with the tailgate raised; Figure 2 is the trailer of Figure 1 with the tailgate lowered to form a ramp for accessing the trailer; Figure 3 is a view of a back of a trailer having an actuator assembly according to the invention fastened thereto; Figure 3a is a detailed of an end of the actuator which is attached to the tailgate; Figure 3b is a detail view of an end of the actuator which is attached to the chassis of the trailer; Figure 4 is an exploded view of the bottom of the trailer showing a fastening bracket for securing the actuator to the chassis according to the present invention; Figure 5 is a sectional side view of the trailer of Figure 4 with the tailgate in a raised position; Figure 6 is a sectional side view of the tailgate of Figure 4 with the tailgate in a lowered position with the trailer unloaded; and Figure 7 is a sectional side view of the tailgate of Figure 4 with the tailgate in a lowered position when additional load has been added to the trailer after the lowering of the tailgate.

Referring first to Figure 1, there is shown a trailer 1 as an example of a vehicle with which the present invention may be used. The trailer 1 has chassis 5 with opposing sides 2 and a tailgate or rear door 3 upstanding therefrom which together form an interior chamber 4 within the tailer. The rear door 3 is hindgedly connected to the chassis 5 along its bottom edge 3a such that the rear door 3 pivotally moves about said bottom edge 3a between as raised position (Figure 1) in which it upstands from the chassis 5 so as to close the rear opening of the chamber 4 of the trailer 1, and a lowered position (Figure 2) in which the top 3b of the door 3 is pivoted away from the chamber 4 and engages with the ground on which the trailer is stood so as to form a ramp for entry into and exit from the chamber 4 of the trailer 1.

IN order to facilitate the operation of the rear door of the trailer, an actuator 6 is connected between the chassis 5 and the rear door 3 as shown in Figure 3, which is retracted to pull the door down into its lowered position and extended in order to push the door back up into the closed position. The actuator 6 may be manually operated but is preferably automated such as hydraulic, pneumatic or electrically driven.

More particularly, the actuator 6 is connected, at its upper end 6a, to the outside of the door 3 by an upper bracket 7 which allows pivotal movement of the actuator 6 relative to the door 3 about an axis parallel to the pivot axis between the door 3 and the chassis 5 so as to accommodate for the change in angle between the two parts as the door 3 raises and lowers. The actuator 6 is also connected, at its lower end 6b to the chassis 5 via a lower bracket 8 which extends rearward from the back of the chassis 5 below the hinge line between the door 3 and the chassis 5 as shown in Figure 5. As with the upper bracket 7, the connection between the lower bracket 8 and the lower end 6b of the actuator 6 is a pivotal connection to allow pivoting about an axis parallel to the pivot axis between the door 3 and the chassis 5. Additionally, there is a slide connection between the lower bracket 8 and the chassis 5 so as to enable a limited degree of sliding movement between the lower bracket 8 and the chassis 5 in a longitudinal direction as depicted by Arrow M in Figure 5, thereby allowing the distance by which the lower bracket 8 extends beyond the back of the chassis 5 to vary.

As shown more clearly in Figure 5, the lower bracket 8 has a pair of slots 9, 10 which are spaced apart in, and are elongated in the longitudinal direct along which the lower bracket 8 moves relative to the chassis 5. The lower bracket 8 is secured to the chassis by a pair of pins 11, 12, one associated with each slot 9, 10, which engage though the slots 9, 10 and into the chassis so as to secure the bracket to the chassis whilst the elongated slots 9, 10 allow the lower bracket 8 to slid back and forth within the distance allowed by the length of the slots 9, 10. Biasing means in the form of a coil spring 13 is attached between the forward end of the bracket 8 and the chassis forward of the bracket, the spring 13 biasing the bracket into a forward most position shown in Figures in which the rearward ends of the slots 9, 10 are pressed against the pins 11, 12. From this position, the lower bracket 8 is able to slide rearwards against the biasing force of the spring 13 upon application of sufficient force as described below. Whilst in the illustrated embodiment the biasing means 13 is a coil spring, it will be understood that any other biasing means which urges the bracket towards the front of the vehicle 1 may be used, such as torsion springs or compression material at the rearward end of the slots 9, 10.

