SEAT BELT APPARATUS

The invention relates to seat belt apparatus and particularly to seat belt apparatus for a passenger vehicle seat.

A typical seat belt apparatus for a vehicle includes a belt webbing that runs up from a spool located at a first anchor point on the outboard side of the seat to a D-loop fixed to the vehicle at position that is above shoulder height to typical seat occupants, to define a second anchor point for the webbing. The belt webbing passes through the D-loop to a tongue. The tongue has an aperture through which the webbing is routed. The tongue cooperates with a belt buckle which is fixed to the vehicle via a third anchor point, located on the inboard side of the seat. From the tongue, the webbing passes to a fourth anchor point, on the outboard side of the seat, at which the webbing is fixed to the vehicle. The arrangement is such that when an occupant of the seat pulls the tongue across him/herself and fastens it in the buckle, the portion of the webbing extending from the fourth anchor point to the tongue lies over his/her lap and the portion extending from the tongue to the second anchor point at the D-loop extends across his/her chest.

The way a seat belt webbing lies over the occupant of a passenger vehicle seat is referred to as 'seat belt geometry'. Typically, in the design of a seat belt apparatus for a particular vehicle model, the seat belt geometry is tuned to provide optimised restraint performance for seat occupants ranging in size from 5 ^th percentile female adult to 95 ^th percentile male adult. Restraint performance is usually optimised for performance in frontal impacts, because severe frontal impacts make up over 50% of the serious and fatal injuries sustained in road accidents. This creates a problem, in that a seat belt geometry optimised for frontal impact has the seat belt buckle in a more horizontal orientation, with the buckle pointing toward the front of the vehicle, whereas the optimal seat belt geometry for rollover protection would have the seat belt buckle in a more upright orientation with the top of the buckle pointing more towards the roof of

the vehicle. Tuning the seat belt geometry to perform better for either one of these load cases results in undesirable slack in the seat belt apparatus for the other.

It is known to provide seat belt apparatus with a pre-tensioner device. The purpose of the pre-tensioner device is to take up slack in the seat belt webbing when a collision is detected so as to couple the occupant of the seat to the vehicle earlier than would otherwise be the case. The pre-tensioner device typically comprises a pyrotechnic unit arranged to tension the belt webbing on command from a controller, which would typically be the controller of an airbag system. The pyrotechnic device tensions the belt webbing by either reeling the webbing back into the spool or increasing the path length across the occupant's body by pulling the buckle or second anchor point away from the occupant. The pre-tensioner device merely tensions the belt webbing and does not operate in such a way as to actively control the seat belt geometry. Therefore, the problem of providing optimal seat belt geometry for more than one load case remains, even when a pre-tensioner device is used.

It is an object of the invention to at least in part reduce the effect of this problem and/or provide an alternative to existing seat belt products and methodology.

According to a first aspect of the invention, there is provided a seat belt apparatus for use in a vehicle, comprising a belt having an end region for connection with a first anchor point on the vehicle and a first connector part which is connectable with a second connector part of the apparatus for connection with a second anchor point on the vehicle. In use, when the first and second connector parts are connected a lap portion of the belt is held across the lap region of an occupant of a vehicle seat associated with the seat belt apparatus, and a control device for controlling the orientation of the portion of the belt according to a vehicle event.

In certain vehicle designs, one skilled in the art may employ the function of this system to provide enhanced restraint in the event of a rear or side impact also.

The invention provides the advantage that the seat belt apparatus is responsive to the characteristics of the vehicle event, by adjusting the orientation of the portion of the lap portion of the belt to suit the nature of the vehicle event (e.g. roll over or frontal impact). The seat belt apparatus is therefore optimised to provide the seat occupant with a means of restraint which minimises likely injury.

Preferably, the belt has a second end region for connection with a third anchor point on the vehicle.

The first and second end regions of the belt are preferably anchored on an outboard side of the vehicle seat, when the seat belt apparatus is installed within a vehicle.

Typically, the belt is provided with a guide for connection with a fourth anchor point which is located above the shoulder height of the occupant of the vehicle seat so that, when the first and second connectors are connected to one another, a chest portion of the belt is held across the chest of the occupant. The fourth anchor point is either a part of the vehicle body, chassis, fioorpan or is a point on the seat itself.

In a preferred embodiment, the first end region of the belt is anchored to a spool.

