GB2489001A

GB2489001A - Lift apparatus for a vehicle

Info

Publication number: GB2489001A
Application number: GB1104268.6A
Authority: GB
Inventors: Adam Beck; Paul Edwards
Original assignee: Passenger Lift Services Ltd
Current assignee: Passenger Lift Services Ltd
Priority date: 2011-03-14
Filing date: 2011-03-14
Publication date: 2012-09-19
Also published as: GB201104268D0; GB2489001A8

Abstract

A lift apparatus for a vehicle comprises a support structure 105 for fixing the apparatus to the vehicle and a lift platform 110 which is movably connected to the support structure 105 via articulated arms 115, 116. The lift platform 110 comprises two pivotally-mounted platform sections (205, 206, Fig. 2a) which are arranged side-by-side in a deployed state and arranged to pivot apart about respective pivoting axes as the platform moves from the deployed state to a stowed state. A locking mechanism (305, 310, Fig 4) is arranged to lock the platform sections together in the deployed state. The invention also includes a lifting apparatus for a vehicle, comprising a lift platform, a fluid actuation system for moving the platform and control means for controlling the actuation system.

Description

LIFT APPARATUS FOR A VEHICLE

The present invention relates to a lift apparatus for a vehicle, which can be stowed for transportation, and which when deployed can be raised and lowered to provide access S to the vehicle.

A vehicle such as an ambulance may be fitted with a lift apparatus. Such an apparatus will generally including a support structure which is fixed to the vehicle, and to which a moveable lift platform is connected. The platform will typically be stowed in the rear of the vehicle for transportation, until it is needed. When needed, the platform will be deployed and then can be lowered so that a patient, for example, can be manoeuvred onto it, and then raised so that the patient can be transferred into the vehicle.

In one type of lift apparatus, the platform extends horizontally from the rear of the vehicle when deployed, and vertically inside the rear of the vehicle when stowed. The platform is divided into two pivoting sections. The sections are positioned next to each other when the platform is deployed, in substantially the same plane, for supporting an item to be loaded into the vehicle. When the lift platform is stowed the sections are pivoted apart, into the rear of the vehicle, to permit access through the lift into the rear of the vehicle.

A hydraulic system is generally used to move the platform, under the control of an electrical control circuit. An operator, such as an ambulance driver, may operate the control circuit via an input device. The input device will usually be fairly simple, having two or four buttons for the operator to deploy and stow the platform, and to lower and raise the platform when it is deployed.

The invention provides a lift apparatus for a vehicle, comprising: a support structure for fixing the apparatus to the vehicle; a lift platform which is movably connected to the support structure and comprises two pivotally-mounted platform sections, the platform being movable between a stowed state for transportation and a deployed state in which the platform can be raised and lowered for providing access to the vehicle, the two platform sections being arranged side-by-side in the deployed state and arranged to pivot apart about respective pivoting axes as the platform moves from the deployed state to the stowed state; and a locking mechanism arranged to lock the platform sections together in the deployed state.

Optionally the locking mechanism comprises: a first locking member which is S movably connected to a first one of the platform sections; and a second locking member provided on the second platform section; wherein the first locking member is movable into engagement with the second locking member, thereby to lock the platform sections together in the deployed state.

Optionally the respective side surfaces of the platform sections are arranged to face each other in the deployed state, and the first locking member is movably connected to the first platform section adjacent to its side surface and is movable in a direction parallel thereto.

The apparatus may further comprise an actuation surface and a lock linkage, wherein the actuation surface is arranged to engage with the lock linkage as the lift moves from the stowed state to the deployed state, thereby to cause the first locking member to move into engagement with the second locking member.

Optionally the lock linkage extends along the side surface of the first platform section and includes an engaging surface arranged to engage the actuation surface.

Optionally the lift platform comprises a rectangular frame, and wherein: the frame comprises an end member and a pair of parallel side members extending from respective ends of the end member; each of the platform sections is pivotally mounted to a respective one of the side members; and the actuation surface is provided on the end member.

