GB2536969A

GB2536969A - A door clutch mechanism

Info

Publication number: GB2536969A
Application number: GB1505795.3A
Authority: GB
Inventors: King John
Original assignee: P S V TRANSP SYSTEMS Ltd
Current assignee: P S V TRANSP SYSTEMS Ltd
Priority date: 2015-04-02
Filing date: 2015-04-02
Publication date: 2016-10-05
Also published as: GB201505795D0

Abstract

A clutch mechanism (23, see fig 2) for use with an automatic door operation unit (2) for a vehicle, the clutch mechanism comprising: an input drive 231 element for connection to a drive unit; an output drive element 232 for coupling to a door 3 to drive movement of the door between an open and a closed configuration; and a resilient biasing system 233 to bias the input drive element and the output drive element into engagement such that rotation of the input drive element drives the output element, wherein the engagement is such that: a rotational force greater than a first force in a first direction will cause the input drive element to slip on the output drive element; and a rotational force greater than a second force in a second direction will cause the input drive element to slip on the output drive element, wherein the first force is less than the second force. The input and output drive elements may include one or more recesses (231e, see fig 10) which may have inclines, configured to engage one or more protrusions (232c) to engage with each other.

Description

Ref: A13678GB Title: A door clutch mechanism

Description of Invention

Embodiments of the present invention relate to a door clutch mechanism for use with a vehicle. Embodiments include a vehicle including such a clutch mechanism and a method of fitting a clutch mechanism. Embodiments of the invention also relate to an automatic door operation unit, a drive unit, and a vehicle including the same.

Vehicles are typically provided with one or more doors. In some vehicles these are automatically operated by an automatic door operation unit.

Accordingly, as a result of the actuation of a control, the automatic door operation unit may be configured to open or close the door.

If there is an obstruction to the movement of the door, then the object obstructing the door may be damaged or injured (e.g. if the object is a person or animal, for example) by the door closing.

There is a need, therefore, to provide an automatic door operation unit which has safety systems associated therewith to cease the closing of the door if there is an obstruction.

Such systems have been developed and many such systems are electronic using one or more sensors to detect the presence of an object and to cease the closing of the door accordingly. However, if the electronic system is not operating then there is still a risk of damage or injury.

There is a need, therefore, to provide a mechanical safety system which reduces the risk of damage or injury caused by obstructions to closing doors.

In a vehicle there is also a need to securely hold the door in a closed configuration during movement of the vehicle -e.g. to reduce the risk of the door opening inadvertently and one or more objects (or people) falling through 5 the open door.

There is a need, therefore, to provide a mechanism system which reduces the risk of injury caused by automatic door operation units.

Accordingly, an aspect of the invention provides a clutch mechanism for use with an automatic door operation unit for a vehicle, the clutch mechanism comprising: an input drive element for connection to a drive unit; an output drive element for coupling to a door to drive movement of the door between an open and a closed configuration; and a resilient biasing system to bias the input drive element and the output drive element into engagement such that rotation of the input drive element drives rotation of the output drive element, wherein the engagement is such that: a rotational force greater than a first force in a first direction will cause the input drive element to disengage the output drive element; and a rotational force greater than a second force in a second direction will cause the input drive element to disengage the output drive element, and wherein the first force is less than the second force.

The input drive element may include one or more recesses which are configured to be received by one or more protrusions of the output drive 25 element.

The output drive element may include one or more recesses which are configured to be received by one or more protrusions of the input drive element.

The or each recess may include a first pair of inclined surfaces.

The first pair of inclined surfaces may include a first surface at a first angle with respect to the direction of a biasing force applied by the resilient biasing system and a second surface at a second angle with respect to the direction of the biasing force, the first and second angles being different from each other.

The or each protrusion may include a second pair of inclined surfaces.

The second pair of inclined surfaces may include a first surface at a first angle with respect to the direction of a biasing force applied by the resilient biasing system and a second surface at a second angle with respect to the direction of the biasing force, the first and second angles being different from each other The or each recess may be asymmetric.

The or each protrusion may be asymmetric.

The input drive element may include a mounting member for connection to a drive linkage to drive rotation of the input drive element.

The resilient biasing system may include at least one resilient biasing element.

The clutch mechanism may further comprise an inner shaft member, wherein the input drive element may be tubular and is configured to receive at least 25 part of the inner shaft member, and the inner shaft member may be secured to the output drive element for rotation therewith.

