Adjustable headrest assembly

Abstract

An adjustable headrest assembly 100 for an automobile seat (30, Fig. 3) comprising: a headrest 36; a support post arrangement 102; a slider arrangement 104 coupling the headrest to the support post ar

Description

TECHNICAL FIELD The present disclosure relates to an adjustable headrest assembly. Aspects of the invention relate to an adjustable headrest assembly, to an automobile seat assembly, and to a vehicle. BACKGROUND Automobile vehicles, such as passenger vehicles, have automobile seats in which a driver or passenger can sit whilst inside the vehicle. Typically, at least the driver’s seat is adjustable in order to suit different body sizes, shapes and user preferences. For example, the seat may be slid forwards or backwards to move the driver closerto the pedals / steering wheel of the vehicle and / orto adjust passenger legroom within the vehicle. A seat back of the seat may also be pivoted forwards or backwards relative to a base of the seat, to suit a particular driver / passenger preferences. A headrest of the seat may also be adjusted (e.g., to change a height or position of the headrest). A shape of the seat may also be adjusted (e.g., to change the shape of a lumbar support area of the seat back). In some vehicles, one or more electric motors are provided to assist with adjustment of the automobile seat. 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 Aspects and embodiments of the invention provide an adjustable headrest assembly, an automobile seat assembly, and a vehicle.as claimed in the appended claims. According to an aspect of the present disclosure, there is provided an adjustable headrest assembly for an automobile seat. The adjustable headrest assembly comprises: a headrest; a support post arrangement for securing the headrest to an automobile seat; and a slider arrangement coupling the headrest to the support post arrangement. The slider arrangement comprises a guide fixed relative to the support post arrangement and a slider fixed relative to the headrest. The slider is slidably connected to the guide to translate along a slide path. The adjustable headrest assembly also comprises a fluid actuator configured to drive movement of the slider along the slide path in order to translate the headrest relative the support post arrangement. It will be understood that when the support post arrangement is secured to an automobile seat in use, the fluid actuator is configured to drive movement of the slider along the slide path in order to translate the headrest relative to the automobile seat (e.g., relative to a seat back of the automobile seat). This allows the headrest position to be adjusted to suit the driver sat in the automobile seat. Such an adjustable headrest assembly having a slider arrangement and a fluid actuator may provide a simpler and / ormore compact and / or lower carbon dioxide equivalent arrangement than alternative configurations (e.g., in which an electric motor is used to reposition a headrest). In addition, in configurations where a source of fluid is already available (e.g., a pneumatic pump for driving pneumatic massage cells), the use of a fluid actuator may reduce the component count of the adjustment system, which provides a more efficient arrangement. It will be understood that the slider may be configured to slide along the slide path in two opposite directions (e.g., forwards and backwards). Optionally, the slide path is transverse to the support post arrangement. For example, the fluid actuator may be configured to drive movement of the slider along the slide path in order to translate the headrest transversely relative to the support post arrangement. As the support post arrangement is typically received within the seat back (e.g., approximately parallel to a central axis of the seat back), then such a fluid actuator is configured to drive movement of the slider along the slide path in order to translate the headrest in a direction which is substantially perpendicular to the central axis of the seat back. In other words, the slide path may be substantially perpendicular to the central axis of the seat back in use. When the seat back is oriented within a vehicle so that the central axis of the seat back is approximately vertical, this corresponds to the fluid actuator driving movement of the slider along the slide path in order to translate the headrest forwards and backwards within the vehicle. It will be understood that the phrase “substantially perpendicular to the central axis of the seat back” used herein may refer to a direction that is within 30 degrees of perpendicular to the central axis of the seat back, within 25 degrees, within 20 degrees, or with 15 degrees of perpendicular to the central axis of the seat back. Where the seat back comprises multiple portions along its height which are set at an angle to each other, such as in an articulated seat back comprising two or more parts connected by one or more hinges, the term “central axis” may refer to the central axis of the upper part, or to the central axis of the complete seat back. Optionally, the fluid actuator comprises at least one flexible bladder configured to receive pressurised fluid to enlarge the at least one flexible bladder in order to push the slider along the slide path. Such a flexible bladder may provide a simple, lightweight, compact and quiet actuator in comparison to alternative types of actuator. Optionally, the or each flexible bladder comprises a concertinaed bladder, an elasticated bladder, or any other suitable type of flexible bladder. Optionally, the at least one flexible bladder has a primary expansion direction which is generally aligned with the slide path. In other words, the at least one flexible bladder is configured to expand primarily in a direction which is generally aligned with the slide path. Put another way, the flexible bladder is configured to expand more in a direction which is generally aligned with the slide path than in directions which are transverse to the slide path. In this way, a greater movement of the headrest relative to the support post arrangement can be achieved for a given volume of pressurised fluid input to the flexible bladder than in alternative configurations where the flexible bladder expands equally in all directions as it is enlarged (e.g., inflated). For example, the flexible bladder may have first and second ends which are substantially perpendicular to the slide path, and one or more sides (e.g., concertinaed or elasticated sides) extending substantially parallel to the slide path and connecting the first and second ends. In this way, the first and second ends may be pushed apart from each other in a direction parallel to the slide path as the flexible bladder is enlarged by pressurised fluid (e.g., by stretching the one or more sides in the direction parallel to the slide path). In such a configuration, the one or more sides may be inhibited from bulging outwards in directions transverse to the slide path. The first and second ends may define abutment surfaces for engaging corresponding reaction surfaces fixed relative to the support post arrangement and headrest, in order to drive movement of the slider along the slide path as the flexible bladder is enlarged. Optionally, the at least one flexible bladder is configured so that, as the