Seat latch arrangement

Abstract

A vehicle seat latch arrangement 16 has a latch mechanism 22 that can receive a striker (18, fig 2) in an open position and retain the striker in a locked position, a gear wheel 34 having a projection

Description

TECHNICAL FIELD The present disclosure relates to a seat latch arrangement. Aspects of the invention relate to a seat latch arrangement, a seat assembly, a vehicle body assembly and a vehicle. BACKGROUND It is known to use seat latches to facilitate the secure locking and unlocking of vehicle seats, enabling adjustment and access to different areas of the vehicle. For example, a latch mechanism may be moveable between an open position and a locked position to facilitate the receipt and release a striker to selectively secure and release the vehicle seat to and from part of the vehicle body. An issue with seat latches, particularly powered seat latches, is that the mechanism may become jammed in the open position, which prevents its movement to the locked position. This is primarily due to the misalignment of components as the mechanism moves to the open position. In this way, the vehicle seat may become stuck in an uncomfortable position. In addition, the misaligned components may become worn and damaged, requiring frequent maintenance or replacement, or may cause undesirable noise in operation. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION According to an aspect of the invention, there is provided a seat latch arrangement for releasably retaining a vehicle seat to a vehicle body, the latch arrangement comprising: a latch mechanism moveable between an open position, in which the latch mechanism is operable to receive a striker fixed to one of the vehicle seat and the vehicle body, and a locked position, in which the latch mechanism is operable to retain the striker to retain the vehicle seat to the vehicle body; a gearwheel rotatable about a first axis, the gearwheel comprising a projection configured to abut an engagement feature of the latch mechanism to move the latch mechanism from the locked position to the open position upon rotation of the gear wheel from a first position to a second position; and a drive mechanism configured to drive rotation of the gearwheel in a forward direction to the second position when the drive mechanism is activated, and configured to permit rotation of the gearwheel in a reverse direction when the drive mechanism is deactivated. In this manner, the gearwheel can be moved in the reverse direction away from the second position when the drive mechanism is deactivated to avoid interference between the engagement feature and the projection. For example, the gear wheel may be moved in the reverse direction by the engagement feature as the latch mechanism moves from the open position. This is in contrast to some existing arrangements in which the gear wheel can remain fixed in place by the deactivated drive mechanism, thereby restricting the latch mechanism. The gear wheel may further comprise a biasing means configured to bias the gear wheel in the reverse direction away from the second position. Advantageously, the biasing means moves the gear wheel away from the second position when the drive mechanism is deactivated, thereby preventing the projection from being in a position which interferes with the engagement feature while the latch mechanism is in the open position. As such, the projection does not restrict movement of the engagement feature to move the latch mechanism to the locked position. In this way, the vehicle seat does not get stuck in an uncomfortable or unusable position. In addition, the biasing means facilitates the return of the projection to a consistent position after the drive mechanism is deactivated, allowing for precise and repeatable movement of the gear wheel to abut the projection against the engagement feature for subsequent movement of the latch mechanism to the open position. This consistency allows for an exact understanding of the required number of revolutions and / or time of activation required by the drive mechanism for the gear wheel to rotate to the second position. This is particularly beneficial in automated systems, ensuring reliable repeatable performance. Optionally, the drive mechanism comprises an actuator and a worm screw operatively coupled to the actuator, and wherein the worm screw comprises a helical thread configured to engage and drive the gearwheel in the forward direction and configured to permit rotation of the gearwheel in the reverse direction. Advantageously, the worm screw and actuator facilitate an automated actuation of the latch mechanism to the open position, providing a smooth and quiet rotation of the gearwheel, reducing noise and vibrations while also providing a compact design. Optionally, the gear wheel comprises helical teeth configured to engage with the helical thread of the worm screw such that the gearwheel is operable to drive rotation of the worm screw in the reverse direction. Advantageously, the arrangement of the worm screw and gear wheel provides for a smooth and effective means of rotating the worm screw and gearwheel in both the forward and reverse directions. In this way, the arrangement facilitates the reversal of the gear wheel to move the projection away from the engagement feature and prevent any undesired interference therewith when the latch mechanism is in the open position. This is achieved without the gears becoming disengaged, orwithout any significant wear between components. Optionally, the helical thread of the worm screw defines a helix angle in the range of 20 to 30°. Optionally, the helical teeth of the gearwheel define a helix angle in the range of 20 to 30°. Advantageously, the helix angles of the screw gear and the gear wheel facilitate effective movement of the gears together in the forward and reverse directions, providing smooth engagement between the gears, with increased contact area, allowing the gears to reverse effectively and move the projection away from the engagement feature. Optionally, the drive mechanism comprises a controller for controlling the actuator so as to move the latch mechanism to the open position. Advantageously, the controller provides a precise and accurate means of actuating the latch mechanism, ensuring improved operation of the seat latch arrangement. In other embodiments, a manually activated actuator may be used. Optionally, the controller is configured to activate the actuator to activate the drive mechanism until a predetermined time has elapsed and / or until the controller detects a predetermined torque acting on the gear wheel from the engagement feature. Advantageously, the controller can facilitate the activation of the drive mechanism until the gearwheel is in the second position, by either rotating for a predetermined period of time that has been determined to allow the projection to abut the engagement feature and / or by determining that the projection is abutting the engagement feature as a result of the torque thereon exceeding a predetermined value. The resulting arrangement provides for a consistent and automated means of moving the latch mechanism to the open position. Optionally, the drive mechanism comprises an electrical actuator coupled to the gear wheel, wherein the electrical actuator is configured to be energised when the drive mechanism is activated. Advantageously, the electrical actuator facilitates an effective and automated actuation of the latch mechanism to the open position, providing a more convenient means for a user to move a vehicle seat. Optionally, the biasing means is configured to bias the gearwheel at least 10° about the first axis