EP2931554A1

EP2931554A1 - Vehicle seat assembly

Info

Publication number: EP2931554A1
Application number: EP13796134.8A
Authority: EP
Inventors: Mark Pagett
Original assignee: Nissan Motor Manufacturing UK Ltd
Current assignee: Nissan Motor Manufacturing UK Ltd
Priority date: 2012-12-13
Filing date: 2013-11-20
Publication date: 2015-10-21
Also published as: GB201310541D0; GB2508857B; GB2508857A; GB201222444D0; GB2508947A; WO2014091193A1; GB2508947B

Abstract

A seat assembly for a vehicle having a vehicle floor and a vehicle control arrangement, the seat assembly comprising a seat base upon which a user of the vehicle sits, in use, in an elevated position, the user having a Hip Point and a knee point, and adjustment means (20) for adjusting the vertical height of the seat base (14) relative to the vehicle floor and for adjusting the longitudinal position of the seat base in the longitudinal direction of the vehicle. The adjustment means (20) is operable to provide a range of positions for the seat assembly which provides positional comfort for the vehicle user across a selected range of anthropometric body types, and whereby in every position of the seat assembly across the selected range the Hip Point of the driver is elevated above the knee point. (Figure 7)

Description

VEHICLE SEAT ASSEMBLY

Field of the Invention

The invention relates to a seat assembly for a vehicle and , in particular, but not exclusively, to a seat assembly for a land-based automotive vehicle. The invention finds particular application in the field of Light Goods Vehicles (LGVs) but also extends to a seat assembly for other types of vehicle, such as one that travels over sea.

Background to the Invention

It is common in automotive vehicles for the driver of the vehicle, together with the passengers, to sit in a semi-recumbent position with his or her legs extended towards the front of the vehicle. The seat assembly for the driver typically has a seat base upon which the driver sits, and a seat back against which the driver rests his or her back for support. A frame of the seat assembly supports the seat base and the seat back.

It is common for the seat assembly to be adjustable so as to optimise the postural comfort of the driver and the capability of dynamic control of the vehicle via the vehicle controls including, for example, the foot-operated pedals and the steering wheel. Typically, for example, the seat assembly is adjustable in a front-to-rear or longitudinal direction, so as to adjust the position of the seat assembly relative to the vehicle controls. This ensures the vehicle can accommodate drivers of different height and leg length and with different comfort requirements. The seat base height and incline, and the incline of the seat back, may also be adjustable for a similar reason.

Whilst existing mechanisms provide an extent of adjustment over a useful range, in certain vehicle categories the need for flexibility and adjustment is greater. In Light Commercial Vehicles (LCVs) the ability to adjust various positional features of the seat assembly is particularly useful because there are often multiple users of the same vehicle. Light Commercial Vehicles (LCVs), otherwise known as Light Goods Vehicles (LGVs), are commercial carrier vehicles with a light capacity, typically a Gross Vehicle Weight (GVW) of up to 3.5 tonnes. This category of vehicle includes commercially based goods or passenger vehicles such as vans, trucks, taxis and other delivery vehicles, where the driver of the vehicle is frequently entering and exiting the vehicle to unload cargo. Such vehicles are typically designed with inter-city use in mind and therefore require a compromise between being light and compact for easy of manoeuvrability, and having a large load capacity. It is a problem with vehicles of the aforementioned type that the requirements to provide a useful range of adjustment for various seat parameters (e.g. height, position) are not compatible with the requirements for maximising cargo space and minimising vehicle weight. It is with the aforementioned issue in mind that the present invention provides an improved seat assembly that is particularly useful when utilised in a Light Commercial Vehicle (LCV) or a Light Goods Vehicle (LGV).

Summary of the Invention

According to a first aspect of the present invention, there is provided a seat assembly for a vehicle, the seat assembly comprising a seat base upon which a user of the vehicle, typically the driver, is seated, in use, in an elevated position, the user having a Hip Point and a knee point, and the seat assembly comprising adjustment means for adjusting the vertical height of the seat base relative to the vehicle floor and for adjusting the longitudinal position of the seat base in the longitudinal direction of the vehicle. The adjustment means is operable to provide a range of positions for the seat assembly which provides positional comfort for the vehicle user across a selected range of anthropometric body types, and whereby in every position of the seat assembly across the selected range the Hip Point of the driver is elevated above the knee point.