flexible bladder is enlarged in use, expansion of the flexible bladder in directions transverse to the primary expansion direction is less than 20%, optionally less than 10%, optionally less than 5%, of the expansion in the primary expansion direction. In this way, a greater movement of the headrest relative to the support post arrangement can be achieved for a given volume of pressurised fluid input to the flexible bladder than in alternative configurations where the flexible bladder expands equally in all directions as it is enlarged (e.g., inflated). Optionally, the adjustable headrest assembly comprises a first reaction surface which is fixed relative to the support post arrangement, and a second reaction surface which is fixed relative to the headrest and which faces the first reaction surface, wherein the fluid actuator is configured to move the first and second reaction surfaces away from each other to adjust a spacing distance between the first and second reaction surfaces, and thereby drive movement of the slider along the slide path in a first sliding direction. Such reaction surfaces provide suitable surfaces which can be pushed apart / pulled together in order to drive movement of the slider along the slide path. Optionally, the at least one flexible bladder comprises a flexible bladder which is positioned between the first and second reaction surfaces. Optionally, the flexible bladder is configured to receive pressurised fluid to enlarge the bladder in order to act on the first and second reaction surfaces to increase a spacing distance between the first and second reaction surfaces, and thereby drive movement of the slider along the slide path in a first sliding direction. By positioning the flexible bladder between the first and second reaction surfaces, control of the relative positions of the first and second reaction surfaces (and thus the headrest and support post arrangement coupled thereto) can be achieved by adjusting the amount of enlargement (e.g., inflation) of the flexible bladder. Optionally, the first and second reaction surfaces are positioned so that a separation distance between the headrest and the support post arrangement is increased as the spacing distance between the first and second reaction surfaces is increased. Alternatively, the first and second reaction surfaces may be positioned so that a separation distance between the headrest and the support post arrangement is decreased as the spacing distance between the first and second reaction surfaces is increased. Optionally, the adjustable headrest assembly comprises a third reaction surface which is fixed relative to the support post arrangement, and a fourth reaction surface which is fixed relative to the headrest and which faces the third reaction surface, wherein the fluid actuator is configured to move the third and fourth reaction surfaces away from each other to adjust a spacing distance between the third and fourth reaction surfaces, and thereby drive movement of the slider along the slide path in a second sliding direction. Such reaction surfaces provide suitable surfaces which can be pushed apart / pulled together in order to drive movement of the slider along the slide path. Such a configuration also provides simple two-way directional control of the headrest relative to the support post arrangement. Optionally, the at least one flexible bladder comprises a further flexible bladder positioned between the third and fourth reaction surfaces. Optionally, the further flexible bladder is configured to receive pressurised fluid to enlarge the bladder in order to act on the third and fourth reaction surfaces to increase a spacing distance between the third and fourth reaction surfaces, and thereby drive movement of the slider along the slide path in a second sliding direction opposite to the first sliding direction. By positioning the further flexible bladder between the third and fourth reaction surfaces, control of the relative positions of the third and fourth reaction surfaces (and thus the headrest and support post arrangement coupled thereto) can be achieved by adjusting the amount of enlargement (e.g., inflation) of the further flexible bladder. It will be understood that the flexible bladder between the first and second reaction surfaces may receive pressurised fluid to increase the internal volume thereof at the same time as pressurised fluid being expelled from the further flexible bladder between the third and fourth reaction surfaces to reduce the internal volume thereof, and vice versa. In this way, two-way control of the position of the headrest relative to the support post arrangement can be achieved by adjusting which flexible bladder the pressurised fluid is delivered to. Optionally, the third and fourth reaction surfaces are positioned so that a separation distance between the headrest and the support post arrangement is decreased as the spacing distance between the third and fourth reaction surfaces is increased. Alternatively, the third and fourth reaction surfaces may be positioned so that a separation distance between the headrest and the support post arrangement is increased as the spacing distance between the third and fourth reaction surfaces is increased. It will be understood that, where the first and second sliding directions are opposite directions along the slide path, the first to fourth reaction surfaces will be positioned so that the spacing distance between the first and second reaction surfaces increases as the spacing distance between the third and fourth reaction surfaces decreases, and vice versa. In some embodiments, a spring or other resilient element is provided between the third and fourth reaction surfaces (e.g., compressed spring for urging the third and fourth reaction surfaces apart). Such a spring or other resilient element may be provided instead of or as well as a further flexible bladder provided between the third and fourth reaction surfaces, e.g., as an alternative means of driving movement of the slider along the slide path. Optionally, the adjustable headrest assembly comprises a support-side cross plate fixed relative to the support post arrangement and defining the first and third reaction surfaces on opposing sides thereof. Optionally, the adjustable headrest assembly comprises first and second headrest-side cross plates fixed relative to the headrest on opposing sides of the support-side cross plate (i.e., located on and spaced from the opposing sides of the support-side cross plate), the first and second headrest-side cross plates defining the second and fourth reaction surfaces, respectively. Such an arrangement is more compact and has a reduced component count in comparison to alternatives in which the first and third reaction surfaces are defined by separate support-side cross plates. Optionally, the first and second headrest-side cross-members and the slider define a carrier which is fixed relative to the headrest; optionally, wherein the slider comprises at least one rod which extends between the first and second headrest-side cross plates. This provides a reduced component count in comparison to alternative configurations in which the first and second headrest-side cross plates and the slider of the slider arrangement are provided by separate components. This may also simplify assembly, since only one carrier