in the reverse direction away from the second position. Advantageously, the biasing means ensures the projection is sufficiently far removed from the engagement feature to prevent the projection from interfering with the engagement feature when the latch mechanism moves to the locked position. Moreover, the biasing means provides a consistent starting position for the projection, allowing for simpler control to activate the arrangement. Optionally, the biasing means is a torsion spring. Advantageously, a torsion spring has been found to provide a predictable and consistent force, facilitating the consistent locating of the projection when the drive mechanism is deactivated. Optionally, the engagement feature and the projection are shaped and / or positioned such that the engagement feature blocks the projection to prevent rotation of the gearwheel in the forward direction beyond the second position. Advantageously, the gearwheel is prevented from rotating beyond the second position in the forward direction, thus the projection is prevented from rotating beyond the engagement feature and locating in a position which interferes with the engagement feature. Movement of the projection beneath the engagement feature can cause unpleasant noise and / or wear to the components as the projection slides beneath and contacts the engagement feature. The seat latch arrangement prevents the projection from moving forward beneath the engagement feature, therefore resulting in a seat latch arrangement that can smoothly move between the open position and the closed position, without unpleasant noise or significant wear to components. Optionally, the projection extends substantially parallel to the first axis from a face of the gearwheel so as to abut the engagement feature. Advantageously, configuring the projection as an axial projection facilitates the movement of the projection in a consistent path relative to the axis of the gear, providing a consistent force on the engagement feature when the projection abuts it. Moreover, an axial projection is more space efficient compared to a radial projection, and so provide for a more compact latch arrangement. Optionally, the projection defines a radially elongated shape relative to the first axis of the gearwheel. Advantageously, the elongate shape of the projection increases the contact area in the radial direction between the projection and the engagement feature, improving the reliability and effectiveness of the latch arrangement. The elongate shape also provides for increased tolerance to misalignments between the gearwheel and the latch mechanism. The elongate shape also reduces the risk that the projection will rotate beyond the engagement feature in the forward direction. Optionally, the engagement feature is spaced apart from the gearwheel so as to define a gap therebetween, and the projection may be shaped to define a length that is greater than a length of the gap between the gear wheel and the engagement feature. Optionally, the engagement feature is spaced apart from the gear wheel in a direction along the first axis, so as to define a gap therebetween, and wherein the projection is shaped to define a length that is greater than a length of the gap between the gearwheel and the engagement feature. Advantageously, the configuration of the projection prevents it from passing through the gap between the gear wheel and the engagement feature, and thereby prevents the projection from locating so as to interfere with the latch mechanism. Optionally, the projection is positioned relative to the engagement feature such that the projection is blocked by the engagement feature from passing through the gap. Optionally, the engagement feature is axially spaced apart from the gearwheel to define the gap, and wherein the projection is shaped to define an axial length that is greater than an axial length of the gap such that the projection is blocked from passing through the gap. Advantageously, the arrangement of the engagement feature relative to the gearwheel, as well as the shape of the projection, prevents the projection from passing the engagement feature when the gearwheel rotates in the forward direction. In this way, the projection is prevented from interfering with the latch mechanism when in the open position. Optionally, the engagement feature is radially spaced apart from a central region of the gearwheel to define the gap, and wherein the projection is shaped to define a radial length that is greater than a radial length of the gap and / or wherein the projection is positioned relative to the engagement feature such that the projection is blocked from passing through the gap. Advantageously, the projection can be shaped and / or located so as to prevent the projection from passing through the gap, improving the reliability of the latch arrangement and preventing wear between components. Optionally, the projection extends along substantially the entire radial extent of a face of the gearwheel from a region proximate a bore of the gearwheel to a gear teeth region of the gearwheel. Advantageously, the projection extends substantially across a radius defined by the gearwheel. As such, the reliability of the latch arrangement is improved, since the contact area is increased, reducing the risk that the projection does not contact the engagement feature (e.g. compared to the projection occupying a smaller radial extent ofthe gearwheel). The configuration of the projection also reduces the risk that the projection can pass between a radial gap present between the gearwheel and the engagement feature. Optionally, the projection comprises an abutment surface for abutment with the engagement feature. Advantageously, the substantially planar abutment surface provides for more uniform contact between the projection and engagement feature, as well as distributing the load more evenly. This can prevent significant wear to the projection and engagement feature overtime. Optionally, the projection is oriented such that the abutment surface defines a non-zero acute angle relative to a radius ofthe gearwheel. Advantageously, the angled abutment surface can provide a smoother and more effective engagement with the engagement feature, facilitating a controlled and gradual application of force to the engagement feature. In this way, the reliability ofthe latch arrangement is improved, whilst also reducing wear between components due to the more gradual application of force. Optionally, the engagement feature comprises a convex engagement surface for abutment by the projection. Advantageously, the convex engagement surface can provide for a gradual and smoother transition between the locked and the open positions upon abutment ofthe engagement feature by the projection. This reduces wear between moving components, and promotes a smooth transition ofthe car seat between positions. Optionally, the drive mechanism is configured to drive rotation of the gearwheel in a reverse direction when the latch mechanism moves from the open position to the locked position. Optionally, the drive mechanism comprises an electric actuator coupled to the gearwheel. Advantageously, the electric actuator facilitates an automated actuation of the latch mechanism to the open position, providing a more convenient means for a user to move a vehicle seat. According to a further aspect of the invention, there is provided a seat assembly comprising the seat latch arrangement as described herein. Advantageously, the seat assembly benefits from the advantages of the seat latch arrangement outlined above. According to a further aspect of the invention, there is provided a vehicle body assembly comprising a vehicle seat and the seat latch arrangement as described herein. Advantageously, the vehicle body assembly benefits from the advantages of the seat latch arrangement outlined above. According to an aspect of the invention, there is provided a vehicle body assembly comprising a plurality of vehicle seats, wherein each vehicle seat comprises a latch arrangement as described herein. Advantageously, the vehicle body assembly benefits from the advantages of the seat latch arrangement outlined above. According to an aspect of the invention, there is provided a vehicle comprising the vehicle body assembly as described herein. Advantageously, the vehicle benefits from the advantages of the seat latch arrangement outlined above. