GB2337030A

GB2337030A - A mobile chassis for an invalid hoist

Info

Publication number: GB2337030A
Application number: GB9806469A
Authority: GB
Inventors: Philip Von Schroeter
Original assignee: Arjo Ltd
Current assignee: Arjo Ltd
Priority date: 1998-03-27
Filing date: 1998-03-27
Publication date: 1999-11-10
Anticipated expiration: 2018-03-27
Also published as: GB2337030B; GB9806469D0

Abstract

The mobile chassis comprises two elongate chassis side members 11 which extend in parallel or substantially parallel spaced apart relationship. Each chassis side member includes a drive wheel 17, a motor 19 for rotating the drive wheel, and a driven wheel 18. The drive wheel is rotatable about an axis extending parallel or substantially parallel to the longitudinal extent of the side member. The driven wheel is rotatable about an axis extending perpendicularly or substantially perpendicularly to the longitudinal extent of the side member. The wheels 18 and 19 of each side member are movable relative to one another between a first position in which the wheels engage one another so that rotation of the drive wheel will cause the driven wheel to rotate to move the chassis along the ground and a second position in which the two wheels are out of engagement with one another.

Description

2337030 -I- A MOBILE CHASSIS This invention relates to a mobile chassis

and, more particularly but not necessarily exclusively, to a mobile chassis for a lifting or transporting device, such as an invalid hoist.

According to one aspect of the invention there is provided a mobile chassis comprising two elongate chassis side members which extend in parallel or substantially parallel spaced relationship, each chassis side member including a drive wheel, a motor for rotating the drive wheel, and a driven wheel, the drive wheel being rotatable about an axis extending parallel or substantially parallel to the longitudinal extent of the side member and the driven wheel being rotatable about an axis extending perpendicularly or substantially perpendicularly to the longitudinal extent of the side member, the wheels of each side member being movable relative to one another between a first position in which the wheels engage one another so that rotation of the drive wheel will cause the driven wheel to rotate to move the chassis along the ground and a second position in which the two wheels are out of engagement with one another.

Conveniently, when the two wheels are in the second position, the driven wheel remains in engagement with the ground so that the chassis can be manually propelled along the ground. Alternatively, when the two wheels are in the second position, only the drive wheel is in engagement with the ground and is rotatable by the motor to drive the chassis along the ground in a direction transverse to the longitudinal extent of the side members.

Preferably, the wheels of each side member are movable relative to one another between a first position in which the wheels engage one another so that rotation of the drive wheel will cause the driven wheel to rotate to move the chassis along the ground, a second position in which the two wheels are out of engagement with one another and the driven wheel remains in engagement with the ground so that the chassis can be manually propelled along the ground, and a third position in which only the drive wheel is in engagement with the ground and is rotatable by the motor to drive the chassis along the ground in a direction transverse to the longitudinal extent of the side members.

Preferably, the chassis has at least two further wheels or castors. These further wheels or castors may be supported by the two chassis side members, respectively.

Preferably, the drive wheel has a knurled, metal, frusto-conical portion engageable with a frusto-conical plastics portion of the driven wheel. In this case, each of the drive and driven wheels preferably also includes a cylindrical or frusto conical plastics ground engageable portion. The plastics material may be polyurethane.

Preferably, the drive wheel is of smaller diameter than the driven wheel.

-3 In one embodiment, the chassis side members are connected together by at least one transverse member. In this case, conveniently, the transverse chassis member is telescopically c x tendi ble/re tractable so that the two chassis side members are movable by the drive wheels towards and away from one another in order to narrow and widen the chassis.

Also, in this one embodiment, preferably, the transverse chassis member supports an upstanding mast provided with a lifting arm for raising a load, such as an invalid. The mast may be telescopic or the lifting arm may be elevatable or pivotable relative to the mast.