The actuator 6 works as follows: When the rear door 3 is in the upright, close position shown in Figure 1, the actuator 6 is full extended and pushes at it lower end 6b against the lower bracket 8 and at its upper end 6a against the upper bracket 7 so as to hold the rear door 3 in its closed position, the length of the actuator 6 being locked until it is operated to open the rear door 6. In this position, the loading from the actuator 6 onto the lower bracket 8 is substantially vertical as shown in Figure 5 and hence substantially perpendicular to the pin and slot coupling between the lower bracket 8 and the chassis 5. Accordingly, the only load on the lower bracket 8 will be from the spring 13 which will act to pull the lower bracket 8 back towards the chassis so the pins 11, 12 engage the rear (actuator) ends of the slots 9, 10.

IN order to lower the door 3, the actuator 6 is operated to start to retract. As the lower bracket 8 is fixed against movement in the vertical direction, the upper bracket 7 is pulled downwards, causing the door 3 to pivot abouts its bottom edge 3b and the door 3 to start to lower. As the angle of the door 3 changes, the actuator 6 will pivot relative to both the lower 8 and upper 7 brackets such that a component of the pull load exerted by the actuator 6 on the lower bracket 8 will be in the direction of the pin and slot coupling which will act to try to pull the lower bracket 8 further out the back of the chassis 5. However, the weight of the door 3 acting on the actuator 6 will be much greater than load from the actuator and hence the lower bracket will remain in its forward most position, shown in Figure 5. This will continue, even after the door 3 passes the horizontal position, until the free edge 3b of the door 3 comes into contact with the ground, whereupon the actuator 6 should be stopped with the lower bracket 8 still in its forward most position as shown in Figure 6.

With a conventional coupling between the actuator 6 and the chassis 5, if the actuator 6 is continued to operate in a manner to lower the door once the door has made contact with the ground, the actuator will continue to pull the upper bracket 7 towards the lower bracket 8, which will have the effect of trying to lift the back of the trailer up, risking damage to the door" the brackets 7, 8 and/or the actuator 6. With the pin and slot coupling of the present invention, such continued operation of the actuator 6 will instead cause the lower bracket 8 to be pull rearwards relative to the chassis 5 against the load of the biasing spring 13, thereby preventing such damage occurring.

Once operation of the actuator 6 is stopped, its length is locked in order to hold the lowered door 3 in position, However, if a load is applied to the trailer, such as when items are added to it, the height of the chassis 5 above the ground will decrease due to sagging on the suspension, compression of the tyres or the like. Such downward movement of the chassis 5 will have the effect of trying to force the free edge 3b of the rear door 3 upwards and hence to increase the angle between the lowered rear door 3 and the chassis 5, which in a prior art arrangement would apply a tensile load on the actuator, brackets and chassis, potentially causing damage to one or more of them. In the present invention however if such a tensile load is applied to the actuator 6, the pin and slot coupling between the lower bracket 8 and the chassis Swill allow the lower bracket 8 to move rearwards relative to the chassis 5, against the loading of the spring 13, as illustrated by the arrows in Figure 8, allowing the free edge 3b of the door 3 to raise relative to the chassis 5, and thereby prevent undesirable loading of the lower bracket 8, rear door 3, upper bracket 7 and actuator 6.

Upon operating the actuator 6 to raise the rear door 3, extension of the actuator 6 will first push the lower bracket 8 forwards relative to the chassis 5 if loading of the trailer has resulted in rearward movement of the lower bracket 8. The rear door 3 will then be caused to pivot back upwards to its raised position, during which motion both the load from the actuator 6 and the weight of the rear door 33 will keep the lower bracket 8 pressed firmly into its forward position.