needs to be secured to the headrest. Optionally, the support-side cross plate is part of a support component which is fixed relative to the support post arrangement and which comprises the guide of the slider arrangement. This provides a reduced component count in comparison to alternative configurations in which the support cross member and the guide of the slider arrangement are provided by separate components. This may also simplify assembly, since only one support component needs to be secured to the support post arrangement. Optionally, the adjustable headrest assembly comprises a headrest-side cross plate fixed relative to the headrest and defining the second and fourth reaction surfaces on opposing sides thereof. Optionally, the adjustable headrest assembly comprises first and second support-side cross plates fixed relative to the support post arrangement on opposing sides of the headrest-side cross plate (i.e., located on and spaced from the opposing sides of the headrest-side cross plate), the first and second support-side cross plates defining the first and third reaction surfaces, respectively. Such an arrangement is more compact and has a reduced component count in comparison to alternatives in which the second and fourth reaction surfaces are defined by separate headrest-side cross plates. Optionally, the first and second support-side cross plates and the guide define a support component which is fixed relative to the support post arrangement. Optionally, the first and second support-side cross plates are connected by the guide of the slider arrangement. This provides a reduced component count in comparison to alternative configurations in which the first and second support-side cross plates and the guide of the slider arrangement are provided by separate components. This may also simplify assembly, since only one support component needs to be secured to the headrest. Optionally, the headrest-side cross plate is part of a carrier which is fixed relative to the headrest and which comprises the respective slider of the slider arrangement. This provides a reduced component count in comparison to alternative configurations in which the headrestside cross plate and the slider of the slider arrangement are provided by separate components. This may also simplify assembly, since only one carrier needs to be secured to the support post arrangement. Optionally, the adjustable headrest assembly comprises a support component which is fixed relative to the support post arrangement and which extends towards the headrest from the support post arrangement. Optionally, the support component comprises the first reaction surface and defines the guide of the slider arrangement. It will be understood that because the support component extends towards the headrest from the support component, and defines the guide, the guide can be supported at a position between the support post arrangement and the headrest, which provides a compact arrangement. In addition, such a support component may simplify assembly since the guide and part defining the first reaction surface do not need to be separately coupled to the support post arrangement. Optionally, the support component further comprises the third reaction surface (e.g., defined on an opposing side of a plate of the support component to the first reaction surface, or defined by a separate plate of the support component to the first reaction surface). This provides a reduced component count in comparison to alternative configurations in which the third reaction surface is provided by a separate component. This may also simplify assembly, since only one support component needs to be secured to the support post arrangement. Optionally, the support component is a unitary component. In other words, the guide of the slider arrangement is integrally formed with the part that defines the first reaction surface. This simplifies assembly in comparison to alternative configurations where the guide is coupled (e.g., fastened) to another part to form the support component. Optionally, the adjustable headrest assembly comprises a carrier which is fixed relative to the headrest and which extends towards the support post arrangement from the headrest. Optionally, the carrier comprises the second reaction surface and defines the slider of the slider arrangement. It will be understood that because the carrier extends towards the support component from the headrest, and defines the slider, the slider can be positioned between the support post arrangement and the headrest, which provides a compact arrangement. In addition, such a support component may simplify assembly since the slide and part defining the second reaction surface do not need to be separately coupled to the headrest. Optionally, the carrier is a unitary component. In other words, the slide of the slider arrangement is integrally formed with the part that defines the second reaction surface. This simplifies assembly in comparison to alternative configurations where the guide is coupled (e.g., fastened) to another part to form the carrier. Optionally, the carrier further comprises the fourth reaction surface. This provides a reduced component count in comparison to alternative configurations in which the fourth reaction surface is provided by a separate component. This may also simplify assembly, since only one carrier needs to be secured to the headrest. Optionally, the headrest is mounted to the carrier. The headrest may be mounted to the carrier directly or indirectly via one or more intermediate components. In some embodiments, a spring or other resilient element is provided between the first and second reaction surfaces (e.g., a tensioned resilient element for urging the first and second reaction surfaces towards each other). Such a spring or other resilient element may be provided instead of or as well as the third and fourth reaction surfaces and flexible bladder positioned therebetween, e.g., as an alternative means of driving movement of the slider along the slide path. Optionally, one of the slider or guide comprises at least one rod extending along the slide path and the other of the slider or guide comprises at least one bearing surface which is annular or part-annular. Optionally, the at least one rod is positioned against the at least one bearing surface to facilitate sliding of the slider relative to the guide. In other words, the at least one bearing surface defines at least one guide bore in which the at least one rod is received. Such a configuration having rod(s) and annular / part-annular bearing surface(s) provides a simple slider arrangement which constrains movement of the slider relative to the guide to directions along the slide path. In this context, it will be understood that the term “annular or part-annular” refers to a shape which defines an opening or part of an opening (e.g., generally ring-shaped or part ring-shaped), but not necessarily a curved or circular shape. For example, the rod(s) may have a non-circular cross-sectional shape (e.g., square) and the bearing surface(s) may define an internal surface having a corresponding non-circular cross-sectional shape (e.g., defining a square-shaped opening) in which the rod(s) are received. Optionally, the at least one rod comprises at least two spaced-apart rods, and the at least one bearing surface