WO2008007050A1

WO2008007050A1 - Method and apparatus for braking a wheel

Info

Publication number: WO2008007050A1
Application number: PCT/GB2007/002480
Authority: WO
Inventors: Andrew Gray
Original assignee: Gray Matter (Alpha) Limited
Priority date: 2006-07-10
Filing date: 2007-07-04
Publication date: 2008-01-17
Also published as: GB0613553D0

Abstract

A method and apparatus are disclosed for braking a wheel of a castor. The apparatus includes a brake plate member comprising at least one brake pad and an abutment surface. The apparatus also comprises a trigger member comprising a rotatable trigger arm having an abutment member at an end region thereof. In a non-braking mode of operation the trigger arm is locatable to urge the abutment member against the abutment surface of the brake plate member to thereby support the brake member in a non-engaged position.

Description

METHOD AND APPARATUS FOR BRAKING A WHEEL

The present invention relates to apparatus and a methodology for braking, that is to say partially or fully retarding rotation, of a wheel. In particular, but not exclusively, the present invention relates to a method and apparatus for braking a wheel of a castor of the type which may be provided on a shopping trolley or some other form of vehicle and/or item.

There are many instances in which vehicles or items such as furniture units need to be moved from one location to another. In order to facilitate such movement wheels and other such rolling elements are often utilised and a common type of such rolling element is a castor. A castor includes a wheel supported for rotation on a spindle about an axis between two forks (sometimes referred to as a horn). A common use of such castors is the provision of four such castors at corner regions on a lower surface of a shopping trolley (sometimes referred to as a shopping cart). Typically on such a conveyance four castors are provided although other numbers may be applicable. In some countries all four castors will swivel in relation to the trolley so as to provide a very manoeuvrable vehicle. In other countries one or more, and typically two, of the castors are fixed in orientation. Fixed castors are normally provided to give greater control to a user pushing the cart across a slope which is transverse to a direction of travel. It will be understood that swivel castors are arranged so that there is a distance created between a vertical line of the fixing to the cart and the spindle of the wheel creating a wheel that always trails the direction it is being pushed in. A problem exists in that shopping trolleys or other such items which are highly manoeuvrable by virtue of the castors are often stolen. This is particularly an issue if the castor is secured to a valuable piece of equipment. Shopping trolleys are often not stolen for their intrinsic value but for the sake of convenience. They are, however, costly to replace.

A number of suggestions have been made in the past for providing braking systems to retard rotation of a wheel of a castor such as might be secured to a shopping trolley. Such braking systems help reduce the risk of theft or unauthorised removal. For example, an invention detailed in European Patent No 1101685 has been developed to take advantage of the trailing wheel on a swivel castor and allows a brake to come between the wheel and the ground when the shopping trolley is moved out of an authorised area. Whilst such braking assemblies have proved extremely effective, the methodology has certain disadvantages when applied to fixed castors as in such an instance whilst the wheel can be pushed in one direction to allow a brake to operate, it can be pulled in an opposite direction in which the brake will not deploy between the wheel and ground and thus brake the wheel.

It is to be noted that in certain countries and shopping trolley use sectors there is a high utilisation of fixed castors and as such there is a desire for an effective braking system for fixed castor use which can brake the wheel of the castor regardless of whether the wheel is rolled in a forward or backward direction. Preferably the braking system should also be applicable to swivel type castors.

It is an aim of the present invention to at least partly mitigate the above-mentioned problems.

It is an aim of embodiments of the present invention to provide an apparatus and methodology for braking a wheel of a castor which is effective whether or not the wheel is rolled, due to a unit to which the castor is attached being pushed or pulled, in any direction.

It is an aim of embodiments of the present invention to provide a castor of the type suitable to be deployed on a shopping trolley and which includes a versatile braking system.

According to a first aspect of the present invention there is provided an apparatus for braking a wheel of a castor, comprising: a brake plate member comprising at least one brake pad and an abutment surface; and a trigger member comprising a rotatable trigger arm having an abutment member at an end region thereof; wherein in a non-braking mode of operation the trigger arm is locatable to urge the abutment member against the abutment surface of the brake plate member to thereby support the brake plate member in a non-engaged position.

According to a second aspect of the present invention there is provided a method for braking a wheel of a castor, comprising the steps of: releasing a brake plate member comprising at least one brake pad of a castor from a non-engaged position; via gravitational force, locating the brake plate member into an engaged position; and locating a brake pad between a ground surface and the wheel of the castor.