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of a vehicle in accordance with an embodiment of the invention; Figure 2A shows a schematic of a vehicle body assembly in accordance with an embodiment of the invention; Figure 2B shows a schematic of a vehicle body assembly in accordance with an embodiment of the invention; Figure 3A shows a seat latch arrangement in accordance with the invention, in which a latch mechanism is in a locked position; Figure 3E3 shows the seat latch arrangement of Figure 3A in which the latch mechanism is in the locked position and the gearwheel is in the first position; Figure 3C shows the seat latch arrangement of Figure 3A in which the gear wheel is in the second position and the latch mechanism is in the open position; Figure 3D shows the seat latch arrangement of Figure 3D in which the latch mechanism is in the open position; Figure 4 shows a schematic side view of a portion of the seat latch arrangement of Figure 3A; Figure 5 shows a perspective view of a gearwheel of the seat latch arrangement of Figure 3A; Figure 6 shows a plan view of a front face of a gearwheel and a portion of a drive mechanism of the seat latch arrangement of Figure 3A; Figure 7 shows a perspective rear view of the gear wheel and the latch mechanism of the seat latch arrangement of Figure 3A; Figure 8 shows a worm screw in accordance with an embodiment of the invention; Figure 9 shows the worm screw of Figure 8 engaged the gear wheel of the seat latch arrangement of Figure 3A. DETAILED DESCRIPTION Figure 1 shows a vehicle 10. The vehicle 10 may be a battery electric vehicle (BEV) that is powered by electrical power alone and has no internal combustion engine. The vehicle 10 has an electric machine arranged to provide propulsive torque to the wheels of the vehicle. In some cases, the vehicle 10 may have two or more electric machines, such as a first electric machine to provide torque to the front wheels and a second electric machine to provide torque to the rear wheels. The electric machines may be powered by batteries, which may be arranged between the wheels, e.g. underneath a passenger compartment. In some arrangements, the batteries may locate in a front structure of the vehicle, ortoward a rear of the vehicle (e.g. in the boot ortrunk). The electric machines may be electric motors or motor-generators and may also be referred to as an electric engine. The vehicle 10 has at least one vehicle drive unit. The drive unit may be an electric drive unit. The electric drive unit may contain an electric machine and one or more drivetrain components. The vehicle 10 includes a vehicle body assembly 100. Figures 2A and 2B show a schematic arrangement of a vehicle body assembly 100. The vehicle body assembly 100 includes a vehicle body 12. The vehicle body 12 provides structural support for the vehicle 10. The vehicle body 12 includes for example, a vehicle frame onto which further vehicle components are mounted. The vehicle body 12 includes a plurality of parts permanently coupled together for example using rivets (e.g. self-pierce rivets) or welding, and as such may also be referred to as a body in white 12. The vehicle body assembly 100 includes a vehicle seat 14 for accommodating a driver and / or passenger. The vehicle seat 14 may be a front seat or a rear seat. The vehicle body assembly 100 may include a plurality of vehicle seats. The vehicle body assembly 100 includes a seat latch arrangement 16 schematically illustrated in Figures 2A and 2B. In some arrangements, each vehicle seat 14 may include a respective seat latch arrangement 16. The seat latch arrangement 16 is configured for releasably retaining a vehicle seat 14 to the vehicle body 12. Figure 2A shows a seat 14 retained to the vehicle body 12. The seat latch arrangement 16 retains the seat 14 to the vehicle body 12 to ensure stability during travel. The seat latch arrangement 16 may engage (e.g. hook onto) a striker 18 so as to retain the seat 14 to the vehicle body 12. When the seat latch arrangement 16 is released, the striker 18 is disengaged. Figure 2E3 shows an example arrangement of the seat 14 released from the vehicle body 12. Releasing the seat 14 from the vehicle body 12 allows the seat 14 to pivot for various purposes, such as accessing different areas of the vehicle 10, providing additional loading space or adjusting the seat position for comfort. The seat latch arrangement 16 may be provided on the respective vehicle seat 14, as is shown in Figure 2A and 2B. In this way, a seat assembly 20 may include the seat latch arrangement 16. The seat latch arrangement 16 may be provided fixed to any suitable location of the seat 14, for example on a rear surface or side of the seat 14. In this arrangement, the striker 18 is fixed to the vehicle body 12. The striker 18 may be fixed to an interior surface of the vehicle body 12 that is adjacent the seat latch arrangement 16 on the vehicle seat 14. In alternative arrangements, the seat latch arrangement 16 may be provided on the vehicle body 12. In such an arrangement, the striker 18 may be provided on the vehicle seat 14 such that the seat assembly 20 includes the striker 18. The striker 18 may be provided fixed to any suitable location of the seat 14, for example on the rear or side surface of the seat 14. The seat latch arrangement 16 may be fixed to an interior surface of the vehicle body 12 that is adjacent the striker 18 on the vehicle seat 14. The seat latch arrangement 16 will now be discussed in more detail with reference to Figures 3A to 9. Although not shown, it will be appreciated that the seat latch arrangement 16 may be housed in a casing. The seat latch arrangement 16 includes a latch mechanism 22. The latch mechanism 22 is moveable between a locked position, as shown in Figures 3A and 3B, and an open position, as shown in Figures 3C and 3D. In the open position, the latch mechanism 22 is operable to receive the striker 18 fixed to one of the vehicle seat 14 and the vehicle body 12. In the locked position, the latch mechanism 22 is operable to retain the striker 18 to retain the vehicle seat 14 to the vehicle body 12. The striker 18 is not shown in the figures for purposes of clarity. In some arrangements, the latch mechanism 22 includes a latch hook 24 configured to engage with the striker 18 so as to lock the seat 14 in place. The latch hook 24 may be referred to as a claw in some arrangements. The latch mechanism 22 may include a pawl 28 configured to retain the latch hook 24 in the locked position. The latch hook 24 is pivotable so as to move the latch mechanism 22 between the open position and the locked position. The pawl 28 is pivotably moveable so as to engage and retain the latch hook 24 in the locked position and disengage from and release the latch hook 24 in the open position. The latch hook 24 includes a cavity 26 for receiving and retaining the striker. The cavity 26 may be open when the latch mechanism 22 is in the