comprises at least two spaced-apart bearing surfaces. Optionally, each rod is positioned against a corresponding one of the bearing surfaces to facilitate sliding of the slider relative to the guide. Having at least two rods and corresponding at least two bearing surfaces (i.e., annular or part-annular surfaces) provides a more robust slider arrangement, which also inhibits rotation of the slider about the guide (e.g., about the rod axis). Optionally, the adjustable headrest assembly comprises an insert, sleeve or coating coupled to the guide and / or the slider. For example, a low friction coating may be provided within the bearing surface(s) and / or on the rod(s). As used herein, the term “support post arrangement” refers to one or more support posts configured to extend between the seat back and the headrest assembly. The term “support post” is used to refer to a rigid upright configured to extend between the seat back and the headrest assembly during use and by which the headrest assembly is connected to and supported by the seat back. This includes, but is not limited to, one or more rods and / or plates which are configured to extend between the seat back and the headrest assembly. For example, the support post arrangement may comprise a single plate configured to extend between the seat back and the headrest assembly. The support post arrangement may comprise one or more discrete components which are configured to be secured to the seat back. Alternatively, or in addition, the support post arrangement may be integral with the seat back. For example, the support post arrangement may be formed by an extension of the seat back, such as a portion of a frame of the seat back. The support post arrangement may comprise a single support post. The single support post may be positioned centrally or offset from a central of the headrest. Optionally, the support post arrangement comprises at least two spaced-apart support posts. A further aspect of the disclosure provides an automobile seat assembly for a vehicle. The automobile seat assembly comprises: a seat comprising a seat back; and an adjustable headrest assembly as disclosed herein. The support post arrangement is secured to the seat back, and the fluid actuator is configured to drive movement of the slider along the slide path in order to translate the headrest relative to the seat back (e.g., forwards or backwards relative to the seat back). Such an automobile seat assembly benefits from the advantages of the adjustable headrest assembly outlined above. Optionally, the seat assembly further comprises a fluid pump (e.g., a pneumatic pump) configured to supply pressurised fluid to the fluid actuator of the adjustable headrest. A further aspect of the disclosure provides a vehicle comprising an adjustable headrest assembly as disclosed herein and / or an automobile seat assembly as disclosed herein. Such a vehicle benefits from the advantages of the adjustable headrest assembly 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 side view of a vehicle in accordance with an embodiment of the invention; Figure 2 shows a schematic view of a seat adjustment system of the vehicle of Figure 1; Figure 3 shows a schematic side view of an automobile seat assembly of the vehicle of Figure 1; Figure 4A shows a perspective sectional view of an adjustable headrest assembly of the automobile seat assembly of Figure 3 in a central state; Figure 4B shows a perspective sectional view of the adjustable headrest assembly of Figure 4A in a rearward state; Figure 4C shows a perspective sectional view of the adjustable headrest assembly of Figures 4A and 4B in a forward state; Figure 5A shows a plan sectional view of the adjustable headrest assembly of Figures 4A to 4C in the central state; Figure 5B shows a plan sectional view of the adjustable headrest assembly of Figures 4Ato 5A in the rearward state; Figure 5C shows a plan sectional view of the adjustable headrest assembly of Figures 4A to 5B in the forward state; Figure 6A shows a side sectional view of the adjustable headrest assembly of Figures 4A to 5C in the central state; Figure 6B shows a side sectional view of the adjustable headrest assembly of Figures 4A to 6A in the rearward state; and Figure 6C shows a side sectional view of the adjustable headrest assembly of Figures 4A to 6B in the forward state. DETAILED DESCRIPTION Examples of the present disclosure relate to an adjustable headrest assembly for an automobile seat, a seat adjustment system and an automobile seat assembly. Non-limiting examples will now be described with reference to accompanying Figures 1 to 6C, where the figures illustrate a vehicle 10, an adjustable automobile seat assembly 30, a seat adjustment system 60, and an adjustable headrest assembly 100 for an automobile seat. Figure 1 illustrates a vehicle 10 having a front 12, a rear 14, a lower end 16, and an upper end 18. The vehicle 10 includes a vehicle body 20 forming the structure of the vehicle 10, and to which features of the vehicle 10, such as doors, may be attached. The vehicle 10 also includes wheels 22 for moving the vehicle body 20 over a ground surface. A prime mover 24 is provided for propelling the wheels 22. For example, the prime mover 24 may include: an internal combustion engine, and / or a battery-powered electric drive unit (EDU) having one or more electric machines, and / or any other suitable type of prime mover. In the description below, the term "longitudinal" will be used in relation to a longitudinal axis X-X of the vehicle 10 (as illustrated on Figure 1). Such an axis / direction may also be referred to as an "x-axis" or "x direction" of the vehicle 10. The longitudinal axis X-X extends between the front 12 and the rear 14 of the vehicle 10. The term "lateral" will be used in relation to a lateral axis Y-Y of the vehicle 10. Such an axis / direction may also be referred to as a "y-axis" or "y direction" of the vehicle 10. The lateral axis Y-Y extends transverse to the longitudinal axis X-X (e.g., between a left side and a right side of the vehicle 10). The term “vertical” will be used in relation to vertical axis Z-Z of the vehicle 10 (as illustrated on Figure 1). Such an axis / direction may also be referred to as a “z-axis” or “z-direction” of the vehicle 10. The vertical axis Z-Z extends transverse to the longitudinal axis X-X and the lateral axis Y-Y (e.g., between the lower end 16 and the upper end 18 of the vehicle 10). The vehicle 10 has an automobile seat assembly 30 (illustrated schematically in Figure 1). The automobile seat assembly includes a seat base 32 configured to be sat on by a driver or passenger, a seat back 34 for supporting a back of the driver or passenger when sat on the seat base 32, and a headrest 36 for supporting the head of a driver or passenger sat on the seat base 32. The automobile seat assembly 30 of the vehicle 10 of Figure 1 is adjustable. In particular, the vehicle 10 incudes a seat adjustment system 60 for the automobile seat assembly 30, as will be described in more detail below. Referring now to Figure 2, the seat adjustment system 60 includes one or more adjustment actuators 62. The one or more adjustment actuators 62 may be used for adjusting one or more portions of the automobile seat assembly 30. For example, the one or more adjustment actuators 62 may be part of an adjustable