Adjusting the position of the seat assembly both vertically and longitudinally allows the position of the driver relative to the vehicle control pedals to be adjusted so that the driver can maintain a position of comfort, whilst still having optimum control over the pedals which control the vehicle. In addition to the Hip Point and the knee point, the user also defines a heel point which is the position at which the driver's heel makes contact with the vehicle floor when the ball of the foot is placed on the vehicle accelerator pedal. In a preferred embodiment, the seat base remains substantially horizontal for all vertical and longitudinal positions of the seat assembly.

For example, the selected range of anthropometric body types is a range from 5^th centile Japanese female (JF05) to 99^th centile Japanese male (JM99). Alternatively, the selected range of anthropometric body types is a range from 5^th centile American female (JF05) to 99^th centile American male (AM99).

The seat assembly may comprise an upper frame and a lower frame, wherein the lower frame includes a frame section for rigid connected with the vehicle floor. In one example, the lower frame may be elevated towards the rear of the vehicle and inclined downwardly towards the front of the vehicle at an angle of inclination to the horizontal which may be, for example, between 20 and 50 degrees, and optimally about 25 degrees.

The frame section of the lower frame defines a channel. The lower frame may further comprise a slider which is slidingly received within the channel so as to permit longitudinal movement of the slider, relative to the frame section, to adjust the longitudinal position of the seat assembly within the vehicle.

The upper frame and the lower frame may be interconnected by at least one intermediate frame having an upper section which is connected to the upper frame and hinged to a lower section which is connected to the lower section so as to adjust the vertical position of the seat assembly within the vehicle.

By way of example, the upper frame and the lower frame may be interconnected so that hinged movement of one relative to the other also results in adjustment of the longitudinal position of the seat assembly within the vehicle. The seat assembly may, for example, comprise first and second intermediate frames, a first intermediate frame connecting a rear bar of the upper frame to a rear bar of the lower frame and a second intermediate frame connecting a front bar of the upper frame to a front bar of the lower frame.

In one embodiment, the first and second intermediate frames may be of different length. Due to the lower frame being inclined forwards and downwards, the opening and closing of the upper frame relative to the lower frame results in a degree of longitudinal movement of the upper frame. If the lengths of the upper and lower frame sections of the second intermediate frame are longer than the upper and lower frame sections of the first intermediate frame, this ensures the upper frame stays substantially horizontal during raising and lowering movement, and so the seat base stays substantially horizontal, to improve seating comfort for the occupant.

In one embodiment, a first intermediate frame has first and second parts hinged about a first axis and a second intermediate frame has first and second parts hinged about a second axis, and wherein the first axis lies rearward of the second axis for all vertical positions of the upper frame relative to the lower frame.

In another embodiment, a first intermediate frame has first and second parts hinged about a first axis and a second intermediate frame has first and second parts hinged about a second axis, and wherein the first axis lies forward of the second axis for all vertical positions of the upper frame relative to the lower frame. I n this case, the second intermediate frame may define an opening through which the first intermediate frame projects for all vertical positions of the upper frame relative to the lower frame. According to a second aspect of the present invention, there is provided a vehicle having a seat assembly in accordance with the first aspect of the invention. In particular, the vehicle is a land-based automotive vehicle and particular advantages are achieved when used in Light Goods Vehicle (LGVs) of the type used for deliveries and the like. In such vehicles there are often a multiple number of different users, so that there is a requirement for an adjustable mechanism which provides a wide range of different seating positions to accommodate all the different user requirements for comfort and control. In addition, entry and exit to the vehicle is often frequent. By seating the driver in an elevated position, such entry to and exit from the vehicle is improved and the user is less likely to undergo strain or injury in climbing into and out of the vehicle cabin. In addition, safety is improved as the risk of injury to the chest and legs during a collision is improved.

It will be appreciated that the seat assembly is particularly advantageous when employed as the seat for a driver of a vehicle, but benefits are also obtained when employed as a seat for a passenger of the vehicle.

A further advantage of the seat assembly of the invention is that it provides a higher Hip Point for the vehicle operator, which means that they ride higher in the vehicle. This has been found to make the driver feel more comfortable behind the wheel.

Where it is necessary to manufacture the vehicle to be suitable for a wide range of anthropometric body types, ranging, for example, from JF05 to AM 99, the seat assembly provides the full range of optimum seating positions for comfort and control over a reduced longitudinal adjustment length compared with a conventional seating arrangement in which the user of the vehicle is seated in a semi-recumbent position with the Hip Point below the knee point. This means that the vehicle cabin can be of reduced length compared with a conventional arrangement, so that the overall length of the vehicle can be reduced or at least a greater cargo space can be made available behind the vehicle cabin for storage. A further benefit is that vehicle manufacturers can select a suitable anthropometric body type range for a selected market and need only provide a seat assembly having an adjustment mechanism which achieves positional comfort and suitability of control across the selected range of interest. Typically the longitudinal adjustment length is between 40-50% shorter than that in a conventional vehicle, and typically around 44-45% shorter.