The resilient biasing system may be configured to act against the inner shaft member and a portion of the input drive element.

Another aspect provides an automatic door operation unit including: a clutch mechanism; a drive linkage coupled to the input drive element of the clutch mechanism; and a drive unit which is configured to drive movement of the drive linkage to cause movement of the input drive element.

The automatic door operating unit may further comprise: another clutch mechanism; and another drive linkage coupled to the input drive element of the further clutch mechanism, wherein the drive unit is further configured to drive movement of the other drive linkage to cause movement of the input drive element of the further clutch mechanism.

The drive unit may comprise a pinion which is configured to engage a pair of racks, each rack being associated with a respective one of the drive linkages.

The drive unit may be configured to be connected to an electric motor or a pneumatic/hydraulic actuator to drive movement of the pinion.

Another aspect provides a drive unit for use in an automatic door operation unit.

Another aspect may provide a vehicle including a clutch mechanism.

Another aspect may provide a vehicle including an automatic door operation unit.

Another aspect may provide a vehicle including a drive unit.

Another aspect provides a method of fitting a clutch mechanism to a vehicle including: providing a clutch mechanism; and securing the clutch mechanism to the vehicle.

Another aspect provides a method of fitting an automatic door operating unit to a vehicle including: providing an automatic door operating unit; and securing the automatic door operating unit to the vehicle.

Another aspect provides a method of fitting a drive unit to a vehicle including: providing a drive unit; and securing the drive unit to the vehicle.

Embodiments of the present invention are described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an example vehicle for use with embodiments; Figure 2 shows a pair of doors and an automatic door operation unit of embodiments in a closed configuration; Figure 3 shows a pair of doors and an automatic door operation unit of embodiments in an open configuration; Figure 4 shows an automatic door operation unit of embodiments; Figures 5 and 6 show a resilient biasing member of embodiments; Figures 7 and 8 show parts of an automatic door operation unit of embodiments; Figures 9 to 11 show a clutch mechanism of embodiments; and Figures 12 and 13 show a drive unit of embodiments.

Embodiments of the present invention include a clutch mechanism 23 which may be part of an automatic door operation unit 2.

The automatic door operation unit 2 may be configured to actuate a door 3 between an open and a closed configuration. In some embodiments, the automatic door operation unit 2 is configured to actuate a pair of doors 3 between an open and a closed configuration.

The or each door 3 may be associated with an opening which is at least partially defined by a frame. In the closed configuration, the or each door 3 may at least partially close the opening. In the open configuration, the or each door 3 may allow the passage of one or more objects through the opening (and may be such that the or each door 3 does not substantively obstruct the opening).

In embodiments in which a pair of doors 3 is provided, in the closed 15 configuration two adjacent edges of the doors 3 may abut each other. The opposing edges may abut a frame associated with the or each door 3.

The or each door 3 may be a door of a vehicle 100.

Embodiments of the present invention will be described with reference to the vehicle 100 being a bus (see figure 1). However, it will be appreciated that the vehicle 100 could take many different forms. For example, the vehicle 100 may be a road vehicle (such as a bus, coach, van, minibus, car, or the like) or the vehicle may be a vehicle which is configured to travel on tracks (such as a train or tram) or the vehicle may be a seafaring vehicle (such as a boat, ship, or hovercraft) or the vehicle may be an aircraft (such as an aeroplane or helicopter).

Embodiments of the invention are also described in relation to one or more doors 3 which provide access to an interior of the vehicle 100 from outside the vehicle 100. As will be appreciated, embodiments of the present invention may also be useable in relation to one or more interior doors.

In some embodiments, the automatic door operation unit 2 is located above the or each door 3 and/or a part of the frame; however, other locations are also possible.

The or each door 3 is associated with a respective door shaft 31. Rotation of the door shaft 31 causes movement of the associated door 3 between the open and closed configurations.

Accordingly, the or each door shaft 31 may be coupled to its associated door 3 by a connection arm 32. The connection arm 32 may be configured for rotation with the door shaft 31 to which it is coupled and may be connected by a pivotable connection 33 to the associated door 3.