In a further preferred embodiment, the second connector part comprises a buckle and the first connector part comprises a member having a portion, known as a tongue which is releaseably engageable in the buckle.

The control device is preferably operable to cause the lap portion of the belt to move from an orientation selected for restraining the occupant when the vehicle event is a frontal impact to an orientation selected for restraining the occupant when the vehicle event is a vehicle rollover. The belt therefore adopts a position, in normal use, which is most suited to a frontal impact, which is a statistically more common type of vehicle event than a vehicle rollover.

In a preferred embodiment, a first guide member for the belt adopts a relatively forward orientation in normal vehicle use and the control device is operable to move the first guide member to adopt a relatively upright orientation when the vehicle event is a vehicle rollover.

In a first embodiment, the control device comprises an actuating device, such as a pyrotechnic device, which is connected with the first guide member.

The apparatus may also include a second guide member associated with the second connector. The second guide member may be connected with the first guide member by means of a shaft or other connecting part such that the second guide member and the first guide member are on opposite sides of the seat and are caused to rotate together upon actuation of the actuating device. This provides the advantage that, as both 'sides' of the belt are moved together, the balance of forces on the belt is improved. In a preferred embodiment, the actuating device is connected with the shaft via a disc mounted on the shaft.

The apparatus may further comprise a belt pre-tensioning device for pre-tensioning the belt (either the lap portion and/or the chest portion) in response to a vehicle event.

In a second embodiment, the control device includes an actuating device which is operatively connected with a device for pre-tensioning the belt.

For example, the actuating device may comprise a cam or eccentric operatively connected with the pre-tensioning device such that an actuation of the pre-tensioning device that pre-tensions the belt selectively operates the cam to cause the lap portion of the belt to be moved from the orientation selected for restraining the occupant when the vehicle event is a frontal impact (i.e. a relatively forward position) to the orientation selected for restraining the occupant when the vehicle event is a vehicle rollover (i.e. a relatively upright position).

The cam may include an arcuate surface which is engaged by a flexible member of the pre-tensioning device that is connected to the belt, in use. The arrangement of the cam is such that it is caused to rotate by movement of the flexible member when the event is a vehicle rollover and not when the event is a frontal impact.

The arcuate surface of the cam is preferably substantially smooth, whereby movement is transmitted from the flexible member to the cam by friction engagement of the arcuate surface with the flexible member.

In a preferred embodiment, the actuating device is connected with a first guide member which is actuable to rotate the first guide member to move the lap portion of the belt from the orientation selected for restraining the occupant when the vehicle event is a frontal impact to the orientation selected for restraining the occupant when the vehicle event is a vehicle rollover. The first guide member adopts a relatively forward orientation in normal vehicle use, and is actuated by the actuating device to adopt a relatively upright orientation when the vehicle event is a vehicle rollover.

The apparatus may further comprise an additional guide member for the belt connected with the first guide member by means of a shaft, or other connecting part, such that the further guide member and the first guide member are on opposite sides of the seat and are caused to rotate together upon actuation of the actuating device.

In one particular embodiment, the cam is mounted on the shaft so that it has a centre of rotation that is offset with respect to a centre of rotation of the shaft.

According to a second aspect of the invention, there is provided a vehicle seat having a seat belt apparatus as set out in the first aspect of the invention.

According to a third aspect of the invention, there is provided a vehicle comprising a vehicle seat for an occupant and a seat belt apparatus for the seat, the seat belt apparatus

comprising a belt having an end region for connection with a first anchor point on the vehicle and a first connector part which is connectable with a second connector part of the apparatus. The second connector part connects with a second anchor point on the vehicle. In use, when the first and second connector parts are connected, a lap portion of the belt is held across the lap region of an occupant of a vehicle seat associated with the seat belt apparatus. The vehicle further comprises a control device for controlling the orientation of the portion of the belt according to a vehicle event.

According to a fourth aspect of the invention, there is provided a method of controlling orientation of a seat belt of a seat belt apparatus of the first aspect of the invention.

It will be appreciated that preferred and/or optional features of the first aspect of the invention may be incorporated within the vehicle seat of the second aspect of the invention, and/or within the vehicle of the third aspect of the invention and/or may be adapted to provide method features of the fourth aspect of the invention.