In another embodiment, each chassis side member has a mast upstanding therefrom, and each mast has a transverse arm at or adjacent to the upper end thereof, the two transverse arms being pivotable relative to one another about a vertical or substantially vertical axis. In this case, means are preferably provided for keeping the chassis side members parallel or substantially parallel as the transverse arms are pivoted relative to one another.

Preferably, the drive wheel is movable relative to the driven wheel.

Alternatively, the driven wheel may be movable relative to the drive wheel. In either case, the movable wheel may be moved by a linear actuating device acting on a support bearing for the wheel through a guide mechanism which may include a plurality of levers or by a motor pivoting a lever.

-4 The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, wherein:Figure 1 is a perspective view of an invalid hoist including one embodiment of a mobile chassis according to the present invention, Figure 2 is a schematic view of one embodiment of a drive mechanism for the chassis showing the relative positions of the drive and driven wheels of the chassis in three different operating conditions, and Figure 3 is a schematic view of another embodiment of a drive mechanism for the chassis showing the relative positions of the drive and driven wheels in an alternative embodiment, Figure 4 is a perspective view showing another embodiment of a drive mechanism for the chassis, and Figure 5 is a side view of the drive mechanism shown in Figure 4 showing tl 0 the drive and driven wheels of the chassis in three different operating conditions.

Referring firstly to Figure 1 of the drawings, there is shown therein an invalid hoist comprising a mobile chassis 10 having two elongate chassis side members 11 extending in parallel spaced relationship and a transverse member 12 connecting the chassis side members 11 together at or adjacent to one end thereof.

-5 A mast 13 is supported by the transverse member 12 and is upstanding therefrom. The mast 13 is telescopically extendiblelretractable and a lifting arm 14 is connected to the upper end of the mast 13. Alternative methods of raising and lowering the lifting arm 14 may be provided. In some cases, the lifting arm may be raised along the mast by a carriage within the mast. In other cases, the lifting arm may be pivotably connected to the mast for movement by a linear actuator (not shown).

The free end of the lifting arm may be provided with a slina hanger 15 for supporting a full body support sling or it may have two laterally spaced sling attachment points for attaching a sling which passes around the back of a patient below the armpits and which can be used to raise a patient from a seated to a standing position by raising the lifting arm along a generally arcuate path.

Examples of various different forms of lifting device for raising patients can be found in, for example, GB-A-2140773, GB-A-2184706, GB-A-2289457, GB- A2223477 and GB-A-2306941.

The last of the aforementioned specifications describes a hoist having two elongate chassis side members, each of which is provided with an upstanding mast.

A transverse arm projects horizontally, or substantially horizontally, from the upper end of each mast and the two arms are pivotally connected together at their free ends.

Transverse member 12 of the hoist described above with reference to Figure 1 is therefore replaced by the two transverse arms. The chassis members of the hoist in -6the last mentioned specification may be maintained in parallel spaced apart relationship as the arms pivot relative to one another by encoded motors which are housed in respective casings and which pivot the chassis members about respective vertical axes relative to respective masts or by a parallelogram mechanism housed in the arms.

Each end of each elongate side member 11 is provided with a around 0 en ageable wheel or castor 16. Also, each elongate side member 11 provided with 9 a drive wheel 17 and a driven wheel 18 between the two ground engaceable wheels or castors 16. However, it is possible, as an alternative, to provide each side member with only one ground encrageable wheel or castor 16 and with drive and driven wheels 17 and 18 spaced therefrom.

As best shown in Figure 2, each drive wheel is powered by a PMDC motor and gearbox unit 19. The drive wheel 17 is rotatable by the motor 19 about an axis extending parallel to the longitudinal extent of the side member 11. The drive wheel has a frusto-conical portion 20 and a cylindrical, ground engageable portion 21.

The driven wheel 18 is rotatable about a fixed axis extending perpendicularly to the longitudinal extent of the side member 11. The driven wheel has a frusto-conical portion 22 and a cylindrical, ground engageable portion 23, which is of larger diameter than the cylindrical portion 21 of the drive wheel 17.