The or each door shaft 31 may include a resilient mounting member 313 which is configured to engage the door shaft 31 and a part of the frame. The resilient mounting member 313 may include a mounting plate 313a which is configured to be secured to a part of the frame (e.g. by one or more bolts). The mounting plate 313a may carry a resiliently biased bearing unit 313b which is configured to engage an end of the door shaft 31. The resiliently biased bearing unit 313b may comprise a tubular extension 313c which is mounted with respect to the mounting plate 313a. The resiliently biased bearing unit 313b may further comprise a bearing shaft 313d which is partially received within the tubular extension 313c. The bearing shaft 313d may include a radial shelf 313e (which may be circumferential). The resiliently biased bearing unit 313b may further include a resilient biasing member 313f which is configured to bias the radial shelf 313e away from the tubular extension 313c (and may act against both). The a bearing block 313g (which may be tubular) may be mounted on the bearing shaft 313d on a side of the radial shelf 313e which opposes the resilient biasing member 313f. The bearing block 313g may be a resiliently deformable block of material. One or more other bearing elements (such as a nylon washer or nylon liner to the bearing block 313g) may be provided also mounted to the bearing shaft 313d.

When fitted to a door 3, the resilient mounting member 313 may be oriented such that the bearing shaft projects upwardly. An end of the door shaft 31 may define a cup-like formation which is configured to receive at least a portion of one or more of the bearing block 313g, the resilient biasing member 313f, the radial shaft 313e and the bearing shaft 313d, and may receive a part of the tubular extension 313c too, to secure the door shaft 31 to the resilient mounting member 313. The resilient mounting member 313 may, therefore, be used in the mounting of the door shaft 31 to the frame.

The or each door 3 may be mounted on one or more tracks to guide movement of the or each door 3 as the or each door 3 moves between the open and closed configurations. In particular, the or each door 3 may carry one or more rollers which run along the or each track.

The or each track may be configured such that the or each door 3 moves outwardly and to one side during movement from the closed to the open configuration, and inwardly and to the other side during movement from the open to the closed configuration. An outward movement may be a movement such that the or each door 3 moves out of the confines of the frame such that sideways movement is possible. Similarly, an inward movement may be a movement such that the or each door 3 moves into the confines of the frame. In other words, the or each door 3 may be a respective plug door.

The outward/inward and sideways movements of the or each door 3 (as 30 defined by the or each track) may be along a curved path (such that the outward/inward and sideways movement may be at least partially completed simultaneously.

In operation, the or each track may be configured such that a main plane of the or each door 3 in the closed configuration is substantially parallel to the main plane of the or each door 3 in the open configuration and during movement between the two configurations.

Embodiments of the invention will, however, be equally applicable to other 10 forms of door 3 -such as a concertina-type folding door or even a conventional door which rotates about a hinge.

In particular, in relation to the depicted embodiments, the or each door 3 may pivot inwardly such that, in the open configuration, the or each door 3 is substantially within the confines of the vehicle 100 (e.g. with a plane of the or each door 3 generally perpendicular to a plane of the opening).

In some embodiments, a pair of doors 3 is provided. The doors 3 in such embodiments, may open and close substantially in unison (i.e. substantially simultaneously) and the automatic door operation unit 2 may be configured to drive rotation of the door shafts 31 in unison (i.e. substantially simultaneously).

An edge 34 of the or each door 3 includes one or more electronic sensors which are configured to sense an obstruction and to output a signal to a 25 control system for the or each door 3. The control system may cease a movement of the or each door in response to the receipt of the signal.

The one or more electronic sensors may, therefore, form part of an electronic safety system associated with the or each door 3.

Embodiments of the present invention may seek to provide a mechanical safety system (which operates even if the electrical safety system is not working (e.g. because it has been deactivated).

The automatic door operation unit 2 may, therefore, be configured to drive the movement of the or each door 3 between the open and closed configurations. This may be achieved, for example, by driving the or each door shaft 31 in a first rotational direction to move the or each door 3 from the open to the closed configuration and/or by driving the or each door shaft 31 in a second rotational direction to move the or each door 3 from the closed to the open configuration.

The automatic door operation unit 2 may, in some embodiments, include a drive unit 21, a drive linkage 22, and a clutch mechanism 23.

The drive unit 21 is mechanically coupled to the clutch mechanism 23 via the drive linkage 22 such that the drive unit 21 is configured to drive movement of one or more parts of the clutch mechanism 23.

The clutch mechanism 23 may include an input drive element 231 which is configured to engage an output drive element 232 of the clutch mechanism 23.