For the purpose of this specification, reference to a 'vehicle event' is intended to mean any impact and/or rapid acceleration/deceleration of the vehicle (other than that encountered in normal driving conditions) and/or a violent change in direction of vehicle motion, which results from a physical impact with another vehicle or object and/or which causes the vehicle to tilt or roll, causing vehicle stability to be compromised. Reference to a 'rollover event' shall be taken to mean either the detection of a rollover event or a prediction that a rollover event is about to occur.

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

Figure 1 is a side elevation of a seat showing a seat belt apparatus responding to a frontal impact;

Figure 2 shows the seat belt apparatus of Figure 1 responding to a roll over situation;

Figure 3 is a schematic perspective view illustrating partial features of the seat belt apparatus of Figure 1;

Figure 4 is a partial opposite side elevation of the seat of Figure 1;

Figure 5 is a diagram illustrating operative positions of the seat buckle of the seat belt apparatus of Figure 1;

Figure 6 illustrates an alternative actuating device for use in controlling the seat belt geometry in the seat belt apparatus of Figure 1 showing it in a position corresponding to an optimal seat belt geometry for a frontal impact; and

Figure 7 shows the actuating device of Figure 6 in a position corresponding to an optimal seat belt geometry for a vehicle roll over.

Referring to Figures 1 to 4, a passenger vehicle seat 10 comprises a seat portion 12 and a back support portion 14 that is connected at its lower end to the rear of the seat portion 12. The seat portion 12 is secured to the floor pan 16 of a vehicle in a conventional manner.

The vehicle passenger seat 10 is provided with a seat belt apparatus, referred to generally as 18, for restraining movement of an occupant of the seat in the event the vehicle is involved in a vehicle event such as frontal impact or vehicle rollover. In the drawings, the occupant is represented as mass block 20.

The seat belt apparatus 18 comprises a belt or belt webbing 22, which extends from a spool 24, at a first end thereof, that is fixed to the vehicle at a first anchor point (not shown) located on the outboard side of the seat 10 adjacent to the floor pan 16. The belt

webbing 22 extends upwards from the spool 24 to a D-loop guide 26 that is fitted to the vehicle at a location above shoulder height of a typical occupant of the seat. The D-loop 26 is fitted to the vehicle at a second anchor point of the seat belt apparatus. The D-loop may, in an alternative set-up, be fitted to the seat itself (such an arrangement is often referred to as 'belt-to-seat').

The webbing 22 passes through an aperture in the D-loop 26 to a first connector part in the form of a tongue 28 where it is threaded through an aperture in the tongue 28 to form a third anchor point. The tongue 28 is configured to cooperably engage with a second connector part in the form of a buckle 30 of the apparatus so as to secure the webbing 22 across the lap of the occupant 20. In a known manner, the tongue 28 includes a region that is releaseably engageable in the buckle 30 so as to enable disconnection of the parts 28, 30.

A pre-tensioner means in the form of a pyrotechnic pre-tensioner device 34 is secured to a frame (not identified) of the seat. The pre-tensioner device 34 includes a flexible member in the form of a steel cable 32 which is connected to the buckle 30 and extends, from the buckle 30, around a pivot mount 36, to the pre-tensioner device 34.

Referring also to Figures 2 to 4, the pivot 36 is mounted on a first guard disc 38 that is fixed to a frame -mounted shaft 40 such that it can rotate relative to the seat frame, with the pivot 36 and the first guard disc 38 being coaxial with the shaft 40. Between the buckle 30 and the pivot 36, the steel cable 32 passes through a guide member 42 which keeps the cable close to the seat frame. The guide 42 may be mounted on the first guard disc 38, or it may be a separate member mounted directly on the shaft 40.

The first guard disc 38 is a relatively large diameter disc arranged to prevent foreign objects, such as loose clothing or the feet of rear seat occupants, from impeding the operation of the seat belt apparatus 18.

The shaft 40 extends across the width of the seat portion 12, transversely across the seat, to a belt guide member 44 which is connected with the outboard end of the shaft 40. A further guard disc 45, having the same function as the first guard disc 38, is mounted on the shaft 40 inboard of the belt guide 44. The belt webbing extends over the top of the guard disc 45 to the belt guide 44, which acts to turn the webbing 22 and guide it down the side of the seat portion 12 to a fourth anchor point 29 at the end of the belt webbing 22.