A reduced longitudinal adjustment length is further beneficial in designing the layout of the vehicle cabin, for mass saving and therefore fuel economy, as it reduces the amount of floor space that is needed to accommodate the driver's seat, as well as reducing the physical size of the fore - aft seat adjustment mechanism parts.

In order to achieve these benefits, the seat adjustment mechanism provides an increased vertical adjustment length to ensure that a full or useful range of anthropometric body types are accommodated comfortably and safely. Typically, for example, the seat adjustment mechanism adjusts the vertical height of the seat assembly by at least twice as much as in a conventional seat assembly.

It will be appreciated that preferred and/or optional features of the first aspect of the invention may be incorporated alone, or in appropriate combination, within the second aspect of the invention also. Brief description of the drawings

Figure 1 is a schematic view of a driver of a vehicle in a conventional seating position;

Figure 2 is a schematic diagram of the driver of the vehicle in Figure 1 , to illustrate the definitions of pedal to heel (PH) gap and HH (heel to hip) gap;

Figure 3 is a schematic view of a driver of a vehicle in a seating position provided by a seat assembly of the present invention, compared with the driver in Figures 1 and 2;

Figure 4 is a schematic diagram of the driver of the vehicle in the seating position provided by the seat assembly of the present invention, to illustrate the HH gap and the Heel Step;

Figure 5 is another schematic diagram of a driver seated in the seating position provided by the seat assembly of the present invention; Figure 6 is a graph to show the dynamic envelope for the seat assembly of the present invention, which is the range of Heel Step (HS) vs. PH gap for a driver seated in the seat assembly;

Figure 7 is a side view of a seat adjustment mechanism of a first embodiment of the seat assembly of the present invention; Figure 8 is a perspective view of the seat adjustment mechanism in Figure 7 when in its lowest and rearmost position;

Figure 9 is a perspective view of the seat adjustment mechanism in Figures 7 and 8 when in its uppermost and rearmost position; Figure 10 is a perspective view of the seat adjustment mechanism in Figures 7 to 9 when in its lowest and foremost position;

Figure 1 1 is a perspective view of the seat adjustment mechanism in Figure 7 to 10 when in it uppermost and foremost position;

Figure 12 is a perspective view of a lower frame of the seat adjustment mechanism, which permits adjustment in a longitudinal (fore/aft) direction;

Figure 13 is a perspective view of a runner forming part of the lower frame in Figure 12;

Figure 14 is an enlarged view of a first part of the seat adjustment mechanism in Figures 7 to 13 which permits adjustment in an up/down direction;

Figure 15 is an enlarged view of a second part of the seat adjustment mechanism in Figures 7 to 13 which permits adjustment in an up/down direction;

Figure 16 is an enlarged view of a third part of the seat adjustment mechanism in Figures 7 to 13 which permits adjustment in an up/down direction;

Figure 17 is an enlarged view of a fourth part of the seat adjustment mechanism in Figures 7 to 13; and Figure 18(a) is a side view of an upper part of the seat adjustment mechanism of a second embodiment of the seat assembly of the present invention; Figure 18(b) is a perspective view of the seat adjustment mechanism in Figure 18(a) when in a fully elevated state and Figure 18(c) is a perspective view of the seat adjustment mechanism in Figures 18(a) and (b) when in a fully lowered state. Detailed description of preferred embodiments

Referring to Figure 1 , a driver occupant 10 in a conventional vehicle is seated in a semi- recumbent position in which his or her legs are outstretched towards the front of the vehicle. The driver is seated on a seat assembly 12 having a seat base 14 and a seat back 16, both of which are adjustable so as to provide a range of different seating positions to accommodate the preferences of different drivers with regard to comfort and capability of vehicle control.