Optionally the locking mechanism further comprises a biasing means which is arranged to urge the first locking member out of engagement with the second locking member, thereby to cause the locking mechanism to be unlocked when the lift platform moves from the deployed state to the stowed state.

The invention further provides a lifting apparatus for a vehicle, comprising a lift platform, a fluid actuation system for moving the platform and control means for controlling the actuation system, wherein: the lift platform is movable between a stowed state for transportation and a deployed state in which it can be raised and lowered for providing access to the vehicle; the actuation system comprises a fluid actuator arranged to move the lift platform between the stowed state and the deployed S state, and to raise and lower the lift platform in the deployed state; the actuation system has first and second states which provide different rates of movement of the actuator; and the control means is arranged to select the first state of the actuation system for moving the lift platform between the stowed state and the deployed state (either from the stowed to the deployed state, or from the deployed state to the stowed state, or both), to detect when the lift platform is in the deployed state, and to select the second state of the actuation system for raising and lowering the lift platform if the lift platform is in the deployed state.

The actuator may comprise a hydraulic cylinder, and the actuation system comprises a hydraulic pump and fluid carrying means arranged to carry fluid between the pump and the cylinder.

Optionally the fluid carrying means defines two fluid flow paths, and includes a directional control valve assembly arranged to select the state of the actuation system by selecting which of the fluid flow paths fluid flows through, to the actuator, for example from the pump, or from the actuator, for example to a fluid reservoir. The respective fluid flow paths may provide different respective degrees of restriction of fluid flow. Alternatively the fluid carrying means may define a single flow path having a variable restrictor arranged to vary the degree of restriction in the flow path.

Optionally each of the flow paths has a flow restrictor having a cross sectional area which determines the rate of fluid flow through the respective fluid path, the cross sectional areas of the two flow restrictors being different.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a lift assembly according to an embodiment of the invention in a deployed state; Figures 2a, 2b and 2c are a perspective, end, and top views of a platform of the lift assembly of Figure 1; Figure 3 is a perspective view of part of the platform of Figure 2 in a fully deployed state; S Figure 4 is a perspective view of a part of the platform of Figure 2 in a partially deployed state; Figures Sa and Sb are expanded versions of parts of Figure 4; Figures 6a and 6b are views similar to those of Figures Sa and Sb showing the platform in a fully deployed state; Figure 7 is a diagram of the hydraulic system of the lift assembly of Figure 1; Figure 8 is a side view of the lift assembly of Figure 1 in a deployed and raised state; and Figure 9 is a side view of the assembly of Figure 1 showing it in its raised and lowered states.

Referring to Figure 1, a lift apparatus 100 comprises a support structure 105, for mounting the apparatus 100 to a vehicle (not shown), and a lift platform 110 connected to the support structure 105. The lift platform 110 is movable between a generally horizontal deployed state and a generally vertical stowed state. The following description refers to the lift apparatus 100 as though connected to a vehicle.

The lift platform 110 is connected to the support structure 105 via a pair of parallel, articulated arms 115, 116. The arms 115, 116 are driven by a hydraulic system (described in more detail below) to move the lift platform 110 between the deployed state and the stowed state, and to lower and raise the lift platform 110 in the deployed state. Such arms are known, and will be readily understood by the skilled person

without further description.

Referring to Figures 2a-2c, the lift platform 110 includes a frame 200 to which two platform sections 205, 206 are connected via hinges 210a, 210b. The hinges 210a, 210b allow the platform sections 205, 206 to pivot relative to the frame 200.

The frame 200 consists of an end member 201 and a pair of parallel side members 202, 203 extending one from either end of the end member 201. In the deployed state, the end member 201 will extend approximately parallel to the rear of the vehicle (not shown) and the side members 202, 203 will extend rearward, away from the vehicle, in generally horizontal directions perpendicular to the end member 201. As shown in Figure 2c, the frame 200 defines three sides of a rectangle which is substantially filled by the two platform sections 205, 206 when positioned side-by-side inside the frame 200.