A control means in the form of a second pyrotechnic device 46 is fitted to the outboard side of the seat frame, the pyrotechnic device 46 including a pyrotechnic element housed inside a device housing. A steel cable 48 extends from the second pyrotechnic device 46 and is secured to the shaft 40 such that when the pyrotechnic device 46 is deployed, the steel cable 48 is pulled back into the device housing and the shaft is caused to rotate in a clockwise direction (as viewed from the right in Figure 3). The guides 42, 44 and the second pyrotechnic device 46 thus constitute a control device for controlling the orientation of the seat belt portion 22L of the belt webbing 22 and the buckle 30.

Referring back to Figure 2, the first guard disc 38 is fitted with a first projection 50 that interacts with a stop 52 secured to the seat frame to limit anti clockwise rotation (as viewed in the drawing) of the first guard disc 38 and, thus, anticlockwise rotation of the guides 42, 44. The first guard disc 38 carries a second projection 54 that is positioned to interact with a stop 56 secured to the seat frame to limit clockwise rotation of the guard disc and, thus, clockwise rotation of the guides 42, 44.

Although the illustrated embodiment shows the projections 50 and 54 on the guard discs 38, 45, it will be readily apparent to the man skilled in the art that the same functionality could be achieved by mounting them on the shaft 40.

The apparatus is such that, when the occupant 20 is seated on the seat portion 12 and the tongue 28 is engaged in the buckle 30, a chest portion 22C of the belt webbing 22 extends from the D-loop 26, across the chest of the occupant 20, to the tongue 28. A further, lap portion 22L of the belt webbing 22 extends from the tongue 28 across the lap of the occupant 20 to the belt guide 44 so that in the event of the vehicle being involved in a collision, the occupant is restrained on the seat by the seat belt apparatus 18.

Referring to Figure 5, the buckle 30 is shown in three operative positions. Ideally, for a rollover situation, the buckle would be in a relatively upright position identified as

30(A). For a frontal impact, the buckle would typically have a nominal, relatively forward position 30(B) (i.e. compared with the upright position 30(A)) at which it would be inclined to the vertical by an angle, β, of approximately 15°. However, there is a tolerance on this position and the buckle 30 may be at a fully forward position 30(C), which is forward of the nominal position 30(B) by an angle, α , which would typically be approximately 15°.

In Figure 5, the position 30(B) is the orientation of the buckle in normal use and forms the starting point of the lap belt before the device has been activated. The orientation of the lap belt is optimised for restraint of an occupant in a frontal impact, from which the buckle will be deflected further forward during the restraint of an occupant in a frontal impact to 30(C) due to the loads applied to the lap belt by the restrained occupant. In the case of a rollover event, the buckle and opposing seatbelt guide are raised to a substantially upright position to mitigate vertical excursion of an occupant. It should be noted that any change in orientation from the nominal position, 30(B) towards 30(A) is achieved in conjunction with the pre-tensioning of the seatbelt which is triggered at a pre-determined optimal time offset from the orientation adjustment of the lap belt geometry.

In use, in the event of a frontal impact, the pyrotechnic pre-tensioner device 34 is actuated on receiving a signal from an airbag controller (not shown). The pre-tensioner device 34 functions conventionally to tension the seat belt webbing 22 primarily across the lap of the occupant 20. In this situation, the buckle 30 will be in the nominal position 30(B) or the fully forward position 30(C) of Figure 5. If a rollover event is detected or predicted, the airbag controller sends an additional signal to the second pyrotechnic device 46, causing it to deploy and pull on the steel cable 48. This causes the shaft 40 to rotate in a clockwise direction (as viewed in Figures 1 to 3). The rotation of the shaft causes the guides 42, 44 to rotate clockwise (as viewed in Figures 1 to 3), so moving them from the forward position illustrated by Figure 1 to the more upright position illustrated by Figure 2. In this position the guides 42, 44 are substantially upright so that buckle 30 will be in the substantially upright position 30(A) (as in Figure 5) and the seat belt portion 22L lies in a substantially horizontal plane and is so best positioned to hold the occupant 20 on the seat portion 12 as the vehicle rolls over.

If no rollover event is detected or predicted, no signal is sent to the second pyrotechnic device 46 so that the seat belt portion 22L remains in a position across the lap of the occupant 20 that is best suited to a frontal impact with no rollover (as a frontal impact is statistically much more likely to occur).