headrest assembly 100 of the kind illustrated in Figures 4A to 6C, described below. The seat adjustment system 60 also includes an actuation power source 64 and one or more actuation lines 66 coupling the actuation power source 64 to the one or more adjustment actuators 62. In the illustrated configuration, the seat adjustment system 60 also includes one or more control elements 68 between the actuation power source 64 and the one or more adjustment actuators 62, for controlling power supplied from the actuation power source 64 to the one or more adjustment actuators 62 along the actuation line(s) 66. A control system 70 is provided for controlling the actuation power source 64 and / or the one or more control elements 68, in order to selectively actuate the one or more adjustment actuators 62 to adjust the automobile seat assembly 30 accordingly. In the illustrated configuration, one or more user inputs 72 (e.g., buttons, switches, touchscreen inputs, etc.) may be provided to send an input to the control system 70 to indicate a desired adjustment of the automobile seat assembly 30. The control system 70 may comprise a controller. The controller may comprise processing means and memory means. The processing means may be one or more electronic processing devices which operably execute computer-readable instructions. The memory means may be one or more memory devices. The memory means may be electrically coupled to the processing means. The memory means may be configured to store instructions, and the processing means may be configured to access the memory means and execute the instructions stored thereon. In the illustrated embodiment, the seat adjustment system 60 is a fluid actuation system (e.g., pneumatic or hydraulic system). For example, the actuation power source 64 is a fluid pump (e.g., pneumatic or hydraulic pump) and each adjustment actuator 62 is a fluid actuator which is configured to receive pressurised fluid from the fluid pump 64, in order to adjust the corresponding portion of the automobile seat assembly 30. The one or more actuation lines 66 are fluid pipes which are each coupled to a corresponding fluid port of the fluid actuator(s) 62. The one or more control elements 68 are provided by a valve arrangement which is configured to control flow of fluid to / from the fluid actuator(s) 62 along the one or more fluid pipes 66. The valve arrangement 68 may include a plurality of valves which are collocated in a valve block and / or separate valves. The valve block and / or valves may be positioned at any suitable location along the actuation line(s) 66. In embodiments where the seat adjustment system 60 is a pneumatic system, the fluid pump 64 may receive air from an ambient environment surrounding the fluid pump 64 (e.g., the interior of the vehicle 10) and pump this to the fluid actuator(s) 62. Air leaving the fluid actuator(s) 62 may be discharged to the ambient environment via an exhaust. In embodiments where the seat adjustment system 60 is a hydraulic system, a hydraulic fluid reservoir (e.g., tank) may be provided. In such embodiments, the fluid pump 64 may pump hydraulic fluid from the hydraulic fluid reservoir to the fluid actuator(s) 62. Hydraulic fluid leaving the fluid actuator(s) 62 may be returned to the hydraulic fluid reservoir. In some embodiments, the seat adjustment system 60 is part of the automobile seat assembly 30. In other words, the actuation power source 64, control element(s) 68, actuation line(s) 66 and adjustment actuator(s) 62 are all coupled to a suitable portion of the automobile seat assembly 30. In other embodiments, one or more of these components is provided elsewhere within the vehicle 10. Referring now to Figure 3, the adjustable automobile seat assembly 30 of the vehicle 10 of Figure 1 is illustrated in more detail. In the illustrated embodiment, the adjustable automobile seat assembly 30 includes an adjustable headrest assembly 100. The adjustable headrest assembly 100 includes the headrest 36 and a support post arrangement 102 for securing the headrest 36 to the automobile seat assembly 30 (i.e., to the seat back 34). The adjustable headrest assembly 100 also includes a fluid actuator 62 which is connected to the seat adjustment system 60. As will be described in more detail below, the fluid actuator 62 is configured to translate the headrest 36 transversely relative to the support post arrangement 102 (e.g., in first and second sliding directions D1 and D2). It will be understood that because the support post arrangement 102 is secured to the seat back 34 of the automobile seat assembly 30, the fluid actuator 62 is configured to translate the headrest 36 relative to the rest of automobile seat assembly 30 (e.g., forwards and backwards relative to the seat back 34 of the automobile seat). This allows the headrest position to be adjusted to suit the driver sat in the automobile seat assembly 30. In addition, since the support post arrangement 102 is received within the seat back 34 (e.g., approximately parallel to a central axis of the seat back 34), then the fluid actuator 62 is configured to translate the headrest 36 in directions which are substantially perpendicular to the central axis of the seat back 34. In other words, the first and second sliding directions D1, D2 are substantially perpendicular (e.g., within 30 degrees of perpendicular) to the central axis of the seat back 34. In the illustrated orientation of the seat back 34, this corresponds to the fluid actuator 62 translating the headrest 34 longitudinally forwards and backwards within the vehicle 10. Referring now to Figures 4A to 6C, the adjustable headrest assembly 100 is illustrated in more detail. The illustrated support post arrangement 102 includes two spaced-apart support posts 102A, 102B. The support posts 102A, 102B are connected by one or more post cross-members 102C which extend transversely between the support posts 102A, 102B. In alternative embodiments, other suitable support post arrangements may be used (e.g., including one support post or more than two support posts). The support posts 102A, 102B may be received within corresponding openings in the seat back 34. The adjustable headrest assembly 100 includes a slider arrangement 104 coupling the headrest 36 to the support post arrangement 102. The slider arrangement 104 includes a guide 106 fixed relative to the support post arrangement 102 and a slider 108 fixed relative to the headrest 36. The slider 108 is slidably connected to the guide 106 to translate along a slide path P which is transverse to the support post arrangement 102 (e.g., in first and second sliding directions D1, D2 along the slide path P). In the illustrated embodiment, the slider 108 includes at least one rod 110 extending along the slide path P and the guide 106 includes at least one bearing surface 112 which is annular or part-annular. In particular, there are two spaced-apart rods 110 and two corresponding spaced-apart bearing surfaces 112. The rods 110 are each positioned against a corresponding one of the bearing surfaces 112 to facilitate sliding of the slider 108 relative to the guide 106. In other words, the bearing surfaces 112 define guide bores in which the rods 110 are received. In this context, it will be understood that the term “annular or part-annular” refers to a shape which defines an opening