open position, and closed when the latch mechanism 22 is in the locked position such that the striker 18 is retained in the cavity 26. The latch hook 24 may be configured to pivot to the open position when the pawl 28 disengages from the latch hook 24. The latch hook 24 may be biased toward the open position, e.g. the latch hook 24 may be biased by a spring 24a (see Figure 7). In the figures, the pawl 28 includes a recess 30 configured to receive a protrusion 32 of the latch hook 24 so as to retain the latch hook 24 when in the locked position. The arrangement of the recess 30 and protrusion 32 closes the cavity 26 so as to retain a striker 18 therein. It will be appreciated that the pawl 28 and latch hook 24 may be configured in any suitable way to facilitate the movement of the latch mechanism 22 between respective positions. Alternative arrangements are envisaged in which the latch mechanism 22 includes different components and / or arrangements thereof to facilitate movement between positions. The seat latch arrangement 16 includes a gear wheel 34 pivotable about a first axis A. The gear wheel 34 includes a projection 38 configured to abut an engagement feature 40 of the latch mechanism 22 to move the latch mechanism 22 from the locked position to the open position upon rotation of the gearwheel 34 from a first position to a second position. The seat latch arrangement 16 includes a drive mechanism 36 configured to drive rotation of the gearwheel 34 in a forward direction to the second position. Figure 3A shows the gear wheel 34 prior to being rotated into the first position. Figure 3E3 shows the gear wheel 34 in the first position, in which the projection 38 has rotated in the forward direction to initially abut against the engagement feature. Figure 3C shows the gear wheel 34 in the second position, in which the projection 38 has moved the latch mechanism 22 into the open position. In the context of the figures, the forward direction will be understood to be a clockwise direction. The gear wheel 34 may be any rotatable component that is driveable by a drive mechanism 36, for example, the gear wheel 34 may be a spur gear. The projection 38 is formed on or with the gearwheel 34 such that rotation of the gearwheel 34 about the first axis A changes the circumferential position of the projection 38 about the first axis A. For example, the projection 38 may be fixed to or integrally formed with the gear wheel 34. The engagement feature 40 may be any feature of the latch mechanism 22 that can be abutted by the projection 38 in order to move the latch mechanism from the locked position to the open position. The engagement feature 40 may be located proximal to or adjacent to the gearwheel 34. The projection 38 may be configured, upon abutment with the engagement feature 40, to pivot the pawl 28. This, in turn, pivots the latch hook 24 to release the striker 18, such that the latch mechanism 22 is in the open position. The pawl 28 may be configured to move toward the locked position when the projection 38 is removed from the engagement feature 40. In some arrangements, the pawl 28 is biased toward the locked position, e.g. the pawl 28 may be biased by a spring 28a. In this way, contact between the projection 38 and engagement feature 40 may act against a force provided by a spring to move the pawl 28 toward the open position. In some arrangements, the latch hook 24 and pawl 28 may have complimentary surfaces that abut against each other when the latch mechanism 22 is in the open position such that the latch hook 24 prevents the pawl 28 from pivoting into the locked position. The striker 18 may cause the latch hook 24 to pivot toward the locked position upon contact with a surface of the cavity 26. This pivotal movement may remove contact between the complimentary surfaces of the latch hook 24 and pawl 28 such that the pawl 28 is biased to the locked position. The seat latch arrangement 16 provides for an effective means of moving the latch mechanism 22 between positions, facilitating the simple retaining and releasing of a vehicle seat 14. While the abutment between the projection 38 and the engagement feature 40 provides for a simple transfer of force from the drive mechanism 36 to the latch mechanism 22, issues can arise in some arrangements due to the circumferential location of the projection 38 about the gear wheel 34 when the latch mechanism 22 is in the open position. For example, the projection 38 may locate so as to restrict or block movement of the engagement feature 40 to move the latch mechanism 22 to the locked position. If the gear wheel 34 remains in the second position, as shown in Figure 3C, after the latch mechanism 22 is open, the projection 38 may block or restrict pivotal movement of the latch mechanism 22, e.g. the pawl 28, toward the locked position. In such an event, the vehicle seat 14 may become jammed in the unlocked position, which may be uncomfortable or unusable. For this reason, the drive mechanism 36 is configured to permit rotation of the gearwheel 34 in a reverse direction. In this way, the gearwheel 34 can be rotated in the reverse direction if the engagement feature 40 contacts the projection during movement to the locked position, for example in response to movement of the engagement feature 40, such that the projection 38 is moved away from the engagement feature 40 for example as shown in Figure 3D. This configuration prevents the projection 38 from restricting or blocking movement of the latch mechanism 22 into the locked position and thus prevents the seat latch arrangement 16 from becoming blocked. In the context of the figures, the reverse direction will be understood to be an anticlockwise direction. In alternative arrangements, the respective components may be arranged such that the forward direction is anticlockwise while the reverse direction is clockwise. In some arrangements, the drive mechanism 36 may be configured to drive rotation of the gearwheel 34 in the forward direction to the second position when the drive mechanism 36 is activated, and configured to permit rotation of the gear wheel 34 in the reverse direction when the drive mechanism 36 is deactivated. In some arrangements, the gearwheel 34 may rotate beyond the second position while the latch mechanism 22 is open, resulting in the projection 38 moving beneath or against the engagement feature 40. Movement of the projection 38 beneath or against the engagement feature 40 can restrict movement of the latch mechanism 22 into the locked position, causing the seat latch arrangement 16 to become jammed as discussed above. In addition, an unpleasant noise and wear to components can occur as a result of the projection 38 sliding beneath and / or against the engagement feature 40. Multiple approaches to solve the issue of the seat latch arrangement 16 becoming jammed have been considered and will be discussed in more detail below. Firstly, one or more components of the seat latch arrangement 16 can be configured to prevent rotation of the gearwheel 34 in the forward direction beyond the second position. Put another way, the seat latch arrangement 16 is configured to prevent forward rotation of the gearwheel 34 beyond the second position once the projection 38 has abutted the engagement feature 40 and moved the latch mechanism 22 into the open position. In some arrangements, the engagement feature 40 and the projection 38 are shaped such that the engagement feature 40 blocks the projection 38 to prevent rotation of the gearwheel 34 in the forward direction beyond the second position. Such a configuration prevents the projection 38 moving to an undesired position relative to the engagement feature 