Figures 6 and 7 illustrate an alternative actuating device 68 for controlling the orientation of the seat belt portion 22L and the buckle 30 of the vehicle seat belt apparatus 18. In the embodiment shown in Figures 1 to 4, the seat belt apparatus 18 has an additional pyrotechnic device 46, which is used to bring the seat belt portion 22L and the buckle 30 into the desired orientation for a rollover event. The actuating device 68 is intended to avoid the need to provide a second pyrotechnic device (i.e. device 46 in Figures 3 and 4) and so may be preferred in cases where cost and simplicity of design are important considerations.

A seat belt apparatus provided with the actuating device 68 as illustrated by Figures 6 and 7 corresponds generally to the apparatus 18 illustrated by Figures 1 to 4 and, for ease of reference, like or similar parts will be indicated by using the same reference numerals. It should be noted that on the outboard side of the seat 10, the only difference is that there is no second pyrotechnic device 46 and no associated steel cable 48.

Referring to Figures 6 and 7, the first guard disc 38 is secured to the inboard end of the shaft 40 and has its central axis offset from the axis of rotation of the shaft 40. A cam 70 having an arcuate surface is coaxially mounted on the first guard disc 38 such that, when it rotates as a result of tension in the cable 32, that rotation is transmitted to the shaft 40 via the first guard disc 38. The steel cable 32 from the pyrotechnic pre- tensioner device 34 (not shown) extends around the arcuate surface of the cam 70 and connects to the buckle 30 (also not shown). As in the previous embodiment, the steel cable 32 passes through a guide member 42 which keeps the cable close to the seat frame.

The shaft 40 is fitted with a torsion spring (not shown), which is arranged to bias the shaft 40 in an anticlockwise direction (as viewed in Figures 6 and 7) such that the buckle 30 is biased to an optimal position 30(B), 30(C) (as in Figure 5) for a frontal impact. A projection 50 is provided on the first guard disc 38 and an associated stop 52 is fixed relative to the seat frame to limit anticlockwise rotation of the first guard disc 38 by the torsion spring.

The first guard disc 38 is provided with a second projection 54, which is engagable with a stop 56 that is fixed relative to the seat frame. Engagement of the projection 54 with the stop 56 limits clockwise rotation of the first guard disc 38.

As shown in Figures 6 and 7, the steel cable 32 from the pyrotechnic pre-tensioner device 34 engages the periphery of the cam 70. In one scenario, when the pre-tensioner

device 34 is actuated, if the frictional engagement between the steel cable 32 and the cam 70 is insufficient to overcome the resistance to rotation of the first guard disc 38, the steel cable 32 will slip on the substantially smooth surface of the cam 70 and simply act as a conventional pre-tensioner for the belt 22. In another scenario, if the frictional engagement is sufficient, a moment will be applied to the shaft 40 causing it to rotate the first guard disc 38 clockwise from the position illustrated in Figure 6 to the position shown in Figure 7 (the Figure 6 position of the first guard disc 38 and the cam 70 is shown in Figure 7 in dashed lines).

The aforementioned rotation is transmitted to the buckle 30 and to a belt guide 44 via the shaft 40 (as in the previous embodiment). It will be noted that the cam 70 does not simply rotate about its central axis but, instead, it translates laterally to an extent determined by the offset from the axis of rotation of the shaft 40. The translation of the cam 70 causes it to draw the buckle 30 from the forward/nominal positions 30(B), 30(C) to the upright position 30(A). The belt guide 44 is similarly moved to a more upright position so that the seat belt portion 22L is orientated in an optimal position for restraining the occupant during a vehicle rollover.

The skilled person will appreciate that the magnitude of the forces acting on the seat belt apparatus in the event of a frontal impact are typically an order of magnitude greater than in a rollover situation. Accordingly, the friction forces acting on the cam 70, the shaft-to-guide offset and the position of the pivot points can be tuned such that in the case of a frontal impact there is insufficient friction torque to resist the forces exerted on the belt webbing 22 by the occupant 20 and the resistance of the torsion spring. In that case, the steel cable 32 will slide on the cam 70 and the buckle position 30(B), 30(C) will be unaffected, so providing a seat belt geometry that is optimised for a frontal impact. The tuning would be such that in the event of a rollover situation, the torque acting on the cam 70 will be sufficient to overcome the forces exerted by the torsion spring and the seat belt portion 22L so that shaft 40 is rotated to move the

buckle 30 and the seat belt portion 22L to the optimum position for holding the occupant 20 against the seat 10 during vehicle rollover.