The two platform sections 205, 206 are flat and generally rectangular, each being connected on its outer side 205a, 206a to the inner side of a respective one of the side members 202, 203, via a respective pair of hinges 210a, 210b. Each platform section 205, 206 can therefore pivot relative to the frame 200 about a respective pivot axis that is parallel to the length of the side members 202, 203. In the deployed state, the platform sections 205, 206 are arranged side-by-side in substantially the same horizontal plane, between the side members 202, 203 of the frame 200. In this state, the laterally inner side 205b, 206b of each of the platform sections 205, 206 opposes and is positioned next to the laterally inner side 205b, 206b of the other one of the platform sections 205, 206.

As will be appreciated from Figure 1, each of the platform sections 205, 206 is connected to a respective one of the arms 115, 116 through its own linkage 121, 122.

These linkages 121, 122 are arranged such that movement of the lift platform 110 from the deployed state to the stowed state is transferred via the linkages 121, 122 to the platform sections 205, 206, causing the platform sections 205, 206 to pivot apart, rotating upwards about the hinges 210a, 210b. In the stowed state, the platform sections 205, 206 are positioned next to the arms 115, 116 in vertical, approximately parallel planes.

As will be appreciated from Figure 2a, the inboard ends of the frame side members 202, 203 are rigidly connected together by the frame end member 201, but there is no similar structure at the outboard end of the frame 200 to rigidly connect together the outboard ends of the side members 202, 203, since such a structure would obstruct the outboard end of the lift platform 110. It is desirable for the outboard end of the lift platform 110 to be unobstructed, e.g. to permit a wheelchair or trolley bed to be wheeled onto the lift platform 110. However, since the outboard ends of the side members 202, 203 are not rigidly connected together the platform sections 205, 206 tend to spread, i.e. to move away from each other in the horizontal plane, when the lift platform 110 bears a significant load such as a person in a wheel chair or trolley bed.

In this embodiment the lift apparatus 100 is provided with a locking mechanism for locking the platform sections 205, 206 together in the deployed state. Referring to Figures 3 and 4, the locking mechanism consists of a bolt 305 and a socket 310.

The bolt 305 is formed integrally with a bolt linkage 306, both being formed from a narrow length or bar 307 of metal of a height similar to that of the platform sections 205, 206. The bolt bar 307 fits between the opposed inners sides 205b, 206b of the platform sections 205, 206 in the deployed state. The bolt linkage 306 is slidably connected to the inner side 205b of a first one of the platform sections 205 by pins 315 which extend through slots 320 in the bolt linkage 306, allowing the bolt bar 307 to move forwards and backwards parallel to the centre line of that inner side 205b.

The bolt bar 307 extends along most of the inner side 205b, and is bent through two opposite angles 305a, 305b of about ten degrees at the point where the bolt 305 is joined to the bolt linkage 306 to provide clearance between the inner side 205b and the bolt 305. The bolt 305 forms a relatively small portion of the bolt bar 307,e.g.

less than 10% of the bolt bar's total length. The outboard end of the bolt 305 is tapered (see Figure 6b), so that it may be guided into the socket 310. Because of its tapered shape and its clearance from the first platform section's inner side 205b, the outboard end of the bolt 305 can move reliably into the socket 310 without catching or snagging.

The socket 310 is provided on the laterally inner side 206b of the second platform section 206, near the platform's outboard end. It consists of a metal strip bent through two right angles into a C-shape, the ends of which are fixed to the second platform section's inner side 206b to define a rectangular aperture. The socket 310 is spaced by a distance Dsocket (see Figure 2c) from the inboard end of the inner side 206b, the distance Dsocket being greater than the length of the bolt bar 307 -about 20 mm greater in this embodiment.