The input drive element 231 is biased into engagement with the output drive element 232 by a resilient biasing system 233 of the clutch mechanism 23.

The input drive element 231 of the clutch mechanism 23 may be mechanically linked (or may be configured to be mechanically linked) to the drive linkage 22 such that movement of the input drive element 231 may be driven by the drive unit 21 via the drive linkage 22.

The output drive element 232 of the clutch mechanism 23 may be mechanically linked (or more be configured to be mechanically linked) to the door shaft 31 either directly or via one or more other components, such that movement of the output drive element 232 may cause movement of the door shaft 31.

In some embodiments, the input drive element 231 and the output drive element 232 are configured for rotational movement with respect to the frame.

In some embodiments, the axis of rotation of the input drive element 231 is substantially aligned with (and parallel to) the axis of rotation of the output drive element 232. In some embodiments, the axis of rotation of the door shaft 31 may be substantially aligned with (and parallel to) the axis of rotation of the output drive element 232.

The clutch mechanism 23 is configured to transmit movement from the drive unit 21 (via the drive linkage 22) to the door shaft 31 during normal operation. However, in the event of an obstruction, the clutch mechanism 23 is configured to decouple the input drive element 231 and the output drive element 232 such that movement of the input drive element 231 is not transmitted to the output drive element 232.

The drive linkage 22 may comprise a linkage shaft 221 which is configured to be advanced or retreated by the drive unit 21. The movement of the linkage shaft 221 may, therefore, be linear movement or substantially linear movement generally along its longitudinal axis.

The linkage shaft 221 may be coupled to the input drive element 231 and this 25 coupling may be via one or more other components of the drive linkage 22. These one or more other components may include one or more joints and/or one or more extension members.

In some embodiments, in which a pair of doors 3 is provided, the above 30 arrangements -the drive linkage 22 and clutch mechanism 23 -may be provided in relation to each of the doors 3, such that there are two drive linkages 22 and two clutch mechanisms 23. Although two drive units 21 may also be provided -each configured to drive a respective one of the clutch mechanisms 23 via a respective drive linkage 22 -a single drive unit 21 may be provided which is configured to drive both clutch mechanisms 23 via their respective drive linkages 22.

Embodiments of the clutch mechanism 23 are described below.

The input drive element 231 may comprise a tubular member 231a and a mounting member 231b. The mounting member 231b may be configured to couple the drive linkage 22 to the clutch mechanism 23. The mounting member 231b may extend radially from the tubular member 231a. In some embodiments, the mounting member 231b defines a pin aperture 231c which is configured to receive a pin which forms part of the drive linkage 22. The mounting member 231 b may be configured to be pivotably connected to the drive linkage 22 and that pivotable connection may be via the pin and pin aperture 231c.

A first end of the input drive element 231 is configured to engage the output drive element 232. The first end has an annular surface 231d which includes one or more recesses 231e.

In some embodiments, the annular surface 231d is planar.

The one or more recesses 231e, in some embodiments, may be asymmetrical. In some embodiments, the one or more recesses 231e are each defined by two inclined surfaces which form an asymmetrical V-shaped recess. The angle of each of the two inclined surfaces with respect to the annular surface 231d may be different.

A second end of the input drive element 231 opposes the first end across a length of the input drive element 231. In some embodiments, the length of a first input drive element 231 for one door 3 is less than the length of a second input drive element 213 for another door 3.

The second end of the input drive element 231 provides a bearing surface 231f against which at least part of the resilient biasing system 233 is configured to bear.

The output drive element 232 may comprise a tubular member 232a.

A first end of the output drive element 232 is configured to engage the input drive element 231. The first end has an annular surface 232b which includes one or more protrusions 232c. In some embodiments, there are a corresponding number of protrusions 232c as there are recesses 231e. In some embodiments, there are at least as many recesses 231e as there are protrusions 232c (in some embodiments, there are more recesses 231e than there are protrusions 232c).

In some embodiments, there are two recesses 231e and two protrusions 232c.

In some embodiments, there are a plurality of recesses 231e and protrusions 232c which are spaced equally around a circumference of the input drive element 231 and the outpour drive element 232.

In some embodiments, the annular surface 232b is planar.