When the actuating device 68 is used, the seat belt apparatus 18 preferably further comprises a catch 74 which is pivot mounted to the seat frame. The catch 74 is positioned to engage with the projection 54 so as to prevent clockwise rotation of the guard disc 38/shaft 40 so that the buckle 30 is held in an optimal position 30(B), 30(C) for a frontal impact until the catch 74 is released. The catch 74 can be pivoted by means not shown to move it out of engagement with the projection 54. The catch 74 is moved out of engagement with the projection 54 in response to a signal from an airbag controller (not shown), or a dedicated roll over sensor (not shown) that forms a part of the seat belt apparatus 18.

The reaction time for the pre-tensioner device 34 in the case of a frontal impact may be as little as 20 to 30 milliseconds, whereas in the case of a rollover, it would be an extremely severe event to require activation in under 100 milliseconds. Since the timing requirements are more critical in the case of a frontal impact, it is preferable that the buckle 30, and so the seat belt portion 22L, are biased to the optimal position for a frontal impact. Additionally, if the seat belt apparatus 18 is biased to a position best suited to frontal impact and the steel cable 32 fails to rotate the first guard disc 38, the occupant would not be disadvantaged as compared with occupant of a vehicle fitted with a conventional pre-tensioned seat belt apparatus.

It will be appreciated that by controlling the seat belt geometry, primarily the geometry of the portion of the belt laying across the lap of the occupant, the embodiments improve seat belt performance by reducing forward excursion of the occupant in the event of a frontal impact and vertical movement of the occupant in the case of a roll over event. A further advantage obtained is that the seat belt geometry can be switched to the roll over setting to provide increased restraint of the lower body mass during a severe rear impact, so reducing occupant ramping. One benefit of this is that it would

also improve the performance of a head restraint of the pivoting type that is actuated by a force applied by the occupant's back to a lever extending from a pivot point of the head restraint. It also reduces the possibility of excessive front seat deflection causing injury to rear seat occupants, as loading of the seat frame is reduced when the mass of the occupant's legs is more effectively restrained by the belt.

In the aforementioned embodiments, the buckle 30 is shown on the inboard side of the seat 10 although it is to be understood that this is not essential and the parts of the embodiment could be reversed to suit the configuration of the vehicle. This may be desirable for sports cars or off-road vehicles that often have pronounced intrusion into the occupant compartment by the centre tunnel, which might restrict access to a seat belt buckle mounted inboard. This offers the additional benefit of keeping the front seat occupants apart during the lateral acceleration phase of a rollover as the occupants' torsos cannot 'fall' out of the shoulder belt position.

It is also possible for a pre-tensioning device (such as 34) to be provided on both sides of the seat belt apparatus. For example, the anchor point 29 for the belt webbing 22 (as shown in Figures 3 and 4) may be replaced by an additional pre-tensioner device or retractor.

It is also possible for an alternative type of pre-tensioning device 34 to be used, for example a pre-tensioner that is mounted on a spool. Those skilled in the art will also appreciate that a pre-tensioning device may also be provided to tension the chest portion 22C of the belt webbing 22, in addition to the pre-tensioning device 34 for the lap portion 22L. Both the lap portion 22L and the chest portion 22C of the belt 22 may be provided on a spool.

The skilled man will appreciate that the pyrotechnic device 46 may provide the actuation force to the guard disc 38 on either side of the shaft 40 relative to the buckle 30. Furthermore, it will be apparent to the skilled man that the force from the

pyrotechnic device 46 may be applied to the shaft either by means of a cable wound around it or via a crank feature in the shaft. Moreover, the pyrotechnic device 46 may apply a force to the mechanism either by displacing a piston in a tube via high pressure gas, or by releasing the energy stored in a spring using a latch pin released or displaced by means of a small pyrotechnic charge or squib.

It is also to be understood that the terms 'forwards', 'rearwards', 'clockwise' and 'anticlockwise' have been used for convenience and reference the respective directions in the drawings referred to, and their use, should not be taken as limiting.