Referring to Figure 2, in order to define or measure a seat assembly or occupant's seating position in a vehicle in either two or three dimensions, the automotive industry has adopted a convention which refers to several vehicle 'hard points' and the distances between them, namely the Hip Point of the driver 10, a Heel Step and the Hip-to-Heel (HH) gap. Generally the Hip Point of the driver 10 represents the idealised position of the driver's hip and, specifically, the pivot point between the torso and the thigh of the occupant's body. The Heel Point of the driver 10 is defined as the point where the driver's heel makes contact with the vehicle floor when the ball of the driver's foot is placed on the vehicle accelerator pedal. The Heel Step of the occupant is defined as a vertical distance between the driver's Hip Point and the driver's Heel Point. The Hip-to-Heel (HH) gap is the distance, in the longitudinal direction of the vehicle (i.e. a horizontal measurement), between the Heel Point and the Hip Point. The Pedal-to-Hip (PH) gap is the distance, in the longitudinal direction of the vehicle (i.e. a horizontal measurement), between the Pedal Point and the Hip Point, where the Pedal Point is the geometric centre point of the accelerator contact surface with the driver's foot.

Although not indicated on Figure 2, the Knee Point is defined as the relative position of the theoretical rotation centre of the knee to the other named hard points when measured in two or three dimensions.

Figure 3 compares a conventional seating position for a driver in a vehicle with a seating position provided by a seat assembly of the present invention. The rearmost image of the driver 10 represents the conventional seating position (position Y), and the foremost image of the driver 10 represents the seating position provided by the present invention (position X). Figures 4 and 5 show the Heel Step measurement which is a vertical measurement between the Heel Point and the Hip Point.

Figure 3 shows that for a conventional seating position, the hip point is typically at 372mm above the vehicle floor, compared to a Hip Point of 660 mm in the present invention. In the conventional seating position the HH gap is typically 703 mm, compared with 483mm in the present invention. It can therefore be seen that in the present invention the driver of the vehicle is seated in an elevated seating position, and much closer to the front of the cabin than in a conventional arrangement. In the present invention the driver is seated so that the Hip Point is always above the knee point (i.e. there is a greater distance between the vehicle floor and the hip than between the vehicle floor and the knee). By the driver of the vehicle adopting the seating position provided by the present invention, compared to the conventional seating position, it can be seen that the driver position is moved forwards in the vehicle by around 220mm. The present invention provides a seating assembly that gives a maximum heel step of 680mm, with a maximum saving in the horizontal dimension of 250mm. One advantage of utilising the seat assembly of the present invention is therefore that less distance is required in the cabin of the vehicle, in the longitudinal direction of the vehicle, to accommodate the seat assembly. For application in Light Goods Vehicles (LGVs), for example, this provides the advantage that a greater load space can be provided rearward of the vehicle cabin for the same overall length of vehicle. Alternatively, the overall length of the vehicle can be reduced for the same cargo volume, hence reducing the overall mass of the vehicle.

A further advantage is obtained in that, starting from a more elevated position, with a greater Heel Step, it is much easier for a driver to enter and exit the vehicle. In conventional seating arrangements a driver will often have to pull himself up out of the seating position, which is relatively low in the vehicle, and this can lead to discomfort or injury. For frequent entry/exit vehicles such as delivery vans and the like, the seating assembly of the present invention provides a particular advantage that the entry and exit manoeuvre is much easier. For elderly, infirm or disabled drivers, the elevated seating position provides a particular benefit. As shown in Figure 5, the seat assembly of the present invention also includes a seat base 14 and a seat back 16, the lower end of which abuts or engages the rear side of the seat base 14. Both the seat base 14 and the seat back 16 are adjustable so that the various aforementioned parameters which define the seating position can be varied according to the preference of the driver for postural comfort and the capability to control the vehicle. Figure 6 shows a dynamic envelope, or seat adjustment range, of the seat assembly of the invention. The seat adjustment range is the idealised region of adjustment of the Heel Step versus the PH gap which is required to provide an optimum position of comfort and control for substantially all anthropometric body sizes. This is recognised, internationally, to be the range of anthropometric body types from JF05 to AM99, where JF05 represents a 5^th percentile Japanese female (JF05) representing some of the smaller people of the world and AM99 represents a 99th percentile American male representing larger people in the population. In order to accommodate this full range of body types, the seat assembly is required to provide an adjustment length of 130 mm for the Heel Step and 200mm for the PH gap, as indicated by Region A on the seat adjustment range. In some conventional vehicles, where the driver adopts a semi-recumbent position, the seat assembly may typically provide a horizontal (PH gap) adjustment of 240mm and a vertical adjustment of 50mm, and this is intended to cover a range of anthropometric body types between JF05 and AM90. The PH gap adjustment range is considerably greater in the conventional arrangement, by 40mm, compared with the seat assembly of the present invention. This means that the seat assembly of the present invention does not require such a large length of translation, in the longitudinal direction of the vehicle, for the full range of horizontal adjustment to be accommodated, and across substantially the full range of body types. In other words, the seat assembly of the present invention can cover a full range of comfort positions, for a full range of anthropometric body types, for a significantly reduced extent of adjustment in both the vertical and longitudinal directions.