or part of an opening (e.g., generally ring-shaped or part ring-shaped), but not necessarily a curved or circular shape. For example, in some embodiments the rods 110 may have a non-circular cross-sectional shape (e.g., square) and the bearing surfaces 112 may define an internal surface having a corresponding noncircular cross-sectional shape (e.g., defining a square-shaped opening) in which the rods 110 are received. In some embodiments, the adjustable headrest assembly 100 includes an insert, sleeve or coating coupled to the guide 106 and / or the slider 108. For example, a low friction coating may be provided within the bearing surfaces 112 and / or on the rods 110, to facilitate sliding therebetween. In some embodiments, the arrangement of the rods 110 and bearing surfaces 112 may be reversed from the illustrated arrangement. For example, the guide 106 may include one or more rods which are fixed relative to the support post arrangement 102, and the slider may include one or more corresponding bearing surfaces which slide along the rods. As previously mentioned, the adjustable headrest assembly 100 includes a fluid actuator 62. The fluid actuator 62 is configured to drive movement of the slider 108 along the slide path P in order to translate the headrest 36 transversely relative the support post arrangement 102. As will be described in more detail below, the fluid actuator 62 includes at least one flexible bladder 114, 116 which is configured to receive pressurised fluid to enlarge the at least one flexible bladder 114,116 in order to push the slider 108 along the slide path P. In particular, there is a flexible bladder 114 configured to push the slider 108 in a first sliding direction D1 along the slide path P (e.g., a forwards direction). There is also a further flexible bladder 116 configured to push the slider 108 in a second sliding direction D2 along the slide path P (e.g., a rearwards direction). Each of the flexible bladders 114, 116 may include at least on fluid port (not illustrated) coupled to the one or more fluid pipes 66 of the automobile seat actuation system 60, for receiving pressurised fluid from the fluid pump 64 in order to enlarge the flexible bladder 114, 116. The control system 70 may be configured to adjust the valve arrangement 68 so that fluid is expelled from one of the flexible bladders 114, 116 while fluid is supplied to the other flexible bladder 114, 116. This results in a simultaneous contraction / expansion of the different flexible bladders 114, 116. The flexible bladders 114, 116 are illustrated schematically in Figures 4A to 6C. It will be understood that the shape of the flexible bladders 114,116 may differ from the schematic shape shown in the figures. Any suitable shape may be used. In the illustrated embodiment, the flexible bladders 114,116 each have a primary expansion direction which is generally aligned with the slide path P. In particular, each flexible bladder 114, 116 may be configured so that, as the flexible bladder 114, 116 is enlarged in use, expansion of the flexible bladder 114, 116 in directions transverse to the primary expansion direction is less than 20%, e.g., less than 10%, e.g., less than 5%, of the expansion in the primary expansion direction. For example, as best illustrated in Figures 5B and 5C, a width W of each flexible bladder 114, 116 (measured in a direction transverse to the slide path P) remains approximately constant as the flexible bladders 114, 116 are enlarged and contracted. In contrast, a length L of each flexible bladder 114, 116 (measured along the primary expansion direction, i.e., generally parallel to the slide path P) varies as the flexible bladder 114, 116 is enlarged and contracted. In more detail, each of the flexible bladders 114,116 has first and second ends 118,120 which are substantially perpendicular to the slide path P (as illustrated in Figure 5A). Each of the flexible bladders 114, 116 also has one or more sides 122 (e.g., concertinaed or elasticated sides) extending substantially parallel to the slide path P and connecting the first and second ends 118, 120. In this way, the first and second ends 118, 120 may be pushed apart from each other in a direction parallel to the slide path P as the flexible bladder 114, 116 is enlarged by pressurised fluid (e.g., by stretching the one or more sides 122 in the direction parallel to the slide path P). In such a configuration, the one or more sides 122 may be inhibited from bulging outwards in directions transverse to the slide path P. In other embodiments, the flexible bladders 114, 116 may not have a particular primary expansion direction. For example, the flexible bladders 114, 116 may be elasticated bladders which expand approximately equally in all directions, and which are guided into particular shapes by adjacent rigid structures of the adjustable headrest assembly 100. As will be described in more detail below, the first and second ends 118, 120 of the flexible bladders 114, 116 define abutment surfaces for engaging corresponding reaction surfaces 124A, 124E3, 124C, 124D which are fixed relative to the support post arrangement 102 and headrest 36, in order to drive movement of the slider 108 along the slide path P as the respective flexible bladder 114, 116 is enlarged. As best illustrated in Figure 5A, the adjustable headrest assembly 100 has a first reaction surface 124A which is fixed relative to the support post arrangement 102, and a second reaction surface 124B which is fixed relative to the headrest 36 and which faces the first reaction surface 124A. The flexible bladder 114 is positioned between the first and second reaction surfaces 124A, 124B, so that it acts on the first and second reaction surfaces 124A, 124B to increase a spacing distance therebetween as it is enlarged. In this way, the flexible bladder 114 can drive movement of the slider 108 along the slide path P in the first sliding direction D1. In the illustrated embodiment, the first and second reaction surfaces 124A, 124B are positioned so that a separation distance between the headrest 36 and the support post arrangement 102 is increased as the spacing distance between the first and second reaction surfaces 124A, 124B is increased. For example, Figures 4C, 5C and 6C show a forward state of the adjustable headrest assembly 100 in which the flexible bladder 114 is enlarged to increase the spacing distance between the first and second reaction surfaces 124A, 124B. The adjustable headrest assembly 100 also has a third reaction surface 124C which is fixed relative to the support post arrangement 102, and a fourth reaction surface 124D which is fixed relative to the headrest 36 and which faces the third reaction surface 124C. The further flexible bladder 116 is positioned between the third and fourth reaction surfaces 124C, 124D, so that it acts on the third and fourth reaction surfaces 124C, 124D to increase a spacing distance therebetween as it is enlarged. In this way, the further flexible bladder 116 can drive movement of the slider 108 along the slide path P in the second sliding direction D2. In the illustrated embodiment, the third and fourth reaction surfaces 124C, 124D are positioned so that a separation distance between the headrest 36 and the support post arrangement 102 is decreased as the spacing distance between the third and fourth reaction