The frusto-conical portion 20 of the drive wheel 17 has a straight knurled steel surface. The surface of the cylindrical portion 2 1 of the drive wheel 17 and the surfaces of the frusto-conical portion 22 and the cylindrical por-tion 23 of the driven wheel 18 are all formed of plastics material, typically polyurethane.

The axis of the drive wheel 17 is movable in a vertical plane between the three positions shown In Figure 2. This movement of the axis of the drive wheel 17 is achieved by a linear actuator (not shown) wWch pivots toggle levers 24. The levers 24 are pivoted to the side member 11 about a fixed axis 25, are pivotably connected to the linear actuator about axes 26, and are pivotally connected to a support block 28 about axes 27.

The support block 28 serves as a bearing support for the drive wheel 17 and as a support for the motor and gear box urt 19. As the linear actuator pivots the toggle levers 24, the axis of the drive wheel 20 remains horizontal.

Figure 2a shows the drive and driven wheels 17 and 18, respectively, in a first position relative to one another. The cylindrical portion 23 of the driven wheel 18 is in contact with the ground. The frusto-conical portions 20 and 22 of the drive and driven wheel 17 and 18, respectively, are out of engagement with one another.

In this operating condition, the chassis can be propelled manually along the ground by an operator or an attendant.

Figure 2b shows the drive and driven wheels 17 and 18, respectively, in a second position relative to one another. In this position, the cylindrical portion 23 of -8 the driven wheel remains in contact with the ground. The frusto- conical portions 20 and 22 of the drive and driven wheel 17 and 18, respectively, are pressed against one another. The motor and gear box unit 19 can be energised to propel the chassis along the ground. The chassis will be propelled in a straight line if the motors 19 of the two side members 11 are rotated in the same direction (or, if the drive mechanisms are symmetrically arranged, if the motors 19 are rotated in opposite directions), either a forward or a reverse direction. If one motor is powered in one direction and the other motor is powered in an opposite direction (or in a symmetric arrangement, if the motors 19 are rotated in the same direction), the chassis will turn to the left or to the right according to the directions of rotation of the two motors 19.

Figure 2c shows the drive and driven wheels 17 and 18, respectively, in a tffird position relative to one another. In this position, the cylindrical portion 21 of the drive wheel 17 is in contact with the ground. The cylindrical portion 23 of the driven wheel 18 has now been raised out of the contact with the ground. The frusto- coilical portions 20 and 22 of the drive and driven wheels 17 and 18, respectively, ar no longer in contact with one another. In this operating condition, the motors 19 of the two side members 11 can be energised to power the chassis in a sideways direction.

The transverse chassis member 12 can be telescopically extendiblelretractable between two lirnit positions. In this case, the two chassis side members 11 can be moved towards or away from each other in order to widen or narrow the chassis by energising the two motors 19 in opposite directions with the -9drive and driven wheels 17 and 18, respectively, in the operating condition shown in Figure 2c. Limit switches may be provided to de- energise the motors 19 when limit positions are reached.

The chassis can be operated by push buttons on one or two control panels.

For example, one control panel can contain push buttons for driving the chassis forwards and rearwards and for driving the chassis sidewards to the left or to the right. The other control panel can contain push buttons for turning the chassis to the left and to the right and for opening and closing the chassis side members.

Alternatively, the chassis can be operated by two joysticks (not shown), one controlling the linear actuator and the motor 19 of one of the side members 11 and the other controlling the linear actuator and the motor 19 of the other side member 11 - When both joysticks are pressed forwards, the two driven wheels 18 will drive the chassis forwards in a straight line. When both joysticks are moved rearwardly, the two driven wheels 18 will drive the chassis rearwards in a straight line. When one joystick is moved forwards and the other rearwards, the driven wheels 18 will rotate in opposite directions to turn the chassis. When both joysticks are moved to the left or the right, the drive wheels 17 will drive the chassis to the left or the right.

When one joystick is moved to the left and the other to the right, the drive wheels 17 will rotate in opposite directions to extend or retract the chassis.

