Patent GB-190405891-A (GB)
Title: Improvements in the Means for Automatically Inflating Pneumatic Tyres
Inventor: EDWARDS ARTHUR HENRY
Filed: 1904-03-10
Granted: 1905-03-10
Abstract: 5891. Edwards, A. H. March 10. Wheels with pumps or other air-compressing appliances.-Relates to means for inflating pneumatic tyres by the motion of the wheel, the pumping-mechanism being automatically thrown out of gear when a predetermined pressure is exceeded. The pump casing A<3>, Fig. 1, rotating with the wheel, contains the hollow piston A' fitted with a non-return valve A<6> and connected to a pivoted segmental. piece B<8> by link B<10>. The casing is connected with the tyre by a tube A<7>, also fitted with a non-return valve A<6>. A spring-controlled lever B' pivoted on the spindle B<3> is made to oscillate by contact with a cam B fixed to the axle. On the same spindle B<3> is mounted a segmental ratchet-wheel B<4>, connected with the segmental piece B<8> by the link B<7>. The pawl B<5>, pivoted to the lever B', rotates the ratchet-wheel and raises the piston A' for the suction stroke against the action of the spring C ; when the pivot B<x> passes the dead centre, the spring C is free to contract and a rapid delivery stroke is made. As the pressure approaches the required maximum, the piston no longer completely drives out its charge of air, so that the pivot B<x> does not descend to its lowest position ; the pawl B<5> is now in contact with a smooth portion of the ratchet-wheel, which is in consequence not rotated ; on the pressure diminishing the piston descends, and the mechanism comes into gear again. In a modification, Fig. 2, the crank C<4> and link B' are worked by a pin on a worm-wheel C' rotated by a worm C<2>; the link B<7> is slotted to a length equal to the throw of the crank C<4>. When the piston fails to expel the full charge, the mean position of the lower end of the link B<7> rises, and finally the link oscillates under the action of the pin, but no longer reciprocates the pump until the pressure falls. In another modification, Fig. 3, the piston.rod is connected to the ratchet-wheel B<4> by a slotted link D ; when the mean position of the piston is raised, the path of the link D is altered so that the projection D<3> strikes against a pin d on the tumbler D<4>, rotates it past its dead centre against the action of the spring D<x>, and causes the shoulder d' to strike back the bell-crank lever D<5>, whereupon a pin d<6> rotates and holds back the lever B<x>, rigidly mounted on the same axis as the lever B', which is thus lifted off the cam B. When the pressure falls, the motion of the connecting-link D causes the nose D' to strike back the pin d', and the above movements are reversed. Fig. 4 shows an arrangement in which variation of pressure causes a spring diaphragm E in connection with the tyre to reciprocate and the movement is communicated by projections E<1> on the rod E<2> through the spring- controlled tumbler E<4> to a lever E<5> which moves the pawl B<5> into, or out of, engagement with the teeth of the ratchet-wheel. The movement of the diaphragm may be caused to vary the speed of the pump by means of a quadrant piece, mounted close to, and on the same spindle as, the ratchetwheel and formed with an arm actuated by the diaphragm. Increase of pressure causes the sector to advance and mask some of the teeth of the ratchet and thus diminish the active stroke of the pawl. In another arrangement, the pump is fixed between the rim and hub, and is operated by a shoe normally out of contact with the ground, which when the tyre is partially deflated is rocked by contact with the ground. In another arrangement, the pump is driven by toothed gearing ; a wheel mounted on the axle gears with a planetwheel to which the connecting-rod of the pump is attached, and a clutch mounted on the axle and actuated by a spring diaphragm through a lever throws the clutch into, and out of, gear. In the construction shown in Fig. 8, the pump is actuated by segmental wheels K<6>, K', and, when the maximum pressure is reached, a spring diaphragm pushes up the piece L with the lever L<2> so that the pin L<1> engages with a slot K<x> <x> cut in the wheel K<4> and holds the roller B<1> off the cam. In a modification, the connecting-rod may be pivoted to a piece adapted to slide relatively to the piston-rod with which it is made to engage and disengage by a pawl actuated by a spring diaphragm..