40 (e.g. at or beyond the second position or beneath the engagement feature 40), thus preventing the seat latch arrangement 16 from becoming jammed, and reducing unnecessary wear to components as well as unpleasant noise. Figure 4 shows a side view of the gearwheel 34, the projection 38 and engagement feature 40. Other features of the seat latch arrangement 16 have been omitted for purposes of clarity. As can be seen, the engagement feature 40 is spaced apart from the gearwheel 34 so as to define a gap therebetween. The projection 38 may be shaped to define a length that is greater than a length of the gap between the gear wheel 34 and the engagement feature 40 such that the projection 38 is blocked from passing through the gap by the engagement feature 40 as the gearwheel 34 rotates. In some arrangements, the projection 38 may be positioned on the gearwheel 34 relative to the engagement feature 40 such that the projection 38 is blocked by the engagement feature 40 from passing through the gap. The projection 38 may extend substantially parallel to the first axis A from a face 34a of the gearwheel 34 so as to abut the engagement feature 40. In the figure, the engagement feature 40 is spaced apart from the gear wheel 34 in a direction along the first axis A, so as to define an axial gap 42 between the gearwheel 34 and engagement feature 40 along the first axis A. The projection 38 is shaped to define an axial length Li that is greater than an axial length L2 of the gap 42. This prevents the projection 38 from passing through the axial gap 42 so as to slide beneath the engagement feature 40 beyond the second position. The engagement feature 40 may be radially spaced apart from the first axis A of the gearwheel 34. The projection 38 may be shaped or radially positioned relative to the engagement feature 40 so as to be blocked by the engagement feature 40 as the gearwheel 34 rotates. As can be best seen in Figures 5 and 6, the projection 38 may define an elongated shape. In some arrangements, the projection 38 may define a paddle shape. The projection 38 defines a radially elongated shape relative to the first axis A of the gear wheel 34. It will be understood that the term “radially elongated shape” refers to a length of the projection 38 in a radial direction relative to the first axis A being greater than a length in other directions (e.g. axial, circumferential). The elongated shape of the projection 38 increases the contact area in the radial direction between the projection 38 and the engagement feature 40, improving the reliability of the latch arrangement 16 allowing for increased tolerance to misalignments while reducing the likelihood that the projection 38 will slide beneath the engagement feature 40. The projection 38 may extend along substantially the entire radial extent of the face 34a of the gearwheel 34. The projection 38 may extend from a region proximate a bore 34b of the gearwheel 34 to a gear teeth region 34c of the gearwheel 34, as shown in the figures. Such a radial extension of the projection 38 improves the reliability of the seat latch arrangement 16 by increasing the area of the projection 38 available for contact with the engagement feature 40. This reduces the risk that the projection 38 does not contact the engagement feature 40, whilst also reducing the risk that the projection 38 can pass through any gap between the gear wheel 34 and the engagement feature 40. The projection 38 may include a planar abutment surface 38a for abutment with the engagement feature 40. The planar abutment surface 38a may provide for more uniform contact between the projection 38 and the engagement feature 40, facilitating an even distribution of load that prevents significant wear between components. As can be seen in the figures, the planar abutment surface 38a extends along a radius of the face 34a of the gearwheel 34. Put another way, the planar abutment surface 38a is substantially parallel to the radius of the face 34a of the gearwheel 34 in plan view. In alternative arrangements, the abutment surface 38a may define a non-zero acute angle relative to the radius of the gearwheel. It will be understood that the radius of the face 34a of the gearwheel 34 is defined between the bore 34b (e.g. inner edge) and gear teeth region 34c (e.g. outer edge) of the face 34a of the gearwheel 34. In some arrangements, the projection 38 is oriented such that the abutment surface 38a defines said non-zero acute angle relative to the radius of the gearwheel 34 (e.g. the projection 38 itself may be offset from the radius). The abutment surface 38a may be angled so as to extend in a direction away from the engagement surface 40 as the gear wheel 34 rotates in the forward direction toward the second position. Angling the abutment surface 38a provides a smoother and more gradual application offeree from the projection 38 to the engagement feature 40, improving the reliability of the latch arrangement 16. Returning to Figures 3A to 3D, the engagement feature 40 may include a convex engagement surface 40a for abutment by the projection 38. The convex engagement surface 40a may provide for a gradual and smoother transition of the latch mechanism 22 between the locked and open positions upon abutment of the engagement feature 40 by the projection 38. The engagement feature 40 may define a generally bulbous shape so as to define the convex engagement surface 40a. The respective surfaces 38a, 40a of the projection 38 and the engagement feature 40 may be complimentary to one another so as to facilitate effective abutment therebetween. In some arrangements, the engagement feature 40 may be a part of or fixed to the pawl 28. The engagement feature 40 may be an arm of the pawl 28. In some arrangements, the pawl 28 may locate between the gear wheel 34 and the latch hook 24. The engagement feature 40 of the pawl 28 may be positioned at or proximal a first distal end of the pawl 28, while the recess 30 for receiving the latch hook 24 may be located at or proximal to a second distal end of the pawl 28 that is opposite to the first distal end. The engagement feature 40 and the recess 30 may locate at or toward opposing ends of the pawl 28. It will be appreciated that the engagement feature 40 may be a separate component from the pawl 28 in alternative arrangements, that is operatively coupled to one or more components of the latch mechanism 22. Although not shown, the gearwheel 34 may include a stop to restrict rotation of the gearwheel 34 beyond the second position. The stop may be in the form of a pin, block or tab that prevents rotation of the gearwheel 34 beyond a predetermined position. The stop can be seen as a backup mechanism to prevent the projection 38 from interfering with the engagement feature 40 beyond the second position, further reducing the likelihood that the latch arrangement 16 will become blocked. As has been discussed, configuring the engagement feature and the projection such that the engagement feature blocks the projection to prevent rotation of the gearwheel in the forward direction beyond the second position is advantageous in preventing the seat latch arrangement 16 from becoming jammed. An alternative or complimentary approach to solving the issue of the seat latch arrangement 16 becoming blocked as a result of the position of the projection 38 will now be discussed. The gearwheel 34 may include a biasing means 44 (see Figure 7) configured to bias the gearwheel 34 in the reverse direction away from the second position. The biasing means 44 is configured to move the gearwheel 34 away from the second position when the drive mechanism 36 is deactivated, thereby preventing the projection 