Embodiments of the present invention provide a braking mechanism for a wheel of a castor which offers bidirectional braking.

Embodiments of the present invention provide a method and apparatus for braking a wheel of a castor which can be utilised in conjunction with ground mounted magnetic elements so that an authorised zone can be defined at a desired region within which castor movement is not impeded. As a castor, and thus a unit to which the castor is secured, is moved outside the authorised zone, rotation of the wheel element of the castor is retarded in a braking motion so as to help prevent unauthorised removal of the castor and attached unit.

Embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

Figure 1 illustrates a side view of a castor secured to a shopping trolley;

Figure 2 illustrates a front view of a castor;

Figure 3 illustrates parts of a brake assembly;

Figure 4 illustrates a first side view of a brake plate;

Figure 5 illustrates a second side view of a brake plate;

Figure 6 illustrates a position of a brake plate in a stage of a braking mode of operation;

Figure 7 illustrates a brake pad braking a wheel in a first direction; and

Figure 8 illustrates a brake pad braking a wheel of a castor in a second direction.

In the drawings like reference numerals refer to like parts. Figure 1 illustrates a castor 10 secured to an underside region of a shopping trolley 11. It is to be understood that embodiments of the present invention are not restricted to the braking of castors secured to shopping trolleys. Rather embodiments of the present invention are broadly applicable to instances where castors including some rolling element between forks is secured either permanently or releasably to an item. The item may be a shopping trolley but may equally be some item of furniture or office equipment or medical equipment which must from time to time be movable but which should be constrained within an authorised area.

As illustrated in Figure 1 the castor 10 includes a securing mechanism 12 which is used to secure the castor to the shopping trolley. Embodiments of the present invention are applicable to castors which are permanently or releasably secured to a shopping trolley and also to castors which once secured have a fixed orientation or swivel. The castor illustrated in Figure 1 is fixedly secured to the shopping trolley so that swivelling motion with respect to the shopping trolley is not permitted.

The castor 10 includes a wheel 13 which provides a rolling element which is arranged to roll on an upper surface 14 of a ground surface. The wheel 13 rotates around a central axis 15 via a spindle and is held between a castor fork 16 (sometimes referred to as a horn).

A housing 17 houses a triggering mechanism which is utilised to deploy a brake plate 18 out of a non-braking position illustrated in Figure 1 into a braking position. Once in a braking position one of the two brake pads 19 will be driven into a braking position in which a brake pad is located between the ground surface 14 and outer surface of the wheel. It is to be understood that each brake pad 19^ 19₂ may be integrally formed with the brake plate 18 or may include one or more separate elements secured to the brake plate 18.

Figure 2 illustrates a front view of the castor illustrated in Figure 1. As illustrated in Figure 2 a wheel 13, which includes a contact surface 20, rotates about an axle axis 15 within two forks 16 of the castor. The brake plate 18 is located within the forks of the castor to one side of the wheel. On the outside of the castor the trigger housing 17 houses working parts of a triggering mechanism which is arranged to maintain the brake plate in a supported position when in a non-braking mode of operation but which will release the braking plate 18 so as to enable the braking plate to drop under gravitational force in a braking mode of operation. In the braking mode of operation if the shopping trolley to which the castor is secured is pushed or pulled, the motion engages a braking pad into a position between the rolling surface 20 of the wheel and ground surface 14, either wholly or in part, which prevents movement of the shopping trolley over the ground surface.

Figure 3 illustrates a cut away view of a portion of the castor in more detail. The brake plate 18 is formed generally from a planer rigid material, such as steel or rigid plastic, and includes a central region 30 from which extends planer ear regions 31. Brake pads 19 are secured to the ears of the brake plate. The brake plate includes an arcuate wall region 32 which includes an outer side wall 33 which forms an abutment surface. The wall extends outwardly from the plate and is preferably integrally formed therewith.

Also extending from the plate are two opposed locating side walls 34 which each provide a respective locating surface 35. The locating walls are formed extending outwardly from the central region 30 of the brake plate and include a dog leg region so that the space between the opposing abutment surfaces 35i, 35₂ is generally triangular in shape. This triangular zone mates with a triangular shape locating pin which extends from the housing 17 in which the triggering mechanism is housed. It will be understood that the locating pin 36 serves to prevent rotation of the brake plate when the brake is not deployed in a non-braking mode of operation. The locating walls and locating pin cooperate so that during a reset mode of operation a user can lift the plate assembly 30 into a reset position with a fairly coarse level of accuracy. The plate may then be dropped from a reasonably central position and the locating pin will be guided into a resting position by virtue of the guide walls. To this end it will be appreciated that a variety of shapes of locating pin 36 and abutment surfaces 35^ 35₂, may be utilised in accordance with embodiments of the present invention.