The one or more protrusions 232c, in some embodiments, may be asymmetrical. In some embodiments, the one or more protrusions 232c are each defined by two inclined surfaces which form an asymmetrical V-shaped protrusion. The angle of each of the two inclined surfaces with respect to the annular surface 232b may be different.

In embodiments, the shape and size of the or each protrusion 232c corresponds with the shape and size of the or each recess 231e, such that the or each protrusion 232c is configured to be received by a respective recess 231e.

A second end of the output drive element 232 opposes the first end across a length of the output drive element 232.

Accordingly, the first ends of the input and output drive elements 231, 232 are configured to engage each other. In embodiments the respective annular surfaces 232b, 231d of the input and output drive elements 231,232 are configured to abut the or each protrusion 232c received in a respective recess 231e.

Rotation of the input drive element 231 may cause rotation of the output drive element 232 due to engagement of the or each protrusion 232c and recess 231e. This may be true of rotation in either direction.

In embodiments, the output drive element 232 is secured for rotation with the door shaft 31 such that rotation of the output drive element 232 causes rotation of the door shaft 31 -which, in turn, moves the or each door 3 between the open and closed configurations.

For example, a keyed portion of the door shaft 31 may engage a correspondingly keyed aperture defined by the output drive element 232 (e.g. at the second end of the output drive element 232). In some embodiments, one or more clamp arrangements are provided to secure the output drive element 232 and door shaft 31 for rotation together.

The resilient biasing system 233 may comprise one or more resilient biasing elements 233a,b such as one or more springs (which may be helical springs).

In some embodiments, the output drive element 232 is coupled to an inner shaft member 311. The inner shaft member 311 is fixed to the output drive element 232 and may extend through an inner cavity of the (tubular) output drive element 232. The inner shaft member 311 is configured such that it also extends through an inner cavity of the (tubular) input drive element 231 such that a distal end of the inner shaft member 311 extends beyond the second end of the input drive element 231. In some embodiments, the inner shaft member 311 extends through at least part of the resilient biasing system 233 (which may be located at the second end of the input drive element 231 in some embodiments).

The distal end of the inner shaft member 311 may be threaded.

A nut or other threaded member 312 may be configured to mate with the threaded distal end of the inner shaft member 311 -the thread of the threaded member 312 may, therefore, correspond with the thread of the distal end of the inner shaft member 311.

The inner shaft member 311 may, in some embodiments, form part of the output drive element 231. In some embodiments, the inner shaft member 311 may form part of the resilient biasing system 233. In some embodiments, the inner shaft member 311 may be an end of the door shaft 31 or may be otherwise connected thereto (for rotation therewith).

A first or outer resilient biasing element 233a of the resilient biasing system 233 may be configured to act against the second end of the input drive element 231 and the inner shaft member 311 to bias the input drive element 231 towards the output drive element 232 (as discussed above) in a direction along a longitudinal axis of the inner shaft member 311. The first resilient biasing element 233a may be configured, at a first end, to abut an abutment member 233c which may be in the form of a plate. The abutment member 233c may be in the form of a disc-like plate. The abutment member 233c may define an aperture which is configured to receive part of the inner shaft member 311. In some embodiments, the abutment member 233c is secured (e.g. welded) to the first resilient biasing element 233a.

A second end of the first resilient biasing element 233a may be configured to bear against the second end of the input drive element 231 (e.g. against an annular bearing surface of the input drive element 231).

A second, or inner, resilient biasing element 233b of the resilient biasing system 233 may be configured to bear against the abutment member 233c and the second end of the input drive element 231. Accordingly, the second resilient biasing element 233b may be located within the confines of the first resilient biasing element 233a.

The first and second resilient biasing elements 233a,b may be sized and shaped (or otherwise configured) to receive at least part of the inner shaft member 311 therein. A central longitudinal axis of the first resilient biasing element 233a may, therefore, be substantially parallel to and aligned with a central longitudinal axis of the second resilient biasing element 233b, and may be substantially parallel to and aligned with a central longitudinal axis of the inner shaft member 311.

Accordingly, the resilient biasing system 233 may be secured in place with respect to the input drive element 231 and the output drive element 232 by insertion of the inner shaft member 311 therethrough (e.g. through the first and second resilient biasing elements233a,b and the abutment member 233c). The inner shaft member 311 and resilient biasing system 233 may be such that the threaded distal end extends beyond the abutment member 233c. As such, the threaded member 312 may be secured to the threaded distal end of the inner shaft member 311 and to bear against the abutment member 233c to hold the resilient biasing system 233 in place.