38 from interfering with the engagement feature 40 when the latch mechanism 22 is open. As such, the projection 38 does not restrict movement of the engagement feature 40 when the latch mechanism 22 moves to the locked position, preventing the vehicle seat 14 from being jammed in an unusable position. The biasing means 44 may be configured to rotate the gear wheel 34 by a predetermined extent, so as to return the projection to a substantially consistent position on the gear face 34a when the drive mechanism 36 is deactivated, for example the position shown in Figure 3D. This allows for more precise and repeatable movement of the gearwheel 34 into the second position, which is particularly beneficial in automated systems, ensuring reliable repeatable performance. It will be understood that the biasing means is configured to bias the gearwheel 34 by an angle relative to the first axis A large enough to move the projection 38 away from the engagement feature 40. In some arrangements, the biasing means 44 is configured to bias the gearwheel 34 at least 10°, optionally at least 20°, optionally at least 30° about the first axis A in the reverse direction away from the second position. In the illustrated arrangement, the gearwheel 34 is rotated approximately 90° about the first axis A in the reverse direction away from the second position (e.g. between Figure 3C and Figure 3D). The biasing means 44 may be a spring in some arrangements. The biasing means 44 may be any suitable spring, for example a torsion spring or a compression spring. Figure 7 shows a rear of the gearwheel 34. In this arrangement, the biasing means is provided as a torsion spring provided in the bore 34b of the gearwheel 34. The biasing means 44 may provide an alternative or additional means of preventing the projection 38 from locating in an undesirable position. For example, in arrangements in which the biasing means 44 is present, it may not be necessary for the projection 38 and engagement feature 40 to be shaped such that the engagement feature 40 blocks the projection 38. In such an arrangement, the projection 38 may not be shaped as shown in the figures so as to be restricted from passing beyond the engagement feature 40. For example, the projection 38 may have a smaller axial or radial extent and is thus not blocked by the engagement feature 40. Similarly, the biasing means 44 may not be necessary in arrangements in which the projection 38 and engagement feature 40 are shaped such that the engagement feature 40 blocks the projection 38 as the gear wheel 34 rotates. In some arrangements, the gear wheel 34 includes the biasing means 44 and the projection 38 and engagement feature 40 are shaped such that the engagement feature 40 blocks the projection 38. This arrangement serves to both restrict movement of the projection 38 beyond the engagement feature 40 in the forward direction, and bias the gearwheel 34 such that the projection 38 is moved away from the engagement feature 34 when the drive mechanism 36 is deactivated. The combination of these features greatly reduces the risk that the projection 38 will locate in an undesirable position relative to the engagement feature 40, whilst also providing for improved control over the movement of the latch mechanism 22 into the open position and reducing unpleasant noise and wear to components. The drive mechanism 36 will now be discussed in more detail with reference to Figures 3A to 3D alongside Figures 8 and 9. Any and all features of the drive mechanism 36 discussed herein may be applicable to the arrangement in which the biasing means 44 is present, to the arrangement in which the projection 38 and engagement feature 40 to be shaped such that the engagement feature 40 blocks the projection 38, and to arrangements in which both features are present. The drive mechanism 36 may be activated be a user input. For example, the drive mechanism 36 may be manually activated by a user pressing a button or pulling a handle. In other arrangements, the drive mechanism 36 may be electrically activated based on an input of a user, e.g. pressing a button on a console of the vehicle 10 to send an electrical signal to the drive mechanism 36. As will be discussed in more detail below, the drive mechanism 36 may become deactivated after a predetermined time has elapsed or after a detection that the latch mechanism 22 has moved to the open position. The drive mechanism 36 may include an actuator 46 operatively coupled to the gear wheel 34. The actuator 46 may be an electrical actuator. The electrical actuator may be energised when the drive mechanism 36 is activated and may be de-energised when the drive mechanism 36 is deactivated. The electrical actuator may be powered by any suitable means in the vehicle, for example by one or more electrical machines of the vehicle 10. It will be appreciated that the actuator 46 may be any suitable form to induce a rotational movement in the gearwheel 34, for example the actuator 46 may be hydraulic, pneumatic, mechanical or the like. The actuator 46 may be an electric motor in some arrangements. The drive mechanism 36 may include a controller 52, which is indicated schematically in the figures. The controller 52 may be configured to control the actuator 46 so as to move the latch mechanism 22 to the open position. The controller 52 may convey a signal to the actuator 46 to rotate the gearwheel 34 into the second position upon receiving a signal based on a user input. For example, a user may press a button or switch (e.g. on a console) when it is desired to disconnect the vehicle seat 14 from the vehicle body 12, which sends an electrical signal to the controller 52. The controller 52 may then activate the actuator 46, e.g. by energising the actuator 46, so as to active the drive mechanism 36. The controller 52 may be configured to activate or energise the actuator 46 to activate the drive mechanism 36 until a predetermined time has elapsed. For example, it may be determined that the gear wheel 34 will rotate into the second position and move the latch mechanism 22 into the open position after being driven by the drive mechanism 36 fora predetermined amount of time, after which the actuator 46 can be de-energised. In alternative arrangements, the controller 52 may be configured to activate or energise the actuator 46 to activate the drive mechanism 36 until the gear wheel 34 has rotated a predetermined distance. In such an arrangement, the controller 52 may be connected to a position sensor that detects the circumferential position of the projection 38 relative to the first axis A. In some arrangements, the controller 52 may be configured to activate or energise the actuator 46 to activate the drive mechanism until the controller detects a predetermined torque acting on the gearwheel 34 from the engagement feature 40. In such an arrangement, the controller 52 may be connected to a torque sensor, for example a strain gauge sensor, that provides signals to the controller 52 based on the torque between the gearwheel 34 and the engagement feature 40. In some arrangements, the drive mechanism 36 may be configured to drive rotation of the gearwheel 34 in the reverse direction when the latch mechanism 22 moves from the open position to the locked position. For example, the drive mechanism 36 may be configured to detect movement of the latch mechanism 22 toward the locked position and / or detect contact between the engagement feature 40 and the projection 38 as the latch mechanism 22 moves toward the locked position and in response thereto energise the actuator 46 to induce a reverse movement in the gearwheel 34. In some arrangements, the actuator 46 may directly