Whilst a vertical adjustment range of 130mm is required of the present invention to provide a position of comfort for the full range of body types, compared to perhaps only 50mm in a conventional arrangement, this does not impact the cargo space that is available in a Light Goods Vehicle (LGV), for example. Furthermore, by increasing this vertical adjustment height to 130mm, a full range of body types is accommodated comfortably, from JF05 to AM99, compared to a range of only JF05 to AM90 as in a conventional arrangement.

The points for JF30 (30^th percentile Japanese Female) and JM05 (5^th percentile Japanese Male) are also identified on the seat adjustment range in Figure 6 to illustrate how the seat assembly need only provide a selected range of adjustment, depending on the particular usage of the vehicle. So, for example, for a predominantly Japanese market, it may only be required for a vehicle manufacturer to provide a range of adjustment that covers a position of comfort from JF05 to JM95. I n this case a PH gap adjustment of 140mm is required, and a Heel Step adjustment of 130mm is required, as indicated in Figure 6. In practice this provides a considerable advantage for vehicle manufacturers as vehicles are often only marketed with a particular user group in mind.

Figures 7 to 1 1 show various views, and positions of, a seat assembly 20 of the present invention upon which the seat cushion (not shown) and the seat back (also not shown) of the seat assembly are supported. It is an important feature of the seat assembly that, for all positions within the adjustment range, the seat cushion is maintained in a substantially horizontal position.

The seat assembly 20 includes an adjustment mechanism including an upper frame 22 and a lower frame 24. The upper frame 22 supports the seat base (not shown) in a substantially horizontal position. The lower frame 24 is mounted to the floor of the vehicle (also not shown) so that it is inclined at an angle of approximately 25 degrees to the horizontal with the lowermost end of the frame 24 towards the front of the vehicle. The lower frame 24 is therefore said to be inclined downwards and forwards. The upper frame 22 includes an upper front bar 26, an upper rear bar 28 and left and right side bars 30, 32 respectively. The lower frame 24 includes left and right side bars, 38, 40 respectively (only one bar 38 is visible in the view shown in Figure 7) and front and rear cross bars, 34 and 36 respectively. The seat adjustment mechanism is provided with a means for locking the upper and lower frames in a plurality of different vertical and longitudinal positions, depending on the positional comfort and control requirements of the user, as will be described in further detail below. When in the locked position, the seat adjustment mechanism must be able to withstand crash forces.

The upper frame 22 and the lower frame 24 are interconnected by first and second folding intermediate frames, 42, 44 respectively. The first intermediate frame 42 connects the rear bar 28 of the upper frame 22 to the rear bar 36 of the lower frame 24 and the second intermediate frame 44 connects the front bar 26 of the upper frame 22 to the front bar 34 of the lower frame 24.

The first intermediate frame 42 comprises two sections, an upper frame section 42a and a lower frame section 42b which are foldable together so as to provide a scissor-lift action to raise the vertical height of the upper frame 22 relative to the lower frame 24. The upper frame section 42a comprises left and right side arms which extend forward from the rear bar 28 of the upper frame 22 to a rear and laterally extending cross bar 46 located forward of the rear bars 28, 36 and vertically between the upper and lower frames 22, 24. The upper frame section 42a also includes a laterally extending strengthening bar 25 (as can be seen in Figure 9), extending between the left and right side arms, which improves the rigidity of the frame section 42a. The left and right side arms of the first intermediate frame 42 connect to the rear cross bar 46 at hinges A on the bar, with one hinge A located on the left hand side of the cross bar 46 and one hinge A located on the right hand side of the rear cross bar 46.

The lower frame section 42b also comprises left and right side arms and a strengthening bar (not visible in Figure 9), as for the upper frame section 42a. The left and right side arms of the lower frame section 42b extend forward from the rear bar 36 of the lower frame 24 to the rear cross bar 46 and connect thereto at the left and right side hinges A. In this way the upper and lower frame sections 42a, 42b are coupled together in a hinged fashion at the rear cross bar 46 so that the end portions of the sections 42a, 42b, which are connected to the upper or lower bars, 28, 36 respectively, are able to fold together or open apart about the hinges A. The rear cross bar 46 therefore defines a hinge axis for the upper and lower frame sections 42a, 42b of the first intermediate frame 42.

