| 摘要 |
The pressure cap 21 is particularly for a degas tank 20 or radiator of a vehicle engine cooling system and has a deformable, pressure-sensitive membrane 28 and an electrical contact switch 27. When a pressure inside the degas tank is equal to or greater than a predetermined pressure limit, e.g. 0.5-0.7 bar, the membrane causes the switch to obtain a first operating state. Otherwise, the switch is in a second operating state. The switch preferably comprises first 29 and second 30 electrically conductive contact surfaces whereby deforming of a resilient portion 31 of the membrane upwards urges the second contact surface into connection with the first, placing the switch in the first state. The cap may include an aperture 33 to introduce air at atmospheric pressure into the cap and a releasable fastener for connection to a neck 20n of the degas tank. An engine system comprising the pressure cap is also claimed whereby a processor preferably compares the operating state of the switch with an expected state based on sensed engine speed and coolant temperature to determine whether there is a coolant leak. A method of preventing a vehicle engine from overheating is also claimed (figure 3). |