Referring to Figures Sa, Sb, 6a and 6b, an actuation surface 500 is formed on the end member 201 of the frame 200, near where the inboard end of the first platform section's inner side 205b is positioned when the lift platform 110 is in the deployed state. In this embodiment the actuation surface 500 is flat, but any suitable cam profile could be provided instead. When the first platform section 205 rotates through the last part of its travel into (or the first part of its travel out of) the deployed state, the actuation surface 500 engages a wheel 505 mounted on the bolt linkage's inboard end. Accordingly, the actuation surface 500 translates a small part of the rotation of the first platform section 205 into linear movement of the bolt linkage 306 and hence of the bolt 305. The dimensions and angle of the flat actuation surface 500 dictate the amount and rate, respectively, of the bolt's displacement.

During movement of the lift platform 110 from the stowed state to the deployed state, over most of this movement the bolt bar 307 is held in a retracted position, as shown in Figures Sa and Sb, by means of a return spring 510. However, over the very last part of this movement, engagement of the actuation surface 500 with the bolt linkage 306 causes the bolt 305 to engage with the socket 310, since moving the lift platform 110 causes the rotation of the two platform sections 205, 206, which causes sufficient displacement of the bolt 305 for an end part thereof to move into the socket 310.

Because the actuation surface 500 is positioned on the end member 201, and because of its proportions, the bolt 305 does not slide into the socket 310 until the lift platform is almost in the deployed state, i.e., not until the two platform sections 205, 206 are substantially side-by-side with their inner sides opposing each other. As a result, the bolt 305 reliably moves into or out of the socket 310 as the two platform sections 205, 206 pivot towards or away from each other, without missing or catching.

Since the bolt's only degree of freedom is perpendicular to the direction in which the platform sections 205, 206 tend to spread under a significant load, the locking mechanism serves to lock the platform sections 205, 206 together in the deployed state.

It will be appreciated that the shape of the two locking members, comprising the bolt 305 and socket 310 in the embodiment described, can be varied in many ways provided that movement of one of the locking members relative to the other can cause it to engage with the other to put the locking mechanism into the locked state. Also the lock actuation mechanism can take different forms. The lock linkage can be any suitable form of mechanical linkage arranged to cause the bolt or other locking member to move as the platforms sections move into the deployed state.

Referring to Figures 7 to 9, a hydraulic system 700 drives the arms 115, 116, and has two states: a first state for moving the lift platform 110 between the deployed state and the stowed state (as shown in Figure 8), and a second state for lowering and raising the lift platform 110 when it is in the deployed state (as shown in Figure 9).

Referring to Figure 7, the hydraulic system 700 comprises a respective single-acting cylinder 705, 706 to drive each of the arms. The cylinders 705, 706 are both connected to one port P of a directional control valve assembly 715. The assembly 715 comprises two solenoid-actuated, normally-closed directional control valves 720, 725, and is operable to connect the port P to either one of two further ports A, B of the directional control valve assembly, to select one of two flow paths 730, 735 through actuation of one or other of the valves 720, 725. The hydraulic system 700 is in the first state if the first flow path 730 is selected by actuating the first valve 720, and in the second state if the second flow path 735 is selected by actuating the second valve 725.

The first flow path 730 connects the port B of the directional control valve assembly 715 via a first restrictor 740 to a reservoir 760. The second flow path 735 connects the port A via a second hydraulic restrictor 750 and a further control valve 755 to the reservoir 760. The further control valve 755 is normally in a one-way state in which it prevents flow toward the reservoir 760 but can allow flow back towards the cylinders 705, 706, but is switchable to an open state in which it allows fluid flow in both directions through it. A manual pump 765 is connected in parallel with the further control valve 755 so that it can pump fluid from the reservoir to the cylinders if the main pump 710 fails.