Figure 3 shows an alternative arrangement for the drive and driven wheels 17' and 18', respectively. In this embodiment, the drive wheel 17' is rotatable by the -10motor and gear box unit 19' about a fixed axis. The driven wheel 18' is movable relative to the drive wheel 17' between three positions. Movement of the driven wheel 18' may be effected once again by a linear actuator operating through guide means, such as a lever arrangement.

In a first position shown at Wa, the driven wheel is in engagement with the ground and the frusto-conical portions of the drive and driven wheels are out of engagement with one another. In a second position shown at 181, the driven wheel remains in contact with the ground but the frusto-corlicaI portion of the driven wheel is pressed against the frusto-conical portion of the drive wheel. In the third position shown at Wc, the driven wheel is raised relative to the drive wheel 17' so that the latter is in engagement with the ground.

Figures 4 and 5 show another alternative drive mechanism for the chassis.

In this embodiment, the drive wheel 17'' is powered by a motor and gear box unit 19''. The motor and gear box unit W' is supported by a support block 28- which also serves as a bearing support for the drive wheel 17".

Two brackets 29 and 30 are connected, respectively, to opposite sides of the support block 28". These brackets are provided with elongate guide slots 31 which receive pins 32 fixed to the side member 11.

The drive wheel 17", together with the support block 28" and the motor and gear box unit 19", are moveable between first, second and third positions by a further motor and gear box unit 33 which is also fixed to the side member 11 and which replaces the linear actuator of the previously described embodiment.

The bracket 29 extends beyond the drive wheel 17" and is pivotally connected at Its free end to a lever 2C. The lever 24- is angularly displaceable by the further motor and gear box unit 33 about an axis 2C.

The drive wheel 17" has a first frusto-conical portion 2C and a second, ground engageable, less steeply tapered frusto-conical portion 21 ". The drive wheel 17'' is rotatable by the motor 19'' about an axis extending substantially parallel to the longitudinal extent of the side member 11. However, when the drive wheel is in its first position (shown in Figure 5a) the axis about which the drive wheel 17'' rotates is inclined slightly upwardly towards the further motor and gear box unit 33. When in its second position (as shown in Figure 5) the axis of the drive wheel 17 '' extends horizontally. When in its third position (shown in Figure 5) the axis of the drive wheel 17'' extends slightly downwardly towards the further motor and gear box unit 33.

The driven wheel 1C is rotatable about a fixed axis extending perpendicularly to the longitudinal extent of the side member 11. The driven wheel has a frusto-conical portion 22'' and a cylindrical, ground engageable portion 23", which is of larger diameter than the larger end of the ground engageable frusto conical portion 2V of the drive wheel 17''.

The frusto-conical portion 2V of the drive wheel 17 has a straight knurled steel surface. The surface of the frusto-conical portion 21 '' of the drive wheel 17and the surfaces of the frusto-conical portion 22'' and the cylindrical portion 23- of the driven wheel 18'' are all formed of plastics material, typically polyurethane.

When the lever 24" is in its position as shown in Figure 5a, the drive and driven wheels 17'' and 18- are out of engagement with one another. The drive wheel 17'' is clear of the ground and the cylindrical portion 23- of the driven wheel 18- is in contact with the ground. In this operating condition, the chassis can be propelled manually along the ground by an operator or an attendant.

When the lever 24'' is displaced angularly to the position shown in Figure 5b, the frusto-conical portion 2V of the drive wheel 17'' is pressed into engagement with the frusto-conical portion 22'' of the driven wheel 1V and the motor and gear box unit 19" can be energised to propel the chassis along the ground.

When the lever 24' is angularly displaced to the position shown in Figure 5c, the frusto-conical portion 2V of the drive wheel 17" is in contact with the ground. The cylindrical portion 23- of the driven wheel 1C has now been raised out of contact with ground. The frusto-conical portions 2V and 22" of the drive and driven wheels 17" and 18'', respectively, are no longer in contact with one another.