Accordingly, the resilient biasing system 233 is configured to press the input drive element 231 and output drive element 232 together.

The threaded member 312 may be used to adjust a biasing force applied by input drive element 231 to the output drive element 233. This may be achieved by adjusting the location along a length of the inner shaft member 311 at which the threaded member 312 is located. The closer the threaded member 312 is to the output drive element 232 the greater the biasing force (due to greater compression of the first and/or second resilient biasing element 233a,b).

In operation, rotation of the input drive element 231 causes rotation of the output drive element 233 and so rotation of the door shaft 31, and movement of the or each door 3 between the open and closed configurations. This is a result of the or each protrusion 232c bearing against a surface defining at least part of the or each recess 231e. The input and output drive elements 231 are biased together by the resilient biasing system 233 and the biasing force is sufficient to allow the movement of the door between the open and closed configurations.

If there is an obstruction which inhibits movement of the or each door 3 between the open and closed configurations, then the output drive element 232 may be inhibited from further rotation. A surface defining a part of at least one of the or each recess 231e bears against a surface of at least one of the or each protrusions 232c, and the configuration of the surfaces is such that a force will be applied against the biasing force by continued rotation of the input drive element 231. For example, an inclined surface of the or each recess 231e may be drive along a respective inclined surface of the or each protrusion 232c.

When the force applied by the input drive element 231 to the output drive element 232 is sufficient to overcome the biasing force, then the input drive element 231 will be driven against the biasing force (i.e. away from the output drive element 232).

The or each protrusion 232c will no longer be received by the or each recess 231e and the or each protrusion may bear against the annular surface 231d at the first end of the input drive element 231. Accordingly, rotation of the input drive element 231 no longer drives rotation of the out drive element 232 until at least one of the or each protrusions 232c is again received by a recess of the or each recesses 231e (which may occur as the input drive element 231 rotates with respect to the output drive element 232 -e.g. under control of the drive unit 21 or by manual rotation of the door shaft 31 (e.g. by manual movement of the door 3)). This may only occur when all of the or each protrusions 232c is so received in a respective recess 231e.

The or each protrusion 232c and/or the or each recess 231e are configured such that the rotational force required to overcome the biasing force is greater for rotation in one direction than in another direction.

In other words, the engagement between the input and output driving elements 231,232, is such that a rotational force greater than a first force in a first rotational direction will cause the input drive element 231 to disengage the output drive element 232 (such that rotation of the input drive element 231 does not cause rotation of the output drive element 232); and a rotational force greater than a second force in a second rotational direction will cause the input drive element 231 to disengage the output drive element 232 (such that further rotation of the input drive element 231 does not cause rotation of the output drive element 232), and wherein the first force is less than the second force.

Accordingly, the engagement may be such that two shallow inclined surfaces of the or each recess 231e and protrusion 232c abut during a closing operation to transfer rotation of the input drive element 231 to the output drive element 232 (i.e. movement of the or each door 3 from the open to the closed configuration). Two other surfaces of the or each recess 231e and protrusion 232c may be comparatively steep (with respect to the direction of the biasing force). Accordingly, a force applied to the output drive element 232 stopping or slowing rotation of the output drive element 232, relative to the input drive element 231, will cause the relatively shallow surfaces to pass over each other and the biasing force to be overcome -so that the input and output drive elements 231,232 disengage (although may still be in contact with each other).

The force required on the output drive element 231 may be relatively low because it is the two relatively shallow surfaces which are engaged.

Once the or each door 3 is in the closed configuration, the two steep surfaces must abut during an opening operation to transfer rotation of the input drive element 231 to the output drive element 231 (i.e. movement of the or each door 3 from the closed to the open configuration). If the user has not actuated the drive unit 21 to cause rotation of the input drive element 231, then any manual force on the or each door 3 to open the door 3 would require the steep surface of the output drive element 232 to pass over the steep surface of the input drive element 231-so that the input and output drive elements 231,232 disengage (although may still be in contact with each other). The force required on the output drive element 231 (e.g. via the door 3 or door shaft 31) may be relatively high because it is the two relatively steep surfaces which are engaged.

