| 摘要 |
1483643 Thermal switches; pressure switches INDUSTRIE PIRELLI SpA 2 Aug 1974 [23 Aug 1973] 34163/74 Heading H1N [Also in Division B7] A wheel rim comprises a temperature/pressure responsive electrical device, the state of which changes upon the tyre temperature rising above/pressure falling below a predetermined value. The device includes a sensing element having two electrical contacts which open or close upon the value being reached, a pair of electrodes passing through the rim and each connected to a respective contact, and a signalling (or transmitting) circuit connected to the electrodes and embedded in a homogeneous material adhered to the rim at a position which will not be within the tyre and rim cavity. A receiver (E) (Fig. 1, not shown) fixed in the vehicle body is in an alarm circuit. The illustrated pressure sensing element 1 (Fig. 2) comprises an elastic diaphragm biased on its upper side via a perforated cap by tyre air pressure and on its underside by a compressed gas, e.g. air or nitrogen. Box 2 is screwed into a bushing 8 which is screwed into position in the rim 9. One contact 6 is connected to the circuit board 12 via diaphragm 3, box 2 and bushing 8, while the other is connected to the circuit board via elements 4, 10. The temperature sensing element (Fig. 3) comprises a metal lamina 3, and a box 2 is directly screwed into the rim. The upper contact 6 is electrically connected to circuit board 12 via the lamina, box, rim and flanges, while the lower contact 6 is connected to the circuit board via elements 4, 10. During assembly the board 12 is secured, e.g. by screws to flanges 15 welded to the rim, and thereafter, utilizing a mould (16) (Fig. 4, not shown) material is injected into the mould space to envelop the circuit board. The circuit board may be embedded in a block of homogeneous material prior to that block being applied to the wheel rim, the rim contacting surface being coated with a synthetic material consistent with that of the block, which material bonds under a compressive force. Suitable materials for the block and bond comprise epoxy resins, polyester resins and polyurethane resins. |