The second restrictor 750 is fixed, but the first restrictor 740 is variable, and restricts the flow of fluid from the cylinders 705, 706 to a rate lower than the flow-rate in the second flow path 735. In this embodiment the flow rate in the first flow path 730 is approximately 1.2 litres per minute, whereas the flow rate in the second flow path 735 is 2 litres per minute.

The pump 710 is connected via a non-return valve 711 to the first flow path 730.

Therefore a large part of the first flow path 730 and the first direction control valve 720 can also form a pressure line through which fluid can be pumped from the reservoir 760 to the cylinders 705, 706. The further control valve 755 can be closed when the pump 710 is operating to prevent fluid return to the reservoir.

A control circuit 770 is connected to a hand held control module 775, which has two buttons 780, 785 (up' and down') on it, and also to a proximity sensor 790 which is mounted on one of the arms 115, 116 and arranged to detect when the lift platform is in the deployed state, e.g. when the platform 110 is in the horizontal position.

The control circuit 770 is arranged to control the valves 720, 725 in the directional control valve assembly 715, and also the further control valve 755 to open or close the first and second flow paths 730, 735.

In operation, if the lift platform 110 is (fully stowed) in the stowed state and the down' button 785 on the control module is pressed, the control circuit is arranged to open the first control valve 720 to open the first flow path 730, allowing fluid to flow from the cylinders 705, 706 to the reservoir 760 allowing the lift platform 110 to rotate downwards towards the deployed state as shown in Figure 8. The relatively slow flow rate of the first flow path means that the lift platform 110 will rotate downwards reasonably slowly and therefore safely. When the lift platform 110 reaches the deployed state, the proximity sensor 790 sends a signal to the control circuit 770 which then closes the first control valve 720 and opens the second control valve 725 thus closing the first flow path 730 and opening the second flow path 735. As further fluid leaves the cylinders 705, 706 via the second flow path 735, the lift platform 110 is lowered, whilst in its deployed state, from its raised position to a lowered position as shown in Figure 9.

If the up' button 780 is pressed, the control circuit 770 turns on the pump 710 and pumps fluid into the cylinders 705, 706 via the pressure line, which raises lift platform while it is in the deployed state. When the lift platform 110 reaches the top of its travel in the deployed state, pumping further fluid into the cylinders 705, 706 (e.g. by pressing the up button 780) causes the lift platform 110 to start to rotate upwards towards its stowed state. However, because of the geometry of the arms 115, 116 and the relatively large lifting of the platform as it rotates upwards for a relatively small amount of movement of the arms 115, 116, higher fluid pressure is required to do this than to raise the lift platform 110 in the deployed state (for any given load on the lift platform 110, including no load). While the fluid pressure required to raise the lift platform 110 will vary gradually over its range of movement, there is a step change from the pressure required to raise the platform to the top of its travel in the deployed state to the pressure required to start to rotate it upwards into its stowed state. A pressure limiting device is arranged to prevent raising of the lift platform 110 from its deployed state towards the stowed state unless the load on the lift platform 110 is below a predetermined limit. If the lift platform 110 is unloaded, and the up' button 780 continues to be depressed, then the lift platform 110 will be raised up into the stowed position. It will be appreciated that fluid can flow into the cylinders 705, 706 through the second direction control valve 725 whether that valve is in its one-way or two-way (open) state.

Advantageously, this embodiment allows the lift platform 110 to be deployed at a slower and therefore safer speed, without slowing the rate at which the deployed lift platform 110 is lowered and raised, since the flow-rate in the second flow path 735 is approximately one half of that in the first flow path 730 and can be selected for deploying the lift platform 110.

It will be appreciated that various modifications can be made to the hydraulic system described. For example the directional control valve block can be used to determine the difference in flow rates for the two flow paths, for example the two directional control valves within it may have different dimensions. Alternatively the two directional control valves 720, 725 can be replaced by a single three-state valve having a closed state and two open states having different bore sizes and therefore allowing different flow rates. Also the second flow path can be selected for moving the lift platform from the deployed state to the stowed state, either as well as, or instead of, for lowering it from the stowed state to the deployed state.