drive rotation in the gear wheel 34. The gear wheel 34 may be mounted on a shaft (not shown) that is rotated by the actuator 46 so as to move the gear wheel 34 towards and away from the second position. In alternative arrangements, the actuator 46 may indirectly drive rotation in the gearwheel 34. The drive mechanism 36 may include a worm screw 48. The worm screw 48 may be operatively coupled to the actuator 46. The worm screw 48 may be operatively coupled to the gear wheel 34 so as to transfer motive force between the actuator 46 and the gear wheel 34. In such an arrangement, the gear wheel 34 may be referred to as a worm gear. As can be seen in Figure 3A and 3E3, the drive mechanism 36 may include a spindle 50 upon which the worm screw 48 is mounted. The actuator 46 may drive rotation of the spindle 50 so as to rotate the worm screw 48 in a forward direction. The worm screw 48 may be configured to facilitate the reverse movement of the gearwheel 34, forexamplewhen the engagement feature 40 contacts the projection 38 as the latch mechanism 22 moves toward the locked position. In arrangements in which the biasing means 44 is present, the biasing means 44 may be configured to overcome forces between the gear wheel 34 and the worm screw 48 so as to back drive the actuator 46 in the reverse direction when the actuator is deenergised. As can be best seen in Figure 8, the worm screw 48 may include a helical thread 48a configured to engage and drive the gearwheel 34 in the forward direction and configured to permit rotation of the gearwheel 34 in the reverse direction. In arrangements in which the actuator 46 is electrical, the helical thread 48a of the worm screw 48 may be configured to drive the gear wheel 34 in the forward direction when the electric actuator 46 is energised and configured to permit rotation of the gearwheel in a reverse direction when the electric actuator 46 is de-energised. In this way, any contact between the engagement feature 40 and the projection 38 as the latch mechanism 22 moves toward the locked position will not cause the latch mechanism 22 to be blocked. Instead, the worm screw 48 is configured such that contact between the engagement feature 40 and the projection 38 causes the gearwheel 34 to move with the worm screw 48 in a reverse direction. The gearwheel 34 may include helical teeth 34d configured to engage with the helical thread 48a of the worm screw 48 such that the gear wheel 34 can drive rotation of the worm screw 48 in the reverse direction. The helical teeth 34d of the gearwheel 34 may be configured to be complimentary to the helical thread 48a of the screw 48. The arrangement of the helical thread 48a and helical teeth 34d provides for a smooth and effective means of rotating the worm screw 48 and gear wheel 34 in both the forward and the reverse directions. The complimentary thread and teeth maintains engagement between the gear wheel 34 and worm screw 48 irrespective of the direction of rotation. In this way, the gearwheel 34 can move in the reverse direction when contacted by the engagement member 40 as the latch mechanism 22 locks and / or when biased by the biasing means 44 (if present) when the drive mechanism 36 is deactivated. The helical thread 48a of the worm screw 48 defines a helix angle that is the same as a helix angle of the helical teeth 34d of the gear wheel 34. The helical thread 48a of the worm screw 48 may define a helix angle in the range of 20 to 30°, optionally between 23 to 26°, optionally around 24°. The helical teeth 34d of the gear wheel 34 may define a helix angle in the range of 20 to 30°, optionally between 23 to 26°, optionally around 24°. These angles have been found to maintain engagement between the gears irrespective of direction of rotation, allowing the gearwheel 34 to move in the reverse direction upon contact between the engagement feature 40 and the projection 38 as the latch mechanism 22 moves to the locked position. In addition, the configuration of the gear 34 and worm screw 48 supports the movement of the gear 34 in the reverse direction in response to the biasing means 44. It will be understood that the helix angle of the gear teeth 34d is defined between a centreline of the respective tooth and the first axis of the gear wheel 34. The helix angle of the helical thread 48a is defined between a centreline of the respective thread and the rotational axis of the worm screw 48, for example the axis defined by the spindle 50. An example means of operating the seat latch arrangement 16 will now be discussed. Initially, the latch mechanism 22 may be in the locked configuration and retaining a striker 18 so as to lock the vehicle seat 14 to the vehicle body 12 as shown in Figure 2A. The seat latch arrangement 16 may be as shown in Figure 3A. When it is desired to disconnect the seat 14 from the vehicle body 12, for example to move the position of the seat 14, a user may activate the drive mechanism 36, for example by pressing a button on a console of the vehicle 10. Activation of the drive mechanism 36 will energise the actuator 46 so as to rotate the worm screw 48 and gearwheel 34 in the forward direction. The gearwheel 34 will rotate into the first position, in which the projection 38 has moved into abutment with the engagement feature 40, as shown in Figure 3E3. The gear wheel 34 will continue to rotate in the forward direction to locate in the second position, in which the projection 38 has pushed the engagement feature 40 to pivot the latch mechanism 22 into the open position, as shown in Figure 3C. When the latch mechanism 22 is in the open position, the striker may be released and the seat 14 may be moveable relative to the vehicle body 12, e.g. as shown in Figure 2E3. The drive mechanism 36 may be configured to deactivate once the latch mechanism 22 is in the open position, for example, the actuator 46 may be de-energised after a predetermined time has elapsed, so that the gear wheel 34 no longer rotates in the forward direction. The shape of the projection 38 and engagement feature 40 may prevent the gearwheel 34 from rotating beyond the second position prior to the drive mechanism 36 being deactivated, thus preventing unpleasant noise and wear as the projection 38 passes the engagement feature 40. In arrangements in which the biasing means 44 is present, the biasing means 44 acts to rotate the gear in the reverse direction away from the second position once the actuator 46 is de-energised, for example as shown in Figure 3D. The configuration of the drive mechanism 36, for example the helical thread 48a of the worm gear 48 and the helical teeth 34d of the gearwheel 34, facilitates the movement ofthe gearwheel 34 in the reverse direction in response to the biasing means 44. When it is desired to lock the vehicle seat 14 to the vehicle body 12, the striker 18 may be pushed into the latch mechanism 22 so as to move the mechanism 22 to the locked position. In arrangements in which the biasing means 44 is not present, the gearwheel 34 may still locate in the second position as shown in Figure 3C. The configuration ofthe drive mechanism 36 facilitates the movement ofthe gearwheel 34 in the reverse direction as the engagement feature 40 moves against the projection 38 into the locked position. Alternatively, when the biasing means 44 is present, the projection 38 has already moved away from the engagement feature 40. 5 It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. It should also be noted that whilst the appended claims set out particular combinations of features described above, the scope of the present disclosure is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features herein disclosed. 10