In this operating condition, the motors 19" of the two side members 11 can be energised to power the chassis in a sideways direction.

The motors 19'' can also be energised in opposite directions to move the two chassis side members 11 towards or away from each other in order to widen or narrow the chassis.

The embodiments described above are given by way of example only and various modifications will be apparent to persons skilled in the art without departing from the scope of the invention.

Claims

A mobile chassis comprising two elongate chassis side members which extend in parallel or substantially parallel spaced relationship, each chassis side member including a drive wheel, a motor for rotating the drive wheel, and a driven wheel, the drive wheel being rotatable about an axis extending parallel or substantially parallel to the longitudinal extent of the side member and the driven wheel being rotatable about an axis extending perpendicularly or substantially perpendicularly to the longitudinal extent of the side member, the wheels of each side member being movable relative to one another between a first position in which the wheels engage one another so that rotation of the drive wheel will cause the driven wheel to rotate to move the chassis along the ground and a second position in which the two wheels are out of engagement with one another.
2. A mobile chassis as claimed in claim 1, wherein when the two wheels are in the second position, the driven wheel remains in engagement with the ground so that the chassis can be manually propelled along the ground.
3. A mobile chassis as claimed in claim 1, wherein when the two wheels are in the second position, only the drive wheel is in engagement with the ground and is rotatable by the motor to drive the chassis along the ground in a direction transverse to the longitudinal extent of the side members.
4. A mobile chassis as claimed in any one of the preceding claims, wherein -15 the wheels of each side member are movable relative to one another between a first position in which the wheels engage one another so that rotation of the drive wheel will cause the driven wheel to rotate to move the chassis along the ground, a second position in which the two wheels are out of engagement with one another and the driven wheel remains in engagement with the ground so that the chassis can be manually propelled along the ground, and a third position in which only the drive wheel is in engagement with the ground and is rotatable by the motor to drive the chassis along the ground in a direction transverse to the longitudinal extent of the side members.
5. A mobile chassis as claimed in any one of the preceding claims, wherein the chassis has at least two further wheels or castors.
6. A mobile chassis as claimed in any one of the preceding claims, wherein 15 the drive wheel has a knurled, metal, frusto-conical portion engageable with a frustoconical plastics portion of the driven wheel.
7. A mobile chassis as claimed in claims 6, wherein each of the drive and driven wheels also includes a cylindrical or frusto-conical plastics ground engageable 20 portion.
8. A mobile chassis as claimed in any one of the preceding claims, wherein the drive wheel is of smaller diameter than the driven wheel.

-16
9. A mobile chassis as claimed in any one of the preceding claims, wherein the chassis side members are connected together by at least one transverse member.
10. A mobile chassis as claimed in claim 9 when dependent on claim 3 or claim 5 4, wherein the transverse chassis member is telescopically extendibIe/retractable so that the two chassis side members are movable by the drive wheels towards and away from one another in order to narrow and widen the chassis.
11. A mobile chassis as claimed in claim 9 or claim 10, wherein the transverse 10 chassis member supports an upstanding mast provided with a lifting arm for raising a load.
12. A mobile chassis as claimed in any one of claims 1 to 8, wherein each chassis side member has a mast upstanding therefrom, and each mast has a transverse 15 arm at or adjacent to the upper end thereof, the two transverse arms being pivotable relative to one another about a vertical or substantially vertical axis.
13. A mobile chassis as claimed in any one of the preceding claims, wherein the drive wheel is movable relative to the driven wheel.
14. A mobile chassis as claimed in any one of claims 1 to 12, wherein the driven wheel is movable relative to the drive wheel.
A mobile chassis as claimed in claim 13 or claim 14, wherein the movable wheel is moved by a linear actuating device acting on a support bearing for the wheel through a guide mechanism.
16. A mobile chassis substantially as hereinbefore described with reference to 5 the accompanying drawings.
17. An invalid hoist comprising a chassis as claimed in any one of the preceding claims.

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