The brake plate also includes a cut-out region 37 which includes a central region in which a spindle and associated spacer rests (as shown in Figure 3) during a non-braking mode of operation. On either side of this central cut out region are corresponding side regions in which the spindle and spacer are locatable when the brake is in operation. The side regions of the cut-out are provided so as to accommodate for bidirectional braking. During use and in non-braking mode of operation the castor will rest on a ground surface 14 as illustrated in Figure 3. As such gravitational force illustrated by arrow A in Figure 3 will tend to urge the braking place downwardly towards the ground surface. This movement is prevented in the non-braking mode of operation by virtue of a pin 38 which is secured to a rotatable arm 39 located in the triggering housing. The pin 38 abuts against the abutment surface 33 of the brake plate. The abutment forces the surface 33 upwardly so that the surface rests on the pin 38. Downward and rotational motion of the brake plate is thus prevented in the non-braking mode of operation.

Figure 4 illustrates a side view of the brake plate 18 in more detail. The brake plate includes two brake pads 19^ 19₂, a central cut out region 37, an abutment surface 33 provided by an outer side wall of an arcuate wall which extends outwardly from the first side surface 40 of the brake plate and two locking walls which also extend outwardly from the side surface 40 of the brake plate 18.

Figure 5 illustrates a reverse side of the brake plate 18 shown in Figure 4. The plate has a reverse surface 41 which includes ears 31₁, 31₂, to which the respective brake pads are secured.

Figure 6 illustrates a castor in which a brake assembly has been triggered so as to release the brake plate 18. This is achieved by virtue of a sensor located in the housing which detects a magnetic element such as a magnetic strip 60 secured in the ground surface 14 as the wheel is rolled over the ground. For example, as shown in Figure 6, the wheel has moved over the ground surface 14 in a direction of arrow B. As the castor moves over the magnetic element 60, this is sensed by a sensor housed in the triggering housing 17. For example, the sensor may include a magnetic element. When sensed, the sensor determines that the castor has moved from an authorised region Y, illustrated to the right hand side of Figure 6, to a non-authorised region X, illustrated on the left hand side of Figure 6. As such, it is determined that movement of the castor is to be prevented and thus a braking mode of operation is to be initiated. The sensor activates a triggering arm 39 which rotates about a triggering axis 61 so that the triggering arm rotates clockwise. This moves the pin 38, located at a distal region of the triggering arm, downwardly away from the axis of rotation of the wheel. This radially outwardly motion means that the side wall abutment surface 33 of the arcuate wall 32 is no longer supported. As such the gravitational force causes the brake plate 18 to fall in the direction A shown in Figure 3 downwardly. This downward motion moves the whole brake plate together with brake pads downwards into a configuration as illustrated in Figure 6. In this configuration the brake pads are configured so that brake pad tips 62 engage with the surface 14 of the ground. It is to be noted that during this motion the locking pin 36 moves away from the opposed surfaces 35 of the locking walls. As such rotation of the brake plate with respect to the wheel is now no longer precluded.

Figure 7 illustrates a braking position in which a brake pad 1Q₁ is located between the ground surface 14 and rolling surface 20 of the wheel. This arrangement is caused by continued motion of the castor in the direction B illustrated in Figure 6. As such a user continues to urge the shopping trolley to which a castor is secured in a selected direction. The tip 62_! of the brake pad 19i engages with the surface and this causes the brake plate 18 to rotate with respect to the castor and trigger housing. The castor will thus now prove extremely difficult to move.

Figure 8 illustrates the bi-directional or double sided nature of the braking mechanism. If the user moving the shopping trolley to which the castor is secured were now to move the trolley in a reverse direction, in this situation the brake tip 62₂ of the brake pad 19₂ engages with the ground surface and movement in a direction opposite to arrow B illustrated in Figure 6 will cause the contact between the brake pad 19 and ground surface 14 to rotate the plate member about the central axis in the opposite clockwise direction. Thus regardless of a direction of motion, as illustrated in Figures 7 and 8, motion of the wheel of the castor is prevented in a braking mode of operation.