Claims

1. A seat latch arrangement for releasably retaining a vehicle seat to a vehicle body, the latch arrangement comprising:a latch mechanism moveable between an open position, in which the latch mechanism is operable to receive a striker fixed to one of the vehicle seat and the vehicle body, and a locked position, in which the latch mechanism is operable to retain the striker to retain the vehicle seat to the vehicle body;a gearwheel rotatable about a first axis, the gearwheel comprising a projection configured to abut an engagement feature of the latch mechanism to move the latch mechanism from the locked position to the open position upon rotation of the gearwheel from a first position to a second position; anda drive mechanism configured to drive rotation of the gearwheel in a forward direction to the second position when the drive mechanism is activated, and configured to permit rotation ofthe gearwheel in a reverse direction when the drive mechanism is deactivated;wherein the gear wheel further comprises a biasing means configured to bias the gear wheel in the reverse direction away from the second position.

2. The seat latch arrangement according to claim 1, wherein the drive mechanism comprises an actuator and a worm screw operatively coupled to the actuator, and wherein the worm screw comprises a helical thread configured to engage and drive the gearwheel in the forward direction and configured to permit rotation ofthe gearwheel in the reverse direction.

3. The seat latch arrangement according to claim 2, wherein the gearwheel comprises helical teeth configured to engage with the helical thread ofthe worm screw such that the gearwheel is operable to drive rotation of the worm screw in the reverse direction.

4. The seat latch arrangement according to claim 3, wherein the helical thread of the worm screw defines a helix angle in the range of 20 to 30° and wherein the helical teeth ofthe gearwheel define a helix angle in the range of 20 to 30°.

5. The seat latch arrangement according to any of claims 2 to 4, wherein the drive mechanism comprises a controller for controlling the actuator so as to move the latch mechanism to the open position.

6. The seat latch arrangement according to claim 5, wherein the controller is configured to activate the actuator to activate the drive mechanism until a predetermined time has elapsed and / or until the controller detects a predetermined torque acting on the gearwheel from the engagement feature.

7. The seat latch arrangement according to preceding claim, wherein the drive mechanism comprises an electrical actuator coupled to the gear wheel, wherein the electrical actuator is configured to be energised when the drive mechanism is activated.

8. The seat latch arrangement according to any preceding claim, wherein the biasing means is configured to bias the gearwheel at least 5° about the first axis in the reverse direction away from the second position.

9. The seat latch arrangement according to any preceding claim, wherein the biasing means is a torsion spring.

10. The seat latch arrangement according to any preceding claim, wherein the engagement feature and the projection are shaped and / or positioned such that the engagement feature blocks the projection to prevent rotation of the gearwheel in the forward direction beyond the second position.

11. The seat latch arrangement according to any preceding claim, wherein the projection extends substantially parallel to the first axis from a face of the gearwheel and defines a radially elongated shape relative to the first axis of the gearwheel.

12. The seat latch arrangement according to any preceding claim, wherein the projection comprises an abutment surface for abutment with the engagement feature, and wherein the projection is oriented such that the abutment surface defines a non-zero acute angle relative to a radius of the gearwheel.

13. A seat assembly comprising the seat latch arrangement of any preceding claim.

14. A vehicle body assembly comprising a vehicle seat and the seat latch arrangement of any of claims 1 to 12.

15. A vehicle comprising the vehicle body assembly of claim 14.s

Images