Thus, in embodiments, the or each door 3 applies only a relatively small force on an obstruction during a closing operation but strongly resists a manual or inadvertent opening operation. Of course, in an emergency a sufficiently large force may be manually applied to open the or each door 3 by overcoming the biasing force.

Accordingly, a relatively high rotational force may be required to cause movement of the output drive element 232 in the first direction (i.e. to open the or each door 3) without movement of the input drive element 231 (i.e. by overcoming the biasing force). The or each door 3 may be, therefore, securely held in the closed configuration. However, a relatively low force in the second direction may be all that is required to overcome the biasing force (and.

This may be achieved by providing the one or more recesses 231e and/or protrusions 232c of asymmetrical form. In particular, the or each recess 231e and the or each protrusion 232c may be defined by two respective inclined surfaces, wherein a first such surface is at a steeper angle with respect to the axis of the biasing force than a second such surface.

The steeper the angled inclined surface of a recess 231e which abuts a correspondingly angled inclined surface of a protrusion 232c during rotation in a first direction, the less of the rotational force is translated into a force in a direction against the biasing force.

The shallower the angled inclined surface of a recess 231e which abuts a correspondingly angled inclined surface of a protrusion 232c during rotation in a second direction, the more of the rotational force is translated into a force in a direction against the biasing force.

Accordingly, in some embodiments, during rotation of the input drive element 231 and output drive element 232 in the first direction, respective first surfaces of the or each recess 231e and protrusion 232c abut each other. In some embodiments, during rotation of the input drive element 231 and output drive element 232 in the second direction, respective second surfaces of the or each recess 231e and protrusion 232c abut each other. The first surfaces are at a steeper angle with respect to the direction of the biasing force than the second surfaces in such embodiments.

Accordingly, the or each clutch mechanism 23 may be configured to disengage the respective input and output drive elements 231,232 to inhibit the transmission of rotational movement therethrough in the event of an obstruction to movement of the door but also to hold the or each door 3 in the closed configuration relatively securely. The rotational force to cause the disengagement of the input and output drive elements 231,232 during movement of the or each door 3 from the open to the closed configuration is larger than the rotational force required to move the door from the closed to the open configuration.

The clutch mechanism 23 of embodiments, therefore, assists in providing an automatic door operation unit 2 which securely closes a door 3 but which does not apply too much force on any obstruction to the movement of the door 3 during closure.

In embodiments, the drive unit 21 is a double rack and pinion drive unit in which one pinion 211 engages two racks 212. A first of the racks 212 is connected to drive movement of a first of the drive linkages 22 and a second of the racks 212 is connected to drive movement of a second of the drive linkages 22. As such the drive unit 21 may be configured to drive the movement of two doors 3.

The pinion 211 may be located between the two racks 212 and may be configured to be driven by an electric motor or a pneumatic actuator or a hydraulic actuator. Accordingly, a housing 213 of the drive unit 21 may be configured to be secured to a housing for an electric motor or a pneumatic actuator or a hydraulic actuator, with an operative part of the motor or actuator being coupled to the pinion 211 to drive the rotation thereof. In some embodiments, the same drive unit 21 may be connectable to an electric motor and/or an actuator (which may be a hydraulic or a pneumatic actuator).

As such the same drive unit 21 may be used in relation to vehicles 100 with different internal systems (e.g. some vehicles 100 may not have an accessible hydraulic or pneumatic system). In some embodiments, the same drive unit 21 can, therefore, be converted from using a hydraulic or pneumatic actuator to using an electric motor (or vice versa). This may be useful during alterations to the vehicle 100 -such as refits of equipment and systems within the vehicle 100).

Embodiments of the invention include the clutch mechanism 23. Embodiments of the invention also include a vehicle 100 including a clutch mechanism 23 and/or other components of the automatic door operation unit 2 as described herein. Embodiments of the invention also include methods of fitting a clutch mechanism 23 and/or other components of the automatic door operation unit 2 as described herein to a vehicle 100.