surfaces 124C, 124D is increased. For example, Figures 4B, 5B and 6B show a rearward state of the adjustable headrest assembly 100 in which the further flexible bladder 116 is enlarged to increase the spacing distance between the third and fourth reaction surfaces 124C,124D. It will be understood that the flexible bladder 114 between the first and second reaction surfaces 124A, 124B may receive pressurised fluid to increase the internal volume thereof at the same time as pressurised fluid being expelled from the further flexible bladder 116 between the third and fourth reaction surfaces 124C, 124D to reduce the internal volume thereof, and vice versa. For example, the control system 70 may be configured to achieve this via control of the valve arrangement 68. In this way, two-way control of the position of the headrest 36 relative to the support post arrangement can be achieved by adjusting which flexible bladder 114, 116 the pressurised fluid is delivered to. It will be understood that, because the first and second sliding directions D1, D2 are opposite directions along the slide path P, the first to fourth reaction surfaces 124A, 124B, 124C, 124D are positioned so that the spacing distance between the first and second reaction surfaces 124A, 124B increases as the spacing distance between the third and fourth reaction surfaces 124C, 124D decreases, and vice versa. In some embodiments, a spring or other resilient element (not illustrated) is provided between the third and fourth reaction surfaces 124C, 124D (e.g., compressed spring for urging the third and fourth reaction surfaces 124C, 124D apart). Such a spring or other resilient element may be provided instead of or as well as the further flexible bladder 116 provided between the third and fourth reaction surfaces 124C, 124D, e.g., as an alternative means of driving movement of the slider 108 along the slide path P in the second sliding direction D2. In some embodiments, a spring or other resilient element (not illustrated) is provided between the first and second reaction surfaces 124A, 124B (e.g., a tensioned resilient element for urging the first and second reaction surfaces 124A, 124E3 towards each other). Such a spring or other resilient element may be provided instead of or as well as the third and fourth reaction surfaces 124C, 124D and further flexible bladder 116 positioned therebetween, e.g., as an alternative means of driving movement of the slider 108 along the slide path P. In the illustrated embodiment, the adjustable headrest assembly 100 has a support-side cross plate 126 fixed relative to the support post arrangement 102 and defining the first and third reaction surfaces 124A, 124C on opposing sides thereof. In the illustrated embodiment, the support-side cross plate 126 is fixed to the one or more post cross-members 102C via one or more connecting plates 128A, 128E3 (e.g., upper and lower connecting plates 128A, 128B, as illustrated in Figures 6A to 6C). In the illustrated embodiment, the support-side cross plate 126 is part of a support component 134 which is fixed relative to the support post arrangement 102 and which includes the guide 106 of the slider arrangement 104. In particular, the bearing surfaces 112 of the guide 106 are provided at sides of the support-side cross plate 126. The illustrated support component 134 extends towards the headrest 36 from the support post arrangement 102. In particular, the connecting plates 128A, 128B are part of the support component 134, and extend away from the support post arrangement 102 so that the support-side cross plate 126 is separated from the support post arrangement 102. The support component 134 may be a unitary component. In other words, the guide 106 of the slider arrangement may be integrally formed with the support-side cross plate 126. Alternatively, the different parts of the support component 134 may be produced separately and secured together (e.g., fastened, adhered, welded, etc.). In alternative embodiments, the support-side cross plate 126 and the guide 106 are secured separately to the support post arrangement 102. The adjustable headrest assembly 100 also has first and second headrest-side cross plates 130A, 130A which are fixed relative to the headrest 36 on opposing sides of the support-side cross plate 126 (i.e., located on and spaced from the opposing sides of the support-side cross plate 126). The first and second headrest-side cross plates 130A, 130B define the second and fourth reaction surfaces 124B, 124D, respectively. In the illustrated embodiment, the first and second headrest-side cross-plates 130A, 130B and the slider 108 define a carrier 132 which is fixed relative to the headrest. In particular, the rods 110 of the slider 108 extend between the first and second headrest-side cross plates 130A, 130E3 to connect them together. By virtue of the rods 110 extending away from the headrest 36, the carrier 132 extends towards the support post arrangement 102 from the headrest 36. The carrier 132 may be a unitary component. In other words, the slide 108 of the slider arrangement 104 may be integrally formed with the headrest-side cross plates 130A, 130B. Alternatively, the different parts of the carrier 132 may be produced separately and secured together (e.g., fastened, adhered, welded, etc.). In the illustrated embodiment, the headrest 36 is mounted to the directly to the carrier 132. In other embodiments, the headrest 36 may be mounted to the carrier 132 indirectly via one or more intermediate components. In alternative embodiments, the headrest-side cross plates 130A, 130B are separate to the slider 108 (e.g., the rods 110 may be fixed directly to the headrest 36, and the headrest-side cross plates 130A, 130B may be fixed to the headrest 36 separately to the rods 110). In alternative embodiments, the adjustable headrest assembly 100 may have a single headrest-side cross plate which is fixed relative to the headrest 36 and which defines the second and fourth reaction surfaces 124B, 124D on opposing sides thereof. In such embodiments, a pair of first and second support-side cross plates which fixed relative to the support post arrangement 102 may be provided on opposing sides of the headrest-side cross plate (i.e., located on and spaced from the opposing sides of the headrest-side cross plate). The first and second support-side cross plates may define the first and third reaction surfaces 124A, 124C, respectively. In such embodiments, the single headrest-side cross plate may be part of a carrier which is fixed relative to the headrest 36 and which comprises the respective slider 108 of the slider arrangement 104. Similarly, the first and second support-side cross plates and the guide 106 may define a support component which is fixed relative to the support post arrangement 102. In such embodiments, the first and second support-side cross plates may be connected by the guide 106 of the slider arrangement 104. For example, the guide 106 may comprise one or more rods 110, and the slider 108 may comprise one or more corresponding bearing surfaces 112. In alternative configurations, there may be two headrest-side cross plates and two support-side cross plates defining the first to fourth reaction surfaces 124A to 124D (e.g., two pairs of spaced-apart cross plates). 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.