The second intermediate frame 44 is of similar construction to the first intermediate frame 42. Upper and lower frame sections 44a, 44b of the second intermediate frame 44 extend rearward from the front bar 26 of the upper frame 22 to connect with a front and laterally extending cross bar 48. The upper frame section 44a comprises left and right side arms which extend rearward to connect with a respective one of left and right side hinges B on the front cross bar 48. Likewise, the lower frame section 44b comprises left and right side arms which extend rearward to connect with a respective one of the left and right side hinges B. The front bar 48 therefore defines a hinge axis about which the upper and lower sections 44a, 44b of the second intermediate frame 44 are hinged. The hinges A on the rear cross bar 46 are located rearward of the hinges B on the front cross bar 48 for all vertical positions of the seat adjustment mechanism. The second intermediate frame 44 also includes a laterally extending strengthening bar for both the upper and lower frame sections 44a, 44b, although only the lower strengthening bar 45 is visible and is identified in Figure 9. The upper and lower frame sections 44a, 44b of the second intermediate frame 44 are longer than the corresponding first and second frame sections 42a, 42b of the first intermediate frame 42, for reasons that will become apparent in the following description. As can also be seen most clearly in Figure 9, the front and rear cross bars 48, 46 are connected together by left- and right-side threaded rods 50, 52. Each threaded rod 50, 52 carries a slider (not labelled) which is carried on its corresponding rod 50, 52 in a screw- threaded manner towards the rear end thereof. A worm gear 55, 57 is provided at each end of the front cross bar 48, as can be seen in further detail in Figures 16 and 17. The second intermediate frame 44 is also provided with a rotary control mechanism 54, as shown in Figure 9, which may be controlled by means of a user within the vehicle cabin to adjust the extent of opening or closing of the first and second intermediate frame sections 42, 44 about their respective hinge axes, via the worm gears 55, 57. The rotary control mechanism 54 may be wound clockwise or anti-clockwise and serves to either move the seat adjustment mechanism into an expanded state, in which the upper frame 22 is in an elevated position relative to the lower frame 24 (e.g. Figure 9), or a compressed state in which the upper frame 22 is in a lowered position in which it lies in close proximity to the lower frame 24 (e.g. Figure 8).

As the rotary control mechanism is turned, the left- and right-side threaded rods 50, 52 are caused to rotate, causing the sliders to ride along the rod lengths, either back or forth, depending on the direction of rotation of the rotary control mechanism 54. As the sliders translate in a forwards direction along the side bars 50, 52, the rear cross bar 46 is pulled forwards so that the upper and lower sections 42a, 42b of the first intermediate frame 42 are closed together. Conversely, as the sliders translate in the rearwards direction, the rear cross bar 46 is pushed rearwards so that the upper and lower sections 42a, 42b of the first intermediate frame 42 are opened apart. The front cross bar 48 is caused to move in a corresponding manner so that the upper and lower sections 44a, 44b of the second intermediate frame 44 open and close correspondingly.

When the seat adjustment mechanism is in the rearmost and lowermost position, the upper and lower sections 42a, 42b of the first intermediate frame 42 are closed together about the hinges A so as to be brought into relatively close contact with one another in a compressed configuration. Likewise the upper and lower sections 44a, 44b of the second intermediate frame 44 are brought into relatively close contact with one another as they are closed together about the hinges B. It will be appreciated that in the lowermost position of the upper frame 22 (e.g. Figure 10) the front and rear cross bars 48, 46 are brought together so as to be in relatively close contact with one another, in a longitudinal direction of the vehicle, compared with when in the uppermost position (e.g. Figure 11) in which the front and rear cross bars 48, 46 are relatively far apart in the longitudinal direction of the vehicle. The first and second intermediate frames 42, 44 therefore provide a scissor-lift action to raise and lower the vertical height of the upper frame 22, relative to the lower frame 24.

The seat cushion of the seat assembly is carried or supported by the upper frame 22 and, hence, adjustment of the seat adjustment mechanism in the vertical direction allows the height of the seat assembly (seat cushion plus seat back) to be adjusted. A range of different heights are permitted between the elevated and lowered positions so as to provide for a range of different comfort settings for the vehicle user, depending on the degree of adjustment of the rotary control mechanism. The seat adjustment mechanism permits the full seat adjustment range of Heel Step vs. PH gap to be achieved, as shown in Figure 6, so as to accommodate the optimum position of comfort across a full range of anthropometric body types.

Referring also to Figures 12 and 13, the lower frame 24 also comprises left-and right- side runners 60, 62 which are rigidly fixed to the vehicle floor. The left and right-side runners 60, 62 provide an anchorage for the seat assembly to the vehicle, but also provide a means of adjusting the horizontal position of the seat assembly in the longitudinal direction of the vehicle. This is achieved through cooperation between a corresponding one of left- or right-side sliders 64, 66 and a corresponding channel provided in the runners 60, 62.