In some embodiments, the input drive element 231 defines the one or more recesses 231e and the output drive element 232 defines the one or more protrusions 232c. In other embodiments, the input drive element 231 defines the one or more protrusions 232c and the output drive element 232 defines the one or more recesses 231e.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

Claims: 1. A clutch mechanism for use with an automatic door operation unit for a vehicle, the clutch mechanism comprising: an input drive element for connection to a drive unit; an output drive element for coupling to a door to drive movement of the door between an open and a closed configuration; and a resilient biasing system to bias the input drive element and the output drive element into engagement such that rotation of the input drive element drives rotation of the output drive element, wherein the engagement is such that: a rotational force greater than a first force in a first direction will cause the input drive element to disengage the output drive element; and a rotational force greater than a second force in a second direction will cause the input drive element to disengage the output drive element, and wherein the first force is less than the second force.
2. A clutch mechanism according to claim 1, wherein the input drive element includes one or more recesses which are configured to be received by one or more protrusions of the output drive element.
3. A clutch mechanism according to claim 1, wherein the output drive element includes one or more recesses which are configured to be received by one or more protrusions of the input drive element.
4. A clutch mechanism according to claim 2 or 3, wherein the or each recess includes a first pair of inclined surfaces.
5. A clutch mechanism according to claim 4, wherein the first pair of inclined surfaces includes a first surface at a first angle with respect to the direction of a biasing force applied by the resilient biasing system and a second surface at a second angle with respect to the direction of the biasing force, the first and second angles being different from each other.
6. A clutch mechanism according to any of claims 2 to 5, wherein the or each protrusion includes a second pair of inclined surfaces.
7. A clutch mechanism according to claim 6, wherein the second pair of inclined surfaces includes a first surface at a first angle with respect to the direction of a biasing force applied by the resilient biasing system and a second surface at a second angle with respect to the direction of the biasing force, the first and second angles being different from each other
8. A clutch mechanism according to any of claims 2 to 7, wherein the or each recess is asymmetric.
9. A clutch mechanism according to any of claims 2 to 8, wherein the or each protrusion is asymmetric.
10. A clutch mechanism according to any preceding claim, wherein the input drive element includes a mounting member for connection to a drive linkage to drive rotation of the input drive element.
11. A clutch mechanism according to any preceding claim, wherein resilient biasing system includes at least one resilient biasing element. 25
12. A clutch mechanism according to any preceding claim, further comprising an inner shaft member, wherein the input drive element is tubular and is configured to receive at least part of the inner shaft member, and the inner shaft member is secured to the output drive element for rotation therewith.
13. A clutch mechanism according to claim 12, wherein the resilient biasing system is configured to act against the inner shaft member and a portion of the input drive element.
14. An automatic door operation unit including: a clutch mechanism according to any preceding claim; a drive linkage coupled to the input drive element of the clutch mechanism; and a drive unit which is configured to drive movement of the drive linkage 10 to cause movement of the input drive element.
15. An automatic door operating unit according to claim 14, further comprising: another clutch mechanism according to any of claims 1 to 13; and another drive linkage coupled to the input drive element of the further clutch mechanism, wherein the drive unit is further configured to drive movement of the other drive linkage to cause movement of the input drive element of the further clutch mechanism.
16. An automatic door operating unit according to claim 15, wherein the drive unit comprises a pinion which is configured to engage a pair of racks, each rack being associated with a respective one of the drive linkages.
17. An automatic door operating unit according to claim 15, wherein the 25 drive unit is configured to be connected to an electric motor or a pneumatic/hydraulic actuator to drive movement of the pinion.
18. A drive unit for use in an automatic door operation unit according to any of claims 14 to 17.
19. A vehicle including a clutch mechanism according to any of claims 1 to 13.
20. A vehicle including an automatic door operation unit according to any of claims 14 to 17.
21. A vehicle including a drive unit according to claim 18.
22. A method of fitting a clutch mechanism to a vehicle including: providing a clutch mechanism according to any of claims 1 to 13; and securing the clutch mechanism to the vehicle.
23. A method of fitting an automatic door operating unit to a vehicle including: providing an automatic door operating unit according to any of claims 14 to 17; and securing the automatic door operating unit to the vehicle.
24. A method of fitting a drive unit to a vehicle including: providing a drive unit according to claim 18; and securing the drive unit to the vehicle.
25. A clutch mechanism substantially as herein described with reference to 25 the accompanying drawings.
26. An automatic door operating unit substantially as herein described with reference to the accompanying drawings.
27. A drive unit substantially as herein described with reference to the accompanying drawings.
28. A vehicle substantially as herein described with reference to the 5 accompanying drawings.
29. A method substantially as herein described with reference to the accompanying drawings.
30. Any novel feature or novel combination of features disclosed herein.