Claims

1. An adjustable headrest assembly for an automobile seat, the adjustable headrest assembly comprising: a headrest;a support post arrangement for securing the headrest to an automobile seat;a slider arrangement coupling the headrest to the support post arrangement, wherein the slider arrangement comprises a guide fixed relative to the support post arrangement and a slider fixed relative to the headrest, the slider being slidably connected to the guide to translate along a slide path which is transverse to the support post arrangement; anda fluid actuator configured to drive movement of the slider along the slide path in orderto translate the headrest transversely relative the support post arrangement.

2. The adjustable headrest assembly of claim 1, wherein the fluid actuator comprises at least one flexible bladder configured to receive pressurised fluid to enlarge the at least one flexible bladder in orderto push the slider along the slide path.

3. The adjustable headrest assembly of claim 2, wherein the at least one flexible bladder has a primary expansion direction which is generally aligned with the slide path.

4. The adjustable headrest assembly of claim 3, wherein the at least one flexible bladder is configured so that, as the flexible bladder is enlarged in use, expansion of the flexible bladder in directions transverse to the primary expansion direction is less than 20%, optionally less than 10%, optionally less than 5%, of the expansion in the primary expansion direction.

5. The adjustable headrest assembly of claim 2, 3 or 4, wherein the adjustable headrest assembly comprises a first reaction surface which is fixed relative to the support post arrangement, and a second reaction surface which is fixed relative to the headrest and which faces the first reaction surface, wherein the at least one flexible bladder comprises a flexible bladder which is positioned between the first and second reaction surfaces, wherein the flexible bladder is configured to receive pressurised fluid to enlarge the bladder in order to act on the first and second reaction surfaces to increase a spacing distance between the first and second reaction surfaces, and thereby drive movement of the slider along the slide path in a first sliding direction.

6. The adjustable headrest assembly of claim 5, wherein the adjustable headrest assembly comprises a third reaction surface which is fixed relative to the support post arrangement, and a fourth reaction surface which is fixed relative to the headrest and which faces the third reaction surface, wherein the at least one flexible bladder comprises a further flexible bladder positioned between the third and fourth reaction surfaces, wherein the further flexible bladder is configured to receive pressurised fluid to enlarge the bladder in orderto act on the third and fourth reaction surfaces to increase a spacing distance between the third and fourth reaction surfaces, and thereby drive movement of the slider along the slide path in a second sliding direction opposite to the first sliding direction.

7. The adjustable headrest assembly of claim 6, wherein the adjustable headrest assembly comprises:a support-side cross plate fixed relative to the support post arrangement and defining the first and third reaction surfaces on opposing sides thereof, andfirst and second headrest-side cross plates fixed relative to the headrest located on and spaced from opposing sides of the support-side cross plate, the first and second headrest-side cross plates defining the second and fourth reaction surfaces, respectively.

8. The adjustable headrest assembly of claim 6, wherein the adjustable headrest assembly comprises: a headrest-side cross plate fixed relative to the headrest and defining the second and fourth reaction surfaces on opposing sides thereof, andfirst and second support-side cross plates fixed relative to the support post arrangement located on and spaced from opposing sides of the headrest-side cross plate, the first and second support-side cross plates defining the first and third reaction surfaces, respectively.

9. The adjustable headrest assembly of any of claims 5 to 8, wherein the adjustable headrest assembly comprises a support component which is fixed relative to the support post arrangement and which extends towards the headrest from the support post arrangement, wherein the support component comprises the first reaction surface and defines the guide of the slider arrangement.

10. The adjustable headrest assembly of claim 9, wherein the support component is a unitary component.

11. The adjustable headrest assembly of any of claims 5 to 10, wherein the adjustable headrest assembly comprises a carrier which is fixed relative to the headrest and which extends towards the support post arrangement from the headrest, wherein the carrier comprises the second reaction surface and defines the slider of the slider arrangement.

12. The adjustable headrest assembly of any preceding claim, wherein one of the slider orguide comprises at least one rod extending along the slide path and the other of the slider or guide comprises at least one bearing surface which is annular or part-annular, wherein the at least one rod is positioned against the at least one bearing surface to facilitate sliding of the slider relative to the guide.

13. The adjustable headrest assembly of claim 12, wherein the at least one rod comprises at least two spaced-apart rods, and the at least one bearing surface comprises at least two spaced-apart bearing surfaces, wherein each rod is positioned against a corresponding one of the bearing surfaces to facilitate sliding of the slider relative to the guide.

14. An automobile seat assembly for a vehicle, the automobile seat assembly comprising:a seat comprising a seat back; andthe adjustable headrest assembly of any preceding claim, wherein the support post arrangement is secured to the seat back, and wherein the fluid actuator is configured to drive movement of the slider along the slide path in order to translate the headrest forwards or backwards relative to the seat back.

15. A vehicle comprising the adjustable headrest assembly of any of claims 1 to 13 and / or the automobile seat assembly of claim 14.

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