Subsequent to a braking mode of operation, as shown in Figure 7 or 8, the brake may be reset by a user in a convenient manner. This is achieved by lifting the brake plate 30 and levelling the brake plate so that it is in a substantially level configuration, as shown in Figure 3. When the brake plate is released, gravitational force will move the brake plate downwardly and the locating pin and guide walls will duly locate the brake plate at a position ready to be deployed. This process is aided by the spacer around the spindle locating on a lower matching surface of the cut out region 37 in the brake plate.

Embodiments of the present invention thus provide a brake that comes between a wheel and ground and that is located on a plate that rotates around the spindle that secures a wheel to a castor. At least two brake pads are provided so that a castor cannot be pushed either forward or backward after the braking device has been triggered. It will be appreciated that the braking assembly can be utilised for swivel castors, as well as fixed castors, although it will be appreciated that for swivel castors one of the brake pads will typically not be needed. Embodiments of the present invention provide a vehicle braking assembly in which the braking assembly is positively located between protrusions on its surface and corresponding mating is provided on a second and fixed plate. A release system allows the brake with twin brake pads to fall onto the ground but thereafter rotate into a braking position.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

1. Apparatus for braking a wheel of a castor, comprising: a brake plate member comprising at least one brake pad and an abutment surface; and a trigger member comprising a rotatable trigger arm having an abutment member at an end region thereof; wherein in a non-braking mode of operation the trigger arm is locatable to urge the abutment member against the abutment surface of the brake plate member to thereby support the brake plate member in a non-engaged position.

2. The apparatus as claimed in claim 1 , further comprising: the trigger member comprises a release switch arranged to release the trigger arm during a braking mode of operation, said trigger arm being locatable, when released, at a location at which the abutment member is no longer urged against the abutment surface.

3. The apparatus as claimed in claim 2, further comprising: the brake plate member is arranged to fall under gravitational force into an engaged position when the abutment surface is no longer supported by an urging force provided by the abutment member.

4. The apparatus as claimed in any preceding claim further comprising a bidirectional brake assembly.

5. The apparatus as claimed in claim 4, further comprising: the brake plate member comprises at least one brake pad located on each of a forward and backward side of the wheel.

6. The apparatus as claimed in any one of claims 1 to 5, further comprising: each brake pad comprises an arcuate member integrally formed with said plate member.

7. The apparatus as claimed in any one of claims 1 to 5, further comprising: each brake pad comprises an arcuate member secured to said plate member.

8. The apparatus as claimed in any one of claims 1 to 7, further comprising: said abutment surface comprises a side wall of an arcuate wall member extending outwardly from a side of the plate member.

9. The apparatus as claimed in any one of claims 1 to 8, further comprising: said brake plate member comprises a central cut out region through which an axle and associated spacer of the castor extends, said cut out including a middle region in which said axle and spacer is located in said non-braking mode of operation and two side regions on either side of the middle region.

10. The apparatus as claimed in any one of claims 1 to 9, further comprising: said brake plate member further comprises a locating surface arranged to be urged against a locating pin of said trigger member in said non-braking mode of operation to thereby prevent rotation of the brake plate member.

11. The apparatus as claimed in claim 10, further comprising: said locating surface comprises two opposed side walls of respective locating wall members extending outwardly from a side of the brake plate member.

12. The apparatus as claimed in claim 10 or claim 11 , further comprising: said trigger member comprises a locking pin having a triangular cross section.

13. The apparatus as claimed in any one of claims 1 to 12, further comprising: said release switch comprises a magnetic element arranged to release the trigger arm when the wheel is moved over a ground mounted magnetic element.

14. The apparatus as claimed in any preceding claim wherein said castor comprises a castor of a shopping cart.

15. A shopping cart comprising the apparatus as claimed in any one of claims 1 to 14.

16. A castor comprising: a wheel; a fork; and the apparatus as claimed in any one of claims 1 to 14

17. A method for braking a wheel of a castor, comprising the steps of: releasing a brake plate member comprising at least one brake pad of a castor from a non-engaged position; via gravitational force, locating the brake plate member into an engaged position; and locating a brake pad between a ground surface and the wheel of the castor.

18. The method as claimed in claim 16 further comprising the steps of: in a non-braking mode of operation, supporting the brake plate member comprising at least one brake pad in a non-engaged position; moving the wheel over a ground mounted magnetic element; and responsive to the movement releasing a trigger arm in a trigger member of the castor.

19. Apparatus constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

20. A method substantially as hereinbefore described with reference to the accompanying drawings.