Page Comparison

• H Point: The theoretical location of the occupant’s hip. This is the pivot point of both the torso and the upper leg. Many dimensions will be relative to this.

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• 5 Point / 6 Point Harness: A seatbelt with 5 or 6 belts in total. It restrains the movement of the occupant more than a 3 Point Seatbelt and is safer

  • 5 Point Harness

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    • 1 & 2: Shoulder Belts

    • 3 & 4: Lab Lap Belts

    • 5: Anti Sub Belt

• 6 Point Harness

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  • Similar setup to 5 Point Harness however Antisub Belt is two separate belts

• Passthroughs: Cutouts in the seat to allow the belts of a 5 or 6 Point Harness to pass through the seat uninterrupted (as shown by the red circles in the image below)

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• Seatback: The portion of the seat which supports the back and shoulders of the occupant

• Headrest: The portion of the seat which supports the head and/or neck of the occupant

  • In race/bucket seats this will be the area above the shoulder belt passthroughs

• Seatpan: The portion of the seat which supports the buttock and upper leg of the occupant

• Bolsters: Protrusions/barriers typically found on the seatback or seatpan of the seat (shown by the red circles in the image below) They keep the occupant centered in the seat during cornering.

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• Undepressed Seat Contour: The shape of the seat cushioning (typically viewed from the side) when no occupant has sat in it

• Depressed Seat Contour: The shape of the seat cushioning (typically viewed from the side) when an occupant is sitting in the seat - causing the cushioning to compress

• ILD/IFD: Acronym for Indentation Load Deflection or Indentation Force Deflection. A test to determine the stiffness of a foam. Manufacturers will typically specify the stiffness of their foam in ILD/IFD

  • In this test a circular flat indenter is pressed against a foam sample of standardized width, length and height. 60 seconds after the indenter has achieved 25% or 50% compression, the force is measured 

  • Higher ILD/IFD values = stiffer foam

  • 25% ILD/IFD is for a 25% compression

  • 50% ILD/IFD is for a 50% compression

  • US measurements are in pound-force

  • European measurements are in newtons

General Guidelines

• Seatback should provide full contact from: Top of Pelvis to Shoulder  [4]

  • Headrest will provide contact for Head and/or Neck

• Beyond the 325mm line that is above the H Point (will be shown in diagrams further below) the geometry should be fairly flat  [4]

  • Ergonomics of this will be described in Pressure Distribution Section

Lumbar Support

• Preferred apex of lumbar support (i.e. where it protrudes out the most): 152mm above the H Point  [4]

  • Or 150mm above the H Point [6]   (only a 2mm difference, doesn’t really matter which one is used)

• Preferred prominence of a fixed, non-movable lumbar support (i.e. how much it protrudes): 20mm  [6]

• Preferred prominence of a movable lumbar support: 30mm  [6]

• Range of motion for a movable lumbar support: 100mm - 200mm above the H Point  [6]

• Lumbar Support Cushioning should not compress more than 80%  [6]

  • Greater than 80% compression leads to decrease in water vapor diffusion, leading to increase in local humidity

Depressed Seatback Cushion Contour  [4]

• Assumed this was approximately 99th Percentile Male, thus H Point is 135mm away from Depressed Seatback Cushion Contour

• Depressed Cushion Contour is the bolded black line that is pointed at by the red arrow in the image below

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    • Steps to recreate this Depressed Cushion Contour in CAD

      • Draw torso line (a line emanating from the H Point, at the angle that you have determined the occupant will be sitting at)

      • Draw three perpendicular lines to the torso line

        • At 115mm, 160mm and 325mm from the H Point

        • Each of these lines (in this case) are 135mm long though depending on the occupant it may be a different length for you

      • Draw a line connecting the endpoints of the 325mm and 115mm line

      • At the endpoint of the 115mm line, construct an arc with 100mm radius that will stop at the stiffer/base layer foam below it

Undepressed Seatback Cushion Contour [4] & [6]

• Still under assumption we are using a 99th Percentile Male as the occupant - H Point is 135mm away from the depressed seatback cushion contour

  • Source 4 undepressed seatback cushion contour 

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      • NOTE: For MSXIV a fixed lumbar support was used, thus to have a 20mm prominence all Y-values above were multiplied by 0.4

• Source 6 undepressed seatback cushion contour

  • Due to manufacturing concerns, source 4’s undepressed seatback cushion contour may be too complicated to make, source 6’s is merely an arc - which makes manufacturing much easier

  • Radius for fixed lumbar support: 300mm

  • Prominence for fixed lumbar support of this type: 15-20mm

  • Radius for lumbar support of this type that can adjust its radius (separate from adjusting the height of the apex): 240mm 250mm - 400mm

  • Prominence for radius adjustable lumbar support of this type: 0-30mm

    
    

    

Temperature Regulation [6]

• If bare skin will be touching the cover material, the material should not go above33°C +/- 1.4°C during operation

• Minimum surface heat flux of cover material: 75W/m^2

  • Perforating the cover material in specific areas can greatly increase its surface heat flux value