A cross bar 68 is connected towards the rear end of each runner 60, 62. The cross bar 68 carries an electric motor assembly 70 which is controlled by means of a user-operated control unit in the vehicle cabin. The electric motor 70 drives the cross bar 68 to rotate, which, via a worm gear 71 , 73 provided at each end thereof, serves to adjust a respective, threaded fore/aft adjustment bar 75, 77, one on each side of the assembly. The adjustment bars 75, 77 cooperate with the sliders 64, 66 to cause the sliders 64, 66 to move back and forth within the runners 60, 62 to adjust the longitudinal position of the seat assembly between a relatively forward position, as shown in Figures 10 and 1 1 , and a relatively rearward position, as shown in Figures 8 and 9.

Due to the lower frame 24 being inclined forwards and downwards, the opening and closing of the upper frame sections 42a, 44a with their respective lower frame sections 42b, 44b results in a degree of longitudinal movement of the upper frame 22, and for this reason the length of the upper and lower frame sections 44a, 44b of the second intermediate frame 44 are of longer length than the upper and lower frame sections 42a, 42b of the first intermediate frame 42 so as to ensure the upper frame 24 stays substantially horizontal during raising and lowering movement. As the upper frame sections 42a, 44a are caused to move apart from the lower frame sections 42b, 44b, the upper frame 24 is therefore caused to move upwards (vertically) and rearwards (longitudinally). Conversely, as the upper and lower frame sections 42a, 42b, 44a, 44b are closed together, the upper frame 22 is caused to move downwards (vertically) and forwards (longitudinally).

It will be appreciated from Figures 8, 9, 10 and 1 1 that the seat adjustment assembly permits adjustment between a range of different heights, depending on the extent to which the intermediate frames 42, 44 are scissored together about their respective hinges A and B, and a range of different front-to-rear positions, depending on the position of the slide bars 64, 66 within the runners 60, 62, and that any combination of vertical height and longitudinal position can be achieved. A particular benefit of the invention is that the range of different height and longitudinal positions enables the full range of seat positions to be achieved as shown in Figure 6 so as to accommodate the positional comfort requirements of substantially all anthropometric body types. Moreover, these positional comfort requirements can be achieved over a smaller range of longitudinal positions than in a conventional seat assembly where the driver adopts a sem i-recumbent seating position. Typically, for example, the seat adjustment mechanism in Figures 7 to 17 need only provide for a longitudinal adjustment over a range of about 200mm to provide adequate adjustment from JF05 through to AM99, which is a reduction in that required in a conventional seating assembly of around 40mm. Optimally the slide length need only be around 130mm in order to provide similar adjustment to a conventional seat, typically JM05 to AM99, helping to realise a 1 10mm reduction. The maximum Heel Step adjustment (i.e. vertical height) is typically 130mm using the seat adjustment mechanism described previously.

Referring to Figure 18, in an alternative embodiment the seat adjustment mechanism is similar to that described previously, but the arms of the intermediate frame sections 142, 144 are longer. As before the upper section of the first intermediate frame section 142 is coupled with the lower section of the intermediate frame 142 at left- and right-side hinges A. The second intermediate frame section 144 is of similar construction to the first intermediate frame, except that it is noticeably narrower than the first intermediate frame 142. As in the previous embodiment, the upper section of the second intermediate frame is coupled together with the lower section at left- and right-side hinges B. However, in this embodiment the hinges A of the first intermediate frame 142 are further forward relative to the hinges B for the second intermediate frame 144 so as to accommodate the increased length of the frames 142, 144. In addition, the hinges A for the first intermediate frame 142, being a narrower frame, are arranged laterally inward of the hinges B for the second intermediate frame 144. The second intermediate frame 144 defines an opening between left and right side arms thereof and the longer first intermediate frame 142 can therefore project through the opening.

Both manually and electronically operable versions of the seat adjustment mechanism are envisaged. So, for example, longitudinal seat adjustment need not be achieved through the electronic motor assembly 70 shown in the figures, but could be by means of a mechanical mechanism. Likewise, the rotary control mechanism 54 for the vertical seat height adjustment may be replaced with an electronically operable mechanism.

It will be appreciated by a person skilled in the art that the invention could be modified to take many alternative forms to those described herein, without departing from the scope of the appended claims.