IT will be understood that whilst the embodiment described above and shown effects the invention by provision of the slot and pin coupling between the lower bracket 8 and the chassis 5 to allow a limited slide coupling therebetween which allows a limited rearward movement of the lower bracket 8, and hence the actuator 6, relative to the chassis 5 to accommodate for lifting of the rear door, the important aspect of the invention is the ability of the actuator 3 to perform either limited longitudinal rearward sliding movement relative to chassis or limited longitudinal forward sliding movement relative to the lowered rear door 3 to accommodate the lifting of the rear door when the trailer is loaded, and this can be achieved by other mechanisms within the scope of the invention. For example, the lower bracket 8 may be fixedly attached to the chassis 5 and the upper bracket 7 may have a pin and slot type coupling to the rear door 3 which allows a limited range of sliding movement between the upper bracket 7 and the rear door 6 in a direction which is perpendicular to and intersects the pivot axis of the door 3. Although when starting the opening movement of the rear door 3 the upper bracket 7 will initially be pulled down to the bottom of the slot and pin coupling, the weight of the rear door 3 will cause it to move back up to a position remote from the bottom edge 3b of the door 3, so that once the door 3 is fully lowered, the door 3 can move relative to the upper bracket 7 within the range allowed by the pin and slot arrangement to accommodate for movement of the rear door under loading of the vehicle as described above. Biasing means may then be associated with the upper bracket to bias it to the end of the slot and pin arrangement remote from the pivot axis of the rear door 3 in the same manner as described above in relation to the primary embodiment.

Furthermore, the slide coupling may instead be arranged between one end of the actuator 6 and the bracket to which it attaches, in which case the bracket will then be fixedly attached to the trailer.

The slide coupling may even be provided at both ends of the actuator, again either between the brackets and the vehicle or between the ends of the actuator and the brackets.

The slide coupling between the parts is described above as being a pin and slot arrangement, but it will be understood that the provision of the pins and slots on the parts may be reversed or even mixed, so that, for example, the lower bracket may be provided with a pair of pins and the chassis a pair of slots, or the bracket may be provided with a pin and a slot and the chassis with a complementary slot and pin.

Other sliding mechanisms which allow limited sliding movement between parts may also be used to achieve the required linear lost coupling arrangements(s).

Claims (10)

1. Claims 1. A vehicle comprising a base having at least one panel which is hingedly connected to the base along a first edge which forms a pivot axis about which the panel is pivotally moveable between a raised position in which it extends upwards from said base, and a lowered position in which a free edge of said panel remote from said first edge rests on a ground surface so that the panel forms a ramp onto the base, an actuator being connected at one end to an outer surface of said panel and at the other end to a projecting end of lower bracket which extends from said base below and beyond said first edge of said panel, the actuator being operable to extend and contract in order to move said panel between said raised and lowered positions, wherein at least one end of the actuator has a limited slide coupling connection to the one of the panel and the lower bracket to which it connects such that said at least one end is linearly moveably relative to said one of the panel and the lower bracket in a direction which is perpendicular to and which passes below said pivot axis of the panel when said panel is in the lowered position.
2. 2. A vehicle according to claim 1, wherein said limited slide coupling comprises at least one pin provided on one part of said coupling and at least one elongated slot formed in another part of the coupling in which said at least one pin engages, said at least one elongated slot extending perpendicularly to said pivot axis, the length of said elongated slot defining the range of linear movement between said end of the actuator and the one of the panel and the lower bracket to which it connects.
3. 3. A vehicle according to claim 2, wherein the limited slide coupling comprises a pair of pins, each pin having an associated slot in which it engages so as to be slideably moveable therealong.
4. 4. A vehicle according to any of the preceding claims, wherein said limited slide couple allows sliding movement in a direction which is inclined downwards towards the pivot axis.
5. 5. A vehicle according to any of the preceding claims, wherein the one end of the actuator is connected to an upper bracket which is connected to the outer side of the panel.
6. 6. A vehicle according to claim 5, wherein at least one of the upper bracket and the lower bracket is connected to the respective panel and base by means of said limited slide coupling.
7. 7. A vehicle according to claim 6, wherein said lower bracket is connected to the base of the vehicle by means of said limited slide coupling comprising at least one slot on one of the lower bracket and the base and at least one complementary engaging pin provided on the other of the lower bracket and the base.
8. 8. A vehicle according to any of the preceding claims, wherein the limited slide coupling further comprising biasing means which biases the coupling to a first end which is furthest from the pivot axis.
9. 9. A vehicle according to claim 8, wherein said biasing means is a coil spring.
10. 10. A vehicle according to any of the preceding claims, said vehicle being one of a lorry and a trailer and said panel is a tailgate.