Claims

CLAIMS1. A lift apparatus for a vehicle, comprising: a support structure for fixing the apparatus to the vehicle; a lift platform which is movably connected to the support structure and comprises two pivotally-mounted platform sections, the platform being movable between a stowed state for transportation and a deployed state in which the platform can be raised and lowered for providing access to the vehicle, the two platform sections being arranged side-by-side in the deployed state and arranged to pivot apart about respective pivoting axes as the platform moves from the deployed state to the stowed state; and a locking mechanism arranged to lock the platform sections together in the deployed state.
2. Apparatus according to claim 1 wherein the locking mechanism comprises: a first locking member which is movably connected to a first one of the platform sections; and a second locking member provided on the second platform section; wherein the first locking member is movable into engagement with the second locking member, thereby to lock the platform sections together in the deployed state.
3. Apparatus according to claim 2 wherein: respective side surfaces of the platform sections are arranged to face each other in the deployed state, and the first locking member is movably connected to the first platform section adjacent to its side surface and is movable in a direction parallel thereto.
4. Apparatus according to claim 2 or claim 3 further comprising an actuation surface and a lock linkage, wherein the actuation surface is arranged to engage with the lock linkage as the lift platform moves from the stowed state to the deployed state, thereby to cause the first locking member to move into engagement with the second locking member.
5. Apparatus according to claim 4 wherein the lock linkage extends along the side surface of the first platform section and includes an engaging surface arranged to engage the actuation surface.
6. Apparatus according to claim 4 or claim 5 wherein the lift platform comprises a rectangular frame, and wherein: the frame comprises an end member and a pair of parallel side members extending from respective ends of the end member; each of the platform sections is pivotally mounted to a respective one of the side members; and the actuation surface is provided on the end member.
7. Apparatus according to any one of claims 2 to 6 wherein the locking mechanism further comprises a biasing means which is arranged to urge the first locking member out of engagement with the second locking member, thereby to cause the locking mechanism to be unlocked when the lift platform moves from the deployed state to the stowed state.
8. A locking mechanism for a lifting apparatus, substantially as described herein with reference to the accompanying drawings.9. A lifting apparatus for a vehicle, comprising a lift platform, a fluid actuation system for moving the platform and control means for controlling the actuation system, wherein: the lift platform is movable between a stowed state for transportation and a deployed state in which it can be raised and lowered for providing access to the vehicle; the actuation system comprises a fluid actuator arranged to move the lift platform between the stowed state and the deployed state, and to raise and lower the lift platform in the deployed state; the actuation system has first and second states which provide different rates of movement of the actuator; and the control means is arranged to select the first state of the actuation system for moving the lift platform between the stowed state and the deployed state, to detect when the lift platform is in the deployed state, and to select the second state of the actuation system for raising and lowering the lift platform if the lift platform is in the deployed state.
9. Apparatus according to claim 8 in which the actuator comprises a hydraulic cylinder, and the actuation system comprises a hydraulic pump and fluid carrying means arranged to carry fluid between the pump and the cylinder.
10. Apparatus according to claim 9 wherein the fluid carrying means defines two fluid flow paths, and includes a directional control valve assembly arranged to select the state of the actuation system by selecting which of the fluid flow paths fluid flows through, to or from the actuator.
11. Apparatus according to claim 10 wherein the respective fluid flow paths provide different respective degrees of restriction of fluid flow.
12. Apparatus according to claim 11 wherein each of the flow paths has a flow restrictor having a cross sectional area which determines the rate of fluid flow through the respective fluid path, the cross sectional areas of the two flow restrictors being different.
13. An actuator for a lifting apparatus, substantially as described herein with reference to Figures 1 to 6 of the accompanying drawings.
14. An actuator for a lifting apparatus, substantially as described herein with reference to Figures 7 to 9 of the accompanying drawings.