Claims

1. A seat assembly for a vehicle having a vehicle floor and a vehicle control arrangement, the seat assembly comprising: a seat base upon which a user of the vehicle is seated, in use, in an elevated position, the user having a Hip Point and a knee point, the seat assembly further comprising adjustment means (20) for adjusting the vertical height of the seat base (14) relative to the vehicle floor and for adjusting the longitudinal position of the seat base in the longitudinal direction of the vehicle, whereby the adjustment means (20) is operable to provide a range of positions for the seat assembly which provides positional comfort for the vehicle user across a selected range of anthropometric body types, and whereby in every position of the seat assembly across the selected range the Hip Point of the driver is elevated above the knee point.

2. The seat assembly as claimed in claim 1 , wherein the seat base (14) remains substantially horizontal for all vertical and longitudinal positions of the seat assembly.

3. The seat assembly as claimed in claim 1 or claim 2, wherein the selected range of anthropometric body types is a range from 5^th centile Japanese female (JF05) to 99^th centile Japanese male (JM99).

4. The seat assembly as claimed in claim 1 or claim 2, wherein the selected range of anthropometric body types is a range from 5^th centile American female (JF05) to 99^th centile American male (JM99).

5. The seat assembly as claimed in any of claims 1 to 4, comprising an upper frame (22) and a lower frame (24), wherein the lower frame includes a frame section (60, 62) for rigid connected with the vehicle floor.

6. The seat assembly as claimed in claim 5, wherein the lower frame is elevated towards the rear of the vehicle and inclined downwardly towards the front of the vehicle at an angle of inclination to the horizontal.

7. The seat assembly as claimed in claim 6, wherein the angle of inclination is between 20 and 50 degrees.

8. The seat assembly as claimed in any of claims 5 to 7, wherein the frame section defines a channel and wherein the lower frame (24) further comprises a slider (64, 66) which is slidingly received within the channel so as to permit longitudinal movement of the slider, relative to the frame section (60, 62) to adjust the longitudinal position of the seat assembly within the vehicle.

9. The seat assembly as claimed in claim 8, wherein the upper frame (22) and the lower frame (24) are interconnected by at least one intermediate frame (42, 44; 142, 144) having an upper section which is connected to the upper frame and hinged to a lower section which is connected to the lower section so as to adjust the vertical position of the seat assembly within the vehicle.

10. The seat assembly as claimed in claim 9, wherein the upper frame (22) and the lower frame (24) are interconnected so that hinged movement of one relative to the other also results in adjustment of the longitudinal position of the seat assembly within the vehicle.

1 1. The seat assembly as claimed in claim 10, comprising first and second intermediate frames (42, 44; 142, 144), a first intermediate frame connecting a rear bar (28) of the upper frame (22) to a rear bar (36) of the lower frame (24) and a second intermediate frame connecting a front bar (28) of the upper frame (22) to a front bar (34) of the lower frame (24).

12. The seat assembly as claimed in claim 11 , wherein the first and second intermediate frames (42, 44; 142, 144) are of different length.

13. The seat assembly as claimed in any of claims 9 to 12, comprising a first intermediate frame (42; 142) having first and second parts (42a, 42b) hinged about a first axis (48) and a second intermediate frame (44; 144) having first and second parts (44a, 44b) hinged about a second axis (46), and wherein the first axis lies rearward of the second axis for all vertical positions of the upper frame (22) relative to the lower frame (24).

14. The seat assembly as claimed in any of claims 9 to 12, comprising a first intermediate frame (42; 142) having first and second parts (42a, 42b) hinged about a first axis (48) and a second intermediate frame (44; 144) having first and second parts (44a, 44b) hinged about a second axis (46), and wherein the first axis lies forward of the second axis for all vertical positions of the upper frame (22) relative to the lower frame (24).

15. The seat assembly as claimed in claim 14, wherein the second intermediate frame (144) defines an opening through which the first intermediate frame (142) projects for all vertical positions of the upper frame (22) relative to the lower frame (24).

16. A vehicle comprising a seat assembly as claimed in any of claims 1 to 15.

17. The vehicle as claimed in claim 16, being a land-based automotive vehicle.

18. The vehicle as claimed in claim 17, wherein the control arrangement includes an operating pedal for engagement by a foot of the vehicle user, the operating pedal defining a pedal point and a pedal-to-hip (PH) gap which is the distance, in the longitudinal direction of the vehicle, between the pedal point and the Hip Point, and wherein the pedal- to-hip gap is no more than 200mm.

19. A seat assembly substantial ly as herein described with reference to the accompanying figures.

20. A vehicle substantially as herein described with reference to the accompanying figures.