Patent GB-1419961-A (GB)
Title: Seats
IPC: B60N2/52
Filed: 1972-12-01
Abstract: 1419961 Shock absorbers DUNLOP Ltd 9 Feb 1973 [18 Feb 1972 1 Dec 1972 (2) 12 Aug 1972] 55492/72 7547/72 3279/73 and 3280/73 Divided out of 37732/72 55493/72 Heading F2S [Also in Division A4] A seat assembly, e.g. for a tractor, comprises a seat provided with a vibration damping mounting including two rigid members 3, 4 mounted for relative rotation about pivot pins 10, and a pouch 2 adapted to be filled with pressurized fluid and disposed between the members 3, 4 whereby vertical movement of the seat results in pivoting of the members towards each other and so compression of the pouch and increase in the area of contact of the pouch with the members 3, 4. The members 3, 4 are in the form of plates, the plate 3 forming part of a mounting base and the plate 4 being secured to the arms of a U-shaped bar 5 pivotally supporting the seat front, the arms being pivoted at their ends on the pivot pins 10 carried by the plate 3. The U-shaped bar 5 may be replaced by separate side levers pivotally connected to the seat and the pins 10. The pouch 2 is made from textile reinforced rubber or unreinforced elastoplastic material and is clamped between the plate 4 and a strip 13, and it has an inlet pipe 18 for the supply of air from a hand pump 20 and an air outlet pipe 19 having an adjustable pressure release valve 21. Alternatively, a single pipe having a combined non-return and exhaust valve may be used and may be fed from a tyre foot pump or static air supply, or from an air supply of the tractor. A damping and guiding system for the seat comprises rollers 27, 28 positioned at each side of the seat back and engaging with the internal surfaces of the flanges of channels 24 secured to the seat base, the larger load bearing rollers 27 engaging direct with the flange material and the smaller rollers 28 being pre-loaded into engagement with rubber strips 29 bonded to plates 30 bolted to the channel flanges. The rollers 27, 28 are mounted in blocks 23 each having a boss slidably contacting the base of the associated channel 24 to provide lateral guidance, Fig. 3 (not shown). The damping effect of the rubber strips 29 may be varied by shims 36 under the plates 30. The upward movement of the seat is limited by stops 110 and its downward movement by engagement of the arms of the bar 5 with bolt heads 32a on the base, or by a rubber stop. A tank (not shown) may be connected the pouch to increase the effective air volume of the pouch, and the connection could be through a flow restrictor orifice to provide damping. Alternatively, a more viscous fluid such as oil may be used and the pouch may be connected to a reservoir or via a flow restrictor to a liquid containing chamber in a hydropneumatic accumulator having a diaphragm separating the liquid containing chamber and a pressurized gas containing chamber, and the pressurized gas may be air and the air chamber may have connected to it a pump, a pressure release valve and optionally an extra volume tank. In a second embodiment of the damping and guiding system, Figs. 4 and 5 (not shown), pairs of nylon rollers engage the flanges of the channels 24, one at least of which is rubber lined. Alternatively each pair of the rollers can be replaced by a single roller making rolling contact with a rubber lined flange and skidding contact with the other flange. In a third embodiment Fig. 6 (not shown), the channels have diverging flanges at least one of which is lined with rubber and the flanges are engaged by rollers of corresponding crosssection. In a fourth embodiment, Figs. 7 and 8 (not shown), the rollers are replaced by nylon blocks each having a flat face engaging directly with one flange of a channel and an undulating face engaging a rubber lined flange. In a fifth embodiment, Figs. 9 and 10 (not shown), the undulating faces of the blocks are replaced by rollers. In a sixth embodiment, Fig. 11 (not shown), the channels may be tapered to vary the contact pressure. In a seventh embodiment, Figs. 12A and 12B (not shown), the area of contact between rollers and the rubber lining is varied by varying the width of the lining. The mix of the rubber used may also be adjusted to vary the damping characteristics. The rubber may be replaced by any elastomeric material. The damping and guidance systems may be replaced by a conventional hydraulic damper associated with guide rollers. In another embodiment, Figs. 13 to 15 (not shown), the seat is mounted on side scissor levers. One lever of each pair of levers has one end pivoted to the base and its other end carries a roller engaging in a guide channel on the seat, and the other lever of each pair has one end pivoted to the seat via a horizontal adjustment device and its other end connected to rollers engaging a channel on the base to provide a damping and guidance system similar to that of the first embodiment.